Chiller water composition and method for operating a chiller

Abstract

To provide a chiller water composition that can give chiller water with a stable concentration of a metal corrosion inhibitor even in a closed chiller water system with a small water-holding capacity; and a method for operating a chiller using the chiller water composition.SOLUTION: A chiller water composition contains water and a metal corrosion inhibitor, with the water content of 90 wt.% or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a chiller water composition for use in a chiller and a method of operating a chiller using the chiller water composition. [Background technology]

[0002] A chiller system (cooling water circulation system), sometimes simply called a chiller, is a device that circulates water or a low-temperature heat medium adjusted to a specified temperature to cool, heat, or regulate the temperature of a target object such as a sample or device. Since most chillers are intended for cooling purposes, the circulating chiller water is sometimes called circulating water, circulating cooling water, or cooling water.

[0003] In various facilities and factories, cooling water, hot and cold water, and chiller water are widely used for cooling and heating equipment. In such water systems, the pipes and heat exchangers are often made of metals such as iron. How to prevent corrosion of such metal pipes and heat exchangers is one of the major issues facing cooling water systems, hot and cold water systems, and chiller water systems.

[0004] In general, hardness components such as calcium are present in the open-type cooling water that uses a cooling tower, and when part of the water evaporates in the cooling tower for cooling, the hardness components in the water become concentrated unless part of the cooling water is forcibly replaced. Since water that contains a large amount of hardness components generally does not corrode metals easily, corrosion can be suppressed by appropriately concentrating the cooling water and increasing the concentration of the hardness components. In such a system, it is possible to suppress damage to the cooling water system by adding a scale inhibitor such as a water-soluble polymer dispersant to suppress the formation of scale that clogs piping and interferes with heat transfer in heat exchangers.

[0005] Furthermore, when highly corrosive water, such as recovered water from process cleaning water in semiconductor factories, is used as make-up water for a cooling water system, the water generally has a low concentration of hardness components, and even if concentrated, the circulating cooling water has low hardness (for example, total hardness of 200 mgCaCO3 / L or less), making it highly corrosive to ferrous metals. When such water is used as cooling water, the methods for inhibiting corrosion of ferrous metals are limited, and a passive corrosion inhibition method that forms an oxide film using chemicals such as molybdate is often used.

[0006] On the other hand, closed water systems such as closed cooling water, cold water for air conditioning, hot water, chiller water, etc. do not have cooling towers, the water is rarely concentrated, and generally has low hardness (for example, total hardness of 200 mgCaCO3 / liter or less), making it highly corrosive to ferrous metals. In addition, water and chemical replacement is extremely infrequent. Furthermore, operating conditions are often intermittent, and a specified flow rate cannot be constantly ensured. For these reasons, passive corrosion inhibition methods using chemicals such as molybdates and nitrites are often adopted (see Patent Document 1).

[0007] Based on these technical theories, different chemicals are used depending on whether the water system is open or closed, or depending on the make-up water used, etc.

[0008] In addition, in closed water systems, copper-based and aluminum-based materials are often used as constituent materials for pipes, heat exchangers, water tanks, fins, etc. Corrosion inhibitors are often used for copper-based and aluminum-based materials, but because they are prone to corrosion when the pH becomes acidic or alkaline, methods are also used to create an environment that is less susceptible to corrosion by using pH adjusters.

