A composite organic amine shutdown protection agent for power plant boiler was developed in this study. And the effects of its reaction temperature and concentration on the protective effects were investigated. Polarization curve method

wet and hot corrosion test

scanning electron microscopy

X-ray energy dispersive spectroscopy and X-ray diffraction were used to study its protection mechanism. The results showed that

when the concentration of complex organic amine was 100 mg/L

pH was 10.0

and the temperature was kept at 300 ℃ for 4 h

the surface film forming of carbon steel and passivation protection effects were the best. Under the action of complex organic amine molecules

the closely linked ultrafine Fe_3O_4 spherical particles generated on the surface of the carbon steel specimens. At the same time

the carbon steel specimens physically adsorbed part of organic amine molecules to form a dense protective film. This protective film significantly reduced its corrosion current density and the wet and hot corrosion speed

and then obviously improved its corrosion resistance. This composite organic amine agent was applied to the protection of a 1 000 MW supercritical direct air-cooled boiler during the shutdown period. A complete and dense protective film was formed on the internal surface of power plant thermal equipment

and its breakdown time in deaerator by the acid copper sulfate was greater than 35 seconds

which exhibited great corrosion resistance.