Other Information Lecturer (1966), Senior Lecturer (1991), Head of Division of Engineering Teaching Organisation 1998-2001
Professional Qualifications and Memberships:
Fluidised bed Freeboard Studies
Freeboard studies of fluid bed systems are important because bed material is lost by freeboard elutriation and reactions frequently continue in the dilute freeboard space. The former leads to losses of valuable catalyst materials and malfunctions of downstream equipment, while e.g. in fluid bed polymer production polymer particles carried into this region continue to grow under conditions of very poor temperature control, leading to off-specification product and even melting/agglomeration. Freeboard flow has been studied using the whole field velocimetric technique Particle Image Velocimetry, leading to a better knowledge of velocity distributions and flow structures in this region. Most previously assumed models of flow structure and elutriation mechanics in the bed freeboard have been shown to be oversimplified: in particular, the highly unsteady nature of the flow and regions of reverse flow or recirculation have major implications for bedfill losses and continued reaction in the freeboard space.
Fluid Bed Polymer Recycling Studies
Polymer recycling, as at present carried out, usually consists of melting and re-forming to produce articles of fairly low quality and value. Available technology is inadequate to meet even present EU targets for polymer recycling and, under these circumstances, the chemical recycling of domestic and industrial waste plastics to cracker feedstock is attractive. A BP-led consortium has developed a process whereby mixed waste polymer is pyrolysed in an inert fluid bed and converted to a waxy hydrocarbon. Scale-up requires improvement of the heat transfer surface:volume ratio by using immersed tubes and work done in Edinburgh, under BP and EPSRC funding, has investigated the effect of these tubes on the quality of fluidisation, the tube/bed heat transfer coefficient anticipated, the circulation patterns of the solid material and the form of distributor best adapted to these criteria. Work has been carried out using tracer injection, small heat transfer probes and (in collaboration witht the University of Birmingham) Positron Emission Partilce Tracking. It appears that tubes without extended surfaces and perforated plate or tuyere distributors give superior performance for this application.