8. usc steam turbine - engsoft power lab - engineering, …€¦ · · 2015-05-11usc steam...

Steam Turbine 8. USC Turbine 1 / 93

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8. USC Steam Turbine

SST5-6000 Steam

Turbine (Siemens)


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Advanced USC 52 4

USC Materials 83 6

USC Steam Turbine 2 1

Representative USC Steam Turbine 39 3

Reduction of CO2 Emission 64 5

USC Cycle Optimization 24 2


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Coal-fired power generation is still a fundamental part of energy supply all over the world.

Reliability, security of supply, low fuel costs, and competitive cost of electricity make a good case for coal-

fired power plants.

Requests for sustainable use of existing resources and concerns about the effect of CO2 emissions on global

warming have strengthened the focus of plant engineers and the power industry on higher efficiency of

power plants.

Efficiency has more recently been recognized as a means for reducing the emission of carbon dioxide and

its capture costs, as well as a means to reduce fuel consumption costs.

USC power plant is an option for high-efficiency and low emissions electricity generation.

USC steam conditions are characterized by 250 bar and 600C main steam and 600C reheat steam

conditions.

It is based on increased steam temperatures and pressures, beyond those traditionally employed for

subcritical plants.

Every 28C (50F) increase in throttle and reheat temperature results in approximately 1.5% improvement in

heat rate.

Besides increasing the steam parameters, optimizing the combustion process, reducing the condenser

pressure, and improving the internal efficiency of the steam turbines are some of the well known means for

raising the overall plant efficiency.

Due to the efficiency penalties associated with carbon capture and storage, such improvements are more

than ever needed to ensure a sustainable generation of electricity based on coal.

Background for the Development of USC Plants


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Improvement of Steam Turbine Efficiency

1% increase of efficiency = Fuel save $372,300/year (GE, 1995)

= Fuel save \4 billion/year (한전, 2010) (for a 500 MW unit with a capacity of 80%)

Improvement in

Mechanical Efficiency

Improvement in

Thermodynamic Efficiency

Advanced Steam Path

Technologies

USC Steam Turbine

Advanced Steam Cycle and

Materials

Reduction of

• Aerodynamic losses

• Leakage losses

Increasing of

• Main steam temperature

• Main steam pressure


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USC Steam Turbine [1/2]

GE

Increase in efficiency have been achieved largely through two kinds of advancement: (1) improving

expansion efficiency by reducing aerodynamic and leakage losses as the steam expands through the turbine;

and (2) improving the thermodynamic efficiency by increasing the temperature and pressure at which heat is

added to the power cycle.

The later improvement is the core of USC technology.


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USC Steam Turbine [2/2]

GE

The appropriate steam turbine configuration for a given USC application is largely function of the number of

reheats selected, the unit rating, the site back pressure conditions.

Specific design details will also determine the number of flows in a turbine section, the number of stages,

and the LSB length.

In particular, the site ambient conditions

and the condensing system will play a

major role in the selection of the LSB

and the number of LP section flows.

The 1.5 in.Hga would be for a direct

cooled condenser, or cooling tower in a

cold environment.

The 3.5 in.Hga would be for cooling

towers in an area with warmer

environment temperatures.


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Nomenclature Steam Conditions Net Plant

Efficiency, %

Net Plant Heat Rate

(HHV), Btu/kWh

Subcritical 2400 psig (16.5 MPa)

1050F/1050 F (565C/565C) 35 9751

Supercritical (SC) 3600 psig (24.8 MPa)

1050F/1075F (565C/585C) 38 8981

Ultrasupercritical (USC) 3600 psig (24.8 MPa)

1100F/1150 F (593C/621C) 42 8126

Advanced

Ultrasupercritical (A-USC)

5000 psig (34.5 MPa)

1292F (700C)

and above

45 7757

Classification of Fossil Plants

EPRI

Critical point of water = 3208 psia/705°F (22.09 MPa/374.14C)

Supercritical steam cycles: Operating pressure is higher than critical pressure of water. Water to steam

without boiling.

Ultra-supercritical steam cycles: Steam temperatures above 1100°F as defined by Electric Power Research

Institute (EPRI)


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Concept of USC

Critical point for water : 3208 psia/705°F (22.09 MPa/374.14C)

The surface tension property of water becomes zero at the critical point.

Therefore, there is no clear distinction between the liquid and the gaseous phase.

p

A

E

D

C

B

K

TO

TS

TK

TE

Wet steam

Water Superheated steam

o x h f g

USC

Subcritical

SC


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Characteristics of Supercritical

There is no distinction between water and steam in supercritical units


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P-h Diagram


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Parameter Units Subcritical USC

Plant size MW 600 600

Net plant efficiency % LHV 38.0 46.0

Total investment cost EU/kW 874 920

Fuel price EU/GJ, bituminous 1.6 1.6

Load factor % 85 85

Cost of electricity c/kWh

UK p/kWh

3.5

2.3

3.3

2.2

Breakdown of cost

of electricity

Fuel

Capital

O&M

c/kWh

1.5

1.3

0.7

1.2

1.4

0.7

Comparison of Cost

Source: Best Practice Brochure (DTI, 2006)


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History of USC [1/7]


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Siemens



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Te

mp

era

ture

[C

], P

ressu

re [b

ar]

0 1920 1940 1960 1980 2000 2020

700

800

500

600

300

400

100

200

0

10

20

30

40

50

60

1

10

100

1000

10000

Max O

utp

ut Tandem

Com

pound [M

W]

Th

erm

al E

ffic

ien

cy [%

]

Pressure

Thermal Efficiency

Temperature

Power Output

Steam Cycle

Simple Reheat Supercritical

Siemens



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Higher maintenance cost .

Lower operational flexibility, availability and reliability.

Control valve wear.

Thermal stress.

Solid particle erosion of turbine blades.

Much more complicated start-up process.

Probability of greater potential for turbine water induction through the main steam system compare to drum-

type subcritical units.

Higher stress corrosion cracking.

More sensitive to feedwater quality.

Experienced Problems in USC Units



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In 1957, the first USC units were put into commercial operation in USA and UK.

• AEP(American Electric Power) Philo unit 6

• 120 MW with steam flow of 675,000 lb/h

• Steam conditions: 4500 psig/1150F/1050F/1000F (double reheat)

• 395 MW Drakelow C (UK)

In 1959, Eddystone 1 (Philadelphia Electric Co.) was erected and commissioned in 1960.

