CN117665212A - Laboratory electrochemical active membrane test cross-flow membrane module - Google Patents

Abstract

The invention provides an electrochemical active membrane testing cross-flow membrane component for a laboratory, which is prepared from an organic glass shell, an electrochemical active membrane, conductive titanium wires, counter electrode platinum wires and a rubber sealing ring. The upper and lower shells are penetrated and fastened by nuts and screws, and the outer sealing ring is embedded in the outer groove of the lower cavity shell to seal the upper cavity shell with the lower shell. One end of the platinum wire disc in the cavity of the upper cavity is positioned at the top of the cavity of the upper shell and used as a counter electrode, and the other end of the platinum wire disc penetrates through the upper shell and extends out of the shell to be connected with a power supply. The electrochemical active membrane is positioned in the lower cavity shell and used as a working electrode, the inner sealing ring is pressed on the outer edge of the electrochemical active membrane, one end of the titanium wire of the lower cavity is annularly distributed and embedded into the inner wall of the lower cavity shell, the titanium wire is contacted with the outer edge of the electrochemical active membrane to conduct electricity, and the other end of the titanium wire penetrates out of the lower shell to be connected with a power supply. The concentrated solution flows out from the cross-flow outlet during filtration, and the permeate solution flows out from the permeate outlet after being filtered by the electrochemical active membrane. The invention has reasonable design, easy observation, suitability for organic and inorganic films and simple processing.

Description

Laboratory electrochemical active membrane test cross-flow membrane module

Technical Field

The invention relates to the technical field of electrochemistry, in particular to an electrochemical active membrane testing cross-flow membrane component for a laboratory.

Background

The electrochemical active membrane can simultaneously carry out electrochemical oxidation reaction and membrane filtration process, and provides a reliable method for effectively improving mass transfer efficiency through flow-through electrolysis operation, and compared with mechanical stirring and side-flow electrolysis, the mass transfer rate can be enhanced by convection in flow-through electrolysis. Therefore, the electrochemical active membrane has wide application prospect in the water purification fields such as pollutant removal, self-cleaning membrane, resource recovery, sea water desalination and the like, but related matched experimental equipment still does not have unified standard or commercial products, and the industrial application cannot be guided to be amplified. Compared with other types of filter membranes, the electrochemical active membrane has the characteristics that the separation process and the electrochemical reaction process are integrated, specific oxidation and filtration conditions are provided under the action of voltage, and the pollutant degradation reaction rate and selectivity are improved. For a thin film type electrochemical active membrane evaluation device, the design difficulty of an electrochemical active membrane component used in the current pilot experiment mainly lies in how to connect a lead with an internal electrochemical active membrane and a counter electrode under a sealing condition and the problem of setting the counter electrode. The film type electrochemical active film generally adopts an organic or inorganic film which is used as a working electrode to bear electrochemical oxidation and filtration, so that the two functions of film conduction and filtration are required to meet design requirements simultaneously, and in the aspect of conduction, since the film is difficult to load an electroactive layer on one side and insulate the other side in the preparation process, the film is used as a working electrode and a bipolar separator of a counter electrode, and the short circuit risk exists. If the counter electrode is located remotely from the working electrode, in the form of an electrolytic cell within the membrane module, short-circuiting problems can be avoided, which requires a rational layout of the working electrode, reference electrode and counter electrode locations within the membrane module.

Disclosure of Invention

According to the technical problem, a cross-flow membrane module for testing electrochemical active membranes in a laboratory is provided. The invention uses transparent organic glass, titanium, platinum, rubber and other materials to process laboratory electrochemical active film test cross-flow film component, the reactor is mainly composed of two parts: the housing and the working electrode electrochemically active membrane may be disassembled. The detachable shell is screwed on four hard plastic screws to penetrate and fasten the shell, the outer sealing ring is embedded in the outer groove of the lower cavity shell, the upper cavity shell is sealed with the lower cavity shell, a platinum wire in the upper cavity is led into the shell from the outer side of the upper cavity shell, one end of the platinum wire is positioned at the top of the upper cavity shell and used as a counter electrode, the other end of the platinum wire penetrates through the upper shell to extend out of the shell and be connected with a power supply, the feed inlet and the cross flow outlet are positioned at the upper cavity shell to form 90 degrees, a good cross flow condition is formed, the permeate outlet is positioned below the electrochemical active touch groove of the working electrode of the lower cavity and is horizontal to the cross flow outlet, one end of the titanium wire of the lower cavity is annularly distributed and embedded in the inner wall of the lower cavity shell and is in contact with the outer edge of the electrochemical active film to conduct electricity, and the other end of the platinum wire penetrates out of the outer connecting power supply conductive film of the lower cavity shell and supports the filter film to be embedded in the conductive film groove of the lower cavity shell. The chemical active membrane is positioned in the lower cavity shell and used as a working electrode, the inner sealing ring is pressed on the outer edge of the electrochemical active membrane, and the feeding side leakage is sealed and prevented from being permeated on the conducting membrane by hydraulic pressure.

