power engineering june 2013

79
We’re Not Exaggerating. Our Boilers are something to brag about. We custom design and custom build boilers to perform efficiently, safely and cleanly. Your RENTECH boiler will lower operating costs, reduce emissions, and provide faster start-up and cool-down. You’ll find satisfied customers on six continents with specialty boilers, HRSGs, wasteheat boilers and fired packaged watertube boilers from RENTECH. We’ve been designing and building boilers for people who know and care since 1996. WWW.RENTECHBOILERS.COM

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Established in 1896, Power Engineering magazine is the comprehensive voice of the power generation industry that provides readers with the critical information needed to remain efficient and competitive in today's market. For three years in a row, Power Engineering has been named the most read and useful magazine in the power industry. Power Engineering Online provides up-to-the-minute energy news, stock quotes, five years of searchable editorial archives, power generation conference schedule and details, and an industry product and services guide. Power Engineering is part of the PennWell energy group, the largest U.S. publisher of electric power industry books, directories, maps and conferences.

TRANSCRIPT

Page 1: Power Engineering June 2013

We’re Not Exaggerating. Our Boilers

are something to brag about.

We custom design and custom build boilers to perform effi ciently, safely and cleanly.

Your RENTECH boiler will lower operating costs, reduce emissions, and provide faster start-up

and cool-down. You’ll fi nd satisfi ed customers on six continents with specialty boilers, HRSGs,

wasteheat boilers and fi red packaged watertube boilers from RENTECH. We’ve been designing

and building boilers for people who know and care since 1996.

WWW.RENTECHBOILERS.COM

RenBoi_PEdm_1306 1 5/21/13 2:02 PM

Page 2: Power Engineering June 2013

June 2013 • www.power-eng.com

RICE NESHAPWHAT YOU NEED TO KNOW TO COMPLY

GAS TURBINESTHE KEY TO QUICKER STARTUP TIMES

BOILER CLEANINGTHE BEST TECHNIQUES AND STRATEGIES

the magazine of power generation

Emission Control

TECHNOLOGY

thhe magazine of power generatiion e

117YEARS

1306pe_C1 C1 6/4/13 4:07 PM

Page 3: Power Engineering June 2013

March 2013 • www.power-eng.com

EMISSIONS CONTROL UNDERSTANDING YOUR OPTIONS

HYDROPOWER THE POWER OF REHABILITATION

PRB COAL CHALLENGES AND SOLUTIONS

the magazine of power generation

Wind Turbine TECHNOLOGY CHOICES

NHA Spec

ial

Advert

ising

Secti

on 35

-47

117YEARS

the magazine of power generation

the magazine of power generation

A quick start guide to MAXIMIZING our interactive features.Welcome to the Digital Edition of

SHARE an article or page via social media.

Click PAGES to view thumbnails of each page and browse

through the entire issue.

Easily browse all BACK ISSUES.

SEARCH for specific articles or content.

View the table of CONTENTS and easily navigate directly to an article.

DOWNLOAD the issue to your desktop.

PRINT any or all pages.SHARE an article via email.

Easily NAVIGATE through the issue.

Click directly on the page to ZOOM in or out. Fit the issue to your screen.

TabTransition_Template.indd 1-2 3/19/13 6:03 PM

Page 4: Power Engineering June 2013

March 2013 • www.power-eng.com

EMISSIONS CONTROL UNDERSTANDING YOUR OPTIONS

HYDROPOWER THE POWER OF REHABILITATION

PRB COAL CHALLENGES AND SOLUTIONS

the magazine of power generation

Wind Turbine TECHNOLOGY CHOICES

NHA Spec

ial

Advert

ising

Secti

on 35

-47

117YEARS

the magazine of power generation

the magazine of power generation

A quick start guide to MAXIMIZING our interactive features.Welcome to the Digital Edition of

SHARE an article or page via social media.

Click PAGES to view thumbnails of each page and browse

through the entire issue.

Easily browse all BACK ISSUES.

SEARCH for specific articles or content.

View the table of CONTENTS and easily navigate directly to an article.

DOWNLOAD the issue to your desktop.

PRINT any or all pages.SHARE an article via email.

Easily NAVIGATE through the issue.

Click directly on the page to ZOOM in or out. Fit the issue to your screen.

TabTransition_Template.indd 1-2 3/19/13 6:03 PM

Page 5: Power Engineering June 2013

Solvay Chemicals, Inc.

1.800.SOLVAY C (800.765.8292)

www.solvair.us

Copyright 2013, Solvay Chemicals, Inc. All Rights Reserved

When the heat is on…SOLVAir Solutions helps relieve it!

As summer progresses, the heat becomes more unrelenting, and air pollution control remedies

often move to the back burner. But with MATS and MACT deadline mandates just over the

horizon, it’s also vital that compliance solutions be found for SOX and HCl emissions before

much more time elapses.

The good news: Dry Sorbent Injection with sodium sorbents is proven to postpone the

retirement of some coal-fred power plants by reducing SOX and HCl emissions drastically.

SOLVAir Solutions understands the pressures that come with looming regulations deadlines,

and we can help with the resolution of emissions problems.

When the heat is on, staying cool is what it’s all about. For information that helps take the heat

of, call Mike Wood at SOLVAir Solutions, 800.765.8292, or go to www.solvair.us, to fnd out

about DSI, sodium sorbents, emissions control and more.

For info. http://powereng.hotims.com RS# 1

1306pe_C2 C2 6/4/13 4:07 PM

Page 6: Power Engineering June 2013

Power Engineering ®

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P.O. Box 1260, Tulsa, OK 74101Telephone: (918) 835-3161 • Fax: (918) 831-9834

E-mail: [email protected] Wide Web: http://www.power-eng.com

MANAGING EDITOR — Russell Ray

(918) 832-9368 [email protected]

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(770) 578-2688 [email protected]

CHAIRMAN — Frank T. Lauinger

PRESIDENT/CEO — Robert F. Biolchini

CHIEF FINANCIAL OFFICER/SENIOR

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PRODUCTION MANAGER — Katie Noftsger

POWER ENGINEERING, ISSN 0032-5961, USPS 440-980, is published

12 times a year, monthly by PennWell Corp., 1421 S. Sheridan Rd., Tulsa,

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of POWER ENGINEERING may be purchased at a cost of $14 each in

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available on microfilm and microfiche from University Microfilm, a Xerox

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POWER ENGINEERING ONLINE : www.power-eng.com

Industry News:Global updates throughout the day

Newsletter:Stay current on industry news, events, features and more.

Newscast:A concise, weekly update of all the top power generation news

2 Opinion

4 Clearing the Air

6 Nuclear Reactions

8 Demand Response

10 View on Renewables

12 Gas Generation

14 Power Plant Profile

18 What Works

72 Ad Index

FEATURES No. 6, June 2013117VOLUME

20 Extending the Life of Coal Fired Plants Through theUse of Dry Sorbent Injection

40 Gas Turbine Combined Cycle Fast Start:The Physics Behind the Concept

y

Fast start capability is one of the major features of gas turbines that give power plants flexibility in their operations. Learn more about the key mechanisms that limit the startup times of modern combined cycle gas turbines.

28 Advances in BoilerCleaning Technology

From dynamite to the latest in online cleaning systems, Power Engineering looks at methods to keep boilers slag-free and working at peak efficiency.

50 Upgrading Electrostatic PrecipitatorsMany electrostatic precipitators will need to be upgraded or converted into a baghouse to handle particulate matter emission standards regulated by federal standards. Learn more about different methods for upgrading ESPs.

62 Development Status of theAlden “Fish-Friendly” Turbine

Several organizations have been working to advance the construction and installation of a “fish-friendly” turbine design. Read about their efforts and the search for a hydropower project to demonstrate the new technology.

56 Engineering Design forRICE NESHAP Compliance

Read about the steps taken and challenges faced by a team working to bring an NRG Energy peaking plant into compliance with regulations requiring less carbon dioxide emissions.

Many plants are lowering emissions through the use of dry sorbent injection,

which costs a fraction of the price of a wet scrubber. Power Engineering

looks at the benefits of DSI systems for adapting to changing regulations and

compliance dates.

1306pe_1 1 6/4/13 3:54 PM

Page 7: Power Engineering June 2013

www.power-eng.com2

OPINION

on several rulemakings that are sure

to have a significant impact on electric

utilities. Here are three of those forth-

coming rules:

• A final rule governing cooling wa-

ter intake structures at existing

power plants is expected to be is-

sued this month. The rule, which

targets plants using once-through

cooling systems, would require

many facilities to install closed-

cycle cooling systems. Closed-cy-

cle systems use less water from riv-

ers and bays and harm fewer fish.

Under the rule, plants that draw

more than 2 million gallons a day

and use at least 25 percent of that

water for cooling are required to

take action to protect the aquatic

environment. More than 670 U.S.

plants will be affected by the new

rule. The measure will require

some power producers to modify

cooling water intake structures or

construct new cooling towers.

• The EPA is expected to issue a rule

expanding the oversight of coal

ash management and disposal at

U.S. power plants. The rule would

require coal-fired power plants to

eliminate wet ash handling and

phase out surface impoundments,

or ponds, within five years. The

rule was proposed after a 40-acre

coal ash storage pond at Tennes-

see Valley Authority’s Kingston

plant in Harriman, Tenn., failed

in 2008, spilling more than 1 bil-

lion gallons of coal ash slurry. The

big question is this: Will the EPA

classify coal ash as a hazardous or

Navigating the regulatory

maze is a dangerous under-

taking for power producers

nowadays. Developing a sound, cost-

effective strategy for compliance has

been complicated by layers of new en-

vironmental rules and delays in imple-

mentation.

One misstep can set a project back

by years, costing power producers and

their customers millions. New rules

governing mercury emissions, cool-

ing technology, wastewater treatment,

coal ash management, regional haze,

and greenhouse gas emissions pose a

formidable challenge for utility execu-

tives and power plant managers. Some

of these rules have been finalized

while others are in the works.

Successful compliance requires a

carefully coordinated, catchall strategy

that includes a calculated integration

of technologies. Balance is the goal.

A comprehensive plan that achieves

the new environmental standards and

ensures reliable and affordable electrici-

ty is the end-game. But getting there will

be different for every power producer

and every plant.

The maze of environmental rules is

becoming more difficult to navigate.

There are a number of new environ-

mental rules awaiting final action or

implementation. These rules, which

will cost the industry billions in com-

pliance costs, will dictate the future

of power generation in the U.S. for

decades to come. It is very important

these rules be as flexible as possible.

The U.S. Environmental Protection

Agency is expected to move forward

non-hazardous waste? The differ-

ence is significant. A hazardous

classification would cost power

producers billions more in com-

pliance costs.

• In April, the EPA proposed efflu-

ent limitation guidelines to reduce

wastewater discharges from power

plants. The rule is expected to be

finalized by May 2014. The rule

would be the first update of the

effluent limitations guidelines

since 1982. The EPA proposed the

rule after the agency found that

the increased use of air pollution

controls was increasing pollution

in wastewater discharges. The rule

would reduce pollutants from the

following wastewater streams: flue

gas desulfurization, fly ash, bot-

tom ash, flue gas mercury control,

landfills and surface impound-

ments, nonchemical metal clean-

ing wastes, and fuel gasification.

You may have noticed a commonal-

ity in all of these measures. All three

rules call for significantly stricter stan-

dards for water usage in power plants.

The change in the EPA’s focus is clear.

After decades of advancing clean-air

regulations, the agency plans to put a

higher priority on new water rules for

power producers. At POWER-GEN In-

ternational 2013 in Orlando, Fla., all

of these rules and their impacts will

be thoroughly examined by experts

participating in several conference ses-

sions. To register online, visit www.

power-gen.com. If you have a question

or a comment, please contact me at

[email protected].

ManagingRegulatory MayhemBY RUSSELL RAY, MANAGING EDITOR

1306pe_2 2 6/4/13 3:54 PM

Page 8: Power Engineering June 2013

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Page 9: Power Engineering June 2013

www.power-eng.com4

CLEARING THE AIR

also be removed by injecting alkali

such as trona or lime/hydrated lime

upstream of PAC injection. The main

drawback of the PAC system is its

potential adverse effect on ESP per-

formance when ESP is used for par-

ticulate collection and to improve the

salability of fly ash. A new market en-

trant, injection of amended silicates,

can potentially negate both increased

SO3 concentration in the flue gas and

the attendant adverse effect on ESP

performance. The long-term viability

of amended silicate has not yet been

demonstrated, however.

Halogen compounds such as bro-

mine or hydrogen bromide added to

flue gas increase the conversion of

elemental mercury to ionic mercury,

thereby facilitating mercury capture

in downstream FGD. Halogen salts

can also be added to coal before the

pulverizers. During combustion, bro-

mide salts decompose and release

bromine ions, which in turn oxidize

elemental mercury to ionic mercury

that is removed in FGD. Bromine ions

can potentially increase fireside cor-

rosion. Some ionic mercury collected

in the FGD can revert back to elemen-

tal mercury and can be re-emitted

into the flue gas. Although chemicals

can be added to minimize re-emis-

sion, the exact mechanisms of the re-

emission reactions and the mitigation

measures are not clearly established.

Given the complexity of choos-

ing control technologies for limiting

mercury emissions, a comprehensive

site-specific study may be necessary

to help your company choose the op-

timal solution.

T he optimal selection of control

technologies to limit mercury

emissions depends on the type

of coal-fired unit (new or existing),

the rank of the coal and existing emis-

sion control systems.

Mercury in coal varies from 0.05

to 0.25 parts per million by weight,

depending on the type of coal. The

established regulatory limits on mer-

cury emissions depend on the type of

unit and the type of coal. The limits for

new coal-fired units are 0.04 lb/GWh

for units that burn low-rank coal such

as lignite with a higher heating value

(HHV) of less than 8,300 Btu/lb,

and 0.003 lb/GWh for units burning

high-rank coal with an HHV of more

than 8,300 Btu/lb. For existing units,

the corresponding limits are 0.12 lb/

GWh or 11.0 lb/TBtu and 0.013 lb/

GWh or 1.2  lb/TBtu, respectively.

These emission limits translate to re-

moval efficiency ranges of 65 percent

to more than 80 percent for new units

using low-rank coals and 95 percent

to more than 98 percent for new units

burning high-rank coals. The removal

efficiency ranges for existing units are

15 percent to more than 50 percent

for low-rank coals and 85 percent to

95 percent for high-rank coal.

Because the removal requirements

are based solely on lb/GWh, opera-

tors of new units may find that low-

mercury coal and the ultra super-crit-

ical steam cycle, which yield very low

heat rates in the range of 8,000 Btu/

KWh, offer substantial benefit. For

existing units, the control technology

selection depends on the removal

requirement, mercury concentration

and speciation, and type of existing

emission control system.

During combustion, mercury in

coal is first released as elemental

mercury (Hg0), before it is converted

to ionic or oxidized species (Hg++)

and as particulates. The conversions

depend on many factors, such as the

rate of cooling, concentrations of

halogens and sulfur trioxide (SO3),

amount of fly ash, fly ash properties

and unburned carbon in fly ash. The

concentration of elemental mercury

and ionic mercury varies from 20

percent to 80 percent, depending on

the coal, its halogen content and the

particulate mercury content. Elemen-

tal mercury is not water soluble and

is difficult to remove in downstream

flue gas desulfurization (FGD) sys-

tems. Ionic mercury, on the other

hand, is very water soluble and is eas-

ily removed in FGD systems, both

wet and dry. The particulate mercury

is also removed by devices such as an

electrostatic precipitator (ESP) or a

fabric filter (FF) with fly ash.

Mercury can be removed through

chemical adsorption on powdered

activated carbon (PAC). Activated

carbon is injected upstream of an ESP

or FF and is removed along with fly

ash. Because it is also adsorbed and

removed by PAC, the presence of SO3

adversely affects mercury removal.

If SCR is used for nitrogen oxides

(NOx) control, it can exacerbate this

problem; SCR tends to oxidize sulfur

dioxide (SO2) to SO

3 and increases

SO3 concentration in the flue gas.

Low-oxidation catalysts can be used

to minimize this problem. SO3 can

Finding Best-Fit Mercury Emission ControlsBY NAT SEKHAR, SENIOR CONSULTANT, CH2M HILL

Author

Nat Sekhar, P.E., a Se-

nior Consultant with

CH2M HILL, is an inter-

nationally recognized

emission control ex-

pert. He has been the

technical lead on more

than 25,000 emis-

sion control projects

incorporating flue gas

desulfurization, nitrous

oxide, electrostatic

precipitator/baghouse,

and other emission

control systems. Nat

has contributed to more

than 40 technical pub-

lications and presenta-

tions, and coauthored

the Fossil Fuel Power

Generation section in

McGraw Hill’s Encyclo-

pedia of Science and

Technology.

1306pe_4 4 6/4/13 3:54 PM

Page 10: Power Engineering June 2013

Founded in 1988, PIC has been a leader in the

power generation industry for over 20 years. We

are experts at managing multi-faceted projects

including start-up and commissioning, operations

and maintenance, installation, turbine outages,

mechanical services and technical services.

Combine these capabilities with our responsive

approach and global resources, and it’s easy to

see why those who know choose PIC.

25“The Best Of The Best®”

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1306pe_5 5 6/4/13 3:54 PM

Page 11: Power Engineering June 2013

www.power-eng.com6

NUCLEAR REACTIONS

years at the Summer and Vogtle construc-

tion sites, respectively. The historic com-

pletion of 7,000 cubic yards of basemat

structural concrete at each site by CB&I

(formerly Shaw Group) serves as the

foundation for the nuclear island struc-

tures, such as the reactor containment

and auxiliary buildings. Georgia Power

and SCG&E (and their co-owners) are

each building two Westinghouse AP1000

(1,100 MWe) reactors at the Vogtle and

Summer locations. Westinghouse and

CB&I are even further along in building

four AP1000 units in China.

The AP1000 is considered a third

generation (III+) advanced reactor that

provides a simplified design, reduced

capital costs, greater fuel efficiency and

enhanced safety margins through the

use of passive safety functions. There are

many other new advanced reactor de-

signs being developed, including mPow-

er’s (Babcock & Wilcox) small modular

reactor that received a DOE cost-sharing

award for certification and licensing.

Generation IV reactor designs are still

on the drawing board but have com-

mitted international partners pursuing

a defined set of approaches. Gen IV de-

signs provide even higher levels of safety

and reliability, proliferation resistance,

physical protection and economic com-

petitiveness, according to the American

Nuclear Society.

Many signs of life can be seen in the

progress made in the licensing and con-

struction of new reactor designs. Nuclear

energy may face continued economic,

technological and political challenges

but it will retain an important role in

world economic development, particu-

larly if efforts are increased to address

climate change.

With all the attention that is

being given to recent an-

nouncements of nuclear

power plant closures and threatened

shutdowns, it would be easy to think

that U.S. nuclear power is marching to

its death. Easily overlooked are the signs

of life and significant milestone achieve-

ments of new nuclear technology.

Nuclear plant owners started feeling

squeezed when decreased electricity de-

mand met a perceived natural gas glut

(much of the shale gas reserves have not

been tapped yet) and the ensuing low

prices. This combination has meant utili-

ties could get very little for their electric-

ity generation, and merchant nuclear

plants have become borderline breakeven

or worse. With the addition of costly Fu-

kushima modifications and aging major

equipment, speculation has increased

that more nuclear plants will follow the

path of Dominion’s Kewanee and Duke’s

Crystal River station.

Although it is likely that a few addi-

tional nuclear plant shutdowns will be

announced over the next year or so, po-

tential signs of life can be seen by stepping

back from the current bleak economic en-

vironment for nuclear power and looking

at the long-term prospects. According to

the U.S. Energy Information Administra-

tion (EIA), nuclear power’s share of the

electricity mix is expected to decrease by

only 2% by 2040, losing some ground

to natural gas and renewables, which

will also absorb increases in demand.