• 325 MW with steam flow of 2,000,000 lb/h

• Steam conditions (initial): 5000 psig/1200F/1050F/1050F (double reheat)

• Steam conditions (later): 4700 psig/1130F/1030F/1030F (double reheat)

• Net plant efficiency: 40% (HHV, without environmental system auxiliary power)

• Net plant heat rate: 8534 Btu/kWh

• Throttle steam conditions were changed because of serious mechanical and metallurgical problems.

• Most of the problems were due to the use of austenitic steels for thick section components operating at

high temperatures.


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• It is well known that austenitic steels have low thermal conductivity and high thermal expansion resulting

in high thermal stresses and fatigue cracking.

• These problems and initial low availability of many USC power plants temporarily dampened utilities in

building USC power plants and consequently most utilities reverted back to subcritical power plants.

• Additionally, USC plants have another problems compared to subcritical units, such as higher

maintenance costs, lower operational flexibility, lower reliability of steam turbines.

• Many problems were related to the steam turbine control valve wear and tear, to the turbine blade

thermal stress, to the solid particle erosion of blades and valves, and to more complicated start-up

procedures.

• USC units are also more sensitive to feedwater quality. Therefore, full-flow condensate polishing is

required to protect the turbine from stress corrosion cracking.

• After that, through more than 45 years of practices, USC technologies have been unceasingly

developed and gradually perfected.

• Operational experience worldwide has brought the evidence, that present availability of USC power

plants is equal or even higher than those of subcritical ones.



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A-USC study (ongoing project by DOE)

• 792 MW, 36.2 MPa/735.5C/760C (5250 psig/1356F/1400F) (single reheat)

• Final feedwater temperature: 332.8C (631F)

• Estimated net plant heat rate: 6293.1 Btu/kWh (6633 kJ/kWh)

• A net plant efficiency of 44.6 to 45.6% is possible with boiler fuel efficiency of 89 to 90% and auxiliary

power between 6.5 to 7.5% of gross generation.

• For 700C plants, it has been reported that double reheat has an efficiency improvement of only 0.7%

(HHV). The double reheat cycle has provided 1.5 to 2.0% of efficiency gain above single reheat at

538C (1000F) throttle conditions.

• The cost/benefit for double reheat will need more evaluation and the first A-USC plant will more likely be

single reheat and employ double reheat when justified later.



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Heat Rate Improvement by USC

1000 1100 1200

Pla

nt N

et H

ea

t R

ate

Im

pro

ve

me

nt,

%

8

7

6

5

4

3

2

1

0

2.8 %

2.4 %

2400 psig/1000F/1000F

versus

4500 psig/1100F/1100F

2400 psig (165 bar)

Sub-Critical

USC 2900 psig (200 bar)

3650 psig (250 bar)

4350 psig (300 bar)

5800 psig (400 bar) 5050 psig (350 bar)

Double Reheat vs. Single Reheat:

Heat Rate Improvement = 1.6%

Temperature, F

Comparison

2.8% + 2.4% + 1.6% = 6.8%

Siemens


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Efficiency Improvement by USC

7% cycle efficiency improvement by steam condition

from 160bar / 540C / 540C

to 290bar / 600C / 620C


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Prediction of Future for Coal Power Plants

20

40

60

80

100

0

2000 2005 2010 2020 2030 2040 2050

Small Coal Unit

Large Coal Unit USC SC

IGCC

IGCC + Fuel Cell


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EPRI

Current Situation of Coal Plants in US

The construction of new coal fired power plants has reduced greatly in US.

• Coal fired power plant being retired in response to tighter environmental regulations.

While market for new coal power not favorable now, the past few years have shown how volatile the outlook

for power generation can be

• Is it wise to put all eggs in the natural gas basket?

• Gas price is volatile: if all new generation is natural gas fired, electricity prices will fluctuate

correspondingly.

• Gas is a fossil fuel and emits CO2: evenly CCS will be applied to NGCC.

Advanced coal fired USC technology will help stabilize electricity prices and keep them affordable, but if it is

to be available in 2025 needed to work on it today.

Fuel diversity continues to have value in stabilizing cost of electricity.


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Advantages Considerations

• Increase the plant efficiency significantly

• Reduce fuel consumption for a given output

• Reduce all pollutant and waste, including CO2

• Higher investment cost

• Reliability

• Operational flexibility

USC Technologies

1) Improvement of power density

• Increased number of stages

• Decreased inner ring diameter

• Optimized stage reaction levels

• Optimized stage energy level

2) Improvement of mechanical design

• Advanced vortex blades

• Advanced sealing

• Integral cover bucket (ICB)

• Full arc, hook diaphragm first stage

• Advanced cooling scheme

3) Improved HP/IP/LP shell design

4) Advanced LP design with 45 LSB


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Advanced USC 4

USC Materials 6

USC Steam Turbine 1

Representative USC Steam Turbine 3

Reduction of CO2 Emission 5

USC Cycle Optimization 2


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Cycle Optimization

① Reduction of condenser pressure larger heat transfer surfaces, and inclusion of an advanced LP exhaust

hood

② Reduction of boiler flue gas reduction of fan power

③ Reduction of boiler pressure losses and leakages water treatment for water/steam side;

slagging/fouling/erosion reduction for flue gas side

④ Minimization of combustion air excess

⑤ Minimization of thermal losses

⑥ Improvement of boiler and turbine components technical design advanced steam path technologies for

turbine side

⑦ Optimization of main steam parameters advanced steam cycle

⑧ Application of single or double reheat advanced steam cycle

⑨ Optimization of feedwater temperature optimized regenerative cycle


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Siemens

Efficiency Improvement in PC-Fired Plant

46

45

44

43

42

41

43

42

41

40

39

% %

1.15

1.25

120C

130C

300 bar/600C

250 bar/540C

Single reheat

Double reheat

1.9 in.Hga

0.88 in.Hga

Excess Air Discharge

Flue Gas

Temperature

Main Steam

Condition

Reheat Back

Pressure

Pla

nt N

et E

ffic

ien

cy B

ase

d o

n L

HV

Pla

nt N

et E

ffic

ien

cy B

ase

d o

n H

HV

USC


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Economic Efficiency Improvement

How to best apply the capital funding available on a power plant project is a critical question for the plant

designer.

The cost basis of technological improvements must be known to make an economic evaluation in today’s

competitive marketplace.

One open literature investigated that the ranking of several technology improvement steps for better plant

efficiency. From least cost to highest cost per efficiency improvement, million US$ / % net LHV efficiency,

these were.

