Experiments on the effects of coal particle size on the combustion processes in the circulating fluidized bed boiler

The circulating fluidized bed technology has the advantages of high efficiency,low emissions of pollutants and excellent fuel flexibility.There have been many circulating fluidized bed boilers firing Fujian anthracite in Fujian Province.However,problems generally encountered during operation of those boilers are the high carbon content of fly ash and low thermal efficiency.In this paper,combustion experiments were carried out using Fujian anthracite of three different particle sizes on a 75t.h-1 CFB.Temperatures during combustion processes at different particle sizes were measured.The effects of coal particle sizes on the particle distribution and the carbon content of bed ash,the particle distribution and the carbon content of fly ash,and the thermal efficiency of the boiler were determined and analyzed.In addition,some suggestions were made for improving the combustion of the CFB firing Fujian anthracite,which are practicable for engineering application.