[0009] However, corrosion still occurs in closed system cooling water, cold water for air conditioning, hot water, and the like, even in environments where appropriate corrosion inhibitors are used. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2001-137892 A Summary of the Invention [Problem to be solved by the invention]

[0011] Many closed water systems, especially chiller water systems, have a relatively small amount of water, and even if the concentration of metal corrosion inhibitors to be added to closed water systems is calculated, the actual concentration may not be as calculated. If the concentration is insufficient, the corrosion inhibitor effect is not easily achieved, and corrosion may occur. Oxidation-type metal corrosion inhibitors such as molybdic acid and nitrous acid are passivated by making the surface potential of iron-based materials more noble, but if the concentration is excessive, it may cause problems depending on the metal type. For example, in white gas pipes and aluminum piping, it may promote the elution of zinc and aluminum. In order to prevent these problems, pure water may be supplied, but installing a pure water device around the object is costly and there is a risk that stable pure water cannot be obtained due to a malfunction of the softening device. It is also possible to store pure water in a specified container in advance, but in that case, there is a risk that the pure water will freeze in winter or in cold areas, or that microbial contamination will occur if the storage environment is poor, so improvements in operation were required.

[0012] An object of the present invention is to provide a chiller water composition that can produce chiller water with a stable concentration of a metal corrosion inhibitor even in a closed chiller water system with a small amount of water held, and a method for operating a chiller that uses the chiller water composition. [Means for solving the problem]

[0013] The present invention is , azole compounds and molybdic acid Metal corrosion inhibitors and 、 Including A chiller water composition comprising: The water content is 90% by weight or more. The chiller water composition has a chloride ion content of less than 18 ppm, and the weight ratio of the azole compound in the chiller water composition is 2.5 or more and in the range of 0.1 to 0.2% by weight relative to the weight ratio of the molybdic acid (as Mo), and the azole compound is at least one of benzotriazole, tolyltriazole, and aminotriazole. It is a chiller water composition.

[0014] In the chiller water composition, the TOC of the chiller water composition is preferably 10,000 mg / L or less.

[0015] Chiller water composition Things , Plus fungal inhibitors It is preferred that the compound contains

[0016] In the chiller water composition, the content of the metal corrosion inhibitor in the chiller water composition is preferably in the range of 0.001 to 1.0% by weight.

[0017] In the chiller water composition, it is preferable that the content of chloride ions and sulfate ions in the chiller water composition is each less than 1 ppm.

[0019] The present invention is a method for operating a chiller using the chiller water composition, in which the chiller water composition is used as it is as chiller water.

[0020] In the chiller operation method, the amount of water held in the chiller is preferably 100 L or less. Effect of the Invention

[0021] The present invention makes it possible to provide a chiller water composition that can produce chiller water with a stable concentration of a metal corrosion inhibitor even in a closed chiller water system that holds a small amount of water, and a method for operating a chiller that uses the chiller water composition. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram showing an experimental setup in which a new test piece and a corroded test piece were placed face-to-face. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the present invention. The embodiment is merely an example of implementing the present invention, and the present invention is not limited to the embodiment.

[0024] The chiller water composition according to the present embodiment is a composition containing water and a metal corrosion inhibitor, and the water content is 90% by weight or more. It is preferable that the chloride ion and sulfate ion contents in the chiller water composition are each less than 1 ppm.

[0025] As a result of extensive research, the inventors have found that by using a composition containing water and a metal corrosion inhibitor, with the water content adjusted to 90% by weight or more, and supplying the composition to a target structure in a sealed environment whose contact surface is metal, it is possible to obtain chiller water with a stable concentration of metal corrosion inhibitor even in a sealed chiller water system that holds a small amount of water.

[0026] By using a composition containing water and a metal corrosion inhibitor with the water content adjusted to 90% by weight or more, and supplying the composition to a target structure in a sealed environment, for example, whose contact surface is metal, it is possible to prevent excessive or insufficient addition of the metal corrosion inhibitor and supply chiller water with a stable concentration of the metal corrosion inhibitor.

