Numerical study of Selective Non-Catalytic Reduction (SNCR) technique for NOx Emission Reduction in Heavy-Duty Engines

Stringent nitrogen oxide (NOx) regulations are crucial for minimizing environmental harm and enhancing public health. The Selective Non-Catalytic Reduction (SNCR) technique is an effective after-treatment method for reducing NOx emissions in combustion systems. By injecting a reagent, typically ammonia or urea, into the flue gas within a specified temperature window, SNCR facilitates the chemical reaction that converts NOx into harmless nitrogen and water. The optimal temperature range for this reaction is critical for maximizing efficiency and effectiveness. The primary advantage of the SNCR technique is its lower installation and operating costs in comparison to other after-treatment methods. The partners involved in this proposal are highly interested in implementing the SNCR method to reduce NOx emissions from heavy-duty engines. This proposal aims to develop a numerical model to evaluate the NOx reduction potential in heavy-duty engine applications using the SNCR method. The model will enable the analysis of key parameters, including the injection site temperature and the reagent-to-NOx concentration ratio, to determine their impact on NOx reduction.

Eindrapportage

In this project, the potential of Selective Non-Catalytic Reduction (SNCR) to reduce nitrogen oxide (NOx) emissions in heavy-duty diesel engines was investigated. These engines are widely used in transport and industry and contribute significantly to air pollution.
SNCR is a relatively simple and cost-effective method in which a reagent, such as ammonia or urea, is injected into hot exhaust gases. Within a specific temperature range, these substances react with NOx to form harmless nitrogen and water.
Within the project, a numerical model was developed to simulate the behavior of these reactions under various conditions. Key parameters such as exhaust gas temperature and the reagent-to-NOx ratio were analyzed.
The results show that SNCR has potential as a supplementary technique for NOx reduction. However, the typical temperature range of the exhaust gas in heavy-duty engines does not match with the required temperature range for efficient NOx reduction. In addition, the study showed that the SNCR process requires time to reach chemical equilibrium. This makes integration with existing after-treatment systems, such as Selective Catalytic Reduction (SCR), challenging, particularly under dynamic engine operating conditions.
The project contributed to knowledge development in education and strengthened collaboration between research institutions and industry.