Closed-loop cooling systems are core equipment in industrial production, and their stable operation is directly related to production efficiency and equipment lifespan. However, scale deposition and metal corrosion, common problems in these systems, are key factors limiting their effectiveness. Corrosion and scale inhibitors, through complex chemical reactions, effectively address these two challenges, becoming essential for ensuring efficient system operation.
Scale deposition is a major risk in closed-loop cooling systems. Dissolved calcium and magnesium ions in the circulating water gradually concentrate as the water evaporates, forming a hard scale layer on the inner walls of pipes and heat exchanger surfaces. This deposit not only reduces heat transfer efficiency and increases equipment energy consumption, but can also cause localized overheating and damage. Corrosion and scale inhibitors effectively inhibit scale formation through chelation and crystal distortion mechanisms. The active groups in their molecular structure bind to calcium and magnesium ions to form soluble complexes, preventing the ions from crystallizing on metal surfaces. Furthermore, the inhibitors disrupt the normal growth of crystals such as calcium carbonate, keeping them in a microcrystalline state and discharged with the water flow, thereby maintaining system cleanliness.
Metal corrosion is also a significant concern. Dissolved oxygen, chloride ions, and acidic substances in circulating water can electrochemically react with metal equipment, leading to thinning of equipment walls, weakening of structural strength, and even leaks. Organic phosphonates, nitrites, and other ingredients in corrosion and scale inhibitors form a dense protective film on metal surfaces. This film possesses excellent adhesion and chemical stability, effectively isolating the corrosive medium from the metal substrate. By adjusting the film-forming mechanism, the inhibitors can achieve tailored protection for different materials, such as carbon steel, stainless steel, and copper alloys, significantly extending equipment life.
In closed systems, the application of corrosion and scale inhibitors must balance system characteristics with inhibitor performance. Because closed-circulation cooling systems feature minimal water loss and high concentration rates, the inhibitors must be resistant to high temperatures and concentration. For example, inhibitors formulated with organic phosphonic acid and polycarboxylic acid maintain stability at high temperatures, preventing degradation of the protective film. Furthermore, for refrigerants such as ethylene glycol and methanol, specialized inhibitors with strong compatibility must be selected to avoid chemical reactions that could weaken the protective effect.
The proper administration of chemical reagents directly impacts treatment effectiveness. Excessive dosage not only wastes chemical but can also cause side effects such as foaming and algae growth. Underdosage prevents the formation of a complete protective film, leading to increased localized corrosion. In practical applications, chemical dosage must be accurately calculated based on water quality analysis results, combined with system volume and circulation flow. Continuous or intermittent dosing ensures uniform distribution of chemical reagents throughout the system, maintaining a stable concentration range.
Continuous monitoring is crucial for ensuring treatment effectiveness. Regularly testing circulating water indicators such as pH, conductivity, and calcium hardness provides a timely overview of system operating status. If monitoring data deviate from control ranges, chemical dosage or chemical type should be adjusted promptly. For example, if algae and bacteria levels exceed the specified limit, non-oxidizing biocides can be used in conjunction with treatment to prevent biosludge from accelerating corrosion.
From an economic perspective, the use of corrosion and scale inhibitors can significantly reduce system operation and maintenance costs. By reducing increased energy consumption, equipment replacement frequency, and downtime caused by scale buildup, the overall benefits far outweigh the chemical investment costs. Furthermore, the promotion of environmentally friendly low-phosphorus or phosphorus-free agents not only meets water pollution prevention and control requirements but also reduces eutrophication caused by phosphorus emissions, achieving a win-win situation for both economic and environmental benefits.
Practical experience has demonstrated that the appropriate selection and standardized operation of corrosion and scale inhibitors can improve the heat exchange efficiency and extend the service life of closed-loop cooling systems. Successful application cases in industries such as steel, chemicals, and power generation have significantly improved system operational stability and extended maintenance cycles, fully demonstrating the indispensable role of corrosion and scale inhibitors in closed systems. With continued innovation in water treatment technology, corrosion and scale inhibitors will continue to develop towards greater efficiency and environmental friendliness, providing more reliable technical support for industrial production.
