Experimental Study on Characteristics of Gas-Solid Mass Transfer and Reaction in a Downer
下行床气固传质及反应特性的实验研究

Mass transfer and reaction characteristics in a gassolid 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/(m2s). A plug flow mass transfer model is established and correlation between effective mass transfer coefficient and operation parameter is obtained.