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Ruthenium-iridium Titanium Electrode Electrolysis Treatment System for Air-conditioning Circulating Cooling Water

With the widespread use of air conditioners, more and more attention has been paid to the quality of air-conditioning circulating cooling water. The quality of cooling water directly affects the heat transfer performance inside the condenser. Under certain conditions of evaporation temperature and other conditions, the higher the condensation temperature The lower the cooling coefficient, the lower the power consumption and the more economical the unit operation. According to statistics, the power consumption per unit cooling capacity is reduced by about 3%-4% for every 1°C decrease in the condensing temperature. Therefore, ensuring that the circulating cooling water quality is within a certain range is one of the main measures to prevent the cooling efficiency of the refrigeration unit from declining.

Scale, bacteria and algae growth and corrosion problems will occur in the central air-conditioning cooling circulating water system. During the cooling period in summer, the cooling cycle is an open system. At the same time, organic matter and microorganisms in the air and dust will be brought into the water. The temperature of the cooling water is very suitable for the growth of bacteria and algae. The proliferation of bacteria such as heterooxobacteria, iron bacteria, nitrifying bacteria, and sulfate-reducing bacteria will cause corrosion of the inner wall of the pipeline, resulting in the shedding of rust, which affects the heat exchange of the condenser; Legionella and other bacteria will also grow in the circulating cooling water. Injury to the human body. The evaporation of water in the cooling tower gradually increases the salt content in the circulating water, and the carbon dioxide in the water is resolved and dissipated in the tower, which increases the tendency of calcium carbonate in the water to scale and precipitate on the heat transfer surface. The calcium and magnesium ions in the circulating water will adhere to the inner wall of the copper tube of the condenser, forming dense scale (mainly calcium carbonate scale).

Scale and fouling often combine together, and fouling and slime can cause or aggravate corrosion and seriously affect heat transfer. Therefore, the main task of cooling circulating water treatment is to eliminate or reduce the harm of scaling, corrosion and biological sludge, so as to ensure the efficiency and service life of the entire circulating water system. Because the scaling, corrosion and algae growth of the air-conditioning cooling water system are not formed in a short period of time, nor will they have a destructive effect on the system in a short period of time, they often do not get enough attention from the operation and management personnel. But "scaling, corrosion, bacteria and algae" are problems that cannot be ignored in the circulating cooling water system.

The characteristics of the water quality of the circulating cooling water of the central air conditioner: the concentration ratio is high in summer. Compared with the industrial circulating cooling water system, the ratio of the retained water to the circulating water in the circulating cooling water system of the air conditioner is very small. The concentration ratio will increase, and even the concentration ratio of some air-conditioning circulation systems will be as high as 10 times. The growth of microbial bacteria and algae is serious, and efficient sterilization measures and daily management are required to control the growth of microorganisms.

At present, most of the circulating cooling water systems of central air conditioners at home and abroad use the method of industrial circulating cooling water, that is, chemical dosing treatment methods, which include water treatment systems, dosing systems, cleaning systems, backwashing systems and sewage systems. The supplementary water of the system is ion-exchanged to remove hardness and salts combined with adding scale inhibitor, corrosion inhibitor and bactericidal and algaecide to the circulating water, and the system is regularly cleaned and backwashed, forming a complete set of water treatment technology.

However, since the ratio of the retained water to the circulating water in the air-conditioning circulating cooling water system is very small, the addition of scale inhibitors, bactericides and corrosion inhibitors will greatly increase the salts and organic matter in the water body, making the water quality more unstable and dissolved. A large number of chemical wastewater will have a certain impact on the environment. In view of the current situation of circulating cooling water in central air conditioning, Shaanxi Jinwoke Metal Materials Co., Ltd. has developed a new air conditioning cooling water treatment method by taking advantage of its own advantages: electrochemical Circulating cooling water treatment technology.

This technology uses the principle of electrolysis to remove scale, kill bacteria and alleviate corrosion, so as to achieve the purpose of circulating cooling water treatment. This technology has no chemical pollution, the operating cost is much lower than the chemical dosing method, and the maintenance cost is low, which is environmentally friendly. Friendly and keeps the system free from fouling.

The specific process of the system: the air-conditioning cooling water flows through the electrolysis reactor, insoluble precious metal electrodes are arranged in the electrolysis chamber, and the insoluble electrodes (cathode and anode) apply a DC current under a safe voltage to carry out the electrolysis reaction on the cooling water flowing through it, and the anode Two types of disinfection reactions take place on surfaces:

1. Anodic oxidation: the use of electrolysis to produce oxidizing substances such as ClO-, HClO3, H2O2, O3, OH- and other oxidizing substances to kill microorganisms and green algae, and the DC voltage of the electrode can also directly act on the microorganisms to kill them.

2. Acidic catalysis: According to the equation of water ionization H2ODH++OH-, the cooling water near the anode is acidic, while the cooling water near the cathode is alkaline. The acidic microenvironment will deactivate the microorganisms and green algae in the water body.

Since the cooling water near the cathode is obviously alkaline, the reaction will occur in the cathode area based on the high pH and small environment as follows:

Mg(HCO3)2 + 4OH- → Mg(OH)2↓ + 2H2O + 2CO3-2

Ca(HCO3)2 + 2OH- → CaCO3↓ + 2H2O + CO3-2

Mg(HCO3)2 → MgCO3↓ + 2H2O + CO2↑

(SiO2)aq → SiO2↓

In this process, the main components of scale, magnesium carbonate, calcium carbonate, magnesium hydroxide and silicon dioxide, are almost all captured and fixed by the cathode. Due to the scale formed on the surface of the cathode, the water quality of the cooling water system is gradually softened, so that the scale in the system gradually dissolves and falls off.

When the central air-conditioning cooling water system undergoes continuous electrolysis, due to the hydrogen evolution of the cathode and the escape of CO2 dissolved in the water, the pH value of the entire circulating water body will gradually increase, and the weakly alkaline water body will reduce the corrosion effect to the lowest level. .

Advantages of this system:

1. No chemical additional substances are generated;

2. Clean water bodies and inhibit the formation of microorganisms and green algae, destroy the growth environment of microorganisms and destroy biofilms;

3. Inhibit the formation of scale;

4. Remove the hidden danger of corrosion by creating an alkaline environment;

5. Automatic and continuous removal of suspended solids and scale;

6. Provide automatic operation equipment;

7. Save maintenance;

8. There is no need to transport, store and transport chemicals with potential safety hazards;

9. No environmental restrictions, harmless to the environment;

The system perfectly solves the three major problems of scaling, biological sludge and corrosion of the cooling water of the central air conditioner. This technology is also applicable to various circulating cooling water systems in the industry.