Investigation of Environmental Emissions Reduction in a Rotary Cement Kiln

Environmental pollutants, particularly carbon dioxide and carbon monoxide, are mainly caused by strategic industries such as the cement industry. These pollutants are due to fuel combustion and chemical reactions during the production process. Thus, developing process optimization methods that do not significantly impact kiln performance is highly important. This study presents a mathematical description of a real kiln based on the Spang model. A new and cost-effective method, increasing the excess air in the rotary kiln under constant operating conditions, is proposed to reduce pollutants. This method is especially suitable for active cement plants. The rotary kiln is a slightly inclined horizontal cylinder in which raw materials are in contact with the hot air. Modeling and optimization of the kiln were carried out through transport phenomena equations, incorporating operational parameters and reaction kinetics. This model also considers the mechanisms of primary and secondary reactions resulting from incomplete combustion. The results showed that increasing excess air to ۳۰% reduced pollutant concentrations in the exhaust gas. The efficiency of the kiln remained nearly unchanged, while the amount of carbon monoxide decreased significantly.

کلیدواژه ها:

Cement industry ، Rotary kiln ، Environmental Pollutants ، carbon monoxide emission ، Mathematical modeling