The invention adopts the following technical means:

a laboratory electrochemically active membrane test cross-flow membrane module comprising: the electrochemical active membrane comprises a detachable shell, an electrochemical active membrane, a first electrode and a conductive unit, wherein the detachable shell comprises an upper cavity shell and a lower cavity shell, the upper cavity shell and the lower cavity shell are detachably connected, and the upper cavity shell and the lower cavity shell are sealed through a sealing structure;

the electrochemical active membrane is arranged in the lower cavity shell and used as a working electrode, and is close to the joint of the upper cavity shell and the lower cavity shell to separate the upper cavity shell and the lower cavity shell; the electrochemical active membrane and the inner part of the upper cavity shell form a first cavity, and the electrochemical active membrane and the inner part of the lower cavity shell form a second cavity;

one end of the first electrode is arranged at the top of the side wall of the upper cavity shell and is used as a counter electrode, and the other end of the first electrode penetrates through the upper cavity shell and extends out of the shell to be connected with a power supply;

one end of the conductive unit is embedded into the inner wall of the lower cavity shell to be in contact with the outer edge of the electrochemical active membrane for conduction, and the other end of the conductive unit penetrates out of the lower cavity shell to be connected with a power supply;

the end part of the upper cavity shell, which is far away from the lower cavity shell, is provided with a feed inlet, and the side wall of the upper cavity shell is provided with a cross flow outlet; the feeding port and the cross flow outlet are communicated with the first chamber; the side wall of the lower cavity shell is provided with a permeate outlet which is communicated with the second cavity; the feed liquid enters from the feed inlet, and when in filtration, the concentrated solution flows out from the cross flow outlet, and the clear liquid flows out from the permeate outlet after being filtered by the electrochemical active membrane.

Further, the first electrode is a platinum wire disc in the cavity of the upper cavity, and the conductive material of the first electrode is selected as a platinum wire; and the platinum wire disc in the cavity of the upper cavity is subjected to spiral wiring.

Further, the conductive unit is a conductive titanium wire, and the conductive material is selected as the titanium wire; one end annular wiring of the conductive unit is embedded into the inner wall of the lower cavity shell.

Further, the sealing structure comprises an outer sealing ring, an outer groove is formed in the end face of the joint of the lower cavity shell and the upper cavity shell, the outer sealing ring is embedded in the outer groove, and the upper cavity shell and the lower cavity shell are in sealing connection to form a first seal.

Further, the sealing structure further comprises an inner sealing ring, wherein the inner sealing ring is pressed on the outer edge of the electrochemical active membrane, the electrochemical active membrane is fixed in the lower cavity shell, and meanwhile, a second seal is formed between the upper cavity shell and the lower cavity shell.

Further, the inner sealing ring and the outer sealing ring are both rubber sealing rings.

Further, the feeding port and the cross-flow outlet are arranged at 90 degrees, so that cross-flow filtration is realized.

Further, the detachable housing is manufactured by transparent organic glass.

Further, the detachable shell is fastened by a plurality of groups of nuts and screws in a penetrating manner to the upper cavity shell and the lower cavity shell, the nuts are respectively screwed on the hard plastic screws, a plurality of first mounting holes are formed in the upper cavity shell, a plurality of second mounting holes are formed in the lower cavity shell, and the screws are connected in the coaxial first mounting holes and the coaxial second mounting holes in a matched manner.

Compared with the prior art, the invention has the following advantages:

the organic glass reactor has clear light transmission and clear structure, can observe experimental phenomena, can be disassembled and removed from the upper shell and the lower shell, and can flexibly expand the effective volume of the reactor besides cleaning the internal space of the reactor. The upper shell and the lower shell are sealed by the outer sealing rings, and the feed inlet and the cross flow outlet form 90 degrees, so that good conditions are provided for the cross flow environment. The inner conductive material of the upper cavity is selected to be a platinum wire, and the lower cavity is selected to be a titanium wire, so that on one hand, the manufacturing cost can be reduced, and on the other hand, the material is excellent in conductivity and corrosion-resistant, and good conductivity and stability are provided for subsequent experiments. The sealing adopts the rubber ring, and sealing effect is superior to the silica gel plate, is difficult for causing dense water seepage to clear water side accident, only need unscrew nut can the membrane change operation, convenient and fast. The reactor can be used for laboratory electrochemical active membrane test cross-flow membrane condition small-scale research, and is an excellent laboratory electrochemical active membrane test cross-flow membrane reactor design scheme.

