Design Modifications for Energy Conservation of Sponge Iron Plants

During the operation in the coal based sponge iron plant, a tremendous amount of heat is generated and significant part of this heat, associated with the waste gas, remains unutilized. It appears worth interesting to modify the process that facilitates the integration of heat available with the waste gas. In the present paper, for the utilization of heat of waste gas, two modifications, namely, case-1 and case-2, are proposed based on preheating of inlet streams. In case-1, preheating of feed material is considered, whereas in case-2, preheating of feed material as well as air is accounted. These cases are then compared with the existing waste heat recovery system of the plant based on coal consumption, operating and capital costs, profit, and payback period. It is found that both cases are better than the existing heat recovery system of the plant. However, case-2 is selected as the best heat recovery option. In comparison to the existing system, case-2 reduces coal and water consumption by 30.5% and 72.6%, respectively. Further, case-2 releases minimum waste gas to the atmosphere that makes the process environment friendly.