Fouling and gasification studies

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Deposition onto surfaces of heat exchangers and other processing equipment is costly in terms of energy and operating efficiency. If root causes of fouling can be established, design or operating changes can be made to mitigate the problem. Mechanisms leading to deposition in hydrocarbon systems include autoxidation, polymerization, incompatibility of asphaltenes, coking reactions, iron sulphide formation etc. The objectives of this research are to determine the underlying mechanisms of fouling for certain classes of complex fluids ( eg sour crude oils), and obtain a quantitative expression for the fouling rate which operators or designers can use to control fouling. The research approach is to use batch reactors for reaction and precipitation studies, followed by fouling measurements in re-circulation heat transfer loops. Effects of process variables and extensive characterization of fluids, precipitates and deposits helps to identify mechanisms. Models are used to express results and make predictions of rate behaviour. Tools include asphaltene flocculation titrations, solvent fractionation of fluids and deposits, and standard methods such as SEM, EDX, TGA and DRIFTS. Topics include crude oil fouling; relation between asphaltene precipitation, coking and fouling in heavy oil systems; deposition of fine droplets from heavy oil vapour systems; and autoxidation fouling in naphthas and gas oils. Novelty lies in the comprehensive research approach, the real fluids studied, and the unique facilities available for the research which permit realistic data under industrially important conditions. Research is also underway supporting the concept of a future biomass refinery. Similar approaches to those given above are being applied to study biomass pyrolysis oil behaviour during heating. Our previous gasification research with coal and biomass is being extended to produce synthesis gas from bio-oil/wood char slurries.