The selective non-catalytic reduction(SNCR) denitrification system for coal-fired power plants and its working principle have been briefly presented.Taking the SNCR denitrification system in one power plant as example

the causes leading to common problems occurred frequently in practical operation

such as non-uniform distribution of ammonia

corrosion of water-sprayins holes

scaling in spraying nozzles

and bad atomization of spray guns etc.

have been analysed

and counter measures

such as adding steam agitation system

changing work condition of the carbamide-spraying guns

adopting desalted water as the diluent water

and ensuring the pressure of atomizing steam etc.

being given.