JP2021012048A - Cleaning method cleaning device - Google Patents

Abstract

To provide a cleaning method that enables a smaller amount of washing water to remove scale and contaminants from piping without dividing the piping.SOLUTION: The present cleaning method is the cleaning method for cleaning the inside of piping of a nuclear power plant facility. This method is configured to: supply washing water to a supply line 6 connected to piping 1; halt a supply to the supply line 6 of the washing water; inject compressed air inside the supply line 6 by a compressor 4; plunge the washing water inside the supply line 6 to the piping 1; and keep on injecting the compressed air inside the piping 1 through the supply line 6 by the compressor 4 until the washing water plunged inside the piping 1 is discharged from the piping 1.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cleaning method and a cleaning device using cleaning water and compressed air, and particularly removes scales and contaminants generated and accumulated on the inner surface of a pipe which is a cleaning target during operation of a nuclear plant facility, and removes the inner surface of the pipe. The present invention relates to a cleaning method and a cleaning device for cleaning the cleaning water, removing scales and impurities contained in the cleaning water, and reusing the purified cleaning water for cleaning the pipes.

Conventionally, there are the following cleaning methods as a method for removing scales and impurities generated and accumulated on the inner surface of piping of nuclear power plant equipment.
(1) Flushing cleaning with water A surging treatment method in which water is continuously injected into a pipe at a constant flow rate using a pump, and then the injection of water is stopped to remove scale generated and accumulated on the inner surface of the pipe.
(2) Chemical cleaning using chemicals A chemical treatment method in which a cleaning agent containing hydrochloric acid as a main component is repeatedly injected and discharged into a pipe, and the scale generated and accumulated on the inner surface of the pipe is dissolved or peeled off by the cleaning agent.

Japanese Unexamined Patent Publication No. 2012-55845 Japanese Unexamined Patent Publication No. 60-67896

According to the cleaning method (1), the cleaning effect can be obtained by the flow of water discharged from the pump. However, when water is injected into a pipe at a constant flow velocity, a pressure loss occurs depending on conditions such as the inner diameter and length of the pipe and the flow velocity in the pipe. Therefore, there are restrictions on the inner diameter and length of the pipe that can provide a sufficient cleaning effect on the pipe. On the other hand, if a pump having a large capacity and lift is selected in consideration of pressure loss, the pressure of water may exceed the limit pressure of the design specifications of the pipe and the pipe may be damaged. Further, as the pump equipment becomes large, it becomes difficult to handle the pump on site.

According to the cleaning method (2), the cleaning effect can be obtained by dissolving or peeling the scale with a cleaning agent. However, the use of a cleaning agent causes secondary waste liquid. In addition, waste liquid treatment according to the disposal standard is indispensable, and the use of chemicals for waste liquid treatment and additional work time for waste liquid treatment are required. In addition, the use of protective equipment required to handle chemicals limits the working environment. Since a muddy scale that cannot be completely dissolved by the cleaning agent is also generated on the inner surface of the pipe, the same problem as that of the cleaning method (1) may occur.

In either of the above cleaning methods (1) and (2), the constraint caused by the pressure loss generated when the fluid is sent into the pipe has a great influence, and the range in which a sufficient cleaning effect can be obtained for the pipe is limited. Will be done. Therefore, in order to obtain a sufficient cleaning effect, the pipe is cut and divided into a plurality of sections (for example, a 1,000 m pipe is divided into four parts) for cleaning. However, it is not an efficient cleaning method because the work and preparation and cleaning schedules associated with the divided cleaning increase.

In both of the above cleaning methods (1) and (2), since the fluid is continuously injected into the pipe for cleaning, the amount of water or cleaning agent used at the time of cleaning is the total internal volume of the pipe. About 5 times as much as is required. Further, in the cleaning method (2), since it is necessary to wash the inside of the pipe with water to remove the cleaning chemical, it is necessary to use an amount of water about 5 times the total internal volume of the pipe.

Therefore, an object of the present invention is to provide a cleaning method and a cleaning device capable of removing scales and impurities from the pipe with a smaller amount of cleaning water without dividing the pipe.

In one aspect, it is a cleaning method for cleaning the inner surface of a pipe of a nuclear plant facility, in which cleaning water is supplied to a supply line connected to the pipe and the supply of the cleaning water to the supply line is stopped. , Compressed air is injected into the supply line, the cleaning water in the supply line is pushed into the pipe, and the compressed air is discharged until the cleaning water pushed into the pipe is discharged from the pipe. A cleaning method is provided that continues to inject into the pipe through the supply line.

