Numerical modeling of the calcination process in a cement kiln system

Abstract

The calcium carbonate decomposition into calcium oxide and carbon dioxide is a key process step in a cement kiln. The reaction requires thermal energy input, and pulverized coal is the fuel typically used for this purpose in the cement industry. Coal can in many cases be replaced by different types of alternative fuels, but this may impact process conditions, emissions or product quality. In this study, CFD simulations were carried out to investigate the possibility to replace 50 % of the coal by refuse derived fuel (RDF). The spatial distribution of gas and particle temperatures and concentrations were calculated, and the simulations indicated that replacement of coal by RDF resulted in a reduction of fuel burnout, lower gas temperatures and a lower degree of calcination.