Simulation of mercury capture by activated carbon injection in incineratorflue gas. 2. Fabric filter removal

Following a companion paper focused on the in-duct mercury capture in incin erator flue gas by powdered activated carbon injection (1), this paper is c oncerned with the additional mercury capture on the fabric filter cake, rel evant to baghouse equipped facilities. A detailed model is presented for th is process, based on material balances on mercury in both gaseous and adsor bed phases along the growing filter cake and inside the activated carbon pa rticles, taking into account mass transfer resistances and adsorption kinet ics. Several sorbents of practical interest have been considered, whose par ameters have been evaluated from available literature data. The values and range of the operating variables have been chosen in order to simulate typi cal incinerators operating conditions. Results of simulations indicate that , contrary to the in-duct removal process, high mercury removal efficiencie s can be obtained with moderate sorbent consumption, as a consequence of th e effective gas/sorbent contacting on the filter. Satisfactory utilization of the sorbents is predicted, especially at long filtration times. The sorb ent feed rate can be minimized by using a reactive sorbent and by lowering the filter temperature as much as possible. Minor benefits can be obtained also by decreasing the sorbent particle size and by increasing the cleaning cycle time of the baghouse compartments. Reverse-flow baghouses were more efficient than pulse-jet baghouses, while smoother operation can be obtaine d by increasing the number of baghouse compartments. Model results are comp ared with available relevant full scale data.