基于超熵产生分析的反应精馏系统多稳态研究(Ⅱ)稳定性分析

Multiple Steady States Analysis of Reactive Distillation Process by Excess-Entropy Production (Ⅱ)Analysis of the Stability

以环氧乙烷与水合成乙二醇为模型体系进行了实例分析,得到了该反应精馏系统在一定条件下的多定态解,利用超熵产生判据式对各定态解的稳定性进行了分析,在此基础上进一步讨论了多稳态产生的原因。结果表明:浓度涨落、温度涨落、其他操作负荷的变化以及反应动力学特性都可以成为反应精馏系统出现多稳态的原因。将超熵产生判据用于反应精馏体系定态稳定性的判定,较为可靠。因为超熵产生判据式是由热力学基本原理推导而来,较好地反映了反应精馏过程演化的非线性不可逆的热力学本质,因此本方法对反应精馏系统稳定性的研究,具有普遍的理论指导意义。

Using the synthesis of ethylene glycol （EG） from ethylene oxide and water by reactive distillation process as an example, the multiple steady states solutions of the reactive distillation process under definite conditions was obtained. The stability of these solutions was investigated by using the criterion of excess-entropy production, and the causes for the occurrence of multiple steady states were further discussed. The results show that the multiple steady states can be caused by many causes, such as the fluctuation of concentration and temperature, other operation load changing and the characteristic of kinetics. Since the stability criterion of excess-entropy production was deduced from the basic theory of thermodynamics, it accurately reflects the essence of the nonlinearity and irreversibility of the evolvement of the reactive distillation process. Therefore this criterion is accurate enough to be used for the stability evaluation of the multiple steady states solutions obtained above, and it can also be used to analyze the stability of reactive distillation processes other than the EG synthesis process.