KR20120084207A - Pressuer type filtering device and control method thereof - Google Patents

Abstract

PURPOSE: A pressurizing type filtering apparatus and a method for controlling the same are provided to save costs required for a backwashing mode by automating the backwashing mode based on the operation of a 4-way valve. CONSTITUTION: A pressurizing type filtering apparatus includes a filtering part, a 4-way valve(40), and a pressure measuring part. The filtering part filters feed water by passing stacked filtering media. The 4-way valve controls the flow of feed water supplied to the filtering part, filtered water from the filtering part, and washing water for washing the filtering part. The pressure measuring part measures the pressure of the feed water introduced into the filtering part through the 4-way valve and the pressure of the filtered water from the filtering part.

Description

Pressurized filtration device and its control method {PRESSUER TYPE FILTERING DEVICE AND CONTROL METHOD THEREOF}

The present invention relates to a filtration device, and more particularly, to a pressurized filtration device and a control method thereof capable of reducing maintenance costs while increasing raw water treatment capacity per unit area.

In general, a water purification facility for filtering and filtering raw water in a swimming pool or rainwater treatment facility is filtered through a sand filter after administering a coagulant such as a polymer to the raw water.

After passing through the sand filter, the raw water is sterilized and disinfected and then fed back to the swimming pool.

The above technical configuration is a background art for helping understanding of the present invention, and does not mean a conventional technology well known in the art.

Since the raw water injected with the polymer passes through the sand filter, the backwash cycle for cleaning the sand filter is accelerated, and a large cost is required to replace the contaminated sand.

In addition, since the installation space of the sand filter is large, the raw water treatment capacity per unit area is reduced, thereby reducing the space utilization. Therefore, there is a need to improve this.

The present invention has been made by the necessity as described above, and an object thereof is to provide a pressurized filtration device and a control method thereof capable of filtering raw water without adding a polymer.

In addition, an object of the present invention is to provide a pressurized filtration device and a control method thereof capable of reducing maintenance costs by simplifying the backwashing process for cleaning the filtration device.

Another object of the present invention is to provide a pressurized filtration device and a control method thereof, which can improve the efficiency of a device for filtering raw water to improve the treatment capacity of raw water per unit area.

The pressurized filtration device according to the present invention includes: a filtration unit for filtering raw water through a stacked filter medium, a four-way valve for controlling the flow of raw water supplied to the filtration unit, filtered water and filtration unit discharged from the filtration unit, and controlling the flow of washing water discharged And a pressure measuring unit for measuring the pressure of the raw water flowing through the four-way valve into the filtration unit and the pressure of the filtered water discharged from the filtration unit.

In addition, the filtration unit preferably includes an air discharge member for discharging the air inside the filtration unit to the outside.

In addition, the filter unit, the filter unit having a raw water supply port is formed on one side and the filter water discharge port is formed on the other side and the inclined water channel on the upper and lower surfaces, the filter unit having a filter net covering the upper surface of the filter plate and laminated on the upper side of the filter unit It is preferable to include a media storage stand in which the media is filled.

In addition, the four-way valve, the first connection pipe connecting the raw water supply port and the four-way valve, the second connection pipe connecting the filtered water outlet and the four-way valve, the supply pipe for supplying raw water to the four-way valve and the filtered water discharged through the four-way valve Or it is preferable that the discharge pipe to which the washing water is moved.

In addition, the four-way valve, the filtration mode in which the raw water supplied through the supply pipe is moved to the first connection pipe and the filtered water discharged through the second connection pipe is discharged to the discharge pipe and the second source pipe supplied through the supply pipe. It is preferable to have a backwashing mode in which the washing water discharged through the first connection pipe is discharged to the discharge pipe.

In addition, the discharge pipe is connected to the main discharge pipe for discharging the filtered water and the sub discharge pipe for discharging the washing water, it is preferable that the first valve member and the second valve member for opening and closing the flow path is provided in the main discharge pipe and the sub discharge pipe.

In addition, the present invention preferably further includes a pump unit installed in the supply pipe to force the movement of raw water and a vibration reducing member elastically supporting the pump unit.

In another aspect, the present invention, it is preferable to further include a mixing tank portion which is connected to the supply pipe and the supplement material of the medium is mixed and supplied.

