Heat-transfer performance and pressure drop in a gas-solid circulating fluidized bed spiral-plate heat exchanger

摘要

A gas-solid circulating fluidized bed spiral-plate heat-exchange apparatus is designed and built. The heattransfer performance and pressure drop of gas-solid two-phase flow are then investigated by varying the amount of added particles (0.5-2%), air flow rate (80-125 m(3)/h), and particle types. Air is heated by circulating hot water with constant inlet temperature in the spiral-plate heat exchanger. Glass bead (GB) and polyformaldehyde particles are selected as the inert solid particles. Results show that particle addition improves the heat-transfer performance of the spiral-plate heat exchanger. The maximum heat-transfer enhancing factor is 29.8% when GB2 particles are added at epsilon = 1% and V-g = 80 m(3)/h, and the corresponding pressure-drop ratio is 30.74%. In general, the enhancing factor initially increases and then decreases with increased amount of added particles. However, the variation trend of the enhancing factor with air flow rate depends on the amount of added particles and particle types. The pressure-drop ratio increases with increased amount of added particles. Three-dimensional diagrams are established to display the variation ranges of the enhancing factor and pressure-drop ratio under different operating parameters.