Numerical simulation of oxygen-enriched combustion in a rotary kiln in the primary air and the secondary air respectively

Aiming at a real-size rotary kiln, numerical simulations were carried out for air combustion, primary air oxygen enrichment, and secondary air oxygen enrichment conditions, respectively, in order to explore the influence of oxygen-enrichment methods on heat transfer and NOxgeneration in the rotary kiln. The results show that by using oxygen-enriched combustion technology, the shape of the high temperature zone generated by the combustion is almost unchanged, in the shape of a willow leaf, and as the combustion rate of volatiles and char increases, the overall temperature of the flame increases, and thus the amount of radiation received by the wall surface of the rotary kiln also increases. Comparing the two oxygen enrichment methods, it can be found that the oxygen enrichment in the primary air results in the most obvious increase in average temperature, and the total radiation received by the wall surface in the burning zone is increased by about 6.76%, but the NOxgeneration is also increased significantly, with the NOxat the outlet increasing from 1099 ppm to 1303 ppm. © 2022 Bauverlag BV GmbH. All rights reserved.