For the reasons, the invention can be widely popularized in the fields of electrochemical active membrane testing and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to the drawings without inventive effort to a person skilled in the art.

FIG. 1 is an exploded schematic view of a laboratory electrochemical active membrane test cross-flow membrane module housing and membrane module of the present invention.

Fig. 2 is a front view of fig. 1.

Fig. 3 is a side view of fig. 1.

Fig. 4 is a top view of fig. 1.

Fig. 5 is a schematic view of the fastened housing of the present invention.

Fig. 6 is a schematic view of a lower chamber assembly of the present invention, wherein (a) is a front view, (b) is a side view, (c) is a top view, and (d) is an isometric view.

Fig. 7 is a schematic view of an upper chamber assembly of the present invention, wherein (a) is a front view, (b) is a side view, (c) is a top view, and (d) is an isometric view.

Fig. 8 is a schematic diagram of a membrane exchange process of the membrane module of the present invention, wherein (a) is a front view, (b) is a side view, (c) is a top view, and (d) is an isometric view.

In the figure: 1. a nut; 2. conductive titanium wires; 3. a lower chamber housing; 4. a permeate outlet; 5. an electrochemically active membrane; 6. an inner seal ring; 7. an outer seal ring; 8. a platinum wire disc in the cavity of the upper cavity; 9. an upper chamber housing; 10. a cross-flow outlet; 11. a feed inlet; 12. and (3) a screw.

Detailed Description

It should be noted that, without conflict, the embodiments of the present invention and features of the embodiments may be combined with each other. The invention will be described in detail below with reference to the drawings in connection with embodiments.

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present invention. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless it is specifically stated otherwise. Meanwhile, it should be clear that the dimensions of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

In the description of the present invention, it should be understood that the azimuth or positional relationships indicated by the azimuth terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal", and "top, bottom", etc., are generally based on the azimuth or positional relationships shown in the drawings, merely to facilitate description of the present invention and simplify the description, and these azimuth terms do not indicate and imply that the apparatus or elements referred to must have a specific azimuth or be constructed and operated in a specific azimuth, and thus should not be construed as limiting the scope of protection of the present invention: the orientation word "inner and outer" refers to inner and outer relative to the contour of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

In addition, the terms "first", "second", etc. are used to define the components, and are only for convenience of distinguishing the corresponding components, and the terms have no special meaning unless otherwise stated, and therefore should not be construed as limiting the scope of the present invention.

The invention provides a cross-flow membrane module for testing an electrochemical active membrane in a laboratory, namely a small-scale membrane module which can be used in the laboratory for evaluating the simultaneous oxidation and filtration of the electrochemical active membrane. The invention can solve the problem that the double sides of the thin film type electrochemical active film are conductive and are easy to short circuit during testing.

As shown in fig. 1-8, the electrochemical active membrane testing cross-flow membrane assembly for the laboratory comprises an electrochemical active membrane testing cross-flow membrane assembly consisting of a nut 1, a conductive titanium wire 2, a lower cavity shell 3, a permeate outlet 4, an electrochemical active membrane 5, an inner sealing ring 6, an outer sealing ring 7, an upper cavity inner platinum wire disc 8, an upper cavity shell 9, a cross-flow outlet 10, a feed inlet 11 and a screw 12 in fig. 1-4.