With any future regulatory effort to cap-

ture fees for carbon allowances, nuclear

power’s estimated share of generation

increases anywhere from 7-18%, taking

the gains from coal. Global long-term es-

timates show that nuclear power’s overall

proportion of electricity generation stays

fairly constant, with losses in Europe and

gains in Asia, according to the Interna-

tional Energy Agency.

The EIA predicts that by 2020 the U.S.

will become a natural gas (net) exporter,

which would put pressure on natural gas

and electricity prices and keep currently

operating nuclear power plants above

water. It is unlikely that more than a few

additional nuclear plants will close in the

U.S., given that regulated utilities will be

able to weather the current environment

and non-regulated nuclear generators

will want to retain enough nuclear ca-

pacity to be well positioned when prices

increase. Moreover, if too much nuclear

generation is lost at the same time aging

coal plants are closing, natural gas will

be used increasingly for baseload gen-

eration, putting even more pressure on

prices.

Despite economic challenges to the

nuclear industry, many experts support

nuclear power as an essential part of the

mix. At least one high-profile investor,

Microsoft Corp. Chairman Bill Gates,

touts the benefits of nuclear power and

calls for more investment in nuclear en-

ergy research. At the international energy

executives’ conference in March (CER-

AWeek), Gates endorsed nuclear power

as the best long-term solution to rising

world energy needs in the midst of cli-

mate change. Gates also discussed how

since Fukushima there is a greater de-

mand for improved reactor designs with

inherent safety features.

A significant milestone in U.S. nuclear

power was achieved very recently. In

March, South Carolina Electric and Gas

(SCG&E) and Georgia Power poured the

first new “nuclear concrete” in over 30

Nuclear Power’s Strong Future amid Challengesin the presentBY, MARY JO ROGERS, PH.D.

1306pe_6 6 6/4/13 3:54 PM

Page 12: Power Engineering June 2013

©2013 S

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Westinghouse AP1000® plant under construction in Haiyang, China

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www.westinghousenuclear.com

TECHNOLOGY

For info. http://powereng.hotims.com RS# 4

1306pe_7 7 6/4/13 3:54 PM

Page 13: Power Engineering June 2013

www.power-eng.com8

DEMAND RESPONSE

management.

Supply chain management in other

industries is the key to efficiency. That

happened when logistics specialists real-

ized that silos of activity allowed massive

inefficiencies by masking the true costs

and inconsistencies in the way goods

moved to market. Like or loathe Amazon

and Wal-Mart, that’s where most people

go when they want something quickly

and at the lowest cost. In other words,

the market demanded and the suppliers

responded.

That is the key to understanding DR. It

is supply chain management, and we’d

be well advised to learn to do this well.

Today’s customers want green, reliable,

efficient, safe, and productive power.

Economic productivity and climate sus-

tainability demand it.

In coordinated communities, peaks in

one section can fill valleys in another. En-

ergy storage, EV charging and distributed

generation are in the mix. Perhaps the

future of Integrated Resource Planning

should include “Energy Districts” that

self-optimize and present a “flattened”

profile to the larger grid. Maybe the util-

ity of the future should develop, own and

operate those resources. They are expert

as asset and financial management.

Clearly, the US has not scratched the

surface of efficiency once we get outside

the thinking that it must be specific to a

customer facility. Efficiency is environ-

mental, but DR is management. It can

shape, tune and arrange energy use to

respond to opportunities. My father al-

ways said to learn a tool well, but then to

use the right tool for the job. With respect

to efficiency in the US, so far we’ve been

using hammers for everything. Enough.

The Department of Energy de-

fines Demand Response (DR)

as “changes in electric usage by

end-use customers from their normal

consumption patterns in response to

changes in the price of electricity over

time, or to incentive payments designed

to induce lower electricity use at times

of high wholesale market prices or when

system reliability is jeopardized.” The

2005 Energy Policy Act encourages the

use of Demand Response and FERC has

manifested this in a number of tariffs

which grant equivalency between DR

and generation in value. But…

What is Demand Response, really?

Electrons obey the laws of physics. They

travel to ground over the path of least re-

sistance. Our job is to get them to do a lit-

tle work along the way without wreaking

too much havoc, which they like to do.

Demand response is how we do that.

Everything about an electron’s intended

journey to ground is shaped by some-

one’s desire (“demand”) to achieve a goal.

Those goals are determined by the com-

munity of electron users; i.e., customers.

They demand power: clean, abundant,

cheap, renewable, and efficient. In that

sense, DR is everything a utility does.

Now is the time to use DR to meet

goals of efficiency and environmental

stewardship.

Thirty-one states have renewable en-

ergy portfolio standards. Too few of them

allow energy efficiency to count toward

those goals. If less energy is needed, then

it’s simple math that each source of that

energy can contribute a larger percent.

Similarly, DR is vital both in making re-

newable electrons behave as well as tim-

ing demand so that it peaks when those

renewable electrons are most available.

It is precisely this attribute that leads the

California Independent System Operator

(ISO) to predict that by 2020, the tradi-

tional fossil fuel supplied afternoon de-

mand peaks will disappear. Local solar

and other techniques will move peaks to

early evening.

That is a sea change in the way we

think about grid planning.

There is a form of Demand Response in

commercial production that is analogous to

most forms of generation, except perhaps

for black-start, but don’t rule that out.

Realistically, generation is always neces-

sary, since DR only can free, not generate,

electrons. Even that is subject to revision

as local solar, batteries and other forms

of distributed generation begin to assert

themselves on the demand side, respond-

ing not only to site needs but also to larg-

er microgrid and macro-grid conditions.

For two years, Massachusetts has been

the most energy efficient state. Utilities

there have done about all the efficient

lighting, weather-stripping, rebating and

retrofitting they know how to do. Yet, the

legislature demands more. The answer

may be to leave the customer site and

take the larger view; to examine what we

mean by “efficiency”.

The most efficient grid is a steady

state grid where demand and supply stay

constant and balanced. The rhythms of

life prevent that perfect state, but we are

well short of what we can do. Local dis-

tributed renewable and efficient electric

generation, coupled with intelligent and

efficient control and use can flatten ex-

isting demand curves, but it means that

Demand Response must be synonymous

with supply chain management. Huh?

If an electron is the product, then every-

thing that happens to it is supply chain

Demand Response Invades the Grid and Makes it SmartBY PHIL DAVIS, SENIOR MANAGER SMART GRID SOLUTIONS, SCHNEIDER ELECTRIC

1306pe_8 8 6/4/13 3:54 PM

Page 14: Power Engineering June 2013

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Page 15: Power Engineering June 2013

www.power-eng.com10

VIEW ON RENEWABLES

Elements ofSuccess in Tidal Energy DevelopmentBY JOHN M. FERLAND, OCEAN RENEWABLE POWER

fishermen, who helped ORPC site the

Cobscook Bay Project, resulting in a

location that met our requirements

while minimizing disturbance to

fishing activities.

ORPC has also benefitted from the

availability of local divers and com-

mercial vessel operators and crews

for support on environmental stud-

ies and Project construction, opera-

tions and maintenance. The Eastport

Port Authority was key in the Project’s

cable laying operations and has pro-

vided a range of services throughout

ORPC’s seven years working in the

area.

When ORPC initiated a marine

mammal observation program to

meet our licensing requirements,

professional fishermen, a local kayak

guide, a whale watch operator, and

others familiar with local waters re-

sponded. Following professional

training as observers, they joined our

operations team during the Project’s

initial construction phase, and will

continue to work with us as the proj-

ect build-out continues.

Local support for ORPC has helped

us create a strong economic footprint

statewide. Since 2007 we have spent

more than $21 million throughout

Maine, supported more than 100 jobs

statewide, and established a supply

chain reaching 13 of the state’s 16

counties.

The promise of economic growth

was a major reason why Maine imple-

mented the Ocean Energy Act in 2010.

The Act created regulatory reform

for small-scale tidal energy projects

and the opportunity for a long-term

In 2012 Ocean Renewable Power

Company (ORPC) began oper-

ating the first federally licensed,

commercial, grid-connected tidal en-

ergy project. Situated on the U.S. side

of the Bay of Fundy, the Cobscook

Bay Tidal Energy Project is the only

ocean energy project, except for one

involving a dam, that delivers power

to a utility grid in the Americas. The

Project benefits from having the first

long-term power purchase agreement

for tidal energy issued in the U.S., al-

lowing us to expand to up to 5 MW of

production.

As a first mover in an emerging

industry, ORPC has had to address

complexities related to technology

development, resource assessment,

project siting, marine construction,

regulatory requirements, environ-

mental monitoring and public policy.

Key to project success has been the

positive relationships ORPC has de-

veloped with host communities and

regulators. This facet of project devel-

opment is core to our company.

Through early, open and frequent

communications, ORPC developed

relationships and built trust with the

host communities of Eastport and

Lubec, Maine. Their economies and

ways of life have historically been

defined by the success of their ma-

rine industries. The local workforce

is highly skilled in marine operations

and has provided us with guidance

and expertise needed to work in lo-

cal waters. Strong relationships have

been established with the Eastport

Port Authority, local harbor pilots,

and most importantly, commercial

power purchase agreement through

the Maine Public Utilities Commis-

sion.. Additionally, Maine and the

Federal Energy Regulatory Commis-

sion (FERC) signed a Memorandum

of Understanding pledging to align

state and federal approaches to tidal

energy regulation.

ORPC has forged productive rela-

tionships with state and federal regu-

latory agencies. We recently submitted

the Project’s first annual environmen-

tal monitoring report to FERC. The

agency requires licensees to develop

adaptive management plans for evalu-

ating environmental monitoring data

and making science-based decisions

to modify monitoring as necessary.

The goal is to maintain levels of mon-

itoring proportional to project risk

through a collaborative effort with

regulatory agencies and key advisors

who comprise the adaptive manage-

ment team. Results to date indicate no

observed, adverse interaction of the

TidGen® Power System with the ma-

rine environment. We appreciate the

regulatory resource agency members

of our adaptive management team

for their guidance, and because of it,

ORPC is at the forefront of innovative

environmental monitoring efforts for

tidal energy projects.

Many challenges remain for the

tidal energy industry. Time will tell if

our experience in Maine can be repli-

cated in other jurisdictions. At a min-

imum, ORPC’s experience provides

examples of the types of community,

public policy and regulatory dynam-

ics that are necessary for a tidal energy

project to evolve successfully.

Author

John M. Ferland is

Vice President of

Project Development

for Ocean Renew-

able Power Compa-

ny, an international

industry leading

developer of tech-

nology and projects

that generate clean,

predictable power

from ocean and

river currents. He

leads the company’s

project develop-

ment, environmental

permitting and

project licensing ac-

tivities. John draws

on over 30 years of

experience in com-

mercialization strat-

egy for renewable

energy companies,

port emergency re-

sponse operations,

coastal resources

management, and

public policy.

1306pe_10 10 6/4/13 3:54 PM

Page 16: Power Engineering June 2013

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Page 17: Power Engineering June 2013

www.power-eng.com12

GAS GENERATION

POTENTIAL PRICE VOLATILITY

Although the industry has prepared for

increasing prices, there is concern about

the volatility of the pricing of natural gas.

Unlike other power generating fuels such

as coal, natural gas can be used by mul-

tiple industries for a variety of reasons.

“There are a lot of petrochemical re-

fineries and others that can use natural

gas, and you could potentially increase

demand quite a bit,” Thomas said.

As Thomas pointed it, it wasn’t long

ago that natural gas prices were in the

double-digit range, and it’s possible that

could happen again.

When companies are spending hun-

dreds of millions to build a power plant,

uncertainty is a concern, and price vola-

tility is an area being monitored.

EPA CONCERNS

The area of most uncertainty for the in-

dustry isn’t pricing, however. It’s the U.S.

Environmental Protection Agency.

Thomas said a long-term strategy with

the current uncertainty and regulatory

structure is “almost an oxymoron” be-

cause of changing regulations.

The EPA has recently revised rules,

such as the Mercury and Air Toxics Stan-

dards, or failed to finalize rules, such as

the New Source Performance Standard.

Any time a company is planning an in-

vestment that could cost up to $1 billion,

it needs as much information as possible.

With the current climate of rules chang-

ing, important information just isn’t

available right now.

ADVANTAGES

OF NATURAL GAS

Despite potential price volatility and

regulatory uncertainty, natural gas-fired

plants have many benefits. Several of the

executives noted the lower costs to build

Recently, I had the opportunity

to moderate a discussion about

natural gas-fired generation be-

tween executives from Alstom, Ameri-

can electric Power, Bechtel and Electric

Power Research Institute. The result was

a fast-paced conversation that brought up

many issues the industry is currently fac-

ing. The discussion was published in the

May issue of Power Engineering.

Here are a few key points that came out

of that discussion.

PREPARED FOR

HIGHER PRICES

Although recent increases in natural

gas prices have created media head-

lines, people in the industry have been

expecting prices to increase and are

prepared for it.

Scott Austin, manager of business

development for Bechtel’s thermal

business line, said that gas-fired power

generation would still be the fuel of

choice over the mid-term with prices

staying in the $5 to $7 MMBtu range,

with significant opportunities for new

builds in the next two years.

Pricing will affect how plants are oper-

ated, however. AEP Vice President of Gen-

erating Assets Toby Thomas said at higher

prices, natural gas-fired plants would be

cycled more often, while plants would be

more likely to run at base load constantly

when gas is in the $2 MMBtu range.

Recent reports from the U.S. Energy

Information Administration support

Thomas’ statement. As gas prices have

increased from a Henry Hub price of

$1.99 MMBtu on April 25, 2012, natural

gas-fired power generation has also de-

creased, producing around 32 percent of

the electricity in the U.S. in April last year.

That compares to 25 percent in March of

this year.

the plant – usually half of the price of a

coal-fired power plant and one-third of

a nuclear plant – and the quick dispatch

time that allows a plant to be at 50 per-

cent of its capacity in 10 minutes.

Operational costs are also lower as

fewer employees are needed at a natural

gas-fired plant and the fuel is brought

in through a transmission line and not

manually loaded.

Gas also burns cleaner than coal, and

most modern combined-cycle plants

would have met the NSPS regulation

without any additional costs.

NOT THE ONLY OPTION

Despite the advantages of gas, every

executive participating had concerns the

industry could become too reliant on it as

a fuel source for power generation.

“Gas is just an easy decision, and it re-

ally concerns me that the industry doesn’t

have the flexibility to provide more diver-

sity,” EPRI Vice President of Generation

Tom Alley said, who also noted the in-

dustry is being led toward natural gas as a

“destination” fuel source.”

Overreliance on natural gas could

strain the transmission system, causing

potential risks to grid reliability. To en-

sure reliability, companies need a diver-

sified energy portfolio – but the options

available for more diversity are currently

unclear.

Alstom Vice President – Gas Product

Platform Amy Ericson said “it’s pretty

scary out there” for the company’s cus-

tomers, who don’t know whether they

can count on nuclear license renewals

or plan for coal-fired generation with-

out carbon capture and storage tech-

nology. At the same time, she said, “the

prospect of only gas and renewable is

probably not the best choice” for the

industry or the U.S.

Natural Gas Execs DiscussIndustry Trends, ConcernsBY JUSTIN MARTINO, ASSOCIATE EDITOR

1306pe_12 12 6/4/13 3:54 PM

Page 18: Power Engineering June 2013

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1306pe_13 13 6/4/13 3:54 PM

Page 19: Power Engineering June 2013

www.power-eng.com14

POWER PLANT PROFILE

bringing a new coal plant online in the

late 2000s was never going to be easy. “I

would think there was always some con-

cern,” said Tim Riordan, vice president of

engineering services for AEP, “because

much of this was going to have to be de-

cided in the court system or with com-

missions or other federal agencies and of

course we don’t have control over that.”

Still, it wasn’t just a regulatory victory

when the plant finally went into service

on December 20, 2012. The event was

BY DENVER NICKS, ASSOCIATE EDITOR

Firsts are rare—by defi-

nition they come only

once—and lasts are rare

for the same reason. But

rarest of all is that which

is the first and last of its kind, like

Doctor Frankenstein’s hero-monster,

doomed to be forever alone on the

day it was born. AEP’s ultra-supercrit-

ical coal-fired Turk power plant may

prove to be one such rarity: a great

technological leap forward unlikely to

ever be repeated again in the United

States.

The Turk project was announced in

August 2006 but didn’t go online until

seven years later. AEP spent those inter-

vening years securing the necessary regu-

latory permits and fighting a battle in the

Arkansas Supreme Court. AEP ultimately

lost that battle, requiring a late-in-the-

game reconfiguration of where all the

plant’s power output would be sold, but

1306pe_14 14 6/4/13 3:54 PM

Page 20: Power Engineering June 2013

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also a technological victory: AEP had suc-

ceeded in bringing online the most effi-

cient coal-fired commercial power plant

ever built.

The 600 MW Turk Power Plant

is situated in Hempstead County, in the

southwestern corner of Arkansas, where

it employs 109 people on a total payroll

of $9 million and pumps $6 million in

school and county property tax revenues

every year, according to AEP. Through

its subsidiary the Southwestern Electric

AEP’s Turk is one of the most efficient, least polluting coal-fired power plants on the planet.

“This could very well be one of the last conventional coal burning facilities built in the country.” - Tim Riordan, AEP

Power Co., or SWEPCO,

which operates the facility,

AEP invested $1.3 billion

of the $1.8 billion required

to build the plant and the

company now owns 73

percent of its output. The

remaining ownership is

divided between the Arkansas Electric

Cooperative Corp.,

the East Texas Elec-

tric Cooperative,

and the Oklahoma

Municipal Power

Authority.

The at-

tribute that makes

Turk unique among power plants—that

gives cause to append the word “ultra”

to the preexisting and more familiar

“supercritical”—is that it works just like

a supercritical power plant, only better.

As an ultra-supercritical coal-fired power

plant, Turk operates at extraordinarily

high pressures and temperatures, well

above typical supercritical pressures of

around 4,500 psi and hotter than 1050

degrees Fahrenheit.

“As you increase temperature you

increase your ef-

ficiencies,” Rior-

dan explained. By

working at such a

high temperature

and pressure, Turk

achieves the high-

est efficiencies

around in coal power generation today;

according to AEP, between 39 and 40

percent of the thermal energy available

1306pe_15 15 6/4/13 3:54 PM

Page 21: Power Engineering June 2013

www.power-eng.com16

tested to withstand the pressure and tem-

perature of an ultra-supercritical power

plant. For use in the facility materials

need to have high creep rupture strength,

resistance against embrittlement, and

low oxidation growth in addition to ease

of manufacture and availability. “High

chrome, creep strength enhanced ferritic

steels (CSEF), and nickel based alloys

meet these needs,” Riordan said.

Working with both the original equip-

ment manufacturers and with EPRI (the

Electric Power Research Institute), and

other research groups, AEP worked “to

understand these components”—like

boiler headers, main steam lines, and

blade components—“for their weldabili-

ty and long term creep strength,” Riordan

said. “There was quite a bit of R&D work.”

In constructing Turk, AEP bought

the major components, like the boiler

turbine and environmental control

equipment, before its EPC agreement

like catalytic reduction systems, dry flue

gas desulfurization, baghouse technol-

ogy to combat particulate releases and

activated carbon injection to reduce Hg

emissions. The end result is one of the

most efficient, least polluting coal-fired

power plants on the planet.

Achieving super-high temperatures

and pressures wasn’t as easy as just dialing

up the heat. Special materials had to be

in the fuel comes out as electric power.

This level of efficiency in extracting en-

ergy from coal allows Turk to use less of

the stuff to produce the same amount

of power. Less coal burned means less

emissions of sulfur dioxide, nitrogen

oxide, mercury, carbon dioxide and

particulate matter. It also means fewer

waste products and less fly ash, and de-

creased need for the commodities used

in environmental control activities, like

activated carbon and ammonia. The re-

duction in pollutants is combined with

the latest emission-control technologies,

Joey White, machinist, works to move some of the Turk Plant’s emissions control equipment into place.

