Modelling the three‐phase flow in a pilot‐scale airlift internal‐loop reactor for wastewater treatment

Abstract

The airlift internal‐loop reactor for wastewater treatment (AILRW) has an efficient performance due to the efficiently mixed flow of three phases: gas, liquid and solid. Basalt with density of 2760 kg.m^‐3 and diameter of 0.245 mm was used as carrier material and tested in a low range of solid fraction in the circulation (less than 4%). Three fractions (solid mass in the circulation zone W_c, solid mass in the settling zone at the top W_o and sediment mass at the bottom W_B) which contribute to the total loading solid mass W_t are estimated on experiments and described with dimensionless models. The presence of carrier material causes a non‐linear shift in the relationship between pressure difference at the bottom Dh_b and squared liquid velocity in the downcomer v_d ². However, no obvious influence of the loading of carrier on the gas holdup and oxygen transfer has been found in this study.

Keywords:

• airlift‐loop
• solid carrier distribution
• blocking
• three‐phase fractions
• oxygen transfer