at temper at or

8/2/2019 At Temper at Or

1/8

CCI DRAG

DA-90DSV

Attemperator


2/8

CCIDRAGDA-9

0DSVA

ttemperator

DA-90DSV Attemperator application

discussion

Minimizes Leakage Handles High Thermal Stresses

Enhances Controllability

Prevents Cavitation Damage

Meets Common Face-to-ace

Dimensions

Lowers Maintenance Costs

Reduces Erosion Damage Increases Plant Efciency

Figure 1: Typical HRSG schematic

With each new operating season, the limits o inter-stage attemperatorsin Heat Recovery Steam Generators (HRSGs) are being tested. As plants

search or the most economical operation, be it cycling daily or operating

at reduced loads or extended hours, reliability and operability o the

superheat (SH) and reheat (RH) inter-stage attemperators consistently

come into question. Whether it is a constantly leaking attemperator

that must be repaired or replaced every outage, or a more catastrophic

ailure like a boiler tube leak or a ruptured steam line, the headaches and

rustrations associated with inter-stage attemperation are becoming all

too amiliar to plant managers, operators, and maintenance personnel.

2

Flash

Vessel

Spraywater

DA-90 DSV

SH-Interstage

Attemperator

Economizer

Reheater

Reheater

Superheater

Superheater

Steam Generator

Boiler

DA-90DSV

RH-Interstage

Attemperator

Spraywater

IP/LP

Turbine

HP

Turbine

HRSG

From HP

Turbine Exhaust

Figure 2: Illustrations o damage due to thermalcycling, oten caused by poor attemperatorperormance

Symptoms o Faulty Attemperators

Some o the rst signs o trouble start with uncontrolled spraywater fow

and leakage. Scheduled inspections oten reveal:

nDamaged spray nozzles

nCracked attemperator housings

nDamaged seals

nCracked steam pipes and boiler tubes

nCracked/broken thermal liner

The root cause o most inter-stage attemperator problems can be traced to

our main system/installation parameters:

nHigh pressure drop through the spraywater control portion o theattemperator

nHigh thermal stresses caused by large temperature dierencesbetween the steam and the cooling water

nPoor atomization o the cooling water leading to large amounts ounevaporated water in the steam line

nPoor installation with short distances to downstream elbows,

temperature sensors, or HRSG reentry points


3/8

CCIDRAGDA-90DSVAttemperator

3DRAG DA-90DSV Attemperator

Faulty Attemperator DesignMany o the common interstage attemperator systems overlook several or

all o the root causes o ailure listed on the previous page. Such designs

will lead to problems in your plant, its only a matter o time! Consider

the ollowing:

Single Stage Pressure Drop Problem

When using xed speed pumps, the pressure drop in some inter-stage

attemperator spraywater systems can reach levels greater than 2000 psi

(133 bar). This high pressure drop will severely damage and prematurely

wear a single stage control element causing wire draw, leakage, and

cavitation damage (See Figure 3). The key to eliminating this root cause

o ailure is to incorporate multiple stages of pressure drop in a controlvalve trim. CCIs DRAG Velocity Control Trim can easily package up to

20 stages o pressure drop in attemperator systems to handle the large

pressure drop o the spraywater system.

Valve Trim in the Steam Flow Problem

As allowable operating temperatures increase, inter-stage attemperators

can see steam to spraywater temperature dierences near 700F (390C).

This high temperature dierence in conventional attemperator designs

will lead to high thermal stresses. An attemperator design, such as the

one shown in Figure 4, that locates tight clearance control elements (i.e.

valve trim) in an environment that sees these drastic temperature swings

will ail. Common ailures such as cracked attemperator bodies, cracked

attemperator welds, cracked attemperator nozzles, stuck or seized plug

and stem elements, and even packing leaks can all be attributed to a

design that neglects to account or the high temperature dierence in this

application. To avoid these problems, location is the key. Tight clearance

valve trim components should be moved out o the steam pipe and away

rom the hot steam temperatures.

