Predicting the onset of transient gas pressures and flow rate instabilities for contact bed flow of a granular solid in a sloping standpipe

The work presented in this dissertation studies the flow of a granular solid in a contact-bed standpipe. It examines the flow rate and gas pressure gradients which produce voids. These voids can grow, filling the entire standpipe and causing loss of pressure seal. The theoretical work used a soil mechanics approach to describe the flow through sloping standpipes. Equations describing the affect of cohesion on standpipe flow and a model predicting the onset of void formation are presented. This work also develops the relationship between the standpipe slope angle and the ratio of the solid-contact pressure against the standpipe wall to the solid-contact pressure directed along the standpipe.