Environmental Engineering Reference
In-Depth Information
To estimate total annual Hg emissions into the atmosphere from coal-fired
power plants in China, the following formula was used:
n
E
eef
E
(3-2)
total
j
j
j
0
where
f
is the proportion of one type of coal-fired power plant in total number of
coal-fired power plants; and
j
is one type of coal-fired power plant (1
j
n
);
E
j
is the
total mercury emission of the
j
th
type of coal-fired power plan.
The Hg
EMF
i
of burners and flue gas pollution control devices in coal-fired
power plants are shown in Table 3.1.
Table 3.1
Hg
EMF
i
of each device in coal-fired power plants
Devices
EMF
Four-corner burner
0.998
Wet-type dust collector
0.935
ESP
0.867
FGD
0.252
SCR+ESP+FGD
0.124
3.3 Estimation of Mercury Emissions from Coal-Fired Power
Plants in China
Coal production in China amounts to thousands of millions of tons each year, ac-
counting for 40% of the world coal production. Around 50% of this amount of coal
production is used in coal-fired power plants. Fig. 3.1 shows the trend of coal
consumption in coal-fired power plants from 1990 to 2005 in China.
According to a survey of coal consumption among coal-fired power plants in
China, out of the total coal used, washed coal accounted for only 8% of the total.
More than 90% of the total coal-fired boilers widely used in China are pulverized
coal burners. Of these, the four-corner burner is one of the most used burners in
pulverized coal boilers. Since the mid-80s, ESP has been used instead of me-
chanical filters and cyclone separators, with a 4% 5% increase in speed each year.
Before 1996, ESP was about 63.3% of the total dust cleaning equipment, and the
rest consisted of wet dust cleaning equipment. From 1996 to 2000, this increased to
86.3% and increased even further after 2000 to 95%. Almost all of the more than
300 MW coal-fired power plants are equipped with ESPs.
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