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
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
Introduction of TPRI
Developments of ACCs in China
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 droughtprone regions after 2002
 The use of ACCs has increased rapidly in
China within the past five years

Development of ACCs
The total capacity of ACCs was about
24,000MW by 2007

Number o f units
The
Capacity(MW)
Total Capacity(MW)
23
600
13,800
25
300
7,600
11
200
2,200
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)
Foreground
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%

Ratio of Direct & Indirect
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

The percentage of different CPP(2009)
Ratio of Direct & Indirect
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

Dalater Power Plant
（ 4×600MW,Inner Mogolia）
Powdered resin filter
Datang Tuoketuo Power Plant
（ 4×600MW,Inner Mogolia）
Unit 5 high-speed cation bed
Separated bed in Jingjie power plant
（4×600MW,Shaanxi）
Carbon Dioxide in ACCs
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 online.
Advantages:
(1) convenient and quick testing process
(2) high accuracy, good repeatability and high
sensitivity
Standard:
D 4519-94（Reapproved 2005）by ASTM
Trace carbon dioxide analyzer(Sentry Co. )
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.
Tongchuan Power Plant
(2×600MW,Shaanxi Province)
Powdex of Tongchuan Power Plant
Shangan Power Plant
(2×600MW, Hebei Province)
CA-AN Bed of Shangan Power Plant
Determination Results
Type of
condensate
polishing
DO in
condensate
（μg/L）
A
Subcritical
pressure
drum boiler
Powdex
B
Supercritical
Oncethrough
boiler
Prefiltration+
CA -AN
bed
Plant
Type of unit
Fe
(μg/L)
CO2 (μg/L)
pH
Condensa
te
Effluent
of
polishing
Feed
water
85
30
20
15
15.0
9.4
20
12
3
1
8.0
9.4
Condensate
 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.
DO Controlling in ACCs
Determination of DO


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
Zhaoguang Power Plant
(2×300MW+2×600MW,
Shanxi Province)
Yushe Power Plant
(2×300MW,Shanxi Province)
Wuxiang Power Plant
(2×600MW,Shanxi Province)
Hejin Power Plant
(2×300MW,Shanxi Province)
Determination results of DO
Power Plant
Capacity
Start-up time
Hejin
Yushe
2×300
2×300
Zhaoguang
2×300
2005
2004.10
2005.7（#1 unit）
2005.9（#2 unit）
DO in condensate
（μg/L）
70～106
85～237
#1 unit:20～55
#2 unit:52～84
Wuxiang
2×600
2006.10
＜30
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 .
Methods to decrease DO


Strengthen the welding management and improve its quality,
try to decrease the air leakage of vacuum
System retrofitting----Case
Power Plant
Wuxiang
Capacity
2×600
MW
Start-up
time
Before the
retrofitting
the exhaust unit was
installed out of the
condensed water
2006.10.6 tank, make-up water
is supply to external
condensed water
tank
After the retrofitting
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.
DO in condensate after retrofitting
Load
Backpressu
re
（MW） （kPa）
Flow of
Make up
water
（t/h）
Flow of
Condensate
DO
Condensate Temperature （μg/L）
（t/h）
（℃）
360
21.0
28.9
760.9
61.2
＜0.5
500
23.0
50.7
1045.3
63.2
＜0.5
600
20.5
48.2
1269.4
60.7
1.2
600
19.1
18.8
1240.0
60.0
0.7
Case of Indirect ACCs
Basic Information




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.
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.
Features of SCAL indirect ACCs






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
CPP Introduction




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.
Steam quality of unit 8 before retrofitting
2007.8-2008.9
Testing Item
Unit
Standard
Value
Min.
Max.
Qualified Rate
(%)
DO in condensate
μg/L
30
10.8
25.1
100
Conductivity in condensate
μS/cm
0.3
0.100
0.700
78.0
DO in feed-water
μg/L
7
0.1
24.1
92.7
Conductivity in feed water
μS/cm
0.2
0.104
1.810
38.0
SiO2 in feed water
μg/L
20
3.0
37.8
94.5
Conductivity in boiler water
μS/cm
1.5
0.126
2.030
99.7
SiO2 in boiler water
μg/L
200
38.6
520
97.6
Conductivity in main steam
μS/cm
0.2
0.081
0.657
22.5
SiO2 in main steam
μg/L
20
2.9
49
98.0
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.
Steam quality of unit 8 after retrofitting
2009.3
Testing Item
Unit
Standar
d Value
Min.
Max.
Qualified Rate
(%)
DO in condensate
μg/L
30
10.8
22.4
100
Conductivity in condensate
μS/cm
0.3
0.120
0.258
100
DO in feed-water
μg/L
7
2.8
6.8
100
Conductivity in feed water
μS/cm
0.2
0.104
0.195
100
SiO2 in feed water
μg/L
20
5.6
12.5
100
Conductivity in boiler water
μS/cm
1.5
0.126
0.256
100
SiO2 in boiler water
μg/L
200
58.6
125
100
Conductivity in main steam
μS/cm
0.2
0.081
0.159
100
SiO2 in main steam
μg/L
20
4.8
12.4
100
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.
Thanks for your
attention！
Welcome to China！
Welcome to Xian！
Welcome to TPRI！
Wenhua Tian：86-029-82102246（Office）
86-13991302260
Email：tianwenhua@tpri.com.cn
Huiyong He：86-029-82102570（Office）
86-13609111635
Email：hehuiyong@tpri.com.cn
Mixed Bed
Cylindrical MB
Methods to decrease DO



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.