Drew Smith, machinist, performs maintenance on oneof the Turk Plant’s six coal pulverizers.

1306pe_16 16 6/4/13 3:54 PM

Page 22: Power Engineering June 2013

www.power-eng.com 17

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with Shaw was completed. Afterwards,

however, Shaw led construction on

everything but the boiler, in addition

to completing engineering details and

integration of the facility. The boiler,

along with the baghouse, dry scrub-

ber, and selective catalytic reduction

unit, were all provided by Babcock &

Wilcox, while Alstom provided the

main turbine and generator in addi-

tion to the feed pump turbine.

In designing and constructing Turk,

AEP included input from operating

staff to ensure the innovative facility

didn’t just make sense from an eco-

nomic and regulatory perspective, but

from an ergonomical perspective too.

Design plans gave consideration to

something as simple as making sure

that headroom was sufficient to safely

remove motors or maintain equip-

ment. “Many times with an EPC con-

tract the footprints get smaller and

smaller because of cost concerns,”

Riordan said. “We spent a lot of time

with our engineer of record, Shaw, to

make sure that we had a very safe and

maintainable facility.

“You really don’t want people stand-

ing on hand rails to operate a valve,

right?”

As to whether or not there will ever

be another American plant like Turk,

Riordan isn’t optimistic.

“I would hope so. Unfortunately

with the new environmental rules for

new generating facilities, the proposed

CO2 limits are probably going to pre-

vent that from happening in the near

term,” he said.

“This could very well be one of the

last conventional coal burning facili-

ties built in the country.”

1306pe_17 17 6/4/13 3:55 PM

Page 23: Power Engineering June 2013

www.power-eng.com18

WHAT WORKS

solution with a machine which is simi-

lar to a swimming pool pump. After

four hours of cleaning, his team checks

the condition of the tubes. “If it needs

more, then we’ll use a slightly stronger

solution and circulate it for another two

hours or so,” he said.

Conklin said the cleaning method is

very safe.

“We keep the chemical solution in

the tube bundle and circulate it from

there to our cleaning equipment,” he

said. “It’s cut off from all the other

equipment, so there’s no contamina-

tion – no safety issue.”

The formula includes corrosion in-

hibitors and is approved for use on steel,

iron, brass, copper, plastic and rubber.

Specially formulated ScaleBreak-SS is

safe for stainless steel.

Augusta Industrial Services reports

that chemical cleaning is economical.

Conklin said that’s because circulating

the chemicals is a much faster method

than standard manual cleaning.

After the first thorough cleaning,

subsequent visits often take less time.

“Next time we come out we might cut

the time in half – it could take only

two hours of descaling to clean every-

thing,” he says.

ScaleBreak does not con tain toxic

cresols or other tar oils that need

SARA Title III, Section 313 spill loss

or disposal reporting. The waste prod-

uct is mildly acidic and contains only

nontoxic salts after being used to re-

move potable water scale. It rinses eas-

ily with water and requires no special

equipment for handling.

Conklin also likes that chemical

cleaning can take less of a toll on his

crew. Mechanical cleaning and hydro-

blasting are physically taxing methods,

and fatigue can contribute to accidents.

ScaleBreak’s formulation makes it a safe

choice for service personnel, since they

don’t have to deal with caustic chemi-

cals or noxious fumes.

About two years ago, a power plant

in Georgia pulled covers to in-

spect eight of their A/C chillers

and found that they showed substantial

scale buildup on the inner surfaces of the

tubes, the outer surfaces and the tube

facings. The buildup resisted the facil-

ity’s standard mechanical cleaning pro-

cedures. The tubes’ inner diameters were

narrowed to the point where adequately

sized cleaning brushes could not be in-

serted into the tubes.

The power company asked Augusta

Industrial Services, Inc., which services

nuclear power plants throughout the

southeastern United States, to help find

a solution. Augusta Industrial Services,

based in Augusta, Georgia, visited the

plant to investigate the situation.

“The tube bundles were so bad –

fouled with scale and grit – that you

couldn’t put the correct brush in the

chiller to clean it. Therefore the regular

mechanical cleaning method was out

of the question,” explains Augusta’s

supervisor Shawn Conklin.

Often power plants will allow the

chiller tubes to be cleaned by hydro

blasting, but that method was not an

option in this situation. “The number

one concern is safety, and with the pos-

sibility of puncturing a tube by hydro

blasting, the plant’s engineers would

not allow us to use high pressure water

on these chillers,” said Conklin.

The power company asked Augusta

Industrial Services to find a chemical

cleaning solution for clearing out the

tubes. Two of Augusta’s on site supervi-

sors (Shawn Conklin and Taylor Smoot)

conducted its research. After consider-

ing the alternatives and discussing them

with the plant’s engineers, they received

approval to call Goodway Technologies

Corp. to request a sample of the chemi-

cal ScaleBreak for testing. All involved

parties liked that the independent studies

showed that ScaleBreak dissolves calcium

deposits, rust, lime and lithium carbon-

ate on contact without damaging the

equipment being serviced.

Augusta Industrial Services test-clean-

ing consisted of several chunks of the

deposit, that was scrapped off of the tube

face, being placed into a beaker and then

adding a capful of the ScaleBreak at a

time until the pieces started to.

As the test-cleaning satisfied the en-

gineering staff, the Augusta supervisors

were given the approval to proceed with

an initial order of ScaleBreak and the

cleaning of one unit.

“Actually, the first time we cleaned it

we mixed it wrong – we were told the unit

capacity was 400 gallons, but it was re-

ally 700 gallons, so our mixture was too

weak. Even so, it was already starting to

remove some scale,” said Conklin. “So we

had more ScaleBreak shipped to us over-

night. We got the calculations right, circu-

lated it for four hours, drained it, rinsed it,

and we just couldn’t believe how clean it

was – we were really surprised.” Conklin’s

crew ordered more ScaleBreak and took

care of the other seven chillers without

any difficulties.

Conklin explains how the process

works. “We calculate the tube bundle’s

volume – anywhere between 150 gal-

lons to 1,000 gallons – then we calcu-

late how much ScaleBreak versus wa-

ter to use. Right now we like to use a

60-40 mixture – 60 percent ScaleBreak

and 40 percent water. That works out

really well for us.” Conklin continues.

Conklin said they circulate the

Dealing with Scale BuildupBY SANDI HAGUE, HAGUEDIRECT LLC

1306pe_18 18 6/4/13 3:55 PM

Page 24: Power Engineering June 2013

348 Circuit Street

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1306pe_19 19 6/4/13 3:55 PM

Page 26: Power Engineering June 2013

www.power-eng.com 21

risk of prematurely converting a plant

to natural gas and facing the unafford-

able cost to convert back if the price

and availability of natural gas becomes

uneconomical. These choices have sig-

nificant impact on the plant’s opera-

tional costs and the economy.

An alternative to avoid these issues is

to use Dry sorbent injection (DSI). Dry

sorbent injection is a pollution con-

trol technology that plays a role in the

U.S. power sector’s compliance with

the Mercury and Air Toxics Standard

(MATS). The Environmental Protec-

tion Agency (EPA) finalized the MATS

rule in December 2011. The MATS rule

requires that all U.S. coal- and oil-fired

power plants greater than 25 mega-

watts meet emission limits consistent

with the average performance of the

top 12 percent of existing units, known

as the maximum achievable control

Extending the Life of COAL FIRED PLANTS

BY STEVE COULOMBE, PRODUCT MANAGER FOR DSI MILLS AT STURTEVANT

Operators of coal fired

power plants have a

lot to worry about

today: The price of

coal relative to natu-

ral gas, stack emissions, EPA regula-

tions and the unpredictable nature of

future potential regulations. With an

uncertain future, one question hangs

in the balance: is it economical to

maintain a coal fired power plant and

reduce its stack emissions?

This tough question is driving trends

towards plant upgrades, early plant re-

tirement and conversion to natural gas

as solutions to control pollution. Pro-

ducers of coal fired power are experi-

encing two hidden costs to early plant

retirement or conversion which are

important to understand. The first is

the unpredictability of the future cost

of natural gas and the second is the

The Sturtevant DSI pin mill reduces sorbent to a fine

particle size, which is used to lower emissions of sulfur

dioxide, sulfur trioxide and hydrogen chloride. Photo

courtesy of Sturtevant

Dry SorbentInjection

through the use of

1306pe_21 21 6/4/13 4:02 PM

Page 27: Power Engineering June 2013

www.power-eng.com22

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• Dissolve calcium, lime, rust, lithium carbonate and more

• Increases system efficiency • Safe for use on steel, iron, brass,

copper, plastic and rubber• Special formulation available for

use on stainless steel• Use on power plant surface

condensers, boilers, chillers, heat exchangers, and more

Goodway ScaleBreak® removes tough scale build-up quickly, safely and easily.

DE-SCALEWITHOUT FAIL.

(SO2) or sulfur trioxide (SO3) emis-

sions through the same process as HCl

removal. While the MATS rule does not

specifically address SO2 or SO3, it has

similar qualities to HCl and other acid

gases that enable it to respond simi-

larly in a DSI system. SO2 and SO3 are

also regulated under the Cross State

Air Pollution Rule (CSAPR). There-

fore, installing a DSI system to comply

with MATS will also help plants meet

or even exceed their CSAPR emission

limits.

THE APPLICATION OF

A MILL IN PROCESSING

SORBENTS FOR DSI

Dry Sorbent Injection, is part of

a Flue Gas Desulfurization system

(FGD), capable of SO2 and SO3

mitigation, as well as HCl, and mer-

cury removal depending on sorbent

technology (MACT). The rule applies

to three pollutants: mercury (Hg), hy-

drochloric acid (HCl), and filterable

particulate matter (fPM) and has a

compliance deadline in 2015 (with op-

portunities for additional compliance

time depending upon case-by-case

circumstances). While DSI systems do

not control mercury, they can, when

combined with a particulate control

filter, meet this standard for two of the

three controlled pollutants.

DSI systems remove hydrogen chlo-

ride (HCl) and other acid gases like

SO2 and SO3, through two basic steps.

Step one. A powdered alka-

line sorbent is injected into the flue

gas (combustion exhaust gas exiting

a power plant) where it reacts with

the HCl and SOx. The sorbents most

commonly associated with DSI are

trona (sodium sesquicarbonate, a

naturally occurring mineral mined in

Wyoming), sodium bicarbonate, and

hydrated lime.

Step two. The compound

formed by the alkaline sorbent and the

acidic gas is removed by a downstream

particulate matter control device such

as an electrostatic precipitator (ESP) or

a fabric filter (FF), also referred to as

a bag house. Testing has demonstrated

that fabric filters are more effective

(when combined with DSI) than ESPs,

with respect to overall HCl and SOx

reduction. For modeling purposes,

the EPA estimates a DSI system with a

fabric filter is expected to achieve 90%

removal of HCl, while an ESP only

achieves 60 percent removal, although

actual performance will vary by indi-

vidual plant.

As mentioned, DSI systems can also

significantly reduce sulfur dioxide

1306pe_22 22 6/4/13 4:02 PM

Page 28: Power Engineering June 2013

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1306pe_23 23 6/4/13 4:02 PM

Page 29: Power Engineering June 2013

www.power-eng.com24

and state regulations, considering a

DSI and mill can bring a plant quickly

into a safe condition to comply cost

effectively while still keeping all

options open to future alternative fuel

choices. Operators have found that

relieving the pressure of making an

early conversion decision, potentially

pre-maturely, will save significant

money and jobs for plant facilities

due to less closures while meeting

the future energy demands of the

community.

DSI with mill systems can be

pre-tested by engineering firms

specializing in DSI installations and

has proven its effectiveness over the

last 10 years throughout the U.S.A.

Milled DSI systems have been

installed for over twelve years and

maintain constant operation. These

mills are specially designed to meet

both the rigors of DSI and the needs

of the power generation community.

It is important to understand that

general, commercially available mills,

are designed for many applications.

These applications do not necessarily

reflect the needs of power generators.

The typical system installed for DSI

selections. DSI treatment for mercury

removal is similar to other forms of

FGD but uses either powder activated

carbon reactant or Amended Silicates,

a patented process for mercury remov-

al. Formed particulate is then captured

in the same way that other DSI systems

capture their reacted compounds as

described above. When investigating

the use of a DSI system the first con-

sideration is typically the cost to oper-

ate the system. A DSI system has a far

less cost to operate and install than a

wet scrubber system

for power plants, in-

dustrial boilers, in-

cinerators or co-fired

plants that are only

partially converting

to natural gas fired,

or undecided to con-

vert, or may want to

fire oil or coal for 5 or

more years. Research has shown that

the capital and installation costs to op-

erate a DSI system are only 10 percent

on average, compared to that of a wet

scrubber system.

SOx is mitigated most effectively

by alkaline type sorbents like Trona

and Sodium Bicarbonate (SBC),

although hydrated lime or limestone,

if locally obtained, can be a viable

solution. SBC must be milled (ground

finer), and Trona should be milled

for maximum effect. The purposed of

milling is both to reduce the amount

of sorbent consumed by the system

and increase the sorbent surface area

which increases the availability of a

reactive particle surface. As SO3 is

eliminated, blue plumes from sulfuric

acid disappear, boilers run more

efficient, system

corrosion is lowered

and mercury can be

removed more easily.

A variety of sorbents

can be blended,

as supplied to the

on-site mill before

DSI, or milled and

injected separately if

optimum injection points need to be

considered. SO2 removal to levels of

95 percent can help control acid rain

and is also a good reason to consider a

DSI system with milling.

With the advent of the MATS and the

ongoing EPA rule changes, litigation

Research has shown that the capital and installation costs to operate a DSI system are only 10% on average.

The Ghent Generating Station is a coal-fired power plant owned and operated by Kentucky Utilities near

Carrollton, Ky. Dry sorbent injection systems were installed to comply with new federal emission standards.

A Trona mill system led to a 30 percent decrease in sorbent usage. Photo courtesy of Sturtevant

1306pe_24 24 6/4/13 4:02 PM

Page 30: Power Engineering June 2013

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Page 31: Power Engineering June 2013

www.power-eng.com26

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will be installed in an out-building

with no temperature control and must

be operated 24/7 with minimum down

time or cleaning time. Manufacturers

have designed unique features to these

mills to make them suitable for DSI.

Some typical features include rotating

round pin sections to minimize the

wear caused by milling naturally

occurring minerals which have abrasive

properties, special metal coatings which

also minimize wear and pre-heating

and cooling systems for plants operating

in ambient temperatures below 40F or

above 90F. An important consideration

in DSI systems is designing for use of

these specific-duty pin mills. .

The benefit of using a pin mill is in its

ability to offer the smallest particle sizes

to increase the reactive surface area and

help the plant consume less sorbent. A

pin mill for DSI operates by blowing

sorbent into the top of the mill using

a pneumatic conveying system. The

sorbent then enters the mill where one

rotor with a set of pins rotates between

a second, stationary rotor. The sorbent

works itself through pressure and force

from the inside of the rotor to the outside

of the rotor where the action of the pins

reduces the particle size. Fine particles

exit the outer edge of the rotor where

they are then blown into the process

to be added to back to the DSI system

for injection. This simple process is the

heart of DSI systems as it is responsible

for controlling the effectiveness of the

removal of gasses from the system.

Particle size reduction has a key role

in FGD and understanding the part

sorbent milling plays in trona systems

is the best example.

A typical example of DSI is the use of

milled trona. Supplier-delivered trona

with a particle distribution where 50

percent of the particle size is 30μm or less

(referred to as d50) has an average per-

particle surface area of about 2,800μm2.

The advantage of operating a DSI system

is by reducing ongoing operating costs.

This is where the pin mill plays its key

role. A pin mill is capable of reducing

the d50 from 30μm to 7μm which, in

a single particle, is the equivalent of

reducing a dust particle to the size of a

red blood cell. This reduction in size

has an exponential impact on particle

surface area by volume, increasing the

reactive surface area from about 4,000in2

to 20,000in2 for equivalent mass.

When considering the future of coal-

and oil-fired power, alternatives to

conversion and early retirement exist.

DSI is affordable, compliant and easy to

operate and should be considered when

planning the future of any plant.

1306pe_26 26 6/4/13 4:02 PM

Page 32: Power Engineering June 2013

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1306pe_27 27 6/4/13 4:02 PM

Page 33: Power Engineering June 2013

www.power-eng.com28

Nearly 50 years ago,

Norm Harty, presi-

dent of N.B. Harty

General Contrac-

tors Inc., was a

driller and dynamite blaster for road

and railway construction when Ken-

neth Bridegroom, a supervisor at a

power plant where Harty was subcon-

tracting, asked if dynamite could be

used to clean the inside of a boiler.

“Back then I was hungry,” Harty

BY JUSTIN MARTINO, ASSOCIATE EDITOR

said. “I was really, really searching for

anything.”

Although Harty had never seen the

inside of a power plant before, he told

Bridegroom he could do the job. Af-

ter a labor strike and a buildup of slag

prompted the plant to contact Harty,

he used dynamite to remove a slag de-

posit, inventing the process as he went

along.

“I didn’t really realize exactly what

I had done, but Bridegroom did,” he

If slag is allowed to build up inside a boiler, it can lead not

only to efficiency problems but can also cause damage

because of the weight. Photo courtesy of Norm Harty.

said. “The rest is history. The next

thing I knew I was going all over the

east doing this, and it was all by word

of mouth.”

Harty used his technique for 17

years before he had any competitors

attempting to use the same process.

Using dynamite is still an option for

power plants, and Harty’s company

cleans nearly 100 boilers a year.

Other operators are looking at differ-

ent methods that have been developed

1306pe_28 28 6/4/13 4:02 PM

Page 34: Power Engineering June 2013

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For info. http://powereng.hotims.com RS# 17

1306pe_29 29 6/4/13 4:02 PM

Page 35: Power Engineering June 2013

www.power-eng.com30

because less fuel is needed to produce

the same amount of power, according

to Tim Martin, Director of Product

Management for Clyde Bergemann

Power Group Americas Inc., Boiler Ef-

ficiency Division.

FUEL SWITCHES LEADING

TO SLAG DEPOSITS

Slag deposits can be caused by mul-

tiple sources. Harty said older boilers,

especially in the eastern U.S., were

much smaller because the plants were

burning high-sulfur eastern coal with

a high Btu output. Less fuel was need-

ed to produce the required heat, and

the boilers did not produce as much

ash.

The high-sulfur coal released more

maintenance, Harty said.

Dirty boiler tubes can also affect

the operation of a plant. Slag buildup

on tubes will act as an insulation pro-

tecting the tube from the heat of the

boiler, requiring more fuel to reach

the same temperature and produce the

same output as a clean boiler. Harty

said cleaning the slag deposits inside

a boiler can increase boiler efficiency

from 1 percent to 4 percent.

“Even 2 to 3 percent in a boiler that

generates 600 MW, that’s hundreds

of thousands of dollars each day or

week,” he said. “They’re still burning

the coal, but the coal fire doesn’t get to

the tube.”

Clean boilers can also help reduce

the emissions produced by the plant

to clean boiler tubes without taking

the plant offline, including improving

the soot blowers located in the boiler.

Whichever methods is chosen, howev-

er, the importance of keeping a clean

boiler is not in question.

THE IMPORTANCE OF

BOILER TUBE CLEANING

Power plants burning anything

other than natural gas will, over time,

build up ash that forms slag deposits

on the exterior of the tubes running

through the boiler. The slag can be a

safety hazard – the tubes expand and

contract as they heat up and cool down

and the deposits may break off and

fall, a problem that arises most nota-

bly when a plant is taken offline for

Norm Harty has been using explosives to clean boilers for

nearly 50 years, which helps increase boiler efficiency and

heat transfer. Photo courtesy of Norm Harty.

