Abstract—Increased use of alternative fuels in cement kilns is a trend in the world. However, replacing fossil fuels like coal with different alternative fuels will give various impacts on the overall kiln process due to the inherent fuel characteristics. Hence, it is important to know to what extent the fossil fuels can be replaced by different alternative fuels without severely changing process conditions, product quality or emissions. In the present study, a mathematical model based on a mass and energy balance for the combustion of different alternative fuels in a cement rotary kiln was developed. First, the impact of different fuel characteristics on kiln gas temperature, kiln gas flow rate and air requirement were observed by using coal (reference case), meat and bone meal (MBM), two different wood types, refuse derived fuel (RDF) and a mixture of saw dust and solid hazardous waste as the primary fuel. It was found that the key process parameters depend largely on the chemical characteristics of the fuel. It appears that MBM shows quite different results from other alternative fuels investigated. Next, simulation of combustion of a mixture of coal and MBM in the rotary kiln burner was carried out in three steps in order to find the reduction in production capacity compared to the reference case. Around 9% of reduction in clinker production rate could be observed when replacing 59% of the coal energy input. Results from a full-scale test using the same mixture of coal and MBM verified the simulation results.
Index Terms—Air requirement, alternative fuels, production capacity, rotary cement kiln burner.
The authors are with Telemark University College, Department of Process, Energy & Environmental Technology, Faculty of Technology, Kjølnes Ring 56, Post box 203, N-3901 Porsgrunn, Norway (e-mail: hiromi.ariyaratne@hit.no, edirisinghe.m@gmail.com, morten.c.melaaen@hit.no, Lars.A.Tokheim@hit.no).
[PDF]
Cite: W. K. Hiromi Ariyaratne, E. V. P. J. Manjula, Morten C. Melaaen, and Lars-André Tokheim, "Mathematical Model for Alternative Fuel Combustion in a Rotary Cement Kiln Burner," International Journal of Modeling and Optimization vol. 4, no. 1, pp. 56-61, 2014.