WO2023176465A1

WO2023176465A1 - Filtration system

Info

Publication number: WO2023176465A1
Application number: PCT/JP2023/007721
Authority: WO
Inventors: 彰利中川; 直樹加藤
Original assignee: 株式会社明電舎
Priority date: 2022-03-17
Filing date: 2023-03-02
Publication date: 2023-09-21
Also published as: JP2023136529A; JP7380731B2

Abstract

The purpose of the present invention is to reduce the time and effort required for the maintenance and inspection work of filtration membrane units. This filtration system is equipped with a plurality of filtration membrane units (21), and a water collection pipe (90) provided with a main pipe (91) and a plurality of individual water collection channels that are aligned in the axial direction of the main pipe (91) and that communicate with the main pipe (91). This filtration system collects filtrate filtered by the filtration membrane (22) in each of the plurality of filtration membrane units (21), into the main pipe (91) of the water collection pipe (90) through a discharge channel and the individual water collection channels of the water collection pipe (90). This filtration system is equipped with a locking member (98) that locks the axial movement of the discharge channel in each of the plurality of filtration membrane units (21). Each of the plurality of filtration membrane units (21) is equipped with an O-ring comprising elastic material on the outer circumference of a discharge pipe that forms the discharge channel, and the discharge pipe is inserted into the individual water collection channels and locked against axial movement by the locking member (98).

Description

filtration system

The present invention relates to a filtration system.

Conventionally, a plurality of filtration membrane units each having a filtration membrane and a discharge port for discharging a filtrate obtained by the filtration membrane are provided, and the filtration membrane unit is arranged in the axial direction of the main pipe part and communicates with the main pipe part. BACKGROUND OF THE INVENTION Filtration systems are known that include a collection pipe with a plurality of individual collection channels.

For example, a membrane module unit as a filtration system described in Patent Document 1 includes a plurality of membrane modules as filtration membrane units and a water collection header as a water collection pipe. The water collection header includes a cylindrical portion serving as a main pipe portion, and a plurality of intermediate connecting portions (individual water collection channels) that communicate with the cylindrical portion from the radial direction of the cylindrical portion and are lined up in the axial direction of the cylindrical portion. Further, the membrane module includes a flat filtration membrane (hollow fiber membrane sheet) and a housing fixed to each of both ends of the filtration membrane in the longitudinal direction. A water intake port serving as a drainage port is arranged at one end of the filtration membrane in the short direction of the housing at both ends. The water intakes are individually connected by pipes to one of a plurality of intermediate connections in the water collection header. When a suction force is generated by the power of a pump, etc. on the filtration membrane of each membrane module through the cylindrical part of the water collection header and the intermediate connection part, the water in the sludge existing around the filtration membrane flows into the filtration membrane as filtrate. be sucked inside. The sucked filtrate is collected in the cylindrical portion of the water collection header via the water intake port of the housing of the membrane module, the pipe connected thereto, and the intermediate connection portion of the water collection header.

Patent No. 6319510

Patent Document 1 does not specifically describe how the plurality of intermediate connection parts of the water collection header and the pipes extending from the water intake ports of the plurality of membrane modules are connected. However, since a male thread is depicted on the outer peripheral surface of the cylindrical intermediate connection part in the drawing, it is thought that a union joint that can be threaded onto this male thread is used for connection. In a union joint, a female thread formed on the inner peripheral surface of a rotatable screw cup is screwed into a male thread on the outer peripheral surface of a pipe to be connected. In the membrane module unit described in Patent Document 1, when each of the plurality of membrane modules is individually connected to the intermediate connection part of the water collection header by a pipe, the screw cup of the union joint is rotated multiple times for each connection. You will be forced to take the trouble of tightening the screws. Furthermore, when removing individual membrane modules for maintenance and inspection, it is necessary to rotate the screw cup of the union joint in the opposite direction multiple times to loosen the screws. Furthermore, in order to operate the membrane module unit with the damaged membrane module removed, it is necessary to seal the intermediate connection part released by removal with a screw cap. You are forced to take the trouble of turning and tightening the screws several times.

The present invention has been made in view of the above background, and its purpose is to provide a filtration system that can reduce the effort required for maintenance and inspection of a filtration membrane unit such as a filtration system. .

