CN218924322U - Hollow fiber membrane module - Google Patents

Abstract

The utility model relates to the technical field of hollow fiber membranes, in particular to a hollow fiber membrane assembly, which comprises a shell structure and a filter element, wherein each hollow fiber membrane comprises a first membrane layer and a second membrane layer which are distributed from outside to inside in a double-layer manner, the pore size of the surface wall of the first membrane layer is larger than that of the surface wall of the second membrane layer, an air inlet of a flow guide cavity is connected with an external pressure device through a back flushing pipe and an electromagnetic valve, and attachments on the outer wall of the first membrane layer can be removed by pressurizing in a first channel when the electromagnetic valve is in an open state; through fixedly being equipped with a plurality of guide plates that are used for going forward, returning the direction along axial direction with rivers on its inside wall of casing, play the effect of vortex, prolonged the cycle that the filter core was stopped up, double-deck hollow fiber membrane structure can be for the bigger filtration area of inboard rete to can prolong the rete by the time of jam, with the cycle of increase clearance filter core.

Description

Hollow fiber membrane module

Technical Field

The utility model relates to the technical field of hollow fiber membranes, in particular to a hollow fiber membrane assembly

Background

Hollow fiber membranes are membranes that are fibrous in shape and have a self-supporting function. The hollow fiber membrane is a fiber yarn which is processed into a hollow inner cavity by taking polysulfone and dimethylacetamide as raw materials, and has selective permeation characteristics by combining a membrane layer of a high-permeability polymer. The outer diameter of the hollow fiber yarn is generally 500-600 pum, the inner diameter is 200-300 pum, the fiber bundle made into 3-6 m is put into a high pressure resistant metal shell, one end of the fiber bundle is sealed, and the other end is bonded together by epoxy resin with a special formula, so as to carry out industrial water treatment.

When the prior art hollow fiber membrane component filters stock solution, the pores on the surface wall of the hollow fiber membrane can influence the separation effect due to the blockage of suspended matters contained in the stock solution, especially, the water flow speed on one side of the component far away from the water inlet is slow, so that the blockage caused by the accumulation of the suspended matters is more obvious, and the pressure difference between the membranes of the hollow fiber membrane is rapidly increased, so that the continuous operation cannot be realized. In addition, in the single-layer hollow fiber membrane structure, after the suspended matters are attached to the surface wall, separation treatment cannot be performed, so that the surface to which the suspended matters are attached is relatively small, the membrane is blocked, and frequent cleaning is required.

Disclosure of Invention

In view of the drawbacks of the prior art, a first aspect of the present utility model proposes a hollow fiber membrane module comprising:

the shell structure is internally provided with a cavity, the side wall of the shell structure is provided with a water inlet used for being connected with a water supply pipeline, and the upper end and the lower end of the shell structure are respectively provided with a water outlet and a sewage outlet which are communicated with the cavity;

the filter element is arranged in the cavity and comprises a first packaging plate and a second packaging plate which are arranged at the upper end and the lower end in the shell structure, and a plurality of hollow fiber membranes are fixedly arranged between the first packaging plate and the second packaging plate;

each hollow fiber membrane comprises a first membrane layer and a second membrane layer which are distributed from outside to inside, wherein a second channel is formed in the second membrane layer, the first membrane layer is coated on the outer side of the second membrane layer along the axial direction, a first channel is formed between the first membrane layer and the second membrane layer, and the pore size of the surface wall of the first membrane layer is larger than that of the surface wall of the second membrane layer;

the first end of the second channel is communicated with the water outlet, the second end of the second channel is fixed and blocked by the second packaging plate, the first end of the first channel is fixed and blocked by the first packaging plate, a flow guide cavity communicated with the second end of the second channel is formed in the second packaging plate, an air inlet of the flow guide cavity is connected with an external pressure device through a backwashing pipe and an electromagnetic valve, and attachments on the outer wall of the first film layer can be removed by pressurizing in the first channel when the electromagnetic valve is in an open state;

and a drain valve for switching off the communication between the cavity and the drain outlet is arranged on the second packaging plate.

Preferably, the pore size of the surface wall of the first film layer is set to be 100% -110% of the pore size of the surface wall of the second film layer.

Preferably, a plurality of guide plates for guiding the water flow back and forth along the axial direction are fixedly arranged on the inner side wall of the shell structure.

