1992 Volume 18 Issue 6 Pages 849-855
Velocity and stress profiles related to particles in moving beds are estimated theoretically. based on a flow model that describes the stress-strain relationship of flowing bulk solids. This model takes account of the expansion in bulk volume of the particle bed during shearing deformation. The validity of the theory is examined by applying the model to a gas-solid crossflow moving bed and gravity flow of solids (without gas flow) through a vertical tube. Further, the theory is extended to predict the behaviour of solids with gas flow in a vertical tube. Predicted velocity and stress profiles depend on the mode of gas-solid contact, cocurrent or countercurrent. The frictional force of solids on a wall surface increases markedly in cocurrent flow, which induces considerable lag of particle velocity on the wall surface. The model parameter indicating the bulk volume expansion effect is a function of the particle velocity, and is almost unaffected by the flow rate of gas moving through the particle bed.
