Hydrogen recovery from Tehran refinery off-gas using pressure swing adsorption, gas absorption and membrane separation technologies: Simulation and economic evaluation

Abstract

Hydrogen recovery from Tehran refinery off-gas was studied using simulation of PSA (pressure swing adsorption), gas absorption processes and modeling as well as simulation of polymeric membrane process. Simulation of PSA process resulted in a product with purity of 0.994 and recovery of 0.789. In this process, mole fraction profiles of all components along the adsorption bed were investigated. Furthermore, the effect of adsorption pressure on hydrogen recovery and purity was examined. By simulation of one-stage membrane process using co-current model, a hydrogen purity of 0.983 and recovery of 0.95 were obtained for stage cut of 0.7. Also, flow rates and mole fractions were investigated both in permeate and retentate. Then, effects of pressure ratio and membrane area on product purity and recovery were studied. In the simulation of the gas absorption process, gasoline was used as a solvent and product with hydrogen purity of 0.95 and recovery of 0.942 was obtained. Also, the effects of solvent flow rate, absorption temperature, and pressure on product purity and recovery were studied. Finally, these three processes were compared economically. The results showed that the PSA process with total cost of US$ 1.29 per 1 kg recovered H2 is more economical than the other two processes (feed flow rate of 115.99 kmol/h with H2 purity of 72.4 mol%).