下行床气固传质及反应特性的实验研究

Experimental Study on Characteristics of GasSolid Mass Transfer and Reaction in a Downer

以臭氧催化分解为模型反应,对气固并流下行循环流化床反应器中气固传质与反应特性进行了研究.制备了臭氧分解催化剂,并以它为循环物料在内径0.09m、高度8.2m的下行床中测定了颗粒浓度分布和臭氧浓度分布.实验结果表明,臭氧在加速段分解率在45%左右,约占总分解率的90%,其随颗粒循环量(Gs)的增加略有上升.当Gs从2.77kg/(m2-s)增加到6.58kg/(m2-s)时,全床分解率从50%上升至55%.建立了平推流的传质模型,给出了有效传质系数和操作参数的关联式.

Mass transfer and reaction characteristics in a gas-solid cocurrent down flow circulating fluidized bed （downer） are experimentally studied by catalytic decomposition of ozone. The profiles of solids and ozone concentrations are measured in a downer reactor with a diameter of 0.09 m and a height of 8.2 m while ozone decomposition catalyst is circulated in the bed. The experimental results show that about 45% of ozone is decomposed in the acceleration zone of the downer reactor which is more than 90% of total ozone decomposed in the downer. Ozone conversion rate in the downer increases from 50% to 55% when the solids circulating rate increases from 2.77 to 6.58 kg/（m^2·s）. A plug flow mass transfer model is established and correlation between effective mass transfer coefficient and operation parameter is obtained.