Abstract—Many cement companies are burning waste-derived fuels in cement kilns due to different advantages. Meat and bone meal (MBM) is such a fuel which gives no net CO2 emissions to the atmosphere. However, some characteristics of waste-derived fuels can impact the kiln process adversely. In the present study, computational fluid dynamics (CFD) modelling is used to analyze the combustion characteristics when the primary coal energy is partly replaced by MBM. The investigated replacement ratios (by energy) are 10%, 32%, 59% and 90%. Unburnt fuel char can disturb the internal cycles of sulphur, chlorine and alkalis in the cement kiln system and thereby negatively impact the process operation as well as the product quality. A linear correlation between equilibrium gas temperature and fuel replacement ratio was found, but the correlation between overall char burnout and fuel replacement ratio was found to be positively deviated from a linear correlation. The positive deviation increases up to a fuel replacement ratio of 58%. Above this value, the positive deviation starts to drop. Therefore, from a char burnout point of view, a fuel replacement ratio of 58% can be seen as a guiding value for optimum replacement of coal by MBM.
Index Terms—Cement rotary kiln, CFD, fuel char burnout, multi-fuel combustion.
W. K. Hiromi Ariyaratne and Lars-André Tokheim 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, Lars.A.Tokheim@hit.no).
Morten C. Melaaen is with Telemark University College, Faculty of Technology, Kjølnes Ring 56, Post box 203, N-3901 Porsgrunn, Norway (e-mail: morten.c.melaaen@hit.no).
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Cite: W. K. Hiromi Ariyaratne, Morten C. Melaaen, and Lars-André Tokheim, "CFD Modeling of Multi-fuel Combustion of Coal and Meat and Bone Meal (MBM) in a Cement Rotary Kiln," International Journal of Modeling and Optimization vol. 5, no. 6, pp. 15-21, 2015.