In addition, the pressure measuring unit preferably includes a first measuring member for measuring the pressure of the raw water flowing into the filtration unit and a second measuring member for measuring the pressure of the filtered water discharged from the filtration unit.

The control method of the pressurized filtration device according to the present invention includes: a raw water supply step of supplying raw water along a supply pipe, a filtration step of filtering raw water passing through a four-way valve to a filtering part through a first connecting pipe, and a filtration part; Filtrate discharged from the second connection pipe in the filtered water discharge step is discharged through the discharge pipe, and the pressure of the raw water flowing into the filtration unit and the filtered water discharged from the filtration unit is measured, if the difference is greater than the set pressure backwash mode And the raw water passing through the four-way valve is supplied to the filtration unit through the second connecting pipe to wash the filter medium, and then the backwashing step discharged to the first connecting pipe and discharged to the first connecting pipe. Washing water discharge step to discharge through the pipe.

In the pressurized filtration device and the control method thereof according to the present invention, since the raw water is introduced into the filtration unit and filtered without introducing the polymer, the cost used for filtration of the raw water can be reduced.

In addition, the present invention, since the backwash mode for cleaning the filtration unit is automated by the operation of the four-way valve, the work time put into the backwash mode is reduced, the cost of replacing the filter medium for filtering the raw water is also reduced can reduce the maintenance cost .

In addition, in the present invention, since a plurality of media of the filtration unit is stacked to filter the raw water, the efficiency of the filtration unit for filtering the raw water can be improved to improve the treatment capacity of the raw water per unit area.

1 is a perspective view schematically showing a pressure filtration device according to an embodiment of the present invention.
Figure 2 is a perspective view schematically showing the rear of the pressure filtration device according to an embodiment of the present invention.
3 is a front view schematically showing a pressure filtration device according to an embodiment of the present invention.
Figure 4 is a front view schematically showing a pressure filtration device according to an embodiment of the present invention.
5 is a schematic exploded perspective view of a filter unit according to an exemplary embodiment of the present invention.
Figure 6 is a side cross-sectional view showing a state in which raw water is filtered through the filtration unit according to an embodiment of the present invention.
7 is a side cross-sectional view showing a state in which the filtration unit is cleaned according to an embodiment of the present invention.
8 is a perspective view schematically showing a fastening state of the filter unit according to an embodiment of the present invention.
9 is a block diagram showing a connection state of the pressure measuring unit according to an embodiment of the present invention.
10 is a flowchart illustrating a control method of the pressure filtration device according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of a pressure filtration device and a control method according to the present invention. For convenience of description, a pressurized filtration device for filtering raw water of a swimming pool and a control method thereof will be described as an example. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or convention of a user or an operator. Therefore, definitions of these terms should be made based on the contents throughout the specification.

1 is a perspective view schematically showing a pressure filtration device according to an embodiment of the present invention, Figure 2 is a perspective view schematically showing a rear of the pressure filtration device according to an embodiment of the present invention, Figure 3 is 4 is a front view schematically showing a pressure filtration device according to an embodiment of the present invention, Figure 4 is a front view schematically showing a pressure filtration device according to an embodiment of the present invention, Figure 5 is an embodiment of the present invention 6 is a perspective view schematically illustrating an exploded view of the filter unit, and FIG. 6 is a side cross-sectional view illustrating a state in which raw water is filtered through the filter unit according to an embodiment of the present invention, and FIG. 7 is a filter unit according to an embodiment of the present invention. Figure 8 is a side cross-sectional view showing a state of cleaning, Figure 8 is a perspective view schematically showing a fastening state of the filter unit according to an embodiment of the present invention, Figure 9 is a pressure according to an embodiment of the present invention It is a block diagram showing the connection state of a measurement part.

1 to 9, the pressure filtration device 1 according to an embodiment of the present invention, the filter unit 10 for filtering the raw water (3) through the stacked filter medium 33, Four-way valve 40 for washing the raw water (3) supplied to the filtration unit 10 and the filtration water (5) and the filtration unit 10 discharged from the filtration unit 10 and controls the flow of the washing water (7) discharged And a pressure measuring unit 60 measuring the pressure of the raw water 3 flowing through the four-way valve 40 into the filtration unit 10 and the pressure of the filtrate 5 discharged from the filtration unit 10. .

