木屑-石英砂喷动流化床内流动特性研究

为了开发喷动流化床生物质裂解反应器，建立了一内径为150mm的有机玻璃冷模实验装置，在室温下进行了生物质(木屑)和石英砂混合物在喷动流化床内的流动特性研究。考察了木屑、木屑与石英砂混合物的喷动流化现象。结果发现在喷动流化床其它条件相同时，床层中相同的木屑量，随石英砂量的增加，木屑的循环量减少；而相同的石英砂量，随木屑量的增加，石英砂的循环量增加。最小流化速度实验值与计算值相比略小但相差不大，可用Ergun公式预测床层的最小流化速度，但不能用Muthur公式来预测最小喷动速度，这是由木屑与石英砂颗粒混合物的性质和床层结构特性决定的。随着喷动气速和流化气速的改变，可观察到床内粒子表现出八种不同的流动状态：固定床区、流化床区、局部喷动床区、流化一局部喷动床区、喷动床区、喷动流化床区、喷动垂直输送区、喷动流化垂直输送区。

Flow Characteristics of Mixture of Quartz Sand -Sawdust in a Spout-Fluidized Bed With a Draft Tube

In order to develop a spout-fluidized bed reactor applied in pyrolysis of biomass, a cool model contactor (=150 mm) made of plexiglass is installed in which part of the research work is carried out to study the flow characteristics of the quartz sand -sawdust mixture. An experiment is made on spouting fluidization of sawdust or the quartz sand -sawdust mixture. The conclusion is that in the contactor bed, as the amount of quartz sand increases the amount of sawdust remains constant, the recycling amount of sawdust reduces, in case that the amount of quartz sand remains constant, the recycling amount of it increases with more sawdust in the contactor. The experiment minimum fluidized velocity is smaller than that calculated but the gap is narrow, it can be predicted with Ergun formula. But the minimum spouted velocity cannot be predicted with Muthur formula. The above phenomena are determined by the physical properties of the mixture itself and the constructer characteristics of the contactor. With the change in spouting gas rate and fluidizing gas rate, 8 flow states of the particles in the bed can be observed as of fixed bed, fluidized bed, local spouted bed, fluidized-local spouted bed, spouted bed, spout-fluidized bed, vertical spouted transport and spout-fluidized transport bed.