Pipe cleaning device and method

Abstract

To easily install a flushing device in a piping system, shorten the time required for flushing, and reduce the amount of drainage. [Solution] A cleaning device 1 used for flushing a piping system P. It is composed of a strainer 6 connected to the piping system P and incorporating a screen 9, a single-structure filter 12 that is attached inside the screen 9 during flushing and is composed only of a relatively coarse-mesh filter, and a composite-structure filter 14 that is composed of a combination of a relatively coarse-mesh filter and a relatively fine-mesh filter, and is switchable between a state in which flushing is performed with the single-structure filter 12 attached inside the screen 9 and a state in which flushing is performed with the composite-structure filter 14 attached inside the screen 9.

Description

[Technical field]

[0001] The present invention relates to a cleaning device and a cleaning method used for cleaning (flushing) a piping system of a heat source device or an air conditioner before a test run of the device. [Background technology]

[0002] Flushing of piping systems in building facilities is carried out at construction sites to remove sludge (impurities) remaining in the piping, such as soil and dust that flowed into the piping during temporary placement or transportation due to poor protection of the piping ends, welding slag generated during pipe welding work, metal chips generated during thread processing work, etc. If this flushing is insufficient, it may cause corrosion of air conditioning piping, blockage of strainers, damage to equipment, etc.

[0003] Conventional flushing involves repeatedly filling the pipes with water, circulating the water, and draining the water until the water quality in the pipes reaches the target quality, as shown in Figure 20. However, this method has problems such as the long flushing time and the large amount of wastewater generated.

[0004] As a simple flushing method, a method using a strainer is also known. A strainer is a filtering device that uses a built-in screen with a certain mesh size to capture sludge in the fluid flowing through the piping. However, it is not possible to capture sludge with a particle size smaller than the mesh size of the built-in screen, and such small-particle sludge must be drained from a drain pipe separately installed in the piping system and removed together with the drainage. Therefore, in addition to the long time required for draining and refilling with water, problems such as the use of large amounts of water have been a problem.

[0005] In recent years, as disclosed in Patent Document 1 and Non-Patent Document 1 below, a method has been proposed in which a temporary water treatment device is connected to the piping system as a bypass and the water is treated by this water treatment device.

[0006] The following Patent Document 1 discloses a system in which a temporary water treatment device equipped with a pump is connected to a flushing piping system as a bypass, and part of the circulating water is transported to a water treatment unit and returned to the flushing piping system after treatment.

[0007] Furthermore, the following non-patent document 1 discloses a system in which a temporary water treatment device (bag filter) is connected to a flushing piping system via a bypass, a valve is provided in the piping system, and by operating this valve, the entire amount of flushing water is transported to a water treatment device and returned to the flushing piping system after treatment. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 6524032 [Non-patent literature]

[0009] [Non-Patent Document 1] Iida et al., A Study on the Completion Criteria for Flushing Closed Air Conditioning Piping, Proceedings of the Society of Heating, Air-Conditioning and Sanitary Engineers of Japan Annual Conference (September 16-18, 2015), pp. 241-243, 2015 Summary of the Invention [Problem to be solved by the invention]

[0010] However, in the method of bypass connection of a temporary water treatment device as disclosed in the above Patent Document 1 and Non-Patent Document 1, it is necessary to consider in advance the location where the water treatment device is to be installed and the method of carrying it in and out, and there are problems such as restrictions on the installation of the water treatment device and the long time required to install the water treatment device. Also, if the diameter of the bypass piping is smaller than the diameter of the piping of the flushing piping system, the water treatment flow rate decreases, making it difficult to say that efficient cleaning can be performed.

[0011] SUMMARY OF THE PRESENT EMBODIMENTS Accordingly, a primary object of the present invention is to provide a piping system cleaning device and cleaning method which can be easily installed in a piping system, can shorten the time required for flushing, and can reduce the amount of wastewater. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention according to claim 1 provides a cleaning device used for flushing a piping system, comprising: The filter comprises a strainer connected to the piping system and having a built-in screen, a single-piece filter that is attached to the inside of the screen during flushing and is composed of only a relatively coarse filter, and a composite filter that is composed of a combination of a relatively coarse filter and a relatively fine filter, A piping system cleaning device is provided, which is characterized in that it is switchable between a state in which the single-structure filter is attached inside the screen and flushing is performed, and a state in which the composite structure filter is attached inside the screen and flushing is performed.

[0013] In the invention described in claim 1, a strainer is connected to a piping system, and a filter is attached inside a screen built into the strainer to capture sludge in the fluid in the piping system. As the filter attached inside the screen, flushing can be performed by switching between a single-structure filter composed only of a relatively coarse filter and a composite-structure filter composed of a combination of a relatively coarse filter and a relatively fine filter. Therefore, by first attaching the single-structure filter and performing flushing, and then attaching the composite-structure filter and performing flushing, sludge in the fluid can be efficiently removed.

[0014] In this way, the cleaning device of the present invention can be easily installed by utilizing a strainer connected to the piping system, without using a large-scale external water treatment device, and since the sludge in the fluid is collected by circulating the water and passing it through the strainer, flushing can be performed without repeatedly filling and draining the water, shortening the time required for filling and draining the water and reducing the amount of wastewater.

[0015] According to a second aspect of the present invention, there is provided a piping cleaning device as defined in the first aspect, wherein the strainer is a Y-strainer, a T-strainer or a straight strainer having a cylindrical screen built-in.

[0016] In the invention described in claim 2, a Y-shaped strainer, a T-shaped strainer, or a straight strainer with a built-in cylindrical screen is used as the strainer. Here, specific examples of the main types of strainers used in building facilities are given, and it is also possible to configure the cleaning device according to the present invention using a strainer with a built-in cylindrical screen other than these.

