The environmental and energy impact of alternative fuel usage for cement production

摘要

Waste to energy through conventional mass burn facilities has been in operation for nearly 30 years. The attention to environmental concerns and security of energy sources has increased the focus of using waste streams as a resource, particularly recovery of energy. Cement production is the largest worldwide materials based high temperature process typically requiring about 3600 kJ per kg of clinker therefore needs a large supply of fuels. The primary specification for fuels is a sufficiently large heating value to achieve required temperatures. However the chemical composition of the fuel must also be considered to produce high quality cement. Since 2003 the price of fuel has increased from $30 per tonne to about $70, therefore alternative sources have been developed such as biomass and refuse derived fuel (RDF). This has led to an increase of alternative fuel consumption from approximately 16% in 2000 to nearly 30% currently resulting in the utilization of more than 16 tonnes of wastes. This paper will present the analysis of RDF utilization for co-firing applications in cement kilns operated by CEMEX. Analysis of fuel composition and emission data that have varying amounts of co-firing of conventional fuels and RDF will be presented. Specifically, overall material and energy balances and environmental assessment to determine potential impact on waste diversion from landfills. Finally, a comparative analysis of the combustion performance between a kiln and other combustion technologies including coal fired power generation plants and waste to energy plants will be shown.