Corrosion inhibitor applied to SCAL type indirect cooling system and chemical adding method of corrosion inhibitor

Abstract

The invention belongs to the technical field of corrosion prevention of thermal power plant equipment, and particularly relates to a corrosion inhibitor applied to an SCAL type indirect cooling systemand a chemical adding method of the corrosion inhibitor. The chemical adding method comprises two steps of preparation of the corrosion inhibitor and addition of the corrosion inhibitor into the indirect cooling system. The corrosion inhibitor and the chemical adding method are characterized in that the corrosion inhibitor is prepared from sodium borate, sodium silicate, zinc sulfate, sodium tripolyphosphate, sodium hexametaphosphate, sodium molybdate, fatty alcohol-polyoxyethylene ether (penetrant) and desalted water in a chemical adding tank, and the corrosion inhibitor is injected into theSCAL type indirect cooling water system through a metering pump. The corrosion inhibitor and the chemical adding method have the beneficial effects that after the corrosion inhibitor is added into the SCAL type indirect cooling system, the corrosion rate of carbon steel in the SCAL type indirect cooling system can be controlled to be smaller than 0.075 mm / a, and the corrosion rate of pure aluminum in the SCAL type indirect cooling system can be controlled to be smaller than 0.0075 mm / a; after the corrosion inhibitor is applied, the water quality control range of the system can be properly widened, and the water changing frequency is reduced; after the corrosion inhibitor forms a film, the shutdown corrosion rate of the system can be reduced; and the components of the corrosion inhibitor are environment-friendly and low in toxicity.

Description

technical field [0001] The invention relates to the field of material corrosion protection, in particular to a corrosion inhibitor applied to a SCAL type intercooling system and a dosing method thereof. Background technique [0002] In recent years, a large number of surface condenser aluminum radiator type (SCAL type) indirect air cooling units have been built and put into production in northern my country. The biggest feature of this type of indirect air cooling system is that it uses aluminum materials as radiators on a large scale and uses air The cooled circulating water absorbs the exhaust steam after the steam turbine does work. This new type of indirect cooling system poses new challenges to material corrosion protection: due to the coexistence of two metals with large chemical properties, carbon steel and aluminum, in the system, the alkaline water working condition suitable for carbon steel corrosion protection is not suitable. It is suitable for amphoteric aluminu...

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Problems solved by technology

Although the water exchange treatment can temporarily alleviate the deterioration of water quality, since the SCAL intercooling system generally contains nearly 10,000 tons of desalinated water, the desalinated water production capacity of the power plant limits the water exchange speed, so the purification effect of this method on the circulating water quality is not significant. Not ideal; there are still disadvantages such as high cost and waste of resources in water exchange treatment

The cation bed bypass treatment method can avoid the aggravation of aluminum corrosion caused by the pH increase of circulating water by exchanging metal cations in water, but it cannot fundamentally solve the corrosion problem of carbon steel equipment, nor can it remove corrosive anions in water

Compared with water change and bypass treatment, chemical dosing treatment has the advantages of low cost and water saving. However, according to the feedback from the power plant, after adding hydrazine to the circulating water of the intercooling system, the corrosion problem of carbon steel in the system is still serious, and the pH and conductivity are abnormal. The problem of rising cannot be solved, and the toxicity of hydrazine has also caused serious harm to the health of power plant operators

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