An Investigation for Generation of Energy Conservation Measures for Sponge Iron Plants Using Process Integration Principles

During the operation, a tremendous amount of heat is generated in the coal based sponge iron plant and a significant part of this heat associated with the waste gas, remains unutilized. While utilizing this heat in the process the energy demand of the process may be reduced, which decreases the coal consumption as coal is the only source of energy in this plant. Further, it is seen that existing plant consumes 5.57 times more energy than theoretical value. This information advocates the basic motivation of the present study. To utilize the heat associated with waste gas pinch analysis is applied on the actual data of plant and identified three feasible cases for energy conservation. For these cases capital investment required for retrofitting as well as total profit in terms of coal and water saving are compared and best design is selected. The best design includes preheating of air as well as feed material to rotary kiln and cooling of kiln outlet using waste gas. It consumes 12.5% less coal in comparison to existing system. The payback period of the best design is 56 days only. This design also satisfies the practical conditions of the process.