固液相平衡级的通用算法

GENERALIZED ALGORITHM FOR SOLID-LIQUID EQUILIBRIUM STAGE

从热力学原理出发,建立了一种固液相平衡级计算的通用方法,通过自动判别平衡时的相数及析出固相的种类,经过较少的迭代次数就可获得固液相平衡时各相分率和组成,从而满足化工过程模拟计算与实际生产的需要。由于该解法为虚拟的等温蒸发过程,在判别平衡相数的同时给出了过程中晶体的析出顺序与各晶体刚析出时溶液组成,这些中间结果为分离过程的模拟计算提供了理论指导。此算法不仅完全不依赖于相图,而且还可通过对不同进料配比的计算,绘制出全范围内的固液相图。通过实例计算证明该方法可适用于目前文献中尚难以处理的复盐、含结晶水盐以及多离子体系。

This paper gives a general method to calculate solid and liquid equilibrium (SLE) stage by identifying the number of phases and the species of crystals existing at equilibrium automatically. An effective and rapid algorithm is proposed to obtain the result at equilibrium. Meanwhile this algorithm also gives the sequence of each crystal being precipitated and the composition of each phase at the time of crystal precipitation. This is important for the need of process simulation for solid - liquid separation. Especially, the method proposed does not depend on the phase diagram. On the contrary, the phase diagram of solid and liquid equilibrium could be obtained-by this method. Several examples are given to show that this method is capable of predicting the composition of SLE for systems with hydrate, multi -ion and complex salts.