A side stream is recycled to the external feed stream of the column through an equilibrator as an internal feed stream . the simulation results indicate effects on the characteristics of cryogenic distillation column . consideration is given to the behavior and characteristics of the set of ordinary differential equations 3 、分析了浓度极稀物系动态精馏模型的特点,建立了此类物系动态模型的求解策略,通过对模型中状态变量的转换,使原本刚性较强的微分方程组转化为一非刚性的常微分方程组。