Set up of a fluidized bed reactor for mercury vapor capture by powdered activated carbon

The use of a bubbling fluidized bed of inert material to improve the activated carbon mercury capture efficiency from combustion flue gas is explored. To this end, elemental mercury (Hg0) capture experiments have been conducted in a purposely designed lab-scale pyrex reactor operated either as a fluidized bed or as an entrained bed. 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 fluidized bed configuration led to an increase of the mercury capture efficiency and of the activated carbon utilization with respect to the entrained bed configuration. This result was explained by the presence of a larger activated carbon loading in the reaction zone, as a consequence the increased surface area available for activated carbon adhesion/deposition in the fluidized bed.