One aspect of the present invention includes a plurality of filtration membrane units each including a filtration membrane and a discharge port for discharging the filtrate obtained by the filtration membrane, and the filtration membrane units are arranged in the axial direction of the main pipe part and the main pipe part, A water collection pipe is provided with a plurality of individual water collection channels communicating with the main pipe section, and the filtrate filtered by the filtration membrane in each of the plurality of filtration membrane units is passed through the individual water collection channels of the water collection pipe. A filtration system that collects water in the main pipe of the water collection pipe, comprising a locking member that locks the axial movement of the discharge pipe in each of the plurality of filtration membrane units. Each of them is provided with an O-ring made of an elastic material on the outer circumferential surface of the distal end of the discharge pipe, and when the discharge pipe is inserted into the individual water collection channel, the shaft of the discharge pipe is fixed by the locking member. It is characterized in that movement in the direction is locked.

According to the present invention, there is an excellent effect that the effort required for maintenance and inspection of the filtration membrane unit can be reduced.

1 is a diagram showing a schematic configuration of a water treatment facility using a filtration system according to an embodiment. It is a perspective view showing a filtration membrane unit of the same filtration system. FIG. 2 is a perspective view showing a water collection pipe installed in the filtration system. It is a sectional view showing the water collection pipe and a filtration membrane unit connected to its individual water collection channel. It is a figure which shows the same water collection pipe and the same filtration membrane unit from the axial direction of the main pipe part of a water collection pipe. It is a perspective view showing a sealing plug. It is a sectional view showing a sealing plug just before being inserted into an individual water collection channel of a water collection pipe, and a water collection pipe. It is a sectional view showing a sealing plug in the middle of being inserted into an individual water collection channel, and a water collection pipe. FIG. 3 is a sectional view showing a sealing plug inserted into an individual water collection channel and a water collection pipe. FIG. 3 is a cross-sectional view for explaining a preparation operation for pulling out the sealing plug. FIG. 11 is a sectional view showing the sealing plug and the water collection pipe immediately after the extraction preparation operation has been performed. It is a sectional view showing a sealing plug in the middle of being pulled out, and a water collection pipe. It is a perspective view showing filtration processing equipment.

Hereinafter, one embodiment of a liquid filtration device to which the present invention is applied will be described using each figure. In the embodiments, structures and elements other than the main parts of the present invention will be simplified or omitted in order to make the description easier to understand. Further, in each figure, the same elements are given the same reference numerals. Note that the shapes, dimensions, etc. of each element shown in each figure are shown schematically, and do not represent actual shapes, dimensions, etc.

FIG. 1 is a diagram showing a schematic configuration of a water treatment facility that uses a filtration system according to an embodiment. This water treatment facility includes a pre-treatment water tank 1, a filtered water tank 2, a treated water tank 3, a control device 4, a raw water pump 5, a first water level sensor 6, a raw water transfer pipe 7, a treated water transfer pipe 8, and a suction pump 9. , a second water level sensor 11, a third water level sensor 12, and the like. The water treatment facility also includes a blower 13, an air supply pipe 14, a pedestal 15, a filtration system 20, a bubble generator 30, and the like.

In the pre-processing water tank 1, pre-processing water (raw water) _W1 as a liquid is stored. A first water level sensor, such as an ultrasonic sensor, installed in the pre-treatment water tank 1 detects the water level (water surface height) of the pre-treatment water W ₁ in the pre-treatment water tank 1, and outputs the detection result to the water level. It is transmitted to the control device 4 as a signal. A raw water pump 5 installed in the pre-treatment water tank 1 sucks and discharges the pre-treatment water W ₁ in the pre-treatment water tank 1 and sends it to the filtration treatment water tank 2 through the raw water transfer pipe 7 . Although a submersible pump is illustrated as the raw water pump 5, a land pump may also be used.

The filtration treatment water tank 2 is a water tank made of reinforced concrete. A liquid filtration device 50 is installed in the filtration treatment water tank 2 . The liquid filtration device 50 includes a pedestal 15, a filtration system 20, and a bubble generator 30, and is entirely immersed in the pre-treatment water _W1 in the filtration treatment water tank 2. The blower 13 discharges air as a gas sucked through the suction port to the air supply pipe 14 through the discharge port. The air discharged into the air supply pipe 14 is supplied to the bubble generator 30 of the liquid filtration device 50. The third water level sensor 12 installed in the filtration treatment tank 2 detects the water level of the pre-treatment water _W1 in the filtration treatment tank 2, and transmits the detection result to the control device 4 as a water level signal.

