Multi-objective optimization of NH3 and CO2 separation with ionic liquid process

Abstract

Abstract Melamine production produces tail gas with a significant amount of both NH 3 and CO 2 . Benefiting from the development of green solvents, using ionic liquids instead of traditional solvents as water for NH 3 and CO 2 separation has attracted wide attention. Multi-objective optimization (MOO) is employed to optimize the ionic liquid-based process in this work. In order to decrease the energy consumption in the ionic liquid based separation process, a MOO research was carried out using Aspen Plus and Matlab software in this work. In this work, one ionic liquid-based process was simulated and optimized by the nondominated sorting genetic algorithm II (NSGA-II) algorithm. The minimum total separation cost (TSC) and total process CO 2 emission (TPCOE) were set as two objective functions. With the constraints and several operational parameters optimized, the Pareto front displays a set of nondominated, optimal design parameters that satisfy the specification of the NH 3 concentration standard in outlet gas. The results show that the effect of desorption pressure and the ratio of lean solvent to total solvent are critical for both TSC and TPCOE. After the MOO, the TSC of the ionic liquid process can be decreased by 5%, and TPCOE is reduced by 12% compared with the base case. The optimization results support the optimal design and operation of the NH 3 and CO 2 separation process with ionic liquids considering environmental and economic objectives.