Novel steam turbine circulating water filtering device

Abstract

The utility model discloses a novel steam turbine circulating water filtering device which comprises a filtering device body arranged on a steam turbine circulating water pipeline, the steam turbine circulating water pipeline comprises a first pipeline and a second pipeline, and the filtering device body comprises a round box and a sealing cover fixedly installed on the top of the round box in a sealed mode. The left side of the round box is fixedly communicated with the right end of the first pipeline, the right side of the bottom of the round box is fixedly communicated with the top end of the second pipeline, and a round rotating seat is movably sleeved with the round box. By arranging a series of structures, solid slag impurities in circulating water of the steam turbine can be filtered and intercepted, the phenomenon that a large amount of solid slag impurities are introduced into a subsequent steam turbine condenser to cause blockage is avoided, and dirt and slag can be conveniently and rapidly cleaned and discharged and the filter screen cover can be cleaned and dredged without disassembly after the steam turbine condenser is used; and slag removal and cleaning dredging work can be performed without separate disassembly by personnel, so that time and labor are saved, and the use convenience and cleaning efficiency are improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to filter equipment technical field, concretely is a new turbine circulating water filter device. BACKGROUND

[0002] The turbine needs circulating water to cool it when operating, and the circulating water contains impurities, which often causes the condenser heat exchange pipe of the turbine to be blocked, resulting in poor heat exchange and affecting the thermal efficiency of the turbine. In this regard, according to the search structure retrieval report, the announcement number CN215352388U discloses a new turbine circulating water filter device, which comprises a first pipe, a second pipe and a third pipe. The second pipe and the third pipe are detachably and sealingly connected to the two ends of the first pipe, and the second pipe and the third pipe are provided with valves. The first pipe is detachably connected with a filter cartridge.

[0003] The above-mentioned technical disclosure of a new turbine circulating water filter device installs a conical filter cartridge in the pipe, which can filter and intercept the solid residue impurities in the circulating water flow, thereby reducing the subsequent cleaning frequency of the turbine condenser, and subsequently disassembling and cleaning the conical filter cartridge and impurities by disassembling the corresponding pipe. However, there are the following disadvantages in use:

[0004] After use, the conical filter cartridge inside the pipe needs to be disassembled and opened to remove the internal conical filter cartridge for cleaning and residue removal work, which is time-consuming and tedious to operate. It cannot be conveniently and quickly cleaned and residue removed without disassembly, and the use convenience and cleaning efficiency are not ideal. Therefore, it needs to be improved. In view of this, the present application provides a new turbine circulating water filter device to solve the above-mentioned problems. CONTENT OF THE UTILITY MODEL

[0005] The utility model aims at providing a new turbine circulating water filter device to solve the problems raised in the background art.

[0006] To achieve the above object, the utility model provides the following technical scheme: A novel steam turbine circulating water filter device, including the filter device body of setting on the steam turbine circulating water pipeline, the steam turbine circulating water pipeline includes first pipeline and second pipeline, the filter device body includes round box and the cover of sealing fixed mounting at the top of round box, the left side of round box is fixed with the right end of first pipeline, the bottom right side of round box is fixed with the top end of second pipeline, the movable sleeve of round box is set in round box, the left side of round box is provided with the water hole of alignment communication with first pipeline, the filter screen cover is fixedly installed in water hole, the bottom inner wall of water hole is provided with the communication hole of alignment communication with the top end of second pipeline; The filter screen cover is set up for when the steam turbine circulating water is supplied to the water hole in first pipeline, the solid slag impurity in water is filtered and intercepted, and the communication hole is set up for the filtered water to be supplied into the second pipeline to circulate.

[0007] The top right side of the cover is fixedly installed with a PLC controller, and the top of the cover is installed with a positioning rotation driving direction adjusting mechanism electrically connected with the PLC controller and used for driving the rotation of the circular rotating seat, the right side of the round box is embeddedly fixed with an opening and closing residue discharge mechanism electrically connected with the PLC controller, and the opening and closing residue discharge mechanism is horizontally aligned and communicated with the water hole; The positioning rotation driving direction adjusting mechanism is used for driving the circular rotating seat to rotate to one hundred and eighty degrees under the control of the PLC controller, rotating the water hole and the filter screen cover by one hundred and eighty degrees by using the circular rotating seat, so that the two sides are adjusted in direction, the circular rotating seat also drives the communication hole to rotate to the left side and staggered with the second pipeline, temporarily releases the water supply state, realizes the backflushing cleaning and dredging work of the filter screen cover and the water hole by using the water supplied through the first pipeline after adjusting the direction, and the opening and closing residue discharge mechanism is used for automatically discharging the residue for backflushing cleaning under the control of the PLC controller.