[0027] In addition, if a composition containing water and a metal corrosion inhibitor, with the water content adjusted to 90% by weight or more, and the chloride ion and sulfate ion contents adjusted to less than 1 ppm each is used, even if chloride ions or sulfate ions are brought in as counter ions of the metal corrosion inhibitor component or the fungus inhibitor component, the inclusion of one of these ions is acceptable. The inventors have not yet elucidated a clear mechanism by which corrosion risk is improved by using a composition containing water and a metal corrosion inhibitor, with the water content adjusted to 90% by weight or more, and the chloride ion and sulfate ion contents in the chiller water composition adjusted to less than 1 ppm each, and supplying the composition to a target component in a sealed environment whose contact surface is metal, but it is presumed that this is because, if there is almost no supply of chloride ions and sulfate ions, the promotion of corrosion risk due to the combination of corrosion mechanisms initiated by chloride ions or sulfate ions is mitigated. As a result, a stable corrosion inhibition treatment effect can be obtained. "Substantially free of chloride ions and sulfate ions" preferably means less than 1 ppm, taking into account the accuracy of the analytical method.

[0028] The chiller water composition according to this embodiment is a container of a predetermined size made of resin, glass, etc., in which water, a metal corrosion inhibitor, and optionally a bacteria count inhibitor, a scale inhibitor, a pH adjuster, etc. are sealed and packed, so that a predetermined amount can be supplied at any time. The chiller water composition according to this embodiment is packaged so that it can be introduced into the circulation system of a chiller without dilution, and is supplied to a target component in a sealed environment whose contact surface is metal.

[0029] The chiller water composition according to the present embodiment is mainly applied to a closed chiller water system. The chiller is not limited to a specific application, and may be applied to, for example, various industrial machines, medical machines, physicochemical equipment, food machinery, etc. The chiller may include, for example, a cooling unit, and may include a water tank, a pump, etc. The chiller may be an air-cooled chiller or a water-cooled chiller. The amount of water held by the chiller is, for example, 100 L or less.

[0030] Examples of the water used include tap water, pure water, and ultrapure water, but it is preferable to use pure water or ultrapure water. Here, pure water refers to water that has been treated so that the chloride ion and sulfate ion contents are both less than 1 ppm. Ultrapure water is water with an electrical resistivity of 15 MΩ·cm or more. The chiller water composition using this water preferably contains less than 1 ppm of chloride ion and sulfate ion, more preferably less than 20 ppm of chloride ion and less than 1 ppm of sulfate ion, and even more preferably less than 1 ppm of the total content of chloride ion and sulfate ion.

[0031] The chiller water composition according to the present embodiment may contain molybdic acid, nitrous acid, and the like, which are iron-based corrosion inhibitors, as a metal corrosion inhibitor. Molybdic acid is, for example, compounded as a molybdate, and specific examples of the molybdate include molybdates such as orthomolybdate, paramolybdate, and metamolybdate. Specific examples of the salt in this case include sodium salt, potassium salt, and ammonium salt. Among these molybdates, sodium orthomolybdate is particularly preferred. When considering the weight of molybdic acid, it is preferable to convert it to Mo in terms of ease of calculation in terms of composition design. Nitrous acid is, for example, compounded as a nitrite, and specific examples of the nitrite include sodium salt, potassium salt, and ammonium salt. When considering the weight of nitrous acid, it is preferable to convert it to NO2 in terms of composition design in terms of ease of calculation. The iron-based corrosion inhibitor may be used alone or in combination of two or more of these.

[0032] The chiller water composition according to the present embodiment may contain an azole compound, which is a copper-based metal corrosion inhibitor, as a metal corrosion inhibitor to inhibit the occurrence of corrosion of copper, copper alloys, etc. Examples of the azole compound, which is a copper-based corrosion inhibitor, include benzotriazole, tolyltriazole, aminotriazole, etc., and the azole compound may be used alone or in combination of two or more kinds.

[0033] The chiller water composition according to the present embodiment may contain a fungus inhibitor (also called a bactericide) in order to suppress the generation of slime and microbial corrosion. Examples of fungus inhibitors include organic sulfur-nitrogen compounds and organic bromine compounds, and specific examples thereof include 2-methyl-3-isothiazolone, 5-chloro-2-methyl-3-isothiazolone, 4,5-dichloro-2-n-octyl-3-isothiazolone, and 2-bromo-2-nitro-1,3-propanediol. The fungus inhibitor may be used alone or in combination of two or more of these.

