SNCR stands for "Selective Non-Catalytic Reduction," which is a mature NOx control technology. Its working principle involves spraying ammonia water or urea, which contain amino groups, into the boiler furnace or cement kiln decomposition furnace at temperatures ranging from 850 to 1100℃. In this narrow temperature range, these amino-based reductants selectively react with NOx in the flue gas, producing harmless and non-polluting N2 and H2O. Under conditions where the operating cost of the reductant is appropriate and ammonia slip does not exceed 10 ppm, a denitrification efficiency of over 80% can generally be achieved.