A degreasing agent for closed ethylene glycol process circulating water system

Abstract

The invention provides a degreasing agent for a closed ethylene glycol process circulating water system, which solves the problems that the existing closed ethylene glycol process circulating water system has a large amount of retained water and a high content of ethylene glycol in the water, such as 25%, 35%, 50%, etc. If the water is directly discharged and replaced with new ethylene glycol, the oily ethylene glycol water cannot be directly discharged to the environment, and cannot be directly discharged into a sewage pipe network to cause adverse effects on a sewage treatment system; at the same time, the ethylene glycol itself is expensive and will cause high economic losses to enterprises. The degreasing agent can be widely used in the field of closed ethylene glycol process circulating water systems; the degreasing agent specifically comprises the following components: 800-1500 mg / L of zinc dihydrogen phosphate or zinc gluconate, 1-5 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 1-5 mg / L of methylbenzotriazole, 0.1-1 mg / L of praseodymium nitrate, 5-10 mg / L of tripotassium phosphate, and 1-5 mg / L of potassium hydroxide.

Description

Technical Field

[0001] The invention belongs to the technical field of closed ethylene glycol process circulating water systems, and in particular relates to a degreasing agent for closed ethylene glycol process circulating water systems. Background Art

[0002] There are some closed ethylene glycol process circulating water systems on the production lines of manufacturing industries such as the pharmaceutical field. This type of system mainly utilizes the characteristic of ethylene glycol not freezing at low temperatures, so that the system water can store energy at low temperatures, and is connected to the production equipment system through a heat exchanger for heat exchange to cool the production equipment. The ethylene glycol content in this type of water system is often very high. The system medium of the production equipment is heat transfer oil. During the operation of this type of system, the heat transfer oil often leaks into the closed ethylene glycol process circulating water system due to heat exchange equipment failure and other reasons, and has already emulsified. Continuing to use it will cause safety operation hazards such as oil film adhesion to the heat exchange wall, affecting the heat exchange efficiency of the equipment and reducing the life of the equipment. The heat transfer oil has been emulsified in the water, there is no obvious oil-water stratification interface, and it is impossible to remove the oil by stratified oil separation and cleaning. At the same time, this type of system has a large amount of water, and the ethylene glycol content in the water is very high, such as 25%, 35%, 50%, etc. If it is directly discharged and replaced with new ethylene glycol, the oil-containing ethylene glycol water cannot be directly discharged, which will affect the environment, and it cannot be directly discharged into the sewage pipe network, which will have an adverse effect on the sewage treatment system. At the same time, ethylene glycol itself is expensive and will bring great economic losses to enterprises. Therefore, production enterprises are in urgent need of a cost-effective degreasing agent that can degrease the closed ethylene glycol circulating water system to solve the problem.

[0003] At present, there are many chemical formula agents used for oil removal in the petrochemical industry and wastewater treatment. A lot of oily wastewater will be produced during the mining and processing of the oil industry, and some open circulating cooling water systems also have the problem of oil leakage and infiltration. Existing oil removal agents are mostly inorganic aluminum iron and organic polymer and biological flocculants, short-chain alcohols, surfactants, polymer compounds and other demulsifiers, single varieties or compound formulas. Patent No. 200710019018.6 "A method and process flow for treating oilfield production wastewater" provides a drug for oil removal treatment of oilfield production wastewater and reinjection water to improve oil recovery. Patent No. 201510537151.5 "Composite flocculant, its preparation method and oilfield wastewater treatment method" provides a flocculant with both flocculation effect and demulsification performance, which is a drug for treating oilfield wastewater with a high degree of emulsification. Patent application number 201811276968.1 "A sewage treatment agent and its preparation method" provides a sewage treatment agent with flocculation properties that can effectively remove grease from sewage. The use of these agents with oil removal properties requires sedimentation tanks, filtration and other wastewater treatment processes to complete. This type of agent cannot be used for oil removal in closed ethylene glycol circulating water systems. Degreasing agents are also required when the open circulating cooling water in the petrochemical field has a high oil content in the water due to system leakage. After this type of circulating water degreasing agent is added to the cooling water for the oil removal reaction, the system water needs to be drained and replaced with new water to complete. This type of agent is also not suitable for oil removal in closed ethylene glycol circulating water systems. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the above-mentioned technology and provide a degreasing agent for a closed ethylene glycol process circulating water system.

[0005] To this end, the present invention provides a degreasing agent for a closed ethylene glycol process circulating water system, comprising the following components: 800-1500 mg / L of zinc dihydrogen phosphate or zinc gluconate, 1-5 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 1-5 mg / L of methylbenzotriazole, 0.1-1 mg / L of praseodymium nitrate, 5-10 mg / L of tripotassium phosphate, 0-1 mg / L of rose bengal, and 1-5 mg / L of potassium hydroxide.