Preferably, the guide pieces include a first guide piece guiding the water to the drain direction and a second guide piece guiding the water to the drain direction, the first guide piece and the second guide piece being alternately distributed on the inner wall peripheral side of the housing structure.

Preferably, the guide piece is arranged in a V shape or a circular arc shape.

Preferably, the hollow fiber membranes are disposed parallel to or at an angle to the housing structure axis direction.

Preferably, the included angle between the hollow fiber membrane and the axial direction of the shell structure is smaller than 15 degrees.

Preferably, the second packaging plate comprises a fixing sealing plate and a packaging frame fixed on the periphery of the fixing sealing plate in a sealing and cladding mode, the guide cavity is formed in the fixing sealing plate, a connecting pipe communicated with the guide cavity is arranged on the packaging frame, and the connecting pipe is detachably connected with the backwashing pipe.

Preferably, the blow-off valve is fixedly arranged on the fixed sealing plate and is positioned in the gap between the hollow fiber membranes.

Compared with the prior art, the hollow fiber membrane component and the using method have the remarkable advantages that:

1. according to the utility model, the guide plates for guiding the water flow to and from the axial direction are fixedly arranged on the inner side wall of the shell, so that the turbulent flow effect is realized, the suspended matters are driven to be fully mixed in the cavity, the filter element is prevented from being quickly blocked due to the partial accumulation in the cavity, the suspended matters can be fully mixed in the cavity, the problem of quick attachment speed of the suspended matters in the partial accumulation is relieved, and the blocked period of the filter element is prolonged;

2. according to the utility model, by arranging the double-layer hollow fiber membrane structure, the inner membrane layer is arranged to be consistent with the size of the existing hollow fiber membrane, the outer membrane layer can play a role in prefiltering, and a larger filtering area is provided relative to the inner membrane layer, so that the blocking time of the membrane layer can be prolonged, and the period of cleaning the filter element can be prolonged;

3. according to the utility model, the second packaging plate with the diversion cavity is arranged, the diversion cavity in the second packaging plate is externally connected with the pressure device, and the pressure medium enters between the two film layers from the diversion cavity, so that the attachment on the surface of the inner film layer can be impacted, and the attachment on the outer wall of the outer film layer can be removed by pressing from inside to outside, so that the attachment on the surface of the hollow fiber film is cleaned, and a good cleaning effect is achieved.

Drawings

The drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures may be represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing.

FIG. 1 is a schematic side view of a hollow fiber membrane module according to an embodiment of the present utility model.

Fig. 2 is a schematic view showing the internal structure of a hollow fiber membrane module according to an embodiment of the present utility model.

Fig. 3 is a schematic view showing the internal structure of a housing in a hollow fiber membrane module according to an embodiment of the present utility model.

FIG. 4 is a schematic cross-sectional view of the hollow fiber membrane and the first and second package plates in the hollow fiber membrane module according to the embodiment of the utility model.

Fig. 5 is a schematic cross-sectional view of the structure of fig. 4 in the direction A-A.

Fig. 6 is a schematic sectional view of the structure of fig. 4 in the direction B-B.

FIG. 7 is an enlarged schematic view of a partial structure of the air flow direction inside the second package plate in the hollow fiber membrane module according to the embodiment of the present utility model.

Detailed Description

For a better understanding of the technical content of the present utility model, specific examples are set forth below, along with the accompanying drawings.

At present, for filtration of coal chemical wastewater, as the flow velocity of raw water in the hollow fiber membrane component is gradually reduced from the inlet direction, suspended matters are more easily accumulated on one side of the component far away from the inlet, and under the action of continuous water pressure, the accumulated suspended matters are attached to the surface of the hollow fiber membrane and block pores on the surface wall of the hollow fiber membrane, so that the pressure difference between membranes of the hollow fiber membrane is rapidly increased, and the continuous operation cannot be realized.

[ hollow fiber Membrane Module ]

As shown in fig. 1 and 2, the present utility model provides a hollow fiber membrane module, which aims to extend the clogging period of the hollow fiber membrane module and to make the cleaning of attachments on the surface of the hollow fiber membrane easier, the module mainly comprising a housing structure 1 and a filter element.