1) Reducing condenser back pressure, 4.6

2) Increasing to 8th extraction point feedwater heater, raising feedwater temperature, 5.7

3) Raising main steam temperature and reheat steam temperature, 12.3

4) Raising main steam temperature, 12.7

5) Using separate BFPT instead of main turbine driven pump, 14.2

6) Raising main steam pressure, 39.1

7) Changing from single to double reheat, 56.7

8) Using separate BFPT condenser, 60.7


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1) Main Steam Temperature

Pressure, psia

Ava

ilab

le E

ne

rgy,

Btu

/lb

0

1000F

1100F

1200F

1300F

1400F

1000 2000 3000 4000 5000 6000 7000 8000

850

900

750

800

650

700

550

500

500

In the evaluation of steam conditions, the potential cycle efficiency gain by elevating steam pressures and

temperatures must be considered.

Most of the efficiency increase results from increased temperature, not pressure.

Therefore, temperature is the more important factor regarding cycle efficiency than pressure.


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Selection of main steam pressure is of secondary importance in terms of the cycle efficiency.

This is because higher main steam pressure results in higher component costs. Thus, the optimum value

should be found.

The thick pressure parts will require a very limited rate of load change and longer start up times. Therefore,

designers should optimize the operating pressure with the design temperature and select materials having

optimum properties and cost.

Starting with the traditional 2400 psig/1000F single reheat cycle, great improvements in power plant

performance can be achieved by raising inlet steam conditions to levels up to 310 bar (4500 psig) and

temperatures to levels in excess of 600C (1112F).

In a reheat cycle, increasing the main steam pressure will improve the cycle efficiency and this is the

incentive for using supercritical steam conditions.

However, the thermodynamic benefit of increased main steam pressure at a given temperature is subject to

diminishing returns because the significant reduction in volumetric flow at these conditions leads to shorter

and wider turbine blade that is subject to higher passage boundary losses and increased steam path

leakage.

These blade losses act to offset the thermodynamic benefits of elevated steam conditions with increased

main steam pressure.

It is generally accepted that increasing the main steam pressure above 300 bar with steam temperatures of

600C/620C does not offer any further economic benefits.

2) Main Steam Pressure


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3) Reheat Pressure

Normally, the cold reheater pressure is a quarter of the main steam pressure. Therefore, the selection of the

cold reheat pressure is an integral part of any power plant design. However, it becomes even more important

for plants with USC steam conditions.

The improvement resulting from the use of a HARP can be about 0.5%.

However, economic considerations of the boiler design without a HARP tend to favor a lower reheater

pressure at the expense of a slight decrease in cycle performance. Therefore, the resulting net heat rate gain

is usually larger, approaching 0.6~0.7%.

The use of a HARP results in a lower optimal reheater pressure and a higher optimal feedwater temperature.

Both of these considerations significantly impact the design and cost of the boiler.

As a result, careful optimization need to be done, in considering the use of a HARP, to ensure an

economically optimal cycle selection is made.

For double reheat units without HARP, the best performance would be achieved with the first reheat pressure

of approximately 1450 psi(100 bar).

However, economic considerations associated with the boiler and piping systems would typically favor

reducing this to a lower level.

The typical outcome is that the first reheat pressure is chosen below the thermodynamic optimum while the

second reheat pressure is generally selected slightly above to reduce the LP inlet steam temperature.


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Double Reheat Cycle with HARP

3) Reheat Pressure


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Four-Casing, Four-Flow, Double-Reheat Steam Turbine

HP RH1 RH2

3) Reheat Pressure


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4) LP Inlet Temperature

The use of advanced reheat steam conditions strongly affects the inlet temperature to the LP turbine section.

An increase in hot reheat temperature translates into an almost equal increase in crossover temperature for

a given crossover pressure.

However, the maximum allowable LP inlet temperature is limited by materials associated with the rotor,

crossover, and hood stationary components. Of these, the rotor material temperature limits are usually

reached first.

In addition, the selection of hot reheat temperature (and corresponding effect on LP inlet temperature)

impacts the amount of moisture at the LSB which factors into stress corrosion cracking considerations.

Once the reheat steam conditions are established, then the LP steam conditions can be determined.

If the resulting crossover temperature is too high, the energy ratio between the IP and LP can be changed to

lower this temperature.

Increasing the energy on the IP section will lower the crossover temperature, but it will also impact the cycle

efficiency, increase the number of IP stages, or the loading of the IP stages, increase the height of the final

IP bucket, increase the size of the crossover, or increase the pressure drop through the crossover.

LP inlet temperature can be adjusted by both reheater pressure and crossover pressure.

To lower the crossover temperature, the reheater pressure has to be increased or the crossover pressure

has to be decreased.

Crossover temperature is increased when a HARP is employed because it choose lower reheater pressure

to increase the thermal efficiency of plants.


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5) Regenerative Rankine Cycle

The Rankine cycle can be used with a feedwater heater to heat the high pressure subcooled water at the

pump exit to the saturation temperature.

The cycle efficiency can be increased, if the feedwater is heated by extracted steam from turbine. In this

case the temperature of the feedwater becomes higher. This cycle is called as a regenerative cycle.

Heating of the feedwater is accomplished by using small amounts of extracted steam having high enthalpy at

various points in the expansion through the turbine.

T

s

condenser

pump1

Boiler

G Turbine

FWH

pump2

Boiler (1)

Feedwater heater (m)

Condenser (1-m)


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The heat input in the boiler decreases as the final feedwater temperature increases and the heat rejected in

the condenser getting smaller as the feedwater is heated higher using the extracted steam.

The more heaters are used, the higher thermal efficiency.

If a large number of heaters is used, the process of feedwater heating is more reversible.

For this reason, the regenerative cycle improves the thermal efficiency of the power plant.

The feedwater heater arrangement has to be designed to obtain the best heat rate for a given set of USC

steam conditions.

In general, the selection of higher steam conditions will result in additional feedwater heaters and a higher

final feedwater temperature.

The higher final feedwater temperature will have an impact on the boiler cost.

This then requires a system level optimization to determine the best economical solution for the increase in

final feedwater temperature.

In many cases, the selection of a heater above reheat point (HARP) is recommended.

Employment of a HARP has a strong influence on the design of both turbine and boiler.

The use of separate de-superheater ahead of the top heater for unit with a HARP can results in additional

performance gain.



