JP7665399B2 - Chiller water composition and method for operating a chiller - Google Patents

Description

The present invention relates to a chiller water composition for use in a chiller and a method for operating a chiller using the chiller water composition.

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 used for cooling purposes, the circulating chiller water is sometimes called circulating water, circulating cooling water, or cooling water.

Cooling water, hot and cold water, and chiller water are used widely in various facilities and factories 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 a major issue facing cooling water systems, hot and cold water systems, and chiller water systems.

In general, hardness components such as calcium are present in the water used for open cooling towers, 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. Water that contains a large amount of hardness components generally does not corrode metals easily, so corrosion can be suppressed by concentrating the cooling water appropriately and increasing the concentration of hardness components. In such systems, 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 can clog pipes or interfere with heat transfer in heat exchangers.

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, a 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 in which an oxide film is formed using a chemical such as molybdate is often used.

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 mg _CaCO3 /liter or less), making them highly corrosive to iron-based 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).

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

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 in which a pH adjuster is used to create an environment that is less susceptible to corrosion.

However, corrosion can still occur in closed cooling water, cold water for air conditioning, hot water, etc., even in environments where appropriate corrosion inhibitors are used.

JP 2001-137892 A

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 exerted easily and corrosion may occur. Oxidation-type metal corrosion inhibitors such as molybdic acid and nitrous acid passivate iron-based materials by making the surface potential 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 target 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, and that microbial contamination will occur if the storage environment is poor, so improvements in operation were required.

The object of the present invention is to provide a chiller water composition that can provide chiller water with a stable concentration of 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.

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

In the chiller water composition, it is preferable that the TOC of the chiller water composition is 10,000 mg/L or less.

Preferably, the chiller water composition further comprises a fungus inhibitor .

In the chiller water composition, it is preferable that the content of the metal corrosion inhibitor in the chiller water composition is in the range of 0.001 to 1.0% by weight.

In the chiller water composition, it is preferable that the chloride ion and sulfate ion content in the chiller water composition is less than 1 ppm each.

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

In the chiller operation method, it is preferable that the amount of water held by the chiller is 100 L or less.

The present invention provides a chiller water composition that can produce chiller water with a stable concentration of 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.

FIG. 1 is a schematic diagram showing an experimental apparatus in which a new test piece and a corroded test piece are placed facing each other.

The following describes an embodiment of the present invention. This embodiment is an example of implementing the present invention, and the present invention is not limited to this embodiment.

The chiller water composition according to this embodiment contains water and a metal corrosion inhibitor, and has a water content of 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.

After extensive research, the inventors have discovered 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 with a metal contact surface, it is possible to obtain chiller water with a stable concentration of metal corrosion inhibitor even in a sealed chiller water system with a small amount of water.

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

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 counterions 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 structure in a sealed environment with a metal contact surface, 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 originating from chloride ions or sulfate ions is mitigated. As a result, a stable corrosion inhibition treatment effect can be obtained. Considering the accuracy of the analytical method, "substantially free of chloride ions and sulfate ions" preferably means less than 1 ppm.

The chiller water composition according to this embodiment is a container of a specific size made of resin or 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 specific amount can be supplied at any time. The chiller water composition according to this embodiment is packaged so that it can be added to the circulation system of the chiller without dilution, and is supplied to a target component in a sealed environment with a metal contact surface.

The chiller water composition according to this embodiment is mainly applied to a closed chiller water system. The chiller is not limited to certain applications, and may be applied to, for example, various industrial machines, medical machines, scientific instruments, food machinery, etc. The chiller may include, for example, a cooling section, 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.

The water used may be tap water, pure water, ultrapure water, etc., 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. In a chiller water composition using this water, the chloride ion and sulfate ion contents are preferably each less than 1 ppm, more preferably less than 20 ppm chloride ion and less than 1 ppm sulfate ion, and even more preferably the total chloride ion and sulfate ion content is less than 1 ppm.

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 NO ₂ 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.

The chiller water composition according to this embodiment may contain an azole compound, which is a copper-based metal corrosion inhibitor, as a metal corrosion inhibitor to suppress the occurrence of corrosion of copper, copper alloys, etc. Examples of azole compounds that are copper-based corrosion inhibitors include benzotriazole, tolyltriazole, aminotriazole, etc., and the azole compounds may be used alone or in combination of two or more.

The chiller water composition according to this embodiment may contain a fungus inhibitor (also called a bactericide) 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 types.

The chiller water composition according to this embodiment may contain a scale inhibitor to inhibit the formation of scale. Polycarboxylic acid compounds, chelating agents, etc. are used as scale inhibitors. Specific examples of polycarboxylic acid compounds include polyacrylic acid, polymaleic acid, copolymers 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.

In a sealed 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, which may cause a problem of secondary promotion of copper-based metals. Therefore, it is desirable to add a pH adjuster to 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 preferred because they are less likely to become scale components or TOC sources. The pH adjuster may be used alone or in combination of two or more of these.

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

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, and if it exceeds 1.0% by weight, the metal corrosion inhibitor may not function properly and corrosion may progress.

When molybdic acid is used as a metal corrosion inhibitor, the amount is preferably 1.0% by weight (as Mo) or less based on the total weight of the chiller water composition, more preferably in the range of 0.001 to 1.0% by weight, and even more preferably in the range of 0.001 to 0.1% by weight. If the amount of molybdic acid is less than 0.001% by weight, the corrosion inhibition effect for 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 progress instead.

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 inhibition effect for 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 progress instead.

When an azole compound is used as a metal corrosion inhibitor, the amount of the compound is, for example, 1.0% by weight or less, preferably in the range of 0.001 to 1.0% by weight, and more preferably in the range of 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.