[0006] Further, the components include 800 mg / L zinc dihydrogen phosphate or zinc gluconate, 1 mg / L magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid, 1 mg / L tolyltriazole, 0.1 mg / L praseodymium nitrate, 5 mg / L tripotassium phosphate, 0.1 mg / L rose bengal, 1 mg / L potassium hydroxide, and solvent water.

[0007] Further, the components include 1500 mg / L of zinc dihydrogen phosphate or zinc gluconate, 5 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid, 5 mg / L of methylbenzotriazole, 1 mg / L of praseodymium nitrate, 10 mg / L of tripotassium phosphate, 1 mg / L of rose bengal, 5 mg / L of potassium hydroxide, and solvent water.

[0008] Further, the components include 1000 mg / L zinc dihydrogen phosphate or zinc gluconate, 2 mg / L magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid, 2 mg / L tolyltriazole, 0.5 mg / L praseodymium nitrate, 8 mg / L tripotassium phosphate, 0.5 mg / L rose bengal, 3 mg / L potassium hydroxide, and solvent water.

[0009] Further, the components include 800 mg / L zinc dihydrogen phosphate or zinc gluconate, 5 mg / L magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid, 5 mg / L tolyltriazole, 1 mg / L praseodymium nitrate, 10 mg / L tripotassium phosphate, 1 mg / L rose bengal, 5 mg / L potassium hydroxide, and solvent water.

[0010] Further, the components include 1000 mg / L of zinc dihydrogen phosphate or zinc gluconate, 1 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid, 5 mg / L of methylbenzotriazole, 1 mg / L of praseodymium nitrate, 10 mg / L of tripotassium phosphate, 1 mg / L of rose bengal, 5 mg / L of potassium hydroxide, and solvent water.

[0011] Further, the components include 1500 mg / L of zinc dihydrogen phosphate or zinc gluconate, 2 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid, 3 mg / L of methylbenzotriazole, 0.3 mg / L of praseodymium nitrate, 7 mg / L of tripotassium phosphate, 0.3 mg / L of rose bengal, 3 mg / L of potassium hydroxide, and solvent water.

[0012] Further, the components include 900 mg / L zinc dihydrogen phosphate or zinc gluconate, 4 mg / L magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid, 4 mg / L tolyltriazole, 0.3 mg / L praseodymium nitrate, 6 mg / L tripotassium phosphate, 0.4 mg / L rose bengal, 3 mg / L potassium hydroxide, and solvent water.

[0013] Further, the components include 1200 mg / L of zinc dihydrogen phosphate or zinc gluconate, 2 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 2 mg / L of methylbenzotriazole, 0.4 mg / L of praseodymium nitrate, 5 mg / L of tripotassium phosphate, 0.6 mg / L of rose bengal, 4 mg / L of potassium hydroxide, and solvent water.

[0014] The present invention provides a degreasing agent for a closed ethylene glycol process circulating water system, which has the following beneficial effects:

[0015] There is no need to set up an additional treatment process system. The closed ethylene glycol circulating water process system is directly used for circulating reaction to break the emulsified oil and stratify it, and then the oil is removed manually at the system water tank. The treatment process does not require water replacement, and will not cause ethylene glycol loss. The remaining components of the deoiling agent after the reaction are completed can coexist with ethylene glycol for a long time without reacting to modify it. Not only does it solve the oil removal problem, but it also uses the corrosion inhibition performance of this agent to protect the closed ethylene glycol water system from corrosion. It achieves multiple goals at one stroke, with low cost and high cost performance. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with specific examples to help understand the content of the present invention. The methods used in the present invention are all conventional methods unless otherwise specified; the raw materials and devices used are all conventional commercially available products unless otherwise specified.

[0017] It should be noted that the solvent of the present invention may be water, or water and ethylene glycol aqueous solution, and the embodiments of the present invention take water as the solvent. Example 1

[0018] Zinc dihydrogen phosphate or zinc gluconate 800mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 1mg / L, methylbenzotriazole 1mg / L, praseodymium nitrate 0.1mg / L, tripotassium phosphate 5mg / L, rose bengal 0.1mg / L, potassium hydroxide 1mg / L, the solvent is water. Example 2

[0019] Zinc dihydrogen phosphate or zinc gluconate 1500mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 5mg / L, methylbenzotriazole 5mg / L, praseodymium nitrate 1mg / L, tripotassium phosphate 10mg / L, rose bengal 1mg / L, potassium hydroxide 5mg / L, the solvent is water. Example 3