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In order to maximize the efficiency with USC steam conditions, a HARP is employed for a optimal higher

feedwater temperature.

Additionally, HARP impact the cost of the boiler significantly.

Cycle No. of Feedwater Heaters HARP Heat Rate Benefit

Single Reheat

(4500 psig, 1100F/ 1100

F)

7

8

8

9

No

No

Yes

Yes

Base Case

+0.2%

+0.6%

+0.7%

Double Reheat

(4500 psig, 1100F/ 1100

F/1100F)

8

9

9

10

No

No

Yes

Yes

Base Case

+0.3%

+0.2%

+0.5%

[ Heat rate impact of alternative feedwater heater configurations ]



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SSR: Steam Seal Receiver, SPE: Steam Packing Exhaust

HARP: Heater Above Reheat Point

Single Reheat Cycle with HARP



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① Final feedwater temperature = 327C

② First reheat pressure = 9.5 MPa

③ Second reheat pressure = 3.5 MPa

④ Crossover pressure = 1.0 MPa

31.0 MPa / 600 / 610 /610 C

Cycle Optimization - Example

Siemens


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Advanced USC 4

USC Materials 6

USC Steam Turbine 1





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USC Steam Turbine – Siemens [1/5]

Key Technical Features

Model SST5-6000

Gross power output 813 MW

Net plant efficiency (based on

cooling tower) ~45.6% (@ design point)

Main steam conditions 280 bar/600C/610C

LP turbine - LSB 4 Flow - 45

Feedwater preheating 9-stages

Final feedwater temperature 308C

Specific CO2 emission Well below 800 g/kWh


Model SST-6000




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Mixed steam Cooling

steam Outer

casing

inner

casing

Stage

balance

piston



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The basic design characteristics of HP turbine is the barrel type outer casing design and has an inner casing.

This design can enable 300 bar and 600C.

This rotation-symmetric design has minimum deformation during steady-state and transient operation and a

consequence minimum clearances i.e. minimum leakage losses are achieved.

The barrel type outer casing has an axial split casing which can handle highest pressure loadings by

adopting the wall thickness. This gives an optimal thermal deformation behavior because there is no

horizontal flange. The benefit is small radial clearances between inner casing and blades, that means best

turbine efficiency.

Advanced sealing technologies such as brush seals and abradable coatings reduce steam leakages even

further.

USC steam conditions require the use of thick-walled components.

In order to remove this restriction, an internal bypass cooling system has been developed.

Basically, a small amount of cooling steam passes through radial bores into the small annulus between the

inner and outer HP casing.

The cooling steam is lead through the inner casing towards the balance piston.

Thus, the surface temperature is reduced, creep stresses are reduced, and customers’ lifetime requirements

are met.

The internal bypass cooling also effectively protects the inner surface of the outer casing, which would be

exposed to main steam temperature without the internal bypass cooling.



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As a consequence, it was possible to reduce the wall-thickness of the outer casing and thus enable

faster start-up of the casing.

An improved starting performance is the main customer benefit of this innovative concept.

3DV technology (3-dimensional design with variable reaction levels) is applied for HP and IP blades.

The IP turbine is designed to take reheat steam

temperature of 620C. Thus, the first stage blades are

made of nickel alloy.

The high steam temperature can be handled by

reducing the rotor surface temperature by a cooling

principle named vortex cooling.

This cooling principle enables a temperature decrease

due to the reduction of relative steam velocity at the

rotor surface.

The double flow, double casing turbine has a full arc

admission. This first stage has zero flow losses and

gives the best transition from a radial flow in the inlet

ring to an axial flow in the double flow blade path.



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The LP turbine consists of a double flow with a horizontal split casing.

The push rod permits parallel axial thermal expansion of LP rotor and inner casing by directly coupling the IP

outer casing with the LP inner casing.

This reduces clearances between rotor and casing and improves the efficiency.

Free-standing 45 LSBs made by steel provide an annular area of 12.5 m2 per flow. Titanium LSB will be

applied in the near future.

Frequency control through condensate throttling.



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USC Steam Turbine – GE [1/5]



Net plant efficiency 48.7% (@ design point)


(3626 psia/1112F/1130F)


Arrangement of rotor shaft Cross-compound



Net plant efficiency ?


(3770 psia/1150F/1180F)


Arrangement of rotor shaft Tandem-compound


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Main steam enters the section through two pipes (top

and bottom).

A heater above reheat point extraction is taken from

the lower half.

HP turbine eliminated the partial admission, control

stage, and nozzle box.

Older steam turbine designs utilized a control valve to

control pressure and load during transient conditions.

The mechanical design requirements of this stage,

having to withstand partial arc stimulus, often result in a

very large and inefficient 1st stage design than can be

5-10% lower efficiency than the other HP stages.

1) HP Section Design

Therefore, GE chose to implement a full arc 1st stage design, which is much higher reaction and lower

aspect ratio to a traditional control stage.

This enables the first stage design to rival the efficiency of other stages.



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To allow this, however, changes need to be made to allow the turbine quickly and efficiently respond to load

swings.

Therefore, GE will utilize an overload valve that will bypass the first stage and allow additional flow/load

response.

An overload admission was added for frequency control and capacity margin.

Elimination of the nozzle box required that two inner shells be used.

In this arrangement, the inlet #1 inner casing is subject to adjacent stage steam conditions on its inner

surfaces and a downstream stage’s steam pressure on its outer surface.

The buckets of the first four stages are made of nickel-based material due to the high temperature creep

requirements. The remaining buckets are conventional 12Cr material.

All 10 stages will utilize integral cover buckets with advanced tip seals.

The wheel spaces of the first two stages are cooled using external cooling steam.

A combination of brush, variable clearance, and conventional shaft seals are used in the HP section.

The corresponding outer casing inner surface is subjected to steam conditions at the same downstream

steam pressure.

Full admission design alleviated the mechanical challenges associated with partial admission design and the

control stage.

1) HP Section Design – 1st Stage



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2) IP Section Design

The IP section is designed in a double flow configuration.

Two feedwater heater extractions are taken from the lower half.

Single casing construction is used.

The number of stages is 8.

The buckets of the first three stages are made of nickel-based material due to the high temperature creep

requirements. The remaining buckets are conventional 12Cr material.

All 8 stages will utilize integral cover buckets with advanced tip seals.

The wheel spaces of the first two stages are cooled using cooling steam, from HP section.

A combination of variable clearance and conventional shaft seals are used in the HP section.