The electrochemical active membrane testing cross-flow membrane component for the laboratory is made of an organic glass shell (a lower cavity shell 3 and an upper cavity shell 9), a working electrode electrochemical active membrane 5, a conductive titanium wire 2, a counter electrode platinum wire (an upper cavity platinum wire disc 8) and a rubber sealing ring (an inner sealing ring 6 and an outer sealing ring 7), wherein the upper and lower shells are penetrated and fastened by a nut 1 and a screw 12, the upper cavity shell 9 and the lower cavity shell 3 are detachably connected, the upper cavity shell 9 and the lower cavity shell 3 are sealed through a sealing structure, the outer sealing ring 7 is embedded in an outer groove of the lower cavity shell 3, the upper cavity shell 9 and the lower cavity shell 3 are sealed, and feeding side leakage during filtration is prevented from overflowing the shell. One end of the platinum wire disc 8 in the upper cavity is positioned at the top of the upper cavity shell 9 to be used as a counter electrode, and the other end passes through the upper cavity shell 9 to extend out of the shell to be connected with a power supply. The electrochemical active membrane 5 is positioned in the lower cavity shell 3 and used as a working electrode, and is pressed on the outer edge of the electrochemical active membrane 5 by the inner sealing ring 6, so that the feed side is sealed and prevented from leaking into the permeate. The installation position of the electrochemical active membrane 5 is close to the joint of the upper cavity shell 9 and the lower cavity shell 3, the upper cavity shell 9 and the lower cavity shell 3 are separated, a first cavity is formed inside the electrochemical active membrane 5 and the upper cavity shell 9, and a second cavity is formed inside the electrochemical active membrane 5 and the lower cavity shell 3. One end of the lower cavity conductive titanium wire 2 is embedded into the inner wall of the lower cavity shell 3 in an annular wiring way, is in contact with the outer edge of the electrochemical active membrane 5 and is conductive, and the other end of the lower cavity conductive titanium wire penetrates out of the lower cavity shell 3 to be connected with a power supply. The end part of the upper cavity shell 9 far away from the lower cavity shell 3 is provided with a feed inlet 11, and the side wall is provided with a cross flow outlet 10; the feed inlet 11 and the cross flow outlet 10 are communicated with the first chamber; the side wall of the lower cavity shell 3 is provided with a permeate outlet 4, and the permeate outlet 4 is communicated with the second cavity. The feed inlet 11 forms 90 degrees with the cross flow outlet 10, during filtration, feed liquid enters from the feed inlet 11, concentrated solution flows out from the cross flow outlet 10, and clear liquid flows out from the permeate outlet 4 after being filtered by the electrochemical active membrane 5. The reactor has reasonable design, clear internal structure, can be observed from the outside, fully considers two experimental processes of electrochemistry and cross-flow membrane filtration, is suitable for organic and inorganic membranes, and has simple processing.

The whole electrochemical active membrane testing cross-flow membrane component is fastened by penetrating the screw rod 12 and the nut 1, the whole casing is processed by using an organic glass plate with the thickness of 2cm, the upper cavity casing 9 and the lower cavity casing 3 are processed in the same way, 4 holes are drilled at equal intervals for penetrating the screw rod 12, the outer sealing ring 7 is embedded in an outer groove of the lower cavity casing 3 to play a sealing role, and the feeding side leakage is prevented from overflowing the casing during filtering. The inner conductive wires of the shell are made of titanium and platinum metal materials, the diameters of the two conductive metal wires are the same, one end of the lower cavity conductive titanium wire 2 is embedded into the inner wall of the lower cavity shell 3 in an annular wiring manner, the lower cavity conductive titanium wire is in contact with the outer edge of the electrochemical active film 5 to conduct electricity, and the other end of the lower cavity conductive titanium wire penetrates out of the lower cavity shell 3 to be connected with a power supply, and the specific processing mode is shown in figure 6. One end of the platinum wire disc 8 in the upper cavity is positioned at the top of the upper cavity shell 9 to be used as a counter electrode, and the other end passes through the upper cavity shell 9 to extend out of the shell to be connected with a power supply, and the specific processing mode is shown in figure 7. The electrochemical active membrane 5 is positioned in the lower cavity shell 3 and used as a working electrode, and is pressed on the outer edge of the electrochemical active membrane 5 by the inner sealing ring 6, so that the feed side is sealed and prevented from leaking into the permeate. In order to make the outer edge of the lower cavity conductive titanium wire 2 and the outer edge of the electroactive membrane (electrochemical active membrane 5) contact and conduct so as to ensure a conductive path and not to influence the membrane filtration process, on the one hand, in order to make the counter electrode platinum wire (the platinum wire disc 8 in the upper cavity) and the electrochemical active membrane 5 be placed relatively and kept at a distance so as to avoid short circuit, and spiral wiring, the counter electrode area is increased, the risk of oxidation corrosion of the two electrodes is reduced, and the conductive performance of the assembly is greatly improved. The feed liquid is got into from feed inlet 11, and the thick liquid has the electron through the platinum wire dish 8 in the upper chamber body cavity, and under cross-flow filtration's effect, difficult deposit mud, thick liquid flows out by cross-flow export 10, and the filtrate passes through electrochemically active membrane 5, and under electrochemistry and membrane filtration's effect, the permeate flows out by permeate export 4, and whole membrane module can dismantle, and sealing performance is superior under the rubber ring effect. When the membrane is replaced, only the membrane component is required to be disassembled, residues in the component and residues on the sieve plate are cleaned, the filter membrane is placed on the electrochemically active membrane sieve plate, the component is spliced and fastened, the membrane can be replaced conveniently while the component is not damaged, and the specific membrane replacing process is shown in figure 8.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the invention.

