Synergistic technology of liquid nitrogen condensation integrated with pressure swing adsorption for CH4/VOCs recovery: modeling, experiment, and optimization

A synergistic technology combining liquid nitrogen (LN 2 ) condensation with pressure swing adsorption (PSA) technology was proposed, which the LN 2 condensation section utilizes the cooling energy of LN 2 to recover high-value recycled oil, while the PSA section concentrates CH 4 that is difficult to condense, demonstrating exceptional oil vapor recovery capability. • A “LN 2 condensation-adsorption” synergistic system for CH 4 /VOCs recovery was proposed. • The multi-component has a certain promotion effect on the recovery of light hydrocarbons. • LN 2 condensation recovery technology has excellent carbon reduction capability. • The PSA system effectively increased CH 4 concentration. • The integrated system demonstrates significant advantages in controlling oil vapor emissions. The increase in volatile organic compounds (VOCs) emissions poses an urgent environmental challenge, and methane (CH 4 ) treatment can effectively slow down the greenhouse effect. In order to meet the increasingly stringent emission standards on petroleum and petrochemical industry, this paper proposes an integrated CH 4 /VOCs recovery technology that combines liquid nitrogen (LN 2 ) condensation technology and pressure swing adsorption (PSA) technology. The system was simulated by Aspen HYSYS and Aspen Adsorption and the recovery law of light hydrocarbons was studied through experiments. The performance of the LN 2 condensation model was also evaluated on the condition of crude oil storage tanks. Under the optimized operating conditions (gas inlet flow of 600 m 3 /h, inlet total hydrocarbon concentration of 3.5 %, and condensation temperature of −160℃), the LN 2 condensation system performed better, with an economic efficiency ratio of 2.3, energy utilization efficiency of 94.5 %, and non-CH 4 hydrocarbon recovery rate of 99.6 %. By analyzing the adsorption performance of the adsorption tower for CH 4 , the breakthrough time was determined to be 500 s. During the PSA process, the flow rate of the recovered gas decreased from 8.43 kmol/h to 3.48 kmol/h, and the mole fraction of CH 4 increased from 0.2 to 0.53 with a recovery rate of 96.11 %, indicating that the initial enrichment of CH 4 was successful. In conclusion, this integrated technology provides a viable solution for efficient emission reduction in crude oil storage tanks.