Simultaneously enhancing H2 recovery and CO2 captured pressure during the hydrogen purification process of medium-temperature shifting gas by coupled wet CO2 separation-PSA technology: From laboratory to industrial scale test

Abstract

The petrochemical industry has a significant demand for high-purity hydrogen. It primarily obtained from the H₂ purification unit by using pressure swing adsorption (PSA) technology to recover H₂ from medium-temperature shifting gas (MTSG). The the coupled wet CO₂ separation-PSA process was introduced in this work, aiming to capture CO₂ from MTSG while simultaneously increasing the H₂ recovery rate. To enhance the desorption pressure of CO₂ separation unit in the coupled process to facilitate the storage or utilization of the captured CO₂, firstly, a rigorous thermodynamic study was carried out to provide a theoretical basis for the development of an improved CO₂ solvent. Subsequently, a pilot-scale test was executed to validate the theoretical findings. Finally, the patented coupled process was implemented at an industrial scale for the first time. The results showed that the capacity of PSA unit for H₂ purification increased from 6800 to 12,000 tons per year and the H₂ recovery rate increased from 84.6 % to 93.6 %; the CO₂ desorption pressure increased from about 0.03 MPa (traditional Benfield process) to 0.15 MPa, which reduced the energy consumption of CO₂ compression, and the total average annual economic benefits increased by US $ 15.55 million.