Estimation of Mercury Emissions from Coal-Fired Power Plants in China - Mercury Emission and its Control in Chinese Coal-Fired Power Plants - page 22

200000

Total consumption
Coal consumption

150000

×

100000

50000

1988 1990 1992 1994 1996 1998 2000 2002 2004 2006

Year

Fig. 3.1 Coal consumption of coal-fired power plants in China from 1990 to 2005

Before 2000, dust cleaning equipment was the only flue gas pollution-control
device in coal-fired power plants in China. According to statistics, in 2000 flue gas
desulfurization devices were installed to cover about 4,000 MW of power output,
accounting for just 1% of the total installed capacity of coal-fired power plants in
China. In 2005, the amount of new gas desulfurization devices increased to cover
104,000 MW of power output, which was more than the total of 46,000 MW re-
corded 10 years before. At the end of 2010, the amount of desulfurization reached
460,000 MW in China. At present, SCR has already started to be used for control-
ling the NO x emissions in China.
Based on the flue gas cleaning devices recorded in 2002, coal-fired power plants
could be divided into two types in China: one type was only equipped with ESP
(about 88% of the total coal-fired power plants), and the other was equipped with
ESP and WFGD (about 12% of the total).
According to the above analysis, the calculated mercury emissions into the
atmosphere from 1990 to 2005 from coal-fired power plants in China are presented
in Fig. 3.2. The comparison in the growth rate of coal consumption and mercury
emissions from 1990 to 2005 of coal-fired power plants in China is shown in Fig.
3.3. Based on Figs. 3.2 and 3.3, the increment of mercury emissions from coal-fired
power plants was not maintained at the same speed, which was similar to the trend
in coal consumption from 1990 to 2005.
WFGD can remove great amounts of Hg 2+ by washing. With the increasing use
of WFGD, coal-fired power plants emitted lesser mercury per ton of coal con-
sumption from 2003 to 2005 (Figs. 3.2 and 3.3). Mercury emissions from coal-fired
plants reached 119.7, 134.3, and 150.6 tons in 2003, 2004 and 2005, respectively.
With the assumption that the use of pollution devices was the same as in 2002, the
mercury emissions would be 131.6, 147.6 and 165.1 tons in 2003, 2004 and 2005,
respectively, which were 11.8, 13.3, and 14.5 tons more than those actual mercury
emissions in 2003, 2004 and 2005. When SCR was used, WFGD removed more
mercury because there was more Hg 2+ existing in the tail of the flue gas.