Corrosion Research Of Desalination For The Water Pipes And Facilities Of Nuclear Power Plants

Shortage of fresh water resources is a key problem restricting the development of human society.As a supplement of freshwater resources,seawater desalination has been more widely applied currently.However seawater desalination cause severe corrosion of associated facilities pipes.Because the lack of relevant research data,corrosion problems of water desalination system still not been effectively resolved.Corrosion and corrosion mechanism of 20 # steel,HSi80-3 brass,S304 stainless steel,ductile iron and galvanized steel in static,static pressure,low pressure scour states were evaluated by using corrosion weight loss,Tafel polarization curve,AC impedance and three-dimensional electron microscopy.The best solution to reduce the corrosive of seawater desalination was filtered out from different quenching programs,and the effect of the selected modulation scheme was evaluated.The main results are as follows:(1)In the static reverse osmosis means out water,the corrosion resistance of 20 # steel was grade 4-5,and it can be used to make static storage device,while the corrosion rate of HSi80-3 reached level 1.In the static pressure reverse osmosis means out water,corrosion rates of both 20 # steel and ductile iron were Level 5,which proposed to strengthen the corrosion protection.The corrosion rate of Galvanized steel was less than 0.05 mm / a,with good corrosion resistance.In reverse osmosis device with pressure flow out water,corrosion rate of 20 # steel was 5 to 6 levels,and corrosion protection treatment was recommended.Corrosion rate of S30408 reached level 1,corrosion does not occur basically.The corrosion rate of the same material in three test states were as follows: low pressure erosion-corrosion was the most serious,followed by static corrosion,static corrosion was the lightest.(2)By screening from modulation schemes of reverse osmosis device water: modulation scheme(0.3ppm NaClO+Ca(OH)2(pH was adjusted to 8.5))could effectively reduce the corrosive of reverse osmosis device water,and corrosion rate was about 20 to 30%.After modulation,the corrosion rate of these several metal were decreased in static,static pressure and erosion of reverse osmosis device out water,and the corrosion rate of 20 # steel and ductile iron did not exceed 5,copper alloy corrosion resistance was level 2 to level 3,ctainless steel basically maintained at level 1 to level 2,and they can be used as storage facilities of reverse osmosis device or transmission pipe.(3)20 # steel and ductile iron mostly rendered uniform dissolved morphology in the reverse osmosis device out water,part of samples surface localized corrosion.The corrosion rate of ductile iron was less than 20 # steel,and surface coating of galvanized steel may slow down the corrosion process of substrates to a certain extent,and substrate was slightly corrosive;HSi80-3 brass showed slightly surface corrosion and dezincification;S30408 showed almost no significant corrosion.(4)Electrochemical Corrosion Behavior Rules of these several materials in reverse osmosis device out water showed that: With the extension of immersion time,corrosion current density and charge transfer resistance of metallic materials varied not obvious,but corrosion current density and corrosion tends decreased since the surface passivation film of S30408 was formed.