The pressurized filtration device (1) is provided with a plurality of pipes for guiding the flow of raw water (3), filtrate (5) and washing water (7), the four-way valve (40) connected to these pipes to change the flow of the fluid Is installed.

Four-way valve 40 according to an embodiment operates as a control signal of the control unit 66, the raw water (3) supplied to the filtration unit 10 and the filtered water (5) and filtration unit discharged from the filtration unit 10 (10) to wash and control the flow of the washing water (7) discharged.

To this end, the four-way valve 40 has a first connection pipe 50 connecting the raw water supply port 14 and the four-way valve 40, and a second connection connecting the filtrate water outlet 16 and the four-way valve 40. A pipe 51, a supply pipe 52 for supplying raw water 3 to the four-way valve 40, and a discharge pipe 53 for moving the filtrate 5 or the washing water 7 discharged through the four-way valve 40. ) Is connected.

The first connection pipe 50 is connected to the lower case 36 installed at the rear of the pressure filtration device 1, and the second connection pipe 51 is installed at the front of the pressure filtration device 1 at the lower case ( 36).

The four-way valve 40 is operated by the control signal of the control unit 66 to operate in the filtration mode or backwash mode to control the flow of the fluid.

When the four-way valve 40 is operated in the filtration mode, the raw water 3 supplied through the supply pipe 52 is moved to the first connection pipe 50 and discharged through the second connection pipe 51. 5) is discharged to the discharge pipe (53).

When the four-way valve 40 is operated in the backwash mode, the raw water 3 supplied through the supply pipe 52 is moved to the second connection pipe 51 and the washing water discharged through the first connection pipe 50 ( 7) is discharged to the discharge pipe (53).

The discharge pipe 53 is connected to the main discharge pipe 54 for discharging the filtered water 5 and the sub discharge pipe 56 for discharging the washing water 7, and the main discharge pipe 54 and the sub discharge pipe 56 have flow paths. The first valve member 55 and the second valve member 57 are opened and closed.

Filtration portion 10 for filtering the raw water (3) moved through the first connecting pipe 50, the raw water supply port 14 is formed on one side and the filtered water outlet 16 is formed on the other side and the upper and lower surfaces The filter part 20 and the filter part 20 which have the filter plate 12 which forms the gradient channel 18, and the filter net 22 which covers the upper surface of the filter plate 12, and are laminated | stacked on the upper side of the filter medium 20, 33) includes a filter medium 30 is filled.

One side of the filter plate 12 includes a raw water supply port 14 formed to penetrate up and down, and the other side of the filter plate 12 includes a filter water discharge port 16 to penetrate up and down.

The upper and lower surfaces of the filter plate 12 are provided with a plurality of inclined channels 18 in the longitudinal direction with a predetermined interval.

The filter unit 20 coupled to the upper side of the filter plate 12 is provided with a filter net 22 inside the molding frame 24 forming an edge.

The filter media storage unit 30 is hermetically coupled to the upper surface of the filter net 22, a plurality of compartments 32 are provided, the filter material 33 is filled in such a compartment 32, foreign matter contained in the raw water (3) Remove it.

When stacking the other filter plate 12 on the upper surface of the filter medium (30), the packing 34 is fitted to the rim to be sealed.

The media storage 30 has a predetermined height to form a compartment 32 in the form of a lattice therein, and is supported by the filter net 22 positioned below the filter medium 33 filled in the compartment 32. .

After the filter plate 12, the filter unit 20, the filter case 30 and the packing 34 to form a continuous stack, the upper case 35 and the lower case 36 are installed at the upper and lower ends. In addition, the fastening bar 37 and the fastening nut 38 fix the filtering part 10 including the upper case 35 and the lower case 36.

The first connection pipe 50 is connected to the lower case 36 in communication with the raw water supply port 14, and the second connection pipe 51 is connected to the lower case 36 in communication with the filtered water outlet 16. .

The raw water 3 supplied through the first connection pipe 50 is introduced into the filtration unit 10 through the raw water supply holes 14 of the respective filter plates 12 and formed on the bottom surface of the filter plate 12. When passing along the inclined water channel 18 while passing through the filter medium (30) located on the lower side of the filter plate 12, the filtration process is made while passing through the filter medium 33 filled in the filter medium (30).

