中文摘要：

针对管网升压事件讨论低温空分三塔精馏热耦合流程的变负荷操作模拟问题。分析认为,此大规模变负荷问题的求解难点在于耦合流程操作变量的微小变化引起了精馏塔浓度波形的大幅度移动,某些变量在微小步长上产生数量级的变化,基于牛顿法及其改进算法的数值计算方法在梯度计算中难以获得正确的下降方向,导致收敛困难。利用工况变量构造同伦参数并采用回溯同伦法（HBM）进行自动搜索,可以有效解决考虑耦合换热器换热面积计算的变负荷问题,能够描述因粗氩塔顶换热温差减小引起的＂氮塞＂现象,对过程控制更有指导意义。

英文摘要：

Load change problem synchronized with pipe network pressure increasing of three thermo-coupled columns in a cryogenic air separation unit was discussed.Due to the thermo-coupled features among the distillation columns,the simulation of the load change operation of a cryogenic air separation unit is difficult.Analytical results reveal that slight change of the operation variable can cause dramatic change of some other variables,which results in the difficulties of convergence due to inaccurate gradient approximation.The homotopy-based backtracking method（HBM）can efficiently deal with the load change simulation of the thermo-coupled system.The nitrogen block phenomena can also be simulated with this method.