Flushing water treatment system and flushing water treatment method

Abstract

To more securely remove contaminants in flushing water, such as zinc, compared to the prior art.SOLUTION: A system for treating flushing water from a circulation pipeline 5 includes a filtration device 11 which filters flushing water, and an ion exchange resin 12 which is located downstream of the filtration device 11 and increases pH of the flushing water passing through the filtration device 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a flushing water treatment system and a flushing water treatment method. [Background technology]

[0002] For example, carbon steel pipes are often used for the heat source piping of air conditioning equipment, but after construction, the inside of the pipes contains foreign objects such as welding slag and sealing tape generated during construction, shavings from the pipe material, sand and dust that have entered from the outside, etc. In addition, so-called white gas pipes, which are zinc-plated on the inside and outside of the pipe material, also contain zinc. In order to remove these, flushing is performed before actual operation.

[0003] Typical flushing involves replacing the water in the piping system to be flushed, or filling it with water and then using a pump to clean the inside of the pipes. However, the wastewater after flushing contains contaminants such as zinc, as mentioned above, so consideration must be given to the environment. For example, zinc in the wastewater after flushing is strictly regulated by the Sewerage Act, the Water Pollution Prevention Act, and local government ordinances. For this reason, drainage-free flushing, in which the flushing wastewater is not discharged outside after flushing, is attracting attention.

[0004] From this viewpoint, as disclosed in Patent Document 1, flushing water has conventionally been filtered through a filter to remove the contaminants and the like before being discharged. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 7309490 Summary of the Invention [Problem to be solved by the invention]

[0006] However, even if the flushing water is filtered through a filter in this way, the turbidity of the filtered flushing water cannot be reduced. The inventor investigated the cause and found that the pH of the flushing water was the cause.

[0007] In other words, in the method of filtering flushing water using conventional filters, no particular attention was paid to the pH of the flushing water. As a result, for example, dissolved zinc and fine zinc particles could not be captured by the filter, and as a result, turbidity could not be sufficiently reduced. Furthermore, the remaining dissolved zinc and fine zinc particles could cause corrosion in the piping system. In this regard, the inventors have found that if the pH of the flushing water is increased to a certain extent, the dissolved zinc will precipitate and can be collected using a filter or the like.

[0008] The present invention has been made in view of the above points, and aims to solve the above problems by providing a flushing water treatment system and treatment method suitable for treating flushing water. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the present invention provides a system for treating flushing water from a piping system, comprising a filtering means for filtering the flushing water and a pH increasing means for increasing the pH of the flushing water, and characterized in that the filtering means filters the flushing water whose pH has been increased by the pH increasing means.

[0010] According to the present invention, the pH-raising means for raising the pH of the flushing water that has passed through the filtering means can be used to raise the pH of the flushing water after flushing, after foreign matter and impurities in the flushing water have been collected by, for example, a filter in the filtering means. This can precipitate, for example, dissolved zinc in the flushing water, or increase the diameter of zinc particles that exist in the form of fine particles. This allows dissolved zinc and zinc particles that cannot be collected by the filtering material of the filtering means, for example, a filter, to be collected by the filter. Therefore, for example, precipitated zinc particles can be prevented from remaining as fine particles and causing corrosion.

[0011] The pH increasing means preferably increases the pH of the flushing water to 8 to 9. Increasing the pH of the flushing water to such a level makes it possible to more reliably precipitate dissolved zinc and also increases the diameter of zinc fine particles.

[0012] The flushing water before the pH is increased by the pH increasing means may contain zinc, which cannot be filtered out by the filtering means.

[0013] An example of the pH-increasing means is an ion exchange resin. In this case, by using a strongly basic or weakly basic anion exchange resin, it is possible to prevent an increase in salt concentration and simultaneously adjust the pH. When the water passes through the anion exchange resin, chloride ions Cl in the water are released. - Anions such as these are adsorbed onto the anion exchange resin, and hydroxide ions OH - is released into the water. At this time, chloride ions are removed and the pH rises. - It also has the effect of reducing the risk of corrosion of pipes, etc., by adsorbing anions that cause corrosion of pipes, etc.

[0014] The pH-increasing means is preferably located downstream of the filtration means, i.e., if the only purpose is to precipitate dissolved zinc or to increase the diameter of zinc particles present in the form of fine particles, the pH-increasing means may be located either upstream or downstream of the filtration means. However, when an ion exchange resin is used as a pH-increasing means, the liquid whose pH has been increased by the ion exchange resin beyond the target value is mixed with the flushing water to adjust the entire flushing water to the target pH value. Therefore, if a liquid with an excessively high pH, ​​such as immediately after passing through the ion exchange resin, is passed through the filtration means, there is a risk of degrading the material of the filtration means, for example, the filter. Therefore, to prevent this situation, the pH-increasing means can be located downstream of the filtration means, preventing the flushing water, whose pH has been increased by the pH-increasing means, from passing through the filtration means. For example, by locating the pH-increasing means and the filter at a distance equal to the length of the flow path in the piping system, the pH of the flushing water at the inlet side of the filtration means can be diluted and lowered by the amount of time it has flowed through the flow path. Furthermore, by arranging the pH increasing means downstream of the filtering means, the flushing water immediately after being filtered by the filtering means can be passed through the ion exchange resin, thereby preventing clogging of the ion exchange resin. Similarly, when using a chemical such as sodium hydroxide solution as described below as a means for increasing the pH, by placing it downstream of the filtration means, deterioration of the filter material of the filtration means due to the high pH can be suppressed.

