Feasibility analysis and simulation of argon recovery in low oxygen-purity cryogenic air separation process with low energy consumption

Abstract

This paper has discussed and simulated different low oxygen-purity air separation processes with or without argon recovery to find out efficient air separation process using HYSYS platform, and proposed a novel mixing-column process that provides high argon recovery rate based on energy saving effect. For comparison, all the proposed cases are simulated under the same process conditions of 50,000 Nm3/h feed air, 95% gaseous oxygen purity, 0.03 MPa gauge pressure, and 300 Nm3/h liquid oxygen output. Three main performance parameters including oxygen recovery rate, energy consumption and argon recovery rate are compared, and the simulation results show that among five types of processes without argon recovery, the triple-column process, whose energy requirement decreases by 14.9% compared with conventional dual-column process, achieves the lowest energy consumption. Argon production is required in many aspects during air separation process. The feasibility of argon recovery in low oxygen-purity air separation process is studied. The process with argon recovery named mixing-column process is proposed, whose argon recovery rate can reach up to 60.88%, which further increases up to 62.23% with the optimized raw argon flow rate and mixing-ingredient. The energy consumption of the proposed mixing-column process is decreased by 3.5% compared with conventional dual-column process, while the argon recovery rate of the triple-column process can only reach to 4.55% in despite of energy saving by 12%. In addition, more stable argon recovery performance as well as higher argon recovery rate is realized by this novel process when using varied oxygen purity in low oxygen-purity (≤99%) process.