A circulating liquid for mechanical draft cooling tower and a preparation method thereof

Abstract

This invention belongs to the field of circulating fluid technology, specifically relating to a circulating fluid for mechanical ventilation cooling towers and its preparation method. The circulating fluid for mechanical ventilation cooling towers comprises the following components in parts by weight: 20-40 parts antifreeze, 3-8 parts corrosion inhibitor, 1-5 parts scale inhibitor, 0.5-3 parts bactericidal inhibitor, 0.08-1.48 parts pH adjuster, 0.002-0.006 parts defoamer, and 60-90 parts deionized water; the corrosion inhibitor is a phosphonocarboxylic acid copolymer. The circulating fluid provided by this invention can simultaneously achieve excellent corrosion inhibition and scale inhibition rates, meeting the requirements for long-term stable operation of mechanical ventilation cooling towers.

Description

Technical Field

[0001] This invention belongs to the field of circulating fluid technology, specifically relating to a circulating fluid for mechanical ventilation cooling towers and its preparation method. Background Technology

[0002] The central air conditioning cooling tower is the core heat dissipation component of the central air conditioning system. It achieves cooling and recycling of cooling water through water circulation and evaporation. The specific working principle is as follows: hot water in the system is evenly sprayed onto the surface of the heat dissipation material, and sensible heat exchange and evaporative heat dissipation are completed by air flow. The cooled water is pumped back to the heat exchanger for recycling. This can significantly reduce the operating cost of the central air conditioning system and improve the water resource utilization rate.

[0003] In the circulation system of a central air conditioning cooling tower, the performance of the circulating fluid directly determines the tower's operational stability, heat exchange efficiency, and equipment lifespan. Scale inhibitors are an indispensable component of the circulating fluid, their core function being to prevent scale formation. The active groups in the scale inhibitor molecules form stable chelates with calcium and magnesium ions in deionized water, preventing them from combining with carbonate ions to form insoluble precipitates such as calcium carbonate. Simultaneously, they adsorb onto the surface of scale microcrystals, inhibiting crystal growth and maintaining a dispersed state, thus preventing scale deposition on the heat exchanger tube walls and cooling tower packing surfaces. Furthermore, scale inhibitors can also help mitigate equipment corrosion to some extent, reducing the risk of equipment damage caused by under-scale corrosion, indirectly extending the service life of the cooling tower and its associated piping and heat exchangers, and lowering equipment maintenance costs.

[0004] However, current scale inhibitors used in mechanical ventilation cooling tower circulating fluids still have significant technical shortcomings. During repeated circulation, the water temperature in central air conditioning cooling tower circulating water continuously rises, and water evaporates continuously, leading to the concentration of soluble substances in the water. Simultaneously, it is susceptible to environmental pollution, easily resulting in deposit adhesion and equipment corrosion. This places high demands on the comprehensive performance of scale inhibitors. Existing scale inhibitors are mostly single-component or simple compound systems, making it difficult to meet the synergistic effects of various components in the circulating fluid. They generally fail to simultaneously achieve ideal corrosion inhibition and scale inhibition rates: some scale inhibitors, while achieving good scale inhibition effects, lack sufficient corrosion inhibition performance, failing to effectively suppress corrosion of metal equipment, leading to excessive corrosion rates and shortened equipment lifespan; others prioritize improving corrosion inhibition effects but sacrifice scale inhibition performance, making it easy for scale deposits to form in the circulating system, clogging heat dissipation channels, reducing heat exchange efficiency, and thus increasing the energy consumption of the central air conditioning system, contradicting the original intention of recycling and energy conservation.

[0005] Therefore, developing a circulating fluid that can simultaneously achieve excellent corrosion inhibition and scale inhibition rates, and meet the long-term stable operation requirements of mechanical ventilation cooling towers, as well as its preparation method, has become an urgent technical problem to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide a circulating fluid for mechanical ventilation cooling towers and its preparation method, which can simultaneously achieve excellent corrosion inhibition rate and scale inhibition rate, and can meet the requirements of long-term stable operation of mechanical ventilation cooling towers.