[0017] According to a third aspect of the present invention, there is provided the piping cleaning device of the first aspect, wherein the single-piece filter is formed by rolling a filter sheet into a roll from one end.

[0018] The invention described in claim 3 above prescribes a specific structure of the single-piece filter, and is configured by rolling a flat filter sheet from one end into a roll.

[0019] As the present invention according to claim 4, there is provided a piping cleaning device as described in claim 1, in which the composite structure filter is configured by winding an outer filter made of a relatively fine-mesh filter sheet around the outer circumference of an inner filter made of a relatively coarse-mesh filter sheet rolled from one end into a roll.

[0020] In the invention described in claim 4 above, if a fine-mesh filter is packed inside the screen, the pressure difference before and after the strainer will become large, which may cause the screen to be damaged or the circulation flow rate to be insufficient, preventing the sludge inside the piping system from being transported. Therefore, a composite structure filter is formed by wrapping a relatively fine-mesh filter around the outer circumference of a relatively coarse-mesh filter.

[0021] The present invention according to claim 5 provides a piping cleaning device as described in claim 1, in which the single-structure filter and the composite-structure filter are each mounted inside the screen and arranged to fill the inside of the screen.

[0022] In the invention described in claim 5 above, the single-structure filter and the composite-structure filter are each mounted inside the screen and arranged so that each filter is filled inside the screen, so that the fluid in the piping system reliably passes through the filters and is purified.

[0023] The present invention according to claim 6 provides a cleaning device as described in claim 1, in which a cylindrical spacer having both ends open and a number of through holes formed on its circumferential surface is disposed in the center of at least one of the single-structure filter and the composite-structure filter, thereby reducing pressure loss.

[0024] In the invention described in claim 6, a hollow cylindrical spacer is disposed in the center of at least one of the single-structure filter and the composite-structure filter, so that the pressure loss before and after the strainer can be further reduced.

[0025] According to a seventh aspect of the present invention, there is provided a cleaning method for use in flushing a piping system, comprising the steps of: A strainer having a built-in screen is connected to the piping system, a first step of circulating a fluid through the piping system in a state where a single-piece filter composed only of a relatively coarse filter is installed inside the screen; The present invention provides a method for cleaning a piping system, which comprises a second step of replacing the filter installed inside the screen with a composite structure filter composed of a combination of a relatively coarse filter and a relatively fine filter, and circulating a fluid through the piping system.

[0026] In the invention described in claim 7 above, flushing is performed in a first step of circulating the fluid through the piping system with the single-structure filter attached inside the screen of a strainer connected to a piping system, and a second step of replacing the filter attached to the screen with the composite structure filter and circulating the fluid through the piping system. Therefore, no large-scale external water treatment device is required, and the device can be easily installed by utilizing the strainer connected to the piping system. In addition, sludge can be captured in the strainer simply by circulating water without repeatedly filling and draining the water, thereby shortening the time required for flushing and reducing the amount of wastewater.

[0027] The present invention according to claim 8 provides a method for cleaning a piping system as described in claim 7, which, if the cleanliness does not satisfy the target value at the stage when the second step is completed, performs a third step of supplying water from a water supply pipe connected to the piping system and draining water from a water drain pipe connected to the piping system, and performing a water exchange process on the flushing water until the target cleanliness is achieved.

[0028] In the invention described in claim 8 above, after the first and second steps of capturing sludge by circulating water through a filter attached inside the screen of a strainer, only if the cleanliness does not satisfy the target value at the stage when the second step is completed is the third step of replacing the flushing water by supplying water from the water supply pipe and draining it from the water drain pipe, so that the amount of fresh water injected into the piping system can be reduced compared to the conventional method in which water is supplied and drained from the early stage of flushing.

[0029] The present invention according to claim 9 provides the method for cleaning a piping system according to claim 7, wherein the water circulation in the first and second steps is performed so that the fluid circulates through the piping system approximately 20 to 40 times, respectively.

[0030] In the invention described in claim 9 above, the results of preliminary tests revealed that the gradient of decrease in cleanliness is large immediately after the start of water circulation, but that the gradient of decrease in cleanliness becomes almost zero once the number of circulations reaches a certain level (20 to 40 or more).Therefore, a decision is made to end the process and move on to the next process when the number of circulations reaches 20 to 40, at which point the gradient of decrease in cleanliness becomes almost zero. Effect of the Invention

[0031] As described above in detail, according to the present invention, the device can be easily installed in a piping system, the time required for flushing can be shortened, and the amount of drainage can be reduced. [Brief description of the drawings]

[0032] [Figure 1] 1 is a system diagram of a piping system P in which a piping system cleaning device 1 according to the present invention is arranged. [Diagram 2] FIG. 2 is a cross-sectional view of a strainer 6. [Diagram 3] 1 is a diagram showing how to attach a single-structure filter 12 to a screen 9. FIG. [Figure 4] 1 is a diagram showing how to attach a composite structure filter 14 to a screen 9. FIG. [Diagram 5] FIG. 2 is a perspective view showing a composite structure filter 14 in which a cylindrical spacer 15 is arranged. [Figure 6] FIG. 2 is a flow chart showing a piping cleaning method according to the present invention. [Figure 7] FIG. 1 is a piping plan view showing an experimental device. [Figure 8] 8 is a cross-sectional view taken along line VIII-VIII in FIG. 7. [Figure 9] 9 is a view taken along line IX-IX in FIG. 7. [Figure 10]4 is a graph showing the evaluation results of the removal performance of the single-piece structure filter 12. [Figure 11] 1 is a graph showing the comparison results of the removal performance of each filter. [Figure 12] 4 shows the pressure loss curves of each filter. [Figure 13] 4 shows the pressure loss curves of each filter. [Figure 14] 13 is a graph showing the results of a comparison of removal performance with and without a cylindrical spacer 15. [Figure 15] This is a piping diagram around the air conditioning device 3 used in the actual equipment experiment. [Figure 16] 13 is a graph showing a comparison result of flushing operation time of a hot and cold water system. [Figure 17] 13 is a graph showing a comparison result of flushing operation time in a reheat hot water system. [Figure 18] 11 is a graph showing a comparison result of the amount of drainage in a flushing operation. [Figure 19] 1 is a graph showing the change in turbidity of flushing water when the present invention is carried out. [Figure 20] FIG. 1 is a flow chart showing a conventional flushing procedure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0034] [Pipe cleaning device 1] The piping system cleaning device 1 according to the present invention can be applied to all piping systems used in normal air conditioning equipment. As an example of such a piping system P, as shown in Fig. 1, there is one that is composed of a heat source device 2 installed outdoors, an air conditioning device 3 installed indoors, and a cold / heat medium piping 4 connected to them and through which a heat medium fluid is circulated by a pump or the like. As the cold / heat medium piping 4, a cold / heat medium piping, a cooling water piping, a reheated hot water piping, and the like may be arranged as independent piping systems. In addition, a gate valve 5 is provided on the inlet side and outlet side of the heat source device 2 and the air conditioning device 3 of the cold / heat medium piping 4, respectively.

