Elemental mercury vapor capture by powdered activated carbon in a fluidized bed

The use of a bubbling fluidized bed of inert material to improve the activated carbon performance for mercury vapor capture is explored. To this end, preliminary mercury capture experiments have been conducted in a purposely designed lab-scale pyrex reactor operated in the fluidized bed and in the entrained bed configurations. Commercial powdered activated carbon was continuously injected in the reactor and both mercury concentration and carbon elutriation rate were followed at the outlet. Transient mercury concentration profiles at the bed outlet showed that the presence of a fluidized bed led to an increase of the mercury capture efficiency and, in turn, of the activated carbon utilization. This result was explained by the larger activated carbon loading and gas/solid contact time in the reaction zone as a consequence the increased surface area available for activated carbon adhesion/deposition in the fluidized bed.