[0015] The pH of the flushing water may be increased to precipitate the dissolved zinc, and the precipitated zinc may be collected by the filtering means. Alternatively, the pH may be increased to enlarge the zinc particles in the flushing water, and the enlarged zinc may be collected by the filtering means.

[0016] From another perspective, the present invention is a method for treating flushing water from a piping system, characterized in that the pH of the flushing water is increased and the pH-increased flushing water is filtered by a filtering means. In this case, the pH of the flushing water may also be increased to a pH of 8 to 9.

[0017] The piping system may be a circulation system, and flushing may be carried out repeatedly until the turbidity of the flushing water reaches a predetermined value. In such a case, flushing may be terminated when the turbidity of the flushing water reaches a predetermined value. Alternatively, the turbidity may be measured at any time using a turbidity meter, and flushing may be terminated or an alert may be issued when the turbidity reaches a predetermined value. [Effects of the Invention]

[0018] According to the present invention, the dissolved zinc in the flushing water can be more reliably precipitated and collected by the filtration means than in the past, and fine zinc particles that could not be collected by the filtration means can be enlarged and collected by the filtration means, thereby making it possible to suppress the causes of corrosion more than in the past. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a system diagram of a flushing water treatment system according to a first embodiment. [Figure 2] 10 is a graph showing the results of an experiment investigating the relationship between pH and turbidity in flushing water. [Figure 3] FIG. 10 is a system diagram of a flushing water treatment system according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described. Fig. 1 shows an outline of the system of a flushing water treatment system 1 according to a first embodiment. In this system, chilled water produced by a chilled water maker 3 is supplied by a pump 4 to an air conditioning equipment, for example, an air handling unit 2. The chilled water, which has been heated after passing through the air handling unit 2, is returned to the chilled water maker 3.

[0021] The flushing water treatment system 1 according to the first embodiment is applied to such a circulation pipe 5. That is, the flushing water treatment system 1 according to the embodiment is provided in a pipe 10 connected in parallel to the circulation pipe 5.

[0022] The flushing water treatment system 1 has a filtration device 11 with a filter. Downstream of the filtration device 11, a pipe 10a connected in parallel to the pipe 10 is provided with an ion exchange resin 12 as a pH increasing means. Furthermore, upstream of the ion exchange resin 12 in the pipe 10a, a valve V1 is provided for opening and closing the pipe 10a.

[0023] Meanwhile, a pH sensor 13 is provided in the pipe 10 immediately downstream of the filtration device 11, and measures the pH of the water flowing through the pipe 10 immediately after passing through the filtration device 11. A valve V2 that opens and closes the pipe 10 is provided downstream of the pH sensor 13 in the pipe 10.

[0024] The opening and closing of valves V1 and V2 is controlled by a control device 14. The pH of the water detected by pH sensor 13 is output to the control device 14. Based on the output from pH sensor 13, the control device 14 opens and closes valves V1 and V2.

[0025] For example, if the value detected by the pH sensor 13 is smaller than a predetermined value, control is performed to open valve V1 and close valve V2, so that the water that has passed through the filtration device 11 is sent to the ion exchange resin 12 side, thereby raising the pH. On the other hand, if the value detected by the pH sensor 13 is larger than the predetermined value, control is performed to close valve V1 and open valve V2, so that the flushing water flows bypassing the ion exchange resin 12.

[0026] As mentioned above, the pH increasing means employed in this embodiment is the ion exchange resin 12. More specifically, a strong or weak basic anion exchange resin is used as the ion exchange resin 12 in this embodiment. This prevents an increase in salt concentration as mentioned above and simultaneously adjusts the pH.

[0027] The flushing water treatment system 1 according to the first embodiment has the above configuration, and when flushing the circulation pipe 5, the pipe 10 of the flushing water treatment system 1 is connected in parallel to the circulation pipe 5. Next, an appropriate valve (not shown) is operated so that the water flowing through the circulation pipe 5 flows to the pipe 10 side of the flushing water treatment system 1, thereby causing water to flow through the circulation pipe 5.

[0028] As a result, the water in the circulation pipe 5 flows into the filtration device 11 of the flushing water treatment system 1. The pH of the water purified by the filtration device 11 is measured by the pH sensor 13. The measurement result is output to the control device 14. The control device 14 switches the opening and closing of the valves V1 and V2 based on, for example, a preset pH threshold value.

[0029] For example, if the measured value is smaller than the threshold value, control is performed to open valve V1 and close valve V2, and the water that has passed through filtration device 11 is sent to ion exchange resin 12, thereby increasing the pH. As a result, the pH of the water treated by ion exchange resin 12 increases.