[0035] A strainer 6 is provided on the upstream side of each device to prevent damage to the heat source device 2, the air conditioning device 3, and devices such as the pump and the heat exchange coil due to sludge mixed in with the fluid flowing through the piping system P. In the example shown in Fig. 1, the strainer 6 is provided in the piping on the inlet side of the heat source device 2.

[0036] A wide variety of well-known strainers can be used as the strainer 6, and as shown in Fig. 2, the strainer is composed of a hollow main body 7 having an inlet and an outlet, and a capture section 8 that communicates with the middle section of the main body 7 and has a screen 9 with a large number of openings for capturing sludge in the fluid. The capture section 8 is provided with an outlet through which the built-in screen 9 can be removed, and this outlet is closed by a lid 10.

[0037] The flow of fluid within the strainer 6 is such that the fluid flows into the main body 7 from the inlet, flows into the inside of the screen 9 from the upper opening of the screen 9, passes through a number of through holes formed on the peripheral surface and bottom surface of the screen 9, and flows out of the screen 9, and then flows out from the outlet of the main body 7.

[0038] The strainer 6 may be of various shapes, such as a Y-shaped strainer, a T-shaped strainer, a straight strainer, or a U-shaped strainer, and any of these may be used, but it is preferable to use a strainer that allows the screen 9 to be easily attached and detached.

[0039] The screen 9 is formed in a cylindrical shape with one end open and a bottom, and is made of punching metal, wire mesh, wedge wire, etc., so that a large number of through holes are provided on both the periphery and the bottom. The mesh size of the screen 9 is determined by the size of the through holes, with smaller mesh sizes being able to capture small foreign objects, and larger mesh sizes being able to capture only large foreign objects. The mesh size may be within the range of commonly used sizes, but it is preferable to use wire mesh with an opening size of about 40 mesh as specified in JIS G 3555 and JIS G 3556, with reference to the standard specifications for public building construction.

[0040] The cleaning device 1 of the present invention comprises the strainer 6, a single-structure filter 12 which is mounted inside the screen 9 during flushing and which is composed only of a relatively coarse-mesh filter (coarse filter sheet 11), and a composite-structure filter 14 which is composed of a combination of a relatively coarse-mesh filter (coarse filter sheet 11) and a relatively fine-mesh filter (dense filter sheet 13), and is switchable between a state in which the single-structure filter 12 is mounted inside the screen 9 and flushing is performed, and a state in which the composite-structure filter 14 is mounted inside the screen 9 and flushing is performed.

[0041] The single-piece filter 12 is a filter formed by a single relatively coarse filter sheet 11, and is formed so that the material composition and porosity are almost constant throughout the filter. The coarse filter sheet 11 can be made of porous materials such as nonwoven fabric, woven fabric, and sponge, but it is preferable to use a nonwoven fabric that can stably set the porosity and has good sludge collection efficiency. The material fibers constituting the nonwoven fabric can be any one or a combination of two or more of synthetic fibers such as olefins, polyesters, and polyamides such as polyethylene or polypropylene, regenerated fibers such as rayon and cupra, semi-synthetic fibers such as acetate, and natural fibers such as cotton, and nonwoven fabrics obtained by appropriate processing methods such as spunlace, spunbond, thermal bond, meltblown, and needle punch can be used.

[0042] 3(A), the single-piece filter 12 is formed by forming a roughly rectangular, flat-plate-like coarse filter sheet 11 having long and short sides into a predetermined shape. The length of the short side of the coarse filter sheet 11 is roughly equal to the height (axial length) of the screen 9.

[0043] The single-piece filter 12 is formed by rolling the coarse filter sheet 11 in a roll shape by rolling it from one end of the short side in the long side direction into a generally cylindrical shape (Figs. 3(B) and (C)), which is inserted into the screen 9 for use (Fig. 3(D)). It is preferable to form the outer diameter of the single-piece filter 12 to be approximately the same as the inner diameter of the screen 9, or to form the outer diameter of the single-piece filter 12 to be slightly larger than the inner diameter of the screen 9, so that when the single-piece filter 12 is attached inside the screen 9, there is no gap between the single-piece filter 12 and the screen 9 and the two are filled together. When the coarse filter 11 is wound into a roll, and when the rolled single-structure filter 12 is inserted into the screen 9, no compressive force that would drastically reduce the porosity of the coarse filter sheet 11 is applied to the single-structure filter 12, and in the process of forming the roll-shaped single-structure filter 12 from the coarse filter sheet 11 and fitting it into the screen 9, the porosity is hardly reduced, or the porosity of the outer periphery is slightly reduced when the single-structure filter 12 is inserted into the screen 9. However, the reduction in porosity is 20 points or less, preferably 10 points or less, compared to the porosity of the original coarse filter sheet 11.

