A coupled kinetic reactor model and reaction pathway analysis for prediction of NOx formation and reduction in cement in–line calciners
Year: 2026
Type: article
Abstract: The continuous tightening of environmental regulations on NO x emissions in the cement industry has led to the implementation of various primary measures for NO x reduction in in–line calciner (ILC) systems. In the present study, a reactor model is developed to improve understanding of NO formation and reduction in coal– and petcoke–fired ILCs. The model consists of a detailed gas–phase chemistry solver implemented in CHEMKIN and a simplified solid–phase chemistry model incorporated into an in-house solver. The two solvers are coupled, and calculations are performed iteratively. Model predictions are compared with industrial measurements from four different ILC operating conditions and show acceptable agreement. Important mechanisms as well as operation/physical parameters affecting NO formation/reduction in the studied ILCs are identified. The dominant mechanisms for NO formation and reduction are predicted to be NO formation from char–nitrogen, while NO is reduced both by char (or catalyzed over char) and by gas–phase reactions. The contribution of gas–phase reactions varies between cases and depends on the fuel type and operating conditions. A sensitivity analysis is conducted to evaluate the influence of mixing parameters, reburning stoichiometry, and operating temperatures on predicted NO formation and reduction in the studied ILCs. Among the parameters investigated, mixing of tertiary air with the main gas stream and mixing of kiln gas with volatiles released from the solid fuel in the reduction zone are found to have the most significant impact.
Institution: Technical University of Denmark
Language: English
Subfield: Environmental Engineering
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $1,910
OpenAlex ID: W7225640927