(421g) Effect of Distributor Design on Gas Holdup for Slurry Bubble Column

Bubble columns are widely used for contacting gas–liquid and gas–liquid–solid mass transfer/chemical reactions. Gas distributor is the most important accessory because it decides the bubble size/rise velocity and gas distribution. These in turn govern the axial hold-up profiles, the liquid phase flow pattern and hence the performance of bubble columns. In this study we focused on the effect of distributor design, height to diameter ratio, solid concentration, and superficial gas velocity on overall gas holdup. The overall gas holdup, was studied experimentally using a rectangular slurry bubble column (7x10x200cm) operating at ambient temperature and pressure filled with paraffin liquid (c₁₀-c₁₃) to three different heights L/D (6,7.5 and 10) containing varying volume fraction(0%,9% and25%) of silica as a solid phase . The gas phase was oxygen which was inter the column through the distributor with varied superficial velocity(0.7,1.5,3,4,6 cm/sec) spanning both the homogeneous and churn-turbulent flow regimes , two types of distributor used perforated plate with 56 holes of 1mm diameter and ring type distributor with 29 hole of 1.5 mm diameter .The results have shown that the overall gas holdup increased by increasing gas velocity and decreased by increasing L/D and silica concentration .Also, we found that the perforated plate distributor gave higher gas hold up than ring distributor at gas velocity >3cm/sec. The following correlations was obtained: For plate distributor at presence of silica particles: and For ring distributor at presence and absence of silica particles: .With R ² value equal to 0.997 and 0.991 for the two relations respectively. From the results, we obtained that for perforated plate distributor the gas holdup related with superficial velocity linearly at L/D=6,7.5 () and the relation tends to be polynomial ( )at L/D=10 . while for ring distributor the relation was almost gave a power equation() each parameter of this (a,b,c) are varied with operation condition .