棉秆在循环流化床中燃烧特性的实验研究

Experimental Study on Cotton Stalk Combustion in Circulating Fluidized Bed

该文介绍了长度为10—100mm棉秆与弱酸性床料的混合流化特性，主要研究流化风速和棉秆与床料不同配比对混合均匀度的影响。实验结果表明，10—100mm棉秆与一定粒径分布的床料，质量配比为1-2％，流化数N〉3时，能较均匀地混合流化，但流化数N〉7时，混合均匀度有所降低。棉秆与床料配比对混合均匀度也有影响，棉秆的质量配比越小，混合得越均匀，所以设计循环流化床锅炉时流化风速、静止床高要选择合理。在0．5MWCFB实验装置上研究了纯棉秆燃烧时，流化速度、二次风率和棉秆给料量对炉内温度场分布的影响，结果表明，根据CFB实际运行参数，当流化速度为4-4．5m／s时，尽管此时混合均匀度有所降低，但并没有影响到密相区稳定燃烧，其温度能够维持在830-870℃。实验后放出的底渣没有出现烧结现象，基本保持原来的形貌，说明弱酸性床料能够适合棉秆循环流化床燃烧。

This paper reported the mixing characteristics of binary mixture of cotton stalk with 10-100 mm length and alternative bed material in a fluidized bed. Experiments on a cold test facility showed that pure cotton stalk can not be fluidized, and adding bed material can improve the fluidization condition. Effects of gas velocity and mass percentage of cotton stalk on mixing characteristics were investigated. Cotton stalk can mix well with bed material at fluidization number 3-7. The minimum fluidizing velocity of the binary mixture of cotton stalk and bed material can be obtained by experiments. The study concerning the temperature profile was performed on a circulating fluidized bed （CFB） test facility with a heat input of 0.5 MW. Effects of fluidizing velocity, secondary-air ratio and cotton stalk feed rate on the temperature profiles in boiler furnace were examined. According to the experimental results, when the fluidizing velocity is up to 4.5 m/s cotton stalk can still be burned stably in the dense bed. Alternative bed material is difficult to react with alkali metals from cotton stalk ash after combustion about 12 h. It conclude that alternative bed material is favorable for use in CFB during cotton stalk combustion.