煤制天然气酚氨废水汽提过程经济和环境多目标优化

Multi-objective optimization of phenol-ammonia wastewater stripping process in SNG plant

迫于环境影响和法律条约的双重压力,传统的化学工业开始寻求在过程设计阶段综合考虑经济、环境和社会可持续性等多目标最优。以煤制天然气企业中的脱酸脱氨汽提工段为案例,首先对比了单塔侧线加压和双塔加压工艺,结果显示单塔工艺更加经济但对环境的可持续性危害更高。在此基础上,选取了塔板总数、侧线位置和热进料温度三组决策变量,并以年度总费用和潜在环境影响指数最小为目标函数,对整个单塔侧线工艺进行了多目标优化。优化结果表明在保证产品质量的前提下,通过操作条件的改变有实现经济成本和环境性能同时最佳的潜力。

Increasing twins pressure of environmental and legislation have resulted in changing the approach of traditional design to consider the multi-objective sustainable design in chemical processes. This paper focuses on the phenol-ammonia wastewater stripping section in a coal to synthetic natural gas （SNG） plant. Comparison between the single pressurized tower with side-draw design and double pressurized tower design shows the first design benefits from lower economic cost at the expense of low sustainability. On such basis, three key decision variables are selected, including total number of stages, side-draw position and heat feed stream temperature to minimize the total annualized cost （TAC） and potential environment impact （PEI） metric. The optimal solution reveals that the single pressurized tower with side-draw design has potential to achieve low economic costs and high environmental performance simultaneously by changing the operating conditions.