[0008] Preferably, the positioning rotation driving direction adjusting mechanism includes a U-shaped seat fixedly connected to the top of the cover, a rotating shaft fixedly connected to the top center of the circular rotating seat is rotatably embedded in the top of the cover, a servo motor with an output shaft fixedly connected to the top end of the rotating shaft is fixedly installed on the top of the U-shaped seat, an inductive positioning assembly is fixedly connected between the outer side of the rotating shaft and the top of the cover, and the inductive positioning assembly and the servo motor are electrically connected with the PLC controller.

[0009] Preferably, the inductive positioning assembly includes an infrared emitting sensor fixedly installed on the right top of the rotating shaft, infrared receiving sensors fixedly connected to the top of the cover are arranged on both sides of the rotating shaft, the infrared receiving sensor on the right side is vertically aligned with the infrared emitting sensor, and the infrared receiving sensor is electrically connected with the PLC controller.

[0010] Preferably, the opening and closing slag discharge mechanism comprises a pollution guide cover fixedly embedded on the right side of the circular box, the left side of the pollution guide cover is transversely aligned and communicated with the water passing hole, and the right side of the pollution guide cover is fixedly communicated with an L-shaped pipe, and the bottom end of the L-shaped pipe is fixedly communicated with an electromagnetic valve electrically connected with the PLC controller.

[0011] Preferably, the top of the PLC controller is fixedly and electrically connected with a prompt lamp, and the PLC controller is a programmed controller with timing function; the prompt lamp is arranged to be controlled to be turned on when the PLC controller receives a corresponding opening slag discharge signal.

[0012] Preferably, the bottom of the cover is fixedly bonded with a sealing ring, and the bottom of the sealing ring is movably contacted with the top of the circular rotating seat and the circular box.

[0013] Preferably, the communication hole is located on the right side of the filter cover.

[0014] Preferably, the top of the cover is provided with a circular perforation, a bearing is fixedly sleeved in the circular perforation, and the inner ring of the bearing is fixedly sleeved with the outer side of the rotating shaft.

[0015] Preferably, the right end of the first pipeline is provided in an arc-shaped structure matched with the outer side of the circular rotating seat, and the right end of the first pipeline is movably attached to the left side of the circular rotating seat.

[0016] Preferably, the top of the circular box is provided with four threaded grooves in a rectangular shape, threaded bolts are threadedly screwed in the threaded grooves, and the top of the cover is provided with four bolt perforations respectively used for movably passing the corresponding threaded bolts.

[0017] Compared with the prior art, the utility model has the advantages that:

[0018] 1. The circular box, the circular rotating seat, the water passing hole, the filter cover, the first pipeline, the communication hole and the second pipeline are matched to filter and intercept the solid slag impurities in the circulating water of the steam turbine, so that the phenomenon of blockage caused by a large amount of solid slag impurities entering the subsequent steam turbine condenser is avoided.

[0019] 2. The circular box, the circular rotating seat, the water passing hole, the filter cover, the first pipeline, the PLC controller, the prompt lamp, the positioning rotary driving direction adjusting mechanism, the induction positioning assembly and the opening and closing slag discharge mechanism are matched to drive the circular rotating seat to rotate by 180 degrees to adjust the direction of the water passing hole and the filter cover after use, to perform back flushing and dredging work by using the water supplied in the first pipeline after the adjustment, and to automatically discharge the sludge during the back flushing and dredging, so that the effect of conveniently and quickly discharging and cleaning the sludge and dredging the filter cover after use is realized, personnel is not required to separately disassemble and clean the sludge and dredge, time and labor are saved, use convenience and cleaning efficiency are improved, and the personnel is reminded to be in the cleaning state.

