三相循环流化床中的气液相界面积和传质系数

采用溶氧法测量了三相循环流化床中液相溶氧浓度的轴向分布,并按轴向扩散模型处理实验数据,优化得到气液体积传质系数kLa,同时用光纤探头测量了体系中的气含率和气泡大小分布,计算得到了气液相界面积a和气液传质系数kL,并研究了主要操作条件(表观气速、表观液速和固含率)对气液传质系数的影响规律.

Gas-Liquid Interfacial Area and Mass Transfer Coefficient in a Three-phase Circulating Fluidized Bed

The gas-liquid mass transfer behavior is studied in a three-phase circulating fluidized bed reactor with 140 mm inner diameter and 3.0 m height. Using the oxygen dissolution method, the volumetric mass transfer coefficient kLa is obtained from the measured bulk concentration in the liquid phase by fitting to the axial dispersion model. The gas holdup and the distribution of bubble size in the bed are measured by a fiber optical probe system, then the gas-liquid interfacial area a and the mass transfer coefficient kL are calculated. The influences of the main operation conditions, including superficial gas velocity, superficial liquid velocity and solid circulating rate, are systematically investigated.