Mercury Speciation Transformation During Coal Combustion - Mercury Emission and its Control in Chinese Coal-Fired Power Plants - page 30

100

80

60

P y rolyzing
C o mbustion 40

20

0

700 800 900 1000 1100 1200

Temperature (°C)

Fig. 4.4 Effect of temperature on Hg 0 during pyrolyzing and burning

100

80

60

Com b ustion
Pyrolyzing

40

20

0

700 800 900 1000 1100 1200

Temperature (°C)

Fig. 4.5 Effect of temperature on Hg 2+ during pyrolyzing and burning

During pyrolyzing, Hg 0 reaction functions with Cl from Cl 2 and HCl in flue gas
were concluded as follows:

0

(4-1)

Hg Cl HgCl

(g) 2(g) 2(s,g)

0

Hg 2HCl HgCl H (4-2)

(g) (g) 2(s,g) 2(g)

0

Hg Cl HgCl

(4-3)

HgCl Cl HgCl

(4-4)

2

HgCl HCl HgCl H (4-5)

2

HgCl Cl HgCl Cl (4-6)

2 2

During burning, Hg 0 reaction functions in the flue gas were concluded as follows:

2Hg

澠澡

O 2HgO

澠 澡 (4-7)

g 2 s,g

0

(4-8)

2Hg 4HCl O 2HgCl 2H O

(g) (g) 2(g) 2(s,g) 2 (g)

0

4Hg 4HCl O 4HgCl 2H O (4-9)

(g) (g) 2(g) 2 (g)

Both HgO and HgCl 2 generated in the reaction, Eqs. (4-7), (4-8) and (4-9), were
compounds of Hg 2+ . When the temperature reached more than 300 °C, the positive