CN215352078U - Beta-cyclodextrin multi-effect evaporation crystallization device - Google Patents

Abstract

The utility model discloses a beta-cyclodextrin multi-effect evaporation crystallization device, which relates to the technical field of beta-cyclodextrin production equipment and comprises supporting legs, a discharge hole and a shell, wherein the top end of each supporting leg is vertically provided with the shell, the discharge hole is arranged in the middle of the bottom end of the shell, an air inlet pipe is arranged in the middle of the upper end of one side of the shell, a feed inlet is arranged at one side, close to the air inlet pipe, of the top end of the shell, an exhaust pipe is arranged at one side, far away from the air inlet pipe, above the shell, a servo motor is arranged in the middle of the top end of the shell, the output end of the servo motor is vertically provided with a vertical rod extending into the shell through a rotating shaft, and stirring rods are arranged at the upper end and the lower end of two sides of the vertical rod. According to the utility model, the driving lever and the movable block are arranged, so that the blockage of the discharge port is avoided, the discharge rate of beta-cyclodextrin is increased, only one power source of the servo motor is needed, the cost caused by a plurality of power sources is reduced, and the environmental protection property of the device is improved.

Description

Beta-cyclodextrin multi-effect evaporation crystallization device

Technical Field

The utility model relates to the technical field of betacyclodextrin production equipment, in particular to a betacyclodextrin multi-effect evaporation crystallization device.

Background

Betacyclodextrin is white crystal or crystalline powder, and is largely used in various industries due to the characteristics, wherein the betacyclodextrin is usually subjected to an evaporation crystallization mode in the production process, and a continuous evaporation crystallization device is usually adopted to improve the efficiency, wherein the multiple-effect evaporation crystallization device is one of important units of the betacyclodextrin, but the existing betacyclodextrin multiple-effect evaporation crystallization device has certain defects.

Through the search, chinese patent No. CN212548382U, announcement day 2021, 02/19, discloses a multi-effect evaporative crystallization apparatus with anti-clogging function, wherein the disclosure provides that "a side wall scraping plate attached to the inner wall of the crystallization tank is installed on a first scraping support rod and a second scraping support rod in a staggered manner from top to bottom, a bottom scraping plate attached to the inner wall of the frustum structure is installed at the bottom of the first scraping support rod, a vertical discharging pipe is installed at the center of the bottom of the crystallization tank, a mounting plate fixedly connected to the support is installed at the outer side of the bottom of the discharging pipe, and a discharge port anti-clogging assembly is installed on the mounting plate", which can avoid the discharge port from clogging, but additionally needs a driving source, which causes higher cost and also increases energy loss.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide a beta-cyclodextrin multi-effect evaporation crystallization device to solve the problem that the anti-blocking mode proposed in the background technology is not environment-friendly enough.

In order to achieve the purpose, the utility model provides the following technical scheme: a beta-cyclodextrin multi-effect evaporation crystallization device comprises supporting legs, a discharge port and a shell, and further comprises a filtering structure for preventing materials from being discharged along with steam, a stirring structure for improving evaporation crystallization efficiency and an anti-blocking structure for preventing crystallization materials from being blocked;

the top ends of the supporting legs are vertically provided with a shell, a discharge hole is formed in the middle of the bottom end of the shell, and the anti-blocking structures are arranged at the upper ends of two sides of the discharge hole;

the middle position of the upper end of the front side of the shell is provided with a PLC (programmable logic controller), the middle position of the upper end of one side of the shell is provided with an air inlet pipe, one side of the top end of the shell, which is close to the air inlet pipe, is provided with a feed inlet, one side of the top end of the shell, which is far away from the air inlet pipe, is provided with an exhaust pipe, and the filtering structure is arranged at the top end of the shell, which is at one side of the exhaust pipe;

the utility model discloses a vertical pole on casing, including casing top, servo motor, the upper end of montant both sides and lower extreme, the upper end of montant both sides is installed the puddler, and stirs the structure setting inside montant casing all around, the servo motor is installed to the intermediate position department on casing top, and the servo motor output through the vertical montant of installing of pivot extend to the casing inside, the puddler is installed to the upper end and the lower extreme of montant both sides, and stirs the structure setting.

Preferably, prevent stifled structure including preventing stifled case, prevent stifled case and install in the upper end of discharge gate both sides, and prevent that stifled incasement portion keeps away from one side of discharge gate and install fixed magnet, the prevent stifled incasement portion sliding connection of fixed magnet one side has the nature board of falling T, and fall the stifled incasement portion of preventing of nature board one side and install movable magnet, fall T nature board another side and extend to the inside movable block of installing of discharge gate, and one side on movable block top installs the shifting block, the driving lever that extends to the inside upper end of discharge gate is installed to the montant bottom.