[0034] The chiller water composition according to the present embodiment may contain a scale inhibitor to inhibit the generation of scale. As the scale inhibitor, a polycarboxylic acid compound, a chelating agent, or the like is used. Specific examples of the polycarboxylic acid compound include polyacrylic acid, polymaleic acid, a copolymer of acrylic acid and 2-acrylamido-2-methylpropanesulfonic acid, and sodium salts thereof. Specific examples of chelating agents include L-ascorbic acid, erythorbic acid and their sodium salts, ethylenediaminetetraacetic acid (EDTA), ethylenediamine-N,N'-disuccinic acid (EDDS), nitrilotriacetic acid (NTA), diethylenetriaminepentaacetic acid (DTPA), L-aspartic acid diacetic acid (ASDA), L-glutamic acid diacetic acid (GLDA), hydroxyethylethylenediaminetriacetic acid (HEDTA), methylglycine diacetic acid (MGDA), glycol ether diaminetetraacetic acid (GEDTA), triethylenetetraminehexaacetic acid (TTHA), hydroxyethyliminodiacetic acid (HIDA), and their sodium salts, potassium salts, hydrates, etc. The scale inhibitors may be used alone or in combination of two or more.

[0035] In a closed water environment such as chiller water, water is hardly exchanged, so when metal corrosion occurs in the system, the pH may rise due to hydroxide ions generated by the progress of the cathode reaction, and a problem of promoting copper-based metals may occur secondarily. Therefore, it is desirable to blend a pH adjuster into the chiller water composition according to this embodiment. Examples of pH adjusters include sodium carbonate, potassium carbonate, sodium bicarbonate, sodium phosphate, disodium hydrogen phosphate, potassium phosphate, trisodium citrate, sodium gluconate, etc., and carbonates and bicarbonates such as sodium carbonate, potassium carbonate, and sodium bicarbonate are preferable because they are unlikely to become scale components or TOC sources. The pH adjuster may be used alone or in combination of two or more of these.

[0036] The pH of the chiller water composition is preferably at least 4, and more preferably at least 5. The upper limit of the pH of the chiller water composition is, for example, 10 or less.

[0037] The content of the metal corrosion inhibitor in the chiller water composition is in the range of 0.001 to 1.0% by weight, and preferably in the range of 0.005 to 0.5% by weight. If the content of the metal corrosion inhibitor in the chiller water composition is less than 0.001% by weight, the metal corrosion inhibitor effect may not be obtained, whereas if it exceeds 1.0% by weight, the metal corrosion inhibitor may not function properly and corrosion may progress.

[0038] When molybdic acid is used as a metal corrosion inhibitor, the amount of molybdic acid is preferably 1.0% by weight (as Mo) or less, more preferably 0.001 to 1.0% by weight, and even more preferably 0.001 to 0.1% by weight, based on the total weight of the chiller water composition. If the amount of molybdic acid is less than 0.001% by weight, the corrosion inhibitory effect for iron-based metals may not be obtained, and if it exceeds 1.0% by weight, the oxidizing power may become too high depending on the type of metal, and corrosion may progress instead.

[0039] When nitrous acid is added as a metal corrosion inhibitor, the amount of nitrous acid added is, for example, 1.0% by weight or less (as NO2) relative to the total weight of the chiller water composition, preferably in the range of 0.001 to 1.0% by weight, and more preferably in the range of 0.001 to 0.1% by weight. If the amount of nitrous acid added is less than 0.001% by weight, the corrosion inhibitory effect on ferrous metals may not be obtained, and if it exceeds 1.0% by weight, the oxidizing power may become too high depending on the type of metal, and corrosion may instead progress.

