Metal Surface Corrosion Control Under Alternating Steam and Cooling Water
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Solution Overview
Problem
Conventional methods fail to sufficiently inhibit corrosion of metal components that alternately contact steam and cooling water, leading to corrosion product accumulation, heat transfer inhibition, and decreased production efficiency.
Innovation Solution
A method involving the addition of phosphorus compounds and/or zinc compounds to cooling water, and corrosion-resistant film forming substances like polyamines to steam, with a specific ratio of scale inhibitors, to form a protective film on metal surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If corrosion inhibitors are added to cooling water for metal components contacting steam and cooling water, then corrosion prevention is improved, but the inhibitors are diluted by steam and concentration decreases, reducing effectiveness
Solution Approach 1:
The invention divides the corrosion protection system into two separate segments: (1) corrosion inhibitors added to cooling water for the cooling water-side metal surfaces, and (2) corrosion-resistant film forming substances added to steam for the steam-side metal surfaces. This segmentation allows each substance to be optimized for its specific environment without being diluted or degraded by the other phase.
Solution Approach 2:
The invention introduces corrosion-resistant film forming substances as an intermediary layer on the steam-side metal surfaces. These substances form protective films that prevent direct contact between steam and metal, acting as a mediator that protects the metal from corrosion without requiring high concentrations of inhibitors in the cooling water.
2Reliability
If long-chain aliphatic amine is continuously added to form adsorbed film on metal surface, then corrosion prevention is improved, but the film peels off without continuous addition and the system becomes complex
Solution Approach 1:
The invention applies preliminary action by forming corrosion-resistant films on metal surfaces before corrosion occurs. The corrosion-resistant film forming substances are added to steam to pre-establish protective layers on steam-side surfaces, and phosphorus compounds or zinc compounds are added to cooling water to pre-establish protective layers on cooling water-side surfaces.
Solution Approach 2:
The invention changes the chemical parameters of the protective substances. Instead of using long-chain aliphatic amines that form easily peeled adsorbed films, the invention uses phosphorus compounds, zinc compounds, and corrosion-resistant film forming substances that form more stable, adherent protective films through chemical reactions or stronger adsorption mechanisms.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents corrosion in metal components exposed to alternating steam and cooling water, maintaining heat transfer efficiency and reducing maintenance needs.
Implementation Method 1
a phosphorus compound and/or a zinc compound is added to the cooling water and a corrosion-resistant film forming substance is added to the steam
Implementation Method 2
the long-chain aliphatic amine adsorbs to the metal surface via amino groups to form a dense film of monomolecular or multimolecular layers
Data Source
AI summary
Provided is a method for preventing corrosion of metal component in which cooling water and steam alternately contact, in which a phosphorus compound and/or a zinc compound is added to the cooling water and a corrosion-resistant film forming substance is added to the steam. The phosphorus compound is at least one of hexametaphosphoric acid, tripolyphosphoric acid, orthophosphoric acid, phosphonobutanetricarboxylic acid, hydroxyethylidene diphosphonic acid (HEDP), and aminotrimethylphosphonic acid.