Preferably, filtration includes rose box, flabellum, scum board, filter screen, bull stick and exhaust hole, the rose box is installed on the casing top of blast pipe one side, and the inside angles such as top of rose box have seted up the exhaust hole, the vertical rotation in intermediate position department on the inside top of rose box is connected with the bull stick, and the upper end and the lower extreme on bull stick surface install the flabellum, the filter screen is installed to the inside lower extreme of rose box, and the bottom of bull stick runs through the filter screen and installs the scum board.

Preferably, the shape of the scraper plate and the filter screen is arc, and the coverage area of the cross section of the filter screen is equal to the area of the cross section of the filter box.

Preferably, mix the structure and include annular scraper blade, slide bar, fixed plate, external screw thread, slider, orifice plate and screw thread piece, angle such as fixed plate are installed at shells inner wall's upper end and lower extreme, and one side of fixed plate is vertical installs the slide bar, the sliding surface of slide bar is connected with the slider, and the slider keeps away from one side annular of montant and installs annular scraper blade, the intermediate position department on montant surface is provided with the external screw thread, and the surface threaded connection of external screw thread has the screw thread piece, the screw thread piece install all around with slider one side fixed connection's orifice plate.

Preferably, the two ends of the pore plate are respectively welded with one ends of the sliding block and the thread block to form an integrated structure, and four pore plates are distributed at equal angles.

Preferably, the shape of movable block is the triangle-shaped, and the movable block is around the vertical axis symmetric distribution of discharge gate.

Compared with the related technology, the beta-cyclodextrin multi-effect evaporation crystallization device provided by the utility model has the following beneficial effects:

1. the utility model provides an anti-blocking box, a deflector rod and a movable block, wherein the deflector rod is driven to rotate by the rotation of a vertical rod, the top end of one side of the deflector rod is impacted discontinuously, so that the deflector rod moves to drive the movable block to move, thereby the inverse T-shaped plate slides, the distance between the fixed magnet and the inverse T-shaped plate is changed, the magnetic repulsion force is increased, when the deflector rod rotates away, the repulsive force enables the inverted T-shaped plate to drive the movable block to restore the original position, and further, the movable block moves left and right, stirring the crystalline material in the discharge port to avoid the crystalline material from blocking the discharge port, improving the discharge rate, avoiding reducing the production efficiency of beta-cyclodextrin evaporation crystallization due to blocking, only one power source of the servo motor is needed, so that the cost caused by a plurality of power sources is reduced, the production cost is reduced, the environmental protection performance of the device is improved, and the problem that the driving source is additionally needed for blocking prevention is solved;

2. the utility model provides a filtering structure, a small amount of materials in steam are separated by utilizing an arc-shaped filter screen, the loss caused by material discharge is avoided, the completeness of evaporation crystallization is ensured, meanwhile, the impulse force of upward movement of the steam can enable fan blades to rotate to drive a rotating rod to rotate, then an arc-shaped slag scraping plate rotates to scrape the materials at the bottom end of the surface of the filter screen and drop the materials into a shell, the materials are prevented from being blocked, the steam discharge rate is reduced, the normal operation of the device is further influenced, and therefore the problem that the materials are easily mixed in the discharged air is solved;

3. the utility model provides a stirring structure, wherein a threaded block is driven to move by the operation of a vertical rod by utilizing the threaded fit between an external thread and the threaded block, a pore plate is driven to slide downwards, a sliding block is driven to slide to drive an annular scraper plate to move, after the vertical rod is driven to rotate backwards by the operation of a servo motor after the vertical rod is lowered to a certain distance, the annular scraper plate and the pore plate are driven to move upwards, and then the raw materials are stirred in a secondary direction by the vertical movement of the annular scraper plate and the pore plate, so that the heating rate of the raw materials is higher, the evaporation effect is improved, the crystallization rate of the materials is ensured, the amount of crystals adhered to the inner wall of a shell can be reduced by the vertical movement of the annular scraper plate, the utilization rate of the raw materials is improved, the production benefit is further improved, and the problem of lower evaporation crystallization efficiency is solved.

Drawings

FIG. 1 is a schematic perspective view of the present invention;

FIG. 2 is a schematic front sectional view of the present invention;

FIG. 3 is a schematic side sectional view of the present invention;

FIG. 4 is a schematic top cross-sectional view of the present invention;

FIG. 5 is a schematic view of the exhaust pipe according to the present invention;

fig. 6 is a schematic structural view of the discharge port of the present invention.

