Heat transfer and solids mixing in slugging gas fluidised beds

Three different models for the mixing of solids in a slugging gas fluidised bed are proposed; one model is an extension of the already established bubbling bed model, the other two models represent the dispersion of solids in the bed by perfectly mixed regions, the analysis is rather similar to that developed for perfectly mixed tanks in series. The models are tested with experimental results of the axial solids mixing in 5.1, 10.2 and 21.8 cm. diameter slugging beds. The solids mixing was measured by studying the axial trnsport of heat through the slugging fluidised bed. Values of the slug properties in the bed (slug rise velocity, slug length, interslug spacing and slug frequency) are also required to test the models and these properties were measured in the slugging bed simultaneously with the axial solids muixing. A number of different solids have been used to form the slugging bed, since the models predict that the volume specific heat of the solids is an important parameter affecting the axial thermal conductivity of the bed. [...]