In one aspect, the amount of the wash water in the pipe that is swept away by the compressed air is 1% to 51% of the total internal volume of the pipe.
In one aspect, the flow velocity of the washing water in the supply line swept away by the compressed air is 1.5 m / s or more.
In one aspect, the cleaning method further comprises removing sewage from the piping before supplying the cleaning water into the supply line.
In one aspect, the cleaning method further comprises passing the cleaning water discharged from the pipe through a plurality of filters having a filtration accuracy of 1 μm to 15 μm.

In one aspect, the wash water that has passed through the plurality of filters is reused for cleaning the pipe or other pipes.
In one aspect, the step of supplying the wash water into the supply line, the step of stopping the supply of the wash water, and the compression until the turbidity of the wash water discharged from the pipe drops below the reference value. The step of pushing the washing water in the supply line with air into the pipe and the step of continuing to inject the compressed air into the pipe until the washing water pushed into the pipe is discharged from the pipe are repeated. ..

In one aspect, it is a cleaning device for cleaning the inner surface of the piping of the nuclear plant equipment, and is attached to the cleaning water storage tank for storing the cleaning water, a supply line extending from the cleaning water storage tank to the piping, and the supply line. A water supply pump for supplying the washing water in the washing water storage tank to the supply line and a compressor connected to the supply line are provided, and the compressor is provided with compressed air after the operation of the water supply pump is stopped. Is injected into the supply line, the cleaning water in the supply line is pushed into the pipe, and the compressed air is supplied until the cleaning water pushed into the pipe is discharged from the pipe. A cleaning device is provided that operates to continue injecting into the pipe through the line.

In one aspect, the cleaning device further comprises a water flow meter attached to the supply line.
In one aspect, the cleaning device includes a drainage receiving tank for collecting the washing water discharged from the pipe and the scale removed from the pipe, a wastewater septic tank, and a drainage transfer line extending from the drainage receiving tank to the wastewater septic tank. A first filter attached to the wastewater transfer line, a purification circulation line connected to the wastewater septic tank, and a second filter attached to the purification circulation line are further provided.

According to the present invention, since the scale and impurities accumulated on the inner surface of the pipe can be peeled off and removed without cutting and dividing the pipe up to a length of 1,000 m, the work load can be reduced and the operation stop period of the pipe can be shortened. Is possible.

By supplying the wash water into the supply line (and the pipe) and then continuously injecting compressed air into the pipe through the supply line, the previously supplied wash water is moved at high speed in the pipe. The high-speed flow of wash water makes it possible to peel off scales and impurities from the inner surface of the pipe. Further, since the cleaning water in the pipe is flushed with compressed air having a small friction loss, cleaning with a small load on the pipe can be performed.

In the conventional flushing cleaning method, the amount of cleaning water used for cleaning is about 5 times the total internal volume of the pipe. Further, in the conventional chemical cleaning method, water washing for removing the cleaning agent in the pipe is required, so that water of about 10 times the total internal volume of the pipe is required. Further, when the divided cleaning is performed, the amount of washing water used for the number of times of the divided cleaning is required. In the present invention, by using a combination of water (cleaning water) and compressed air, cleaning can be performed with an amount of cleaning water that is about three times the total internal volume of the pipe that is the object to be cleaned. Therefore, according to the present invention, the amount of wash water used can be reduced, the scale of the facility for storing the wash water can be reduced, and the work area can be reduced.

The scale, impurities, and washing water discharged from the piping, which is the object to be washed, are received by the drainage receiving tank. Solid scales and contaminants can settle and be recovered in the drainage tank. In addition, fine scales and impurities that cannot be collected in the wastewater receiving tank are removed by the first filter (filtration accuracy 10 μm to 15 μm), and the washing water that has passed through the first filter is guided into the wastewater septic tank. Further, by circulating the washing water between the second filter (filtration accuracy 1 μm to 3 μm) and the wastewater septic tank, fine scales and impurities contained in the washing water are removed by the second filter.

