Circulating water cooling equipment

Abstract

To provide a circulating water cooling facility that can prevent scale formation and corrosion in cooling water piping and discharge cooling water without treatment. [Solution] A circulating water cooling system having a water purification device (3) that reduces the total hardness of the cooling water supplied to the circulating water cooling system (11) to 1.0 mg / L or less, and a solid rust inhibitor (2) that is present in the cooling water circulating through the circulating water cooling system and that releases metal ions into the cooling water that have a higher ionization tendency than iron ions, wherein the total hardness of the cooling water circulating through the circulating water cooling system is 50 mg / L or more and 70 mg / L or less.

Description

[Technical Field]

[0001] This invention relates to a circulating water cooling system that suppresses the formation of rust and scale. [Background technology]

[0002] In the molding process of resins and the like, the molds of the molding device are operated at high temperatures, and the molds are cooled by circulating cooling water. A cooling tower or chiller is used to cool the cooling water that has become hot after cooling the mold. However, particularly when a cooling tower is used, mineral ions in the cooling water are concentrated and precipitate to form scale, so the cooling water is generally softened with an ion exchange resin or the like before being circulated (see, for example, Non-Patent Document 1).

[0003] However, when cooling water is softened, metal ions such as iron ions are eluted from the pipes in the cooling water circulation path into the cooling water, causing rust to form on the pipes, and this rust circulates with the cooling water, which can lead to blockages in the pipes, etc.

[0004] One solution to this problem is to add a chemical anti-rust agent to the softened cooling water, or to add an appropriate cleaning agent to the circulation path of the cooling water where rust has formed, to wash away the rust (see, for example, Patent Document 1 and Non-Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 11-286019 [Patent Document 2] Japanese Patent Application Publication No. 2018-091608 [Patent Document 3] Japanese Patent Application Publication No. 10-109092 [Patent Document 4] Patent No. 6703660 [Patent Document 5] Japanese Patent Publication No. 2021-030194 [Non-patent literature]

[0006] [Non-Patent Document 1] Tetsuo Fujii, "The Latest Full-Color Illustrated Dictionary of Everything You Need to Know About Rust, Corrosion, and Anticorrosion," Natsume Publishing, 2017, pp. 144-145 [Non-patent document 2] Tetsuo Fujii, "The Latest Full-Color Illustrated Dictionary of Everything You Need to Know About Rust, Corrosion, and Anticorrosion," Natsume Publishing, 2017, pp. 225-229 Summary of the Invention [Problem to be solved by the invention]

[0007] However, this method results in the cooling water and water used for cleaning no longer meeting environmental standards for wastewater after the addition of anti-rust chemicals, making it impossible to discharge the water directly into the environment. Furthermore, treating the cooling water to which anti-rust chemicals and cleaning chemicals have been added is costly and places a burden on the environment. Meanwhile, a method is needed that can easily suppress the formation of scale and rust while discharging the cooling water directly into the environment.

[0008] The purpose of this invention is to provide a cooling system for mold cooling water that suppresses the formation of scale in the cooling water supply piping, prevents the formation of rust in the cooling water supply piping, and allows the cooling water to be discharged directly into the environment after long-term use. [Means for solving the problem]

[0009] The means of the present invention are as follows:

[0010] [1] A circulating water cooling system having a water purification device that reduces the total hardness of the cooling water supplied to the circulating water cooling system to 1.0 mg / L or less, and a solid rust inhibitor that is present in the cooling water circulating through the circulating water cooling system and releases metal ions that have a higher ionization tendency than iron ions into the cooling water, wherein the total hardness of the cooling water circulating through the circulating water cooling system is 50 mg / L or more and 70 mg / L or less.

[0011] [2] The circulating water cooling equipment according to [1], wherein the rust inhibitor is made of a porous resin molded body containing biosoluble ceramic fibers and negatively charged organic fibers.

[0012] [3] The circulating water cooling equipment according to [2], wherein the negatively charged organic fiber is an aramid fiber, and the porosity of the resin molded body is 30 to 80%.

