On-line monitoring device for nitrogen oxides of SCR denitration reactor of coal-fired power plant

The utility model provides a nitrogen oxide online monitoring device for an SCR denitration reactor of a coal-fired power plant. The device comprises an SCR denitration reactor, an outlet NOx collection probe, an inlet NOx collection probe, a flue gas collection data transmission channel, a flue gas analyzer, an outlet/inlet NOx collection probe switcher, a flue different-section collection pointswitcher, a flue different-depth collection point switcher, an instruction switching device and a switcher instruction transmission channel. The SCR denitration reactor is provided with an outlet NOxacquisition probe and an inlet NOx acquisition probe; and the acquisition probe is connected with the flue gas analyzer through a flue gas acquisition data transmission channel and an acquisition point switcher. The whole collection and analysis process involved in the utility model is online treatment, the NOx concentration at the inlet and the NOx concentration at the outlet of the SCR denitration reactor can be effectiv