Selective Non-Catalytic Reduction of Nitric Oxide Using Urea Solution in Industrial Combustion Chambers

Abstract

Nitric oxide emissions generated from industrial combustion systems contribute significantly to atmospheric pollution, acid rain formation, and photochemical smog, necessitating the development of efficient nitrogen oxide control technologies. This study investigates the selective non-catalytic reduction (SNCR) of nitric oxide using urea solution in industrial combustion chambers under varying operating conditions. The research focuses on evaluating nitrogen oxide reduction efficiency, reaction kinetics, and operational parameters influencing the performance of the SNCR process. Experimental analyses were conducted to examine the effects of combustion temperature, urea injection rate, residence time, flue gas composition, droplet size, and oxygen concentration on nitric oxide conversion and by-product formation. Results demonstrated that urea-based SNCR effectively reduced nitric oxide emissions through thermal decomposition and reaction with nitrogen oxide species to form nitrogen and water vapor. Optimized temperature conditions significantly enhanced reduction efficiency while minimizing ammonia slip and secondary pollutant generation. Kinetic evaluation revealed that reaction performance is strongly dependent on the temperature window, mixing behavior, and reactant distribution within the combustion chamber. The study further indicated that appropriate injection strategies and residence time control improve reagent utilization and overall process effectiveness. Comparative assessment with catalytic reduction technologies confirmed that SNCR offers advantages such as lower capital cost, simpler system design, and easier integration into existing combustion facilities. Furthermore, the process demonstrated stable operation under industrial combustion conditions with improved environmental compliance performance. The findings highlight the potential of urea-based selective non-catalytic reduction as an efficient and economically viable approach for controlling nitric oxide emissions in industrial combustion and thermal processing systems.