A Two-Stage Reactor for Studying Sorbent Reactivities in Flue Gas Desulfurization Systems Utilizing a Fabric Filter Collector

Abstract

A two-stage reactor has proven superior in understanding the complex reactions involved in dry gas-solid reactions responsible for flue gas desulfurization in the medium temperature range (425–650°C). Traditionally, experimental approaches have concentrated on either the in-duct reactivity portion of these reactions, or the reaction in the particulate collector, usually a fabric filter (baghouse). From these current studies we have found that sorbent injection conditions upstream of a fabric filter affect the continued reactivity of the sorbent on the filter as well. Considering the sorbent reaction history in its upstream injection zone is therefore important. An integrated two-stage reactor system is described which was designed to simulate the sequential sorbent reactions from the injection zone to the filtration stage. The experimental results for Ca(OH)2 reacting with SO2 in a single-stage fixed-bed reactor system are compared with our results for this reaction where sorbent conversions and surface area evolution in a baghouse were simulated. The comparison shows that because of the distinctive conditions in the injection and filtration stages, the sorbent reactions in the injection zone are very different from those in the fixed-bed and they can seriously alter the subsequent sorbent reactions in the filtration stage. The results from the single-stage fixed-bed reactor misrepresent the sorbent reactivity and its physical structural change during the reactions.