Mercury Control and Mercury Stability in Byproducts - Mercury Emission and its Control in Chinese Coal-Fired Power Plants - page 111

5.3.1.7 Hg 0 Adsorption Ability of Activated Carbon

Two different groups of C/Hg (mass ratio of active carbon to mercury) were de-
terminated from the same entrance concentration of Hg 0 by changing the quality of
AC. The adsorption experiment was conducted in BL gas, with a temperature of 125
°C. Other experimental conditions are shown in Table 5.3.

Table 5.3 Experimental conditions of different C/Hg ratio

Hg 0 (g/m 3 ) Sorbent Quality (mg) Gas flow (L/min) Adsorb time (min) C/Hg

AC1 10.3 19.3 1 65 8210:1

AC2 44.7 19.3 1 135 17156:1

The adsorption kinetic curves of Hg 0 obtained through AC under different C/Hg
ratios are shown in Fig. 5.10. The adsorption efficiency of Hg 0 by AC under high
C/Hg was higher than that under a low ratio. However, the adsorption quantity of
unit AC decreased under high C/Hg and reduced the utilization efficiency of AC. In
the course of practical engineering application, a mere increase in C/Hg was
sometimes insufficient to ensure good results.

30

25

20

15

10

AC1 10.3 mg
AC2 44.7 mg

5

0

0 15 30 45 60 75

Time (min)

Fig. 5.10 Hg 0 adsorption by AC at different C/Hg ratios

5.3.2 Mercury Adsorption Ability of Modified Sorbents

Experimental research on mercury adsorption with modified sorbents was con-
ducted in order to screen out those with high efficiency and low cost. Several sor-
bents, including coal-fired fly ash, zeolite, vermiculite and bentonite, were modified
according to the following modified methods:
1) Dipping treatment of Na 2 S;

2) Dipping treatment of KMnO 4 ;

3) Dipping treatment of active MnO 2 ;

4) Dipping treatment of Mn(NO 3 ) 2 ;