高低压脱乙烷塔系经济环境多目标优化

Multi-Objective Economic-Environmental Optimization of High and Low Pressure Deethanizer System

在双碳目标的背景下,传统化学工业需在经济效益与环境影响之间寻求平衡。高低压脱乙烷塔系作为典型的乙烯生产单元,进料组成多变,存在工艺参数及时调节、物料精准分离与高能耗冲突的问题。为解决此问题,提出了一种多目标优化框架,基于Aspen Plus平台构建双塔脱乙烷工艺模型,在限定包括产品品质约束、工艺最大允许操作范围的基础上,通过非支配排序遗传算法-Ⅱ(NSGA-Ⅱ)来获得环境与经济效益双目标的帕累托前沿,并进一步采用多目标决策分析准则优劣解距离法(TOPSIS)来获得帕累托前沿最优操作点。最后,使用单变量分析法研究了裂解反应温度、高低压脱乙烷系统进料预冷换热温度、低压塔塔釜热负荷、高压塔回流量对目标函数的影响。结果表明,与工厂实际操作条件相比,优化方案在牺牲税前利润0.91%的基础上,二氧化碳排放量减少了8.45%,有望同时实现经济效益和环境影响最佳的双目标。

Under the background of peaking carbon dioxide emissions and carbon neutral strategy,the traditional chemical industry needs to seek a trade-off between economic benefits and environmental impacts.As a typical ethylene production unit,the high and low pressure deethanization process has problems with variable feed composition,timely adjustment of process parameters,and conflicts between precise material separation and high energy consumption.To address this issue,a multi-objective optimization framework is proposed to achieve the optimum of the two objectives.First,based on the Aspen Plus platform,a process model for dual tower deethanization is constructed,and the Pareto frontier with dual objectives of environmental and economic benefits is obtained by the non-dominated sorting genetic algorithm II(NSGA-II)based on stipulations including product quality constraints and the maximum allowable operating range of the process.Furthermore,the TOPSIS(Technique for Order Preference by Similarity to an Ideal Solution)method of multi-objective decision analysis criterion is further used to obtain the optimal operating point on the Pareto frontier.Finally,univariate analysis is used to investigate the effects of heat exchanger temperature,tower kettle heat duty,cracking unit outlet temperature,and return flow rate on the objective function.Compared with actual plant operating conditions,the optimized plan reduces CO2 emissions by 8.45%at the expense of 0.91%of pre-tax profit,with the potential to achieve the best economic benefits and environmental impact.