Pressure Boundary and Tack Welds Problem

Due to the nature o the application and the operation o todays HRSGs,

interstage attemperators will always be exposed to thermal cycling. Welds,

and the heat aected zones around them, are vulnerable to cracking when

put through thermal cycles while also being exposed to high pressure

loads and bending stresses. A properly designed interstage attemperator

eliminates all welds by using a one-piece Chrome Moly orging, thus

removing the risk o cracking in the attemperator body.

Problems Solution

High pressure drop in a single stage Use multiple stages of pressure drop in a DRAG Velocity Control Trim

Expose attemperator to high thermalstresses by locating trim components in

the hot steam pipe

Move the valve trim to a safer environment outside of the steam pipe and

away from harsh thermal stresses

Use pressure boundary welds and tack welds Eliminate all welds by using a one-piece Chrome Moly forging

Figure 3: Cavitation damage on plug

Figure 4: Section view o a conventional

attemperator design


4/8

CCIDRAGDA-9

0DSVA

ttemperator

DRAG DA-90DSV Attemperator eatures4

BeneftsDRAG

DA-90DSVCompetition

n Provides the Valve Doctor Solution. CCI works with plant

operators to improve plant perormance, reliability and output.

n Prevents Cavitation Damage. CCI works in accordance with

ISA guidelines to ensure cavitation is avoided.

n Eliminates Erosion Damage. By controlling uid velocities,

erosion is eliminated.

Multi-stage DRAG

Disk Stack Technologies

Limits uid velocities, controlsvibration and erosion. Multiple

Cv disks throughout disk stack

allow or characterized design

with optimum control throughout

all operating conditions

Stem Packing

Graphite packing is standard

or high temperature service

Water

Inlet

Customer

Connections

Class V Shut-o

A metal seat is

standard, with a

500 PLI (9 kg/mm)

loading orce to

achieve tight

shut-o

Disk Stack

Labyrinth

Grooves

This section o

the disk stack

has no ow

passages; in

their place

labyrinth

grooves break

up clearanceow, preventing

seat ring

damage


5/8


Use check list to evaluate the benefts o CCIs DRAG DA-90DSV Attemperator 5

Spray Nozzle

The variable orifce spray nozzle used in

the DA-90DSV provides excellent primary

atomization and high rangeability. The design is

proven through decades o installation in high

temperature steam applications. Multiple nozzle

designs (as pictured) are available or highcapacity installations

n Thermal Stress Analysis. CCI accounts or all thermal

stresses in the attemperator design.

n

Stops Costly Maintenance Cycles. CCI valves are designedand sized to provide longer intervals between maintenance and

allow easy access to all components.

n Eliminate Thermal Damage to the Trim. Control element is

located outside o the hot steam ow.

n Proven Desuperheating Experience.

BeneftsDRAG

DA-90DSVCompetition

No Trim in Steam Flow

Many probe designs place valve

trims in the steam ow, exposing

them to high steam temperatures

and very large thermal stresses.

The DA-90DSV moves all tight

clearance trim components out

o the steam ow and out o the

harmul thermal environment

Tapered Profle

The attemperator is designed with

a tapered profle to minimize any

vibrations caused by harmonic

requencies associated with

vortex shedding. This becomes

especially important as pipe sizes

increase and the length o the

attemperator increases

Forged Design

A ully orged one-piece Chrome

Moly design eliminates the need

or welding, and eliminates the

risk o welds ailing due to the

high thermal cycling and stress o

the surrounding environment

Low

Flow

High

Flow


6/8

CCIDRAGDA-9

0DSVA

ttemperator

6DA-90DSV Attemperator Solutions

Figure 6: Characterized Equal Percentage DRAG diskstack trim

% Flow100

90807060504030

20100

0 10 20 30 40 50 60 70 80 90 100

% Stroke

Modified

Linear

Linear

ModifiedEqual %

Eliminate Cavitation with DRAGDRAG trim orces the fuid to travel through a torturous path o turns

(Figure 5). Each turn causes a pressure loss in the fuid, and the pressure

gradually reduces as the fuid fows through the multiple turns. This

series o multiple pressure drops controls the fuid velocity and allows

the pressure to reduce without alling below the vapor pressure, thus

avoiding cavitation and the destruction to the valve and trim that can

come with it. The DRAG multistage pressure drop trim provides a clear

benet in terms o perormance and maintenance costs when cavitation is

a concern.