[0007] To achieve the above objectives, the present invention provides the following technical solution: A circulating fluid for a mechanical ventilation cooling tower comprises the following components in parts by weight: 20-40 parts antifreeze, 3-8 parts corrosion inhibitor, 1-5 parts scale inhibitor, 0.5-3 parts bactericidal inhibitor, 0.08-1.48 parts pH adjuster, 0.002-0.006 parts defoamer, and 60-90 parts deionized water.

[0008] The antifreeze is sodium formate.

[0009] The corrosion inhibitor is a phosphonocarboxylic acid copolymer.

[0010] The preparation method of the phosphonoacylcarboxylic acid copolymer includes the following steps: (1) Add ethylenediamine and deionized water to the reaction vessel, stir to dissolve, cool, add phosphorus trichloride dropwise, add formaldehyde aqueous solution dropwise, after the addition is complete, raise the temperature to 80-100℃, keep the temperature for 2-4 hours, cool, adjust the pH to obtain the reaction solution; (2) Mix acrylic acid, maleic anhydride and 2-acrylamide-2-methylpropanesulfonic acid, add deionized water, adjust pH to obtain mixed monomer solution; prepare initiator aqueous solution; under nitrogen atmosphere, add initiator aqueous solution and mixed monomer solution dropwise to reaction solution, keep warm and react; after reaction, cool to room temperature, adjust pH, adjust solid content to obtain phosphonocarboxylic acid copolymer.

[0011] The conditions for the heat preservation reaction in step (2) are: heat preservation reaction at 85-90℃ for 2-4 hours.

[0012] Traditionally, corrosion inhibitors in circulating fluids often employ ethylenediaminetetramethylenephosphonic acid (EDTA), or a combination thereof with methylbenzotriazole or mercaptobenzothiazole sodium. While EDTA possesses both corrosion inhibition and scale inhibition capabilities, its simple molecular structure limits its ability to form an adsorption film on metal surfaces via phosphonic acid groups, resulting in limited corrosion inhibition efficiency and making it difficult to simultaneously meet the requirements for excellent corrosion inhibition and scale dispersion. This invention provides a self-made phosphonocarboxylic acid copolymer corrosion inhibitor. The phosphonic acid groups in the copolymer are firmly adsorbed onto the metal surface to form a protective film. The carboxylic acid and sulfonic acid groups enhance the complexation and dispersion capabilities for scale-forming ions such as calcium and magnesium. Simultaneously, the three-dimensional structure of the polymer chain makes the protective film denser and more resistant to erosion. The sulfonic acid groups in the copolymer exhibit a certain complexation effect on copper ions, achieving comprehensive and synergistic protection for carbon steel. The copolymer's excellent dispersion properties also enable it to inhibit scale formation, reducing the burden on scale inhibitors and achieving a dual enhancement of corrosion inhibition and scale inhibition functions.

[0013] This invention synthesizes phosphonocarboxylic acid copolymers in the same reactor using a two-step method: Step 1: Ethylenediamine, formaldehyde, and phosphorus trichloride undergo a Mannich reaction to generate an EDTMP intermediate containing four phosphonic acid groups. Step 2: Acrylic acid, maleic anhydride, and 2-acrylamido-2-methylpropanesulfonic acid are introduced, and free radical copolymerization occurs under the action of an initiator. Under a nitrogen atmosphere, ammonium persulfate decomposes to generate free radicals, initiating a free radical copolymerization reaction of the double bonds in the mixed monomers. Simultaneously, the mixed monomers copolymerize with the phosphonic intermediate from the first stage, introducing phosphonoacrylic, carboxyl, and sulfonic acid groups into the copolymer molecular chain; thus, the EDTMP molecular chain combines with the polymer chain to form a phosphonocarboxylic acid copolymer with both chelating and dispersing functions.

[0014] The scale inhibitors include HT-801, a high-efficiency corrosion and scale inhibitor with a mass ratio of (0.8-1.0):(0.4-0.6), and HT-805, an environmentally friendly phosphorus-free corrosion and scale inhibitor. Shandong Huatai Water Treatment Technology Co., Ltd.

