Presented at the STAR Global Conference 2012.
Avoiding the formation of rings in rotary kilns is an issue of primary concern to the cement production industry.
We developed a numerical combustion model that revealed in our case study that rings are typically formed in zones of maximal radiative heat transfer. This local overheating causes the overproduction of the liquid phase of the granular material that tends to stick to the oven's wall and to form rings.
To counteract this phenomenon, we propose to increase the amount of secondary air injected to cool the oven. Experimental validation at the plant has repeatedly shown that this solution is indeed effective. For the first time in years, the kiln has been operating without unscheduled shut-downs, resulting in a monthly five-digits cost saving. The above mentioned model was developed with STAR-CCM+.