The housing structure 1 has a chamber 101 for accommodating the filter element therein, a water inlet 14 for connecting with a water supply pipe is formed on a side wall of the housing structure, and a water outlet 121 and a sewage outlet 131 which are communicated with the chamber 101 are respectively formed at upper and lower ends of the housing structure.

Further, the housing structure 1 includes a hollow housing 11, and a first end cap 12 and a second end cap 13 screw-mounted at both ends of the housing 11.

In a specific embodiment, the casing 11 is a cylindrical body made of stainless steel and having a circular, rectangular or polygonal cross section, threaded connectors 111 are respectively arranged at the upper end and the lower end of the cylindrical body and are used for being in threaded connection with the first end cover 12 and the second end cover 13, the first end cover 12 and the second end cover 13 are respectively made of stainless steel and are respectively in a bucket shape, the middle positions of the first end cover 12 and the second end cover 13 are respectively provided with a water outlet 121 and a drain 131, and when the cylindrical body is installed, first sealing rings 113 are respectively arranged between the first end cover 12, the second end cover 13 and the casing 11 so as to keep good sealing performance among the casing 11, the first end cover 12 and the second end cover 13.

Further, a plurality of guide pieces 112 for guiding the water flow in the axial direction are fixedly provided on the inner side wall of the housing 11.

As shown in fig. 3, in the preferred embodiment, the guide pieces 112 include a first guide piece 112a for guiding the water toward the drain 131 and a second guide piece 112b for guiding the water toward the drain 121, and the first guide piece 112a and the second guide piece 112b are alternately disposed on the inner wall circumference side of the housing structure 1.

Optionally, the guiding sheet 112 is configured in a V shape or a circular arc shape, and when the water flow enters the chamber 101 from the water inlet 14, the water flows along the inner wall of the housing 11 and contacts the first guiding sheet 112a and the second guiding sheet 112b distributed in the forward and reverse directions, so that the water flow flows back and forth in the axial direction, plays a role of turbulence, and drives suspended matters to be fully mixed in the chamber 101, thereby avoiding rapid blockage of the filter element caused by local accumulation in the chamber 101.

Therefore, the problem that the flow velocity of the water in the cavity 101 is high at the inlet end and the flow velocity of the water at the other end is low is avoided, so that the water flows back and forth in the cavity 101 to disturb the flow, suspended matters can be fully mixed in the cavity 101, the problem that the suspended matters are deposited and attached at a local part is fast is slowed down, and the period that the filter element is blocked is prolonged.

As shown in fig. 2, the filter element is disposed in the chamber 101, and the filter element includes a first package plate 4 and a second package plate 5 disposed at upper and lower ends inside the housing structure 1, and a plurality of hollow fiber membranes 3 are fixedly mounted between the first package plate 4 and the second package plate 5.

Each hollow fiber membrane 3 comprises a first membrane layer 31 and a second membrane layer 32 which are distributed from outside to inside in a double-layer manner, a second channel 302 is formed in the second membrane layer 32, the first membrane layer 31 is coated on the outer side of the second membrane layer 32 along the axial direction, a first channel 301 is formed between the first membrane layer 31 and the second membrane layer 32, and the pore size of the surface wall of the first membrane layer 31 is larger than that of the surface wall of the second membrane layer 32.

In a specific embodiment, the hollow fiber membrane 3 is an ultrafiltration membrane, and is made of polysulfone, polyethersulfone, polyvinylidene fluoride or polyacrylonitrile, the filtration precision is in the range of 0.005-0.01 μm, the outer diameter of the second membrane layer 32 is 0.4-2.0mm, the inner diameter is 0.3-1.4mm, the outer diameter of the first membrane layer 31 is 1.2-3.0mm, the inner diameter is 0.8-2.4mm, and the pore size of the surface wall of the first membrane layer 31 is set to 100% -110% of the pore size of the surface wall of the second membrane layer 32.

In this way, the second membrane layer 32 is set to be consistent with the size of the existing hollow fiber membrane 3, and the first membrane layer 31 is arranged on the outer side of the second membrane layer 32 to play a role in prefiltering, and provide a larger filtering area relative to the second membrane layer 32, so that the time for which the second membrane layer 32 is blocked can be prolonged, and the period for cleaning the filter element can be prolonged.