Accurate Control and Reliable Operation at all Flow

Conditions with the CCI DRAG Disk StackDRAG disk stacks can be customized to provide the required Cv

throughout the valve stroke. This is accomplished by conguring disks

with various numbers o turns within the stack (Figure 6). Thus, the

DRAG control valve disk stack can be designed or many dierent fow

characteristics, i.e. linear, equal percentage, or modied equal percentage

(Figure 6). The disks at the bottom o the disk stack, close to the valve

seat, are equipped with a higher number o pressure letdown stages (up to

20 stages or more) to provide critical protection o the seating suraces on

the plug and seat ring. As the valve strokes open, ewer pressure letdown

stages are used or more capacity as the process requires, providing

good control over the entire range o fow conditions. Independent and

isolated fow paths are used to eliminate short circuits between fow paths

and provide the best result in pressure letdown.

Reliable Long Term Shuto

The DRAG control valve uses a hard seat material and a very high seat

loading to provide reliable and repeatable long term shuto in very high

pressure dierential applications. The actuator is sized to provide a

minimum seating load o 500 lb/in (9 kg/mm) o seat ring circumerence,

as recommended by ISA guidelines. The DRAG velocity control trim

design, combined with the high seating orce or shut-o, protects the

seating suraces rom cutting and pitting due to erosion or wire draw.

Benefts o DRAG Velocity Control Trim

n Prevents Cavitation Damage

n Improves Plant Perormance

n Eliminates Erosion Damage

n Lowers Operating Costs

n Reduces Maintenance Costs

n Reduces System Complexity

n Avoids Plant Shutdowns

n Provides Accurate Temperature Control

Figure 5: Each turn in the DRAG trim is a singlestage o pressure drop, eliminating potentiallyharmul kinetic energy

Multiple

Inlet FlowChannels

PressureEqualizing Ring(PER) Grooves


7/8


6 (153mm)MINC

STEAMCONNECTION

WATERINLET

HEIGHT

B

A

7Technical Specifcations

No Name Material

1 Body ASME-SA217-WC9/C12A

2 Bonnet ASME-SA182-F22/F91

3 Spindle INCONEL 718

4 Guide Bushing 300 SS

5 Gaskets Graphite/300 SS

6 Seat 300 SS

7 Disk Stack INCONEL 718

8 Packing, Stem Graphite

9 Packing, Spacer Carbon

10 Yoke Carbon Steel

11 Nozzle Housing ASME-SA182-F22/F91

12 Spray Nozzle ANSI 616

7

6

4

5

3

59

8

10 2

1

12

11

MIN BORE, D

Trim SizeWater

Flange

Steam

Flange

ANSI A B CDia.

D(4) Height

(2) Weight

3/8, 5/8, 1(10, 15, 25)

1.5 RF(40)

3.0 RF(80)

600-15009.0(229)

6.0(152)

19.7(500)

2.9(73.7)

34(865)

~300 lbs(140 kg)

25009.5(241)

7.0(178)

1.5(40)

2.5 RF(65)

4.0 RF(100)

600-250012.25(311.2)

12.25(276.4)

3.81(96.8)

51(1295)

~500 lbs(230 kg)

Nom. Pipe Dia.Length

(see note 3 & 6)

10-14(250-350) 14.12(358.6)

16-20(400-500) 17.75(450.8)

>20 (>500) 21.25 (539.8)

Notes:1. Contact actory or other sizes2. Given is maximum; add 15 (380 mm) or manual override3. Customer ange height will vary to center nozzle(s) in steam pipe4. Customer supplied anged connection5. Numbers in brackets give dimensions in millimeters6. Custom probe lengths available or retroft projects


8/8

DRAG is a registered trademark o CCI.2007 CCI 880 05/11/07

Throughout the world, companies rely on CCI to solve their severe service control valve

problems. CCI has provided custom solutions for these and other industry applications for

nearly half a century.

