Design and numerical investigation of ejector for gas pressurization

Abstract

AbstractCompared with the compressor, the ejector is a novel cost‐effective device to pressurize gas. Taking the regeneration natural gas pressurization process in the molecular sieve dehydration system as an example, it is first proposed to replace the compressor with an ejector to accomplish the pressurized recovery of low‐pressure regeneration natural gas. The numerical simulation method has been validated, and its results agree well with published experimental results. The simulation results indicate that the ejector designed with one‐dimensional theory can achieve the low‐pressure gas pressurization. Besides, the influence of operating parameters and structural parameters on the ejector performance is also investigated. As the discharged pressure increases, the entrainment ratio gradually decreases, but the pressure ratio rises linearly. With the increase of the induced flow pressure, the ejector pressurization range reduces. Under different discharged pressure, the entrainment ratio presents three different trends when the primary flow pressure enhances. Also, a larger nozzle exit diameter will cause the shock wave phenomenon, which is not conducive to the ejector performance, so there is an optimal nozzle exit diameter for the ejector. The length of the constant‐area mixing chamber has seldom effect on the pressure ratio. The optimal value of the NXP for entrainment ratio is equal to (0.5–1.0)d2. In conclusion, the research provides a new gas pressurization approach and a much better understanding of the gas flow and mixing process within the ejector.