Combustion behaviour of pulverized oil shale in a circulating fluidized bed

The aim of this work is to modify an exiting circulating fluidized bed combustion unit in order to directly burn pulverized oil shale. The modification involved the design of a feeder so as to continuously supply the fuel to the unit at a uniform rate so that the combustion process proceeded smoothly. Further, a heat exchanger was designed and installed inside the unit to extract heat that may be used for controlling the bed temperature and for domestic heating purposes. During experimental work, chromel-alumel thermocouples were used to measure the temperature distribution along the height of the bed. Further, the gas chromatography technique was used to analyse the exhaust gases from the bed. Finally, the remaining ash in the bed was analysed for the unburnt carbon and the combustion efficiency of the combustor was determined. Using the newly designed modifications in the combustor, it was found that oil shale can be burnt smoothly and continuously. The maximum average bed temperature obtained was 940°C, while the combustion efficiency ranged between 91% and 96%.