Experimental study on combustion characteristics of extremely low calorific solid wastes in a fluidized bed combustor

Abstract

With the rapid development of economy in China, the demand for energy is increasing day by day. In order to relieve the energy crisis and lessen environmental pollution, many low calorific solid wastes are required to dispose and recover heat in an efficient and clean way. This paper selected three representative extremely low calorific solid wastes: coal gangue (Qar,net = 4600 kJ/kg) generated from the coal preparation process, oil shale (OS) semi-coke (Qar,net = 2384 kJ/kg) produced from the refinement of OS, and small-size OS (Qar,net = 3530 kJ/kg) whose particle size was below 3 mm. The systematic research of experiments and computational analyses was carried out on a bench-scale fluidized bed combustor and a pilot-scale fluidized bed combustor, respectively, to investigate combustion characteristics in the fluidized bed and engineering applications. The experimental results showed solid wastes within the scope of such calorific value could be burnt steadily in the fluidized bed, and the key to large-scale engineering application was to improve combustion intensity in the furnace as far as possible and reduce pollutant emissions. Based on detailed experiments, different engineering application solutions were put forward in this paper, depending on characteristics of three low calorific fuels mentioned above.