[0013] [4] The circulating water cooling system according to [3], wherein the water purifier is a cartridge-type water purifier. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a cooling system for mold cooling water that prevents the formation of scale in the cooling water supply piping, prevents rust on the cooling water supply piping, and allows the cooling water to be discharged directly into the environment after long-term use. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic flow diagram showing an example of a circulating water cooling system according to the present invention. [Figure 2] FIG. 2 is a schematic flow diagram showing an example of a conventional circulating water cooling facility. [Figure 3] FIG. 3 is a photograph showing an example of the appearance of circulating water according to the present invention. [Figure 4] FIG. 4 is a photograph showing an example of the appearance of circulating water in a conventional example. [Figure 5] FIG. 5 is a graph showing the changes in total hardness and pH of the circulating water according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0017] First, a circulating water cooling system 11 according to the present invention will be described with reference to FIG.

[0018] The circulating water cooling system 11 includes at least a rust inhibitor 2, and also uses a water purification system 3. Cooling water circulates between the system and a group of cooled devices 13. Specifically, cooling water cooled in a cooler 12 in the circulating water cooling system 11 is sent by a water pump 1 to a group of cooled devices 13, which consists of multiple cooled devices. After use, the cooling water is heated and returns to the cooler 12. An open-type cooling tower, a closed-type cooling tower, or the like can be used as the cooler 12. The cooling water passes through steel piping.

[0019] The cooler 12 has a water tank 12a for cooling water, and a solid rust inhibitor 2 is placed in the water tank 12a, and the rust inhibitor 2 is settled in the cooling water in the water tank 12a.

[0020] The rust inhibitor 2 is preferably a porous resin molded body containing biosoluble ceramic fibers and negatively charged organic fibers, and more preferably the negatively charged organic fibers are aramid fibers and the resin molded body has a porosity of 30 to 80%. Specifically, "Savillene" (product name) manufactured by Environmental Function Equipment Co., Ltd. is preferred, but not limited to this. The molded body may have any shape, but for example, a disk-shaped molded body with a hole in the center can be used by inserting a number of spacers corresponding to the amount of water required and passing it through a pipe.

[0021] By using the above-mentioned rust inhibitor 2, the total hardness in the cooling water can be maintained at an appropriate value, and the quality of the cooling water can be made to meet the cooling water quality standards. If cooling water that does not meet the cooling water quality standards is used, problems such as the formation of red rust and scale can occur. Furthermore, by using the above-mentioned rust inhibitor 2, no chemicals are added to the cooling water, so it is not impossible to discharge the cooling water directly into the environment.

[0022] The cooling water added to the cooler 12, that is, the cooling water supplied to the circulating water cooling system, is purified water whose total hardness has been reduced to 1.0 mg / L or less by the water purifier 3.

[0023] The water purifier is preferably a water purifier, and more preferably a cartridge-type water purifier. Specifically, the "Cartridge Water Purifier G Series" (product name) manufactured by Organo Corporation is preferred, but is not limited to this. However, it is not preferred to use a water softener, which reduces the total hardness of the cooling water to some extent but cannot convert the cooling water into pure water, instead of a water purifier.

[0024] The water whose total hardness has been reduced by the water purifier 3 becomes pure water after passing through the water purifier 3, and has a total hardness of 1.0 mg / L or less. The pure water supplied to the circulating water cooling system 11 has its total hardness increased by the rust inhibitor 2 in the water tank 12a and maintained at a constant total hardness. The cooling water whose total hardness has been adjusted in this way and circulates between the circulating water cooling system 11 and the group of cooled devices 13 preferably has a total hardness of 50 mg / L or more and 70 mg / L or less, and more preferably 55 mg / L or more and 70 mg / L or less.

[0025] Reducing the total hardness of the cooling water as described above can prevent the formation of scale in circulating water cooling equipment. When using a water softener instead of a pure water purifier, as in the conventional example shown in Figure 2, scale formation may not be sufficiently prevented. This is because conventional water softeners often use calcium-based ion exchange resins, which capture calcium and exchange it for sodium during use, and this sodium can crystallize. Furthermore, in some cases, excessive sodium is used to reabsorb sodium for resin regeneration, and this component can be released into the cooling water.

