Environmental Engineering Reference
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reaction shown in Eq. (4-7) rapidly occurred. When the temperature reached over
400 °C, the reverse reaction shown in Eq. (4-7) rapidly occurred, and part of HgO
decomposed into mercury and oxygen. The resultant HgCl in reaction Eq. (4-9) had
an unstable form, which further occurred in reaction Eqs. (4-4), (4-5), and (4-6) to
produce stabilized HgCl
2
.
4.2.2 Mercury Speciation in Flue Gas When Coal Combustion Is in
a State of Suspension
Yanzhou (YZ) and CG coals were used to study the mercury speciation in the
suspension pulverized coal boiler at different temperatures of 1,300, 1,200, and
1,100 °C. The results showed that total Hg
(g)
(including Hg
2+
and Hg
0
) ranged from
10 to 15 g/(N·m
3
). The distributions of mercury speciation in the flue gas are
shown in Figs. 4.6 and 4.7 when YZ and CG coals were burning, respectively. The
speciation distributions of the Hg
(g)
of the YZ and CG coals were similar in that Hg
0
concentration was higher than Hg
2+
concentration at different temperatures.
65
60
55
Hg
0
Hg
2+
50
45
40
35
1100
1150
1200
1250
1300
Temperature (°C)
Fig. 4.6
Hg
(g)
speciation distribution of YZ coal combustion in a state of suspension
65
60
55
Hg
0
Hg
2+
50
45
40
35
1100
1150
1200
1250
1300
Temperature (°C)
Fig. 4.7
Hg
(g)
speciation distribution of CG coal combustion in a state of suspension
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