[0044] The coarse filter sheet 11 is made of fibers having an average fiber diameter of 50 to 200 μm, preferably 80 to 120 μm, a thickness of 5 to 50 mm, preferably 10 to 30 mm, and a porosity of 70 to 99%, more preferably 93 to 99%. The average fiber diameter can be obtained by the average value of each fiber diameter measured from an image of a plurality of points magnified and photographed with an electron microscope, the thickness can be obtained according to the A method of the thickness test of the JIS L 1913 general nonwoven fabric test method, and the porosity can be obtained from (100-(weight / volume) / fiber specific gravity). The weight can be obtained by multiplying the value measured according to the mass per unit area test of the JIS L 1913 general nonwoven fabric test method by the area, the volume can be obtained by multiplying the thickness by the area, and the fiber specific gravity can be obtained by the specific gravity of the chemical fiber filament yarn test method specified in JIS L 1013.

[0045] Next, the composite structure filter 14 is a filter configured by combining a relatively coarse filter sheet 11 and a relatively fine filter sheet 13, and configured so that the porosity is smaller on the outer periphery side than on the center of the filter. The coarse filter sheet 11 can be the same as that used in the single-piece structure filter 12.

[0046] As the dense filter sheet 13, porous materials such as nonwoven fabric, woven fabric, and sponge can be used, as in the case of the coarse filter sheet 11, but it is preferable to use nonwoven fabric that can stably set the porosity and has good sludge collection efficiency. The material fibers constituting the nonwoven fabric can be any one or a combination of two or more of synthetic fibers such as olefins such as polyethylene or polypropylene, polyesters, and polyamides, regenerated fibers such as rayon and cupra, semi-synthetic fibers such as acetate, and natural fibers such as cotton, and nonwoven fabrics obtained by appropriate processing methods such as spunlace method, spunbond method, thermal bond method, meltblown method, and needle punch method can be used.

[0047] As shown in Fig. 4(A), the composite structure filter 14 is formed by rolling up an approximately rectangular flat coarse filter sheet 11 having long and short sides in the long side direction from one end of the short side into a roll to form an inner filter processed into an approximately cylindrical shape, and then winding and laminating an outer filter made of a dense filter sheet 13 around the outer periphery of the inner filter (Fig. 4(B)), and inserting this into the screen 9 for use (Fig. 4(C)). The outer diameter of the composite structure filter 14 and the inner diameter of the screen 9 are preferably formed to be approximately the same size, or the outer diameter of the composite structure filter 14 is formed to be slightly larger than the inner diameter of the screen 9, so that when the composite structure filter 14 is attached inside the screen 9, there is no gap between the composite structure filter 14 and the screen 9 and the gap is filled. When the coarse filter sheet 11 is wound into a roll, when the dense filter sheet 13 is wound and laminated around the outer periphery of the rolled coarse filter sheet 11, and when the composite-structure filter 14 is inserted into the screen 9, no compressive force that would drastically reduce the porosity of the coarse filter sheet 11 and the dense filter sheet 13 is applied to the composite-structure filter 14, and in the process of forming the composite-structure filter 14 and fitting it into the screen 9, the porosity is hardly reduced, or the porosity of the outer periphery is slightly reduced when the composite-structure filter 14 is inserted into the screen 9. However, the reduction in porosity is 20 points or less, preferably 10 points or less, compared to the porosity of the original coarse filter sheet 11 and dense filter sheet 13.

[0048] The dense filter sheet 13 is made of fibers having an average fiber diameter of 1 to 49 μm, preferably 20 to 40 μm, a thickness of 5 to 50 mm, preferably 10 to 30 mm, and a porosity of 70 to 99%, more preferably 93 to 99%. The average particle diameter, thickness, and porosity are determined as described above. The dense filter sheet 13 uses fibers having a smaller average fiber diameter than the coarse filter sheet 11, and therefore has a finer mesh than the coarse filter sheet 11.

[0049] The dense filter sheet 13 may be wound in multiple layers around the outer periphery of the rolled-up coarse filter sheet 11, but it is preferable to wind only one layer. The dense filter sheet 13 has finer mesh than the coarse filter sheet 11, which may increase pressure loss and reduce the water circulation flow rate, and there is a risk of damage to the screen 9 due to clogging of the filter, so it is preferable to wind one layer.

[0050] As shown in Fig. 5, a cylindrical spacer 15 with both ends open and a large number of through holes formed on the circumferential surface may be disposed in the center of the composite filter 14 to reduce pressure loss. As a result of an experiment described later, by disposing the cylindrical spacer 15 in the center of the composite filter 14, pressure loss is significantly reduced and sludge removal efficiency can be improved. Note that Fig. 5 shows an example in which the cylindrical spacer 15 is provided in the composite filter 14, but the cylindrical spacer 15 can be provided in at least one of the single-piece filter 12 and the composite filter 14.

[0051] The cylindrical spacer 15 is made of punching metal, wire mesh, or wedge wire, and has a large number of through holes formed on its peripheral surface. The cylindrical spacer 15 has approximately the same height (axial length) as the screen 9, and is disposed at the center of the hollow interior of the screen 9. Nothing is disposed in the hollow portion of the cylindrical spacer 15, leaving it hollow, and the single-structure filter 12 or composite-structure filter 14 is disposed between the outer peripheral surface of the cylindrical spacer 15 and the inner peripheral surface of the screen 9.

[0052] When the unitary structure filter 12 is disposed on the outer periphery of the cylindrical spacer 15, the coarse filter sheet 11 is wound around the outer periphery of the cylindrical spacer 15 in one or more layers.