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3) LP Turbine Design

The LP turbine design for the 1000 MW

consists of 5 stages with four extractions.

Last stages utilize 45 titanium blades.

In addition, LSB employs advanced curved

axial entry dovetails.

The first two LP stages utilize high reaction

stage design for optimal efficiency.

Advanced brush seals are utilized to reduce

leakage losses.



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700C Steam Turbine Development [ALSTOM]

Welding Balance Piston

USC Steam Turbine – Alstom


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USC Steam Turbine - Doosan


Output @ Max Guarantee Rating 1000 MW

Output @ VWO 1100 MW

Net plant efficiency 49% (estimated value)


LSB 4 Flow - 45

Cycle Single reheat regenerative

Bearings

LP Casing

LP Inner Casing

Reheat Stop and

Intercept Valves Double Shells Packing

Head

Packing

Head

Wheels and

Diaphragms


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Advanced USC 4

USC Materials 6

USC Steam Turbine 1





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Parameters Subcritical Supercritical 1100F USC 1290F A-USC

Perfor-

mance

Main steam, F/psia 1005/2600 1080/3800 1120/4000 1290/5100

Net efficiency, % (HHV) 36.5 38.5 39.2 43.4

Net heat rate, Btu/kWh (HHV) 9370 8880 8720 7880

Coal flow, lb/hr 840,600 797,000 782,700 707,000

Flue gas, ACFM(actual ft3/min) 2,107,000 2,016,000 2,107,000 2,107,000

Make-up water, gpm 4,260 3,750 3,650 3,300

NOx & SOx, lb/MWh 0.280 0.266 0.261 0.236

CO2, lb/MWh from plant 1980 1880 1840 1660

Cost

Fuel cost, $/MBtu (HHV) 1.80 1.80 1.80 1.80

TPC, $/kW 1,780 1,800 1,840 1,990

Capital, $/MWh 28.9 29.3 29.9 32.3

Fixed O&M, $/kW-yr 48.5 49.1 50.3 54.3

Var. O&M, $/MWh (2) 1.57 1.47 1.43 1.33

Fuel, $/MWh (1) 16.9 16.0 15.7 14.2

LCOE, $/MWh 53.9 53.3 53.8 55.1

Dispatch cost, $/MWh (=(1)+(2)) 18.5 17.5 17.1 15.5

CO2 adder, $/MWh ($25/ton of CO2) 24.8 23.5 23.0 20.8

LCOE, $/MWh 78.7 76.8 76.8 75.9

Dispatch cost, $/MWh (=(1)+(2)) 43.2 41.0 40.1 36.3

Comparison of Parameters


HIoPE

A-USC Steam Conditions

Steam Conditions Remark

EPRI 5100 psia/1290F/1330F (347 bar/700C/721C)

Net plant efficiency = 43.4% (HHV)

• Boiler efficiency = 87.2%

• HP/IP/LP effi. = 90/94.2/88.6%

US. DOE 5015 psia/1350F/1400F (341 bar/732C/760C) Materials program objective

EU 5500 psia/1290F/1330F (375 bar/700C/721C) Net plant efficiency = 52-55% (LHV)

Some abbreviations and its definition

TPC: Total Plant Cost.

LCOE: Levelized Cost of Electricity.

Fixed O&M: personnel and insurance costs.

Variable O&M: cost depending upon the operation regime of the plant. Included items are:

• Inspection and overhauls, including labor, parts, and rentals

• Water treatment expenses

• Catalyst replacement

• Major overhaul expences

• Air filter replacements


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A-USC (Advanced Ultra Supercritical) means a coal fired power plant design with the inlet steam

temperature of 700C to 760C (1292F to 1400F).

The higher the inlet steam temperature, the higher the efficiency of a plant.

The higher the efficiency of a plant, the less fuel consumption, and fewer emission are produced during

electricity generation.

Therefore, the purposes of A-USC plants are reducing the emission of CO2 and its capture cost, and fuel

consumption by increasing the efficiency of power plants.

When the heat is supplied at 760C, the Carnot cycle efficiency is 69.9%, while the expected A-USC net

plant efficiency is 52.7% (6825 kJ/kWh, or 6475 Btu/kWh).

USC uses ferritic and stainless steels, while A-USC requires nickel alloy materials.

The costs of the higher priced nickel alloys must be balanced with the savings in less fuel consumption,

lower weight and size of equipment, and cost avoidance for emission allowance requirements.

TPC(Total Plant Cost) for 1290F A-USC is 11% higher than for SC unit, but potential to halve the difference

because the cost of high temperature materials is getting lower.

A-USC plants have the potential for lower cost of electricity especially when combined with the requirements

to capture carbon for sequestration (CCS).

The plant production costs per megawatt-hour are the lowest for A-USC w/CCS based on plant economic

studies for coal firing. Combining CCS with A-USC plants will provide lower cost of electricity generation with

90% CO2 capture.

Currently, A-USC studies have been focused on 50Hz machines. This is because the rotating components of

60Hz machines require reduced steam temperatures by 40F to meet strength requirements.

Generals


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Selection of Throttle Pressure

Throttle pressure for the Rankine cycle is fundamental to the optimum amount of available energy of the

working fluid at the specified operating throttle temperature. The optimum throttle pressure increases with

throttle temperature.

Throttle pressure for the desired throttle temperature of 700 to 760C will most feasible in the range of 5000

to 5500 psi.

Considering a single reheat cycle, the optimum available energy peaks at about 2500 psia for 1000F, about

4000 psia for 1200F, and at about 5000 psia for 1400F.

Because higher pressure results in higher component costs, the optimum available energy should be

investigated.

Higher steam pressure can help to reduce the flow path pipe size delivering the energy flow.

The more compact plant equipment will help with cost savings as long as pressure vessel thickness and

material costs are at the optimum.

Due to concerns that very thick parts will require a very limited rate of load change and longer start up times,

the throttle pressure should be determined with optimum properties and cost.

Temperature is the more important factor regarding cycle efficiency.

Selection of pressure is of secondary importance in terms of efficiency.

Setting the HP throttle pressure, the IP inlet pressure and the LP exhaust pressure is important for the

optimization and meeting acceptable operating conditions.


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Double Reheat Cycle

The double reheat cycle has normally been considered to provide 1.5% to 2.0% of efficiency above single

reheat for throttle temperature of 538C to 593C (1000F to 1100F).

