A spraying mechanism and a desulfurization tower with the spraying mechanism

Abstract

The present application relates to waste gas treatment technical field, especially to a kind of spraying mechanism and the desulfurization tower with the spraying mechanism, comprising: pedestal, with annular cavity in, with outside slurry inlet pipeline communication;Multiple first nozzles, fixed on pedestal, including with annular cavity communication liquid inlet seat, with liquid inlet seat communication liquid inlet disc, set on liquid inlet disc and with liquid inlet disc interior communication multiple spray ports;Liquid inlet seat has spiral plate in, the axial direction of spiral plate is parallel with the liquid inlet direction of liquid inlet seat, liquid inlet disc has cylindrical cavity in.Slurry is input to annular cavity from slurry inlet pipeline, then flow through liquid inlet seat with spiral plate, after liquid inlet disc makes slurry spray from spray port, slurry is under the action of centripetal force of spiral plate, quickly spray to form mist spray.The present application is communicated with multiple first nozzles by annular cavity, need not install multiple pipes and multiple layers of nozzle, under the pressure of a group of high-pressure pumps, dense mist is sprayed, that is, energy consumption can be reduced to realize uniform spraying.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of waste gas treatment, and in particular to a spraying mechanism and a desulfurization tower with the spraying mechanism. BACKGROUND

[0002] The desulfurization tower is a device for desulfurization treatment of industrial waste gas. At present, the flue gas desulfurization method is mainly used for the treatment of sulfur contained in waste gas. The specific working process is that the limestone slurry sprayed by multiple nozzles in the desulfurization tower is mixed with the flue gas entering the desulfurization tower, and the sulfur oxide in the flue gas is absorbed, and the sulfur oxide in the liquid phase reacts with calcium carbonate to form calcium sulfite.

[0003] In the prior art, in order to improve the spraying effect of the nozzle, a multi-layer nozzle is usually used, for example, a desulfurization tower spraying system disclosed in the Chinese Utility Model Patent with the authorization announcement No. CN206008435U was published on March 15, 2017. By setting a layer of spraying device and a layer of spraying device in the spray tower, the distribution of the mist is more dense, and the desulfurization is more thorough.

[0004] However, the inventor found that when the multi-layer spraying method is used to spray the dense mist, multiple high-pressure pumps are needed to achieve it, resulting in high energy consumption. SUMMARY

[0005] In view of at least one of the above technical problems, the present application provides a spraying mechanism and a desulfurization tower with the spraying mechanism, which improves the spraying effect and reduces the energy consumption by improving the spraying structure.

[0006] According to a first aspect of the present application, a spraying mechanism is provided, comprising:

[0007] a base having an annular cavity therein, the annular cavity being in communication with an external slurry inlet pipeline;

[0008] a plurality of first nozzles fixed on the base, the first nozzle comprising a liquid inlet seat in communication with the annular cavity, a liquid inlet disc in communication with the liquid inlet seat, and a plurality of spray ports provided on the liquid inlet disc and in communication with the interior of the liquid inlet disc;

[0009] wherein the liquid inlet seat has a spiral plate therein, the axial direction of the spiral plate being parallel to the liquid inlet direction of the liquid inlet seat, and the liquid inlet disc has a cylindrical cavity therein.

[0010] Further, the liquid inlet seat is in the shape of a circular truncated cone, and the cross-sectional diameter thereof gradually decreases in the direction away from the base.

[0011] Further, the spray port is in the shape of a conical tube.

[0012] Further, the base has two opposite parallel installation surfaces, the first nozzles are installed on one of the installation surfaces, and the second nozzles are installed on the other installation surface.

[0013] Further, the second nozzle comprises a fixed tube, a stopper, a driving disc and a spray head, the spray head is connected with the fixed tube, and the driving disc is arranged to be relatively rotatable between the fixed tube and the spray head.

[0014] The fixed tube has a sliding groove arranged at the end of the fixed tube and towards the center, the stopper is adapted to the sliding groove and arranged to be relatively movable in the sliding groove, the driving disc has an arc-shaped slot arranged towards the center and obliquely, and the stopper has a connecting column extending into the arc-shaped slot.

