Research On Simulation Optimization And Control Of Styrene Distillation Process

Styrene is an important part of the chemical industry chain,and is one of the most basic monomers of polymer materials.It is widely used in construction,medicine,home appliances and other industries.Energy saving and consumption reduction in styrene production process has become an important means to improve product competitiveness,and the energy consumption in the production process is mainly concentrated in the distillation unit.As an energysaving distillation technology with high thermodynamic efficiency,the divided wall column can play an important role in styrene distillation unit.In this paper,the styrene distillation section of propylene oxide/styrene monomer(PO/SM)process is taken as the research object,and the divided wall column is used as the distillation energy saving technology to simulate and optimize the process.In this paper,four improved processes based on structures of the divided wall column is proposed,and the corresponding steady state mathematical models are established.The optimization problem of equipment parameters and operation parameters is abstracted into a mixed-integer nonlinear programming problem with minimum annual total cost as the objective function of optimization.An improved heuristic search algorithm based on chaotic sequence is proposed to search the economic optimal operating conditions for different wall distillation tower structures.Compared with the conventional distillation process,the annual total cost of Fully Thermally Coupled wall Column(FTC)process was reduced by 21.36%.The annual total cost of Agrawal’s liquid-only Transfer Divided Wall Column(ALT)process was reduced by 10.14%.In order to study the operability of different divided wall columns,a dynamic mathematical model was established for FTC and ALT with the best economic benefit and the second best economic benefit,and two control schemes were designed respectively.By introducing square error integral criterion,the robustness of several control schemes against disturbance is quantitatively compared,and the results show that the maneuverability of ALT is significantly better than FTC.