[0020] The utility model discloses a series of structures are set up, can filter and intercept the solid residue impurity in the steam turbine circulating water, avoid the solid residue impurity and cause the phenomenon of the blockage of a large number of subsequent steam turbine condenser, facilitate in use after the convenient and quick dirt cleaning discharge of dirt and the cleaning of filter screen cover, do not need personnel to open separately and carry out the cleaning of the dirt and the cleaning work, save time and effort, improve the use convenience and cleaning efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0021] Fig. 1 The utility model discloses a novel steam turbine circulating water filter device's structure diagram is shown in figure;

[0022] Fig. 2 The utility model discloses a novel steam turbine circulating water filter device's left view structure diagram is shown in figure;

[0023] Fig. 3 The utility model discloses a novel steam turbine circulating water filter device's main view cross section structure diagram is shown in figure.

[0024] In the drawing: 100, first pipeline;101, second pipeline;1, round box;2, cover;3, round rotary seat;301, water hole;302, filter screen cover;303, communication hole;4, PLC controller;401, prompt lamp;5, U-shaped seat;501, servo motor;502, rotating shaft;503, infrared emission sensor;504, infrared receiving sensor;6, guide dirt cover;601, L-shaped pipe;602, electromagnetic valve. DETAILED DESCRIPTION

[0025] The technical scheme in the embodiments of the utility model will be described clearly and completely below in combination with the drawings in the embodiments of the utility model, and obviously, the described embodiments only are a part of the embodiments of the utility model, not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the ordinary skill in the art without making creative labor all belong to the range of the utility model protection.

[0026] As Figs. 1 to 3As shown, the new steam turbine circulating water filtering device provided by the embodiment comprises a filtering device body arranged on a steam turbine circulating water pipeline, the steam turbine circulating water pipeline comprises a first pipeline 100 and a second pipeline 101, the filtering device body comprises a round box 1 and a cover 2 fixedly and sealingly arranged on the top of the round box 1, four threaded grooves are arranged on the top of the round box 1 in a rectangular shape, and fixed bolts are threadedly screwed in the threaded grooves, four bolt through holes corresponding to the fixed bolts are arranged on the top of the cover 2, and the cover 2 is installed and fixed, the left side of the round box 1 is in communication with the right end of the first pipeline 100, a first installation hole for fixed connection with the outside of the first pipeline 100 is arranged on the inner wall of the left side of the round box 1, the bottom right side of the round box 1 is in communication with the top end of the second pipeline 101, a second installation hole for fixed connection with the outside of the second pipeline 101 is arranged on the bottom right side of the round box 1, a round rotating seat 3 is movably arranged in the round box 1, a water passing hole 301 in alignment with the first pipeline 100 is arranged on the left side of the round rotating seat 3, the right end of the first pipeline 100 is arranged in an arc shape matched with the outside of the round rotating seat 3, the right end of the first pipeline 100 is movably attached to the left side of the round rotating seat 3, a filter screen cover 302 is fixedly installed in the water passing hole 301, a communication hole 303 in alignment with the top end of the second pipeline 101 is arranged on the bottom inner wall of the water passing hole 301, the communication hole 303 is located on the right side of the filter screen cover 302, a sealing ring is fixedly bonded to the bottom of the cover 2, and the bottom of the sealing ring movably contacts the top of the round rotating seat 3 and the round box 1; the filter screen cover 302 is arranged to filter and intercept solid impurities in water when the steam turbine circulating water is supplied to the water passing hole 301 through the first pipeline 100, and the communication hole 303 is arranged to supply the filtered water into the second pipeline 101 for circulation work;

[0027] A PLC controller 4 is fixedly installed on the top right side of the cover 2, a positioning rotation driving and direction adjusting mechanism electrically connected with the PLC controller 4 and used for driving the round rotating seat 3 to rotate is arranged on the top of the cover 2, an opening and closing residue discharging mechanism electrically connected with the PLC controller 4 is fixedly embedded on the right side of the round box 1, and the opening and closing residue discharging mechanism is horizontally aligned with the water passing hole 301; the positioning rotation driving and direction adjusting mechanism is used to drive the round rotating seat 3 to rotate to 180 degrees under the control of the PLC controller 4, the water passing hole 301 and the filter screen cover 302 are driven to rotate 180 degrees by the round rotating seat 3, so that the two sides are adjusted in direction, the round rotating seat 3 also drives the communication hole 303 to rotate to the left side and stagger with the second pipeline 101, temporarily releases the water passing state, and realizes back flushing and cleaning work of the inside of the filter screen cover 302 and the water passing hole 301 by using the adjusted water supplied through the first pipeline 100, and the opening and closing residue discharging mechanism is used to automatically discharge the residue for back flushing and cleaning under the control of the PLC controller 4.