[0015] Further, the second nozzles are arranged in a circle on the base, the diameter of the driving disc is greater than that of the spray head, and the outer periphery of the driving disc is uniformly provided with teeth.

[0016] The driving mechanism for driving the second nozzles to move synchronously is further included.

[0017] The driving mechanism comprises a gear ring engaged with the driving disc of the second nozzle, and a driving member for driving the gear ring to rotate.

[0018] Further, the driving member comprises a gear, which is driven by hand or by a motor.

[0019] According to the second aspect of the present application, a desulfurization tower with the spraying mechanism is further provided, which comprises:

[0020] A tower body, the tower body has a slurry pool at the bottom;

[0021] The spraying mechanism is arranged in the tower body, and the tower body further has a liquid pump in communication with the slurry pool, and the liquid pump is in communication with a slurry inlet pipeline;

[0022] A flue gas inlet is arranged on the tower body and in communication with the inside of the tower body and below the spraying mechanism;

[0023] A flue gas outlet is arranged on the tower body and in communication with the inside of the tower body and above the spraying mechanism.

[0024] Further, the desulfurization tower further comprises:

[0025] A demister is arranged above the spraying mechanism;

[0026] A guide plate is obliquely fixed in the inside of the tower body and used for guiding the treated flue gas to the flue gas outlet.

[0027] Further, the flue gas inlet and the flue gas outlet each comprise a bellows in communication with the tower body at one end, and a positioning block fixedly installed on the other end of the bellows, the tower body is provided with a fixing plate extending to the outside of the positioning block, the fixing plate is provided with a positioning arc groove, and the positioning block extends into the positioning arc groove and is positioned at any position of the positioning arc groove by a fastener.

[0028] The present application has the advantages that: the pulp is input into the annular cavity from the pulp inlet pipeline, then flows through the liquid inlet seat with spiral plates, and finally is sprayed out from the spray nozzles through the liquid inlet disc. Under the action of the centripetal force of the spiral plates, the pulp is quickly sprayed out to form mist spray. The annular cavity is in communication with a plurality of first spray nozzles, without the need to install multiple pipelines and multiple layers of spray nozzles, and under the pressure of a group of high-pressure pumps, dense mist can be sprayed out, thereby reducing energy consumption and achieving uniform spraying. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0030] Figure 1 It is a structural schematic view of the spraying mechanism in the embodiment of the present application.

[0031] Figure 2 It is a sectional view of the first spray nozzle in the embodiment of the present application.

[0032] Figure 3 It is a structural schematic view of the first spray nozzle in the embodiment of the present application.

[0033] Figure 4 It is a structural schematic view of the second spray nozzle in the embodiment of the present application.

[0034] Figure 5 It is an exploded structural schematic view of the second spray nozzle in the embodiment of the present application.

[0035] Figure 6 It is a structural schematic view of the conveying mechanism in the embodiment of the present application.

[0036] Figure 7 It is a structural schematic view of the desulfurization tower in the embodiment of the present application.

[0037] Figure 8 It is an internal structural schematic view of the desulfurization tower with the spraying mechanism in the embodiment of the present application. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application.

[0039] It should be noted that when an element is referred to as being "fixed" to another element, it can be directly on the other element or there can be an intervening element. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or there can be an intervening element. The terms "vertical", "horizontal", "left", "right", and similar terms as used herein are for purposes of description only and are not intended to be limiting.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the application herein is for describing particular embodiments only and is not intended to be limiting. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0041] As shown in the spraying mechanism, comprising a base 1 and a plurality of first nozzles 11, please refer to Figures 1 to 6 : Figure 1 :

[0042] Base 1, the base 1 has a ring cavity, the ring cavity is communicated with the outside inlet pipe 33. As Figure 1 shown, the inlet pipe 33 is connected with the ring cavity in the base 1, in some embodiments of the present application, by a way of communicating with the base 1 having a ring cavity through an inlet pipe 33, under the action of a group of high pressure pumps, the slurry flows to the base 1 through the inlet pipe, realizing the spraying work of the spraying mechanism.

