Detailed Explanation of SNCR Technology

1. Basic Concept

SNCR (Selective Non-Catalytic Reduction) is a medium-to-high temperature flue gas denitrification technology that reduces nitrogen oxides (NOx) to nitrogen (N₂) and water (H₂O) by injecting reducing agents (ammonia water or urea solution) into high-temperature flue gas without using catalysts.

2. Working Principle

• Optimal reaction temperature window: 850-1100°C

• Main chemical reactions:

  • Using ammonia water (NH₃):

    $$4NO+4N{H}_3+O_2\to 4N_2+6H_{2}O$$

  • Using urea (CO(NH₂)₂):

    $$2CO(N{H}_2{)}_2+4NO+O_2\to 4N_2+2C{O}_2+4H_{2}O$$

3. System Components

1. Reducing agent preparation and storage system

   • Ammonia water (20-25% concentration) or urea solution (40-50% concentration)

2. Injection system

   • Atomizing lances

   • Compressed air system

3. Control system

   • Temperature monitoring

   • Flow control

4. Technical Characteristics

5. Typical Applications

• Coal-fired boilers

• Waste incinerators

• Cement kilns

• Glass melting furnaces

• Biomass boilers

6. Advantages and Disadvantages

Advantages:

• Simple system with low investment

• No catalyst required

• Easy maintenance

• Small footprint

Disadvantages:

• Relatively low denitrification efficiency

• Sensitive to temperature

• Ammonia slip issues

• Not suitable for low-temperature flue gas

7. Comparison with SCR Technology

8. Technology Development Trends

• Combined use with SCR (SNCR/SCR hybrid technology)

• Development of new reducing agents

• Optimization of intelligent control systems

• New additives to expand temperature window

9. Case Study

After implementing SNCR technology in a 300t/d waste incineration plant:

• NOx emissions reduced from 350mg/m³ to 150mg/m³

• Operating costs 40% lower compared to SCR solution

• System operation rate exceeding 98%

10. Conclusion

SNCR technology is an economical and practical medium-to-high temperature flue gas denitrification solution, particularly suitable for small and medium-sized industrial boilers and specific industrial furnaces. Although its denitrification efficiency is lower than SCR, its low investment and simple system give it significant advantages in specific applications. With advancements in control technology, SNCR will see broader applications in the future.