In this way, by removing fine scales and impurities with two filters having different filtration accuracy, it is possible to purify the cleaning water and reuse the cleaning water for cleaning the pipes. Since the filter adsorbs scale and impurities (particles), it is preferable that the filter has a high filtration capacity, but if only a high-capacity filter is used, the frequency of discarding the filter increases. Therefore, by using a plurality of filters having different filtration capacities as described above, it is possible to reduce the waste of the filters. Further, since no chemical is used in the present invention, scales and impurities (particles) in the washing water are not ionized, so that they can be easily adsorbed on the filter.

It is a schematic diagram which shows one Embodiment of the cleaning apparatus which concerns on this invention. It is a schematic diagram which shows the other embodiment of the cleaning apparatus which concerns on this invention. It is a flowchart explaining the cleaning method of cleaning the inner surface of a pipe using the said cleaning apparatus.

Hereinafter, the cleaning method and the embodiment of the cleaning device according to the present invention will be described with reference to the accompanying drawings.
One embodiment of the cleaning device of the present invention is configured as shown in FIG. In FIG. 1, reference numeral 1 is a pipe to be cleaned. The components represented by reference numerals 2 to 8 are configurations for supplying water (washing water) and compressed air into the pipe 1. The components represented by reference numerals 12 to 23 are configurations for receiving the washing water discharged from the pipe 1 and purifying the washing water. Further, the component represented by reference numeral 24 is a configuration for transferring purified wash water. The pipe 1 to be cleaned is a pipe of a nuclear power plant facility, for example, a resin pipe for transferring groundwater. The inner diameter of the pipe 1 is in the range of 25 mm to 250 mm, and the length of the pipe 1 is in the range of 10 m to 1000 m.

[water supply]
The washing water used for cleaning the pipe 1 is stored in the washing water storage tank 2. The washing water storage tank 2 is connected to one open end of the pipe 1 by a supply line 6. The supply line 6 extends from the washing water storage tank 2 to the pipe 1. The water supply pump 3 is provided on the supply line 6. In the present embodiment, first, the washing water stored in the washing water storage tank 2 is supplied to the supply line 6 by the water supply pump 3. At this time, a part of the washing water may flow through the supply line 6 and flow into the pipe 1. The amount of cleaning water used for one cleaning of the pipe 1 is 1% or more of the total internal volume of the pipe 1. The amount of this wash water can be set arbitrarily. The water flow meter 7 is attached to the supply line 6. The water flow meter 7 is configured to measure the flow rate of the washing water injected into the pipe 1 through the supply line 6.

[Continuous air supply]
A blower line 8 is connected to the supply line 6. More specifically, one end of the blower line 8 is connected to the supply line 6 at a position between the pipe 1 and the water supply pump 3, and the other end of the blower line 8 is connected to the compressor 4. The compressor 4 is connected to the supply line 6 through the blower line 8 and further communicates with the pipe 1 through the supply line 6. The air flow meter 5 is attached to the ventilation line 8. The air flow meter 5 is configured to measure the flow rate of compressed air sent from the compressor 4 to the supply line 6.

After the washing water is supplied to the supply line 6 (and the pipe 1) by the water supply pump 3, the operation of the water supply pump 3 is stopped. Next, the compressor 4 is operated to continuously send compressed air to the supply line 6 via the blower line 8. The wash water existing in the supply line 6 is pushed into the pipe 1 by the compressed air. At this time, the flow rate of the washing water flowing through the supply line 6 is measured by the water flow meter 7 installed in the supply line 6. The air flow of the compressed air by the compressor 4 is performed so that the flow velocity of the washing water flowing through the supply line 6 is maintained at 1.5 m / s or more, preferably 2.0 m / s or more. The flow velocity [m / s] can be calculated from the flow rate [m ³ / s] measured by the water flow meter 7 and the cross-sectional area [m ² ] of the supply line 6. The flow velocity of the washing water flowing through the supply line 6 corresponds to the flow velocity of the washing water flowing into the pipe 1.

The operation of the compressor 4, that is, the injection of compressed air, continues even after the wash water in the supply line 6 is pushed into the pipe 1. Therefore, the washing water is washed away in the pipe 1 by the compressed air. During continuous air supply of compressed air, the washing water existing in the pipe 1 moves at high speed as a water mass. This high-speed water mass can peel off and remove scale and impurities adhering to and accumulating on the inner surface of the pipe 1. Further, on the inner surface of the pipe 1, a turbulent flow in a water mass state in which the liquid phase and the gas phase are mixed is formed, and a strong stirring force is generated at the place where the mixed water mass passes, and scale and impurities are removed. A cleaning effect for removing peeling can also be obtained. In this way, the pipe 1 can be cleaned with two types of cleaning actions: high-speed flow and strong stirring force. The compressor 4 continues to inject compressed air into the pipe 1 through the supply line 6 until the washing water pushed into the pipe 1 is discharged from the pipe 1.