[0043] A plurality of first nozzles 11, fixed on the base 1, the first nozzle 11 includes a liquid inlet seat 11a communicated with the ring cavity, a liquid inlet disc 11b communicated with the liquid inlet seat 11a, a plurality of spray ports 11c arranged on the liquid inlet disc 11b and communicated with the inside of the liquid inlet disc 11b. Please refer to Figure 2 , Figure 3 As shown, a plurality of first nozzles 11 are fixed on the base 1, the liquid inlet seat 11a below the nozzle is communicated with the base 1, the liquid inlet disc 11b is arranged above the nozzle, and a plurality of spray ports 11c are arranged in the inside of the liquid inlet disc 11b. In some embodiments of the present application, the slurry enters the first nozzle 11 through the ring cavity inside the base 1, flows through the liquid inlet seat 11a, and is sprayed out through the plurality of spray nozzles in the inside of the liquid inlet disc 11b, so that the distribution of the mist is more dense and the desulfurization effect is more thorough.

[0044] As shown in FIG. 1, the liquid inlet seat 11a has a spiral plate 11d inside, the axial direction of the spiral plate 11d is parallel to the liquid inlet direction of the liquid inlet seat 11a, and the liquid inlet disc 11b has a cylindrical cavity inside. Please continue to refer to Figure 2 As shown in FIG. 1, the liquid inlet seat 11a has a spiral plate 11d inside, the axial direction of the spiral plate 11d is parallel to the liquid inlet direction of the liquid inlet seat 11a, and the liquid inlet disc 11b has a cylindrical cavity inside. Please continue to refer to

[0045] In the specific implementation of the present spraying mechanism, the slurry is input from the slurry inlet pipe 33 to the annular cavity of the base 1 through the pressure pump, the annular cavity is communicated with the plurality of first nozzles 11, the slurry enters the plurality of first nozzles 11, and due to the spiral plate 11d in the first nozzle 11, the slurry quickly flows into the cylindrical cavity of the liquid inlet disc 11b under the centrifugal force of the spiral plate 11d, the cylindrical cavity is communicated with the plurality of spray ports 11c, and finally the slurry is sprayed out of the plurality of spray ports 11c inside the liquid inlet disc 11b to form dense spray. The present application is communicated with the plurality of first nozzles 11 through one slurry inlet pipe 33, without the need to install multiple pipes and multiple layers of nozzles, and under the pressure of one group of high-pressure pumps, relatively dense mist is sprayed out, thereby reducing energy consumption and realizing uniform spraying.

[0046] In some embodiments of the present application, the liquid inlet seat 11a is in the shape of a circular truncated cone, and the cross-sectional diameter gradually decreases in the direction away from the base 1. As shown in FIG. 1, Figure 2 、 Figure 3 As shown in FIG. 1, the liquid inlet seat 11a has a large inlet and a small outlet, and is in the shape of a circular truncated cone. Through the above arrangement, on the one hand, the flow of slurry is facilitated, and on the other hand, due to the gradual reduction of the cross-sectional diameter, the flow rate of the slurry increases from the inlet to the outlet, the spray is finer, and the spraying effect is better.

[0047] Further, the spray port 11c is in the shape of a conical tube. Please continue to refer to Figure 2 As shown in FIG. 1, the spray port 11c is in the shape of a conical tube with a large inlet and a small outlet. When the slurry enters the liquid inlet disc 11b through the cylindrical cavity, the conical tube shape of the spray port 11c is used to continuously increase the flow rate of the slurry. In some embodiments of the present application, the cross-sectional area of the liquid inlet seat 11a and the spray port 11c gradually decreases and the spiral plate 11d is used to increase the flow rate of the slurry, so that the slurry sprayed out of the spray port 11c is sprayed out at high speed to form relatively dense mist.