It has been reported that the double reheat cycle would only provide 0.7% advantage above single reheat

turbine with inlet conditions of 35 MPa/680C/700C (5075 psig /1256F/1292F).

High temperature of the second reheat steam requires nickel alloy for its larger diameter piping. Thus, piping

cost should be considered.

Operation of a double reheat cycle was considered more difficult because of controlling the differential

between the HP, IP 1 and IP 2 steam temperatures.

The first A-USC plants will more likely be single reheat and double reheat may be adopted later.

Double reheat technically feasible, but not economic.

• Long expensive piping between the boiler and steam turbine.

• Additional boiler heat transfer surface area.

• Additional turbine complexity.


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Turbine Cycle

The capacity of the steam turbine under studying is 750 MW.

The steam turbine throttle conditions are 35 MPa/732C/760C (5000 psig /1350F/1400F) with 2 in.Hga

condenser pressure.

An additional new requirement of an A-USC boiler is to deliver cooling steam from a source such as the

primary superheater at 1.5% of main steam flow rate to the HP outer casing.

1.5% cold reheat steam is retained at the turbine for IP turbine outer casing cooling.

Feedwater temperature to the economizer has ranged from 630F to 649F at MCR. Reducing the

economizer gas outlet temperature is a little more difficult because of the higher final feedwater temperature

of A-USC.

A-USC steam turbine section efficiencies are expected to lie in the following range depending on offered by

various vendors; HP: 89.2~93.3%, IP: 90.5~96.6%, LP: 90.6~95.8%.

The net plant efficiency is in the range 46~48% based on HHV.

CCS will affect net plant efficiency because total auxiliary power for CCS will be about 20.5% of gross power

generation.

Oxy-combustion A-USC plant efficiency with Ohio coal is estimated to be 38.1% (HHV) with 90% capture of

carbon dioxide.


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Steam Turbine

Major characteristics

• HP turbine may have two stage because of limited use of nickel alloy

• Start up time longer because of higher temperature, but frequency control not expected to be affected

• BFW extractions are similar, but final feedwater temperature will become higher

Same availability

• A-USC steam turbines should have same availability as conventional turbines.


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Time Schedule of A-USC

EPRI


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EPRI

PCC: post-combustion capture

Oxy: oxy-combustion

Time Schedule of A-USC


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AD 700 Cycle

AD 700 is an advanced 700C PF power plant has being developed in European Union.

Steam conditions: 375 bar/700C/ 720C

Plant efficiency: 52-55%

Fuel saving and CO2 emission reduction of up to 15% compared with the best available technology of today.

Construction and commissioning will be finished in 2013.


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Time Schedule of AD 700 Cycle


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Advanced USC 4

USC Materials 6

USC Steam Turbine 1





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Clean and cheap power generation is of prime importance to cope with the challenges imposed by an

increasing energy demand throughout the world.

In recent years, costs associated with CO2 emissions have attracted more attention because of global

warming.

Carbon capture and storage (CCS) and capture ready power plant designs are becoming increasingly

important for the evaluation of investments into new power plants and in addition retrofit solutions for the

existing power plants are required.

Efficiency improvement is a means for reducing emission of CO2, the costs of carbon capture, water use,

particulates, sulfur dioxides (SO2) and nitrogen oxides (NOx) emissions, and fuel consumption.

As coal is more abundant in many parts of the world, coal price is more stable than natural gas price.

However, greater CO2 emissions increase the need for more efficient coal-fired power plants.

USC steam power plants meet notably the requirements for high efficiency to reduce both fuel costs and

emissions as well as for a reliable supply of electric energy at low cost.

Recent developments in steam turbine technologies and high-temperature materials allowed for significant

efficiency gains.

Due to CO2 emission limits and corresponding penalties, the conventional coal-fired power plant with the

efficiency lower than 40% become less cost-effective.

NETL and EPRI studies show that current CCS technologies have CO2 removal costs of $50 to 70/ton.

Background for USC Power Plants


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CO2 Emission vs. Plant Efficiency

CO

2 E

mis

sio

n, g

/kW

h

800

600

1200

200

0

400

Net Plant Efficiency, % (LHV)

36 48 28 32 40 44 52 56

1000


HIoPE

CO2 Emission vs. Net Plant Efficiency

Net Plant Efficiency, %

CO

2 E

mis

sio

ns, to

n/M

Wh

0.90

37

CO

2 R

ed

uction

, %

38 39 40 41 42 43 44 45 46 47 48 49 50

0.85

0.80

0.75

0.70

0.65

0.60

CO2 emissions, ton/MWh Percent CO2 reduction from

subcritical PC plant

Ultrasupercritical

PC plant range

Subcritical

PC plant

0

5

10

15

20

25

30


HIoPE

CO2 Emission vs. Plant Efficiency

The need of further reduction of environmental emissions from coal combustion is driving growing interest in

high-efficiency and low-emissions coal fired power plants.

Every 28C (50F) increase in throttle and reheat temperature results in approximately 1.5% improvement in

heat rate.

Every 1% improvement in plant efficiency results in approximately 2.5% reduction in CO2 emission.

An increase in plant efficiency from 30% to 50% reduce CO2 emissions about 40%.

A-USC plants having net plant efficiency of 45%, without CCS(Carbon Capture and Sequestration), will

produce about 22% less CO2 than the average subcritical plants that include the majority of units currently in

service and operating at about 35% net plant efficiency.

Combining CCs with A-USC plants will provide lower cost of electricity generation with 90% carbon capture.

A-USC will lower the CO2 per kWh, thus reducing the size of the CCS equipment.

Oxy-combustion CCS plant that achieve 90% carbon capture use about 20.5% auxiliary power which

includes the compression purification unit (CPU), additional cooling tower, air separation unit (ASU), and

polishing scrubber.

The efficiency penalty associated with CO2 capture based on Siemens advanced process is 9.2%.


HIoPE

1100 USC

Net P

lan

t E

ffic

ien

cy,

% (

HH

V)

25

35

40

45

30

1100 USC

w/PCC

1300 USC

w/PCC

1300 USC

w/PCC (1)

1300 USC

w/PCC (2)

1400 USC

w/PCC (3)

(1) Back-end heat recovery (2) Double reheat

(3) 1350F with back-end heat recovery and double reheat

Efficiency Gain with CCS Incorporated

1100F class USC loses efficiency of 7.7% when CCS is incorporated.

By going to A-USC conditions of 1300-1400F, plus select other improvements, this loss can be more than

recovered.

Net efficiency improvements will be enhanced by CCS improvements.