[0020] Zinc dihydrogen phosphate or zinc gluconate 1000mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 2mg / L, methylbenzotriazole 2mg / L, praseodymium nitrate 0.5mg / L, tripotassium phosphate 8mg / L, rose bengal 0.5mg / L, potassium hydroxide 3mg / L, the solvent is water. Example 4

[0021] Zinc dihydrogen phosphate or zinc gluconate 800mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 5mg / L, methylbenzotriazole 5mg / L, praseodymium nitrate 1mg / L, tripotassium phosphate 10mg / L, rose bengal 1mg / L, potassium hydroxide 5mg / L, the solvent is water. Example 5

[0022] Zinc dihydrogen phosphate or zinc gluconate 1000mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 1mg / L, methylbenzotriazole 5mg / L, praseodymium nitrate 1mg / L, tripotassium phosphate 10mg / L, rose bengal 1mg / L, potassium hydroxide 5mg / L, the solvent is water. Example 6

[0023] Zinc dihydrogen phosphate or zinc gluconate 1500mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 2mg / L, methylbenzotriazole 3mg / L, praseodymium nitrate 0.3mg / L, tripotassium phosphate 7mg / L, rose bengal 0.3mg / L, potassium hydroxide 3mg / L, the solvent is water. Example 7

[0024] Zinc dihydrogen phosphate or zinc gluconate 900mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 4mg / L, methylbenzotriazole 4mg / L, praseodymium nitrate 0.3mg / L, tripotassium phosphate 6mg / L, rose bengal 0.4mg / L, potassium hydroxide 3mg / L, the solvent is water. Example 8

[0025] Zinc dihydrogen phosphate or zinc gluconate 1200mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 2mg / L, methylbenzotriazole 2mg / L, praseodymium nitrate 0.4mg / L, tripotassium phosphate 5mg / L, rose bengal 0.6mg / L, potassium hydroxide 4mg / L, the solvent is water.

[0026] Comparative Example 9:

[0027] Zinc dihydrogen phosphate or zinc gluconate 100 mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 1 mg / L, methylbenzotriazole 5 mg / L, praseodymium nitrate 0.1 mg / L, tripotassium phosphate 5 mg / L, rose bengal 0.1 mg / L, potassium hydroxide 4 mg / L, the solvent is water.

[0028] Comparative Example 10:

[0029] Zinc dihydrogen phosphate or zinc gluconate 200 mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetic acid 2 mg / L, methylbenzotriazole 3 mg / L, praseodymium nitrate 0.8 mg / L, tripotassium phosphate 5 mg / L, rose bengal 0.5 mg / L, potassium hydroxide 3 mg / L, the solvent is water.

[0030] 1. Oil removal effect test

[0031] Test water quality: Take water from the circulating cooling water system of the ethylene glycol process of a pharmaceutical company.

[0032] Analysis data: Oil content 140mg / L, emulsification with no obvious stratification.

[0033] Before the addition of degreasing agent, the oil in the water sample was emulsified, and the stratification of the heat transfer oil and the ethylene glycol aqueous solution was not obvious. The degreasing agent formulas of comparative examples 1-8 and comparative examples 9-10 were tested in the laboratory. Take 10 samples respectively, add 1-10 degreasing agents respectively, and stir quickly and evenly. After sufficient reaction for 15 minutes, there is obvious stratification of the heat transfer oil and the ethylene glycol aqueous solution in Example 1-8. Most of the alum flowers gather in the oil layer, and a small part of the alum flowers sink. There is no obvious stratification in comparative examples 9-10. At the same time, after each sample was stored in a low temperature environment (-25°C) for 24 hours, the heat transfer oil and the ethylene glycol aqueous solution still had obvious stratification, and the effect of the agent was not affected by the low temperature environment. Use a separatory funnel to separate the samples of Examples 1-8, and test the corrosion inhibition effect of the lower layer of ethylene glycol-water mixed liquid. The test effect data is shown in Table 1 below:

[0034] Table 1 Water quality test results

[0035]

[0036] 2. Corrosion inhibition effect test

[0037] Use the lower layer of ethylene glycol water mixture to continue the corrosion inhibition effect simulation test. The corrosion inhibition performance test is carried out using the method specified in "Determination of Corrosion Inhibition Performance of Water Treatment Agents - Rotating Hanging Plate Method" GB / T 18175-2000. The test temperature is -25±1℃, the rotation speed is 75-78r / min, and the test time is 72h; it is carried out according to the system operating conditions. According to the system material composition, carbon steel, copper hanging plates and stainless steel hanging plates are selected for rotating hanging plate tests. After testing, the corrosion inhibition rates of the three materials can reach more than 94%, and the test effect data are as shown in Table 2:

