Investigation of Superficial Gas Velocity and Solid Concentration Influence on Heat Transfer Coefficient in Slurry Bubble Columns

Heat transfer is a very important phenomenon for modeling heat equipment and scale up of slurry bubble reactors. For studying local heat transfer coefficient in slurry reactors, a column of 30 cm diameter and of about 3 m height which meets industrial reactor region was designed and constructed. In the experiments, 50-μm SiO2 powder having the same size of the catalyst of Fischer-Tropsch process was used as the solid phase and paraffin and air were used as the liquid and gas phases respectively. A specially designed heat transfer probe was used for measuring local heat transfer which consists of an electrical heat source element and two thermocouples for probing surface and fluid temperature measuring. By using this probe, local heat transfer coefficient was measured and the influence of superficial gas velocity and solid concentration were investigated. In all experiments, slurry phase height to the column diameter ratio was 4. The results showed that increasing the gas velocity from 2 to 25 cm/s leads to an increase in heat transfer coefficient by about 65%; also an increase in the solid concentration increases heat transfer rate.