May 17, 2023
排ガス脱硝SCRとSNCR技術の比較
The boiler burns low calorific value and high ash fuel, and the tail ash concentration is much higher than that of pulverized coal boiler, which will cause serious wear and lower service life of SCR reactor catalyst, and will increase the operating cost; the flue gas temperature after the coal saver is lower than that of pulverized coal furnace, and the design of 310℃ is the lower temperature limit of SCR denitrification reaction, which is not conducive to the SCR reactor to improve denitrification efficiency; as the catalyst will oxidize SO2 to SO3 and reacts with fugitive ammonia to produce ammonia sulfate and ammonium hydrogen sulfate, which will easily cause ash accumulation and corrosion in the air preheater and increase the system resistance, affecting the safety of unit operation. In view of the above factors, SCR or combined SNCR+SCR denitrification process is not considered. Selection of denitrification process Comparison of flue gas denitrification technologies (Fujian region) SNCRはCFBユニットに適しています。第一に、その炉出口温度は一般に850〜-1000℃の範囲内であり、SNCRプロセスの効率的な「温度ウィンドウ」内にあります。第二に、燃焼後の煙道ガスは分離器を通過するために3つのストランドに分割され、分離器内で激しく混合され、滞留時間は1.5秒以上です。また、滞留時間は 1.5 秒以上であり、SNCR プロセスに自然で優れた反応器を提供します。最後に、CFB燃焼技術は低NOX燃焼技術であるため、CFBボイラー出口のNOX濃度は低く、SNCRプロセスを通じて出口濃度は環境保護要件を保証できます。さらに、SNCRプロセスの投資と運用コストはSCRプロセスよりも低く、産業試験と海外での運転経験はすべて、SNCRシステムがCFBボイラーに使用されることを示しています。さらに、SNCRプロセスの投資と運用コストはSCRプロセスよりも低く、工業試験と海外での運用経験により、SNCRシステムは合理的な設計と50%以上の脱硝効率を備えたCFBボイラーで使用でき、アンモニアの流出はSCRプロセスよりも少ないことが示されています。 8ppm。 Compared with SCR denitrification technology, SNCR denitrification technology has the advantages of simple and easy implementation, low investment and operation cost, small footprint, short construction period, and NOx emission can be reduced. The construction period is short, and the NOx emission can meet the environmental protection requirements. According to meet the layout requirements, the investment cost is economical and reasonable, and the SNCR process is recommended for this project. 2. SNCR denitrification system reductant selection SNCR denitrification system reducing agents are liquid ammonia, ammonia and urea. 1) Liquid ammonia: Advantages: it will quickly evaporate into gas after spraying into the furnace chamber and will not cause wet wall and corrosion on the heated surface of the furnace; Disadvantages: ammonia is toxic, flammable and explosive, high safety protection requirements for storage, and requires approval from relevant fire safety departments for mass storage and use; SNCR using liquid ammonia is relatively complex system, high initial investment costs, high operation and maintenance costs, high pipeline losses, frequent liquid ammonia leakage accidents, and from the safety aspect, it is recommended not to use liquid ammonia as reducing agent; 2) Ammonia: Advantages: higher jet rigidity and penetration than ammonia jetting; Disadvantages: ammonia is malodorous, volatile and corrosive, has certain operational safety requirements, and has a complex storage and...
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