Further, as shown in fig. 2 and 4, the first ends of the hollow fiber membranes 3 are fixed by the first packaging plate 4, the second ends are fixed by the second packaging plate 5, and the first packaging plate 4 and the second packaging plate 5 are encapsulated by epoxy resin to form a plate body;

wherein the first end of the first film 31 is fixed in the first package plate 4 and the first end of the first channel 301 is blocked by the first package plate 4, the first end of the second film 32 is fixed in the first package plate 4 and the first end of the second channel 302 is communicated with the drain port 121;

a diversion cavity 501 distributed along the horizontal position is formed in the second packaging plate 5, and the air inlet of the diversion cavity 501 is connected with an external pressure device through a backwashing pipe 2 and an electromagnetic valve 21;

the second end of the first membrane layer 31 is fixed in the second package plate 5 and the second end of the first channel 301 is brought into communication with the flow guiding cavity 501, the second end of the second membrane layer 32 is fixed by the second package plate 5 through the flow guiding cavity 501 and the second end of the first channel 301 is blocked by the second package plate 5.

In this way, when the solenoid valve 21 is in the open state, the pressure can be applied to the first channel 301, the internal pressure can impact the attached matter on the surface of the second membrane layer 32, and the attached matter on the outer wall of the first membrane layer 31 can be removed by applying pressure from the pores on the surface wall of the first membrane layer 31, so that the attached matter on the surface of the hollow fiber membrane 3 can be cleaned.

Referring to fig. 4 to fig. 7, in a specific embodiment, the second package board 5 includes a fixed sealing board 51 and a package frame 52 fixed on the periphery of the fixed sealing board 51 in a sealing and wrapping manner, a diversion cavity 501 is formed in the fixed sealing board 51, a connection pipe 521 communicated with the diversion cavity 501 is disposed on the package frame 52, and the connection pipe 521 is detachably connected with the backwash pipe 2.

Wherein, the fixed sealing plate 51 is encapsulated by epoxy resin to form a circular plate body, the inside of the circular plate body is provided with an annular hollow structure extending towards the peripheral side wall, namely a diversion cavity 501, the packaging frame 52 is a stainless steel hoop, is clamped at the outer side of the fixed sealing plate 51 along the peripheral side, and is provided with a second sealing ring 53 so as to ensure good sealing performance of the diversion cavity 501.

In order to facilitate the introduction of pressure medium into the flow guiding cavity 501, the outer wall of the packaging frame 52 is provided with an integrally formed connecting pipe 521, the connecting pipe 521 can penetrate through a pipe hole 102 reserved on the outer wall of the shell 11, a sealing ring is also arranged between the connecting pipe 521 and the pipe hole 102, tightness is ensured, one end of the connecting pipe 521 extending out of the shell 11 is connected with a backwashing pipe 2, and the backwashing pipe 2 is connected with an external pressure device through an electromagnetic valve 21.

In a specific embodiment, the external pressure device is configured as an air pump or a water pump, and is capable of providing a water pressure or air pressure of 0.1-0.2Mpa, and is capable of introducing pressure medium into the diversion cavity 501 in a continuous pressure supply or a pulse pressure supply manner.

In this way, the pressure medium enters the first channel 301 from the flow guiding cavity 501, can impact the attachment on the surface of the second membrane layer 32, and can press outwards from the pores on the surface wall of the first membrane layer 31 to remove the attachment on the outer wall of the first membrane layer 31, so that the attachment on the surface of the hollow fiber membrane 3 is cleaned, and a better cleaning effect is achieved.

Further, in order to facilitate the discharge of the cleaned suspended solids, a drain valve 54 for breaking the communication between the chamber 101 and the drain 131 is installed on the second package plate 5.

In a specific embodiment, the blow-off valve 54 is fixedly arranged on the fixed sealing plate 51 and is positioned in the gap between the hollow fiber membranes 3, the blow-off valve 54 is opened and closed in an electrically controlled manner by an electromagnetic valve, when the arrangement gap between the hollow fiber membranes 3 is larger than the blow-off valve 54, the positions of the blow-off valve 54 are arbitrarily arranged, and the hollow fiber membranes 3 are arranged in parallel to the axial direction of the shell structure 1.

In an alternative embodiment, when the arrangement gap between the hollow fiber membranes 3 is smaller than the blow-off valve 54, the blow-off valve 54 is preferentially disposed at the intermediate position of the fixed seal plate 51, and the arrangement of the hollow fiber membranes 3 on the fixed seal plate 51 is more compact with respect to the one end of the first package plate 4.

