Effect of the ejector configuration on the gas suction rate and gas hold-up in ejector loop reactors

Abstract

An experimental study has been aimed at examining the effect of ejector configuration on the rate and energy effectiveness of gas suction and on the values of gas hold-up in ejector loop reactors. Experimental data showed that insertion of a swirl body into the ejector nozzle increased the suction rate and dispersion efficiency of the ejector distributor and significantly improved its operating flexibility. In the absence of swirl elements, the gas suction rate increased slightly with the mixing tube length up to the length-to-diameter ratio equal to six. In the presence of swirls, however, the mixing tube length exhibited negative effect on the ejector performance and the highest values of gas suction rate and dispersion efficiency were observed for the configurations without the mixing tube. The ejector suction efficiency increased sharply with increasing swirl number Sw b (related to the swirl body parameters) in the region of its values 0.06–0.12 while the increase of Sw b above 0.2 resulted in a decrease of the gas suction rate. For Sw b = 0.12–0.20, the gas suction rate was significantly higher than that achieved in the absence of swirls even at the optimum mixing bube length. Comparison of the energy effectiveness of gas suction indicated superiority of the single-orifice nozzles with swirl inserts over the other tested variants. Good agreement of gas holdup data from all experimental runs with values calculated from the relation u s = u oG ge G − u oL (1−ϵ G) , for the slip velocity value u s = 0.224 m s −1, proved adequacy of the slip velocity concept for description of gas-liquid flow in ejector loop reactors.