Gas hold-up and liquid velocity in a two-dimensional air lift reactor

Abstract

Gas hold-up and liquid circulation velocity were studied in a two-dimensional air lift reactor. A comparison was made between bubble column and air lift operation. Four different gas spargers were studied, and several different gases: He, CO 2, Ar, air and Freon 114. No influence on the measured variables could be attributed to gas distribution. The nature of the gas had a strong influence in the case of bubble column operation. Helium does not exhibit the maximum in the hold-up which is characteristic of the “transition regime”, and in general gives lower values. In air lift operation, the differences due to the nature of the gases are much smaller, and can be neglected. The liquid recirculation velocity depends on the gas superficial velocity, J G, raised to the power 0.4. This concurs with published data obtained in large air lift devices. It is concluded that a two-dimensional air lift can be used for research and development, since it present the same basic fluid—dynamic characteristics as large air lift reactors. In addition, the two-dimensional device allows the examination of flow patterns and configuration, which are decisive in design and scale-up of this type of reactor.