Heat transfer between dispersed liquid metals and gases in packed beds

Abstract

The rates of heat transfer occurring during the counter-current contacting of dispersed liquid metals and gases in towers packed with ring and spherical packings are examined. Using mercury and air as the heat exchange fluids, heat transfer studies at room temperature are described and the heat transfer mechanisms examined. Heat transfer data are also presented for the contacting of molten lead with preheated nitrogen in a pilot plant scale apparatus. Utilizing the mercury irrigated tower as a room temperature analogue of the high temperature apparatus, the mechanisms operating at high temperature (400° to 600°C) are examined. Two basic heat transfer mechanisms operate below about 400°C: the direct mechanism, which refers to convective heat transfer across the gas/liquid metal interface, and the indirect mechanism, a complex process involving conduction and convection in a sequence such as liquid metal-solid packing-gas phase. Above about 400°C, another mechanism, radiation heat transfer between the liquid metal and its environment, is thought to become significant, but experimental errors masked its detection in the present study.