CFD predictions for cement kilns including flame modelling, heat transfer and clinker chemistry

Clinker formation in coal-fired rotary cement kilns under realistic operati on conditions has been modelled with a commercial axisymmetric CFD code for the gaseous phase including a Monte Carlo method for radiation, a finite-v olume code for the energy equation in the kiln walls, and a novel code for the species and energy conservation equations, including chemical reactions , for the clinker. An iterative procedure between the predictions for the t emperature held of the gaseous phase, the radiative heat flux to the walls, and the kiln and clinker temperature is used to predict the distribution o f the inner wall temperature explicitly, including the calculation of heat flow to the clinker. It was found that the dominant mode of heat transfer b etween the gas and the kiln walls is by radiation and that the heat lost th rough the refractories to the environment is about 10% of the heat input an d a further 40% is used for charge heating and clinker formation. The predi ctions are consistent with trends based on experience and limited measureme nts in a full-scale cement kiln. (C) 1999 Elsevier Science Inc. All rights reserved.