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Combustion experiments of Shidongkou sewage sludge from China were carried out by using a small lab-scale fluidized bed, and the effects of moisture content and feed rate of sewage sludge and the transfer of heavy metals were analyzed. Studied sewage sludge with a moisture content of no more than 40% can stably burn in the fluidized bed without any auxiliary fuel input. Enhancing the bed temperature of the dense phase, strengthening the gas–solid mixing of dense phase, and increasing the feed rate of sludge are very necessary for the ignition of sludge with higher moisture content; however, higher feed rate will give rise to an increase of both the incomplete combustion heat loss and the physical absorbing heat amount of new sludge into the fluidized bed, reducing the bed temperature. Gaseous pollutants from the fluidized bed were discussed under different experimental conditions. At last, it was presented that heavy metals except Zn within sewage sludge are mostly concentrated in bottom ashes and bag filter ashes.

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The uncertainty about the current prices of petroleum, its growing worldwide consumption and limited availability have motivated many countries rich in oil shale resource to explore more efficient retorting technologies to widely produce and use shale oil as an alternative. On the basis of the retorting technology progress and the characteristics of oil shale, this paper recommends a combined system with a fluidized bed (FB) reactor for retorting oil shale and a circulating fluidized bed (CFB) boiler for burning semicoke and fuel gases, realizing the effective and clean use of oil shale. The FB retort and CFB boiler are arranged side-by-side, and hot circulating ash and semicoke will be conveyed from one side to the other. Both CFB circulating ash and fuel gases as fluidizing gases of the FB retort are proposed to be heat carriers together, transferring the combustion heat from the CFB to oil shale in the FB retort. Retorting temperature, heat capacity distribution of heat carriers and parameter optimization of the whole system are further discussed as key issues.