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The regeneration of sulphated limestoneTucker, Richard Frank January 1987 (has links)
Fluidised bed combustion offers potential advantages over conventional power generation systems, particularly with respect to sulphur capture using injected limestone. The stone calcines on entry to the hot bed, forming CaO, and then reacts with SO<SUB>2</SUB> to produce CaSO<SUB>4</SUB>. Regenerative schemes aim to reduce the sorbent loading by stripping off the sulphur from the spent limestone which is then reused. This subject of this dissertation is an investigation into the fundamentals of the regeneration of sulphated limestone by reductive decomposition. Following a detailed discussion of the thermodynamic limitations on the reaction system, attention is focussed on the kinetics of the reductive decomposition scheme. The results of a study on the reaction of CaSO<SUB>4</SUB> powder with CO are reported. This made use of two experimental techniques, X-ray powder diffraction and thermogravimetric analysis. These experiments highlighted the major features of the reaction scheme and allowed the study of two special cases, the sulphidation of CaSO<SUB>4</SUB> to produce CaS only and the solid-solid reaction between CaS and CaSO<SUB>4</SUB>. The major experimental technique used for this work was the batch addition of limestone to a fluidised bed. After a brief discussion of the results of sulphation experiments, typical regeneration experiments are described. By varying the test conditions as well as performing several special experiments, a mechanism for the overall reaction is deduced. The effect of the operating variables on the product split is then explicable. The evidence suggests that the closed pores resulting from the sulphation reaction lead to strong diffusion resistance on regeneration which controls the rate during the early and middle stages. By utilising high CO<SUB>2</SUB> concentrations the formation of CaS was inhibited; the reaction was then amenable to quantitative analysis which revealed an approximate first order dependence on CO concentration and an activation energy of 110kJ/mol. One method for reducing the quantities of CaS produced is to operate the fluidised bed in a two-zone fashion i.e. with oxidising and reducing regions. An investigation into this reactor configuration is included with particular attention paid to the oxidation of CaS. The results obtained are explicable in terms of the results from the single zone bed and allow the effects of operating variables on the reactor performance to be predicted. Finally, the mathematical modelling of the gas-solid reactions is considered. The changing grain size model is introduced by considering the sulphation of limestone. The final conditions from this model then form the initial conditions for the regeneration model, which considers mildly reducing conditions only. The final model then uses as a basis the mechanism proposed in chapter 5 and is applied to the thermogravimetric analysis results.
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The control of fluidised combustorsGray, D. T. January 1986 (has links)
No description available.
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Gasification and combustion in fluidised bedRathbone, R. R. January 1986 (has links)
No description available.
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Circulating fluidised bedsBolton, L. W. January 1987 (has links)
No description available.
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Vibration and fluidisation of powdersEdwards, D. N. January 1985 (has links)
No description available.
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Electrolytic treatment of effluent streams using novel technologiesAndrews, Lisa Clare January 1998 (has links)
No description available.
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In-bed oxygen levels in a fluidised bed combustorMalik, Shahid Raza January 1990 (has links)
No description available.
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Gas-solid fluidisation : an improved method for the preparation of chemically bonded stationary phasesAkapo, S. Olufolabi January 1989 (has links)
No description available.
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Limestone as a desulphurising sorbent in power generating systemsDavies, Neil Harvey January 1994 (has links)
No description available.
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Development of a coalesced arc plasma reactor for minerals processingPatterson, M. C. L. January 1986 (has links)
No description available.
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