Three-Dimensional Investigation of Gas Holdup Changes as a Very Effective Hydrodynamic Parameter in Airlift Reactors

Abstract

In this study, hydrodynamics, liquid velocity distribution, flow regime, and gas holdup were modeled and simulated in air-stirred reactors such as bubble column, airlift, and net draft tube airlift reactors according to the computational fluid dynamics, while the inner space of the reactors was filled with water or diesel by injecting air through the air distributor from the bottom of the reactor.  The present study investigates the three-dimensional changes in gas holdup as a very effective hydrodynamic parameter in airlift reactors. The results and data of this study, which includes thirty-six simulations for the water-air system and the diesel-air system, showed good consistency and agreement with the laboratory data, so the mean error in all these simulations was about 14%. Reactors containing diesel liquid fluid showed different behavior in different superficial gas velocities and different geometries in comparison with reactors containing water. In addition, airlift reactors with a net draft tube were simulated with very high precision in design. They showed that the gas holdup is higher than the simple airlift reactor despite the more complex structure. They also provide better mixing and more optimal fluid distribution than the bubble column reactor throughout the process execution environment.