Optimum feeding rate of solid hazardous waste in a cement kiln burner

Abstract

Solid hazardous waste mixed with wood chips (SHW) is a partly CO2 neutral fuel, and hence is a good candidate for substituting fossil fuels like pulverized coal in rotary kiln burners used in cement kiln systems. SHW is used in several cement plants, but the optimum substitution rate has apparently not yet been fully investigated. The present study aims to find the maximum possible replacement of coal by SHW, without negatively affecting the product quality, emissions and overall operation of the process. A full-scale experiment was carried out in the rotary kiln burner of a cement plant by varying the SHW substitution rate from 0 to 3 t/hr. Clinker quality, emissions and other relevant operational data from the experiment were analysed using fuel characteristics of coal and SHW. The results revealed that SHW could safely replace around 20% of the primary coal energy without giving negative effects. The limiting factor is the free lime content of the clinker. Results from the present study were also compared with results from a previous test using meat and bone meal.