1306pe_30 30 6/4/13 4:03 PM

Page 36: Power Engineering June 2013

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Page 37: Power Engineering June 2013

www.power-eng.com32

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cleaning the boilers have changed.

Although coal plants previous ran at

full load as much as

possible, the drop

in price of natural

gas has caused many

owners to cycle the

plants more so that

they’re not always

running at full load.

“It’s been a huge

change in the way

the coal plants are operated,” Booher

said. “Not only is natural gas at record

lows, which causes coal plants to be

dispatched lower, but there’s also ex-

tensive renewables online now. So in a

place like Texas, where many large coal

plants are designed to run full load,

these are now up and down on load.”

Harty said that bringing the boiler

pollutants into the air, so plants be-

gan using western coal, such as Pow-

der River Basin coal, in their fuel mix.

Western coals create more ash and

produces less Btus, requiring more fuel

for the same temperature. Plants that

burn lignite, often located along the

Missouri River, require even more fuel.

Those boilers might be twice as large as

a Midwest plant built to burn western

coal and three or four times as large as

plants built to burn eastern coal, many

of which are being decommissioned

right now, Harty said.

Fuel switches can create a problem

in a plant. If more ash is produced than

the plant’s current system can handle,

the slag buildup can become uncon-

trollable over time. This can happen

when units are burning Powder River

Basin coals or other coals that have

low melting points for the ash or sig-

nificant sodium levels, which makes

the ash more tena-

cious in areas such as

the convection pass,

said Joel Booher, a

business manager for

Diamond Power.

“Unless the fur-

nace box is very

large, what you’ll see

is the boiler eventu-

ally can’t take it anymore, and you’ll

have uncontrollable slag formation,”

Booher said. “That was what we were

fighting against.”

CHANGES IN THE WAY

COAL PLANTS ARE USED

As power plants operators use coal

plants differently, the methods of

“The boiler eventually can’t take it anymore, and you’ll have uncontrollable slag formation.”- Joel Booher

1306pe_32 32 6/4/13 4:03 PM

Page 38: Power Engineering June 2013

www.power-eng.comFor info. http://powereng.hotims.com RS# 20

said. “Once slag becomes a problem,

their cleaning devices aren’t strong

enough or in the proper location to re-

move it.”

If buildup reaches a point the on-

line cleaning products installed by the

plant are unable to remove the slag,

the plant must be taken offline for

cleaning. Offline cleaning may involve

water jets, compressed air or dynamite.

USING DYNAMITE TO

CLEAN BOILER TUBES

Harty said that older methods be-

ing used for offline cleaning when

he first started cleaning boilers were

“very crude” and could involve using

shotguns to fire slugs at tubes to knock

off slag or using a large iron ball sus-

pended on a chain or chisels and ham-

mers to strike the tubes to remove any

build up.

“It was one massive thing to do, and

it was very dangerous,” he said. “They

had a lot of people get hurt.”

Modern methods of offline boiler

tube cleaning have made many im-

provements over older methods, and

Harty said using dynamite as a meth-

od of offline cleaning has multiple ad-

vantages over other methods, such as

high-pressure water, with one of those

being that no moisture is introduced

into the boiler.

“The water and moisture will go

down into the ash tanks and set like

concrete because that slag is in such a

fine state,” he said. “They buy that right

now to put in concrete and strengthen

the concrete. If you dry clean it with

explosives, you don’t have any mois-

ture and the slag will fall into the hop-

per and down into the grinder and out

the sluice area.”

Harty also said he can reduce down-

time for plants that have to be taken

offline for cleaning. Whereas using

high pressure water requires setting

up pipes and hoses, dynamite can be

down and back up can create some

efficiency for the plant by partially re-

moving the slag through cycling. Boil-

er tubes will expand up to 18 inches

from top to bottom when hot, and the

expansion and contraction of the tube-

can knock off slag.

Jeff Kite, principal engineer for boil-

er performance at Diamond Power,

said boilers in plants that are being

cycled more often don’t have to be

cleaned as often, but the boilers were

not designed to be cycled so it makes it

difficult on operations in general.

“Supercritical units do not easily

accommodate being asked to go from

full load to half load on a regular ba-

sis,” Booher added. “They’re designed

to be run at stable high loads, and it’s

hard on the metal throughout the boil-

er to be cycled up and down.”

CURRENT

CLEANING SYSTEMS

Most power plants have some sort of

soot blower system that works to clean

the plant when the boiler is online

and producing power, Martin said.

Soot blower systems have been around

since at least the 1930s, he said, adding

that he has seen photographs of soot

blowers that were operated by a chain

raised and lowered by a hand-operated

crank.

Soot blowers and other online

cleaning systems use compressed air,

steam or water to keep slag buildup

from occurring without the necessity

of taking the plant offline. As compa-

nies look for solutions that allow the

plant to keep operating, newer soot

blowing systems may allow a plant to

keep its boilers clean without requir-

ing a planned maintenance where the

boiler is taken offline, although older

systems may require a shutdown for

cleaning.

“Some of the online cleaning prod-

ucts might be 20 years old,” Martin

1306pe_33 33 6/4/13 4:03 PM

Page 39: Power Engineering June 2013

34

In order to clean a tube using explo-

sives, Harty said his company will use

primer cord around tubs that are close

together to avoid damage. The cord has

connectors that will delay the charges.

Without using the connectors, he said

the process could destroy the wall or

insulation of the boiler.

Sticks of dynamite can be used

used quickly and with less equipment.

He added that his company recently

cleaned a boiler in Nevada in less than

36 hours.

“Downtime is money,” he said.

“Downtime is loss of revenue. That’s

why they want you in and want you

out.”

Using dynamite to clean slag is

popular in western coal plants because

of the need to conserve water, he said.

“Water is really scarce out west, and

this is another reason explosives are

being used predominately in the west-

ern plants,” he said. “They can’t afford

to waste a drop of water, and by using

dynamite they’re able to save their wa-

ter and clean their boiler.”

Although soot cleaning systems may be used to

clean a boiler without taking it offline, a plant with

older online systems may require a shutdown.

Photo courtesy of Norm Harty.

1306pe_34 34 6/4/13 4:03 PM

Page 40: Power Engineering June 2013

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Page 41: Power Engineering June 2013

www.power-eng.com36

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after hitting the hot boiler tube, could

create more steam than the boiler

could handle and even cause a change

in the power produced by the boiler.

“Many units have induced draft fans

that really run on the ragged edge, and

they can’t handle that extra gas volume

going through there,” Booher said.

“Oftentimes these high-flow cleaning

devices can cause disturbances of the

unit.”

Modern systems can use retractable

soot blowers, such as Diamond’s Pow-

er HydroJet™ water cleaning systems,

allowing less water to be used since

less force can be used over the shorter

distance. Systems using retractable

soot blowers can create a 60 or 70 per-

cent water use reduction and provide

as much or better cleaning effective-

ness, Kite said.

The systems can also interpret where

the boiler is developing a buildup of

slag, which can help operators avoid

attempting to clean sections of tube

that are already clean. If water or steam

hits a clean section of a boiler tube, it

can cause tube erosion over time. Cold

water hitting a hot tube can also cause

the tube to contract, leading to tube

damage and a possible blow out.

“Water cleaning can damage tubes if

done improperly,” Kite said. “If an op-

erator has this wonderful tool that can

clean his boiler, he has a habit of us-

ing it too much if he doesn’t have input

coming back to him letting him know

what’s going on.”

make a sequence and run the devices

in order, operators were unable to get

any sort of feedback without a visual

inspection of the boiler.

“Realistically, it wasn’t until the ‘90s

that we started implementing heat

transfer sensors, which are devices

made out of sections of boiler tubing

placed within the cleaning radius of

the water lances that provide feedback

of heat transfer and can be used to de-

termine how clean or dirty that section

is,” Kite said.

Older soot blower systems might

also utilize an “across-the-boiler” sys-

tem, where a nozzle will need to spray

water across a 60-foot space in order

to reach the place that needed to be

cleaned. That system might use 200

gallons of water per minute, which,

in more open places where there is a

heavy amount of slag. Harty said he

has seen slag reach 60 to 70 feet deep

in some boilers. At one point, his com-

pany cleaned 150 truckloads of slag

from a boiler, though he called that

“an extreme case.”

IMPROVEMENTS

IN ONLINE BOILER

CLEANING

Many companies would prefer to not

take their plants offline for cleaning,

and both Diamond Power and Clyde

Bergemann have developed online

cleaning solutions that are improve-

ments over the previous soot blowers.

Previous soot blowers had “sim-

plistic controls,” Kite said. Although

the operator of the system was able to

Modern systems use a variety of solutions to create “intelligent soot blowing,” which can help prevent outages and damage to the boiler.- Jeff Kite, Diamond Power

1306pe_36 36 6/4/13 4:03 PM

Page 42: Power Engineering June 2013

www.power-eng.com 37

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devices installed in the system and

that device’s ability to impact the goals

set by the plant operator. Ultimately,

the system will allow an operator to

clean tubes only when and where they

need cleaning.

“The idea would be to use it as

little as possible because it can cause

damage to the unit,” Booher said.

“If the system can automatically

determine where to clean and which

blowers make the biggest effect, then

in the end you can end up blowing

less soot blowers to maintain the same

general boiler cleanliness.”

VARIABLE PRESSURE

BLOWERS

Clyde Bergemann has also intro-

duced a variation in intelligent soot

be difficult for the operations staff to

understand in order to make the right

decisions,” he said. “Goal-based ISB

uses intelligent soot blowing to achieve

the goals the operators already want to

achieve – keeping steam temperature

in the right range or keeping their gas

temperatures in the right range. It’s

simpler and quicker to commission.”

Although gas temperature may

be a common goal for many boiler

operators, Booher said different

operators may have a different goal

that is important to them. Diamond

Power will work with the plant

engineering staff to configure the ISB

system, and if a goal can be quantified,

it can be incorporated into the system.

Once the system is in place, it will

analyze data from individual cleaning

Modern systems use a variety of

solutions to provide “intelligent soot

blowing,” which can help prevent out-

ages and damage to the boiler.

GOAL-BASED INTELLIGENT

SOOT BLOWING

Intelligent soot blowing, or ISB, uses

automatic control systems to analyze

the cleaning needs of the boiler.

Introduced in the ‘90s, it is becoming

the standard for boilers, Booher

said, with many new boilers using

an ISB system. Improvements can

still be made on previous generation

of intelligent soot blowing systems,

however.

“What is coming to light is that

these systems can be complicated in

their calculations, and so they can

1306pe_37 37 6/4/13 4:03 PM

Page 43: Power Engineering June 2013

www.power-eng.com38

to remove one pound of iron oxide. The

same amount of iron oxide can be re-

moved by 2.5 pounds of citric acid or

1.58 pounds of hydrochloric acid.

“When you look at costs, I can clean

a 30,000 gallon boiler for around

$50,000 to $60,000,” he said. “Clean-

ing that same boiler with EDTA will

cost you over $100,000.”

Bodman said his company will run

solubility tests with hydrocholic acid,

citric acid and EDTA and allow the

company to choose the method used.

Once the cleaning starts, he said it

takes approximately 2 to 3.5 days. De-

pending on the boiler and water treat-

ment, some boilers require cleaning

every two years, while other boilers,

like ones used in paper mills, may be

cleaned every five to seven years.

A VARIETY OF OPTIONS

Although boiler tube cleaning is a

very important part of the industry,

choosing the right method for a boiler

is up to the operator. Modern advances

in the industry, however, can make the

process simpler and safer than it used

to be, however.

“Soot blowing has really changed

over the years, going from a product

that you just install and turn on into

really getting more into the engineering

aspect and studying how it affects the

boiler performance,” Martin said.

Whether an operator chooses to

install a new online system or use

an offline system, each boiler may

have different problems and require

a unique solution to reach maximum

efficiency. For Harty, who went from

blasting passes for roadways to using

dynamite to clean multi-million dollar

pieces equipment almost 50 years

ago and has seen cleaning systems

continue to evolve during that time,

finding solutions to unique problems

is a familiar concept.

“In a power plant, you have to be

flexible and innovative,” he said.

INTERIOR TUBE CLEANING

Although cleaning slag from the in-

side of the boiler and exterior of the

boiler tubes is a key aspect of keeping

a boiler efficient, cleaning any depos-

its that may form on the interior of the

tubes is also important.

If deposits from impurities in the

water form on the interior of a tube, it

can create an insulation problem, ac-

cording to George Bodman of George

H. Bodman Inc.

“if you put a tenth of an inch of scale

in there, your temperature will go from

600 degrees farenheit to probably 700

to 750 degrees farenheit,” he said. “If

that tube gets to 809 degrees farenheit,

the tube is going to blow out.”

Scaling can also reduce the efficien-

cy of the boiler by requiring more heat,

and corrosion can form under the scale

that will create a hole in the tube itself.

The process of removing the scale is

individualized for each tube, Bodman

said, and the preplanning for the clean-

ing should start at least six months in

advance by getting a tube sample of

the boiler. The sample can be used to

determine the deposit weight density

as well as the scale matrix.

Bodman said he also talks to the

water treatment representatives to find

out what has previously been done and

why the deposit has formed. The next

step after that is to speak with plant

personnel and the plant chemist or rel-

ibility engineer to set up a program on

how to remove the deposit.

Around 90 percent of boilers are are

currently chemically cleaned, Bodman

said, although some can be cleaned

with high-pressure water.

Plant operators can choose to use a

variety of chemicals, including hydro-

chloric acid, ethalene diamene tetra-

cedic acid (EDTA) and hydroxyacetic-

formic acid.

EDTA is more expensive, but also has

less environmental impact, Bodman

said. It requires 13.6 pounds of EDTA

blowing that uses variable pressure

when cleaning boiler tubes. Martin

said the goal of the system is to provide

just enough pressure to clean the tube

to avoid creating any damage.

“We could go in with a very, very

high pressure, and we know that

whatever is on the tube is going to

be cleaned, but there’s a downside to

that, and that’s tube erosion,” he said.

“What the SMART Clean™ does is look

at cleaning with the proper intensity.

We clean with just enough intensity to

clean the ash off the tube, but not too

much intensity to cause tube erosion.”

The system is designed to create

maximum efficiency for the plant.

By keeping slag from building up on

the tubes, the plant is able to operate

with maximum heat transfer, and by

avoiding erosion, the operator can

prevent future tube leaks that can shut

down the boiler in a forced outage.

Martin said the system can save

money for a plant operator by

completely eliminating planned

outages to clean the tubes. He said

the company has clients with boilers

that were going offline every three

months who eliminated the problem

by installing the SMART Clean™

system. Those boilers only come down

for typical maintenance issues now, he

said.

He added the system is not a large

investment for a boiler operator, and

the investment will be returned within

six months to a year, with the owner of

the boiler receiving the benefits of not

requiring outages for the next 20 years.

Each job requires a different

approach, and not all of the SMART

Clean™ products may not be necessary.

“We use a lot of different techniques,”

Martin said. “Some are more advanced

than others. Really, every boiler is

unique. We look at it from a fresh

perspective and look at their specific

needs, and then we can propose the

right technology to meet those needs.”

1306pe_38 38 6/4/13 4:03 PM

Page 44: Power Engineering June 2013

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1306pe_39 39 6/4/13 4:03 PM

Page 45: Power Engineering June 2013

www.power-eng.com40

Gas Turbine Startup Diagram 1

Spee

d, L

oad

(%)

120

100

80

60

40

20

0

Minutes

0 10 20 30 40 50 60

0 – Start Command1 – LCI engages2 – HRSG Purge Start 4 – Ignition Speed5 – GT Fire + Warmup6 – Full Speed No Load (FSNL)7 – Synchronization8 – Full Speed Full Load (FSFL)

Start Command to FSFL: 40 minutes

18 minutes (Fast Start)

Conventional

Fast

Speed

Load

Purg

e C

redi

t + L

CI P

reco

nnec

t + “

Fire

on

the

Fly”

Fast

Loa

ding

(2

0+

% p

er m

inut

e)

Nor

mal

Loa

ding

(~

8% p

er m

inut

e)

Nor

mal

Loa

ding

(~

8% p

er m

inut

e)

GT Load Hold for ST Temp. Matching(Conventional Start)

Typical gas turbine startup diagram (conventional and fast versions). Conventional start with GT hold can take up to 50 minutes to reach MECL. Purge credit shaves off 12 minutes of that time. Eliminating GT hold saves another 15+ minutes. With fast start feature MECL point is passed in less than 10 minutes.

C

6

2

5

54

7

7

3

0 0

1

1

8

8

8 86

F

Alas, modern gas turbine based com-

bined cycle (GTCC) systems comprise

steel behemoths weighing tens of

thousands of pounds and operate at

extremely high pressures and tempera-

tures while connected to each other via

a maze of pipes and valves.  This com-

plex architecture presents formidable

challenges to designers and operators

alike to handle major operational

transients with large flow, pressure

and temperature (FPT) gradients with-

out adverse impact on reliability, avail-

ability and maintainability (RAM).

This is primarily achieved by advanced

control schemes incorporating model

based controls (MBC), design features

such as terminal attemperators and

cascaded steam bypass as well as mate-

rial selection. As a result, in terms of

dynamic response to transient events,

the difference between a modern

GTCC and its forerunners is as pro-

nounced as that between cars with car-

bureted vis-à-vis fuel-injected engines.

The goal of this article is to provide

the reader with relevant and easy-to-

use technical information (in the form

Nowadays all major

gas turbine OEMs

promote their

products with an

emphasis on “flex-

ibility” in addition to output and effi-

ciency.  The most advertised flexibility

feature is the fast start capability of

advanced F, G or H class machines in

simple and combined cycle modes. 

Gas Turbine Combined Cycle Fast Start:

The PHYSICSBehind the Concept BY S. C. GÜLEN, BECHTEL, PRINCIPAL ENGINEER

1306pe_40 40 6/4/13 4:03 PM

Page 46: Power Engineering June 2013

www.power-eng.com 41

Steam Turbine Cool-Down Profles 2

ST M

etal

Tem

pera

ture

(˚F

)

1,200

1,000

800

600

400

200

0

Time Since Shutdown, hours

0 50 100 150 200

HOT WARM COLDHOT WARM COLD

HP Inner Bowl

IP Inner Bowl

�c = 100-150 hrs. (HP)

�c = 50-75 hrs. (IP)

Typical steam turbine cool-down profles (as measured at HP and IP inner bowls). Shaded regions indicate typical time windows for “hot”, “warm” and “cold” start classifcations. Red dashed lines indicate average metal HP bowl temperature corresponding to the same.

�C

or load up-down ramps) and associ-

ated thermal stress-strain loop.

In principle, the solution is simple

enough: thermal decoupling of GT and

ST start processes. Thus, GT is started

and rolled to full speed at no load

(FSNL) at the maximum rate dictated

by the size of static starter (Load Com-

mutating Inverter, LCI), shaft torque

limit, particular Dry Low NOx (DLN)

combustion system limits (e.g., avail-

ability of heated fuel gas, minimum

fuel requirement by the lean blow-out

margin, Wobbe index variation, etc.)

among others. Following synchroni-

zation, GT is loaded as fast as possible

first to its minimum emissions-com-

pliant load (MECL) and then to its full

load at full speed (FSFL).

GTCC start time definition hinges

on when to start the chronometer. Un-

less specified unambiguously, one can

never be sure when time t = 0 is and

the difference can be significant. For

a conventional start with HRSG purge

and normal loading rate (i.e., no holds

anything” in the process - literally. The

failure mode to avoid is crack initia-

tion and propagation. Failure to con-

trol thermal stresses results in cracks

via low/high cycle fatigue (LCF and

HCF) and brittle fracture. In fact, LCF

is found to account for roughly two

thirds of ST rotor life with the remain-

der attributable mainly to creep. In

particular, thick-walled components

such as HP drum, ST valves, casings

and rotor are exposed to LCF due to

thermal cycling (start-stop sequence

of simple charts, basic equations and

representative physical quantities) to

form an informed opinion on avail-

able technologies and their purported

capabilities and benefits along with

potential pitfalls and physical limits.