[0038] Table 2 Corrosion inhibition test results

[0039]

[0040] 3. Principle of action of the drug

[0041] Zinc dihydrogen phosphate or zinc gluconate mainly plays the role of flocculation and demulsification, magnesium nitrate or magnesium borate or dipotassium magnesium ethylenediaminetetraacetate plays a coordinating role; methylbenzotriazole, praseodymium nitrate, tripotassium phosphate, and potassium hydroxide are used as corrosion inhibitors for ethylene glycol aqueous solution, and synergistically play a corrosion inhibition role with the remaining amount of zinc dihydrogen phosphate or zinc gluconate in the solution; rose red is a colorant.

[0042] Zinc salt is added to water to dissolve Zn 2+ , Zn 2+ It reacts with water to hydrolyze. Zn 2+Hydrolysis produces zinc hydroxide products, and the hydrated molecules are gradually replaced by OH - During substitution and hydrolysis, various hydrated molecules undergo polymerization reactions. Hydrolysis and polymerization reactions occur simultaneously and rapidly, forming various mononuclear and polynuclear coordination compounds. These coordination compounds are all positively charged. Negatively charged emulsified heat transfer oil molecules and suspended particles in water are adsorbed on the surface. After the charge is neutralized, the repulsion between the emulsified heat transfer oil molecules and suspended particles disappears, resulting in condensation and demulsification. The synergistic effect of magnesium salts promotes the speed and morphology of condensation and demulsification. At the same time, zinc salt is also a cathode corrosion inhibitor. Due to the increase in the local pH value in the solution near the cathode area in the metal surface corrosion microbattery, zinc ions and hydroxide ions generate zinc hydroxide and deposit in the cathode area to form a protective film, which inhibits the cathode reaction of the corrosion process and plays a corrosion inhibition role. The remaining amount of zinc salt in the solution after condensation and demulsification synergizes with tolutriazole, praseodymium nitrate, tripotassium phosphate, and potassium hydroxide to act as a corrosion inhibitor. The anions of tolutriazole form an insoluble and extremely stable complex with metal ions and adsorb on the metal surface to form a protective film, thereby playing a corrosion inhibition role. Tripotassium phosphate forms an iron phosphate protective film with carbon steel, achieving a corrosion inhibition effect on the metal surface.

[0043] IV. Application Examples

[0044] Application 1: In September 2022, a pharmaceutical company in Shanghai had a closed ethylene glycol (-25°C) process circulating water system. The water system was a 50% ethylene glycol aqueous solution with a water capacity of 120 tons. Carbon steel, copper, and stainless steel hangers were installed on the bypass hanger. The degreasing agent was formulated in Example 2 and was poured on the system water tank. After the degreasing agent circulated and mixed evenly in the system, the pump was stopped. All the system water fell back into the water tank and stood for 12 hours. The oil and water were separated and the oil layer was separated from the system by manual dredging at the water tank. After the system was running normally, three kinds of hangers of different materials were installed on the bypass hanger for corrosion rate detection. The oil content of the treatment effect was 103 mg / L before degreasing and 3.1 mg / L after degreasing. The corrosion rate of carbon steel was 0.0472 mm / a, the corrosion rate of copper was 0.0021 mm / a, and the corrosion rate of stainless steel was 0.0015 mm / a. So far, the system has been running stably, the performance of ethylene glycol has not been damaged, and the freezing point of the system is under stable control. Treatment cost estimation comparison: Replacing new ethylene glycol costs at least 600,000 yuan, and using this degreasing agent for treatment costs about 60,000 yuan for chemicals and labor.

[0045] Application 2: In April 2023, a pharmaceutical company in Taizhou had a closed ethylene glycol (-7°C) process circulating water system. The water system was a 20% ethylene glycol aqueous solution with a water capacity of 138 tons. Carbon steel, copper, and stainless steel hangers were installed on the bypass hanger. The degreaser was formulated in Example 2 and was poured on the system water tank. After the degreaser circulated and mixed evenly in the system, the pump was stopped. All the system water fell back into the water tank and stood for 12 hours. The oil and water were separated and the oil layer was separated from the system by manual dredging at the water tank. After the system was running normally, three kinds of hangers were installed on the bypass hanger for corrosion rate detection. The oil content of the treatment effect was 55 mg / L before degreasing and 1.4 mg / L after degreasing. The corrosion rate of carbon steel was 0.0521 mm / a, the corrosion rate of copper was 0.0034 mm / a, and the corrosion rate of stainless steel was 0.0029 mm / a. So far, the system has been running stably, the performance of ethylene glycol has not been damaged, and the freezing point of the system is under stable control. Treatment cost estimation comparison: Replacing new ethylene glycol costs at least 280,000 yuan, and using this degreasing agent for treatment costs about 40,000 yuan for chemicals and labor.

