Gas and solid flow patterns in the loop-seal of a circulating fluidized bed

Gas and solid flow patterns in a loop-seal operated as solid re-injection device between the downcomer and the riser of a lab-scale cold CFB apparatus were characterized under a broad range of operating conditions by a combination of methods, including measurement of pressure time series along the CFB loop, solid mass flux along the riser and solids and gas tracing into the loop-seal. Analysis of results from solids and gas tracing tests highlights the role of both solid downflow in the supply chamber and gas cross-flow between the loop-seal chambers on the fluidization patterns. An approximate criterion is given for the onset of gas “leakage” between the two loop-seal sections, relevant to loop-seal applications in dual interconnected fluidized beds (DIFB).