This work concerns the study of the influence of air flow on yields of gas emissions during the combustion of a mixture of millet stalks and polyethylene bags in a prototype of kiln. During these investigations, we looked at the rate of residual oxygen (O2) and emissions of carbon dioxide (CO2) and nitrogen monoxide (NO) as a function of primary air flow (Q1) and secondary (Q2). The potters kilns considered are those fueled by natural air flow. The primary air flows ranging from 45 to 85 Nm3.h-1 and secondary air flows from 20 to 60 Nm3.h-1. To conduct this numerical study, the model used is "REACTOR" based on the code CHEMKIN II. The modeled area is split into a multitude of perfectly stirred reactors (PSR) and the kinetic model has 893 species and 113 reversible chemical reactions. The rate of residual oxygen increases linearly with flows of primary and secondary air. The increasing of the secondary air allows in a first time, to improve combustion and causes a decrease in oxygen consumption. For CO2 emissions, an increasing of the primary air flow leads to higher rates of conversion of carbon into dioxide of carbon in the temperature range studied (850 to 950°C). The carbon dioxide is produced very quickly within the primary combustion zone. The supply of secondary air allows a lower of CO2 levels by dilution phenomenon, the latter being formed in primary combustion zone. Concerning NO it appears that for Primary flows less than or equal to 75 Nm3.h-1, NO emissions are partly controlled by the concentration of oxygen in the reactive medium. For primary airflows over 75 Nm3.h-1, the formation of NO is mainly controlled by the temperature of combustion. Finally, whatever the proportion of plastic, the secondary air injection does not influence NO production.

débit d’air primaire débit d’air secondaire simulation numérique