[0046] However, what is described above is only a specific embodiment of the present invention and should not be used to limit the scope of implementation of the present invention. Therefore, the replacement of equivalent components, or equivalent changes and modifications made according to the scope of protection of the present invention should still fall within the scope covered by the claims of the present invention.

Claims

1. A degreasing agent for a closed ethylene glycol process circulating water system, characterized in that: The invention comprises the following components: zinc dihydrogen phosphate or zinc gluconate 800-1500 mg / L, magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid 1-5 mg / L, methylbenzotriazole 1-5 mg / L, praseodymium nitrate 0.1-1 mg / L, tripotassium phosphate 5-10 mg / L, potassium hydroxide 1-5 mg / L and rose bengal 0-1 mg / L.

2. The degreasing agent for a closed ethylene glycol process circulating water system according to claim 1, characterized in that: The components include 800 mg / L zinc dihydrogen phosphate or zinc gluconate, 1 mg / L magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 1 mg / L tolyltriazole, 0.1 mg / L praseodymium nitrate, 5 mg / L tripotassium phosphate, 0.1 mg / L rose bengal, 1 mg / L potassium hydroxide, and solvent water.

3. The degreasing agent for a closed ethylene glycol process circulating water system according to claim 1, characterized in that: The components include 1500 mg / L of zinc dihydrogen phosphate or zinc gluconate, 5 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 5 mg / L of methylbenzotriazole, 1 mg / L of praseodymium nitrate, 10 mg / L of tripotassium phosphate, 1 mg / L of rose bengal, 5 mg / L of potassium hydroxide, and solvent water.

4. The degreasing agent for a closed ethylene glycol process circulating water system according to claim 1, characterized in that: The components include 1000 mg / L of zinc dihydrogen phosphate or zinc gluconate, 2 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 2 mg / L of methylbenzotriazole, 0.5 mg / L of praseodymium nitrate, 8 mg / L of tripotassium phosphate, 0.5 mg / L of rose bengal, 3 mg / L of potassium hydroxide, and solvent water.

5. The degreasing agent for a closed ethylene glycol process circulating water system according to claim 1, characterized in that: The components include 800 mg / L zinc dihydrogen phosphate or zinc gluconate, 5 mg / L magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 5 mg / L tolyltriazole, 1 mg / L praseodymium nitrate, 10 mg / L tripotassium phosphate, 1 mg / L rose bengal, 5 mg / L potassium hydroxide, and solvent water.

6. The degreasing agent for a closed ethylene glycol process circulating water system according to claim 1, characterized in that: The components include 1000 mg / L of zinc dihydrogen phosphate or zinc gluconate, 1 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 5 mg / L of methylbenzotriazole, 1 mg / L of praseodymium nitrate, 10 mg / L of tripotassium phosphate, 1 mg / L of rose bengal, 5 mg / L of potassium hydroxide, and solvent water.

7. The degreasing agent for a closed ethylene glycol process circulating water system according to claim 1, characterized in that: The components include 1500 mg / L of zinc dihydrogen phosphate or zinc gluconate, 2 mg / L of magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 3 mg / L of methylbenzotriazole, 0.3 mg / L of praseodymium nitrate, 7 mg / L of tripotassium phosphate, 0.3 mg / L of rose bengal, 3 mg / L of potassium hydroxide, and solvent water.

8. The degreasing agent for a closed ethylene glycol process circulating water system according to claim 1, characterized in that: The components include 900 mg / L zinc dihydrogen phosphate or zinc gluconate, 4 mg / L magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 4 mg / L tolyltriazole, 0.3 mg / L praseodymium nitrate, 6 mg / L tripotassium phosphate, 0.4 mg / L rose bengal, 3 mg / L potassium hydroxide, and solvent water.

9. The degreasing agent for a closed ethylene glycol process circulating water system according to claim 1, characterized in that: The components include 1200 mg / L zinc dihydrogen phosphate or zinc gluconate, 2 mg / L magnesium nitrate or magnesium borate or dipotassium magnesium salt of ethylenediaminetetraacetic acid, 2 mg / L tolyltriazole, 0.4 mg / L praseodymium nitrate, 5 mg / L tripotassium phosphate, 0.6 mg / L rose bengal, 4 mg / L potassium hydroxide, and solvent water.

Images