[0053] On the other hand, when arranging the composite structure filter 14 on the outer periphery of the cylindrical spacer 15, the coarse filter sheet 11 is wound around the outer periphery of the cylindrical spacer 15, and then the dense filter sheet 13 is wound around the outer periphery of the coarse filter sheet 11. The coarse filter sheet 11 and the dense filter sheet 13 may be wound in one layer or multiple layers, but in order to prevent an increase in pressure loss, it is preferable to wind at least the dense filter sheet 13 in one layer, and it is particularly preferable to wind both the coarse filter sheet 11 and the dense filter sheet 13 in one layer. This ensures that cleaning can be performed without increasing the pressure loss in the cleaning device 1.

[0054] The inner diameter of the cylindrical spacer 15 can be appropriately determined depending on the inner diameter of the screen 9, the thickness of the coarse filter sheet 11 and the dense filter sheet 13, the number of windings, and the thickness of the cylindrical spacer 15. For example, when the inner diameter of the screen 9 is 80 mm, and the coarse filter sheet 11 having a thickness of 20 mm and the dense filter sheet 13 having a thickness of 18 mm are wound in one layer (total thickness of both is 38 mm), if the thickness of the cylindrical spacer 15 is 2 mm, the inner diameter of the cylindrical spacer 15 can be 40 mm. In this case, the spatial ratio of the area of ​​the hollow part of the cylindrical spacer 15 to the internal area of ​​the screen 9 in the cross-sectional view of the screen 9 is 39.1%.

[0055] The aperture ratio of the numerous through holes provided on the circumferential surface of the cylindrical spacer 15 (the ratio of the total area of ​​the through holes to the inner circumferential area of ​​the cylindrical spacer 15) is preferably 30 to 50%.

[0056] [Method for cleaning piping system] Next, a method for flushing the piping system P using the cleaning device 1 will be described with reference to FIG.

[0057] As described above, the piping system P is connected to the strainer 6 having the built-in screen 9.

[0058] In the first step, the single-piece filter 12 is attached to the screen 9 in advance, and the piping system P is filled with water and air is removed as needed.

[0059] Thereafter, with the single-piece filter 12 attached inside the screen 9, the pump is operated to circulate the fluid through the piping system P. The water circulation in the first step is performed so that the fluid circulates through the piping system P 20 to 40 times. In other words, the water circulation is performed continuously for the circulation time obtained from the formula: Circulation time = (water volume held in the piping system P / flow rate) x 20 to 40. As a result, the fluid passes through the cleaning device 1 20 to 40 times during the water circulation, and sludge present in the fluid is captured by the single-piece filter 12 of the cleaning device 1 during that time.

[0060] Regarding the water circulation flow rate during flushing, referring to a previous report (Umehara, Shinada, Takatsuka, "Flow rate required to remove foreign objects from inside the piping", Shin-Nihon Air Conditioning Technology Development Research Institute Technical Report No. 27, pp. 51-54 (2021)), it is recommended to adjust the pump frequency with a flow rate of 0.7 m / s or more as a guideline. This water circulation flow rate is also the same for the second process in the next step.

[0061] The decision to end the first step is made based on whether the turbidity measurement results have converged to the first order, with the number of circulations being approximately 20 to 40. In other words, the gradient of turbidity reduction is large immediately after the start of water circulation, but the results of preliminary tests have revealed that once the number of circulations reaches a certain level (20 to 40 or more), the gradient of turbidity reduction becomes nearly zero (first order convergence). Therefore, a decision is made to end the first step and move on to the second step when the number of circulations reaches the first order, which is between 20 and 40.

[0062] It is preferable to measure the turbidity when the water filling is completed before the water circulation, and also to measure the turbidity when the first step is completed.

[0063] Next, if it is determined in the first step that the turbidity has converged to the first stage, the process proceeds to the second step. In the second step, the pump is stopped and the valves before and after the strainer 6 are closed, and then the cover 10 of the strainer 6 is opened and the screen 9 is removed. Next, the single-piece filter 12 is removed from inside the screen 9 and, after appropriate cleaning, the composite filter 14 is attached inside the screen 9.

[0064] Once the composite structure filter 14 is installed inside the screen 9, the screen 9 is attached to the strainer 6, the valves before and after the strainer 6 are opened, and the pump is restarted to circulate the fluid through the piping system.

[0065] The second step is terminated when the number of circulations is approximately 20 to 40, similarly to the first step, based on whether the turbidity measurement results have converged to the second order or not.

[0066] At the end of this second step, the turbidity is measured.

[0067] If the turbidity at the end of the second step satisfies the target value, the composite structure filter 14 is removed from inside the screen 9, the screen 9 is cleaned, and then returned to the inside of the strainer 6, thereby completing the flushing.

[0068] If the turbidity at the end of the second step does not satisfy the target value, the third step is performed by simultaneously supplying water from the water supply pipe 16 connected to the piping system P and draining water from the water drain pipe 17 connected to the piping system P, and exchanging the flushing water until the turbidity reaches the target value. This step is performed until the turbidity satisfies the target value while measuring the turbidity at appropriate times along the way. This third step is performed as necessary, and does not need to be performed if the turbidity satisfies the target value at the end of the second step. By performing the third step, the turbidity can be reliably made to satisfy the target value. In addition to turbidity, any index such as color or transparency that can determine the cleanliness of the liquid may be used as the index for determining the completion of flushing.

[0069] In the present invention, after the above-mentioned first and second steps of circulating water by installing filters 12, 14 inside screen 9 of strainer 6 to capture sludge in the fluid, only if the turbidity does not satisfy the target value at the end of the second step is the third step of exchanging the flushing water by simultaneously supplying water from the water supply pipe 16 and draining water from the water drain pipe 17, so that the amount of fresh water injected into the piping system can be greatly reduced compared to the conventional method in which water is supplied and drained from the early stage of flushing. In other words, even if the target turbidity is required strict, the amount of fresh water used for flushing the piping system P can be minimized.

