蒸馏塔板上汽液传质系数的确定——非平衡池法(Ⅰ)模型的建立及求解

本文提出一种确定蒸馏塔板上汽液传质系数的新方法——非平衡池法.该法将塔板沿液流方向分为适当数目的串联非平衡池,通过联立求解每一池各相的物料衡算、能量衡算、相平衡和传质传热速率方程,可从塔板入口组成得到出口组成.调整汽液传质系数使计算的出口组成与实测值相等,从而可确定出两相传质系数.方程组用混合牛顿法求解.

A Nonequilibrium-Cell Method for the Determination of the Mass-Transfer Coefficients on Distillation Trays ( I ) Mathematical Model and its Solution

A method for the determination oi the mass-transfer coefficients of vapor and liquid phases on the distillation trays-nonequilibrium-cell method is developed. In the model the tray is divided along the liquid flow direction into a number of cells, in each of which both vapor and liquid phases are assumed to be well mixed and the mass and heat transfer between these two nonequilibrium phases proceeds across the vapor/liquid interface. For each cell the mass and energy balance equations for each phase are connected by the mass and energy conservation relationships around the interface which is assumed to be in therrnodynamic equilibrium. For binary distillation, with given flow rates, compositions and temperatures at the inlet and outlet of tray, the model can be represented by (11×nce+ 2) independent equations with the same number of independent variables. The equations are solved to obtain the individual phase mass-transfer coefficient for both phases on each tray using the hybrid Newton method. The model can be used to determine the transfer coefficient-area products simultaneously for both phases on the basis of a single set of experimental data with both phase rate controlling system. On the other hand, the individual phase coefficients have to bo obtained separately with two sets of data each with one phase rate controlling system by the conventional "efficiency method (e. g. the AIChE model) (nce-number of cells per tray. )