Problems in calculating the ejection coefficient of ejectors in natural gas liquefaction cycles

This article examines the relevance of using ejectors in small- and medium-capacity natural gas liquefaction cycles, as they offer a lower-cost and more reliable alternative to turboexpanders. It is emphasized that the main difficulty in their design stems from the fact that traditional calculation methods, such as those of E. Ya. Sokolov and N. M. Singer, are not adapted for working with multicomponent, often two-phase (vapor-liquid) natural gas flows.

The study calculates the ejection coefficient using the method of E. Ya. Sokolov and N. M. Singer, as well as using the Caltec Surface Jet Pump Unit and Ejector Extension v3.0.2 software modules. The obtained calculated values are compared with experimental data obtained at an operating liquefaction plant in the village of Razvilka.

The analysis reveals significant discrepancies (from 28% to 69%) between all calculation models and actual results. Conclusions are drawn regarding the applicability of standard ejector calculation methods, and the main reasons for discrepancies with experimental data are identified. The primary cause of these discrepancies is identified as the lack of consideration of phase transitions (condensation) in the mixing chamber and the thermodynamic properties of the multicomponent mixture in the models. A conclusion is drawn regarding the need to develop a new, adapted calculation method.