Claims (9)

1. A laboratory electrochemical active membrane test cross-flow membrane module comprising: the electrochemical active membrane comprises a detachable shell, an electrochemical active membrane (5), a first electrode and a conductive unit, wherein the detachable shell comprises an upper cavity shell (9) and a lower cavity shell (3), the upper cavity shell (9) is detachably connected with the lower cavity shell (3), and the upper cavity shell (9) and the lower cavity shell (3) are sealed through a sealing structure;

the electrochemical active membrane (5) is arranged in the lower cavity shell (3) and is used as a working electrode, and is close to the joint of the upper cavity shell (9) and the lower cavity shell (3) to separate the upper cavity shell (9) from the lower cavity shell (3); the electrochemical active membrane (5) and the inner part of the upper cavity shell (9) form a first cavity, and the electrochemical active membrane (5) and the inner part of the lower cavity shell (3) form a second cavity;

one end of the first electrode is arranged at the top of the side wall of the upper cavity shell (9) and used as a counter electrode, and the other end of the first electrode penetrates through the upper cavity shell (9) and extends out of the shell to be connected with a power supply;

one end of the conductive unit is embedded into the inner wall of the lower cavity shell (3) to be in contact with the outer edge of the electrochemical active membrane (5) for conduction, and the other end of the conductive unit penetrates out of the lower cavity shell (3) to be connected with a power supply;

the end part of the upper cavity shell (9) far away from the lower cavity shell (3) is provided with a feed inlet (11), and the side wall is provided with a cross flow outlet (10); the feeding port (11) and the cross flow outlet (10) are communicated with the first cavity; the side wall of the lower cavity shell (3) is provided with a permeate outlet (4), and the permeate outlet (4) is communicated with the second cavity; the feed liquid enters from the feed inlet (11), and during filtration, the concentrated solution flows out from the cross flow outlet (10), and the clear liquid flows out from the permeate outlet (4) after being filtered by the electrochemical active membrane (5).

2. The laboratory electrochemically active membrane test cross-flow membrane assembly according to claim 1, characterized in that the first electrode is an upper cavity inner platinum wire disc (8) of which the electrically conductive material is selected as platinum wire; and the platinum wire disc (8) in the cavity of the upper cavity is subjected to spiral wiring.

3. The laboratory electrochemically active membrane test cross-flow membrane module according to claim 1, characterized in that the conductive unit is a conductive titanium wire (2), the conductive material of which is selected as titanium wire; one end annular wiring of the conductive unit is embedded into the inner wall of the lower cavity shell (3).

4. The laboratory electrochemical active membrane testing cross-flow membrane assembly according to claim 1, wherein the sealing structure comprises an outer sealing ring (7), an outer groove is formed in the end face of the joint of the lower cavity shell (3) and the upper cavity shell (9), the outer sealing ring (7) is embedded in the outer groove, and the upper cavity shell (9) and the lower cavity shell (3) are in sealing connection to form a first seal.

5. The laboratory use electrochemically active membrane testing cross-flow membrane assembly according to claim 4, characterized in that the sealing structure further comprises an inner sealing ring (6), the inner sealing ring (6) pressing against the outer edge of the electrochemically active membrane (5) securing the electrochemically active membrane (5) within the lower chamber housing (3) while forming a second seal between the upper chamber housing (9) and the lower chamber housing (3).

6. The laboratory-use electrochemically active membrane test cross-flow membrane assembly according to claim 5, characterized in that both the inner sealing ring (6) and the outer sealing ring (7) are rubber sealing rings.

7. The laboratory electrochemically active membrane test cross-flow membrane module according to claim 1, characterized in that the feed inlet (11) is arranged at 90 ° to the cross-flow outlet (10) for cross-flow filtration.

8. The lab-on-electrochemically active membrane test cross-flow membrane module of claim 1, wherein the detachable housing is fabricated from transparent organic glass.

9. The laboratory electrochemical active membrane testing cross-flow membrane assembly according to claim 1, wherein the detachable housing is fastened by a plurality of groups of nuts (1) and screws (12) in a penetrating manner, the plurality of nuts (1) are respectively screwed on the plurality of hard plastic screws (12), wherein the upper cavity housing (9) is provided with a plurality of first mounting holes, the lower cavity housing (3) is provided with a plurality of second mounting holes, and the screws (12) are connected in the first mounting holes and the second mounting holes in a matching manner.