选择性催化还原(SCR)技术是通过还原剂（如NH₃）在适当的温度并有催化剂存在的条件下，把氮氧化物（NOX）转化为空气中天然含有的氮气和水，脱硝效率高达90%以上。由于SCR脱硝技术的成熟以及高的脱硝率，现已成为国际上烟气脱硝的主流技术。

Selective catalytic reduction(SCR)technology IS to use the reducing agent(such as NH3)and catalyst to transfer NOX into the nitrogen and water naturally existing in the air at the appropriate temperature．The denox efficiency is above 90％．Because of mature SCR denox technology and high denox efficiency，SCR technology has become the main international technology for flue gas dpnox.

电厂应用原理: