汽液相平衡中无模型法的计算及应用

Calculation and application of model-free methods in vapor-liquid phase equilibrium

汽液相平衡计算是化工过程开发及优化设计的基础。汽液相平衡计算的核心是确定体系处于平衡状态时,温度T、压力p、液相组成x及汽相组成y 4个变量之间的关系。在这4个变量中,汽相组成一般难以准确测定,低浓度汽相组成的测定偏差更为明显,因此一般实验测定T、p、x,用热力学方法推算y。由T、p、x数据推算y的方法分为模型法和无模型法两种,无模型法由于不需要考虑各种活度系数模型的使用限制条件而备受国内外学者的关注。通过分析无模型法的原理,按照直接法和间接法两部分对目前无模型法的发展历程进行归纳综述,着重比较了各方法的适用体系、收敛速度和计算精度等方面,总结了几种常用方法的应用情况,并对无模型法未来的研究方向进行了展望。

Calculation of vapor-liquid phase equilibrium was the foundation for development and design optimization of chemical processes. Focal point of the calculation was to determine relationship between four variables of temperature T, pressure p, liquid phase composition x and vapor phase composition y in any vapor-liquid phase equilibrium system. Among these four variables, it was difficult to accurately measure vapor phase composition y, especially at low vapor concentration. Therefore, y was generally calculated by thermodynamic methods after experimental determination of p, T and x. Such methods could be divided into model and model-free methods, which model-free methods got academic attractions as a result of no need to consider application limitations of various activity coefficient models. Through analysis of principles of model-free methods, recent progress with an emphasis on applicable system, convergence rate and calculation accuracy was summarized and compared from the viewpoint of direct and indirect technique. The application of several common methods was discussed and the future research of model-free methods was forecasted.