[Drainage]
The other end of the pipe 1 is connected to the drainage line 13. The drainage line 13 is connected to the drainage receiving tank 15. The washing water discharged from the pipe 1 is received in the drainage receiving tank 15 through the drainage line 13. The flow rate of the washing water flowing through the drainage line 13 is measured by a water flow meter 12 installed in the drainage line 13. The flow velocity [m / s] of the washing water flowing through the drainage line 13 can be calculated from the flow rate [m ³ / s] measured by the water flow meter 12 and the cross-sectional area [m ² ] of the drainage line 13.

The flow velocity of the washing water flowing through the drain line 13 corresponds to the flow velocity of the washing water flowing out from the pipe 1. In the present embodiment, the flow velocity of the washing water flowing through the drainage line 13 (that is, the flow velocity of the washing water flowing out from the pipe 1) is 1.5 m / s or more, preferably 2.0 m / s or more. The wash water flowing out of the pipe 1 is collected in the drainage receiving tank 15 together with the scale and impurities. A part of the washing water flowing through the drainage line 13 is guided to the sampling line 14, and the washing water is collected. The sampling line 14 is connected to the drainage line 13.

[Washing end judgment]
The water supply, continuous ventilation, and drainage described above are repeated until the inner surface of the pipe 1 is thoroughly cleaned. Judgment of the completion of cleaning of the pipe 1 is that scale and impurities are hardly visually recognized in the cleaning water collected from the sampling line 14, and / or the turbidity of the cleaning water is a predetermined reference value (for example, 20). Degree) It is done based on the decrease below. The reference value of turbidity is set to an arbitrary value according to the scale adhesion amount of the pipe 1 which is the object to be cleaned, but the turbidity of the cleaning water is lowered to 50 degrees or less, preferably 30 degrees or less, more preferably 20 degrees or less. In many cases, sufficient cleaning can be achieved by letting it do.

Large solid scales and contaminants associated with the wash water settle in the drainage tank 15 and deposit on the bottom of the drainage tank 15. The scale of solid matter and impurities deposited on the bottom of the drainage receiving tank 15 can be easily collected all at once. The washing water stored in the drainage receiving tank 15 is discharged to the drainage septic tank 19 by the drainage transfer pump 16 through the drainage transfer line 17 and the first filter 18 (filtration accuracy 10 μm to 15 μm). One end of the drainage transfer line 17 is connected to the drainage receiving tank 15, and the other end of the drainage transfer line 17 communicates with the wastewater septic tank 19. The drainage transfer pump 16 and the first filter 18 are installed in the drainage transfer line 17.

Most of the fine scales and impurities having a slow sedimentation rate are adsorbed and removed by the first filter 18 attached to the wastewater transfer line 17. The washing water that has passed through the first filter 18 flows into the wastewater septic tank 19 and is stored in the wastewater septic tank 19. A purification circulation line 20 is connected to the wastewater septic tank 19. Both ends of the purification circulation line 20 are connected to the wastewater septic tank 19, and the circulation pump 22 and the second filter 23 (filtration accuracy 1 μm to 3 μm) are installed in the purification circulation line 20. The second filter 23 has finer filtration accuracy than the first filter 18. When the circulation pump 22 is operated, the washing water circulates between the wastewater septic tank 19 and the second filter 23. Fine scales and impurities not removed by the first filter 18 are removed by the second filter 23. In this way, as the washing water circulates between the wastewater septic tank 19 and the second filter 23, the washing water is purified.

By removing the scale and impurities by the drainage receiving tank 15 and the filters 18 and 23, the cleaning water can be reused for cleaning the pipe 1 or another pipe. Therefore, since recycled water can be used even when cleaning a plurality of objects to be cleaned, the total amount of water used in the nuclear plant equipment can be reduced, the load on the water treatment equipment for final treatment of water can be reduced, and the time can be shortened. It is possible to treat water with water, which in turn leads to a reduction in the volume of waste.