[0070] In the third step, methods of simultaneously supplying water from the water supply pipe 16 and draining water from the water drain pipe 17 can be considered, such as a method in which fresh water is injected while circulating the fluid in the piping system P with a pump, diluting the water while draining it, or a piston flow replacement method in which fresh water is injected from one side while draining water from the other side with the pump stopped. Either method can be used, but the latter replacement method has the advantage that when fresh water is injected from one side of the piping system P and drained from the other side, a sudden drop in turbidity can be detected when the replacement is completed, making it easier to determine when flushing is complete. EXAMPLES

[0071] [Performance evaluation experiment of cleaning device 1] As shown in Figs. 7 to 9, an experiment was carried out to evaluate the performance of the cleaning device 1 according to the present invention using a simple circulation type piping system P.

[0072] The piping system P used in the experiment has two water tanks 20, 21, as shown in Figures 7 and 8, and water supply pipes 22, 23 through which water is supplied from the water tanks are connected to each water tank via water supply valves 24, 25, and water return pipes 26, 27 through which water is returned to the water tanks are connected via water return valves 28, 29. As shown in Figures 7 to 9, a flow path is formed in which water from the water supply pipes 22, 23 passes through the cleaning device 1, flow meter 30, and pump 31, and then returns to the water return pipes 26, 27. Valves 32, 33 are provided before and after the cleaning device 1.

[0073] In the experiment, foreign matter classified by particle size was put into one of the water tanks, the water from the one water tank was passed through the piping system P to return to the other water tank, and then the water from the other water tank was passed through the piping system P to return to the one water tank. This operation was repeated a predetermined number of times. More specifically, after the foreign matter was put into the water tank 20, the water supply valve 24 provided on the water supply pipe 22 of the water tank 20 was opened, the water supply valve 25 provided on the water supply pipe 23 of the water tank 21 was closed, the water return valve 28 provided on the water return pipe 26 of the water tank 20 was closed, and the water return valve 29 provided on the water return pipe 27 of the water tank 21 was opened. In this state, the pump 31 was operated, and the water in the water tank 20 passed through the cleaning device 1 through the water supply pipe 22, and then passed through the water return pipe 27 to be stored in the water tank 21. This process was repeated until the water in the water tank 20 was empty. Next, the water supply valve 24 provided on the water supply pipe 22 of the water tank 20 is closed, the water supply valve 25 provided on the water supply pipe 23 of the water tank 21 is opened, the return water valve 28 provided on the return water pipe 26 of the water tank 20 is opened, and the return water valve 29 provided on the return water pipe 27 of the water tank 21 is closed. In this state, the water in the water tank 21 passes through the cleaning device 1 through the water supply pipe 23, and then passes through the return water pipe 26 and is stored in the water tank 20. This process is repeated 20 times, with the above two processes counted as one time, to evaluate the removal performance of the cleaning device 1. In other words, by repeating the above process 20 times, the water in the piping system P passes through the cleaning device 1 40 times. When replacing the filter in the cleaning device 1, the built-in screen 9 is removed with the front and rear valves 32 and 33 in a closed state.

[0074] The particle diameter of the introduced foreign matter was known for five stages: less than 53 μm, 53 μm or more and less than 100 μm, 100 μm or more and less than 250 μm, 250 μm or more and less than 425 μm, and 425 μm or more. Hereinafter, the particle diameter ranges are expressed as less than 53 μm, 53 to 100 μm, 100 to 250 μm, 250 to 425 μm, and 425 μm or more for convenience. In addition, when conducting an experiment to evaluate the efficiency of removing fine particle diameter foreign matter, the particle diameter of the foreign matter was known for two stages: 32 μm or more and less than 63 μm, and 63 μm or more and less than 125 μm. Hereinafter, these are also expressed as 32 to 63 μm and 63 to 125 μm for convenience.

[0075] First, the experiment was carried out by mounting the unitary filter 12 according to the present invention to the cleaning device 1. The coarse filter sheet 11 constituting the unitary filter 12 had an average fiber diameter of 100 μm, a thickness of about 20 mm, and a porosity of 95%.

[0076] The results of the experiment are shown in Fig. 10. As a comparative example (without filter), the figure also shows the case where the single-piece structure filter 12 is not attached to the screen 9, and only the screen 9 is used.

[0077] Without a filter, the removal performance depends on the mesh size of the screen 9. Therefore, although the removal efficiency is poor, it is possible to remove foreign matter with a particle size of 425 μm or more. However, foreign matter with a particle size smaller than that is hardly removed at all.

[0078] In contrast, it was confirmed that the cleaning device 1 equipped with the single-piece structure filter 12 had a high efficiency in removing foreign matter having a particle diameter of 100 μm or more.

[0079] Next, the above-mentioned experiment was carried out by mounting the single-structure filter 12 similar to that described above, the composite structure filter 14 according to the present invention, and a fine mesh filter (comparative example) in which an external fine mesh filter was wound around the outer periphery of the single-structure filter 12, in the cleaning device 1. The foreign matter introduced was that used for evaluating the removal efficiency of fine foreign matter.

[0080] The coarse filter sheet 11 constituting the composite structure filter 14 was the same as described above, and the dense filter sheet 13 had an average fiber diameter of 30 μm, a thickness of about 18 mm, and a porosity of 95%. The fine filter used as a comparative example was prepared by wrapping an external sheet having an average fiber diameter of 25 μm, a thickness of about 0.15 mm, and a porosity of 60% in a single layer around the outer periphery of the coarse filter sheet 11 described above.

[0081] The results of the experiment are shown in Figure 11. It was confirmed that the composite structure filter 14 can remove foreign matter with smaller particle diameters than the single-piece structure filter 12. In addition, when the fine mesh filter is used, it shows removal performance equal to or greater than that of the composite structure filter 14, but has the disadvantage of increased pressure loss, as will be described later.