[0015] In traditional scale inhibitor formulations, ethylenediaminetetramethylenephosphonic acid is often used simultaneously as both a corrosion inhibitor and a scale inhibitor, resulting in overlapping functions and difficulty in achieving both. The corrosion inhibitor in this invention is a self-made phosphonocarboxylic acid copolymer, providing highly efficient corrosion inhibition. The scale inhibitor is a combination of two commercially available products: the highly efficient corrosion and scale inhibitor HT-801 and the environmentally friendly phosphorus-free corrosion and scale inhibitor HT-805. HT-801, through the synergistic effect of its organophosphorus carboxylic acid and sulfonate copolymer, exhibits excellent chelating and dispersing ability for calcium carbonate, calcium sulfate, and calcium phosphate scale. HT-805, on the other hand, complexes calcium, magnesium, and copper ions through a large number of carboxyl, hydroxyl, and ether groups. The self-made phosphonocarboxylic acid copolymer forms a triple synergistic mechanism with HT-801 and HT-805. The phosphonic acid groups of the copolymer and the organophosphorus compounds of HT-801 jointly enhance the protective film on the metal surface. The carboxylic acid / sulfonic acid groups of the copolymer, together with the polycarboxylic acid of HT-801 and the hydroxyl / ether groups of HT-805, form a three-dimensional dispersion network to prevent the deposition of scale particles. This invention achieves simultaneous improvement in corrosion inhibition efficiency and scale inhibition efficiency, and the components have good compatibility.

[0016] The bactericidal inhibitor is dodecyl dimethyl benzyl ammonium chloride.

[0017] The pH adjuster is selected from at least one of sodium hydroxide and sodium bicarbonate, and is used to adjust the pH value of the system to 8.5-11 to enhance the anti-corrosion effect.

[0018] The defoamer is a polyether or organosilicon, used to reduce the impact of air bubbles on heat exchange efficiency during the central air conditioning circulation process.

[0019] The method for preparing circulating fluid for mechanical ventilation cooling towers includes the following steps: mixing antifreeze, corrosion inhibitor, scale inhibitor, bactericide inhibitor, pH adjuster, defoamer and deionized water evenly to obtain circulating fluid for mechanical ventilation cooling towers.

[0020] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: 1. This invention provides a self-made phosphonocarboxylic acid copolymer corrosion inhibitor. The phosphonic acid groups in the copolymer are firmly adsorbed onto the metal surface to form a protective film. The carboxylic acid groups and sulfonic acid groups enhance the complexation and dispersion ability of scale-forming ions such as calcium and magnesium. At the same time, the three-dimensional structure of the polymer chain makes the protective film denser and more resistant to erosion. The sulfonic acid groups in the copolymer have a certain complexation effect on copper ions, achieving comprehensive and synergistic protection for carbon steel. The excellent dispersion performance of the copolymer itself also enables it to inhibit scale formation, reducing the burden on scale inhibitors and achieving a dual function of corrosion inhibition and scale inhibition.

[0021] 2. The corrosion inhibitor of this invention is provided by a self-made phosphonocarboxylic acid copolymer, which provides high-efficiency corrosion inhibition performance. The scale inhibitor is a compound of two commercially available special products: high-efficiency corrosion and scale inhibitor HT-801 and environmentally friendly phosphorus-free corrosion and scale inhibitor HT-805. The self-made phosphonocarboxylic acid copolymer forms a synergistic effect with HT-801 and HT-805. The phosphonic acid groups of the copolymer and the organophosphorus of HT-801 jointly enhance the protective film on the metal surface. The carboxylic acid / sulfonic acid groups of the copolymer, the polycarboxylic acid of HT-801, and the hydroxyl / ether groups of HT-805 together form a three-dimensional dispersion network to prevent scale particle deposition. This invention achieves simultaneous improvement in corrosion inhibition efficiency and scale inhibition efficiency, and the components have good compatibility. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] All raw materials used in the following embodiments of the present invention are commercially available products: High-efficiency corrosion and scale inhibitor HT-801 and environmentally friendly phosphorus-free corrosion and scale inhibitor HT-805. Shandong Huatai Water Treatment Technology Co., Ltd.

[0024] The defoamer is a polyether defoamer, model CI368, manufactured by Guangdong Nanhui New Materials Co., Ltd. Example 1

[0025] This embodiment provides a circulating fluid for a mechanical ventilation cooling tower, comprising the following components in parts by weight: 34 parts antifreeze, 5 parts corrosion inhibitor, 4 parts scale inhibitor, 1 part bactericidal inhibitor, 0.1 parts pH adjuster, 0.004 parts defoamer, and 70 parts deionized water.

