Energy separation and CO2 nonequilibrium condensation effects in the pressure recovery process of hydrogen-rich fuel purification and decarburization

Abstract

Supersonic condensation separation is a potential environmentally friendly technology for hydrogen purification and CO2 capture. The nozzle plays a crucial role in achieving CO2 capture in practical applications. It requires specific pressure recovery abilities to deliver pre-purified hydrogen-rich fuel through downstream pipelines efficiently. However, excessive pressure recovery can quickly induce shock waves. Therefore, it is necessary to clarify the mechanisms involved in this process. This paper establishes a mathematical model for H2–CO2 mixture gas condensation. It examines the energy separation effect and the interaction mechanism of boundary layer/shock wave/CO2 phase change condensation in the pressure recovery process. The results indicate that the interaction between the boundary layer and shock wave is essential for inducing the energy separation effect. As pressure recovery increases, shock waves appear and move toward the throat, which hinders carbon capture. The maximum carbon capture efficiency decreases from 33.1% to 0%. Therefore, maintaining a pressure recovery efficiency between 33.3% and 50% is more conducive to considering nozzle pressure recovery and CO2 condensation separation.