Low-phosphorus corrosion inhibitor for sea water desalinization first-level reverse osmosis producing water

Abstract

The invention relates to a low-phosphorus corrosion inhibitor for sea water desalinization first-level reverse osmosis producing water. One liter of low-phosphorus corrosion inhibitor is prepared from 3 to 10 milligrams of sodium silicate (based on silicon dioxide (SiO2)), 5 to 15 milligrams of sodium hexametaphosphate, 2 to 4 milligrams of zinc sulfate (based on zinc ion (Zn<2+>)), 2 to 4 milligrams of benzotriazole or methyl benzotriazole and 60 to 100 milligrams of sodium hydroxide. By the low-phosphorus corrosion inhibitor, the corrosion rates of the metal materials commonly used in a heat-engine plant, such as carbon steel, red copper and the like in the sea water desalinization first-level reverse osmosis producing water are reduced from 1.14007 mm / a to 0.02067 mm / a and from 0.06173 mm / a to 0.00536 mm / a respectively; the corrosion inhibition rates of the low-phosphorus corrosion inhibitor on the carbon steel and the red copper are over 98 percent and 91 percent respectively; the corrosive action of the first-level reverse osmosis producing water on the materials is greatly relieved; and the metal surface pitting is completely inhibited, so that the service life of each of pipelines and equipment is greatly prolonged and the low-phosphorus corrosion inhibitor has almost no harm to the environment and is simple in subsequent treatment.

Description

technical field [0001] The invention relates to a low-phosphorus corrosion inhibitor in seawater desalination primary reverse osmosis product water, belonging to the technical field of seawater desalination. Background technique [0002] With the increasing shortage of water resources and the development of reverse osmosis technology, the use of reverse osmosis technology to obtain fresh water from seawater has been widely used in countries all over the world. Since the use of one-stage reverse osmosis can remove 99% of the salt in seawater, so that the salt content of the produced water is close to that of natural fresh water, thereby obtaining fresh water with use value, the method is economical and reliable. Therefore, one-stage reverse osmosis technology has become a solution The main source of water supply problems in coastal areas. As a large water user, thermal power plants consume a large amount of fresh water every year for equipment cooling, washing and other purp...

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Problems solved by technology

[0003] At the same time, the corrosion of metal materials in seawater desalination first-stage reverse osmosis production water has become increasingly prominent. The water distribution pipe network of many thermal power plant seawater desalination first-stage reverse osmosis projects has serious corrosion. Brownish yellow, there are a lot of corrosion products in the pipe, which not only seriously affects the water quality of the water supply, but also directly threatens the safety of the water distribution network, and even threatens the normal and efficient operation of the entire power plant

[0004] At present, at home and abroad, the method of adding alkalizing agents such as sodium hydroxide to adjust the pH value or adding calcium, magnesium, and carbonate ions is mainly used to slow down the corrosion effect of seawater desalination primary reverse osmosis water on metal materials. The operating cost is high, the effect is not good, and after introducing a large amount of hardness ions into the first-stage reverse osmosis product water of seawater desalination, there will be a scaling tendency in the subsequent pipeline, which is not suitable for popularization and application in thermal power plants

At present, there are also scholars (Liu Guangzhou, Wang Haitao, etc., a corrosion inhibitor for desalinated primary reverse osmosis water, publication number: CN101705489.A) for reference from the experience of circulating cooling water, using a high phosphate corrosion inhibitor formula to Slowing down the corrosion of carbon steel in primary reverse osmosis water has achieved a certain effect, but the high concentration of phosphate in this formula not only easily causes environmental problems such as eutrophication, but also because the polyphosphate in the formula is harmful to copper and Copper alloys are corrosive, and will corrode copper alloys such as copper that exist in the water distribution pipeline with carbon steel; moreover, this type of formula is easy to change color, making the solution with corrosion inhibitor easy to appear light yellow, and the visual effect is not good ; more importantly, this type of formula only relies on corrosion inhibitors for film protection. The results of dynamic coupons show that the pitting corrosion on the local surface of the metal cannot be completely suppressed in water with a high chloride ion content. There is obvious pitting phenomenon on the surface

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