In order to study the combustion performance of gangue with heat value less than 8.374 MJ/kg in the CFB boiler.The combustion process of coal gangue was investigated by modeling,and the burnout time and resident time of different particle size and varies kinds of coal waste were predicted.The maximum coal gangue particle diameters,bed inventory,pressure of primary air fan were obtained from the prediction.These results were applied in the design of a 220 t/h CFB boiler that purely fired the coal gangue.The 4 years operation proves that the design of the larger section size air distributor,low gas velocity in the riser,stronger momentum secondary air nozzle,higher collection efficiency cyclone,which are based on the model prediction,are reasonable.Coal gangue with heat value about 6.281 MJ/kg,the stable combustion as well as the loading ability achieve.It is found that the boiler could operate stably even with the coal gangue of low calorific value as 3.350 MJ/kg.The primary air pressure in the wind box is 11 kPa,and the bed temperature is 890 ℃ with the gas temperature of 910 ℃ at the inlet and outlet of the cyclone at rated load.The boiler operation thermal efficiency is 79.37％ due to the higher heat loss carried by the bottom ash and exhaust flue gas.The loss on ignition of both the bottom ash and fly ash are less than 3％.The emission concentration of SO2 and NOx are controlled very low and matches the local policy.The continuous running time is more than three months.%为了研究热值＜8.374 MJ/kg煤矸石的燃烧利用情况,模型研究了煤矸石的燃烧过程,预测了不同粒径和不同煤矸石的燃尽时间及停留时间,获得了入炉煤矸石的最大直径和相应的床存量、一次风机压头要求,并在220 t/h CFB锅炉设计中运用.4 a的运行实践表明,根据模型计算确定的采用大布风板、低流化速度、大动量二次风、高效分离器等是合理的,实现了热值约为6.281 MJ/kg煤矸石的稳定燃烧和锅炉带负荷能力,入炉煤矸石热值甚至降低至3.350 MJ/kg也能稳定运行.额定负荷下运行风室风压为11 kPa,床温为890 ℃,分离器进出口和返料温度均在910 ℃左右.锅炉实际热效率79.37％,主要的热损失是底渣和排烟损失.底渣和飞灰的烧失量均小于3％.SO2和NOx达到排放标准,连续运行时间超过3个月.
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