The purified wash water is transferred from the wastewater septic tank 19 to the wash water storage tank 2 and reused for cleaning the inside of the pipe 1 or another pipe. The means for transferring the wash water from the wastewater septic tank 19 to the wash water storage tank 2 is not particularly limited. In the embodiment shown in FIG. 1, the purified wash water is temporarily transferred from the wastewater septic tank 19 to the tank trailer 24, and is transported to the wash water storage tank 2 by the tank trailer 24. In the embodiment shown in FIG. 2, the purified washing water in the wastewater septic tank 19 is returned to the washing water storage tank 2 through the purified washing water return line 25. The wash water returned to the wash water storage tank 2 is supplied from the wash water storage tank 2 to the pipe 1 or another pipe as a cleaning target.

Next, a cleaning method for cleaning the inner surface of the pipe 1 using the cleaning device will be described with reference to the flowchart shown in FIG.
In step 1, first, the sewage existing inside the pipe 1 is removed from the pipe 1. The purpose of removing the sewage from the pipe 1 is to supply an accurate amount of wash water to the supply line 6 in the next step 2. In the present embodiment, the compressor 4 is operated to send compressed air into the pipe 1 through the supply line 6 to remove sewage from the pipe 1. In one embodiment, the drain (not shown) connected to the pipe 1 may be opened to remove the sewage from the pipe 1.

In step 2, the water supply pump 3 is operated to supply the washing water in the washing water storage tank 2 into the supply line 6. At this time, a part of the washing water may be supplied to the pipe 1.
In step 3, the operation of the water supply pump 3 is stopped, and the supply of the washing water to the supply line 6 is stopped.

In step 4, the compressor 4 is activated to start injecting compressed air into the supply line 6. The compressed air pushes the cleaning water existing in the supply line 6 into the pipe 1. At this time, the flow velocity of the washing water flowing through the supply line 6 is 1.5 m / s or more, preferably 2.0 m / s or more.
In step 5, the injection of compressed air into the pipe 1 is continued through the supply line 6 until the cleaning water pushed into the pipe 1 by the compressed air in step 4 is discharged from the pipe 1 (continuing the operation of the compressor 4). ). In other words, the cleaning water pushed into the pipe 1 by the compressed air is discharged from the pipe 1, and after the compressed air begins to flow out from the pipe 1, the injection of the compressed air into the pipe 1 is stopped (the operation of the compressor 4 is performed). Stop).
The steps from step 2 to step 5 are repeated a plurality of times until the turbidity of the washing water discharged from the pipe 1 becomes equal to or less than the reference value.

In step 6, the washing water collected in the drainage receiving tank 15 is passed through the first filter 18 and the second filter 23 to purify the washing water.
In step 7, the purified wash water is stored in the wastewater septic tank 19. The purified wash water in the wastewater septic tank 19 is returned to the wash water storage tank 2.
In step 8, the purified wash water is reused for cleaning pipe 1 or another pipe.

給水量(％)は、圧縮空気によって押し流される配管１内の洗浄水の量の、配管１の総内容量に対する割合である。供給側流速(m/s)は、供給ライン６を流れる洗浄水の流速、すなわち配管１に流入する洗浄水の流速である。排出側流速(m/s)は、排出ライン９を流れる洗浄水の流速、すなわち配管１から流出した洗浄水の流速である。 [Example 1]
Table 1 shows the measurement results of the flow velocity of the cleaning water with respect to the amount of the cleaning water supplied to the pipe 1 which is the object to be cleaned by using the cleaning device shown in FIG.

The water supply amount (%) is a ratio of the amount of washing water in the pipe 1 swept away by the compressed air to the total internal capacity of the pipe 1. The supply-side flow velocity (m / s) is the flow velocity of the washing water flowing through the supply line 6, that is, the flow velocity of the washing water flowing into the pipe 1. The discharge side flow velocity (m / s) is the flow velocity of the washing water flowing through the discharge line 9, that is, the flow velocity of the washing water flowing out from the pipe 1.

In the cleaning method according to the present invention, since the cleaning water in the pipe 1 is pushed out using compressed air, the flow velocity of the cleaning water can be increased without excessively increasing the pressure in the pipe 1. That is, since the resistance to the compressed air in the pipe 1 is small, the compressed air can flush the cleaning water in the pipe 1 at high speed without excessively increasing the pressure of the compressed air itself. From the viewpoint of increasing the flow rate of the washing water, the amount of water supplied (%) is preferably 1% to 51%. The experimental results shown in Table 1 show that the water supply amount (%) is preferably 1% to 39%, more preferably 1% to 22%. Considering the saving of washing water, the amount of water supplied (%) is preferably 1% to 15%.