[0028] Specifically, the positioning rotary drive steering mechanism comprises a U-shaped seat 5 fixedly connected to the top of the cover 2, a rotating shaft 502 fixedly connected to the center of the top of the circular rotating seat 3 is rotatably embedded in the top of the cover 2, wherein a circular through hole is formed in the top of the cover 2, a bearing is fixedly sleeved in the circular through hole, the inner ring of the bearing is fixedly sleeved with the outer side of the rotating shaft 502, thereby achieving the effect of rotatably mounting the rotating shaft 502, a servo motor 501 with an output shaft fixedly connected to the top end of the rotating shaft 502 is fixedly installed at the top of the U-shaped seat 5, an inductive positioning assembly is fixedly connected between the outer side of the rotating shaft 502 and the top of the cover 2, and the inductive positioning assembly and the servo motor 501 are electrically connected with the PLC controller 4; the U-shaped seat 5, the rotating shaft 502, the servo motor 501 and the inductive positioning assembly are matched to achieve the effect that when the personnel control the PLC controller 4 to control the servo motor 501 to start in the forward direction, the servo motor 501 drives the rotating shaft 502 to rotate, the rotating shaft 502 drives the circular rotating seat 3 to rotate, the inductive positioning assembly detects the rotation and transmits a corresponding slag discharge signal to the PLC controller 4 when the rotation is one hundred and eighty degrees, and the PLC controller 4 controls the servo motor 501 to be closed, thereby achieving the effect that the circular rotating seat 3 is driven to rotate one hundred and eighty degrees during cleaning, and the effect that the water inlet hole 301 and the filter screen cover 302 are driven to rotate one hundred and eighty degrees to realize two-side steering is achieved, and the water supplied through the first pipeline 100 is used to realize backflushing and cleaning work for the inside of the filter screen cover 302 and the water inlet hole 301.

[0029] Further, the inductive positioning assembly comprises an infrared emitting sensor 503 fixedly installed at the right top of the rotating shaft 502, infrared receiving sensors 504 fixedly connected to the top of the cover 2 are arranged on both sides of the rotating shaft 502, the infrared receiving sensor 504 on the right side is vertically aligned with the infrared emitting sensor 503, and the infrared receiving sensor 504 is electrically connected with the PLC controller 4; the infrared receiving sensor 504 and the infrared emitting sensor 503 are matched, wherein the rotating shaft 502 drives the infrared emitting sensor 503 to rotate when the rotating shaft 502 rotates, the infrared emitting sensor 503 is aligned with the infrared receiving sensor 504 on the left side when the infrared emitting sensor 503 rotates one hundred and eighty degrees, the infrared receiving sensor 504 on the left side receives an infrared signal and transmits a corresponding slag discharge signal to the PLC controller 4, and the infrared receiving sensor 504 on the right side is used for accurate positioning work when the subsequent rotation is reset.

[0030] Further, the opening and closing slag discharge mechanism comprises a pollution guide cover 6 embedded and fixed on the right side of the circular box 1, the left side of the pollution guide cover 6 is transversely aligned and communicated with the water passage hole 301, the right side of the pollution guide cover 6 is fixedly communicated with an L-shaped pipe 601, the bottom end of the L-shaped pipe 601 is fixedly communicated with an electromagnetic valve 602 electrically connected with the PLC controller 4; the pollution guide cover 6, the L-shaped pipe 601 and the electromagnetic valve 602 are arranged in cooperation, the PLC controller 4 also controls the electromagnetic valve 602 to be opened when receiving the corresponding slag discharge opening signal, at this time, the pollution slag in the filter cover 302 and the water passage hole 301 cleaned by back flushing is sequentially discharged outward through the pollution guide cover 6, the L-shaped pipe 601 and the electromagnetic valve 602, the electromagnetic valve 602 is connected with an external slag collecting box through an external pipeline, so that the pollution slag is conveniently and quickly cleaned and discharged after use, and the filter cover 302 is cleaned.

