Environmental Engineering Reference
In-Depth Information
Table 5.2
Reliability of the adsorption mechanism test system
Contrastive
experiment
Inlet of Hg concentration
(g/m
3
)
Outlet of Hg concentration
(g/m
3)
Percent
(%)
No. 1
17.75
15.75
88.76
No. 2
17.75
20.84
117.42
No. 3
17.75
17.48
98.47
No. 4
17.75
19.42
109.40
5.2.2 Adsorption Efficiency and Adsorption Capacity
Adsorption efficiency and adsorption capacity were both used to represent the
adsorption ability of mercury by the sorbent. The breakthrough curve shows the
change in mercury concentration at the exit of the fixed bed over time. The ordinate
(
C
/
C
0
100%) of the breakthrough curve is the ratio of mercury concentration (
C
) at
the exit of the fixed bed to the initial mercury concentration (
C
0
) at the entrance of
the fixed bed. The breakthrough curve represents the mercury concentration
changes within the adsorptive layer, and its shape relies on the type of sorbent and
the characteristics of simulated flue gas. The break is defined as the appearance of
mercury at the exit of the fixed bed during the adsorption process. Break time is the
accumulated total time between the start of adsorption and the break appearance.
Adsorption efficiency can be defined as (1
C
/
C
0
)100%, which is the percentage of
mercury removal from simulated flue gases by sorbent.
The adsorption capacity of a unit sorbent at some time
t
(g Hg/g) is the ratio of
the amount of mercury adsorbed to unit mass of the sorbent during the start of the
adsorption up to the moment of
t
, as shown in the following expression:
t
q
[ 1
C
/ )d]
C
t
C
/
m
0
0
In the next subsection, we will firstly introduce the different types of adsorbents
and modified adsorption properties. Subsection 5.4 presents the mercury adsorption
mechanism of activated carbon, and after that subsection 5.5 discusses the stability
of the mercury in the sorbent.
5.3 Experimental Research on Mercury Absorption of Different
Sorbents
The mercury adsorption performances of different types of adsorbents are the basis
of studies on sorbent injection mercury control. Corresponding modifications were
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