The focus is on GTCC startup, which

can be considered as a primus inter pares

among all GTCC transients. Admitted-

ly, an article limited to a few thousand

words cannot do justice to the subject

matter at hand. The reader is encour-

aged to consult the listed references for

a thorough understanding and guid-

ance for applying the basic principles

to his/her own projects.

There are many considerations in a

successful GTCC start from standstill,

which are discussed in detail else-

where [1-3]. Correct steam chemistry,

establishment of steam seals, vibra-

tion, overspeed and thrust controls are

all vital for acceptable component life

and RAM. When all said and done,

however, the single most important

issue from a fast start perspective is

steam turbine (ST) thermal stress

management. Furthermore, if the heat

recovery steam generator (HRSG) is

drum-type, high pressure (HP) drum

thermal stress management becomes

an integral part of the problem.

In a nutshell, GTCC startup optimi-

zation problem can be formulated as

to minimize the time required to reach

the dispatch power (e.g., full load or a

specific part load) without “breaking

Modulus of Elasticity E 26,000 ksi

Linear Coefficientof Thermal Expansion

α 6-7 x 10-6 1/R

Poisson's Ratio ν 0.30

Thermal Conductivity k 18.0 Btu/h-ft-F

Density ρ 490 lb/cuft

Heat Capacity c 0.125-0.175 Btu/lb-R

Thermal Diffusivity δ 0.20-0.25 ft2/h

Defnition of key material parameters and their typical values 1

Source:

1306pe_41 41 6/4/13 4:03 PM

Page 47: Power Engineering June 2013

www.power-eng.com42

S-N and CLE Curves 3

Typical S-N and CLE curves for ST rotor LCF (CrMoV) [5]. Metal �T in CLE chart represents the total temperature change between initial and fnal states (beyond 600°F, curves are fat).

Tota

l Str

ain

Ra

ng

e

1.000

0.100

0.010

0.001

10 100 1,000 10,000 100,000

S-N Curve CLE Curve

Cycles to Failure

0 100 200 300 400 500 600

10.0

8.3

6.7

5.0

3.3

1.7

0.0

σ�max = 44,54, 87 ksi

for K� = 2.0, 1.5 and 1.0

σ�max = 44,54, 87 ksi

for K� = 2.0, 1.5 and 1.0

5,000 Cycles5,000 Cycles

Increasing��, �

Increasing��, �

ΔT/

Δt,

˚F/m

in.

Metal Temp. �, ˚F

0.100

0.050

0.0200.010

0.001

0.100

0.050

0.0200.010

0.001

1

5,000 = 0.02%

1

5,000 = 0.02%

Steam Turbine Roll Times 4

Steam turbine roll times for varying steam fows and temperatures. (Steam pressure 120 psia,rotational inertia 700 kp-ft2, rated IP turbine inlet fow 681.5 kpph.)

Steam T = 700˚F

800˚ F

900˚F

Stem Flow, % of Rated

ST

Ro

ll Ti

me, m

inu

tes

18

16

14

12

10

8

6

4

2

0

0% 5% 10% 15% 20% 25% 30%

Steam T = 700˚F

800˚ F

900˚ F

low load with reduced exhaust en-

ergy (flow and temperature) to con-

trol HRSG steam production rate and

steam temperatures (at the HP drum

and HP superheater exit). Elimination

of direct HRSG steam temperature

control via GT load and exhaust ener-

gy is the “thermal decoupling”, which

is the key enabler of fast start. It can be

the rule is sequential combustion (reheat)

GTs, which can turn off their second

combustors to operate at 20% or lower

load while emissions-compliant.

Two steps are instrumental in reduc-

ing GT start time: elimination of (i)

HRSG purge sequence (by performing

it right after shutdown in compliance

with NFPA® 85) and (ii) hold time at

for HRSG warming) the difference be-

tween start command and ignition is

20 minutes (see Figure 1). Thus, the

same start time (40 minutes to be ex-

act) can be quoted as 20 minutes by

someone who sets t = 0 at ignition.

Today’s fast start GTs with features like

“purge credit”, LCI pre-connect and

“fire on the fly” can reach FSFL in 18

minutes or less from the start com-

mand (depending on the loading rate).

The rush to MECL is critical for re-

duction of startup emissions. The

reason for that lies in the basic design

philosophy of modern DLN combus-

tors with fuel-air premixing, which are

designed to run near the lean limit for

low emissions. This is accomplished

by piloted, multi-nozzle fuel injectors

via sequential activation of fuel flow

through individual nozzles (known as

staging) to prevent lean blow-out and

combustion dynamics while staying

within the narrow equivalence ratio

band to control NOx and CO emis-

sions. For older units MECL is 60%;

for modern units the low load limit

is around 50% (maybe 40% for most

advanced systems). The exception to

1306pe_42 42 6/5/13 10:38 AM

Page 48: Power Engineering June 2013

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1306pe_43 43 6/4/13 4:03 PM

Page 49: Power Engineering June 2013

www.power-eng.com44

Steam Turbine Roll 5

center

Tem

pera

tur,

˚F

1,000

800

700

200

100

Time, minutes

70 80 90 120

100

80

70

60

40

20

10

Spee

d, F

low

& S

tress

, %

Typical ST roll via IP steam admission and the ensuing warm-up period [6]. Representative of a single-shaft GTCC cold start (total three hours). Note how the quasi-stationary Phase II is preceded by a short non-stationary period.

Rotor

Temperature

Phase I Phase II

Non-stationary start to Phase II

Steam Temperature

� = 30 min.

� =

78

min

.

� = 235 min.

Steam Flow

Max

. �

Bulk

Surfa

ce

ST S

peed

T

r

Surface Stress

steamsurface

mean

to start maintenance as soon as pos-

sible to minimize the downtime). The

natural cooling time depicted in Figure

2 is represented by the exponential de-

cay law

Eq. 1

with a characteristic cooling time con-

stant, τc, as a function of the ambient

temperature, Tamb

, and the starting

value (denoted by subscript 0). This

temperature is the main GTCC startup

classification gauge instead of widely

used but fuzzy terms such as “hot” or

“warm”, whose definitions vary from

one source to another.

Component Tm

and, more precisely,

its variation in a metal structure across

a characteristic dimension, Lc, (e.g., di-

ameter of ST rotor – 20-25 in. for mod-

ern GTCC units) along a characteristic

dimension, x, is the key determinant

of thermal stress via the following for-

mula:

Eq. 2

where E’ = E / (1-ν). For the ST rotor,

ΔTm

in Eq. 2 is the difference between

rotor surface or bore and mean body

(bulk) temperatures for surface and

bore stresses, respectively. For a given

steam temperature, Tstm

, bulk rotor

body Tm

varies according to the expo-

nential decay law

accomplished via a bypass stack and

modulated damper controlling the

exhaust flow to the HRSG. A recently

proposed technique is “air attempera-

tion” of the GT exhaust gas flow via

air injection into the transition duct.

Ignoring the obvious but wasteful

practice of “sky venting”, the currently

accepted method is a “cascaded” steam

bypass system with terminal attem-

perators (TA). Steam generation and

temperature-pressure ramp rates in HP

drum are dictated by GT exhaust en-

ergy whereas final steam temperature

control is accomplished by TAs. Until

steam temperatures reach acceptable

levels for admission into the ST, steam

is bypassed via a route including the

reheat superheater so that the latter is

pressurized and “wet” (i.e., cooled by

steam flow obviating the need for ex-

pensive alloys).

Steam FPT acceptable for admission

into the ST is dictated by metal tem-

peratures (primarily valves, casings or

shells and the rotor). The critical com-

ponent is the rotor, whose temperature

cannot be measured directly and in-

ferred by proxies (e.g., HP and IP inner

bowl). ST metal temperature, Tm

, is a

direct function of unit downtime and

ambient temperature as shown in Fig-

ure 2 (unless forced cooling is applied

Source:

m/mo

P T h Bi δ τ

[-] psia F Btu/h-ft2-F [-] ft2/h min

1.0 120 700 116 7 0.26 37

1.0 120 1,050 100 6 0.21 54

1.0 1,200 700 958 56 5

1.0 1,200 1,050 701 41 8

0.2 120 700 32 2 135

0.2 120 1,050 28 2 196

0.2 1,200 700 264 15 16

0.2 1,200 1,050 193 11 28

Representative values of major parameters characterizing the transient heat transfer during steam turbine warm-up for typical steam fow, pressure and temperatures.

2

1306pe_44 44 6/4/13 4:03 PM

Page 50: Power Engineering June 2013

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1306pe_45 45 6/4/13 4:03 PM

Page 51: Power Engineering June 2013

www.power-eng.com46

Determination of HTC is one of the

most uncertainty-prone undertakings

in transient heat transfer problem in a

complex geometry such as steam path

flow. Its dependence on steam flow is

based on the well-known Nusselt num-

ber correlation for heat transfer in in-

ternal flows, i.e., h ∝ . The heat

transferred from steam to the rotor at

the surface increases the rotor’s bulk

temperature according to Fourier’s law

Eq. 6

Equation 6 introduces the thermal

diffusivity, δ = k/ρc, which quantifies

the speed with which the temperature

of a heated or cooled body changes.

Typical values for the key parameters

governing ST rotor thermal transients

are given in Table 2.

For ferritic steels used in modern

GTCC units, k and ρ do not show sig-

nificant variation. Thus, δ is primarily

a function of temperature and chang-

es by about 25% between 700 and

1,050°F; i.e., rate of change of metal

temperature is 25% faster at the higher

temperature. The data in Table 2 can

be summarized as follows: higher

steam flow and/or pressure result in

higher rates of heat transfer between

steam and metal, which is quantified

by higher Biot numbers and shorter

time constants (i.e., faster heating

or cooling). In conjunction with the

data in Table 2, Eqs. 5 and 6 identify

the two distinct phases in ST start with

thermal stress control:

(i) low flow and high steam-metal

ΔT with low HTC until tempera-

ture gradients settle down (non-

stationary phase or Phase I) and

(ii) increasing steam FPT to load the

unit with high HTC and nearly

constant, low steam-metal ΔT

(quasi-stationary phase or Phase II).

Equation 5 describes Phase I via its

simplified solution for a cylindrical ge-

ometry given by [4]

Eq. 7

which gives the maximum thermal

stress implied by a given step rise in

Tstm

at time t = 0 (with a time lag char-

acterized by the Biot number). Note

that the base stress formula of Eq. 2 is

amplified by a stress concentration factor

KT, which accounts for the presence of

geometric discontinuities on the rotor

Eq. 3

with a characteristic time constant, τ,

which is a function of rotor material

(e.g., 1% CrMoV) and size cum geom-

etry represented by Lc,

Eq. 4

where h is the convective heat trans-

fer coefficient (HTC) between steam

and metal. Equations 1-4 tell the en-

tire ST thermal stress management

story in the concise language of math-

ematics. Thermal stress is determined

by the temperature gradient in the ro-

tor (essentially a cylinder) via Eq. 2;

the latter is determined by the initial

steam-metal ΔT (denominator of LHS

of Eq. 3) with a time lag, which itself is

dictated by HTC in Eq. 4. Everything

hinges on the initial value of Tm

, Tm,0

,

which is a function of the cooling pe-

riod (Eq. 1).

In physical terms, this translates

into a mechanism to control steam FPT

into the steam turbine at initial values

sufficient (i) to roll the unit from turn-

ing gear (TG) speed to FSNL, (ii) to

warm the ST rotor until steam-metal

ΔT decreases to an acceptable level

and (iii) to ramp them up at acceptable

rates to their rated levels while ensur-

ing that thermal stresses do not exceed

prescribed limits.

Steam flow enters the picture via

HTC in Eq. 4, which controls the rate

of heat transfer between steam and the

rotor surface as described by the heat

flux balance at the steam-metal bound-

ary (x = 0)

Eq. 5

This equation introduces the di-

mensionless Biot number, Bi = h·Lc/k,

which is a relative measure of the

uniformity of temperature gradi-

ents inside a heated or cooled body.

Dynamic Response of Selected HRSG

Heat Exchanger Sections6

Representative of a single-shaft GTCC cold start (total time of about three hours).

TEM

PERA

TURE

TIME

Warm-Up Hold

HP Sphtr.

GT

Exha

ust

HP Drum IP/LP Sphtrs.

IP Drum

LP Drum

Increasing �

2 min.

7.5 min.

12.5 min.15 min.

20 min.10-1

5 ˚F

/min

.

(< ~

50

psi/m

in.)

1306pe_46 46 6/4/13 4:03 PM

Page 52: Power Engineering June 2013

www.power-eng.com

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(which is not a perfect cylinder after all). Similarly, Eq. 6

describes Phase II via its simplified form given by

Eq. 8

where ϕF is the form factor (0.125 for a cylinder [4]). Equa-

tion 8 gives the allowable Tstm

ramp rate for a given maxi-

mum allowable stress, σmax

, which is dependent on rotor ma-

terial and typically lies in a range of 50-80 ksi. For the cited

range, with the data in Table 2, Eq. 7 suggests that for low

HTC (~100 Btu/h-ft2-F or less) steam-metal ΔT can range

from 200-300°F (high KT) to 500°F and higher (low K

T).

For high HTC (~650 Btu/h-ft2-F), steam-metal ΔT can range

from 100-200°F (high KT) to about 400°F (low K

T). Simi-

larly, using Eq. 8 with Table 2, it can be seen that allowable

values for dTstm

/dt range from 3-6°F to 8-10°F.

The allowable stress is not a precisely defined material

property. (For ferritic steels used in ST rotor construction,

0.2% tensile yield strength lies between 70-90 ksi for tem-

peratures 600-1,000°F.) It is derived from the S-N curves re-

lating total strain to cycles to failure, which gives the fatigue

life of the material in question (for LCF life of CrMoV alloy

see Figure 3). Based on the relationship between stress and

strain, ε, via the modulus of elasticity, σ = E´ • ε, this curve is

used to determine σmax

for a defined fatigue life. In practice,

the relationship between σ and ΔT allows the translation

of the S-N curve into Cyclic Life Ependiture (CLE) curves,

which determine the allowable Tstm

ramp rates (Figure 3).

Depending on the rotor material, size and geometry and its

temperature at start initiation, the range is limited to about

5 to 10°F per minute except for very hot “restarts” after a

few hours of downtime.

Steam turbines with cascaded steam bypass are typically

started by admitting steam from the reheat superheater into

the IP section. Admission steam FPT should be sufficient

to overcome the rotational inertia (in lb-ft2) of the entire

ST and its generator, Irot

, and accelerate it from TG speed (a

few rpm) to FSNL (3,000 or 3,600 rpm). Based on avail-

able steam FPT and initial IP rotor temperature, using the

relationship between ST power generation (expansion from

IP inlet to the condenser), rotor torque and rate of change

in angular speed, ω, the roll time can be estimated as 2 to

15 minutes (see Figure 4) via

Eq. 9

where N is the rotor speed (rpm) and the argument of

the integral on the RHS of Eq. 9 is the power (in Btu/s) gen-

erated by steam expanding between IP turbine inlet and

condenser [6].

1306pe_47 47 6/4/13 4:03 PM

Page 53: Power Engineering June 2013

www.power-eng.com48

Startup Time 7

ST Only

Startup time of a typical steam turbine in a modern GTCC with drum-type HRSG (from the start of ST roll to the point when all bypass valves are closed and all admission valves are fully open).

Star

t Tim

e, m

inut

es

250

200

150

100

50

0

Initial ST Metal Temperature, ˚F

0 200 400 600 800 1,000

Downtime, hours

� 166 97 58 27 5

rpm

/min

, ˚F/

min

16

14

12

10

8

6

4

2

0

Steam Temperature Ramp Rate

Shaft Acceleration Rate

GT Hold For HRSG

Warm

up

The chart in Figure 5 shows the

first two hours of ST roll, warm-up

and loading phases for an initial Tm

of

180°F (about 5-6 days of downtime per

Figure 2). Steam is admitted into the IP

turbine at 715°F and 120 psia at a flow

rate of 10% of its rated value at full

load. This is sufficient for acceleration

from TG to synchronization in 8 min-

utes (see Figure 4). Initial steam-metal

ΔT is 500+°F but this is acceptable due

to the low HTC (less than 30 Btu/h-

ft2-F per Table 2) and the ensuing low

σmax

from Eq. 7 (also very high τ > 200

minutes). Following synchronization,

IP steam flow is ramped steadily to

40% to accelerate the warm-up process

via increased HTC. Once the steam-

metal ΔT (based on rotor surface tem-

perature inferred via IP inner bowl

thermocouple) reaches about 250°F,

Tstm

is ramped (via TA control) at a rate

defined by the CLE curve (about 3 to

4°F per minute for an acceptable life of

4 to 5,000 cycles from Figure 3).

The other component subject to LCF

damage due to cycling is the cylindri-

cal HP drum of the HRSG (4-5 inches

wall thickness). The limiting thermal

stress is at the inner drum wall con-

trolled by saturated steam p-T inside

the drum. During startup, mechani-

cal stress due to internal drum pres-

sure and thermal stress due to thermal

expansion are in opposite directions,

while they are in the same direction

during shutdown. Unlike the ST,

which is thermally decoupled from the

GT via TAs, HRSG sections are directly

“under fire”. They respond to GT ex-

haust temperature transients much

faster than the ST rotor in direct pro-

portion to their distance from the inlet

(see Figure 6). Thermal stress calcula-

tions and material properties similar

to those described above limit the p-T

ramp rate inside the drum to 10-15 °F/

min (about 50 psi/min max.) for units

designed up to ~1,800 psig at ST throt-

tle (~6-10% higher at the HP drum).

Advanced steam cycles with 2,400

psig throttle and drum-type HRSGs

(very thick walls) would push down

the ramp rate to a few degrees per

minute (see Eq. 8 for the relationship

between dTstm

/dt and Lc). This can be

alleviated to a certain degree by using

stronger alloy steel (obviously more

expensive) and/or designing the HRSG

per EN-12952 rather than the ASME

code, which results in thinner walls.

One obvious solution is once-through

design of the HP evaporator, which

eliminates the thick-walled drum al-

together but has its own drawbacks

and caveats. A recent design approach

proposes to replace the HP drum by a

cylindrical, thin-walled knock-out ves-

sel with external separator bottles and

thus avoid the thermal stress problem

in cold starts. According to HRSG

OEMs, cold starts (Tdrum

< ~400°F) are

20 times more damaging than warm

starts (Tdrum

< ~500°F) whereas hot

starts (Tdrum

> 500°F) do not impact

LCF life. In “hot” starts, HP and reheat

superheaters subjected to very steep

gas temperature ramps are critical in

terms of HRSG life consumption. In

this context, one should add that the

desirability of purge credit is due to

more than startup time reduction. It

prevents excessive quenching of super-

heaters, which act as “supercoolers”

during hot starts when subjected to

relatively cold GT exhaust with detri-

mental impact on their fatigue life.

Natural p-T decay of the HP drum

can be described by Eq. 1 with τc of 60

to 80 hours. It takes about 2-3 days

for the pressure to decay to the atmo-

spheric conditions. Bottling up the

HRSG via stack dampers with insula-

tion up to the damper, steam sparging

(requires auxiliary boiler) or running

the SCR ammonia vaporizer heaters

help keep the HRSG warm and pressur-

ized over limited duration shutdowns

1306pe_48 48 6/4/13 4:03 PM

Page 54: Power Engineering June 2013

www.power-eng.com 49

THE WORLD’S FIRST IMPACT & TORQUE GUN

PUSH the shifter handle forward, engage the 4,000 rpm

high speed impact at low noise and vibration for a quick,

corrosion-overcoming pre-torque or run-up.