As shown in fig. 4, the hollow fiber membranes 3 are disposed at an angle of less than 15 degrees with respect to the axial direction of the housing structure 1 due to the clearance provided for installing the drain valve 54 in the intermediate position. In this example, the included angle is set to 10-12 °.

In a preferred embodiment, the end surface of the sealing plate 51 on the side away from the drain 131 may be configured in a bucket shape to facilitate the drainage.

In combination with the above embodiment, by arranging the double-layer membrane structure, the diameter of the outer membrane structure is larger than that of the existing membrane structure, the pore size is the same as or less than 10% of that of the inner membrane, the effect of prefiltering is achieved, a relatively larger filtering area is provided, the cleaning period is delayed, the speed of locally accumulating and attaching suspended matters is slowed down by matching with the guide plate 112 on the inner wall of the shell 11, and the period of blocking the filter element is further prolonged.

[ method for Using hollow fiber Membrane Module ]

An exemplary use of the hollow fiber membrane module in combination with the example shown in fig. 1 includes raw water essence and a cartridge cleaning (rinsing) step.

Raw water purification

The water inlet 14 is communicated with a raw water supply mechanism, raw water enters the chamber 101 and then collides with the guide plate 112 for a plurality of times to achieve a turbulence effect, so that water flows back and forth in the chamber 101 to be disturbed, suspended matters can be fully mixed in the chamber 101, the problem that the suspended matters are accumulated and attached locally at a high speed is solved, and the period that the filter element is blocked is prolonged; thus, the suspended matter impurities in the water flow are filtered after passing through the pores of the surface walls of the first membrane layer 31 and the second membrane layer 32 in sequence and then the purified water flows and is discharged to the water outlet 121 through the second channel 302.

Because the pore size of the surface wall of the first membrane layer 31 is set to 100% -110% of the pore size of the surface wall of the second membrane layer 32, most of suspended matters can be isolated by the first membrane layer 31, so that the second membrane layer 32 is not easy to be blocked, the corresponding surface area of the first membrane layer 31 is larger, the cleaning period is longer, and when in cleaning, the inner and outer double-layer membrane layers can be cleaned simultaneously, so that the hollow fiber membrane 3 with the double-layer composite structure has a better filtering effect.

Filter element cleaning

When the pressure drop of the water outlet 121 exceeds the initial value of 0.05Mpa, the hollow fiber membrane 3 needs to be cleaned, an external pressure device, such as a pressure pump or a pressure fan, is connected through the backwash pipe 2 and the electromagnetic valve 21, the switch connected with the water inlet 14 is closed, the drain valve 54 is opened, the electromagnetic valve 21 is opened to guide the pressure medium into the diversion cavity 501, and the pressure inside the diversion cavity 501 is kept at 0.1-0.2Mpa for 1-2 minutes, so that the pressure medium enters the first channel 301 from the diversion cavity 501.

Referring to fig. 7, the pressure medium can impact the attached matter on the surface of the second membrane layer 32, and can press and remove the attached matter on the outer wall of the first membrane layer 31 from the pores on the surface wall of the first membrane layer 31, so that the attached matter on the surface of the hollow fiber membrane 3 is cleaned and discharged from the pores on the surface wall of the first membrane layer 31.

According to an embodiment of the utility model, a rinsing process of the chamber 101 is also included.

As an alternative embodiment, after the solenoid valve 21 is closed, a switch connected to the water inlet 14 is opened, the hollow fiber membrane 3 is rinsed with raw water, suspended matter impurities in the chamber 101 are rinsed out from the drain valve 54 after 1 to 2 minutes, and then the drain valve 54 is closed, and the raw water is purified again.

Wherein the pressure medium comprises water, gas or a mixture of water and gas, and the pressure medium is fed continuously or in pulses.

In the preferred embodiment, when the pressure medium is a mixture of water and air and the feeding mode is a pulse mode, the cleaning effect on the attachments on the surfaces of the first film layer 31 and the second film layer 32 is best, and the efficiency is high.

While the utility model has been described with reference to preferred embodiments, it is not intended to be limiting. Those skilled in the art will appreciate that various modifications and adaptations can be made without departing from the spirit and scope of the present utility model. Accordingly, the scope of the utility model is defined by the appended claims.