The suction pump 9 sucks the untreated water W ₁ in the filtration treatment water tank 2 via the treated water transfer pipe 8 and a filtration membrane installed in the filtration system 20 and described below. The sucked untreated water W ₁ is filtered by a filter membrane to become treated water W ₂ , and then sent to the treated water tank 3 through the treated water transfer pipe 8 . The second water level sensor 11 set in the treated water tank 3 detects the water level of the treated water W2 in the treated water tank 3, and transmits the detection result to the control device 4 as a water level signal.

Note that instead of the suction pump 9, a pump that generates suction force using water head pressure may be used. The means of suction is not particularly limited.

When the water level in the treated water tank 3 has not reached the upper limit and predetermined operation execution conditions are met, the control device 4 operates the suction pump 9 and the blower 13 to remove the pre-treatment water _W1 . Execute the filtration process. However, even if the operation execution conditions are met, if the water level of the pre-treatment water W ₁ in the pre-treatment water tank 1 is below the lower limit, or if the water level of the pre-treatment water W ₁ in the filtration treatment water tank 2 is If it is below the lower limit, the control device 4 stops execution of the filtration process. Note that the role of the blower 13 will be described later.

FIG. 2 is a perspective view showing the filtration membrane unit 21. The filtration membrane unit 21 includes a flat filtration membrane 22, a socket tube 16, and a sealing holder 17. This filtration membrane unit 21 is held by four holding members 24 of a frame, which will be described later. In the liquid filtration device (50) according to the embodiment, a plate-shaped flat membrane is used as the filtration membrane 22, but the type of the filtration membrane 22 is not limited to a flat membrane, and may include other types such as a hollow fiber membrane. It may be a type. The material of the filtration membrane 22 may be an organic material such as PVC (polyvinyl chloride) or PVDF (polyvinylidene fluoride), and is composed of one or more types of alumina, cordierite, silicon carbide, and other metal oxides. It can also be made of ceramic. Further, the filtration membrane 22 may be a composite membrane made of an organic membrane and a ceramic membrane.

The filtration membrane 22 includes a plurality of hollow spaces 22a extending in the vertical direction. These hollow spaces 22a are arranged at predetermined intervals in the transverse direction of the filter membrane 22, and the upper end of the hollow spaces 22a is an opening facing "upward".

A socket pipe 16 is attached to one end of the filter membrane 22 in the longitudinal direction. This socket pipe 16 has an inner space that communicates with the hollow space 22a of the filtration membrane 22, and receives the treated water (W ₂ ) filtered by the filtration membrane 22 into the inner space. One end of the socket pipe 16 in the longitudinal direction is a discharge pipe 16a that protrudes from the end of the filtration membrane 22. This discharge pipe 16a has a discharge passage formed inside thereof, and is inserted into an individual water collection passage of a water collection pipe to be described later. Two O-rings 16b are attached to the outer circumferential surface of the discharge pipe 16a and are arranged in the axial direction of the insertion section. The O-ring 16b is made of an elastic material such as rubber or resin.

When the suction pump (9 in FIG. 1) operates, a suction force is generated on the surface of the filtration membrane 22, and the untreated water (W ₁ in FIG. It is sucked into the hollow 22a through the hole. At this time, the pre-treatment water W ₁ is filtered, and the pollutants in the pre-treatment water W ₁ remain on the surface of the filter membrane 22 . The treated water W ₂ sucked into the hollow 22 a moves in the longitudinal direction within the hollow 22 a, flows into the interior of the socket pipe 16 , and is then discharged from the discharge pipe 16 a of the socket pipe 16 .

In FIG. 1, a bubble generator 30 installed below the filtration system 20 emits bubbles toward the filtration system 20 above. The released bubbles float in the pre-treatment water _W1 , reach the filtration membrane 22, are divided into a plurality of parts by the filtration membrane 22, and then enter the region between the adjacent filtration membranes 22. The bubbles floating in this area violently shake the pre-treatment water _W1 near the surface of the filtration membrane 22, causing the pollutants adhering to the surface of the filtration membrane 22 to separate from the surface.