[0026] The scale inhibitor comprises a high-efficiency corrosion and scale inhibitor HT-801 and an environmentally friendly phosphorus-free corrosion and scale inhibitor HT-805, with a mass ratio of 1:0.5. The antifreeze is sodium formate. The bactericidal inhibitor is dodecyl dimethyl benzyl ammonium chloride. The pH adjuster is sodium hydroxide.

[0027] The corrosion inhibitor is a phosphonocarboxylic acid copolymer, and the preparation method of the phosphonocarboxylic acid copolymer includes the following steps: (1) Add 60g of ethylenediamine and 120g of deionized water to the reaction vessel, stir to dissolve, cool to 15°C, slowly add 250g of phosphorus trichloride, control the adding rate so that the temperature does not exceed 40°C, after the addition is complete, slowly add 350g of formaldehyde aqueous solution with a concentration of 37wt%, control the temperature at 50°C, after the addition is complete, raise the temperature to 95°C, keep the temperature for reaction 3, cool to 50°C, add 30wt% sodium hydroxide aqueous solution, adjust the pH to 5, and obtain the reaction solution.

[0028] (2) Mix 260g acrylic acid, 180g maleic anhydride and 210g 2-acrylamide-2-methylpropanesulfonic acid, add 150g deionized water, and add 30wt% sodium hydroxide aqueous solution dropwise while stirring. Control the temperature at 35℃ and adjust the pH to 6 to completely hydrolyze the maleic anhydride to obtain a mixed monomer solution. Weigh 4% of the total mass of ammonium persulfate and add deionized water to prepare an initiator aqueous solution with a concentration of 8wt%. Under a nitrogen atmosphere, add the initiator aqueous solution and the mixed monomer solution dropwise to the first stage reaction solution simultaneously, maintain the stirring speed at 300rpm, and add for 1.5h. After the addition is completed, keep the reaction at 90℃ for 3h. After the reaction is completed, cool to room temperature, adjust the final pH to 7.0 with 30wt% sodium hydroxide aqueous solution, add deionized water, and adjust the solid content of the product to 40wt% to obtain a phosphonocarboxylic acid copolymer.

[0029] The method for preparing circulating fluid for mechanical ventilation cooling towers includes the following steps: mixing antifreeze, corrosion inhibitor, scale inhibitor, bactericide inhibitor, pH adjuster, defoamer and deionized water evenly to obtain circulating fluid for mechanical ventilation cooling towers. Example 2

[0030] This embodiment provides a circulating fluid for a mechanical ventilation cooling tower, comprising the following components in parts by weight: 40 parts antifreeze, 8 parts corrosion inhibitor, 5 parts scale inhibitor, 3 parts bactericidal inhibitor, 1.48 parts pH adjuster, 0.006 parts defoamer, and 90 parts deionized water.

[0031] The scale inhibitor comprises a high-efficiency corrosion and scale inhibitor HT-801 (mass ratio 0.9:0.5) and an environmentally friendly phosphorus-free corrosion and scale inhibitor HT-805. The antifreeze is sodium formate. The bactericidal inhibitor is dodecyl dimethyl benzyl ammonium chloride. The pH adjuster is sodium hydroxide.

[0032] The corrosion inhibitor is a phosphonocarboxylic acid copolymer, and the preparation method of the phosphonocarboxylic acid copolymer includes the following steps: (1) Add 60g of ethylenediamine and 120g of deionized water to the reaction vessel, stir to dissolve, cool to 15°C, slowly add 250g of phosphorus trichloride, control the adding rate so that the temperature does not exceed 40°C, after the addition is complete, slowly add 350g of formaldehyde aqueous solution with a concentration of 37wt%, control the temperature at 50°C, after the addition is complete, raise the temperature to 95°C, keep the temperature for reaction 3, cool to 50°C, add 30wt% sodium hydroxide aqueous solution, adjust the pH to 5, and obtain the reaction solution.