[0082] Next, pressure gauges were placed before and after the strainer 6 to measure the pressure loss caused by passing through the strainer 6. The results are shown in Fig. 12. As a comparative example (without a filter), the figure also shows the case where no filter is attached to the screen 9, and only the screen 9 is used.

[0083] The pressure loss is greater when the single-structure filter 12 and the composite-structure filter 14 are installed compared to when no filter is used. Also, the pressure loss is greater with the composite-structure filter 14 than with the single-structure filter 12. When the fine filter is installed, the pressure loss becomes so large that there is concern that the screen 9 may be damaged, and there is also concern that the water circulation flow rate may be insufficient, making it easier for foreign matter to become lodged inside the piping.

[0084] Next, the pressure loss was measured before and after the strainer 6 when the cylindrical spacer 15 was placed in the center of the single-structure filter 12 and the composite-structure filter 14. In addition, the removal efficiency of the composite-structure filter 14 was also measured when the cylindrical spacer 15 was not installed and when it was installed.

[0085] As a result, as shown in Fig. 13, the pressure loss before and after the strainer 6 was significantly reduced by installing the cylindrical spacer 15. For example, in the case of a flow velocity of 1.5 m / s, the pressure loss increases by about 60 kPa by inserting the composite structure filter 14 compared to without a filter, but by providing the cylindrical spacer 15, the increase in pressure loss is suppressed to about 20 kPa compared to without a filter, and a pressure reduction of 40 kPa (about 67%) was achieved. Also, as shown in Fig. 14, the provision of the cylindrical spacer 15 resulted in improved removal performance in the particle size range of 32 to 63 µm.

[0086] [Evaluation of cleaning method on actual equipment] Next, the cleaning device 1 according to the present invention was applied to flushing of air conditioning equipment piping at an actual construction site, and a comparative verification was carried out with respect to the work time and amount of drainage compared with conventional flushing (the method shown in Fig. 20). The construction site was an office building with 13 floors above ground, and as shown in Fig. 1, an air-cooled heat pump chiller with a built-in pump was installed on the roof as heat source equipment 2, and air conditioning equipment 3 was installed on each floor. The actual equipment experiment was carried out on a hot and cold water system (water capacity of 3.5 m 3 ), reheat hot water system (water capacity 2.6m 3 ) was performed.

[0087] FIG. 15 shows a piping diagram around the air conditioner 3. In conventional flushing, as shown in FIG. 20, water filling and blowing are performed two to three times as a pre-process of water circulation to remove foreign matter in the piping to some extent in advance. However, in the present invention, such a pre-process of water circulation is not performed, so if the water in the piping system P is circulated to the air conditioner 3 from the beginning, foreign matter in the piping system P may flow into the coil of the air conditioner 3, which may lead to damage to the coil. For this reason, in the actual machine experiment, a temporary bypass pipe 40 is connected between the supply pipe and the return pipe connected to the air conditioner 3, and a closing flange 41 is attached to each of the supply pipe and the return pipe connected to the air conditioner 3, so that the water in the piping system P flows directly from the supply pipe to the return pipe through the bypass pipe 40 without flowing into the air conditioner 3.

[0088] The actual experiment was carried out according to the procedure shown in Figure 6. In the actual experiment, the turbidity of the flushing water was measured according to the progress of flushing, and flushing was completed when it was confirmed that the turbidity fell below 20.

[0089] The cleaning device 1 is configured by mounting a single-structure filter 12 or a composite-structure filter 14 on a screen 9 of a strainer 6 provided near each heat source device 2 (air-cooled heat pump chiller) according to each process.

[0090] The specific procedure for the actual experiment is as follows: after installing the cleaning device 1, water is supplied to the piping system P through the water supply pipe 16 to fill it with water and remove the air; after confirming that the piping system P is full of water, as the first step, water is circulated through the piping system P with the single-piece filter 12 attached to the screen 9.

[0091] The water circulation in the first step is performed continuously for 2 to 4 hours, with a target of circulating 20 to 40 times through the piping system P, and is judged based on whether the turbidity has converged for the first time. Immediately after the water circulation starts, flushing water (initial water) is sampled from the drain pipe 17 and the turbidity is measured, and flushing water (first intermediate water) is also sampled after the end of the first step and the turbidity is measured.

[0092] After the first step is completed, the valves before and after the strainer 6 are closed, the screen 9 is removed and cleaned, and then replaced with the composite structure filter 14. As the second step, the water is circulated again through the piping system P.

[0093] The water circulation in the second step is similar to that in the first step, and is performed continuously for 2 to 4 hours, aiming at circulating the water through the piping system P 20 to 40 times, and is judged based on whether the turbidity has converged to the second level. After the second step is completed, the flushing water (second intermediate water) is sampled and the turbidity is measured.

[0094] Next, in the third step, the valves of the water supply pipe 16 and the water drain pipe 17 are opened, and water is supplied to and drained from the piping system P at the same time.

[0095] Flushing water is sampled and its turbidity measured as appropriate. When it is confirmed that the turbidity is below 20 degrees, the valves of the water supply pipe 16 and the water drain pipe 17 are switched to the closed position to stop the water supply and drainage.

[0096] Finally, the valves before and after the strainer 6 are closed, the screen 9 is removed, the composite structure filter 14 is collected, the screen 9 is washed, and then returned to the strainer 6 to complete the flushing.

[0097] A comparison of the operation time between conventional flushing (the method shown in Fig. 20) and the cleaning method according to the present invention is shown in Fig. 16 and Fig. 17, and a comparison of the amount of drainage is shown in Fig. 18. In comparing the operation time, the operation time was calculated assuming that the time required for draining water is equal to the time required for water supply in the conventional flushing.

