含内构件的循环流化床的动态压力特性

Characteristics of dynamic pressure in circulating fluidized bed with internals

针对含内构件的循环流化床,以石英砂为物料,使用动态压力传感器测量了含内构件的流化床中气固两相流的动态压力,分析了床内的瞬时压力特性.结果表明,在进出口总压降中,文丘里压降最大,占主床压降的60%以上.表观气速和固体颗粒循环流率共同影响循环流化床内的压力特性.压力瞬时波动功率谱分析表明,压力波动对应一个主频,表观气速越小、颗粒循环流率越大时,压力波动越大,且循环流化床底部压力波动比上部大.加入内构件能有效引导气流,使流动更均匀.

The circulating fluidized reactor is applied widely in desulfurization and denitriding due to high gas-solid contact efficiency.And in order to enhance the effect of mass transfer in solid-gas phase,an internal was installed in the cold circulating fluidized bed (CFB)platform,and the pressure character under different conditions was studied.To investigate the characteristics of pressure fluctuations in circulating fluidized bed,the dynamic pressure of gas solid two-phase flow in circulating fluidized bed riser were systematically measured with quartz sand in it by the dynamic pressure sensors.The results showed that when a complex internal was installed in the CFB,the line of system pressure distribution matches the theory of the pressure balance and presents a shape of "8".The main bed drop includes the inlet pressure drop,the venturi pressure drop,the riser pressure drop and the outlet pressure drop.The venturi pressure drops occupied the major part with a percentage of exceeding 60%.The superficial gas velocity and the particle circulating flow rate affected the main bed pressure drop simultaneously.The inlet pressure drop increased with the increase of the superficial gas velocity,while hardly being affected by the particle circulating flow rate.The venturi pressure drop changed similarly with the main bed pressure drop.The outlet pressure drop increasesd slightly with the increase of the superficial gas velocity,while hardly being affected by the particle circulating flow rate.The power spectrum analysis of the transient pressure of the circulating fluidized bed showed that the pressure fluctuation had a corresponding dominant frequency which had the corresponding size of vibrational energy.The smaller the superficial gas velocity was,the larger the particle circulating flow rate was,and the pressure fluctuation would be bigger.The system pressure drop increased with the increase of the height of the particle in the pipe.And the component could increase the pressure in the circulating fluidized bed and also reduced the non-uniform degree of the pressure while optimizing the flowing field.