[0033] (2) Mix 260g acrylic acid, 180g maleic anhydride and 210g 2-acrylamide-2-methylpropanesulfonic acid, add 150g deionized water, and add 30wt% sodium hydroxide aqueous solution dropwise while stirring. Control the temperature at 35℃ and adjust the pH to 6 to completely hydrolyze the maleic anhydride to obtain a mixed monomer solution. Weigh 4% of the total mass of ammonium persulfate and add deionized water to prepare an initiator aqueous solution with a concentration of 8wt%. Under a nitrogen atmosphere, add the initiator aqueous solution and the mixed monomer solution dropwise to the first stage reaction solution simultaneously, maintain the stirring speed at 300rpm, and add for 1.5h. After the addition is completed, keep the reaction at 90℃ for 3h. After the reaction is completed, cool to room temperature, adjust the final pH to 7.0 with 30wt% sodium hydroxide aqueous solution, add deionized water, and adjust the solid content of the product to 40wt% to obtain a phosphonocarboxylic acid copolymer.

[0034] The method for preparing circulating fluid for mechanical ventilation cooling towers includes the following steps: mixing antifreeze, corrosion inhibitor, scale inhibitor, bactericide inhibitor, pH adjuster, defoamer and deionized water evenly to obtain circulating fluid for mechanical ventilation cooling towers.

[0035] Comparative Example 1 The difference between this comparative example and Example 1 is that the corrosion inhibitor is ethylenediaminetetramethylenephosphonic acid.

[0036] Comparative Example 2 The difference between this comparative example and Example 1 is that the corrosion inhibitor is ethylenediaminetetramethylenephosphonic acid, methylbenzotriazole and mercaptobenzothiazole sodium in a mass ratio of 1:0.6:0.3.

[0037] Comparative Example 3 The difference between this comparative example and Example 1 is that the scale inhibitor is ethylenediaminetetramethylenephosphonic acid.

[0038] Comparative Example 4 The difference between this comparative example and Example 1 is that the scale inhibitor is a high-efficiency corrosion and scale inhibitor HT-801.

[0039] Comparative Example 5 The difference between this comparative example and Example 1 is that the scale inhibitor includes a high-efficiency corrosion and scale inhibitor HT-801 with a mass ratio of 1.0:1.0 and an environmentally friendly phosphorus-free corrosion and scale inhibitor HT-805.

[0040] Comparative Example 6 The difference between this comparative example and Example 1 is that the scale inhibitor includes the high-efficiency corrosion and scale inhibitor HT-801 with a mass ratio of 1.0:0.2 and the environmentally friendly phosphorus-free corrosion and scale inhibitor HT-805.

[0041] Performance testing The performance of the circulating fluids in Examples 1-2 and Comparative Examples 1-6 was tested. The carbon steel test pieces were 20# steel with dimensions of 50mm×25mm×2mm. 1. Corrosion inhibition performance: In accordance with GB / T18175-2014, the corrosion inhibition performance was tested using a rotating plate corrosion apparatus at a temperature of 45°C and a rotation speed of 75 r / min.

[0042] 2. Scale inhibition performance: The scale inhibition performance was determined by the calcium carbonate deposition method, referring to GB / T / 16632-2019.

[0043] The water parameters used are: pH 6.9, conductivity 137 μs / L, total hardness (as CaCO3) 47 mg / L, total alkalinity (as CaCO3) 23 mg / L, and chloride ion concentration (Cl). - 18 mg / L. In actual cooling tower operation, water continuously evaporates, and dissolved salts continuously accumulate. Significant scaling or corrosion risk only appears when the concentration factor reaches a certain value (usually 3-8 times). The experimental water prepared in this experiment had a concentration factor of 6: pH 7.8, total hardness (as CaCO3) 282 mg / L, and total alkalinity (as CaCO3) 138 mg / L.

[0044] The performance test results are shown in Table 1.

[0045] Table 1 Corrosion rate (mm / a) Scale inhibition rate % Example 1 0.022 98 Example 2 0.027 97 Comparative Example 1 0.042 90 Comparative Example 2 0.038 92 Comparative Example 3 0.036 85 Comparative Example 4 0.035 87 Comparative Example 5 0.032 91 Comparative Example 6 0.031 93 As shown in Table 1, the circulating fluids of Examples 1-2 can simultaneously achieve excellent corrosion inhibition and scale inhibition rates. This indicates that the present invention, by using a self-made phosphonocarboxylic acid copolymer as a corrosion inhibitor and compounding it with a specific ratio of HT-801 and HT-805 scale inhibitors, achieves a simultaneous and synergistic improvement in corrosion inhibition and scale inhibition performance.