[0031] Further, the top of the PLC controller 4 is fixedly and electrically connected with a prompt lamp 401, the PLC controller 4 is a programmed controller with timing function; the prompt lamp 401 is arranged to be controlled to be opened when the PLC controller 4 receives the corresponding slag discharge opening signal, so that personnel can clearly know that the cleaning state.

[0032] The use method of the embodiment is that when the steam turbine circulating water is supplied into the water passage hole 301 through the first pipeline 100, the solid slag impurities in the water are filtered and intercepted on the left side of the filter cover 302, the filtered water is supplied into the second pipeline 101 through the communication hole 303 to flow, the solid slag impurities are filtered and intercepted, so that the solid slag impurities are not massively introduced into the subsequent steam turbine condenser to cause the blocking phenomenon, and the effect of filtering the steam turbine circulating water is realized.

[0033] The PLC controller 4 is preset to control the prompt lamp 401 and the electromagnetic valve 602 to be opened for thirty seconds when a corresponding slag discharge signal is received, and to be reset after thirty seconds. When the solid slag impurities and the filter screen cover 302 need to be cleaned after use, a person controls the PLC controller 4 to control the servo motor 501 to be started in the forward direction, the servo motor 501 drives the rotating shaft 502 to rotate, the rotating shaft 502 drives the circular rotating seat 3 to rotate, the circular rotating seat 3 drives the water passage hole 301 and the filter screen cover 302 to rotate, the circular rotating seat 3 also drives the communication hole 303 to rotate to the left side and be staggered with the second pipeline 101, and the water passage state is temporarily released. When the rotating shaft 502 rotates, the infrared emitter sensor 503 also rotates. When the infrared emitter sensor 503 rotates to be aligned with the left side infrared receiver sensor 504, it is rotated by one hundred and eighty degrees. At this time, the water passage hole 301 and the filter screen cover 302 are rotated by one hundred and eighty degrees, so that the two sides are adjusted. The left side infrared receiver sensor 504 receives the infrared signal and transmits it to the PLC controller 4 to open the corresponding slag discharge signal. At this time, the PLC controller 4 controls the servo motor 501 to be closed, and controls the prompt lamp 401 and the electromagnetic valve 602 to be opened for thirty seconds. After the one hundred and eighty degree adjustment is completed, the steam turbine circulating water continues to run. At this time, the water supplied through the first pipeline 100 is used to realize the backflushing and cleaning work of the filter screen cover 302 and the water passage hole 301. The solid slag is flushed out to the right, and the filter screen cover 302 is backflushed and cleaned. The sludge formed by the flushing and cleaning is sequentially discharged to the outside through the guide cover 6, the L-shaped pipe 601 and the electromagnetic valve 602. The electromagnetic valve 602 is connected to the outside sludge collection box through an external pipeline. The effect of convenient and rapid cleaning and discharge of sludge and cleaning and dredging of the filter screen cover 302 after use is realized. Personnel do not need to separately disassemble and clean the sludge and clean the dredging work, which saves time and effort and improves the use convenience and cleaning efficiency.

[0034] After thirty seconds, the PLC controller 4 controls the prompt lamp 401 and the electromagnetic valve 602 to be closed, and controls the servo motor 501 to be reset in the reverse direction to drive the circular rotating seat 3 to rotate back to the reset position, drive the water passage hole 301 and the filter screen cover 302 to rotate back to the reset position, and drive the communication hole 303 to rotate back to the reset position to be aligned with the second pipeline 101 again. The circulating water supply and circulation work can continue. Through the prompt lamp 401 which is opened together when the sludge is cleaned and discharged, it is convenient for personnel to know that it is in the cleaning state.

[0035] Finally, it should be noted that: the above only for the preferred embodiments of the present application, and is not intended to limit the present application, although the foregoing embodiments of the present application have been described in detail, for the skilled in the art, it still can be modified, or for the equivalent replacement of part of the technical features of the technical solutions recorded in the foregoing embodiments. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application, shall be included within the scope of the present application.

