Coal gasification and sulfur removal process

摘要

An improved coal gasification process employing fluid bed reactors is disclosed. In the improved process, sulfur absorption on limestone is balanced between gasification and spent solids combustion stages. Part of the sulfur is absorbed during gasification with an in situ alkaline sorbent to form a fuel gas. The raw fuel gas is fed to a metallic sorbent desulfurization reactor to remove residual sulfur. The spent metallic sorbent is regenerated with air, steam or a combination thereof, forming a regeneration offgas containing sulfur. The offgas is recycled to the combustion stage where the sulfur is absorbed on the alkaline sorbent from the gasifier. Substantially complete oxidation of sulfides in the limestone sorbent to sulfates can thus be promoted in the combustion stage to substantially eliminate sulfides from process waste solids.