Increased Coal Replacement in a Cement Kiln Burner by Feeding a Mixture of Solid Hazardous Waste and Shredded Plastic Waste

Abstract

The present study aims to find the maximum possible replacement of coal by combined feeding of plastic waste and solid hazardous waste mixed with wood chips (SHW) in rotary kiln burners used in cement kiln systems. The coal replacement should be achieved without negative impacts on product quality, emissions or overall operation of the process. A full-scale experiment was carried out in the rotary kiln burner of a cement kiln by varying SHW and plastic waste feeding rates. Experimental results were analysed using fuel characteristics of coal, SHW and plastic waste. The results revealed that feeding 3 t/hr of SHW plus 2.5 t/hr of plastic waste was acceptable, although giving a slightly lower production rate. This waste feeding rate is equivalent to 52% of coal energy replacement in the main burner. The limiting factor is the free lime content of the clinker. A comparable result for the reduction in production rate could be found from a simulation using a mathematical model of the kiln. Results from the present study were also compared with results from two previous studies, in which SHW and meat and bone meal were the solid alternative fuels used.