Simple ammonia spraying device suitable for large coal-fired boiler

The invention provides a simple ammonia spraying device suitable for a large coal-fired boiler. The simple ammonia spraying device extends to the inside of a flue of a reaction window; n sets of vertical flue sections are longitudinally arranged. Each ammonia spraying device comprises an ammonia gas injection tube, an ammonia gas flow electric control valve, an ammonia gas spray nozzle, wear-resistant angle steel and a supporting plate, one end of the ammonia gas injection tube is connected with an ammonia gas manifold, the other end is a blind end, and the length is determined according to the flue section width s of a temperature window (close to the flue width s); the spacing between the centers of the adjacent ammonia gas injection tubes is 1/5L-1/2L. The outer end of each ammonia gas injection tube is connected with one ammonia gas flow electric control valve to control the flow of ammonia gas. The ammonia gas spray nozzle is formed on each ammonia gas injection tube, the spraying direction of each verti