混合气流布置方式对循环流化床气固流动特性的影响

EFFECTS OF THE GAS-SOLID PHASE FLOW CHARACTERISTICS IN CIRCULATING FLUIDIZED BED AT DIFFERENT MIXING GAS DISPOSAL MODE

煤层气和煤矸石CFB混烧中,由于喷入的是可燃气体,燃烧所需的空气量及配风方式需要改变,必然会对炉内的气固流动特性产生影响。本文在煤层气和煤矸石某一混烧比下,确定所需的配风量和配风方式,通过改变混合气流的布置方式,对CFB炉内气固流动特性进行数值模拟。研究结果表明合理的布置方式可使炉内的气固混合较好,流动较稳定,且混合气流布置在两层二次风之间时,炉内密相区大部分颗粒速度较高,气固相间混合充分;密相区固体颗粒浓度较其它两种布置方式高,稀相区则相反,是比较合理的布置方式。研究结果对CFB混烧优化设计具有重要指导意义。

When the coal-bed gas and coal gangue were co-combusted in CFB, the air volume needed in the combustion process and gas distribution mode must be changed, and this change would work on the gas-solid flow behavior in the CFB. In this paper, by the thermodynamic calculation, the air volume and air distribution mode were confirmed firstly in a fix gas/gangue mixing rations, and then the numerical simulation of the gas-solid flow behavior were done when the disposal mode of the gas burner was changed. The results show that the appropriate disposal mode has a good effect on the gas-solid mixing and the flow behavior. When the mixing gas was disposed between the upper-layer and down-layer of second air, the particle velocity was higher in dense bed, and the gas-solid mixing was well-proportioned. Compared with the other two disposal mode, the particle concentration was higher in dense bed, and the particle concentration in dilute phase region was lower, it is a reasonable disposal mode. The result provided some guiding significance for the combustion optimization of coal-bed gas and coal gangue.