用单纯形法同时确定轴向混合系数与传质系数

在内径5cm的梯形波空气脉冲柱内,测定了30%TBP(煤油)-Th(NO_3)_4-HNO_3(H_2O)体系在两种板段结构条件下钍的浓度剖面.用扩散模型描述萃取过程,用单纯形法直接由浓度剖面同时确定轴向混合系数、传质系数与真实传质单元高度.由此获得的计算的浓度剖面与实验测定的浓度剖面比较符合.结果表明:梯形波脉冲柱的轴向混合系数较小,用于补偿轴向混合的柱高约占表观传质单元高度的32—44%;用单纯形法寻优,对原始微分方程采用差分近似得两组线性代数方程组,对每组线性代数方程组用追赶法直接解,两组方程之间用迭代法,程序简单,收敛较快.在PDP11/23小型计算机上,约1分钟即算得一组结果.

Simultaneous Determination of Axial Dispersion and Mass Transfer Coefficients Using a Simplex Method

In investigating the performance of an extraction column in which axial concentration profiles were measured, a simplex method has been proposed for the simultaneous determination of axial dispersion and mass transfer coefficients from steady state data. The axial concentration at any point in continuous flow equipment is dependent on both the rate of material transfer and degree of dispersion. Consequently, parameters representing these effects should be obtainable by fitting the solution of a characteristic model equation to the experimentally determined cincentration profiles. In an extraction column of 5 cm inner diameter with a trapezoidal pulse, concentration profiles of Th in two phases (30% TBP (OK) and Th(NO3)4-HNO3-H2O) and two plate cartridges were measured. The diffusionmode] equation is used to describe the mass transfer process, and computed values obtained agree with experimental steady state profile data satisfactorily . Results show that axial dispersion coefficients of a trapfzoidal pulse column are smaller than those of a sine pulse, and that the column height for compensating axial dispersion is 32-44% of the apparent transfer unit height. When the simplex method is used for optimization, the approximation of the original differentia] equations with difference equations leads to linear systems of equations. The elimination method is used to solve directly each system (x or y) of equations, and the iterative method is used to solve a system (x and y) of equations. The program is very simple, the conver gence fast.Calculating a data set takes about 1 mm a minicomputer PDF 11/23.