Regeneration of FGD Dry-Sorbent Materials. Phase I. Final Report

摘要

Sodium-based sorbent injection directly into the flue gas duct of a coal-burning power plant has been investigated since 1975 by GFETC (using laboratory and pilot plant apparatus) as an SO sub 2 control technology. Regeneration of sorbent from spent sorbent material is highly desirable to reduce the sorbent cost, and to alleviate the leaching and potential pollution problems of soluble sodium compounds when disposing of spent sorbent materials in landfills. The work reported herein was initiated to develop a continuous, aqueous-based process for regeneration of sodium carbonate-type sorbents from spent sodium-base sorbent/flyash materials. Specific project objectives are to: (1) retain process simplicity and to avoid difficult process conditions; (2) maximize recovery of sodium from spent sorbents; (3) minimize process costs and energy requirements; (4) maximize reactivity of the regenerated sodium bicarbonate sorbent; and (5) produce process waste materials that may be disposed of in an environmental acceptable manner. The sorbent regeneration process which has been developed during the laboratory investigation (Phase I) of this project may be divided into three parts: (1) leaching of the spent sodium-based sorbent; (2) conversion of the leachate to a NaCl brine; and (3) production of NaHCO sub 3 (regenerated sorbent) using commercially-proven Solvay (ammonia-soda) process technology. Significant results from the laboratory study are as given.