[0040] When an azole compound is used as a metal corrosion inhibitor, the amount of the azole compound is, for example, 1.0% by weight or less, preferably 0.001 to 1.0% by weight, and more preferably 0.001 to 0.05% by weight, based on the total weight of the chiller water composition. If the amount of the azole compound is less than 0.001% by weight, the effect of inhibiting corrosion of copper-based metals may not be obtained, and if it exceeds 1.0% by weight, the TOC source increases, which may increase the environmental load and cause microbial contamination.

[0041] When a fungus inhibitor is added to the chiller water composition, the amount added is, for example, 1.0 wt % or less relative to the total weight of the chiller water composition, preferably in the range of 0.001 to 1.0 wt %, and more preferably in the range of 0.001 to 0.1 wt %.

[0042] In the chiller water composition, when an azole compound is included, the azole compound is preferably blended in a weight ratio of at least one of molybdic acid and nitrous acid, which are iron-based corrosion inhibitors (i.e., the weight ratio of the azole compound is 1 or more relative to the total weight ratio of at least one of molybdic acid and nitrous acid), and the weight ratio of the azole compound: at least one of molybdic acid and nitrous acid is preferably in the range of 1:1 to 100:1, more preferably in the range of 1:1 to 10:1. In cases where the proportion of copper-based metals in the composition of the treated metal is low, the weight ratio of the azole compound: at least one of molybdic acid and nitrous acid may be preferably in the range of about 1:10 to 10:1. Here, the weight of molybdic acid is the weight as Mo, and the weight of nitrous acid is the weight as NO2.

[0043] The chiller water composition according to this embodiment is a composition that is not composed of an organic solvent. "Not composed of an organic solvent" is defined as a composition that has a TOC of 10,000 mg / L or less, taking into consideration the increase in TOC caused by blending an azole compound, an organic fungus inhibitor, etc. in an appropriate amount. The TOC is preferably 3,000 mg / L or less. It is preferable that the chiller water composition according to this embodiment is a composition in which the TOC components are composed only of an azole compound and an organic fungus inhibitor.

[0044] The weight percentage of water in the chiller water composition is 90% by weight or more, preferably 99% by weight or more, and more preferably 99.5% by weight or more. In general, antifreeze concentrate contains 70 to 80% by weight of ethylene glycol or propylene glycol as the main component, and the water percentage is about 20 to 30% by weight, and is used as is or diluted several times with water. Therefore, it should be considered as having completely different properties from the chiller water composition according to the present embodiment, which is composed of 99% by weight or more of water.

[0045] The chiller water composition according to the present embodiment may be used as chiller water as it is, without adding a concentrated chemical to a water system as in the case of a typical cooling water composition.

[0046] <How to operate the chiller> The chiller operating method according to the present embodiment is an operating method using the chiller water composition. For example, the chiller may be operated by using the chiller water composition as it is as circulating water (also called circulating cooling water or cooling water) for the chiller.

[0047] The above chiller water composition can be suitably used as circulating water for a chiller when the temperature of the fluid received by the chiller from the object to be temperature adjusted is, for example, in the range of 5° C. or more and less than 50° C., and preferably in the range of 10° C. or more and less than 30° C. By using the above chiller water composition, a stable corrosion inhibition treatment effect can be obtained even if the temperature of the fluid received by the chiller from the object to be temperature adjusted is in the range of 5° C. or more and less than 50° C.

[0048] When the chiller is operated intermittently, for example, at an operating rate of 90% or less, preferably at an operating rate of 10% to 90%, the chiller water composition can be suitably used as circulating water for the chiller. By using the chiller water composition, a stable corrosion inhibition treatment effect can be obtained even when the chiller is operated intermittently.

[0049] Note that an "operational rate of 90% or less" means that the chiller is stopped for one day or more per week, or for three hours or more per day; in other words, the operating time over a seven-day period is intermittent operation with an operating rate of 90% or less. EXAMPLES

[0050] EXAMPLES The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0051] <Example> 6,7, Reference example 1 ~5,8 ~15> Working Example , reference example A rotary corrosion test was carried out in the following test solution prepared in advance, in which a total of four pieces of test pieces (a brand new mild steel test piece, a copper test piece, and a mild steel test piece and a copper test piece that had been corroded separately) were placed together.