EPRI


HIoPE

Lignite: 980~1,230

Hard coal: 790~1,080

Oil: 890

NG: 640

NG Comb. cycle

Unit: g CO2/kWh

410~430

Solar 80~160

Nuclear: 16~23

Wind: 8~16

Hydro power: 4~13

Electricity generation with CCS

CO2 Emissions from Different Power Plants

The efficiency penalty associated with CO2 capture:

• Rankine cycle: 9.2% (based on Siemens advanced process)

• Combined cycle: 8% (based on GE 9FB.03 unit with a 3-pressure HRSG)


HIoPE

There are three major technologies for CCS for industrial and power plants applications.

• Post-combustion separates CO2 from the flue gases produced by combustion of a fuel in air.

• Oxy-fuel combustion uses oxygen instead of air for combustion, producing a flue gases that contains

mainly H2O and CO2. Therefore, CO2 is easily separated by condensing the water vapor.

• Pre-combustion technology processes the primary fuel in a reactor to produce separate stream of CO2 for

storage and H2, which is used as a fuel.

CO2 Capture Technologies

Post-combustion capture

• chemical absorption process

• gas-fired power plant in Malaysia

• constructed by MHI

Pre-combustion capture • physical solvent process

• coal gasification plant in US


HIoPE

CO2

Separation Power & Heat

Gasification Reformer +CO2 Sep. Power & Heat

Power & Heat

Air Separation

Process + CO2 Sep.

Post-

combustion

Pre-

combustion

Oxy-

combustion

Industrial

processes

Coal

Gas

Biomass

Coal

Biomass

Coal

Gas

Biomass

Coal

Gas

Biomass

Air

Air/O2

Steam CO2

N2,O2

N2, O2

CO2

CO2

N2 O2

Gas, Oil

Air/O2

Air

Air

Raw material Gas, Ammonia, Steel

H2

CO2

CO2 Compression

& Dehydration

CO2 Capture Process and Systems


HIoPE

De

NO

x

FG

D

EP

CO

2

Cap

ture

Flu

e G

as

Coo

ling

Chim

ne

y

Continuous

Emission

Monitoring

System

Remove

85-90% of

NOx

Remove

99.7% of

Fly Ash

Remove

90-95% of

SO2

Remove

90% of

CO2

Post-Combustion Capture Technology [1/3]


HIoPE



HIoPE

The most common method for separating CO2 from a gas stream in use today is the chemical absorption

using alkaline solvents.

The flue gas passes through an aqueous alkaline solvent, and since CO2 is acidic it is bound to the solvent.

The absorption process takes place in the absorption column.

The flue gas enters at the bottom of the absorber, while the solvent is pumped to the top of the absorber.

After the reaction and CO2 absorption, the rich- CO2 solvent drops to the bottom of the absorber and then it is

pumped to the separation unit (CO2 stripper).

In CO2 stripper the rich-CO2 solvent is heated up depending on the solvent type to 100-140C.

This reverses the absorption process and releases most of the CO2 in a pure stream for compression and

transport. The lean- CO2 solvent is transported back to the absorber for reuse.

A variety of solvents could be used in the absorption/regeneration process and each has its advantages and

disadvantages.

Choosing the right solvent is important to reduce the energy penalty of the capture process.

The most used solvent for CO2 capture is monoethanolamine.

Aqueous ammonia is used as well in capturing CO2 from flue gases.



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Oxy-Fuel Combustion Capture Technology [1/2]


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In oxy-fuel combustion capture technology nearly pure oxygen is used for combustion instead of air.

Therefore, combustion products are mainly CO2 and H2O.

If fuel is burnt in pure oxygen, the flame temperature is exceedingly high. Therefore, CO2 and /or H2O-rich

flue gas is recirculated to the combustor to moderate the temperature.

The steam can easily be removed by condensation, leaving a rich- CO2 stream ready for compression and

storage.

Oxygen is usually produced in cryogenic air separation unit which is the major demanding component in the

process.

Oxy-Fuel Combustion Capture Technology [2/2]


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Pre-Combustion Capture Technology

The pre-combustion technology refers to removing of the carbon from the fuel before combustion.

Pre-combustion capture involves reacting fuel with oxygen or air and/or steam to give mainly syngas

composed of carbon monoxide and hydrogen.

The hydrogen can then be used directly as a fuel in the gas turbine.

Burning hydrogen emits no CO2 and primary

exhaust gas from hydrogen combustion is

water.

Both pre- and post-combustion technologies

are available at a significant drop in

performance.


HIoPE

Carbon Capture Ready Power Plants [1/4]

A power plant in the capture ready design will be able to integrate the CO2 capture unit when the necessary

regulatory or economic drivers are in place.

In the EU, a capture ready assessment is mandatory for all new fossil power plants 300 MW, in other

regions capture ready programs are already implemented or still under discussion.

The aim of building power plants that are capture ready is to reduce the risk of space and connections.

In the capture ready assessment the following topics have to be addressed.

• Evaluation of available CO2 transportation and accessible CO2 storage options.

• Reservation of sufficient area on the site for the later retrofit of the CO2 capture unit including CO2

compression and all plant integration measures.

• Assessment of the economic and technical aspects for the later retrofit and integration of the CO2

capture unit.

The capture process consumes LP steam for solvent regeneration and electrical energy for the solvent

pumps and the CO2 compressors.

Cooling water is needed as well.

The mass and energy flow rates at the interfaces depend on the capture process.

Optimizing the heat integration between the power plant and the CO2 capture unit including CO2

compression will be a decisive factor for the competitiveness of a steam power plant with CO2 capture.

Siemens


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Four Main Topics should be Considered

1) Water supply and cooling tower

• These systems need to be adapted.

• Later capacity extensions should be considered in civil and in the plant layout from the beginning.

2) Auxiliary power consumption

• The electrical auxiliary load will be doubled after retrofit of the capture unit, mainly caused by the CO2

compression.

• Sufficient space, additional auxiliary transformers, switchyard and cable routes need to be considered.

3) Steam extraction

• A significant amount of the available LP steam (approx. 40%) needs to be extracted from the steam

turbine and has to be supplied to the capture unit for solvent regeneration. (2.7 GJ/ton CO2 captured,

approximately 40% of LP steam)

• Avoiding thermodynamic inefficiencies associated with throttling at full and partial load as well as keeping

the capital costs low are the main challenges.

• In addition, the different solvents and capture processes under competition vary in demand and properties

of LP steam.

