Optimization of two-phase ejector geometry used in flare gas recovery employing multi-objective genetic algorithm

Abstract

Flare gas recovery is a procedure that reduces the greenhouse gas emissions. Ejectors play a technically efficient and productive role in the recovery of flare gas. The higher the secondary fluid entrainment rate causes better performance of the ejector. The main purpose of the recent study is increasing the flow of gas in the gas recovery ejectors. A two-phase ejector is examined using computational fluid dynamics (CFD) in order to have an optimized performance. The diameter and length of the throat, the nozzle diameter, as well as the converging and diverging angles are the geometrically assigned influence the secondary fluid flux. To achieve the highest entrainment rate, the optimal value of these parameters was determined using the multi-objective genetic algorithm (MOGA) proposed three points as an ejector design candidate. As a result, the rate is improved when a reduction occurred in the length of the throat and the converging angle. It was also increased while reducing the nozzle and throat diameters and the diverging angle. Compared to the basic case, the optimal geometries raised the amount of flow by 25.5, 16.06, and 12.76 times, respectively. Energy efficiency evaluation for the base model and all design points has been made was about 3.5 times higher than the basic case in the second candidate. The first point could also improve the efficiency up to 78%, whereas it was dramatically reduced by the third candidate (47%).