[Comparative Example 1]
Table 2 shows the measurement results of the flow velocity of the cleaning water obtained by using compressed air instead of carbon dioxide in the cleaning method described in Patent Document 1 for the pipe 1. In this experiment, the cleaning method of Patent Document 1 was carried out using the cleaning apparatus shown in FIG. Although the flow velocity on the supply side and the drainage side both reached 1.5 m / s, they did not reach 2.0 m / s, and since a large amount of water was used, it was not practical.

本発明の洗浄方法は、化学洗浄法およびフラッシング洗浄法と比較すると、必要総工期で約６２％減少、全停止日数で約７６％減少であった。この実験結果から、本発明の洗浄方法は所要日数を削減できることがわかる。 Next, Tables 3 to 5 show the difference between the results of the conventional cleaning method and the cleaning method of the present invention.

Compared with the chemical cleaning method and the flushing cleaning method, the cleaning method of the present invention reduced the total required construction period by about 62% and the total number of stop days by about 76%. From this experimental result, it can be seen that the cleaning method of the present invention can reduce the required number of days.

本発明の洗浄方法は、化学洗浄法と比較すると配管１０００ｍあたりの使用水量で約７７％減少でき、フラッシング洗浄法と比較すると配管１０００ｍあたりの使用水量で５０％減少できた。この実験結果から、本発明の洗浄方法は使用水量を削減できることがわかる。

The cleaning method of the present invention was able to reduce the amount of water used per 1000 m of the pipe by about 77% as compared with the chemical cleaning method, and was able to reduce the amount of water used per 1000 m of the pipe by 50% as compared with the flushing cleaning method. From this experimental result, it can be seen that the cleaning method of the present invention can reduce the amount of water used.

As a conventional cleaning method for piping of nuclear plant equipment, as described in Patent Document 2, water (cleaning liquid) and air are alternately injected into the piping at arbitrary intervals to clean the piping. There is also. In this method, sludges are blown up by alternately generating liquid plugs and air columns in the pipe, and the sludges are transported at high speed for cleaning.

However, the major difference between the present invention and the method of Patent Document 2 is that in the present invention, only a predetermined amount of water (cleaning liquid) is flushed with compressed air, so that the amount of cleaning water used can be reduced, and piping. Since the amount of wash water existing in 1 is small, the flow velocity of the wash water can be increased. In addition, there is an advantage that the facilities of the washing water storage tank 2 and the drainage receiving tank 15 for storing the washing water do not become large. Further, when the washing water is reused, there is an advantage that the washing water can be purified in a short time. In addition, since the amount of wash water to be reused is small, there is an advantage that the devices and means for transfer are not excessive and complicated.

Further, in the cleaning method of Patent Document 2, it is assumed that the amount of cleaning liquid inevitably increases as the inner diameter of the pipe of the object to be cleaned increases, and it is essential to select a large pump capacity and lift specifications of the water supply equipment. become. On the other hand, in the present invention, only a predetermined amount of washing water needs to be supplied into the supply line 6 (and the pipe 1), so that the capacity and head required for the water supply pump 3 are the inner diameter of the pipe. Does not depend on.

Further, in the cleaning method of Patent Document 2, the longer the piping of the object to be cleaned, the more pressure loss occurs when the cleaning liquid is continuously injected, and the specifications of the pump capacity and lift of the water supply facility in consideration of the head loss. Selection is required. On the other hand, in the present invention, since the cleaning water is moved as a water mass by continuously supplying compressed air into the pipe, the pump specifications of the water supply facility are not restricted.

The effluent recycling method of Patent Document 2 is to send the lavage effluent to a hydrocyclone and separate the solid matter and the effluent effluent by a centrifugal separation method. In general, centrifugal separation type solid-liquid separation does not use a filter medium (filter) or the like, so it has the advantage of not generating waste, but it is presumed that solid fine particles (10 μm or less) cannot be completely separated. Therefore, when the cleaning liquid is reused, the cleanliness of the cleaning liquid may not be maintained. On the other hand, in the above embodiment of the present invention, since two filters having a filtration accuracy of 1 μm to 15 μm are used, solid fine particles of 10 μm or less can be removed, and the cleanliness of the wash water when the wash water is reused. Can be kept enough.