[0098] 16 and 17, the cleaning method according to the present invention does not require water exchange (filling with water and replacing the water by draining it), so the time required for draining and supplying water for water exchange can be significantly reduced. The effect of reducing work time by the cleaning method according to the present invention was a 28% reduction compared to one water exchange, a 55% reduction compared to two water exchanges, and a 68% reduction compared to three water exchanges in the cold / hot water system. Also, in the reheat hot water system, the reduction was a 34% reduction compared to one water exchange, a 54% reduction compared to two water exchanges, and a 68% reduction compared to three water exchanges.

[0099] 18, in terms of the amount of drainage, in conventional flushing, the amount of drainage is equal to the amount of water held in the piping system for each water exchange, whereas in the cleaning method according to the present invention, the work is completed with a drainage amount less than the amount of water held in the piping system P, so that the effect of reducing the amount of drainage by the cleaning method according to the present invention is 49% reduction compared to one water exchange, 74% reduction compared to two water exchanges, and 83% reduction compared to three water exchanges in the cold / hot water system. Also, in the reheat hot water system, the reduction is 31% reduction compared to one water exchange, 65% reduction compared to two water exchanges, and 77% reduction compared to three water exchanges.

[0100] As a result, the cleaning method according to the present invention can reduce the work time and the amount of wastewater required for flushing compared to conventional flushing.

[0101] Next, the transition of the turbidity of the flushing water is shown in Figure 19, and the analysis results of the flushing water are shown in Table 1. The analysis items of the flushing water were determined based on the water quality standards (JRA GL-02-1994) set forth by the Japan Refrigeration and Air Conditioning Industry Association. [Table 1]

[0102] As shown in Fig. 19, the turbidity decreases as the flushing operation progresses, and the turbidity of the water at completion is reduced to 10 or less. In addition, the water quality also meets the standard values ​​for all items, confirming that there are no problems with the cleaning device 1 and cleaning method according to the present invention.

[0103] In general, the amount of residue in the pipe at the start of flushing increases or decreases depending on the construction method and management method of the pipe, and the flushing time and the amount of drainage increase or decrease. In the case of the site in this example, the pipe processing work at the site was only threading, and the pipe was carefully wiped after threading to prevent cutting chips and cutting oil from getting into the inside of the pipe, and the welding work was performed at a factory, so the amount of foreign matter generated at the site was relatively small. However, if welding work occurs at the site or if the piping material stored at the site is not properly protected, the amount of foreign matter mixed into the pipe increases, so the flushing time is thought to increase. In addition, since cutting oil is difficult to remove with a filter, etc., if a large amount of cutting oil is mixed in, the amount of fresh water and the amount of drainage required for the third step are thought to increase. In actually applying the present invention, by adopting a protection method and work method that prevent foreign matter generated at the site from getting into the inside of the pipe, it is possible to improve the accuracy of the effect of the present invention, such as shortening the flushing time and reducing the amount of fresh water and drainage. [Explanation of symbols]

[0104] 1...Cleaning device, 2...Heat source equipment, 3...Air conditioning equipment, 4...Pipe for cooling / heating medium, 5...Gate valve, 6...Strainer, 7...Main body, 8...Capturing part, 9...Screen, 10...Cover, 11...Coarse filter sheet, 12...Single structure filter, 13...Dense filter sheet, 14...Composite structure filter, 15...Cylindrical spacer, 16...Water supply pipe, 17...Drain pipe, 20, 21...Water tank, 22, 23...Water supply pipe, 24, 25...Water supply valve, 26, 27...Return pipe, 28, 29...Return valve, 30...Flow meter, 31...Pump, 32...Valve, 40...Bypass pipe, 41...Closing flange

Claims

1. A cleaning device used for flushing a piping system, comprising: The filter comprises a strainer connected to the piping system and having a built-in screen, a single-piece filter that is attached to the inside of the screen during flushing and is composed of only a relatively coarse filter, and a composite filter that is composed of a combination of a relatively coarse filter and a relatively fine filter, A piping system cleaning device characterized in that it is switchable between a state in which the single-structure filter is attached inside the screen and flushing is performed, and a state in which the composite-structure filter is attached inside the screen and flushing is performed.

2. 2. The piping system cleaning device according to claim 1, wherein the strainer is a Y-strainer, a T-strainer or a straight strainer having a cylindrical screen built therein.

3. 2. The piping system cleaning device according to claim 1, wherein said single-piece filter is formed by rolling a filter sheet into a roll from one end.

4. 2. The piping system cleaning device according to claim 1, wherein the composite structure filter is constructed by winding an outer filter made of a relatively fine-mesh filter sheet around the outer circumference of an inner filter made of a relatively coarse-mesh filter sheet rolled into a roll from one end.

5. 2. The piping system cleaning device according to claim 1, wherein the single-structure filter and the composite-structure filter are arranged so as to fill the inside of the screen with each filter attached inside the screen.

6. 2. The cleaning device according to claim 1, wherein a cylindrical spacer having both ends open and a number of through holes formed on its circumferential surface is disposed in the center of at least one of the single-structure filter and the composite-structure filter, thereby reducing pressure loss.

7. A cleaning method used for flushing a piping system, comprising the steps of: A strainer having a built-in screen is connected to the piping system, a first step of circulating a fluid through the piping system in a state where a unitary filter constituted only of a relatively coarse filter is installed inside the screen; a second step of replacing the filter installed inside the screen with a composite structure filter composed of a combination of a relatively coarse filter and a relatively fine filter, and circulating a fluid through the piping system.

8. 8. The method for cleaning a piping system according to claim 7, further comprising the step of: if the cleanliness does not satisfy the target value at the stage of completing the second step, supplying water from a water supply pipe connected to the piping system and draining the water from a water drain pipe connected to the piping system, and exchanging the flushing water until the target cleanliness is achieved, said third step being carried out.

9. 8. The method for cleaning a piping system according to claim 7, wherein the water circulation in the first and second steps is carried out so that the fluid circulates through the piping system 20 to 40 times, respectively.

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