High-temperature ammonia-spraying denitration spray gun for coal-fired boiler

The invention provides a high-temperature ammonia-spraying denitration spray gun for a coal-fired boiler, wherein the high-temperature ammonia-spraying denitration spray gun is simple in structure, reasonable in design, convenient to use and capable of being used under the high-temperature condition of a fuel-rich area. The spray gun comprises a spray gun barrel, a spray head arranged at one end of the spray gun barrel and a fixing assembly coaxially arranged at the other end of the spray gun barrel in a sleeving mode. The spray head is used for atomizing a reducing agent solution and then spraying the reducing agent solution into flue gas; the fixing assembly comprises a pipe base, a cooling air box and a sleeve. The inner side of the sleeve is coaxially sleeved on the spray gun barrel; one end of the cooling air box is fixedly connected with a pipe base. A cavity defined by the inner side of the cooling air box and the outer side of the sleeve serves as a cooling air chamber. An annular slit which is adjace