Construction method of SCR denitration precise ammonia spraying system of coal-fired unit

The invention discloses a construction method of an SCR (Selective Catalytic Reduction) denitration precise ammonia spraying system of a coal-fired unit, the constructed SCR denitration precise ammonia spraying system of the coal-fired unit for flexible peak regulation comprises an SCR denitration reactor, and an NOx concentration detector and an NOx and ammonia concentration detector are arranged at a flue gas inlet and a flue gas outlet of the SCR denitration reactor; the NOx concentration detector is used for detecting the NOx concentration at the inlet of the SCR denitration reactor; the NOx and ammonia concentration detector collects and stores the NOx concentration at the inlet of the SCR denitration reactor and the NOx and ammonia concentration at the outlet of the SCR denitration reactor; the initial prediction model of the NOx emission at the outlet of the SCR denitration reactor is established, and the modeling precision and universality of the initial prediction model are further improved by adopti