[0048] In some embodiments of the present application, the base 1 has two opposite parallel mounting surfaces, the plurality of first nozzles 11 are mounted on one of the mounting surfaces, and the other mounting surface also has a plurality of second nozzles 12, and the spraying flow of the second nozzles 12 is adjustably arranged. As shown in FIG. 1, Figure 1As shown, the base 1 has two installation surfaces, the upper installation surface has the first nozzle 11, and the lower installation surface has the second nozzle 12. Through the above arrangement, the pulp can be delivered to the two layers of nozzles through one pulp inlet pipe 33. It should be noted that in the embodiments of the present application, the installation can have various forms, such as welding, riveting, or screwing, etc. The upper and lower relationship of the first nozzle 11 and the second nozzle 12 can also be adjusted to the structure form that the first nozzle 11 is below and the second nozzle 12 is above. The spray flow of the second nozzle 12 can be adjusted and arranged, so that when the impurity content in the flue gas or the flow of the flue gas is different, the spray flow can be adjusted according to the proportion, so that the spraying effect is optimized while the energy consumption is reduced.

[0049] Regarding the arrangement of the second nozzle 12, the second nozzle 12 includes a fixed pipe 12a, a block 12b, a driving disc 12c, and a spray head 12d. The spray head 12d is connected with the fixed pipe 12a, and the driving disc 12c is relatively rotatably arranged between the two. For details, please refer to Figure 5 As shown, one side of the fixed pipe 12a is communicated with the base 1, and the other side is connected with the spray head 12d. Between the spray head 12d and the fixed pipe 12a, there are the driving disc 12c and the block 12b.

[0050] For details, please refer to Figure 5 As shown, the end of the fixed pipe 12a has a chute 12a1 which is arranged towards the center at equal intervals. The block 12b is adapted to the chute 12a1 and is relatively movably arranged in the chute 12a1. The driving disc 12c has an arc-shaped groove 12c1 which is arranged towards the center. The block 12b has a connecting column 12b1 which extends into the arc-shaped groove 12c1. Through the above arrangement that the block 12b has the connecting column 12b1 which extends into the arc-shaped groove 12c1 of the driving disc 12c, and the end of the fixed pipe 12a has the chute 12a1 which is adapted to the block 12b, when the driving disc 12c is rotated, the position of the connecting column 12b1 in the arc-shaped groove 12c1 changes, thereby driving the block 12b to move in the chute 12a1, realizing the change of the shielding area of the block 12b to the fixed pipe 12a, and thereby realizing the adjustment of the flow. When the driving disc 12c drives the block 12b to move, the block 12b slides in the chute 12a1 to adjust the spray flow. It should be noted that the connecting column 12b1 has various structure forms, for example, it can be the structure form of the pin as shown in Figure 5 , it can also be a screw, a rivet, or a protruding structure arranged on the block 12b.

[0051] In some embodiments of the present application, a plurality of second nozzles 12 are arranged in a circular manner on the base 1. The diameter of the driving disc 12c is greater than that of the spray head 12d, and the outer periphery of the driving disc 12c is uniformly distributed with teeth 12c2. As shown in Figure 4 , Figure 6As shown, in order to make the multiple second nozzles 12 form a dense spray layer when spraying, and achieve the best effect on the spraying of flue gas, the multiple second nozzles 12 are arranged in a circular shape on the base 1. In order to control the spraying flow of the multiple second nozzles 12 at the same time, the diameter of the driving disc 12c is larger than the nozzle 12d, and the outer periphery of the driving disc 12c is uniformly distributed with teeth 12c2, which can control the flow of the second nozzle 12 by starting the teeth 12c2 of the disc. The spraying mechanism further comprises a driving mechanism 2 for driving the multiple second nozzles 12 to move synchronously.

[0052] As shown in Figure 6 , the driving mechanism 2 comprises a gear ring 21 engaged with the driving disc 12c on the multiple second nozzles 12, and further comprises a driving member 22 for driving the gear ring 21 to rotate. Please continue to refer to Figure 6 , the driving member 22 is engaged with the outside of the gear ring 21, the inner ring of the gear ring 21 is engaged with the teeth 12c2 of the driving disc 12c of the multiple second nozzles 12, the driving member 22 drives the gear ring 21 to rotate, the gear ring 21 rotates to drive the driving disc 12c to rotate, the driving disc 12c drives the stop block 12b to move, thereby adjusting the spraying flow of the second nozzle 12. By synchronously driving the multiple second nozzles 12 through a gear ring 21 to adjust the flow, the rapid synchronous adjustment of the flow is realized. It should be pointed out here that in the embodiment of the application, the driving member 22 comprises a gear, and the gear rotation has multiple forms, which can be driven by manual or motor or other multiple rotation modes.

