Tackling Air Pollution: Why Reducing NOx Emissions in Industrial Diesel Engines Matters

The latest data from the University of Reading:

• NO₂ (Nitrogen Dioxide):  Industrial diesel engines remain a significant contributor to the total emissions of nitrogen oxides.
• PM2.5 (Fine Particulate Matter):  PM2.5 levels have also declined. But their reduction is more complex, with long-range pollution transport from continental Europe exerting a significant influence.
• O₃ (Ground-Level Ozone):  This is where the challenge intensifies. Since 2015, ozone pollution has soared by 17%, and currently exceeds the World Health Organization’s target twice as frequently as before. This is problematic because ozone is not directly emitted. On the contrary, it is formed when sunlight triggers the chemical reaction between nitrogen oxides and volatile organic compounds (VOCs).  

7 Proven Strategies for Reducing NOx Emissions with DEF

Strategy 1: Precise Metering to Prevent Ammonia Slip

Ammonia slip—excess ammonia escaping the SCR system leads to corrosive ammonium bisulfate buildup, equipment clogging, and elevated maintenance. Conversely, insufficient injection results in non-compliance. Therefore, precise metering is imperative.

• Coriolis Flow Meters’ Advantage:  These meters offer ±0.1% accuracy.  
• Preventing Ammonia Slip:  Real-time monitoring and adjustments diminish excess ammonia, safeguarding equipment and catalysts.
• Guantong’s Solution:  Guantong’s metering systems integrate advanced process control instruments. These furnish real-time data for optimal NOx control.
• Case Study:  A power plant employing Guantong’s Coriolis flow meters in its DEF system curtailed ammonia slip to less than two ppm, extending catalyst life by 30%.

Strategy 2: Choosing ISO 22241-Compliant DEF

The quality of diesel engine exhaust fluid (DEF) critically impacts SCR system performance.5 Substandard DEF can “poison” the catalyst. This makes proper DEF quality essential.

For DEF quality, the ISO 22241 international standard stipulates that a qualified DEF must contain 32.5% high-purity urea and 67.5% deionized water.

Strategy 3: Addressing Urea Crystallization with Urea Pyrolysis

Urea crystallization is a super huge challenge in the DEF system. This problem usually occurs when the urea solution cannot decompose below 190°C, eventually forming solid deposits that clog syringes and pipes, causing serious consequences.

What causes crystallization? The main reason is that the temperature is too low, which leads to incomplete decomposition of urea. This subsequently forms the main precursor of triuric acid crystals.

To solve this problem, Guantong has provided an innovative urea cracking furnace. It operates at high temperatures (350-600°C), whichensures that the urea solution is completely converted into ammonia and eliminating the risk of crystallization. This technology brings many benefits: it reduces maintenance frequency, extends the service life of DEF fuel tanks and injectors, and ensures the continuous and stable operation of the system.

Here is a successful case: A power plant adopted Guantong’s urea pyrolysis technology. Not only has the crystallization problem been solved, but the annual maintenance cost has also been reduced by 20%. Facts have proven that this is a win-win solution.

Strategy 4: Refining Mixing Efficacy through CFD Simulation

The key to the efficient operation of the SCR system lies in the uniform mixing and dispersion of DEF spray and flue gas.

For your choice, here is an important tip: Always choose certified AdBlue DEF, such as our Guantong DEF liquid. This can ensure that your catalyst achieves long-term excellent performance and also complies with all regulatory requirements. Here is a real case: A cement plant once faced a catalyst replacement cost of $10,000 due to inferior DEF, but when they switched to DEF, the system efficiency immediately increased to 95%.

How do we deal with this predicament? We use Computational Fluid Dynamics (CFD) simulation. Guantong has comprehensively adopted this technology to fine-tune the layout of fuel injectors and the design of mixers. By simulating the flow dynamics of flue gas treatment through CFD, we ensure that the DEF liquid fully interacts with nitrogen oxides to achieve peak efficiency.

This technology can also achieve precise “design optimization”. We can carefully calibrate the spray Angle and the geometry of the mixer to reduce ammonia waste while maximizing reaction efficiency.

The benefits are obvious: our solution can increase the reaction efficiency by 10-15%. This means a significant reduction in DEF consumption and a decrease in operating costs.

Strategy 5: Upholding System Integrity for Enduring Performance

For stable and efficient long-term DEF system operation, unwavering system maintenance is imperative. Foregoing maintenance can culminate in DEF storage tank contamination, injector occlusion, and prohibitive downtime.

What steps should be undertaken? We’ve delineated some key maintenance directives:

• Regular cleaning:  Inspect the DEF storage tank monthly and remove any sediment.  
• Pipeline inspection:  Conduct a thorough quarterly inspection of the DEF system pipelines to identify and correct potential leaks and blockages. This can prevent problems before they arise.
• Monitoring equipment:  Utilize integrated process control instruments to supervise the system. Once any real-time abnormal situation is detected, immediate intervention measures can be taken to prevent minor problems from arising.
• Suggestion: Formulate and implement an annual maintenance plan. The support from professional suppliers, such as our Guantong technical team, is highly beneficial.

Strategy 6: Orchestrating Temperature for Peak Reaction

Proficient temperature management is crucial to the efficiency of SCR systems, as the chemical reactions that support the reduction of nitrogen oxides require specific operating temperatures, typically ranging from 190 to 600°C.

• Temperature regulation: Use heaters or insulating materials as needed to prevent the DEF fluid from freezing or overheating in cold conditions; otherwise, degradation will occur
• Monitoring instruments: Deploy precise process control instruments to track temperature fluctuations within the thyristor system, thereby ensuring a stable reaction area.
• Guantong Advantage: The integrated temperature management system creates a continuous and stable environment for the optimal conversion of nitrogen oxides.
• Case Study: A cement plant successfully maintained an SCR efficiency of over 90% under different operating conditions by implementing Guantong’s advanced temperature management solution.

Strategy 7: Empowering Operators for Optimal Performance

The results produced by the most advanced DEF system are as proficient as those of the operators who manage it. Lack of appropriate training may lead to operational errors, reduce the effectiveness of nitrogen oxide control, and increase costs.

• Training content: Comprehensive training should cover all key aspects, including precise measurement accuracy, understanding the DEF quality standard (ISO 22241), and adhering to appropriate maintenance procedures.
• Support from Guantong: Important suppliers like Guantong offer professional training courses, carefully designed to equip operators with the necessary knowledge and skills to direct the operation of SCR systems.
• Benefits: It reduces human errors, significantly enhances the reliability of the entire system, with an estimated increase of 10%, and ensures consistent compliance.
• Note: Establish regular operator training courses, preferably under the continuous guidance of the SCR system supplier, to keep employees up-to-date with best practices and new technologies.

Conclusion

Diesel exhaust fluid (DEF) is indispensable for optimizing NOx reduction. It enables up to 90% emission cuts through strategies like precise metering, high-quality DEF, and urea pyrolysis. Guantong’s SCR technology and CFD simulation deliver tailored solutions for industrial compliance. Contact Guantong today for a tailored, source-to-solution SCR system. This will boost your facility’s efficiency and ensure compliance.