Desulfurization characteristics of fly ash recirculation and combustion in the circulating fluidized bed boiler

Abstract

The experiments of the fly ash recycle combustion using Guizhou anthracite were carried out in a bench scale circulating fluidized bed (CFB) combustor. Effects of some key operating parameters such as recycle ash to coal mass ratio (Ca to S molar ratio), temperature, reactivation mode of fly ash, circulation rate and fluidization velocity on the desulfurization efficiency were intensively investigated. It is shown that the limestone utilization efficiency could be improved about 30% with the following operating conditions: the mass ratio of fly ash (reactivated by water and dried at 90°C) to coal was 0.45, the furnace temperature was 88°C, the water to ash mass ratio was 4.5% (the water-to-calcium molar ratio was 0.55) and circulation rate was 18.