Cement Energy and Environment

.. .. . Constraints in the Use of Refused Derived Fuel (RDF) in Indian Cement Industry Akashneel Banerjee, Rabindra Singh andAshutosh Saxena National Council for Cement and Building Materials Introduction Effective management and disposal of Municipal Solid Waste has already reached a stage of major SHARE Maharashtra, Others, 16% 17% concern in India. According to industry experts about 80 % of the total MSW generated in the country is indiscriminately disposed at dump yards leading to problems of health and Ra~J~~Ca4% Pradesh,3% Gujarat, 5% [],[] Karnataka, 6% environmental degradation. Municipal solid waste (MSW) generation in India Uttar Pradesh, 10% Andhra 9% Pradesh, goA, is about 75 million tonnes per annum. Share of MSW Figure 1: Share of MSW generation from major Indian states generation from major Indian states is given in figure 1. Rapid urbanisation, uncontrolled population growth and rising per capita income is only going to add to this problem. In India, the responsibility for handling wastes is with local municipalities, but they face severe challenges in undertaking these operations due to lack of funds, skilled manpower and choice of method/technology for waste disposal. Co-processing of MSW in cement kilns is one of the best solutions for addressing the problem of MSW management in India. About 7 million tpa RDF is available for MSW, out of which only -1.4 million tpa is used for co-processing. This indicates the requirement of building awareness for RDF availability; state of the art facility for pre-processing, to make RDF available at consistent quality and quantity. Use of Refused Derived Fuel (RDF) as a replacement of traditional fossil fuels has been a potential area for reducing carbon foot print of Cement industry. RDF available for Indian cement industry is the product of pre-processing of Municipal Solid Wastes (MSW). Technology constraints for RDF co-processing • In India majority of the cement kilns are operating at or above their rated capacities. Hence, increase of exit gas volume can create a capacity bottleneck for major process fans and dedusting systems. • Low calorific value and high ash & moisture content of RDF reduces flame temperature and increases stoichiometric 0 2 requirement, which increases the exit gas volume and if the preheater ID fan has capacity limitation then production capacity automatically gets reduced. • Inconsistency in input quality and presence of high volatile chlorides and sulphur, increases chances of coating formation in kiln inlet & lower preheater stages. Th is imparts poor heat exchange between exit gas and kiln feed, leading to increased heat consumption , indicated by higher preheater exit temperature. • Due to inconsistent quality and fluctuating feed rate the burning zone of kiln becomes less stable with inconsistent liquid properties, like surface tension, viscosity etc. • Unstable coating formation with frequent thermal shocks due to continuous adjustment 17