Claims

1. A novel steam turbine circulating water filtering device, comprising a filtering device body arranged on a steam turbine circulating water pipeline, the steam turbine circulating water pipeline comprising a first pipeline (100) and a second pipeline (101), characterized in that: The filter device body comprises a round box (1) and a cover (2) fixedly installed on the top of the round box (1), the left side of the round box (1) is fixedly communicated with the right end of a first pipeline (100), the right bottom of the round box (1) is fixedly communicated with the top end of a second pipeline (101), a circular rotating seat (3) is movably sleeved in the round box (1), the left side of the circular rotating seat (3) is provided with a water passing hole (301) aligned and communicated with the first pipeline (100), a filter screen cover (302) is fixedly installed in the water passing hole (301), and a communication hole (303) aligned and communicated with the top end of the second pipeline (101) is formed in the bottom inner wall of the water passing hole (301). A PLC controller (4) is fixedly installed on the right top of the cover (2), a positioning rotation driving and direction adjusting mechanism is installed on the top of the cover (2) and electrically connected with the PLC controller (4) and used for driving the circular rotating seat (3) to rotate, an opening and closing residue discharging mechanism electrically connected with the PLC controller (4) is fixedly embedded on the right side of the round box (1), and the opening and closing residue discharging mechanism is transversely aligned and communicated with the water passing hole (301).

2. A novel turbine cycle water filtration device according to claim 1, characterized in that: The positioning rotation driving and direction adjusting mechanism comprises a U-shaped seat (5) fixedly connected to the top of the cover (2), a rotating shaft (502) fixedly connected to the top center of the circular rotating seat (3) is rotatably embedded on the top of the cover (2), a servo motor (501) with an output shaft fixedly connected to the top end of the rotating shaft (502) is fixedly installed on the top of the U-shaped seat (5), an inductive positioning assembly is fixedly connected between the outer side of the rotating shaft (502) and the top of the cover (2), and the inductive positioning assembly and the servo motor (501) are electrically connected with the PLC controller (4).

3. A novel turbine cycle water filtration device as claimed in claim 2, wherein: The inductive positioning assembly comprises an infrared emitting sensor (503) fixedly installed on the right top of the rotating shaft (502), infrared receiving sensors (504) fixedly connected to the top of the cover (2) are arranged on the two sides of the rotating shaft (502), the infrared receiving sensor (504) on the right side is vertically aligned with the infrared emitting sensor (503), and the infrared receiving sensor (504) is electrically connected with the PLC controller (4).

4. A new type of turbine circulating water filter device according to claim 1, characterized in that: The opening and closing residue discharging mechanism comprises a pollution guide cover (6) fixedly embedded on the right side of the round box (1), the pollution guide cover (6) is transversely aligned and communicated with the water passing hole (301) on the left side, an L-shaped pipe (601) is fixedly communicated on the right side of the pollution guide cover (6), and an electromagnetic valve (602) electrically connected with the PLC controller (4) is fixedly communicated on the bottom end of the L-shaped pipe (601).

5. A novel turbine cycle water filtration device as claimed in claim 1, wherein: A prompt lamp (401) is fixedly and electrically connected on the top of the PLC controller (4), and the PLC controller (4) is a programmed controller with timing function.

6. A new type of turbine cycle water filtering device according to claim 1, characterized in that: A sealing ring is fixedly bonded on the bottom of the cover (2), and the bottom of the sealing ring is movably contacted with the top of the circular rotating seat (3) and the round box (1).

7. A new type of turbine cycle water filter device according to claim 1, characterized in that: The communication hole (303) is located on the right side of the filter screen cover (302).

8. A new type of turbine cycle water filter device according to claim 2, characterized in that: A circular perforation is formed in the top of the cover (2), a bearing is fixedly sleeved in the circular perforation, and the inner ring of the bearing is fixedly sleeved with the outer side of the rotating shaft (502).

9. A new type of turbine cycle water filter device according to claim 1, characterized in that: The right end of the first pipeline (100) is provided with an arc-shaped structure matched with the outer side of the circular rotating seat (3), and the right end of the first pipeline (100) is movably attached to the left side of the circular rotating seat (3).

10. A new type of turbine cycle water filtering device according to claim 1, characterized in that: The top of the circular box (1) is provided with four threaded grooves in a rectangular shape, and the threaded grooves are threadedly connected with fixing bolts; and the top of the cover (2) is provided with four bolt through holes for movably passing the corresponding fixing bolts.

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