EFFECT OF THE EJECTOR CONFIGURATION ON THE GAS SUCTION RATE AND GAS HOLD-UP IN EJECTOR LOOP REACTORS

An experimental study has been aimed at examining the effect of ejecto r configuration on the rate and energy effectiveness of gas suction an d on the values of gas hold-up in ejector loop reactors. Experimental data showed that insertion of a swirl body into the ejector nozzle inc reased the suction rate and dispersion efficiency of the ejector distr ibutor and significantly improved its operating flexibility. In the ab sence 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 confi gurations without the mixing tube. The ejector suction efficiency incr eased 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 incr ease 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 mixin g tube length. Comparison of the energy effectiveness of gas suction i ndicated 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(0G)/epsilon(G) - u(0L)/(1 - epsilon(G)), for the slip velocity valu e u(s) = 0.224 m s(-1), proved adequacy of the slip velocity concept f or description of gas-liquid flow in ejector loop reactors. (C) 1997 E lsevier Science Ltd.