[0026] At least a part of the group of cooled devices 13 includes high heat load devices 4, one example of which is a mold for a resin molding machine. [Example]

[0027] At a resin product manufacturing plant, pure water prepared using a "Cartridge Water Purifier G Series" (product name) manufactured by Organo Corporation was used as cooling water for a resin molding machine. Furthermore, "Savillene" (product name) manufactured by Environmental Function Equipment Co., Ltd. was added to the cooling water as a rust inhibitor in an amount corresponding to the amount of cooling water. The changes over time in the items listed in Table 2 for the cooling water were measured for two years. The appearance was confirmed by direct visual inspection for the presence or absence of red rust and scale. Measurement of the water quality of the cooling water circulating between the circulating water cooling system 11 and the cooled equipment group 13 was outsourced to Organo Corporation, and the measurements were performed in accordance with JIS K0101, JIS K0102, and JIS B8224.

[0028] Furthermore, at the end of the two-year measurement of the change in cooling water quality over time, the cooling water was judged as to whether it could be discharged or not in accordance with the regulations and measurement methods stipulated in the Water Pollution Control Act and related laws and regulations.

[0029] Measurements were carried out in the same manner as in Example 1, except that the water purification device and the rust inhibitor were changed as shown in Table 1.

[0030] [Table 1]

[0031] [Table 2]

[0032] The appearance of the cooling water and water tank after the experiments in Example 1 and Comparative Example 1 are shown in Figures 3 and 4. As shown in Figures 3 and 4, in Example 1, the cooling water was colorless and transparent compared to Comparative Example 1, indicating that red rust was suppressed. It is also clear that no scale formed in the water tank in either Example 1 or Comparative Example 1. On the other hand, scale was observed in Comparative Examples 2 and 3, which used a water softener instead of a water purifier.

[0033] Figure 5 shows the changes in total hardness and pH of the cooling water in Example 1. It can be seen that the total hardness of the cooling water rose sharply at the beginning of the experiment and then stabilized at around 70 mg / L. This is because the total hardness of the cooling water, which had been set to 1.0 mg / L or less, rose sharply due to the release of metal ions from the rust inhibitor ("Savillene" (trade name)), and the total hardness was then maintained at around 70 mg / L. Similarly, Figure 5 also shows that the pH of the cooling water stabilized at around 8.0. This is because the rust inhibitor ("Savillene" (trade name)) does not affect the pH of the cooling water.

[0034] As shown in Table 2, in Comparative Example 2, in which chemical rust inhibitors were used, there were more metal ions and the like present in the cooling water after the experiment compared to Example 1, and it can be seen that the water quality had deteriorated. [Explanation of symbols]

[0035] 1. Water pump 2. Rust inhibitor 3 Water purification equipment 4 High heat load equipment 11 Circulating water cooling equipment 12 Cooler 12a Aquarium 13 Cooled equipment group

Claims

1. A circulating water cooling system having a water purification device that reduces the total hardness of the cooling water supplied to the circulating water cooling system to 1.0 mg / L or less, and a solid rust inhibitor that is present in the cooling water circulating through the circulating water cooling system and releases metal ions that have a higher ionization tendency than iron ions into the cooling water, wherein the total hardness of the cooling water circulating through the circulating water cooling system is 50 mg / L or more and 70 mg / L or less.

2. 2. The circulating water cooling system according to claim 1, wherein the anticorrosive agent is a porous resin molded body containing biosoluble ceramic fibers and negatively charged organic fibers.

3. 3. The circulating water cooling system according to claim 2, wherein the negatively charged organic fiber is an aramid fiber, and the porosity of the resin molding is 30 to 80%.

4. 4. The circulating water cooling system according to claim 3, wherein the water purifier is a cartridge-type water purifier.

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