The filtrate (5) passing through the filter medium (33) passes through the filter net 22 again is moved downward along the inclined water path (18) formed on the upper surface of the filter plate 12, the filtered water formed on the other side of the filter plate 12 It is drained to the outside through the second connecting pipe 51 via the outlet 16.

In this filtration process, while the raw water 3 passes through the filter medium 33, impurities and foreign matters are caught and moved by the filter medium 33. Since the filtered water 5 passing through the filter medium 33 has a small amount of the foreign matter or the like that is caught by the filtering net 22 when passing through the filtering net 22, the life of the filtering net 22 can be significantly extended. .

The filtration unit 10 according to an embodiment of the present invention allows the raw water 3 to be finely filtered by a separate filter medium 33 without depending on the filtration network 22.

The filter medium 33 according to an embodiment may selectively use sand, charcoal, or activated carbon, and various materials may be used in the technical concept of performing a filtration function.

On the other hand, the number of the media storage rack 30 stacked on the filter net 22 may be stacked one or two or more.

In the case where two or more media storage racks 30 are continuous, the height of the layer formed by the media filter 33 is increased, and thus, fine filtering may be performed, and the media 33 filled in each media storage rack 30 may be used. The filtering function can be performed by differently.

For example, sand is charged into the filter medium (30) located on the upper side and the charcoal is charged into the filter medium (33) on the filter medium (30) placed on the lower side, and the raw water (3) is sand and Filtration can be accomplished in various ways while sequentially passing through the charcoal.

When it is necessary to clean the filter medium 33 or the filtering net 22, the backwash mode for supplying the raw water 3 to the filtered water outlet 16 is operated.

In this backwash mode, when air is filled inside the filtration unit 10, since the movement of the raw water 3 is not smooth, the air discharge member 39 discharging the air inside the filtration unit 10 to the outside. ) Is installed in the upper case (35).

The air discharge member 39 may be automatically operated by the control signal of the controller 66 and may be manually operated by the operator's operation.

The air discharge member 39 is operated manually or automatically, and opens the shielding pipe to communicate the lower side and the outer side of the upper case 35, thereby discharging the air in the lower side of the upper case 35 to the outside.

The pressure of the raw water (3) flowing through the four-way valve 40 to the filtration unit 10 and the pressure of the filtered water (5) discharged from the filtration unit 10 is measured by the pressure measuring unit (60).

The pressure measuring unit 60 measures the pressure of the first measuring member 62 for measuring the pressure of the raw water 3 flowing into the filtration unit 10 and the filtered water 5 discharged from the filtration unit 10. And a second measuring member 64, and the values measured by the first measuring member 62 and the second measuring member 64 are transmitted to the controller 66.

The mixing tank part 70 in which the supplementary material of the filter medium 33 is mixed and supplied is connected to the supply pipe 52.

In the mixing tank 70, diatomaceous earth or activated carbon is mixed as a supplementary material of the filter medium 33, and when the backwashing mode is completed, the mixing tank valve provided in the connection pipe 74 in conjunction with the operation of the pump unit 90. The 72 is opened and the supplemental material of the filter medium 33 is supplied to the filter medium storage stand 30.

Since the supply pipe 52 is connected to the foreign matter removal tank 80 for collecting hair and the like, the raw water 3 passes along the supply pipe 52 in a state in which foreign matter such as hair is filtered while passing the foreign matter removal tank 80. The four-way valve 40 is moved in the direction.

A vibration reducing member 95 is installed on the supply pipe 52 to elastically support the pump unit 90 below the pump unit 90 for forcing the movement of the raw water 3.

Coil spring may be used as the vibration reducing member 95, and in addition, various kinds of elastic members may be used as the vibration reducing member 95 in the technical concept of supplying elastic force.

Hereinafter, with reference to the accompanying drawings will be described in detail the control method of the pressure filtration device 1 according to an embodiment of the present invention.

10 is a flowchart illustrating a control method of the pressure filtration device according to an embodiment of the present invention.