PULL the shifter handle back, engage the continuous

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OD

UCT OF THE YEAR

the

company

torque guntm

TM

TM

to enable GT starts with no low-load

hold. Beyond about three days, how-

ever, this is increasingly impractical

and even in plants designed for fast

starts limited duration GT holds are

needed to accomplish HP drum warm-

up in two steps (somewhat similar to

that shown in Figure 6).

Combining the elements discussed

above and illustrated by the ST roll

example in Figure 5, a representative

ST start curve can be established as a

function of the key controlling param-

eter, namely, ST metal temperature at

the startup initiation (Figure 7). Ap-

propriate GT start time per Figure 1

(from start command to the point

when ST roll begins) should be added

to that for total GTCC start time (e.g.,

18 minutes for the fast start). The four-

minute mile of fast start capability is

roughly 30 minutes from a standstill

(to be defined precisely) to combined

cycle full load for a "hot" start (e.g., fol-

lowing an overnight shutdown).  This

is generally compared to a conven-

tional hot start, which takes around

one hour (see Figure 1). The under-

lying physics discussed herein briefly

and summarized in Figure 7 hopefully

makes it clear that this particular case

is only one single point in a continuum

of start scenarios driven mainly by the

downtime preceding the pushing of

the start button.

References

1. Chrusciel, A., Zachary, J., Keith, S., 2001,

“Challenges in the Design of High Load

Cycling Operation for Combined Cycle

Power Plants,” POWER-GEN International

2001, Las Vegas, NV.

2. Akhtar, Z., 2006,”Design Features for

Minimizing Start-Up Time in Combined

Cycle Plants,” POWER-GEN Europe 2006,

Köln, Germany.

3. Ugolini, D.J., Bauerschmidt, J.R., 2006,

“Optimization of Start-Up Times for Com-

bined Cycle Power Plants,” Electric Power

Conference 2006, Atlanta, GA.

4. VGB PowerTech Guideline, 1990, “Ther-

mal Behaviour of Steam Turbines, Re-

vised 2nd Ed.,” VGB-R105e, VGB Pow-

erTech Service GmbH, Essen, Germany.

5. Viswanathan, R., 1989, “Damage Mecha-

nisms and Life Assessment of High-Tem-

perature Components,” ASM Internation-

al, Metals Park, OH, USA.

6. Gülen, S.C., Kim, K., 2013, “Gas Turbine

Combined Cycle Dynamic Simulation:

A Physics Based Simple Approach,”

GT2013-94584, ASME Turbo Expo, June

3-7, 2013, San Antonio, TX, USA.

1306pe_49 49 6/4/13 4:03 PM

Page 55: Power Engineering June 2013

www.power-eng.com50

Source: www.aircleancompany.com

#ESP Process Schematic

Dirty Air Clean Air

Ground Plate

Ground Plate

ParticleParticle Charged

Particle

Charged

Particle Sp

aci

ng

Sp

aci

ng

Sp

aci

ng

Sp

aci

ng

IonizerIonizer High voltage PlateHigh voltage Plate

Zoneof

Charging

Zoneof

Charging

Upgrading Electrostatic PrecipitatorsBY BRYANT PURSE, RAYMOND ZBACNIK, MITCHELL KRASNOPOLER, KIEWIT POWER ENGINEERS

ESPs. This article will address some of

the general principles of dry electro-

static precipitators and discuss modern

methods for upgrading ESPs.

BASICS OF ELECTROSTATIC

PRECIPITATORS

ESPs can be designed for high volu-

metric gas flow rates, variable tem-

peratures and pressures, and variable

particulate loading. Precipitators have

been placed in a number of locations

at different power plants, including

downstream of the economizer (hot

side), downstream of the air preheat-

er (cold side), or after a wet scrubber

(which requires a wet ESP). This article

will focus on dry ESPs and will high-

light typical upgrade options. With a

properly designed electrostatic precipi-

tator, 99% collection efficiency is pos-

sible with medium and high ash coals.

History and Principles of ESPs

The first electrostatic precipitator

was developed by a physical chemis-

try professor, Dr. Frederick Cottrell, in

1906. He was awarded a patent for his

design on August 11, 1908. Dr. Cot-

trell successfully demonstrated in his

research the precipitation of particu-

lates from an air stream via particle

charging in an electric field. The prin-

ciples in this early design still apply

today. Transformer-rectifiers energize

discharge electrodes with a negative

potential, producing an electrical field

between the discharge electrodes and

the positively-grounded collecting

plates.

Particulate matter that enters the

electrical field develops a negative

charge and migrates away from the

discharge electrodes and towards the

collecting plates. When the particu-

lates reach the collection plates, the

negative charge is neutralized and a

cake-like layer of ash accumulates. Mi-

gration and collection of the charged

particles depends upon the particu-

late resistivity and the electrical field

between the two electrodes, as well

as the gas flow profile. Particulate

matter that precipitates on the collec-

tion plates is periodically removed by

Electrostatic precipitators

(ESPs) have been used for

over 100 years to remove

entrained solid particu-

lates or fine mists from

gas flows in the power, cement, metal

production, paper, and other indus-

tries. As a response to ever changing

state and federal regulations for coal-

fired utility power plants, existing

ESPs or new air quality control sys-

tems are needed to meet lower emis-

sion limits. Since many of these ESPs

have been in operation for 30 to 50

years, many are in need of upgrades to

improve performance and reliability.

Even if a new pulse jet fabric filter will

be installed downstream of an ESP, an

ESP upgrade may be economical be-

cause the enhanced ESP could reduce

maintenance costs and preserve fly ash

sales. Many of the modern ESP designs

and controls can be installed in old

Authors

Bryant Purse is an AQCS Process En-gineer for Kiewit Power Engineers of Lenexa, Kansas. He develops perfor-mance testing procedures, equipment specifications, process calculations, and supports field performance testing, proposals, and client presentations.

Ray Zbacnik is an AQCS Process Spe-cialist for Kiewit Power Engineers of Lenexa, Kansas. Zbacnik has almost 40 years of chemical engineering experi-ence, which includes 20 years of AQCS experience in the power industry.

Mitchell Krasnopoler serves Kiewit Pow-er Engineers of Lenexa as the Manager of Air Quality. He has almost 25 years of engineering experience in air pollution control technologies; extensive experi-ence in flue gas desulfurization (FGD) design, operations and testing expertise and over 30 years of design experience for various fossil and nuclear power gen-eration projects.

1306pe_50 50 6/4/13 4:03 PM

Page 56: Power Engineering June 2013

www.power-eng.com 51

A complicating factor

with the MATS regula-

tions is that they impose

stricter limits on acid gas

and mercury emissions.

The regulations call for an

HCl emission limit of 0.002

lb/MMBtu and a mercury

emission limit of 1.2 lb/

TBtu. At many plants, tech-

niques to meet these new

limits include activated car-

bon injection (ACI) for mer-

cury removal and perhaps

dry sorbent injection (DSI)

or acid gas control. Plant

personnel must ensure that

the existing ESP can handle the addi-

tional particulate loading.

Changes in particulate loading from

ACI or DSI treatment are not the only

issue. Ash resistivity (the ability of the

ash to accept and transfer an electri-

cal charge) changes with the addition

of carbon or scrubber particulates.

Also, resistivity may be altered due to

changes in such operating conditions

as temperature, moisture, and chemi-

cal composition.

Sodium Ion Depletion:

Another issue that can drive ESP up-

grades is sodium ion depletion. This

phenomenon influences hot side ESP

performance with PRB as the fuel. The

nature of the PRB ash (low sodium,

low chloride, high ash), increases ash

resistivity and has forced some power

plants to de-rate the unit periodically

and shut it down for collection plate

washing. Mechanical rapping is sim-

ply not sufficient. Sodium depletion

occurs when positively-charged sodi-

um ions migrate towards the negative

charge of the ionizing electrodes and

form a sodium-rich layer in the col-

lected ash. This outer layer dislodges

by rapping, but the inner ash layer,

depleted of sodium ions, has different

characteristics making it much more

difficult to remove because of the re-

sistivity increase. The layer continues

to build, reducing the ability to apply

power to the field. Because sodium

depletion alters the chemical proper-

ties of the ash, an ESP upgrade may

not completely solve the problem, but

an upgrade may combat the decrease

in performance.

UPGRADE TECHNOLOGIES

Due to the above-mentioned fac-

tors and stricter environmental regu-

lations, many existing ESPs will have

to either be upgraded or converted to

fabric filter devices, aka baghouses. A

potential option at some plants may

even be a polishing fabric filter in-

stalled downstream of the existing

ESP. The configuration will be heav-

ily dependent upon the plant’s current

process conditions and the desired

outlet emissions. The most common

methods of improving an electrostatic

precipitator are:

• Upgrading the collection elec-

trodes

• Upgrading the discharge elec-

trodes

• Upgrading the rapping system

• Upgrading the transformer-rectifi-

er assemblies

• Improving the flow distribution

Other methods such as adjusting

the aspect ratio (the ratio of the ESP’s

effective height to the ESP’s effective

length) or fly ash/flue gas condition-

ing (altering the chemical/physical

characteristics of the fly ash) are less

common. Neither of these methods

will be discussed in this article.

Upgrading the Collection Elec-

trodes

Collection electrodes (CEs) typically

are of a plate design for dry ESPs. Tu-

bulare collection electrodes have been

utilized, but these are primarily for

wet ESP applications. In most cases,

mechanical rapping. The fly ash falls

to collection hoppers from which it is

then disposed.

REASONS FOR

ESP UPGRADES

A number of factors influence ESP

upgrades including performance deg-

radation, increased maintenance, poor

reliability, changes in particulate re-

sistivity, sodium ion depletion (pri-

marily for hot-side ESPs), volumetric

flow rate changes, increased inlet par-

ticulate loading (typically due to dry

sorbent injection), stricter emission

regulations and compliance protocols,

and even normal wear and tear such as

plate warping and leaks in the casing.

An ESP upgrade will improve perfor-

mance and reliability, which will re-

duce the plant’s operating costs in the

long run.

MATS Regulations

One of the primary drivers for ESP

upgrades is the EPA’s new Mercury and

Air Toxics Standards (MATS) regula-

tions. The MATS ruling established a

filterable particulate emission limit

of 0.03 lb/MMBtu based on EPA Test

Method 5.

An example of a rigid discharge electrode. Photo

courtesy of www.environmentawareness.com

1306pe_51 51 6/4/13 4:03 PM

Page 57: Power Engineering June 2013

www.power-eng.comFor info. http://powereng.hotims.com RS# 28

collection plates include stiffeners that act as baffles to

prevent particle re-entrainment. Properly designed collec-

tion plates eliminate excessive rapping and ensure equal

distribution of the rapping force throughout the plate.

Collection electrode design should be correlated with

the discharge electrode (DE) design. For ESPs with weight-

ed wire discharge electrodes, typical plate spacing is 6 to

12 inches. Many modern ESPs have rigid frame or plate

discharge electrodes, and in these designs the typical plate

spacing is 12 to 16 inches.

A common practice for upgrading an ESP is the altera-

tion of the plate spacing to increase the efficiency of the

unit. New collecting plates will restore DE-to-CE spac-

ing and alignment. New CEs may also improve rapping

efficiency by decreasing rapping density and allowing

increased rapping acceleration. Wider spacing along with

new power supplies will increase the voltage and power

input to the electric fields.

Upgrading the Discharge Electrodes

Discharge electrodes receive negative, high voltage,

direct current and generate the field that charges the en-

trained dust particles. A simple increase of applied volt-

age is not necessarily a good solution because of the threat

of spark-over between the discharge and collection elec-

trodes. Spark-over causes a short-term breakdown of the

electric field. It is important to design an ESP where spark-

ing does not occur too frequently. For well-designed ESPs,

sparking usually occurs between 50 and 100 times per

minute.

The discharge electrode should be designed to optimize

the induced electrical field, and should be customized

for the individual process. In the past, the weighted wire

design for the discharge electrode was common, but me-

chanical fatigue has caused operating problems. Although

most ESP vendors prefer the tube and pin electrode design,

other common rigid discharge electrodes should also be

considered, such as rigid masts and rigid frame electrodes.

Selection of modern discharge electrodes, per the cor-

rect requirements for the application, can greatly improve

ESP performance.

Upgrading the Rapping System

Rapping is the process by which a mechanically-induced

force is applied to the collections plates to dislodge the col-

lected ash.

For maximum efficiency, it is important to allow some

buildup of dust particles and not rap the plates too fre-

quently.

Plates are typically rapped once the dust layer reaches

a thickness range of 0.03 to 0.50 inches. Rapping in this

1306pe_52 52 6/4/13 4:03 PM

Page 58: Power Engineering June 2013

www.power-eng.com

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range prevents re-entrainment of ash.

One method to increase rapper efficiency is improve-

ment of the rapper controls, in part by setting proper rap-

ping frequencies.

The inlet collection plates need to be rapped more fre-

quently than those in the outlet fields. Also, rapping dis-

charge electrodes at a proper frequency to prevent dust

accumulation on these instruments is important. Fine-

tuning of existing rappers and controls may avoid the is-

sue, and cost, of installing new rappers.

Increasing the number of rappers will improve the rap-

ping system by enhancing the rapping energy. Modifica-

tion of rapper placement or by dedicating existing or new

rappers to fewer plates increases rapper density. Such op-

tions for an existing system should be evaluated before in-

vesting in completely new rappers.

Upgrading the Transformer-Rectifier Assemblies

A critical component of a precipitator is the high-voltage

equipment, consisting of a step-up transformer, a high-

voltage rectifier, and control metering and protection cir-

cuitry. The system must be designed to ensure adequate

power to the discharge electrodes without causing exces-

sive sparking.

Depending upon the required operating conditions of

the ESP, an upgrade can be as simple as modernizing the

T-R set.

However, before increasing the power to the unit, the

electrode design and plate spacing may be modified in-

stead. The most common upgrade utilizes a three-phase,

high frequency switch mode power supplies (SMPS), with

control system adjustment to prevent excessive spark-over.

This upgrade efficiently delivers power to the ESP, maxi-

mizes the average voltage of the ESP, and reduces the fre-

quency of sparking.

However, utilizing a switch mode power supply may not

be feasible for every application.

Improving the Flow Distribution

Maldistribution of flue gas flow can lead to degraded

performance of the ESP.

Variable flue gas flow changes the particle distribution

throughout the unit. Thus, some areas of the ESP may be

exposed to a greater gas flow and particulate loading that

exceeds local collection capabilities.

Flow distribution devices can be installed to normalize

the flows to all ESP chambers. Normalizing the flow will

prevent sneakage of untreated gas around the collecting

fields.

Physical and Computational Fluid Dynamic (CFD) model-

ing are tools for analyzing an ESP flue gas profile. The meth-

ods can help identify what devices are needed to optimize

1306pe_53 53 6/4/13 4:03 PM

Page 59: Power Engineering June 2013

www.power-eng.com

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be evaluated and studied.

This evaluation requires the follow-

ing:

• Understand boiler feed coal chem-

istry

• Study the physical and chemical

properties of the fly ash

• Evaluate the origi-

nal process design

conditions and cur-

rent operating con-

ditions

• Review the flue

gas profile/flow dis-

tribution

• Examine the ex-

isting ESP casing and internals for

corrosion

• Examine the structural integrity

of the ESP foundation

• Inspect ESP casing and compo-

nents for wear

• Evaluate the control systems

• Consider site layout/configuration

limitations

• Evaluate the ESP electrical system

and electrical characteristics of

the ESP.

References

“Steam, Its Generation and Use,” Chapter

33, “Particulate Control,” Babcock & Wil-

cox Company, Edition 41, Barberton, Ohio,

2005.

US Patent No. 895,729; “Art of Separating

Suspended Particles from Gaseous Bodies,”

Application Filed 9 July 1907. Awarded 11

August 1908.

http://www.google.com/pat-

ents/US895729

US EPA Technology Transfer Network,

“Particulate Matter Controls,” Section 6.

http://www.epa.gov/ttn/catc/

dir1/cs6ch3.pdf

the flue gas flow into, through, and out

of the precipitator.

CONCLUSION

As previously discussed, ESP up-

grades involve many different meth-

ods that can be optimized in part or

in whole. Emissions

testing provides the

ultimate indicator

that the performance

of the ESP may have

declined or that the

unit will not perform

to meet new regula-

tions.

However, the cause of performance

degradation may not always be clear.

Simply replacing one component

may not increase ESP efficiency. Due

to the complicated nature of precipita-

tor upgrades, the existing ESP should

One method to increase rapper efficiency is improvement of the rapper controls.- Kiewit Power Engineers

1306pe_54 54 6/4/13 4:03 PM

Page 60: Power Engineering June 2013

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Page 61: Power Engineering June 2013

www.power-eng.com56

must comply by Oct. 19, 2013.

The EPA estimates that over 900,000

CI engines and over 335,000 SI engines

will be affected.

This includes engines located in

both major and area sources of air tox-

ics emissions.

The compliance requirements vary

and are based on engine size, use of

engine, type of engine and source.

Although the regulation affects an esti-

mated 900,000 existing compression ig-

nited or diesel engines, almost 90 percent

of these engines will only be required to

meet best maintenance practices. How-

ever, a significant number of diesel and

dual-fuel engines will require the addi-

tion of emissions control catalyst to meet

the HAPs limits required by the RICE NE-

SHAP regulation.

Since the EPA has chosen carbon

monoxide (CO) as a surrogate for

the principal hazardous air pollutant

formaldehyde, this article focuses on

a project to reduce CO emissions from

diesel and dual-fuel engines.

In order to comply with the latest RICE

NESHAP Standards, the equipment in-

stallation requirements for nonemergen-

cy diesel and dual-fuel engines greater

than 500 horsepower typically include

the following:

• Catalyst housing with an oxidiza-

tion catalyst

• CPMS (continuous parametric

monitoring system)

• Crankcase ventilation system

• Use of ultra-low-sulfur-diesel

(ULSD) fuel

• Engine hour meter

• Limitations on engine start-up time

• Performance tests to demonstrate

engine emission compliance

Operators of stationary engines af-

fected by RICE NESHAP who are not in

compliance by the deadline dates can be

fined on a daily basis.

A one-year compliance extension can

be requested, but the request must be

made at least 120 days before the compli-

ance due dates.

BACKGROUND:

NRG APPLICATION

NRG Energy, a leading power gen-

eration company, operates a 12 MW

peaking plant near Harrisburg, Penn.

and needed to reduce the CO emis-

sions in order to comply with the RICE

NESHAP regulation.

In February 2010, the U. S. En-

vironmental Protection Agency

(EPA) issued a new national

emission standard for hazard-

ous air pollutants (HAPs) that

affected existing stationary diesel, dual-

fuel and gas engines.

This regulation, known as Reciprocat-

ing Internal Combustion Engine Nation-

al Emission Standard for Hazardous Air

Pollutants (RICE NESHAP) was finalized

in January 2013, but the original compli-

ance dates have not changed. Diesel and

dual-fuel compression ignition (CI) en-

gines must comply by May 3, 2013 and

natural gas spark ignited (SI) engines

Engineering Design for RICE NESHAP ComplianceBY STEPHEN R. NEWCOMB, P.E., RPA ENGINEERING; MARC ROST, JOHNSON MATTHEY STATIONARY EMISSIONS CONTROL LLC; RAY KULPA, SOLBERG MANUFACTURING; AND BARD RUPP, NRG ENERGY

NRG Energy RICE NESHAP installation at Harrisburg, Penn., showing catalyst housing (left) and crankcase ventilation system (right).

