Experimental Research On The Oxygen-enriched Combustion Of Sewage Sludge And Coal In CFB

Urbanization development and sewage industry development have brought about a soaring increment of sewage sludge, how to dispose the ever-increasing sewage sludge and eliminate their hazard has become a serious problem with which people are currently confronted. At present, there are three treatments for the sewage sludge: landfill, farmland utilization and incineration. Method of co-combustion of sewage sludge and coal can finish the final objective of sewage sludge which is to meet the requirements of decrement, stabilization and detoxification. Oxygen-enriched combustion technology is one of the new clean coal combustion technologies that can control pollutant emission, which makes CO2 separation and SO2 treatment become easier, and also is reduces the NOX emission. In order to achieve the purpose of the nuisanceless disposal of sewage sludge and reduce the emission of pollutants in the combustion process, we combined the incineration of sewage sludge in CFB with the oxygen-enriched combustion.This paper carried out the experimental research on the oxygen-enriched combustion of sewage sludge and coal in a CFB incinerator whose diameter of furnace is 100 mm. Experimental analyzed on the combustion characteristics of fuels with different mass rate in the oxygen concentration of 21%~35% and also the effects of fluidized air velocity, oxygen contents and the fluid bed temperature on the composition in the flue gas.This paper analyzed the air resistance of air distribution dampers and the fluidized characteristics of the different material thickness, and we got the critical fluidized velocity and the circulating fluidization velocity, which provided reference data for the thermal test.The purpose of the thermal test study in the following several aspects:①The air-coal ratio of practical operation in the beginning of initiating phase;②The effect of fluidized velocity on the temperature of dense phase region with different ratio of coal and sludge.③The change of combustion temperature along the furnace height with different ratio of coal and sludge and different O2 concentration.④The effects of fluidized velocity, oxygen contents and the fluid bed temperature on the composition in the flue gas. During this pilot study, the following main conclusions:①The critical fluidized velocity is 0.15m/s and the circulating fluidization velocity is 1.8 m/s;②The air-coal ratio of practical operation was 9~15 (m3/kg) in the beginning of initiating phase;③The temperature of dense phase region decreased with the increasing of fluidized velocity at the same combustion condition.④When the amount of the fuel was stable, the more of oxygen content, the greater of burning-up degree of fuels, the concentration of CO decreased.⑤When the amount of the fuel was stable, with the oxygen content increased in the fluidizing air, the concentration of SO2 and NOX increased gradually, the concentration of NOX increased as the increasing of temperature of dense phase region.