(104b) Effects of Gas Jet in the Downcomer On Liquid Circulation in Internal Loop Airlift Reactors

In recent years, internal loop airlift reactors (ILAR) is widely used in petrochemical, biochemical and energy processes due to its simple mechanical design, effective interphase contact and efficient slurry circulation. However, the liquid velocity in ILAR is limited because the liquid circulation is driven by the density differences of flow in riser and downcomer, which in turn imposes a limitation on the gas velocity and the reactor yield, thus hinders the broader application of ILAR. To solve this problem and increase the yield of ILAR, the present paper provides a promising method by designing a gas jet in the downcomer of ILAR to promote the liquid circulation, which allows the reactor to operate with higher superficial gas velocity, and thus increases the yield of ILAR. In addition, computational Fluid Dynamics (CFD) three-dimensional modeling is employed to investigate the influences of key parameters of jet (such as size, angle, location and flowrate etc.) on the hydrodynamics in ILAR involving liquid circulation, and to determine the optimal configure and design of gas jet. The results are validated by the cold model experiments conducted in an industrial-scale ILAR. It is shown that with optimal design, the liquid velocity is improved by 20% by using only 2% of total inlet gas to inject into the downcomer, and the yield is increased by 5% at a high superficial gas velocity (ug=0.4m/s ).