Heat-Transfer Characteristics in Slurry Bubble Columns at Elevated Pressures and Temperatures

Abstract

The heat-transfer behavior between an immersed heating surface and the surrounding gas−liquid−solid medium in a slurry bubble column is studied experimentally and analytically. The operating pressures and temperatures vary up to 4.2 MPa and 81 °C, respectively. Nitrogen, Paratherm NF heat-transfer fluid, and 53-μm glass beads are used as the gas, liquid, and solid phases, respectively. The solids concentrations are varied up to 35 vol %, while the superficial gas velocities are varied up to 20 cm/s. The effects of gas velocity, solids concentration, pressure, and temperature on the heat-transfer coefficient are examined. It is found that pressure has a significant effect on heat-transfer characteristics. The heat-transfer coefficient in a slurry bubble column decreases appreciably with an increase in pressure. It is noted that the variation in the heat-transfer coefficient with pressure is attributed to the counteracting effects of the increased liquid viscosity, decreased bubble size, and increased gas h...