When a fungus inhibitor is added to the chiller water composition, the amount of the fungus inhibitor added is, for example, 1.0% by weight or less, 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, based on the total weight of the chiller water composition.

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, and 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 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 NO ₂ .

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 TOC of 10,000 mg/L or less, taking into consideration the increase in TOC caused by blending an appropriate amount of an azole compound, an organic fungus inhibitor, etc. The TOC is preferably 3,000 mg/L or less. It is preferable that the chiller water composition according to this embodiment is one in which the TOC components are composed only of an azole compound and an organic fungus inhibitor.

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 the main components ethylene glycol or propylene glycol, and the water content 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 of this embodiment, which is composed of 99% by weight or more of water.

The chiller water composition according to this embodiment may be used as chiller water as it is, rather than being used by adding concentrated chemicals to the water system as in the case of ordinary cooling water compositions.

<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.

When the fluid temperature that the chiller receives 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, the above-mentioned chiller water composition can be suitably applied as the circulating water of the chiller. By using the above-mentioned chiller water composition, a stable corrosion inhibition treatment effect can be obtained even if the fluid temperature that the chiller receives from the object to be temperature-adjusted is in the range of 5°C or more and less than 50°C.

When the chiller is operated intermittently, for example, at an operating rate of 90% or less, preferably at an operating rate of 10% or more and 90% or less, the above-mentioned chiller water composition can be suitably applied as the circulating water for the chiller. By using the above-mentioned chiller water composition, a stable corrosion inhibition treatment effect can be obtained even when the chiller is operated intermittently.

Note that "operation 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, i.e., the operation time over a seven-day period is intermittent operation with an operation rate of 90% or less.

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.

<Examples 6 and 7, Reference Examples 1 to 5, 8 to 15>
In the Examples and Reference Examples , a rotary corrosion test was carried out by placing a total of four pieces of test pieces, namely, 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, in the following test solution that had been prepared in advance.

The corroded mild steel test pieces were prepared by immersing new mild steel test pieces in Sagamihara City water and corroding them at 35°C with a stirrer stirring at 200 rpm for 7 days.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 at 35°C with a stirrer stirring at 200 rpm for 7 days.

A new mild steel test piece and a corroded mild steel test piece were placed face to face, and a new copper test piece and a corroded copper test piece were placed face to face. 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 attachment resin that can simultaneously attach four test pieces, and a rotary corrosion test was performed. Figure 1 shows a schematic diagram of the experimental device in which the new test piece and the corroded test piece were placed face to face. In the experimental device in Figure 1, the new test piece 12 and the corroded test piece 14 are immersed in the test liquid 16 in the beaker 10 so that they face each other, using the test piece attachment resin 18.

In the rotary corrosion test, the stirring blade (resin for mounting the test specimen) on which the test specimen was installed was rotated at 150 rpm for three days, then the stirring was stopped for two days and the test specimen was left stationary with a zero flow rate, after which the stirring blade on which the test specimen was installed 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) from the difference in the test specimen weight measured before the start of the test.

[Test conditions]
Test liquid: In Examples 6 and 7, Reference Examples 1 to 5, 8, 9 , 14, and 15, the corrosion inhibitor components (benzotriazole and sodium molybdate or sodium nitrite) and fungus inhibitor ( Reference Example 4 and Example 7 only) shown in Table 1 were mixed in a predetermined concentration in pure water, and 500 mg/L of sodium bicarbonate was added as a pH adjuster to adjust the test pH to 7.2±0.2, and 1 L of the mixture was tested in a 1 L beaker. The fungus inhibitor used in Reference Example 4 and Example 7 was a mixture of 2-bromo-2-nitro-1,3-propanediol at 100 mg/L and Caisson WT (trade name of an isothiazolone fungus inhibitor) at 200 mg/L. In Reference 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, and in Reference 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 predetermined concentrations, 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 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 x 30 x 50 mm, #400)
Test period: 7 days (3 days of continuous operation, 2 days of shutdown, 2 days of continuous operation (assuming 2 days of shutdown in a week))

When adding corrosive ions as artificially adjusted water, a diluted solution of sodium chloride was used for chloride ions, and a diluted solution of sodium sulfate was used for sulfate ions. A diluted solution of hydrochloric acid and a diluted solution of sodium hydroxide were used to adjust the pH.

The test results are shown in Tables 1 and 2. In Tables 1 and 2, "Mo" is sodium molybdate (concentration as Mo), " _NO2 " is sodium nitrite (concentration as _NO2 ), "AZ" is benzotriazole, and "MDD" is a unit of corrosion rate, expressed in mg/ ^dm2 ·day.

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 using an ion chromatograph (DIONEX, Integration) by ion chromatography, revealing chloride ions at 18 mg/L and sulfate ions at less than 1 mg/L.

The HACH "DR-3900" was used to measure the molybdenum concentration. The DIONEX "Integrion" ion chromatography was used to measure the nitrite concentration. The HACH "DR-3900" was used to measure the azole compound concentration.

After the test, the number of general bacteria in the water in the beaker was measured. A Sanai Biochecker TTC manufactured by Sanai 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 a logarithmic number of 10.

[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 inhibitor (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.

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

As described above, the chiller water composition of the embodiment provided chiller water with a stable concentration of metal corrosion inhibitor, even in a closed chiller water system with a small amount of water.

10 Beaker, 12 New test piece, 14 Corroded test piece, 16 Test liquid, 18 Resin for mounting test piece.

Claims (7)

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. The chiller water composition of claim 1,
The chiller water composition has a TOC of 10,000 mg/L or less. 3. The chiller water composition of claim 1 or 2,
The chiller water composition further comprises a fungus inhibitor . 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 %. 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. 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. 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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