The oxidation of calcium sulphide at the temperatures of fluidised-bed combustors

摘要: Calcium sulphide is a major product from coal gasification processes that use limestone as desulphurisingagent; also, it may be formed in fuel-rich regions of fluidised-bed combustors. Complete conversion CaS to CaSO 4 via the gas-solid reaction CaS+2O 2 →CaSO desirable allow safe disposal bed ash material. This has been investigated at temperatures 650°C 1050°C using thermogravimetric analysis. The results revealed, inter alia, discontinuity formation with increasing temperature: Above 850°C, CaO also evolution SO . shown result apparent solid-solid CaS+3CaSO →4CaO+4SO , which occurs above about 900°C, when liquid melt probably produced. observation production 850°C during oxidation, however, consequence exothermicity forming raising particle temperature thereby initiating between and reactant CaS. rise temperature, coupled change porosity caused by both formation, gives slightly sigmoidal mass-time plots experiments. A kinetic study oxidation first order O rate constant 4.5±2.0×0 −4 exp[−(5.7±1.5) 10 3 / T ] m/s. overall conclusion that, although converted operating combustors, these two solids starts for melt, undesirable