Claims (10)

1. A hollow fiber membrane module, comprising:

the shell structure (1) is internally provided with a cavity (101), the side wall of the shell structure is provided with a water inlet (14) which is connected with a water supply pipeline, and the upper end and the lower end of the shell structure are respectively provided with a water outlet (121) and a sewage outlet (131) which are communicated with the cavity (101);

the filter element is arranged in the cavity (101) and comprises a first packaging plate (4) and a second packaging plate (5) which are arranged at the upper end and the lower end inside the shell structure (1), and a plurality of hollow fiber membranes (3) are fixedly arranged between the first packaging plate (4) and the second packaging plate (5);

each hollow fiber membrane (3) comprises a first membrane layer (31) and a second membrane layer (32) which are distributed from outside to inside, a second channel (302) is formed in the second membrane layer (32), the first membrane layer (31) is coated on the outer side of the second membrane layer (32) along the axial direction, a first channel (301) is formed between the first membrane layer (31) and the second membrane layer (32), and the pore size of the surface wall of the first membrane layer (31) is larger than or equal to that of the surface wall of the second membrane layer (32);

the first end of the second channel (302) is communicated with the water outlet (121), the second end of the second channel is fixed and blocked by the second packaging plate (5), the first end of the first channel (301) is fixed and blocked by the first packaging plate (4), a diversion cavity (501) communicated with the second end of the second channel (302) is formed in the second packaging plate (5), an air inlet of the diversion cavity (501) is connected with an external pressure device through a backwashing pipe (2) and an electromagnetic valve (21), and attachments on the outer wall of the first film layer (31) can be removed by pressurizing in the first channel (301) when the electromagnetic valve (21) is in an open state;

and a drain valve (54) for switching off the communication between the cavity (101) and the drain outlet (131) is arranged on the second packaging plate (5).

2. Hollow fiber membrane module according to claim 1, characterized in that the pore size of the surface walls of the first membrane layer (31) is set to 100-110% of the pore size of the surface walls of the second membrane layer (32).

3. Hollow fiber membrane module according to claim 1, characterized in that a plurality of guide plates (112) for guiding the water flow in the axial direction back and forth are fixedly provided on the inner side wall of the housing structure (1).

4. A hollow fiber membrane module according to claim 3, wherein the guide sheet (112) comprises a first guide sheet (112 a) for guiding the water flow toward the drain port (131) and a second guide sheet (112 b) for guiding the water flow toward the drain port (121), the first guide sheet (112 a) and the second guide sheet (112 b) being alternately distributed on the inner wall peripheral side of the housing structure (1).

5. The hollow fiber membrane module according to claim 4, wherein the guide piece (112) is provided in a "V" shape or a circular arc shape.

6. Hollow fiber membrane module according to claim 1, characterized in that the hollow fiber membranes (3) are arranged parallel to the housing structure (1) axis direction or at an angle to the housing structure (1) axis direction.

7. The hollow fiber membrane module according to claim 6, characterized in that the hollow fiber membrane (3) is at an angle of less than 15 degrees to the axial direction of the housing structure (1).

8. The hollow fiber membrane module according to claim 1, wherein the second package plate (5) comprises a fixed sealing plate (51) and a package frame (52) fixed on the periphery of the fixed sealing plate (51) in a sealing and cladding manner, the guide cavity (501) is formed in the fixed sealing plate (51), a connection pipe (521) communicated with the guide cavity (501) is arranged on the package frame (52), and the connection pipe (521) is detachably connected with the backwash pipe (2).

9. Hollow fiber membrane module according to claim 8, characterized in that the blow down valve (54) is fixedly arranged on the stationary sealing plate (51) in the gap between the hollow fiber membranes (3).

10. The hollow fiber membrane module according to claim 1, wherein the hollow fiber membrane is an ultrafiltration membrane made of polysulfone, polyethersulfone, polyvinylidene fluoride or polyacrylonitrile, the filtration accuracy is in the range of 0.005-0.01 μm, the outer diameter of the second membrane layer (32) is 0.4-2.0mm, the inner diameter is 0.3-1.4mm, the outer diameter of the first membrane layer (31) is 1.2-3.0mm, and the inner diameter is 0.8-2.4mm.

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