超临界流体填料萃取塔流体力学和传质性能(Ⅱ) 传质性能

HYDRODYNAMICS AND MASS TRANSFER CHARACTERISTICS IN A SUPERCRITICAL FLUID EXTRACTION PACKED COLUMN (Ⅱ) MASS TRANSFER PERFORMANCE

根据双膜理论,建立了超临界流体填料萃取塔液相总体积传质系数关联式;依据柱塞流模型,应用超临界二氧化碳-异丙醇-水和超临界二氧化碳-乙醇-水2种实验体系在内径为25mm的塔内对金属板波和金属丝网θ环2种填料的传质性能进行了模拟计算。结果表明,本文提出的传质数学模型能较好地描述超临界流体填料萃取塔的传质性能。

A study on mass transfer performance was carried out in a continuous countercur-rent supercritical fluid extraction packed column of 25mm in diameter filled with structured packings and θ metal rings for the testing systems of carbon dioxide-isopropanol-water and carbon dioxide - ethanol-water under pressures from 8 to 15MPa and at 35 ℃. The experimental data under steady state were used to estimate the parameters of mass transfer,NOLP, HOLP and KOLa,with a plug-flow model. A model based on two film theory for calculating overall volumetric mass transfer coefficient was developed and the model parameters, A,m and n,were estimated by nonlinear programming Where A= 0.012, m = 0.65, n = 0. 30 for structured packings A = 0.015, m =0. 70, n = 0. 30 for θ metal rings