[0046] Comparative Example 1 uses a single corrosion inhibitor commonly used in existing technologies, resulting in a worse overall effect.

[0047] Comparative Example 2 uses a compound corrosion inhibitor commonly used in the prior art. Although it is an improvement compared to a single corrosion inhibitor, the effect is still worse than that of Example 1.

[0048] In Comparative Example 3, the scale inhibitor used was ethylenediaminetetramethylenephosphonic acid, but it was still impossible to achieve both excellent corrosion inhibition rate and scale inhibition rate.

[0049] Comparative Examples 4-6 illustrate that only a specific ratio of two commercially available scale inhibitors can achieve both excellent corrosion inhibition and scale inhibition rates.

[0050] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A circulating fluid for a mechanical ventilation cooling tower, characterized in that, The product comprises the following components in parts by weight: 20-40 parts antifreeze, 3-8 parts corrosion inhibitor, 1-5 parts scale inhibitor, 0.5-3 parts bactericidal inhibitor, 0.08-1.48 parts pH adjuster, 0.002-0.006 parts defoamer, and 60-90 parts deionized water; wherein the corrosion inhibitor is a phosphonocarboxylic acid copolymer.

2. The circulating fluid for a mechanical ventilation cooling tower according to claim 1, characterized in that, The preparation method of phosphonoacylcarboxylic acid copolymer includes the following steps: (1) Add ethylenediamine and deionized water to the reaction vessel, stir to dissolve, cool, add phosphorus trichloride dropwise, add formaldehyde aqueous solution dropwise, after the addition is complete, raise the temperature to 80-100℃, keep the temperature for 2-4 hours, cool, adjust the pH to obtain the reaction solution; (2) Mix acrylic acid, maleic anhydride and 2-acrylamide-2-methylpropanesulfonic acid, add deionized water, adjust pH to obtain mixed monomer solution; prepare initiator aqueous solution; under nitrogen atmosphere, add initiator aqueous solution and mixed monomer solution dropwise to reaction solution, keep warm and react; after reaction, cool to room temperature, adjust pH, adjust solid content to obtain phosphonocarboxylic acid copolymer.

3. The circulating fluid for a mechanical ventilation cooling tower according to claim 2, characterized in that, The conditions for the heat preservation reaction in step (2) are: heat preservation reaction at 85-90℃ for 2-4 hours.

4. The circulating fluid for a mechanical ventilation cooling tower according to claim 1, characterized in that, The antifreeze is sodium formate.

5. The circulating fluid for a mechanical ventilation cooling tower according to claim 1, characterized in that, The scale inhibitors include the high-efficiency corrosion and scale inhibitor HT-801 and the environmentally friendly phosphorus-free corrosion and scale inhibitor HT-805.

6. The circulating fluid for a mechanical ventilation cooling tower according to claim 5, characterized in that, The scale inhibitors include HT-801, a high-efficiency corrosion and scale inhibitor with a mass ratio of (0.8-1.0):(0.4-0.6), and HT-805, an environmentally friendly phosphorus-free corrosion and scale inhibitor.

7. The circulating fluid for a mechanical ventilation cooling tower according to claim 1, characterized in that, The bactericidal inhibitor is dodecyl dimethyl benzyl ammonium chloride.

8. The circulating fluid for a mechanical ventilation cooling tower according to claim 1, characterized in that, The pH adjuster is selected from at least one of sodium hydroxide and sodium bicarbonate.

9. The circulating fluid for a mechanical ventilation cooling tower according to claim 1, characterized in that, The defoamer is a polyether defoamer or an organosilicon defoamer.

10. A method for preparing circulating fluid for a mechanical ventilation cooling tower according to any one of claims 1-9, characterized in that, The process includes the following steps: mixing antifreeze, corrosion inhibitor, scale inhibitor, bactericide inhibitor, pH adjuster, defoamer and deionized water evenly to obtain circulating fluid for mechanical ventilation cooling towers.