Mercury Speciation Transformation During Coal Combustion - Mercury Emission and its Control in Chinese Coal-Fired Power Plants - page 88

Hg 0
94.22%

HgCl 2
0.82%

HgO
4.96%

Fig. 4.82 Hg species distribution ratio after integration with the whole three dimensional furnace
chamber

HCl
99.23%

Cl
0.64%

Cl 2
0.13%

Fig. 4.83 Cl distribution ratio after integration with the whole three dimensional furnace chamber

4.5.2.4 Comparison between One-Dimensional Dynamics Simulation of Rear
Heating Surface and Experimental Results

The rear low temperature section must be calculated due to the fact that the accu-
racy of numerical simulation did not validate test data in the high temperature sec-
tion, although three-dimensional Hg formation and concentration in the furnace
above were precisely simulated. A simple one-dimensional model was employed in
numerical calculation of the complicated rear heating surface owing to the difficulty
of three-dimensional numerical calculation. According to temperature and velocity
parameters, the mean residence time of all temperature sections were calculated.
Then component concentrations in the three-dimensional furnace outlet were taken
into account by the one-dimensional model.
A one-dimensional dynamics simulation was employed to explore homogene-
ous mercury speciation along the rear heating surfaces with help of CHEMKIN3.7.
While it's well recognized that under actual combustion conditions mercury for-
mation and oxidation would be subject to kinetic control, Hall et al . and Widmer et
al . proposed one-step global reaction mechanisms to model the observed depletion
of Hg 0 in the presence of Cl 2 or HCl [11,34,3] . Lia et al . [8] studied theoretical chlorine
reaction in the publication. But such mechanisms provided little insight into the
details of the conversion process, let alone investigated the impact of the other flue
gas components. Recently, much progress has been achieved in unraveling the
reaction mechanism for homogeneous mercury oxidation through a sequence of
elementary reactions. Such investigations had been done by Sliger et al . [6,28,34] . Of
those efforts, in particular Edward et al . [36] provided the most complete mercury