[0030] The threshold value can be, for example, pH 8 or higher, for example, pH 8 to 9. This allows the desired pH to be achieved in a shorter time than with conventional methods of increasing the pH as the situation dictates. Furthermore, since the pH can be set appropriately, it is possible to enlarge the zinc particles and reliably precipitate the dissolved zinc.

[0031] Incidentally, when flushing was performed using the conventional so-called filter method, the turbidity of the flushing water at the site did not decrease due to the turbidity of zinc particles. When the pH was adjusted using the pH increasing means as in the embodiment, the relationship between the pH value and turbidity was investigated. The results are shown in Figure 2.

[0032] This shows that the turbidity is lowest at a pH of 8, and then gradually increases as the pH increases. This is due to the characteristics of the metal dissolution amount, where the solubility decreases as the pH increases beyond the appropriate range. Therefore, in light of the object of the present invention, a pH of 8 to 9 can be cited as an example of a preferred pH for increasing the pH.

[0033] Based on these results, it was confirmed that turbidity can be reduced by adjusting the pH of the flushing water. Furthermore, because turbidity can be reliably reduced, measuring the change in turbidity makes it possible to accurately determine the completion time of flushing and automatically stop flushing.

[0034] Figure 3 shows an outline of the system of the flushing water treatment system 21 of the second embodiment, which was constructed from this perspective. In the figure, the components, configurations, and functions indicated with the same symbols as those of the flushing water treatment system 1 of the first embodiment shown in Figure 1 are essentially identical to those adopted in the flushing water treatment system 1 of the first embodiment.

[0035] The flushing water treatment system 21 according to the second embodiment is the same as the flushing water treatment system 1 according to the first embodiment, except that a turbidity meter 15 is further provided at the inlet side of the filtration device 11 to measure changes in turbidity. The turbidity of the water at the inlet side of the filtration device 11 detected by the turbidity meter 15 is output to the control device 14 every moment.

[0036] The flushing water treatment system 21 according to the second embodiment having such a configuration can predict the change in turbidity over time and the time required to reach a preset turbidity. Therefore, by determining the turbidity at which flushing should be stopped in advance, it is possible to predict the completion time of flushing and automatically stop flushing.

[0037] If the turbidity does not reach the preset level even after the predicted time has elapsed, a notification means such as a lamp or alarm may be provided to notify the user of this.

[0038] By the way, to increase the pH, for example, chemicals can be added to adjust the pH, making it possible to treat at the optimal pH. In this case, adding a sodium hydroxide solution, for example, can increase and adjust the pH. However, adding chemicals such as sodium hydroxide increases the salt concentration. An increase in salt concentration increases electrical conductivity, which in turn increases the risk of corrosion. Therefore, as a means of increasing pH, a method using ion exchange resins, which minimizes the increase in salt concentration as in the embodiment, is superior in terms of corrosion prevention. In addition, using chemicals to adjust the pH requires additional work, such as chemical management. In this respect, the method of increasing pH using ion exchange resins, which are easy to store, manage, and handle, is also advantageous. [Industrial Applicability]

[0039] The present invention is useful for treating flushing wastewater. [Explanation of symbols]

[0040] 1. Flushing water treatment system 2 Air Handling Unit 3 Cold water making machine 4 Pump 4 5 Circulation piping 10, 10a piping 11 Filtration equipment 12 Ion exchange resin 13 pH sensor 14 Control device 15 Turbidity meter V1 and V2 valves

Claims

1. 1. A system for treating flushing water from a piping system, comprising: The apparatus includes a filtering means for filtering the flushing water and a pH increasing means for increasing the pH of the flushing water, A flushing water treatment system, characterized in that the filtering means filters the flushing water whose pH has been increased by the pH increasing means.

2. 2. The flushing water treatment system according to claim 1, wherein the pH increasing means increases the pH of the flushing water to 8 to 9.

3. 2. The flushing water treatment system according to claim 1, wherein the flushing water before the pH is increased by the pH increasing means contains zinc that cannot be filtered out by the filtering means.

4. 4. The flushing water treatment system according to claim 1, wherein the pH increasing means is an ion exchange resin.

5. 4. The flushing water treatment system according to claim 1, wherein the pH increasing means is disposed downstream of the filtering means.

6. 4. The flushing water treatment system according to claim 1, wherein the pH of the flushing water is increased to precipitate the dissolved zinc in the flushing water, and the precipitated zinc is collected by the filtering means.

7. A flushing water treatment system according to any one of claims 1 to 3, wherein the pH is increased to enlarge zinc particles in the flushing water, and the enlarged zinc is collected by the filtering means.

8. 1. A method for treating flush water from a piping system, comprising: A flushing water treatment method, comprising increasing the pH of the flushing water and filtering the pH-increased flushing water with a filtering means.

9. 9. The flushing water treatment method according to claim 8, wherein the piping system is a circulating system, and flushing is repeated until the turbidity of the flushing water reaches a predetermined value.

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