EVALUATION OF HIGH-TEMPERATURE DESULFURIZATION OF COAL-GASIFICATION GAS WITH LIMESTONE

Experiments on the reaction between limestone and hydrogen sulfide were conducted with fixed bed and fluidized bed experimental apparatus under high pressures and temperatures. This study made it clear why desulfurization efficiency was low when limestone was directly fed into a coal fluidized bed gasifier. The first reason is that the residence time of limestone in the gasifier is too short. The second reason is that the oxidation rate of CaS is larger than the formation rate of CaS. When the rate of CaS formation was nearly equal to the rate of calcination, the CaS mole fraction of limestone was above 60%. Passing coal gasification gas through a limestone fluidized bed in the fluidized bed experimental apparatus decreased H2S concentration at the fluidized bed to about 140 ppm.