Potential in utilising furnace off-gas at a ferrochrome smelter with gas engines

In South Africa the current electrical energy crises and the possibility of carbon tax forces ferrochrome smelters to improve the efficiency of the plant and also reduce the carbon emissions at the same time. This can be done by utilising the waste energy available at the plant. This paper presents a technical evaluation of the utilisation of furnace off-gas, rich in carbon monoxide, by using gas engine-generator sets to convert chemical energy into electrical energy - referred to as cogeneration in this paper. Off-gas characteristics and electrical energy generated by such an existing cogeneration plant, at an ilmenite smelter plant, are shown. The ilmenite smelter is used as reference, because of the similarity in gas composition and volume to the off-gas produced by ferrochrome furnaces. Plant efficiency and the reduction in electrical energy bought from Eskom is determined. The results from the existing cogeneration plant is used to determine the possible electrical energy that could be generated by a similar gas engine plant, at a ferrochrome smelter. In this paper the potential of such a cogeneration plant will be evaluated for implementation at a ferrochrome smelter.