A Calciner at its Best

Abstract

Results from one of the world’s largest cement plants are presented in this paper. The plant incorporates many innovative technologies including being the largest single kiln and a preheater tower with dual-sting ‘hybrid’ low-NOx and CO inline calciner. Commissioned with coal firing, the plant later switched to firing a blend of coal and petcoke in the kiln. The calciner has a seven-second residence time and is capable to burn several types of alternative fuels including bigger and denser fuels such as tire chips and/or solid recovered fuels.Prior to calciner installation, a detailed mathematical modeling exercise using mineral interactive computational fluid dynamics (MI-CFD) was carried out. The simulated results showed higher level of coal burnout in seven seconds’ gas residence time with about 95% meal calcination levels. The CO and NOx emissions were found to be extremely low. The predicted values were later found to be reasonably close to plant data.Plant analysis for the last ten years of operation are presented. The lower NOx emissions enabled the plant to use no or very little SNCR allowing for savings of between 1-2 $M per year, as compared with other plants. Some data and simulated results are presented to highlight calciner performance and, where possible, results are compared with other state of the art calciners. The achieved success from the plant can be replicated to other plants through creating similar combustion and process conditions.