Techno-Economical Assessment of Alternative Fuels in Cement Kiln

Abstract

Cement kilns are well suited for waste-combustion because of their high process temperature and clinker product and limestone feedstock act as gas cleaning agents. This report will discuss how the addition of easily available waste as fuel, can put cement industry and environment in a better position by the. The studies were done for the 1 million tonne capacity kiln installed in a cement plant located in the state of Tamil Nadu. Three potential wastes namely tyres derived fuel, oil sludge and paint sludge, are taken into account for their use as alternative fuel in the plant. The selected wastes were characterised, on the basis of which the quantity of the alternative fuel that could be added to the rotary kiln can be evaluated. The evaluation is done on the basis of four parameters including heating value of the fuel, cost of the fuel, availability of the fuel and emissions (gaseous as well as heavy metal). CPCB norms restrict the emissions within the limit. It was concluded that maximum 30% of replacement of coal is possible without affecting the quality of cement. Up to this level the emissions were found to be in limit. The use of alternative fuel reduces the use of fossil fuel requirement. Furthermore, this will reduce the burden of waste disposal considerably. This reduced the costs of manufacturing cement by around 8% thus, providing a competitive edge for a cement plant.