两级分离返料循环流化床的冷态试验

Cold state experiment on two-stage separation return circulating fluidized bed

针对循环流化床煤气化装置在工程实际运行过程中出现返料回路受炉膛压力波动而出现气固分离效率下降、返料不畅的问题,使用两级分离返料循环流化床装置进行冷态试验,研究不同床料粒径分布、一级分离器入口固气质量比、一级分离器入口气速对一级分离器分离效率和二级返料器压力波动的影响规律。结果表明:入口固气质量比从3.5增大至6.2,一级分离器分离效率从90.78%增大至94.12%,二级返料回路受炉膛压力波动影响小,压降标准差维持在0.044 kPa左右;入口风速从8 m/s增大至15 m/s,一级分离器分离效率从92.06%增大至95.20%;运行床料中位粒径从499.9μm减小到78.1μm,系统分离效率维持在大于99.98%的前提下,一级分离器分离效率从97.02%减小87.06%;运行床料中位粒径小于107.3μm时,二级回路Geldart C类颗粒体积分数大于35.56%,二级立管内物料流化较差,包含较多的细床料,影响系统稳定运行。

In view of the problems that decrease in the gas-solid separation efficiency and poor reture of the material in the return loop of the circulating fluidized bed coal gasification unit caused by the fluctuation of furnace pressure,cold state test was carried out on the two-stage separation and return material circulating fluidized bed device.The effects of different bed material particle size distribution,solid-gas ratio at the inlet of the first stage separator,and gas velocity at the inlet of the first stage separator on the separation efficiency of primary separator and the pressure fluctuation of the secondary loop seals were studied.The results show that as the inlet solid-gas ratio increases from 3.5 to 6.2,and the separation efficiency of the primary separator increases from 90.78%to 94.12%.The secondary loop seals is less affected by the furnace pressure fluctuation,and the standard deviation of the pressure drop is maintained at about 0.044 kPa.As the inlet gas velocity increases from 8 m/s to 15 m/s,the separation efficiency of the first-stage separator increases from 92.06%to 95.20%.As the operation the median particle size of the bed material decreases from 499.9μm to 78.1μm,and the separation efficiency of the system is maintained at greater than 99.98%,the separation efficiency of the primary separator is reduced from 97.02%by 87.06%.The median particle size of the bed material is less than 107.3μm,and the volume fraction of Geldart C particles in the secondary loop selas is greater than 35.56%,the fluidization of the material in the secondary riser is poor,carrying more fine bed material,which affects the stable operation of the system.