As shown in Figure 1 to 10, the control method of the pressurized filtration device 1 according to an embodiment of the present invention, has a raw water supply step of supplying the raw water (3) along the supply pipe (52). (S10)

The raw water 3 from which foreign substances such as hair are removed while passing through the foreign substance removal tank 80 is moved in the direction of the four-way valve 40 along the supply pipe 52.

Raw water 3 passing through the four-way valve 40 is moved to the filtration unit 10 through the first connecting pipe 50 has a filtration step is filtered (S20).

When the four-way valve 40 is operated in the filtration mode, the raw water 3 moved through the supply pipe 52 moves to the raw water supply port 14 of the filtration unit 10 along the first connecting pipe 50. do.

After the raw water 3 introduced into the raw water supply port 14 is removed with foreign matter while passing through the plurality of stacked media 33 and the filtering network 22, the outside of the filtration unit 10 through the filtered water outlet 16. Is discharged.

The filtered water 5 discharged from the filtration unit 10 to the second connection pipe 51 has a filtered water discharge step discharged through the discharge pipe 53. (S30)

The filtered water 5 discharged to the outside of the filtration unit 10 is moved to the four-way valve 40 through the second connection pipe 51, and moves along the discharge pipe 53 in the four-way valve 40.

Since the first valve member 55 installed in the main discharge pipe 54 is opened and the second valve member 57 provided in the sub discharge pipe 56 is closed, the filtered water 5 moved along the discharge pipe 53 is It is discharged to the outside through the main discharge pipe (54).

Measuring the pressure of the raw water (3) flowing into the filtration unit 10 and the filtered water (5) discharged from the filtration unit 10, if the difference is greater than the set pressure or more change the flow path for operating the four-way valve 40 in the backwash mode It has a step (S40).

Second measurement member 64 for measuring the measured value of the first measuring member 62 for measuring the raw water (3) flowing into the filtration unit 10 and the pressure of the filtered water (5) discharged from the filtration unit 10 Measurement value is transmitted to the control unit 66.

If the pressure difference between the pressure of the raw water (3) and the pressure of the filtrate (5) is greater than or equal to the set pressure, the control unit (66) determines that foreign matter is deposited above the set value inside the filtration unit (10) and needs cleaning. (40) Operate in roll backwash mode.

The raw water 3 passing through the four-way valve 40 is supplied to the filtration unit 10 through the second connecting pipe 51 to wash the filter medium 33 and then discharged to the first connecting pipe 50. (S50)

The raw water 3 moved along the supply pipe 52 is moved to the second connection pipe 51 through the four-way valve 40.

The raw water 3 flowing into the filtered water outlet 16 of the filtration unit 10 through the second connecting pipe 51 is moved upward along the inclined water channel 18 to filter the filter network 22 and the filter medium 33. After removing the foreign matter while passing in turn, it is moved to the four-way valve 40 through the first connection pipe 50 together with the foreign matter.

It has a washing water discharge step of discharging the washing water 7 discharged to the first connection pipe 50 through the discharge pipe 53. (S60)

The washing water 7 discharged to the outside of the filtration unit 10 is moved to the four-way valve 40 through the first connection pipe 50, and moves along the discharge pipe 53 at the four-way valve 40.

Since the first valve member 55 installed in the main discharge pipe 54 is closed and the second valve member 57 provided in the sub discharge pipe 56 is opened, the washing water 7 which is moved along the discharge pipe 53 is sub It is discharged outward through the discharge pipe 56.

According to the configuration as described above, the pressurized filtration device 1 and the control method according to one embodiment of the raw water (3) because the raw water (3) is introduced into the filtration unit 10 and filtered without the injection of the polymer, The cost used for filtration can be reduced.

In addition, since the backwash mode for cleaning the filtration unit 10 is automated by the operation of the four-way valve 40, the work time put into the backwash mode is reduced, and the replacement cost of the filter medium 33 filtering the raw water 3 is also reduced. It can reduce the maintenance cost.

In addition, since the plurality of filter mediums 33 of the filtration unit 10 are stacked to filter the raw water 3, the efficiency of the filtration unit 10 for filtering the raw water 3 is improved to increase the treatment capacity of the raw water 3 per unit area. Can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. I will understand.