[0052] The corroded mild steel test pieces were prepared by immersing new mild steel test pieces in Sagamihara city water and corroding them for 7 days at 35°C with agitation at 200 rpm. The corroded copper test pieces were prepared by immersing new copper test pieces in an ammonia-containing solution prepared by adding 30% ammonia water to pure water to adjust the ammonium ion concentration to 60 ppm, and corroding them for 7 days at 35°C with agitation at 200 rpm.

[0053] A total of four test pieces were immersed in a beaker filled with 1 L of test liquid using a special cross-shaped test piece mounting resin that can simultaneously mount a total of four test pieces, such as a new mild steel test piece facing a corroded mild steel test piece, and a new copper test piece facing a corroded copper test piece, and a rotary corrosion test was performed. Figure 1 shows a schematic diagram of the experimental apparatus in which the new test piece and the corroded test piece are placed facing each other. In the experimental apparatus in Figure 1, a new test piece 12 and a corroded test piece 14 are immersed in the test liquid 16 in a beaker 10 facing each other using a test piece mounting resin 18.

[0054] In the rotary corrosion test, the impeller (resin for mounting the test specimen) with the test specimen attached was rotated at 150 rpm for three days, then the stirring was stopped for two days and the specimen was left stationary with a zero flow rate, after which the impeller with the test specimen attached was rotated again at 150 rpm for two days. After seven days, the test specimen was removed, and the originally brand new test specimen was derusted and weighed. The corrosion rates of mild steel and copper were measured by the mass subtraction method in accordance with the Industrial Water Corrosion Test Method (JIS-K0100) based on the difference from the test specimen weight measured before the start of the test.

[0055] [Test conditions] Test Solution: Example 6,7, Reference example 1~ 5,8, In 9, 14, and 15, the corrosion inhibitor components (benzotriazole and sodium molybdate or sodium nitrite) and fungus inhibitor ( reference Example 4 and Example 7) were mixed at a predetermined concentration, 500 mg / L of sodium bicarbonate was added as a pH adjuster, and the test pH was adjusted to 7.2±0.2. 1 L of the mixture was placed in a 1 L beaker for testing. reference The fungus inhibitors used in Examples 4 and 7 were 2-bromo-2-nitro-1,3-propanediol at a concentration of 100 mg / L and Caisson WT (the trade name of an isothiazolone fungus inhibitor) at a concentration of 200 mg / L. referenceIn Example 13, artificially adjusted water (water prepared by dissolving sodium chloride in pure water when supplying chloride ions, or sodium sulfate in pure water when supplying sulfate ions) was used as the water. reference In Examples 10 to 12, Sagamihara well water (the water quality of Sagamihara well water is shown in Table 3) was used as the water, and the corrosion inhibitor components shown in Table 2 (benzotriazole and sodium molybdate or sodium nitrite) were mixed at the specified concentrations, and 500 mg / L of sodium bicarbonate was added as a pH adjuster to adjust the test pH to 7.2±0.2. 1 L of this was tested in a 1 L beaker. Water temperature: 30℃ Stirring speed: 150 rpm Test piece: Mild steel SS-400 (10 x 30 x 50 mm, #400) Copper C1220P (10×30×50mm, #400) Test period: 7 days (3 days of continuous operation, 2 days of stoppage, 2 days of continuous operation (assuming 2 days of stoppage in a week))

[0056] When adding corrosive ions as artificial adjusted water, diluted solutions of sodium chloride were used for chloride ions and sodium sulfate for sulfate ions. Dilute solutions of hydrochloric acid and sodium hydroxide were used for pH adjustment.