1306pe_56 56 6/4/13 4:04 PM

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www.power-eng.com 57

SCOPE REQUIREMENTS

FOR NRG ENERGY

PAXTON PLANT

Oxidation catalyst

The oxidation catalyst systems in-

stalled at NRG were furnished by John-

son Matthey Stationary Emissions Con-

trol LLC and designed to meet the RICE

NESHAP emissions limit for CO emis-

sions. For CI engines larger than 500 HP

at either area sources or major sources,

this limit is either an absolute emission

limit of 23 ppmvd CO at 15 percent O2 or

a 70 percent reduction of CO emissions.

The catalyst that was used for each

engine was a combination of Platinum

Group Metals (PGM) on a stainless steel

metal monolith. The monolith was sup-

plied in block-sized modules, and these

blocks were inserted in carbon steel hous-

ings, with one housing for each of the two

engines. The catalyst

blocks were arranged

in a single layer, with

the weight of each

block being limited to

50 pounds to facilitate

installation and removal from the cata-

lyst housing.

Each of the catalyst housings was

equipped with a hinged door to pro-

vide access to the catalyst blocks from

an adjacent walkway. The housings were

installed outside of the generator building

and were externally insulated to reduce

heat loss. Each of the housings included

spare catalyst tracks for future use should

environmental regulations become more

stringent. The catalyst tracks are designed

to float within the housing to compen-

sate for thermal expansion and to seal

the catalyst modules to prevent exhaust

gas from bypassing the catalyst.

The engine exhaust flow rates, tem-

peratures and emissions were measured

in previous exhaust stack testing, and

these values were used as the design ba-

sis for this project. Although the current

CO emission values were not available,

the oxidation catalyst will convert CO

to carbon dioxide (CO2) by the design

reduction efficiency based on the proper

selection of the catalyst’s gas hourly space

velocity regardless of the amount of CO

in the engine exhaust.

According to the RICE NESHAP Rule,

the minimum and maximum tempera-

ture limits for lean burn CI engines is

450°F and 1350°F, respectively. The

minimum temperature is required for

the catalyzed reaction to occur; the upper

temperature limit avoids thermal sinter-

ing of the catalyst. The measured exhaust

temperatures of these engines from the

previous testing were typically within the

limits of the Rule at 500°F to 750°F from

During 2012, NRG worked with RPA

Engineering (RPA), a leading, full-service

engineering firm based in Wyomissing,

Pa. to specify, design and install an oxi-

dation catalyst and associated equipment

to meet RICE NESHAP requirements.

Engine operation

The NRG Energy Center Paxton

peaking plant is comprised of two

Cooper-Bessemer LSVB-20-GDT CI

engines that were installed in 1986.

Each engine is rated at 8656 bhp and

generates 6 MW of electricity.

NRG can operate these engines on full

diesel fuel for a limited amount of hours,

or dual-fuel (which is comprised of ap-

proximately 95 percent natural gas and 5

percent pilot diesel oil).

The engines are started on diesel fuel

and are switched over to dual-fuel opera-

tion at approximately one-third load.

NRG operates the engines on dual-fuel

because of the current cost advantages of

natural gas, but NRG also has the capabil-

ity to operate on diesel fuel only should

this be desired.

The Cooper-Bessemer engines at NRG

had been previously modified to sub-

stantially reduce the emissions of NOx in

the engine exhaust compared to an un-

modified dual-fuel engine.

Engine No. 1 is equipped with an

AMPS System and Engine No. 2 is

equipped with a

Cooper Clean Burn

System.

RICE NESHAP re-

quires that engine’s

time spent at idle be

minimized and that the engine startup

be limited to a period needed for ap-

propriate and safe loading of the en-

gine, not to exceed 30 minutes, after

which time the non-startup emission

limitations apply.

The catalyst used for the engines was a combination of

Platinum Group Metals on a stainless steel metal monolith,

with the catalyst blocks arranged in a single layer and the

weight of each block limited to 50 pounds.

Operators not in compliance with RICE NESHAP can be fined daily.

1306pe_57 57 6/4/13 4:04 PM

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www.power-eng.com58

operators are installing open systems

to prevent the ingestion of raw blow-by

into the engine turbocharger or exhaust.

While the EPA does not specifically man-

date an efficiency level, best practices dic-

tate that all visible emissions are elimi-

nated from the crankcase vent.

This is only possible with a high effi-

ciency filter and not with the traditional

wire mesh.

In the case of NRG, Solberg Manufac-

turing Inc. designed and delivered a high-

efficiency, open crankcase ventilation

system to capture the vented hazardous

blow-by emissions from each of the two

existing Cooper-Bessemer engines. The

Solberg system includes an internal air/

oil separator cartridge with an efficiency

of 99.97 percent for 0.3 micron particles

and oil mist. This is packaged with a vac-

uum source, custom piping and a valve

to allow NRG to maintain the natural

crankcase pressure of the engine. The oily

emissions are pulled through the car-

tridge, and the entrained oil is coalesced

and collected at the bottom of the canis-

ter. The collected oil is recovered through

a drain port and is scavenged to a waste

oil tank inside the building. The result is

clean air and no visible emissions vented

from the crankcase to atmosphere.

Additional requirements

The engines were already equipped

with non-resettable hour meters, and

they were not required to be added to

the NRG installation to meet compli-

ance requirements. NRG was required

to use ultra-low-sulfur-diesel fuel as

part of the installation of the catalytic

oxidation system.

CHALLENGES

The RICE NESHAP installation at the

NRG Energy Paxton Plant presented sev-

eral major, but not uncommon, challeng-

es to the project team. The team worked

together to overcome these challenges as

described below.

Space limitations

The configuration of the existing

engine installation did not leave much

room for the installation of the cata-

lyst housing or the crankcase ventila-

tion system in an accessible location.

The exhaust system for each engine in-

cluded an existing, but out-of-service,

heat recovery steam generator (HRSG)

and an exhaust silencer.

Catalyst location options

Initially, NRG and RPA considered

three options for the catalyst location.

The most open area in the existing instal-

lation was the 36-inch diameter exhaust

pipe between the HRSG and the silencer.

One problem with this location was that

it would require platform modifications

to provide access to the catalyst. Another

problem was that replacement of the ex-

isting HRSG with a new operating unit

would cause catalyst inlet temperatures

too low for catalytic oxidation.

NRG and RPA also considered a loca-

tion inside the generator building be-

tween the expansion joint and the HRSG

inlet. This location would have required

new platforms for access and modifica-

tions to the building structure.

The third option, which required more

initial cost to implement, was to remove

the existing out-of-service HRSG and

place the catalyst housing in a location

just outside the generator building wall.

start-up to full load operation.

Continuous parametric monitor-

ing system (CPMS):

The RICE NESHAP Rule requires the

catalyst inlet temperature (as based on

a four-hour rolling average) to be docu-

mented and maintained within the mini-

mum and maximum operating tempera-

ture limitations noted above. The Rule

also requires that the pressure drop across

the catalyst be measured once per month

to demonstrate that it is maintained with-

in a +/- 2-inch w.c. tolerance (as measured

during the initial performance test).

NRG collects and stores the data with a

Johnson Matthey HapGuard Continuous

Parametric Monitoring System.

CPMS data readings are acquired at

least every five minutes. The CPMS calcu-

lates and stores a one-hour and four-hour

rolling average of temperature and differ-

ential pressure data for a minimum of 12

months. The CPMS will initiate an alarm

signal when temperature or pressure

readings and calculations exceed the lim-

its set by the operator. The operator has

the provision to define alarm set points

and unit identification during the system

commissioning.

There is a dedicated, programmable

CPMS for each engine’s catalytic con-

verter, which is installed in a NEMA 4

enclosure near the catalyst housing for

each engine. The CPMS is programmable

from a keypad on the front panel display.

Real time catalyst inlet temperature and

differential pressure are displayed on the

front panel display. The CPMS communi-

cates acquired data, calculated data and

monthly reports to NRG’s plant comput-

er by Ethernet connection.

Crankcase ventilation system:

RICE NESHAP specifically requires

that each diesel engine must have a

crankcase ventilation system to capture

the hazardous blow-by emissions vented

from the crankcase during operation.

These emissions consist of oil mist, met-

als and other particulate emissions.

Open or closed systems are accept-

ed under the standard; however, most

The NRG Energy Center Paxton peaking

plant, a 12 MW peaking plant plant located

near Harisburg, Penn., needed to reduce CO

emissions to comply with the RICE NESHAP

regulation.

1306pe_58 58 6/4/13 4:04 PM

Page 64: Power Engineering June 2013

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Page 65: Power Engineering June 2013

www.power-eng.com60

catalyst housing during operation.

The longer run of exhaust pipe created

by the removal of the existing HRSG led

to greater thermal expansion in the ex-

haust pipe between the catalyst housing

and the silencer. This was resolved by

adding a new fabric expansion joint de-

signed to compensate for four inches of

thermal expansion.

SYSTEM PRESSURE

LIMITATIONS

Catalyst pressure drop

Another concern with the catalyst

housing design was the maximum pres-

sure drop across the catalyst that could

be allowed before affecting engine per-

formance. The NRG Cooper-Bessemer

LSVB-GDT-20T engine has a maximum

allowable backpressure of 20-inches

w.c. Most of this pressure allowance was

already used up by the existing compo-

nents in the engine exhaust pipe.

In order to determine the maximum

pressure drop that could be allowed for

the catalyst, RPA Engineering modeled

the engine exhaust system and ran sev-

eral different exhaust flow conditions to

determine the maximum allowable de-

sign pressure drop for clean catalyst. The

pressure drop allowance also needed to

compensate for “dirty” conditions.

The standard catalyst housing design

used by Johnson Matthey was custom-

ized after computational fluid dynamic

modeling indicted that uniform flow

across the catalyst face could be achieved

with minimal inlet and outlet

transitions between the exhaust

pipe and the catalyst housing.

The compactness of the catalyst

housing combined with the rel-

atively stringent allowable pres-

sure drop limitation resulted in

a unique housing configuration

that fit within the existing ex-

haust system design.

Crankcase Pressure Re-

quirement

The NRG Cooper-Bessemer

engines are designed to operate

with a slightly positive crank-

case pressure to reduce the pos-

sibility of an explosion. This im-

pacted the design of the required

crankcase ventilation system.

The Solberg recirculation system in-

corporates a regenerative blower to cre-

ate suction to overcome the differential

pressure created by the oil saturated filter

element. However, the systems integrat-

ed piping will recirculate the exhaust air

from the blower back to the inlet of the

crankcase ventilation system. The result is

an equilibrium state in which the natural

engine crankcase pressure is maintained.

A manual control valve was included to

restrict the recirculation air over time

and produce a slight vacuum, if neces-

sary, to overcome eventual leaks through

worn engine seals. The NRG operators

monitor crankcase pressure on a regular

basis. Due to the concern with an upset

condition leading to the possibility of

NRG and RPA determined that the exist-

ing platform could be easily modified to

provide access to the new catalyst hous-

ings and also determined that there was

sufficient space to allow the installation

of a new HRSG, if needed.

After careful deliberation, NRG pro-

ceeded with the third option. Due to the

fact that space needed to be maintained

for a possible future HRSG, the

allowable length that the cata-

lyst housing took up in the ex-

haust duct was more limited.

Crankcase ventilation lo-

cation options

Another concern was de-

termining a location for the

crankcase ventilation system.

The engine crankcase is vented

through a six-inch pipe to a lo-

cation just outside the generator

building. A separate two-inch

cylinder head vent pipe joins the

main six-inch crankcase vent

pipe at a location just above the

engine. The high elevation at

which the crankcase vent pipe

ran inside the building made it

difficult to select a location that

would provide operator access

for system maintenance and ad-

justment.

The decision to remove the existing

HRSG contributed to finding an accessi-

ble location for the crankcase ventilation

system outside the generator building on

the existing platform. The Solberg crank-

case ventilation system also was able to

be customized to meet installation re-

quirements, and the units were mirror

images of each other.

Other factors

The selected location of the catalyst

immediately downstream of an exist-

ing metal bellows expansion joint raised

concerns about the resultant force that

would be imposed on the catalyst hous-

ing. Johnson Matthey performed a finite

element analysis to verify that this force

would not lead to excessive stress in the

A dedicated continuous parametric monitoring

system communicates information to the plant’s

computer using an Ethernet connection.

1306pe_60 60 6/4/13 4:04 PM

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www.power-eng.com 61

For info. http://powereng.hotims.com RS# 33

the engines to operate at the desired

crankcase pressure of 0.4 to 0.5-inches

w.c. While the installation presented

some challenges, the equipment was

successfully installed through a coop-

erative effort among all members of

the team.

negative pressure in the engine crank-

case, a pressure switch was installed on

the engine that would alarm in case of

a low positive pressure in the engine

crankcase.

SYSTEM START-UP

The RICE NESHAP equipment was in-

stalled at the NRG Energy Paxton Plant

in the fall of 2012. The RICE NESHAP

systems for each engine were started up

in November 2012 by representatives of

Johnson Matthey and Solberg Manufac-

turing. During start-up the crankcase

ventilation system functioned as intend-

ed and there was no visible discharge

from the crankcase ventilation vent pipe.

Sample analysis for CO emissions

using a Testo 350 portable gas analyzer

were taken at 58 percent load, 67 percent

load, 83 percent load and 100 percent

load with Engine No. 1 operating on

dual fuel. As expected, the untreated CO

emissions at the engine outlet were the

highest at the lower engine loads. Un-

treated CO emissions decreased as the

engine load increased. The measured

CO conversion efficiency recorded the

highest CO conversion rate of 97percent

at the lower engine load, which then lev-

eled off at 95 percent CO conversion ef-

ficiency at full load. During the sample

testing, CO emissions at the outlet of the

catalyst had reached a plateau at an ab-

solute value of approximately 25 ppm,

regardless of the CO concentration at the

inlet of the catalyst.

CONCLUSION

The new RICE NESHAP regulation

has placed a significant requirement

on existing CI engines to reduce HAPs.

Using CO as a surrogate for HAPs, the

RICE NESHAP regulation required the

NRG engines to reduce CO emissions

by at least 70 percent or to a level of

23 ppmvd at 15 percent O2. NRG in-

stalled a precious metal-based cata-

lytic converter system to comply with

these emission limits. Emissions

testing with a lower span CO cell to

measure the CO conversion at low

CO concentrations showed that these

emission limits were achieved. The

addition of the crankcase ventilation

filters removed all visible emissions at

the crankcase vent pipe while enabling

1306pe_61 61 6/4/13 4:04 PM

Page 67: Power Engineering June 2013

www.power-eng.com62

from happening. In the absence of tur-

bine technology that provides high fish

passage on its own, hydro plant owners

must rely on such alternative measures as

spill or bypasses to protect fish.

To help overcome this problem, the

Electric Power Research Institute (EPRI),

U.S. Department of Energy (DOE), Alden

Research Laboratory Inc., Voith Hydro

Inc. and several industry partners have

been working to advance design of a

“fish-friendly” turbine. This turbine has

been conceptualized, tested using physi-

cal scale and computational fluid dy-

namics modeling, redesigned, produced

at model scale, and tested again. As a

result of this work, the Alden turbine is

now ready for installation and testing at a

hydroelectric plant, and efforts are under

way to find an industry partner to accom-

plish this next step.

UNDERSTANDING

THE BACKGROUND

Four years of work have gone into

a collaborative research and develop-

ment project funded by EPRI, DOE and

hydropower industry partners such as

Brookfield Renewable Power, Dairyland

Power Cooperative, Electricite de France,

New York Power Authority, New York

State Energy Research and Development

Authority, Puget Sound Energy, SCANA

Corp. and Southern Company. The ob-

jective of this project was to complete the

developmental engineering required for

the “fish-friendly” turbine developed by

Alden to prepare it for full-scale deploy-

ment and testing.

In 2009, EPRI, in response to a 2008

DOE funding opportunity announce-

ment with cost-sharing support from

the hydropower industry, was awarded a

$1.2 million DOE grant, matched by an

equal amount from EPRI and its industry

partners, to conduct engineering devel-

opment and physical scale model perfor-

mance testing of the Alden turbine. The

developmental engineering included:

• Using computational fluid dynam-

ics (CFD) to convert a conceptual

design into a design from which the

turbine can be built; and

• Constructing and testing a physical

model of the turbine to evaluate its

performance characteristics for eco-

nomic analysis.

The Alden turbine was developed

through DOE’s former Advanced Hydro

Turbine Systems Program and, more

recently, through EPRI’s Waterpower

Over four years, mul-

tiple entities within

the hydropower in-

dustry have worked to

advance design, con-

struction and installation of a specific

“fish-friendly” turbine design. Efforts are

under way to find a hydroelectric project

operator to install this unit and demon-

strate its effectiveness for safely passing

fish and producing electricity.

In an ideal operating scenario, every

drop of water available to a hydroelectric

powerhouse is run through the turbines

to generate electricity. However, the need

to support high fish passage survival at

most hydropower facilities precludes this

Development Statusof the Alden

“Fish-Friendly” TurbineBY NORMAN PERKINS, DOUGLAS A. DIXON, RAJESH DHAM AND JASON FOUST

This 1:8.71 physical model of the Alden

turbine runner was tested by Voith Hydro and

provided peak efficiency of 91.85%, which

translates to a maximum calculated prototype

efficiency of 93.64%.

1306pe_62 62 6/4/13 4:04 PM

Page 68: Power Engineering June 2013

www.power-eng.com 63

#

FEA Image ofTurbine Runner 1

Finite element analysis of the turbine runnerwas performed to determine the staticstresses for the stay vanes, wicket gatesand runner modifcations.

#

CFD Imageof Turbine Runner 2

Computational fuid dynamics simulations of theturbine runner included everything from thepenstock to the draft tube outlet and tailwater.The same loss sources were modeled here aswere studied using the physical model.

production, and finally reduced supply

costs. Although the runner is being de-

veloped to provide a new family of fish-

friendly hydro turbines for smaller ma-

chines across a range of head and flow

applications, Alden and Voith Hydro fo-

cused the design effort for potential pilot

application at a project with operating

conditions corresponding to 92 feet of net

head with a discharge rate of 1,500 cubic

feet per second (cfs).

Calculations show that the improved

flow environment through the final tur-

bine is expected to produce significant ef-

ficiency improvements (5% at the design

conditions listed above) with the same

or slightly improved fish-friendly char-

acteristics as compared with the original

Alden concept. While some small perfor-

mance improvements are predicted for

the final distributor, the majority of the

efficiency improvement is realized in the

final runner and draft tube as a result of

the improved runner-draft tube interac-

tion at the selected design condition.

After the modified turbine hydraulic

passageways were defined and structural

analysis was performed for the anticipat-

ed operating range, the hydraulic shapes

were released for model manufacture,

including the inlet pipe, transition piece,

spiral case, stay ring, wicket gates, runner

and draft tube. Physical model testing

was conducted in 2010 at Voith Hydro’s S.

Morgan Smith Memorial Hydraulic Lab-

oratory in York, Pa. Data was collected

on performance, thrust, runaway speed,

pressure pulsations, minimum pres-

sures, cavitation and wicket gate torques

to characterize the hydraulic behavior of

the turbine and identify the acceptable

operating range for the target site design.

Results of the hydraulic testing also

were incorporated into the final sizing of

the mechanical equipment. Voith Hydro

manufactured the physical model at a

scale of 1:8.71 and conducted the tests at a

speed of 900 rpm. During testing, a mod-

el peak efficiency of 91.85% was record-

ed. The prototype efficiency adjustment

translates into a maximum calculated

relatively thick semi-circular entrance

edges to minimize strike damage to fish,

extremely long blades with nearly 180 de-

grees of blade wrap, and a runner height

that is larger than a conventional turbine

of similar diameter. Each blade is fixed

to a central hub (crown) and an external

shroud (band), eliminating all gaps and

resulting leakage vortices within the run-

ner passage.

