Process Development in Removing Sulfur Dioxide from Hot Flue Gases. Part 3. Pilot Plant Study of the Alkalized Alumina System for SO2 Removal

摘要

The use of alkalized alumina in removing sulfur dioxide from a coal-combustion flue gas at 625 F was investigated on a pilot plant scale. The absorber was 26 feet long and 1.6 inches ID. Counter-current gas-solids flow at gas velocities of 8 to 15 ft/sec in the presence and absence of baffles, as well as solids entrainment at gas velocities of 20 to 23 ft/sec with solids recycle, were employed. The spent absorbent was regenerated as a fixed bed with the reducing gases--reformed natural gas and hydrogen. Twenty cycles of absorption-regeneration were successfully completed using the alkalized alumina rolled into spherical granules 10 to 16 mesh. There was no loss in activity of absorbent toward SO2 with a modest attrition equivalent to 0.1 percent of the solids feed. Supporting studies were conducted on the effect of the sodium content in the absorbent, the composition of the reducing gas, thermal treatment to increase absorbent hardness, and removal of absorbed chlorine from the absorbent. A mathematical model was formulated to describe the removal of SO2 by alkalized alumina from fixed and falling beds. (Author)