[0057] The test results are shown in Tables 1 and 2. In Tables 1 and 2, "Mo" is sodium molybdate (concentration is Mo), "NO2" is sodium nitrite (concentration is NO2), "AZ" is benzotriazole, and "MDD" is the unit of corrosion rate in mg / dm 2 Represents day.

[0058] Pure water was mixed with 800 mg / L of sodium molybdate, 2,000 mg / L of benzotriazole, 100 mg / L of 2-bromo-2-nitro-1,3-propanediol, 200 mg / L of Caisson WT, and 500 mg / L of sodium bicarbonate (Example 7). Measurements were performed by ion chromatography using an ion chromatograph (DIONEX, Integrion) to find that the chloride ion content was 18 mg / L and the sulfate ion content was less than 1 mg / L.

[0059] The molybdenum concentration was measured using the HACH "DR-3900." The nitrite concentration was measured using the DIONEX "Integrion" ion chromatography. The azole compound concentration was measured using the HACH "DR-3900."

[0060] After the test, the number of general bacteria in the water in the beaker was measured. A San-Ai Biochecker TTC made by San-Ai Oil Co., Ltd. was placed in the water for 5 seconds, removed, and then cultured in a thermostatic chamber set at 30°C for 48 hours. The colony pattern appearing on the surface of the removed Biochecker medium was compared with the sample and calculated as the number of colonies in the logarithmic order of 10.

[0061] [Pass / Fail criteria] In this test, the pass / fail criteria were set as follows: Corrosion rate of mild steel (MDD): 10 or less is considered good. Copper corrosion rate (MDD): 0.5 or less is considered good. Residual concentration of iron-based corrosion inhibitors (molybdic acid (as Mo), nitrous acid (as NO2)): 70% or more is considered good. Residual concentration of copper-based corrosion inhibitor (azole compound): 90% or more is considered good.

[0062] [Table 1]

[0063] [Table 2]

[0064] [Table 3]

[0065] implementation For example The composition provided a stable metal corrosion inhibitor concentration in the chiller water. referenceWhen the composition of Example 8 was implemented in an actual chiller device (water capacity: 50 L) and operated, stable operation was possible for half a year without any problems based on the pass / fail judgment mentioned above.

[0066] As described above, the chiller water composition of the examples made it possible to obtain chiller water with a stable concentration of metal corrosion inhibitor even in a closed chiller water system with a small amount of water. [Explanation of symbols]

[0067] 10 beaker, 12 new test specimen, 14 corroded test specimen, 16 test liquid, 18 resin for mounting test specimen.

Claims

1. 1. A chiller water composition comprising water and a metal corrosion inhibitor comprising an azole compound and molybdic acid, The water content is 90% by weight or more, The content of chloride ions in the chiller water composition is less than 18 ppm; the weight percentage of the azole compound in the chiller water composition is 2.5 or more relative to the weight percentage of the molybdic acid (as Mo) and is in the range of 0.1 to 0.2 wt. %, The chiller water composition, wherein the azole compound is at least one of benzotriazole, tolyltriazole, and aminotriazole.

2. 2. The chiller water composition of claim 1, The chiller water composition has a TOC of 10,000 mg / L or less.

3. 3. The chiller water composition of claim 1 or 2, The chiller water composition further comprises a fungus inhibitor.

4. The chiller water composition according to any one of claims 1 to 3, A chiller water composition, characterized in that the content of the metal corrosion inhibitor in the chiller water composition is in the range of 0.001 to 1.0 wt %.

5. The chiller water composition according to any one of claims 1 to 4, The chiller water composition, wherein the chloride ion and sulfate ion contents in the chiller water composition are each less than 1 ppm.

6. A method for operating a chiller using the chiller water composition according to any one of claims 1 to 5, comprising: A method for operating a chiller, comprising using the chiller water composition as it is as chiller water.

7. A method for operating a chiller according to claim 6, comprising the steps of: A method for operating a chiller, characterized in that the amount of water held in the chiller is 100 L or less.

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