Runner geometry was evaluated ac-

cording to three distinct design criteria,

with fish friendliness being the most

important, followed by increased power

Program and DOE’s Wind & Water Power

Program. The turbine was designed to

support high fish passage survival, which

would offset the need for measures —

such as intake screens, fish passage spills

and alternative downstream fish by-

passes — that are expensive and decrease

generation. To reduce injury to fish, the

Alden runner has: only three blades, no

clearances between the blades and the

crown or housing, and, with the excep-

tion of small areas around the blade lead-

ing edges, pressure and velocity (shear)

gradients that meet established bio-crite-

ria for safe fish passage.

Before 2009, numerous studies sup-

ported by DOE, EPRI and industry col-

laboration were conducted to validate

the theoretical concept of the turbine.

Studies included: CFD modeling, use of

a one-third-scale test facility to evaluate

the turbine biological and engineering

performance, additional conceptual tur-

bine development efforts (in 2006), and

laboratory experiments that examined

the relationship between turbine blade

leading edge geometry and fish injury/

survival after blade strike.

HYDRAULIC

DEVELOPMENT

The Alden runner reduces blade strike

mortality through several modifications:

• Reducing the number of blades rela-

tive to conventional applications;

• Employing special blade leading

edge geometries; and

Rotating slower than conventional tur-

bines. The current Alden turbine design

incorporates a runner that features three

blades that rotate at a speed of 120 revo-

lutions per minute (rpm). Application of

conventional turbine technologies for

the target site results in a 13-bladed Fran-

cis turbine that rotates at 189.5 rpm, or a

five-bladed Kaplan turbine that rotates at

267.9 rpm.

The blade shapes were developed to

meet criteria for pressure change rates,

shear rates and minimum pressures

through the runner. The blades feature

1306pe_63 63 6/4/13 4:04 PM

Page 69: Power Engineering June 2013

www.power-eng.com64

Anticipated Range of Application for Alden Turbine 3

The Alden turbine design represents a new family with a range of head and fow applications.Future design modifcations are anticipated to extend operation of the turbine above120 feet of net head.

compared. The CFD hill chart is gener-

ally similar in shape to that derived from

the physical model test results. However,

the CFD model tended to over-predict

efficiency for low flows with small gate

opening angles.

This resulted in displacement of the

CFD-derived highest efficiency area to

lower flows.

The reasons for these differences are

not clear.

It may be noted that the plotted ef-

ficiency contours are at intervals of only

0.5%, which accentuates visual differenc-

es between the contours from the CFD

and physical data.

The peak efficiency of 93.6% expected

for the full scale turbine was well-pre-

dicted by the CFD simulations. It is con-

cluded that the CFD simulations are most

reliable in predicting the more controlled

(coherent) flow patterns near the turbine

design point.

This direct comparison between CFD

simulations and physical model test data

provides useful information for turbine

designers and researchers.

This kind of validation allows the de-

veloped CFD model to be used to explore

other issues of concern, such as deter-

mining values for local pressures, pres-

sure change rates, shear and the locations

where related fish survival criteria are

met or exceeded.

prototype efficiency of 93.64%.

The final aspect of the developmental

engineering included the design for the

supporting mechanical and balance of

plant equipment for supply of the com-

plete unit. In this phase, finite element

analysis (FEA) was performed to deter-

mine the static stresses for the stay vanes,

wicket gates and runner modifications

(see Figure 1). Mechanical design and

analysis of the final spiral case and stay

ring decks was completed.

CFD SIMULATIONS

AND COMPARISON

WITH PHYSICAL

MODEL DATA

The data on efficiency and

power obtained from the physical

model testing, scaled up to proto-

type values, were used to compile

the “hill chart” to visually show

the best efficiency point (BEP)

and range of acceptable operat-

ing conditions. CFD simulations

of the entire turbine (see Figure 2)

were initiated, from the penstock

to the draft tube outlet and tail-

water. These simulations included

the fluid-filled spaces between

the outer runner shroud and the casing,

as well as between the head cover and

runner top, thereby including the same

loss sources as in the physical model.

Plotting the resulting efficiencies from

the physical model and CFD simulations

using non-dimensional head and flow

coefficients, which included the turbine

diameter and runner rotating speed, aid-

ed a direct comparison between the BEP

operating conditions and maximum effi-

ciency value. The general shape of the ef-

ficiency lines on the “hill chart” was also

Source:

Price of Alden vs Conventional Turbines 1

Alden Turbine

Conventional Francis Turbine (Same Power)

Conventional Kaplan Turbine (Same Power)

Diameter (mm) 3,900 2,510 2,650

Maximum Power (MW) 13.6 13.6 13.6

Turbine Cost 1 0.5 0.55

Generator Cost 0.8 0.65 0.65

Installation andCommissioning Cost

0.25 0.25 0.25

Automation/Balanceof Plant Cost

0.25 0.25 0.25

Relative Cost 2.3 1.65 1.7

Premium for Alden 39% 35%

1306pe_64 64 6/4/13 4:04 PM

Page 70: Power Engineering June 2013

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Page 71: Power Engineering June 2013

www.power-eng.com66

funding opportunity announcement,

EPRI was selected to receive $1.5 mil-

lion of support with a cost-share match

requirement to install and test the Al-

den turbine at a site to be determined.

References

Additional Tests Examining Survival of Fish

Struck by Turbine Blades, EPRI, Palo Alto, Calif.,

2011.

Amaral, S.V., et al, “Effects of Leading Edge

Turbine Blade Thickness on Fish Strike Survival

and Injury,” Proceedings of HydroVision 2008,

HCI Publications, Kansas City, Mo., 2008.

Cook, T.C., et al, Final Report – Pilot Scale

Tests Alden/Concepts NREC Turbine, prepared

by Alden Research Laboratory for U.S. De-

partment of Energy, Contract No. DE-AC07-

99ID13733, 2003.

Coulson, S., et al, “Alden Fish Friendly Tur-

bine: Final Development for Commercial Ap-

plication,” Proceedings of HydroVision 2011,

PennWell Corporation, Tulsa, Okla., 2011.

Demonstration Development Project: So-

licitation and Selection of a Site to Test a Fish-

Friendly Hydropower Turbine, EPRI Technical

Update No. 1022538 prepared by Alden Re-

search Laboratory, 2011.

EPRI-DOE Conference on Environmentally-

Enhanced Hydropower Turbines: Technical

Papers, EPRI, Palo Alto, Calif., and U.S. Depart-

ment of Energy, Washington, D.C., 2011.

Evaluation of the Effects of Turbine Blade

Leading Edge Design on Fish Survival, EPRI Re-

port No. 1014937 prepared by Alden Research

Laboratory, 2008.

“Fish Friendly” Hydropower Turbine Devel-

opment and Deployment: Alden Turbine Pre-

liminary Engineering and Model Testing, EPRI

Report 1019890 prepared by Alden Research

Laboratory, 2011.

Hecker, G.E., and T.C. Cook, “Development

and Evaluation of a New Helical Fish Friendly

Hydro-Turbine,” Journal of Hydraulic Engineer-

ing, Volume 131, No. 10, October 2005, pages

1-21.

Redesign of the Alden/Concepts NREC He-

lical Turbine for Increased Power Density and

Fish Survival: Evaluation of a Conceptual Proto-

type Turbine, EPRI, Palo Alto, Calif., 2009.

ALDEN TURBINE

DEVELOPMENT: PRICING

AND SCHEDULE

Below is a preliminary schedule for in-

stallation at a potential test site:

• Definition of unit layout, four

months from contract award from

the potential utility to Voith Hydro;

• Embeds arrive at site, 14 months

from contract award;

• Powerhouse crane available for Voith

Hydro use, 22 months from contract

award; and

• Equipment commissioned and

handover to owner, 28 months from

contract award.

The Alden turbine is, by design, lower

in power density than conventional tur-

bines.

The larger, more slowly rotating equip-

ment leads to a relatively more expensive

turbine-generator solution. For the site

conditions at a comparable prototype

site, sizing for a conventional Francis unit

gives a 13-bladed, 2.5-meter-diameter

runner with an rpm of 189.5. Sizing for a

conventional Kaplan turbine gives a five-

bladed, 2.7-meter-diameter runner with

an rpm of 276.9. During the Alden tur-

bine development, a detailed cost study

was performed to determine the equip-

ment, installation and commissioning

cost.

Table 1 provides a comparison of the

installed equipment price for the Alden

turbine vs. conventional hydro turbines.

The prices are normalized relative to the

Alden turbine.

The relative pricing does not include

civil work. The larger size and slower

speed of the turbine allows for a higher

setting relative to the tailwater.

For the prototype design, the Alden

distributor centerline is 5 feet above tail-

water, while the conventional Francis

centerline is anticipated to be set 2 feet

above tailwater.

The conventional Kaplan centerline

is set the lowest, falling 16 feet below

tailwater.

The higher setting of the Alden turbine

may result in less excavation and lower

civil costs.

APPLICABILITY TO

OTHER HYDRO SITES

Although the turbine was hydraulical-

ly and mechanically designed for a target

site condition, it represents a new turbine

family with a range of head and flow ap-

plications. Figure 3 shows the anticipated

turbine application range.

The green region, labeled “current ap-

plication,” spans 75 to 100 feet of net

head and represents the head range cov-

ered by the current design. The larger yel-

low region, labeled “modified current ap-

plication,” can be accomplished through

appropriate sizing and design modifica-

tions to the turbine. This region spans

from 30 to 120 feet of net head. At 120

feet of net head, stress limitations of the

current design limit applicability. It is an-

ticipated that future design modifications

to the turbine can extend the operation

above 120 feet of net head. Below 30 feet

of net head, turbine application switches

to large bulb units.

SUMMARY AND

NEXT STEPS

The work performed to date has im-

proved the performance characteristics

of the Alden turbine while maintaining

its fish-friendly characteristics.

The preliminary engineering re-

quired to make the turbine commer-

cially available has been completed.

Design modifications to the turbine

components have improved efficiency

to almost 94% at the selected design

point, while providing the same or

slightly improved fish passage survival.

These turbine modifications were also

selected to decrease manufacturing and

supply costs, resulting in a solution that

is economically competitive with con-

ventional turbines. The improved tur-

bine is now available for commercial

deployment.

In 2011, in response to another DOE

1306pe_66 66 6/4/13 4:04 PM

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http://www.dteenergy.com/dteEnergyCompany/careers/

ELECTRICAL ENGINEER

For info. http://powereng.hotims.com RS# 456

WE ARE BUYING!!!

ARE YOU SELLING?

VALVES

INSTRUMENTATION

ELECTRICAL CONTROLS

PROCESS EQUIPMENT

PROCESS CONTROLS

PLANT MACHINERY

PSA SNUBBERS, ETC.

VISITwww.FerncroftManagement.com

email:[email protected]

T. 978-815.6185 Fax. 603-814.1031

FerncroftManagement,LLC

LIMITORQUE OPERATORS WANTED NOISE?���������������������������������

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Houston: 713-789-9400

Calgary: 403-259-6600

www.HFPacoustical.com

[email protected]

For info. http://powereng.hotims.com RS# 451

For info. http://powereng.hotims.com RS# 458

FIND CONDENSER LEAKS FAST WITH FOAM METHOD LEAK DETECTION, TUBE PLUGS IN STOCK

John R. Robinson Inc.Ph# 800-726-1026

Condenser & Heat Exchanger Toolswww.johnrrobinsoninc.com

For info. http://powereng.hotims.com RS# 452

Get a thorough mix with:

Pugmill Systems, Inc.P.O. Box 60

Columbia, TN 38402 USA

Ph: 931-388-0626 Fax: 931-380-0319

www.pugmillsystems.com

For info. http://powereng.hotims.com RS# 457

Intralox, L.L.C. is looking for an energetic, well organized person with the ability to evaluate market opportunities, distil clear messages, and execute selling strategies. The qualified individual will be responsible for calling on accounts at the corporate and plant level in the development and implementation of sales strategies with emphasis on institutional conversions for multi-plant corporations. Must have an industrial sales background preferably in the electrical power, petro-chemical or steel industry and be willing to travel up to 70%.

For more position details and to apply, visit www.intralox.com.

NATIONAL ACCOUNTS MANAGER

For info. http://powereng.hotims.com RS# 455

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For info. http://powereng.hotims.com RS# 465

1319 Macklind Ave., St. Louis, MO 63110 Ph: (314) 781-6100 / Fax: (314) 781-9209

www.ampulverizer.com / E-Mail: [email protected]

Quality and Service Since 1908

Ring Granulators, Reversible Hammermills,

Double Roll Crushers, Frozen Coal Crackers

for crushing coal, limstone and slag.

For info. http://powereng.hotims.com RS# 463

�����������������������������������������

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For info. http://powereng.hotims.com RS# 466

24 / 7 EMERGENCY SERVICE

BOILERS20,000 - 400,000 #/Hr.

DIESEL & TURBINE GENERATORS50 - 25,000 KW

GEARS & TURBINES25 - 4000 HP

LARGEST INVENTORIES OF:

Air Pre-Heaters • Economizers • DeaeratorsPumps • Motors • Fuel Oil Heating & Pump Sets

Valves • Tubes • Controls • CompressorsPulverizers • Rental Boilers & Generators

847-541-5600 FAX: 847-541-1279 visit www.wabashpower.com

FOR SALE/RENT

POWER

EQUIPMENT CO.

444 Carpenter Avenue, Wheeling, IL 60090

wabash

For info. http://powereng.hotims.com RS# 459

For info. http://powereng.hotims.com RS# 461

For info. http://powereng.hotims.com RS# 464

GEORGE H. BODMAN, INC.Chemical cleaning advisory services for

boilers and balance of plant systems

George H. BodmanPres / Technical Advisor

P.O. Box 5758 Office (281) 359-4006Kingwood, TX 77325-5758 1-800-286-6069email: [email protected] Fax (281) 359-4225

For sale or rent

The world’s verybest portable end

prep tools and abrasive saws

800-343-6926www.escotool.com

Tur bine ControlsWoodward, GE, MHC

Parts and ServiceObsolete Parts Inventory

Control System, ModernizationTraining, Troubleshooting

(610) [email protected]

TurboGen Consultants, Inc.

For info. http://powereng.hotims.com RS# 462

For info. http://powereng.hotims.com RS# 460

rental

equipment

the steam & power special forces®

1-800-990-0374

www.rentalboilers.com

Rental Boilers • Deaerator Systems •

Economizers • Water Softener Systems •

24-Hour Emergency Service

1306pe_71 71 6/4/13 4:05 PM

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www.power-eng.com72

INDEX

RS# COMPANY PG# SALES OFFICERS# COMPANY PG#

1421 S. Sheridan Rd., Tulsa, OK 74112Phone: 918-835-3161, Fax: 918-831-9834e-mail: [email protected]

Sr. Vice President NorthAmerican Power Group Richard Baker

Reprints Foster Printing Servive4295 Ohio StreetMichigan City, IN 46360Phone: 866-879-9144e-mail: [email protected]

National Brand Manager Rick HuntzickerPalladian Professional Park3225 Shallowford Rd., Suite 800Marietta, GA 30062Phone: 770-578-2688, Fax: 770-578-2690e-mail: [email protected], AR, DC, FL, GA, KS, KY, LA, MD, MO,MS, NC, SC, TN, TX, VA, WV

Brand Sales Manager Dan Idoine806 Park Village DriveLouisville, OH 44641Phone: 330-875-6581, Fax: 330-875-4462e-mail: [email protected], DE, IL, IN, MA, ME, MI, NH, NJ, NY,OH, PA, RI, VT, Quebec, New Brunswick,Nova Scotia, Newfoundland, Ontario

Brand Sales Manager Tina Shibley1421 S. Sheridan RoadTulsa, OK 74112Phone: 918-831-9552; Fax: 918-831-9834e-mail: [email protected], AZ, CA, CO, HI, IA, ID, MN, MT, ND,NE, NM, NV, OK, OR, SD UT, WA, WI, WY,Alberta, British Columbia, Saskatchewan,Northwest Territory, Yukon Territory,Manitoba

International Sales Mgr Anthony OrfeoThe Water TowerGunpowder MillsPowdermill LaneWaltham Abbey, Essex EN9 1BNUnited KingdomPhone: +44 1992 656 609, Fax: +44 1992 656 700e-mail: [email protected], Asia, Central America, Europe,Middle East, South America

European Sales Asif YusufThe Water TowerGunpowder MillsPowdermill LaneWaltham Abbey, Essex EN9 1BNUnited KingdomPhone: +44 1992 656 631, Fax: +44 1992 656 700e-mail: [email protected] and Middle East

Classifieds/Literature Showcase

Account Executive Paige Rogers1421 S. Sheridan Rd.Tulsa, OK 74112Phone: 918-831-9441, Fax: 918-831-9834email: [email protected]

14 Mitsubishi Power Systems Americas Inc 25

www.mpshq.com

16 New York Blower Company 27 www.nyb.com

23 Nol-Tec Systems Inc 37 www.nol-tec.com

15 Nord-Lock\Superbolt 26 www.nord-lock.com

17 Orion Instruments 29 www.orioninstruments.com

30 PennWell Webcast 54 www.power-eng.com/webcast

6 Philadelphia Gear Corporation 11

3 PIC Group Inc 5 www.picworld.com

31 POWER-GEN INTERNATIONAL 55 www.power-gen.com

24 Renewable Energy World North America 39

RenewableEnergyWorld-Events.com

21 Siemens AG 35 www.siemens.com/energy

1 Solvay Chemicals Inc C2 www.solvair.us

9 Structural Integrity Associates 17 www.structint.com/power-eng

10 Sturtevant Inc 19 www.sturtevantinc.com

5 Team Industrial Services 9 www.teamindustrialservices.com

19 Wanzek Construction Inc 32 www.wanzek.com

4 Westinghouse Electric Co 7 www.westinghousenuclear.com

Advertisers and advertising agencies assume lia-

bility for all contents (including text representation

and illustrations) of advertisements printed, and

also assume responsibility for any claims arising

therefrom made against the publisher. It is the

advertiser’s or agency’s responsibility to obtain

appropriate releases on any items or individuals

pictured in the advertisement.

27 Aggreko 47 www.coolingtowers.com

22 APEX Engineering Products 36 www.apexengineeringproducts.com

7 Bibb Engineers, Architects, Constructors 13

www.bibb-eac.com

25 Brand Energy and Infrastructure Services 43

www.beis.com

Brandenburg Industrial Service Company C4

www.brandenburg.com

32 Caterpillar Inc. 59 www.catgaspower.com

34 COAL-GEN 65 www.coal-gen.com

13 Diamond Power International 23 www.diamondpower.com

11 Dresser-Rand 22 www.dresser-rand.com/products

20 Fibrwrap 33 www.fibrwrap.com

12 Goodway Technologies Corp 22 www.goodway.com

2 Gundlach Crushers/Pennsylvania Crusher 3

www.TerraSource.com

33 Harco 61 www.harcolabs.com

26 Hitachi Power Systems Amercia Ltd 45

www.hitachipowersystems.us

35 Hobas Pipe USA C3 www.hobaspipe.com

HYTORC 49 www.torquegun.com

8 Ingersoll Rand 15 www.ingersollrandproducts.com

29 Light Engineering Inc 53 www.It-eng.com/products/find-a-

distributor

18 Magnetrol International 31 www.magnetrol.com

28 Membrana 52 www.liqui-cel.com

1306pe_72 72 6/4/13 4:05 PM

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HOBAS PIPE USA

281-821-2200

www.hobaspipe.com

What Makes HOBAS® The Standard?

Precision centrifugal casting, consistent high quality, fiberglass-reinforced, polymer mortar pipes

Responsive customer service, on-site field reps backed by extensive engineering support

Time Proven

Leak Free

Long Lasting

Corrosion Resistant

High Strength

Quick, Easy Installation

High Flow Capacity

For info. http://powereng.hotims.com RS# 35

1306pe_C3 C3 6/4/13 4:07 PM