CCI AustraliaPhone: 61 2 9918 4094

21 Catalina Crescent

Avalon, NSW 2107

Australia

CCI Austria(Formerly Spectris Components GmbH)

Phone: 43 1 869 27 40

Fax: 43 1 865 36 03

Lembockgasse 63/1

AT-1233 Vienna

Austria

CCI China - Beijing

Phone: 86 10 6501 0350Fax: 86 10 6501 0286

Fortune Plaza, 7 Dong San Huan

Zhong

Room 606 Oce Tower

Chao Yang District 100020

Beijing

China

CCI China ShanghaiPhone: 0086 21 64851331

Fax: 0086 21 64851328

Room 1003-1004 Xinyuan

Technology Tower

No. 418 Guiping Road

Shanghai 200233

China

CCI Houston (Repair Center)Phone: 713 869 5233

3409 Brinkman

Houston, TX 77018

USA

CCI IndiaPhone: 0091 80 4030 3500

SJR iPark, 6th Floor, Warp Tower

Plot No. 13, 14 & 15, EPIP Zone

Phase 1, Whiteeld Road

Bangalore East

Bangalore 560 066

India

CCI sales ofces worldwide.

CCI Italy - FlorencePhone: 39 0571 5953203

Via DellIndustria 13

50056 Montelupo Fiorentino (Fl)

Italy

CCI Italy MilanPhone: 39 02 4671 2274

Via Vincenzo Monti 8

20123 Milano

Italy

CCI KK Kobe CityPhone: 81 78 991 5910

6-2-2 Takatsukadai, Nishi-ku

Kobe City

Hyogo 651-2271

Japan

CCI Japan - TokyoPhone: 81 3 5402 3100

4th Floor Terada Bldg.

2-3-3 Shibakoen

Minato-ku, Tokyo 105-0011

Japan

CCI Korea SeoulPhone: 82 (0)31 980 9960

10F, Sinwon B/D,

210-1, Hangangno-2GA

Yongsan-Gu

Seoul Korea

CCI Korea Gimpo CityPhone: 82 31 980 9800

# 26-17, Pungmu-Dong

Gimpo-Si, Gyeonggi-Do

Korea

CCI Middle East - DubaiPhone: 9714 886 1477

Light Industrial Unit: BJ04

Jebel Ali Free Zone, Dubai FZS1

UAE

Contact us at:[email protected]

Visit us online for sales and service locations at: www.ccivalve.com

Nuclear

Oil & Gas

Fossil Fuel

CHP

CCI RSM World HeadquartersPhone: 949 858 1877

Fax: 949 858 1878

22591 Avenida Empresa

Rancho Santa Margarita, CA

92688

USA

CCI RussiaPhone: 7 495 941 8660

Europe Square 2, Oce 611

Moscow 121059

Russia

CCI South AfricaPhone: 27 13 690 3305

Shop 4, 14 Arnhem Singel

Die Heuwel

Witbank 1035

South Arica

CCI Sweden(Formerly BTG Valves)

Phone: 46 533 689 600

Fax: 46 533 689 601

Industrigatan 1-3, Box 603

SE-661 29 Safe

Sweden

CCI Switzerland(Formerly Sulzer Valves)

Phone: 41 52 264 95 00

Fax: 41 52 264 95 01

lm Link 11, P.O. Box 65

8404, Winterthur

Switzerland

CCI Technology Centre UKPhone: 44 (0) 161 655 1690

Unit A3, Brookside Business

Park

Greengate, Middleton

Manchester M24 1GS

UK

at temper at or

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