4) Flue gas path

• Additional space need to be reserved for the connection of the flue gas duct with the capture unit (T-

Branch), for the installation of the additional flue gas fan and for the adaption of the FGD unit.



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Capture Ready Requirements [Siemens]

Steam turbine building sufficient space/foundation for

• Modification of turbines

• Steam and condensate pipes

• Installation of heat exchangers

Steam turbines • Extraction of approximately 40% of

LP crossover steam

• Options for modification of turbines

expand on operation modes (part

load, full load capability without

CO2 capture other plant and site

conditions)

Electrical auxiliary load sufficient space for

• Additional auxiliary transformer(s)

• Switchyard

• Cable routes

Cooling system sufficient space for

• Additional circulation pumps

• Service water system

• Sufficient cooling capacity of

cooling tower

Condensate system sufficient space for

• Heat exchangers for low grade

heat utilization

• Additional piping routes with

supporting structure/racks

Raw water & cooling water

supply / Waste water

treatment • Sufficient space for enlargement

• Secure water utilization rights

FGD • Either consider capacity

extension in column

design

• or provide space for

enlarged FGD unit

Air heating Optional: space for

installation of heat

exchanger(s) for lowest

grade heat utilization

Exhaust ducts • Consider p from CO2

absorption unit

• Later flue gas connection

to capture unit (T-branch)

Flue gas fan • Upgradable design

• or additional space for

installation of second

fan downstream of FGD



HIoPE

Challenges

The biggest challenge is the design of LSB.

Approximately 40% of LP steam has to be extracted from the cross-over pipe.

The varying flow will change the last stage loading and may turn the stage into turn-up mode.

In this case, windage heat is generated near the hub region because rotating LSBs feed energy into the

trapped steam. Thus, water spray nozzles are installed at the exhaust section to cool the high temperature

steam.

Typically, large coal-fired power plants have two- or three LP turbines. Therefore, one could be removed from

operation when the plant is operated in capture mode.

However, plants have one LP turbine may have lower performance when the plant is operated in capture

mode because of turn-up loss. Therefore, a true capture ready plant is not feasible in this case, and the plant

has to be modified when changed for capture operation.



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Advanced USC 4

USC Materials 6

USC Steam Turbine 1





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Substantial reduction in emissions from coal-fired power plants can be achieved only by employing most

advanced and highly efficient modern power generation technologies.

The most direct and economical method for this is the evolutionary advance of increasing steam

temperatures and pressures at the steam turbine inlet well beyond the critical point of water.

To allow this increases, advanced materials are needed that are able to withstand the higher temperatures

and pressures in terms of strength, creep, and oxidation resistance.

USC power plants have faced particular challenges for maintaining equipment reliability and flexible

operation at more advanced throttle steam conditions.

One of most important aspects is the role of pressure on steam-side oxidation.

Most of the efficiency increase results from increased temperature, not pressure.

As a consequence, material requirements, in terms of high temperature strength and steam side oxidation,

could lead to the use of lower pressures (than the goal of 38.5 MPa) to make USC turbine economical, and

yet still beneficial in terms of efficiency increases.

Since ferritic steels are capable of meeting the strength requirements up to of approximately 620C, there is

no obstacle for USC technology within this temperature range.

As the steam condition moved to A-USC, ferritic and stainless steels will be replaced by nickel based alloys

because those have higher material strength and corrosion resistance.

Advanced material application, especially of titanium for LSB with lower density allows longer blades to be

used and thus the exhaust annulus area to be increased.

Generals


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Importance of Fireside Corrosion


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Alloy Strength

H282

IN740

H230

TP310HCbN

IN617

S304H

T24

T92

TP347H

T22

T12

1100 1200 1300 1400 1500 1600 700 800 900 1000

Temperature, F

Allo

wa

ble

Str

ess, ksi

50

45

40

35

30

25

20

15

10

5

0

Ferritic Nickel Alloys

Au

ste

nit

ic


HIoPE

Temperature Capability of Materials

Alstom


HIoPE

600 650 700 750 500 550

Temperature, C

10

0,0

00

h C

ree

p R

up

ture

Str

ess, M

Pa

275

250

225

200

175

25

HCM25 7CrMoTiB1010 HCM12

P92 Super 304 Nf709 174

617 Pipe 617 Tube Alloy 263/740

150

125

100

75

50

Creep Rupture Stress

Candidates of AD 700 Materials

Thermal expansion coefficients, hardness, toughness and other mechanical properties are important to the

design and fabrication of materials. In addition, welds and weldments for both thick sections and tubes should

be tested. To achieve 1400F (760C) steam temperatures, longer creep rupture strength test at higher

temperatures is very important to the A-USC design.


HIoPE

Net Efficiency and Materials


HIoPE

Carbon Steel

CrMo Low Alloy Steel

9-12% Cr Steel

18%Cr-8%Ni Steel

15%Cr-8%Ni Steel

20-25% Cr Austenitic Steel

High Cr-High-Ni Steel

Ni-Base

Alloys

Allowable Temperature at 49 MPa, C

Re

lative

Ma

teria

l C

ost

400 500 600 700 800

200

100

50

10

5

1

Relation between Allowable Metal Temperature at the Allowable Stress of 49MPa and the Relative Material Cost


HIoPE

Alstom

Material Validation


HIoPE

Nozzle box 12Cr cast steel

HP internal casing

12Cr cast steel

Main steam stop valves

12Cr cast steel

Main steam Inlet short pipe

9Cr-1Mo steel

Combined reheat steam valves

12Cr cast steel

Reheat steam inlet short pipes

9Cr-1Mo steel

No.1 IP internal casing

12Cr cast steel

HP IP

Main steam inlet flange elbow

9Cr-1Mo steel

Cooling structure with main steam leading pipe

Overlay coating Protection of No.s 1,2 journal thrust bearing

Rotor cooling for IP section (Protection of aged bending)

Control valves 12Cr cast steel

H-IP Combined Type 600ﾟC / 600C to 620ﾟC

Steam Temperature

HIP Rotor 12Cr steel

USC Materials

Hitachi


HIoPE

질의 및 응답

작성자: 이 병 은 (공학박사) 작성일: 2015.02.11 (Ver.5) 연락처: [email protected]

Mobile: 010-3122-2262 저서: 실무 발전설비 열역학/증기터빈 열유체기술

8. usc steam turbine - engsoft power lab - engineering, …€¦ · · 2015-05-11usc steam...

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