FIG. 3 is a perspective view showing the water collection pipe 90 installed in the filtration system (20). The water collection pipe 90 is made of a resin material such as polyethylene, polypropylene, polyvinyl chloride, or polyvinyl chloride by injection molding, and includes a cylindrical main pipe part 91 and a flat box-like water collection part 92. , and two rubber sheets 95. The water collection section 92 includes a plurality of individual water collection channels 93 that are arranged in the axis (L1) direction of the main pipe section 91 and communicate with the main pipe section 91 from a direction perpendicular to the axis L1. As shown in the figure, the individual water collection channels 93 are provided on both sides of the water collection section 92 with the center line L2 of the main pipe section 91 as a border.

FIG. 4 is a sectional view showing the water collection pipe 90 and the filtration membrane unit 21 connected to its individual water collection channel 93. As illustrated, the discharge pipe 16a of the filtration membrane unit 21 is inserted into the individual water collection channel 93 of the water collection pipe 90. Since the O-ring 16b is interposed between the outer circumferential surface of the inserted discharge pipe 16a and the inner circumferential surface of the individual water collection channel 93, airtightness between the two is ensured.

The rubber sheet 95 of the water collection pipe 90 is for preventing the filtration membrane 22 of the filtration membrane unit 21 from directly hitting the main pipe portion 91 of the water collection pipe 90 when the filtration membrane unit 21 is attached to the water collection pipe 90. It is.

FIG. 5 is a diagram showing the water collection pipe 90 and the filtration membrane unit 21 from the axial direction of the main pipe portion 91 of the water collection pipe 90. A locking member 98 is in contact with the socket pipe 16 of the filtration membrane unit 21 attached to the water collection pipe 90 from the side opposite to the water collection pipe 90 . A locking member 98 made of U-shaped steel is bolted to a frame to be described later, and extends in the axial direction of the main pipe portion 91 of the water collection pipe 90, and is attached to all the filtration membrane units 21 arranged in the coaxial direction. abuts on the socket pipe 16 of. Each of the plurality of filtration membrane units 21 locks the axial movement of the discharge pipe (16a) by a locking member 98 when the discharge pipe (16a) is inserted into the individual water collection channel (93) of the water collection pipe 90. will be stopped. The filtration membrane unit 21 locked in this manner prevents the discharge pipe (16a) that is not screwed to the individual water collection channel (93) from coming off from the individual water collection channel (93).

In this configuration, when connecting the drain pipes (16a) of each of the plurality of filtration membrane units 21 to the individual water collection channels (93) of the water collection pipe 90, the screw cup of the union joint is rotated and screwed. You are not forced to do laborious work. Simply insert the drain pipe (16a) into the individual water collection channel (93). Furthermore, when removing each filtration membrane unit 21 for maintenance and inspection, there is no need to perform the labor-intensive work of rotating the screw cup of the union joint in the opposite direction multiple times to loosen the screw. It is sufficient to simply pull out the drain pipe (16a) from the individual water collection channel (93). In addition, when operating the filtration system (20) with the damaged filtration membrane unit 21 removed, the individual water collection channels (93) released by the removal are sealed with a sealing plug to be described later.

FIG. 6 is a perspective view showing the sealing plug 100. The sealing plug 100 includes a hook portion 101, a flexible portion 102, a main body portion 103, and a handle 105 from the front end side to the rear end side. The hook part 101 has a slope part 101a that increases the radial dimension of the main body part 103 from the tip side to the rear end side in the axial direction of the cylindrical body part 103, and a slope part 101a that extends in the same radial direction at the rear end of the slope part 101a. The step portion 101b rapidly reduces the size of the step portion 101b. The flexible portion 102 has an elongated shape integrally formed with the hook portion 101 and the main body portion 103, and can be bent in the radial direction of the main body portion 103. The cylindrical main body portion 103 includes two O-rings 104 arranged in the axial direction on the outer peripheral surface of the distal end side. The O-ring 104 is made of an elastic material such as resin or rubber. The handle 105 protrudes rearward from the rear end surface of the main body 103 in the axial direction, and extends in the radial direction of the main body 103.

FIG. 7 is a sectional view showing the sealing plug 100 and the water collection pipe 90 immediately before being inserted into the individual water collection channel 93 of the water collection pipe 90. FIG. 8 is a sectional view showing the sealing plug 100 and the water collection pipe 90 that are being inserted into the individual water collection channel 93. FIG. 9 is a sectional view showing the sealing plug 100 inserted into the individual water collection channel 93 and the water collection pipe 90.