[0053] According to another aspect of the embodiment of the application, a desulfurization tower with the spraying mechanism is also provided, as shown in Figure 7 , Figure 8 , comprising:

[0054] The tower body 3 has a slurry pool 31 at the bottom for storing limestone slurry with a proportioned ratio.

[0055] As shown in Figure 8 , the spraying mechanism described above is arranged in the tower body 3, and the tower body 3 further has a liquid pump 32 in communication with the slurry pool 31, and the liquid pump 32 is in communication with the slurry inlet pipe 33. The slurry is pressurized by the liquid pump 32, flows through the slurry inlet pipe 33 from the slurry pool 31, enters the annular cavity in the base 1, and is sprayed out by the first nozzle 11 and the second nozzle 12 to perform the spraying work on the flue gas. The sprayed limestone slurry can absorb the sulfur dioxide in the flue gas to achieve the purpose of desulfurization of the flue gas.

[0056] In addition, the tower body 3 has a flue gas inlet 4, as shown in Figure 7 , Figure 8As shown, the spray mechanism is arranged on the tower body 3 and communicates with the inside of the tower body 3 and is below the flue gas outlet 5. In some embodiments of the present application, the flue gas enters through the flue gas inlet 4, is fully contacted with the limestone slurry by the spray of the spray mechanism, and is discharged through the flue gas outlet 5 to achieve the purpose of desulfurization.

[0057] In some embodiments of the present application, the desulfurization tower further comprises a demister 6 and a guide plate 7, as shown in Figure 8 As shown, the demister 6 is arranged above the spray mechanism. When the flue gas passes through the spray of the spray mechanism, the limestone slurry that may be entrained in the flue gas is contacted with the demister 6, so that the limestone slurry stays on the surface of the demister 6 and flows into the slurry pool 31; the guide plate 7 is fixedly arranged inside the tower body 3 and is inclined, and is used for guiding the treated flue gas to the flue gas outlet 5. After the flue gas is contacted with the demister 6, the final clean gas is discharged from the flue gas outlet 5 above along the inclined surface of the guide plate 7.

[0058] In the embodiments of the present application, the demister 6 is movably connected with the tower body 3 in the height direction, and a trigger switch is arranged at the top or bottom of the demister 6. When the flue gas concentration is large, the water content attached to the demister 6 increases, which causes the demister 6 to descend. When the demister 6 descends to a set position and contacts the trigger switch, the trigger switch controls the motor for driving the gear ring 21 to rotate in a direction of increasing the flow of the second nozzle 12, and vice versa. The trigger switch reversely rotates by a set angle. Through the above arrangement, the flow of the second nozzle 12 is self-adaptively adjusted according to the flow of the flue gas, so that the effect of flue gas treatment is improved and energy waste is reduced.

[0059] In some embodiments of the present application, the flue gas inlet 4 and the flue gas outlet 5 each comprise a bellows 5a communicating with the tower body 3 at one end, and a positioning block 5b fixedly arranged at the other end of the bellows 5a. The tower body 3 has a fixed plate 5c extending to the outside of the positioning block 5b, and the fixed plate 5c is provided with a positioning arc groove 5d. The positioning block 5b extends into the positioning arc groove 5d and is positioned at any position in the positioning arc groove 5d by a fastener. Figure 8As shown, one end of the flue gas inlet and outlet communicates with the bellows 5a, which can be adjusted according to the position of the external pipeline to change the direction of the flue gas inlet and outlet. In some embodiments of the present application, the fixed plate 5c is also oppositely arranged, and the fixed plate 5c is provided with a positioning arc groove 5d, which is matched with the positioning block 5b, and the positioning block 5b extends into the positioning arc groove 5d. It should be pointed out here that in the embodiments of the present application, the position where the fixed plate 5c is connected with the tower body 3 can be arranged in correspondence with up and down, left and right, or other directions. It should also be pointed out that in the embodiments of the present application, the connection mode of the positioning block 5b and the bellows 5a and the connection mode of the fixed plate 5c and the tower body 3 also have various forms, which can be various connection modes such as welding, riveting or screwing. The positioning block 5b extends into the positioning arc groove 5d and is positioned at any position in the positioning arc groove 5d by a fastener. It should be pointed out here that the fastener has various structural forms, for example, it can be in the form of a pin as shown in the middle, or it can be a screw, a rivet or a protruding structure provided on the adjusting slider. When the flue gas inlet and outlet are connected with the external pipeline, the direction of the bellows 5a is adjusted to facilitate flexible installation with the external pipeline. Figure 5