In addition, the pressurized filtration device for filtering the raw water of the swimming pool and the control method has been described as an example, but this is merely illustrative, the pressurized filtration according to the present invention to other water treatment facilities for purifying raw water, such as rainwater treatment facilities other than the swimming pool. The device and its control method can be used.

Accordingly, the true scope of protection of the present invention should be defined by the claims.

1: pressurized filtration device 3: raw water
5: filtered water 7: washing water
10: filtration unit 12: filter plate
14: raw water supply port 16: filtered water outlet
18: inclined waterway 20: filter part
22: filter network 24: molding frame
30: Media rack 32: Compartment
33: Media 34: Packing
35: upper case 36: lower case
37: Fastening Bar 38: Fastening Nut
39: air exhaust member 40: four-way valve
50: first connection pipe 51: second connection pipe
52: supply pipe 53: discharge pipe
54: main discharge pipe 55: first valve member
56: sub discharge pipe 57: second valve member
60: pressure measuring unit 62: first measuring member
64: second measuring member 66: control unit
70: mixing tank part 72: mixing tank valve
74: connecting pipe 80: debris removal tank
90: pump portion 95: vibration reducing member

Claims (10)

Filtration unit for filtering the raw water through the laminated media;
Four-way valve for controlling the flow of the raw water supplied to the filtration unit, the filtration water discharged from the filtration unit and the filtration unit and the washing water discharged; And
And a pressure measuring unit for measuring the pressure of the raw water flowing through the four-way valve into the filtration unit and the pressure of the filtrate discharged from the filtration unit.
The method of claim 1, wherein the filtration unit,
Pressurized filtration device comprising an air discharge member for discharging the air in the inner side of the filtration unit to the outside.
The method of claim 1, wherein the filtration unit,
A filter plate configured to form a raw water supply port on one side and a filter water discharge port on the other side, and to form a sloped channel on the upper and lower surfaces thereof;
A filter unit having a filter net covering an upper surface of the filter plate; And
Stacked on the upper side of the filter portion, the pressure filtration device, characterized in that it comprises a filter medium filled with the filter material inside.
The method of claim 3, wherein the four-way valve,
A first connection pipe connecting the raw water supply port and the four-way valve, a second connection pipe connecting the filtrate water outlet and the four-way valve, a supply pipe for supplying raw water to the four-way valve, and discharged through the four-way valve. Pressurized filtration device, characterized in that the discharge pipe is connected to the filtered or washed water.
The method of claim 4, wherein the four-way valve,
A filtration mode in which raw water supplied through the supply pipe is moved to the first connection pipe, and the filtered water discharged through the second connection pipe is discharged to the discharge pipe; And
And a backwash mode in which raw water supplied through the supply pipe is moved to the second connection pipe, and the wash water discharged through the first connection pipe is discharged to the discharge pipe.
The method of claim 4, wherein
The discharge pipe is connected to the main discharge pipe for discharging the filtered water and the sub discharge pipe for discharging the washing water,
And a first valve member and a second valve member for opening and closing the flow path in the main discharge pipe and the sub discharge pipe.
The method of claim 4, wherein
A pump unit installed in the supply pipe to force movement of raw water; And
And a vibration reducing member for elastically supporting the pump unit.
The method of claim 4, wherein
Pressurized filtration device is connected to the supply pipe, characterized in that it further comprises a mixing tank portion for supplying the supplementary material of the filter medium is mixed.
According to claim 1, wherein the pressure measuring unit,
A first measuring member measuring a pressure of raw water flowing into the filtration unit; And
And a second measuring member for measuring the pressure of the filtered water discharged from the filtration unit.
Raw water supply step of supplying raw water along the supply pipe;
A filtration step in which raw water having passed through the four-way valve is moved to the filtration unit through the first connection pipe and filtered;
A filtered water discharge step of discharging the filtered water discharged from the filter unit to the second connection pipe through the discharge pipe;
A flow path changing step of operating the four-way valve in a backwash mode when the pressure between the raw water flowing into the filtering unit and the filtered water discharged from the filtering unit is different from the set pressure or more;
A backwashing step in which raw water passing through the four-way valve is supplied to the filtration unit through the second connecting pipe to wash the filter medium and then discharged to the first connecting pipe; And
And a washing water discharge step of discharging the washing water discharged through the first connection pipe through the discharge pipe.

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