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The 2 nd annual Air-Cooled Condenser User’s Group Meeting. Air-Cooled Condensate Polishing in China. WenhuaTian Huiyong He Xi’an Thermal Power Research Institute Co Ltd.(TPRI), China September 28-29, 2010 Pueblo. CONTEXTS. I. Introduction of TPRI

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Presentation Transcript
slide1

The 2nd annual Air-Cooled Condenser User’s Group Meeting

Air-Cooled Condensate Polishing in China

WenhuaTian Huiyong He

Xi’an Thermal Power Research Institute

Co Ltd.(TPRI), China

September 28-29, 2010

Pueblo

contexts
CONTEXTS

I. Introduction of TPRI

II. Developments of ACCs in China

III. Carbon Dioxide in ACCs

IV. DO Controlling in ACCs

V. Case of Indirect ACCs

outline
The distribution of coal and water resources in China is asymmetric; coal-rich regions typically lack water and vice versa

Because of its significant water-saving advantage, ACC is suitable for drought-prone regions in northern China. So the government of China required that all the new built coal power plants should be used ACCs in drought-prone regions after 2002

The use of ACCs has increased rapidly in China within the past five years

Outline
development of accs
The total capacity of ACCs was about 24,000MW by 2007

The percentage of ACCs was 4.3%(Total capacity of coal power plant was 554,000 MW)

The number of constructing sub-critical ACC plants was 47, and the capacity was 46,000 MW (2008 ~ 2009)

Development of ACCs
slide7
It is estimated that the total capacity will reach 1,200,000MW until 2015 in China

Capacity of coal power plant will be 820,000MW

Capacity of ACCs will surpass 100,000MW and occupy 12%

Foreground

slide8
Direct ACCs were the majority, occupied 93% in 2007

Indirect ACCs developed rapidly after 2008. Up to now, the operation capacity is 4,200MW, and other units with 16,800MW capacity is constructing

Ratio of Direct & Indirect

slide10
Direct ACCs were the majority, occupied 93% in 2007

Indirect ACCs developed rapidly after 2008. Up to now, the operation capacity is 4,200MW, and other units with 16,800MW capacity is constructing

Ratio of Direct & Indirect

analyzer method instrument
Analyzer method & Instrument

Because carbon dioxide in high pure water such as condensate is as low as μg/L(ppb) level , it is difficult to sample and determine.

Trace carbon dioxide analyzer(Sentry Co. ) can measure carbon dioxide in high pure water as low as ppb level on-line.

Advantages:

(1) convenient and quick testing process

(2) high accuracy, good repeatability and high sensitivity

Standard:

D 4519-94(Reapproved 2005)by ASTM

slide19

Determination Methods

This test method measures the electrical conductivity of high purity water through a cation exchanger in the hydrogen form, then through an electric reboiler. The effluent was boiled at atmospheric boiling water temperature after acidic (volatile) gas removal. subsequently, it was cooled at 25℃. Passage through the cation resin replaces cations (including ammonia and amines)in the water with hydrogen ions. Two conductivity cells located in the instrument provide measurements of the cation conductivity at the incoming sample temperature, and the effluent conductivity at 25℃.

In order to obtain the carbon dioxide, subtract the conductivity of pure water (0.055μS/cm) from the conductivity of the final effluent cell. Then deduct this value from the cation conductivity obtained from the cell immediately after the cation exchanger resin. Use this adjusted conductivity value to look up the concentration of volatiles expressed as a concentration of carbon dioxide in Table.

slide20

Tongchuan Power Plant

(2×600MW,Shaanxi Province)

Powdex of Tongchuan Power Plant

slide21

Shangan Power Plant

(2×600MW, Hebei Province)

CA-AN Bed of Shangan Power Plant

slide22

Determination Results

  • At the same pH condition, the higher level of CO2 , the higher level of Fe in the condensate
  • CO2 recycles in plant A, but it is removed in plant B by separated beds in plant B
  • It is important to control the level of CO2 , it will reduce corrosion of metals in ACCs.
slide24
DO in condense will make iron corroded in ACCs, so the limit DO concentration is 100ppb in China

The operational ACCs in condense often surpass the limit of 100ppb

Determination of DO

slide25

Zhaoguang Power Plant

(2×300MW+2×600MW,

Shanxi Province)

Yushe Power Plant

(2×300MW,Shanxi Province)

slide26

Wuxiang Power Plant

(2×600MW,Shanxi Province)

Hejin Power Plant

(2×300MW,Shanxi Province)

slide27

Determination results of DO

The reason of high DO in condensate:

1. Vacuum system is too large that will lead to air leakage in ACCs.

2. DO in make-up water is too high. For example, it is 800 ppb in some power plant .

slide28
Strengthen the welding management and improve its quality, try to decrease the air leakage of vacuum

System retrofitting----Case

Methodsto decrease DO

slide31
Yangcheng Power Plant is located in Shanxi province in China.

The first stage project are 6×350MW subcritical WCCs,which was completed at 1997.8.

The second stage project are 2×600MW subcritical indirect ACCs named SCAL, which began to construct at 2005.5.18 and completed at 2007.9.

Basic Information

  • The SCAL ACCs is produced by EGI company(Hungary), and it is more like the combination of Harmon’s no tower system and Heller’s cooling tower.
slide32
Cooled water recycles closely during operation, no water consumption

High heat -exchange efficiency

The corrosion rate of condenser can be controlled by adjusting pH in recycled water in order to prolong service cycle time of condenser

Less power consumption

The volume of air cooling tower is small

Simple system, convenient operation and less capital construction investment

Features of SCAL indirect ACCs

slide33
Unit 7 & 8 of Yangcheng Power Plant are indirect ACCs. 3 sets of powdex are used for each CPP.

Powdex shows good filtration abillity for crud, but its desalination capacity is weak, so steam quality of the units didn’t reach the standard for most of running time.

In order to improve the steam quality, retrofitting of CPP was carried out. 2 high-speed mixed beds were added after powdex

The retrofitting has been successfully completed and put into operation in March 2009, and achieved desired results.

CPP Introduction

slide34

Steam quality of unit 8 before retrofitting

2007.8-2008.9

SiO2, organism, CO2 and other impurities in condensate couldn’t be removed after powdex. It is just depended on boiler blowdown. This is the main reason of high conductivity in steam.

slide35

Steam quality of unit 8 after retrofitting

2009.3

After retrofitting, conductivity in the system decreased clearly. The effluent quality of high speed mixed beds is still good after nearly 1 month operation. It achieved the desired results.

slide38

Wenhua Tian:86-029-82102246(Office)

86-13991302260

Email:[email protected]

Huiyong He:86-029-82102570(Office)

86-13609111635

Email:[email protected]

mixed bed
Mixed Bed

Cylindrical MB

slide40
Strengthen the welding management and improve its quality, try to decrease the air leakage of vacuum

System retrofitting----Case

The condensate tank was combined to the exhaust air cooling device. After through the nozzle, the makeup water goes to the throat of exhaust device. It can lead to an increase of the secondary removal of oxygen in returned condensate.

Methodsto decrease DO

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