Distillation is a very important process in the large-scale production of ethylene and other refining and petrochemical processes.Based on the rigorous model of MESH and SRK equation of state

the optimization strategy for the operation of distillation column was studied.Since the open form equation-based model of distillation column has relatively small degrees of freedom

special structure and strong sparsity

a method based on the reduced sequential quadratic programming(SQP) algorithm and hybrid derivative method was presented to solve this kind of problems.The first order gradient information was obtained by the analytical method and preconditioned automatic differentiation.Because the objective was simple and relate to small number of variables

the analytical gradient function was obtained to get gradient information of objective.To utilize the sparsity and structure of the distillation column model

the sparse structure and compress pattern were obtained firstly by preconditioning procedures

and then gradient information of constraints was obtained through preconditioned automatic differentiation technology at each iteration.Computing results demonstrated that the proposed method was more efficient than the standard SQP algorithm

and the economic benefit could be improved significantly with optimal operation obtained under different conditions.