As shown in FIG. 7, the sealing plug 100 begins to be inserted into the individual water collection channel 93 with the hook portion 101 facing forward. As shown in FIG. 8, the sealing plug 100 that is being inserted slides the hook portion 101 on the tip side against the inner circumferential surface of the individual water collection channel 93. As the flexible portion 102 bends radially outward as a result of the sliding, the hook portion 101 can be inserted.

A hooked portion 91a on which the step portion 101b of the sealing plug 100 is hooked is arranged at the boundary between the individual water collection channel 93 of the water collection pipe 90 and the inner space of the main pipe portion 91. As shown in FIG. 9, the sealing plug 100 that has been completely inserted into the individual water collection channel 93 has the hook portion 101 on the tip side located in the communication area between the individual water collection channel 93 and the inner space of the main pipe portion 91. As a result, the sliding contact with the individual water collection channel 93 is released. At this time, the flexible portion 102, which had been bent until then, loses its bending, so that the stepped portion 101b of the hooking portion 101 is hooked on the hooked portion 91a, as shown in the figure. This catch prevents the sealing plug 100 from coming off the individual water collection channel 93. The O-ring 104 of the main body 103 is interposed between the outer circumferential surface of the main body 103 and the inner circumferential surface of the individual water collection channel 93 to ensure airtightness between the two.

FIG. 10 is a cross-sectional view for explaining the preparation operation for pulling out the sealing plug 100. FIG. 11 is a sectional view showing the sealing plug 100 and the water collection pipe 90 immediately after the extraction preparation operation has been performed. FIG. 12 is a sectional view showing the sealing plug 100 and the water collection pipe 90 in the middle of being pulled out.

When pulling out the sealing plug 100 from the individual water collection channel 93, a pulling out preparation operation is performed prior to pulling out. In this pull-out preparation operation, as shown in FIG. 10, the main body portion 103 is rotated approximately 90 degrees clockwise or counterclockwise while gripping the handle 105. Then, as shown in FIG. 11, the hook portion 101 of the sealing plug 100 rotates to a position where the stepped portion (101b) is not hooked on the hooked portion 91a. In this state, as shown in FIG. 12, by pulling the sealing plug 100, the sealing plug 100 can be pulled out from the individual water collection channel 93.

In this configuration, furthermore, when operating the filtration system with the damaged filtration membrane unit (21) removed from the water collection pipe 90, the individual water collection channel 93 released by the removal is sealed with the sealing plug 100. . When inserting or removing the sealing plug 100, there is no need to rotate the screw cap multiple times as described above.

Therefore, according to the filtration system (20) according to the embodiment, it is possible to reduce the effort required for maintenance and inspection of the filtration membrane unit (21).

FIG. 13 is a perspective view showing the filtration treatment equipment 18 including the filtration system 20 according to the embodiment. This filtration treatment equipment 18 holds two filtration systems 20 stacked one above the other on a metal frame 19. The above-mentioned locking member (98) is bolted to the frame 19.

The present invention is not limited to the embodiments and examples described above, and configurations different from the embodiments and examples may be adopted within the scope where the configurations of the present invention are applicable. The present invention has specific effects for each aspect described below.

[First aspect]
The first aspect includes a plurality of filtration membrane units (filtration membrane units 21) each including a filtration membrane (filtration membrane 22) and a discharge path for discharging the filtrate obtained by the filtration membrane, and a main pipe part (main pipe part 91) and a plurality of individual water collection channels (individual water collection channels 93) arranged in the axial direction of the main pipe part and communicating with the main pipe part (water collection pipe 90), which includes a plurality of the filtration membranes. A filtration system (filtration system 20) that collects the filtrate filtered by the filtration membrane in each of the units into the main pipe section of the water collection pipe via the discharge path and the individual collection channel of the water collection pipe. A locking member (locking member 98) is provided to lock the movement of the discharge passage in each of the plurality of filtration membrane units in the axial direction, and each of the plurality of filtration membrane units locks the discharge passage in the axial direction. An O-ring (O-ring 16b) made of an elastic material is provided on the outer peripheral surface of the discharge pipe (discharge pipe 16a) to be formed, and when the discharge pipe is inserted into the individual water collection channel, the locking member This is characterized in that the discharge pipe is prevented from moving in the axial direction.

