Effect of gas liquid separator and liquid height on the global hydrodynamic parameters of an external loop airlift contactor

This study is devoted to the measurement of global hydrodynamic characteristics (gas hold-up and liquid circulating velocity) of an external loop airlift contactor filled with tap water, with different conditions for phase separation and for liquid height. It is shown that these two operating parameters have a great influence on the behaviout of the airlift reactor. These parameters generally are not specified for the use of the relations proposed in the literature, despite their importance. However, this study reveals that two openings in the top junction between the riser and the downcomer are able to generate doubling of the liquid circulation velocity and a decrease in the gas hold-up of about 30% for high gas throughputs. Furthermore, under these conditions, the liquid circulation velocity is multiplied by a factor of 2.7 with little change in the liquid height before aeration, and the gas hold-up is decreased about 27%. 0 1997 Elsevier Science S.A.