In the conventional technique, the cleaning range to the object to be cleaned is limited due to the pressure loss generated when the fluid in the pipe is passed, and it is necessary to cut and clean the pipe. Since the cleaning device uses compressed air, pressure loss is small and a high flow velocity can be achieved at a lower pressure. As a result, it is not necessary to cut the pipe and divide it into multiple pieces. Furthermore, it is possible to reduce the amount of cleaning water used, reduce the workload, reduce the scale of cleaning equipment, shorten the period of suspension of operation of the object to be cleaned, and shorten the entire construction period. From this, the cleaning method and the cleaning device of the present invention make a great contribution from the viewpoints of exposure dose, securing of water used, and reduction of waste volume in nuclear power plant equipment.

The above-described embodiment is described for the purpose of enabling a person having ordinary knowledge in the technical field to which the present invention belongs to carry out the present invention. Various modifications of the above embodiment can be naturally performed by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is construed in the broadest range according to the technical idea defined by the claims.

1 Piping (object to be cleaned)
2 Washing water storage tank 3 Water supply pump 4 Compressor 5 Air flow meter 6 Supply line 7 Water flow meter (supply side)
8 Blower line 12 Water flow meter (drainage side)
13 Drainage line 14 Sampling line 15 Drainage receiving tank 16 Drainage transfer pump 17 Drainage transfer line 18 1st filter 19 Drainage septic tank 20 Purification circulation line 22 Circulation pump 23 2nd filter 24 Tank trailer 25 Purification wash water return line

Claims (10)

A cleaning method for cleaning the inner surface of piping in nuclear plant equipment.
Wash water is supplied to the supply line connected to the pipe,
The supply of the washing water to the supply line is stopped,
Compressed air is injected into the supply line, and the cleaning water in the supply line is pushed into the pipe.
A cleaning method in which the compressed air is continuously injected into the pipe through the supply line until the cleaning water pushed into the pipe is discharged from the pipe. The cleaning method according to claim 1, wherein the amount of the cleaning water in the pipe that is swept away by the compressed air is 1% to 51% of the total internal volume of the pipe. The cleaning method according to claim 1 or 2, wherein the flow velocity of the cleaning water in the supply line swept away by the compressed air is 1.5 m / s or more. The cleaning method according to any one of claims 1 to 3, further comprising a step of removing sewage from the pipe before supplying the cleaning water into the supply line. The cleaning method according to any one of claims 1 to 4, further comprising a step of passing the cleaning water discharged from the pipe through a plurality of filters having a filtration accuracy of 1 μm to 15 μm. The cleaning method according to claim 5, wherein the cleaning water that has passed through the plurality of filters is reused for cleaning the pipe or other pipes. The step of supplying the washing water into the supply line, the step of stopping the supply of the washing water, and the step of supplying the washing water with compressed air until the turbidity of the washing water discharged from the pipe drops below the reference value. The step of pushing the washing water in the line into the pipe and the step of continuing to inject the compressed air into the pipe until the washing water pushed into the pipe is discharged from the pipe are repeated. The cleaning method according to any one of 6 to 6. A cleaning device for cleaning the inner surface of piping in nuclear plant equipment.
A wash water storage tank that stores wash water and
A supply line extending from the washing water storage tank to the pipe,
A water supply pump attached to the supply line and supplying the washing water in the washing water storage tank into the supply line.
Equipped with a compressor connected to the water supply
After the operation of the water supply pump is stopped, the compressor injects compressed air into the supply line, pushes the cleaning water in the supply line into the pipe, and further pushes the cleaning water into the pipe. A cleaning device that operates to continue injecting the compressed air into the pipe through the supply line until water is discharged from the pipe. The cleaning device according to claim 8, further comprising a water flow meter attached to the supply line. A drainage receiving tank that collects the washing water discharged from the pipe and the scale removed from the pipe.
Wastewater septic tank and
A wastewater transfer line extending from the wastewater receiving tank to the wastewater septic tank,
The first filter attached to the drainage transfer line and
A purification circulation line connected to the wastewater septic tank and
The cleaning device according to claim 8 or 9, further comprising a second filter attached to the purification circulation line.

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