[0060] Those skilled in the art should understand that the present application is not limited by the above embodiments, and the above embodiments and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.​

Claims

1. A spraying mechanism, characterized in that, include: The base has an annular cavity inside, which is connected to an external slurry inlet pipe; Multiple first nozzles are fixed on the base. Each first nozzle includes a liquid inlet seat communicating with the annular cavity, a liquid inlet plate communicating with the liquid inlet seat, and multiple spray ports disposed on the liquid inlet plate and communicating with the interior of the liquid inlet plate. The liquid inlet seat has a spiral plate, the axial direction of which is parallel to the liquid inlet direction of the liquid inlet seat, and the liquid inlet plate has a cylindrical cavity. The base has two parallel mounting surfaces, and multiple first nozzles are mounted on one of the mounting surfaces. The other mounting surface also has multiple second nozzles, and the spray flow rate of the second nozzles can be adjusted. The second nozzle includes a fixed tube, a stop block, a drive disc, and a nozzle head. The nozzle head is connected to the fixed tube, and the drive disc is rotatably disposed between the two. The fixed tube has a sliding groove that is equally spaced toward the center at its end. The stop block is adapted to the sliding groove and can be moved relative to it within the sliding groove. The drive plate has an arc-shaped groove that is inclined toward the center. The stop block has a connecting post that extends into the arc-shaped groove. Multiple second nozzles are arranged in a circle on the base, the diameter of the drive disk is larger than that of the nozzle, and teeth are evenly distributed on the outer periphery of the drive disk; It also includes a drive mechanism for driving the multiple second nozzles to move synchronously; The drive mechanism includes a gear ring that meshes with the drive discs on a plurality of second nozzles, and also includes a drive member for driving the gear ring to rotate.

2. The spraying mechanism according to claim 1, characterized in that, The liquid inlet seat is frustum-shaped, and its cross-sectional diameter gradually decreases in the direction away from the base.

3. The spraying mechanism according to claim 1, characterized in that, The spray nozzle is in the shape of a conical tube.

4. The spraying mechanism according to claim 1, characterized in that, The driving component includes a gear, which is driven manually or by a motor.

5. A desulfurization tower, characterized in that, include: The tower body has a slurry pool at its bottom; The spraying mechanism as described in claim 4 is disposed in the tower body, and the tower body is further provided with a liquid pump communicating with the slurry tank, the liquid pump being connected to the slurry inlet pipeline; The flue gas inlet is located on the tower body, communicates with the interior of the tower body, and is situated below the spraying mechanism. The flue gas outlet is located on the tower body, communicating with the interior of the tower body and situated above the spraying mechanism.

6. The desulfurization tower according to claim 5, characterized in that, The desulfurization tower also includes: A demister is disposed above the spraying mechanism; A guide plate, which is fixed at an angle inside the tower body, is used to guide the treated flue gas to the flue gas outlet.

7. The desulfurization tower according to claim 6, characterized in that, Both the flue gas inlet and the flue gas outlet include a corrugated pipe with one end connected to the tower body. A positioning block is fixedly installed on the periphery of the other end of the corrugated pipe. The tower body has a fixing plate extending to the outside of the positioning block. A positioning arc groove is opened on the fixing plate. The positioning block extends into the positioning arc groove and is positioned at any position in the positioning arc groove by fasteners.

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