According to this configuration, it is possible to eliminate the need for screw rotation operations when attaching and detaching the filtration membrane unit to and from the water collection pipe, thereby reducing the effort required for maintenance and inspection of the filtration membrane unit.

[Second aspect]
A second aspect is a filtration system having the configuration of the first aspect, wherein the drain pipe of the filtration membrane unit is inserted into the individual water collection channel in which the drain pipe of the filtration membrane unit is not inserted, among the plurality of individual water collection channels in the water collection pipe. The present invention is characterized in that it includes a sealing plug (sealing plug 100) that seals the individual water collection channels.

According to this configuration, even if some of the filtration membrane units are removed from the filtration system due to damage or other reasons, the filtration system can be continued by sealing the individual water collection channels from which the filtration membrane units have been removed with the sealing plugs. Can drive.

[Third aspect]
A third aspect is a filtration system having the configuration of the second aspect, in which the sealing plug has a hook portion (hang portion 101) disposed at the tip end in the axial direction, and a hook portion (hang portion 101) disposed at the center portion in the axial direction. a cylindrical main body part (main body part 103), a handle (handle 105) that projects rearward from the rear end surface of the main body part in the axial direction and extends in the radial direction, and between the hook part and the main body part. a flexible portion (flexible portion 102) located at and capable of flexing in the radial direction; a slope portion (gradient portion 101a) that increases the radial dimension of the main body portion as it goes from the distal end side to the rear end side in the axial direction; and a slope portion that rapidly decreases the radial dimension at the rear end of the slope portion. The water collecting pipe is characterized in that it includes a hooked portion (hooked portion 91a) on which the stepped portion of the hook portion is hooked.

According to this configuration, it is possible to eliminate the need for a screw rotation operation when sealing the individual water collection channel from which the filtration membrane unit has been removed, and to reduce the effort required for maintenance and inspection of the filtration membrane unit.

This application claims priority based on Japanese Patent Application No. 2022-42256, which is a Japanese patent application filed on March 17, 2022, and incorporates all contents described in the Japanese patent application.

20: Filtration system, 21: Filtration membrane unit, 16a: Drain pipe, 90: Water collection pipe, 91: Main pipe part, 91a: Hooked part, 92: Water collection part, 93: Individual collection channel, 98: Locking member, 100: Sealing plug

Claims

A plurality of filtration membrane units each including a filtration membrane and a discharge path for discharging the filtrate obtained by the filtration membrane,
A water collection pipe comprising a main pipe part and a plurality of individual water collection channels arranged in the axial direction of the main pipe part and communicating with the main pipe part,
A filtration system that collects the filtrate filtered by the filtration membrane in each of the plurality of filtration membrane units into the main pipe section of the water collection pipe via the discharge channel and the individual collection channel of the water collection pipe. There it is,
comprising a locking member that locks movement in the axial direction of the discharge passage in each of the plurality of filtration membrane units,
Each of the plurality of filtration membrane units includes an O-ring made of an elastic material on the outer peripheral surface of a discharge pipe forming the discharge channel, and when the discharge pipe is inserted into the individual water collection channel, the A filtration system, characterized in that the discharge pipe is prevented from moving in the axial direction by a locking member.
The filtration system according to claim 1,
It is characterized by comprising a sealing plug that is inserted into the individual water collection channel in which the drain pipe of the filtration membrane unit is not inserted among the plurality of individual water collection channels in the water collection pipe to seal the individual water collection channel. filtration system.
3. The filtration system according to claim 2,
The sealing plug includes a hook portion disposed at an axial tip portion, a cylindrical main body portion disposed at an axial center portion, and protrudes rearward from an axial rear end surface of the main body portion. and a handle extending in the radial direction, and a flexible part located between the hook part and the main body part and capable of bending in the radial direction,
The main body includes an O-ring made of an elastic material on the outer peripheral surface,
The hook portion includes a sloped portion that increases the radial dimension of the main body portion as it goes from the leading end side to the rear end side in the axial direction, and a stepped portion that rapidly decreases the radial dimension at the rear end of the sloped portion. and
The filtration system according to claim 3, wherein the water collection pipe includes a hooked portion on which the stepped portion of the hooked portion is hooked.