In the figure: 1. a servo motor; 2. a feed inlet; 3. an air inlet pipe; 4. a PLC controller; 5. a support leg; 6. the anti-blocking box; 7. a discharge port; 8. a housing; 9. a filter structure; 901. a filter box; 902. a fan blade; 903. a slag scraping plate; 904. filtering with a screen; 905. a rotating rod; 906. an exhaust hole; 10. an exhaust pipe; 11. a stirring structure; 1101. an annular scraper; 1102. a slide bar; 1103. a fixing plate; 1104. an external thread; 1105. a slider; 1106. an orifice plate; 1107. a thread block; 12. a stirring rod; 13. a deflector rod; 14. a vertical rod; 15. shifting blocks; 16. fixing a magnet; 17. a movable block; 18. a reverse T-shaped plate; 19. a movable magnet.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1: referring to fig. 1-6, a beta-cyclodextrin multi-effect evaporation crystallization device comprises support legs 5, a discharge port 7 and a shell 8, and further comprises a filtering structure 9 for preventing materials from being discharged along with steam, a stirring structure 11 for improving evaporation crystallization efficiency and an anti-blocking structure for preventing crystallization materials from being blocked;

a shell 8 is vertically arranged at the top end of the supporting leg 5, a discharge hole 7 is arranged in the middle of the bottom end of the shell 8, and anti-blocking structures are arranged at the upper ends of two sides of the discharge hole 7;

a PLC (programmable logic controller) 4 is installed in the middle of the upper end of the front face of the shell 8, the type of the PLC 4 can be FX3SA-10MT-CM, an air inlet pipe 3 is installed in the middle of the upper end of one side of the shell 8, a feed inlet 2 is installed at one side, close to the air inlet pipe 3, of the top end of the shell 8, an exhaust pipe 10 is arranged at one side, far away from the air inlet pipe 3, of the upper portion of the shell 8, and a filtering structure 9 is arranged at the top end of the shell 8 at one side of the exhaust pipe 10;

a servo motor 1 is installed in the middle of the top end of the shell 8, the type of the servo motor 1 can be SGM7G-09AFC61, a vertical rod 14 extending into the shell 8 is vertically installed at the output end of the servo motor 1 through a rotating shaft, stirring rods 12 are installed at the upper end and the lower end of two sides of the vertical rod 14, and stirring structures 11 are arranged inside the shell 8 around the vertical rod 14;

referring to fig. 1-6, the anti-blocking structure comprises an anti-blocking box 6, the anti-blocking box 6 is mounted at the upper ends of the two sides of the discharge port 7, a fixed magnet 16 is mounted at one side, far away from the discharge port 7, inside the anti-blocking box 6 at one side of the fixed magnet 16, a reverse-T-shaped plate 18 is connected inside the anti-blocking box 6 at one side of the reverse-T-shaped plate 18 in a sliding manner, a movable magnet 19 is mounted inside the anti-blocking box 6 at one side of the reverse-T-shaped plate 18, the other side of the reverse-T-shaped plate 18 extends into the discharge port 7 and is provided with a movable block 17, a shifting block 15 is mounted at one side of the top end of the movable block 17, and a shifting lever 13 extending to the upper end inside the discharge port 7 is mounted at the bottom end of a vertical rod 14;

the movable block 17 is triangular, and the movable block 17 is symmetrically distributed about the vertical central axis of the discharge hole 7;

specifically, as shown in fig. 1, fig. 2, fig. 3 and fig. 6, the vertical rod 14 rotates to drive the shift lever 13 to rotate, intermittently impacts the top end of one side of the shift block 15, so that the shift block 15 moves to drive the movable block 17 to move, thereby causing the inverted T-shaped plate 18 to slide, changing the distance between the fixed magnet 16 and the inverted T-shaped plate 18, increasing the magnetic repulsive force, when the shift lever 13 is rotated away, the repulsive force causes the inverted T-shaped plate 18 to drive the movable block 17 to restore the original position, and further, by utilizing the left and right movement of the movable block 17, the crystallized materials in the discharge port 7 are stirred, the discharge port 7 is prevented from being blocked by the crystallized materials, only one power source of the servo motor 1 is needed, the cost caused by a plurality of power sources is reduced, simultaneously, the triangular movable block 17 improves the anti-blocking effect, reduces the amount of the crystallized materials accumulated on the top end of the movable block 17, and ensures the discharge amount of the crystallized materials.

Example 2: the filtering structure 9 comprises a filtering box 901, fan blades 902, a slag scraping plate 903, a filter screen 904, a rotating rod 905 and exhaust holes 906, the filtering box 901 is installed at the top end of the shell 8 on one side of the exhaust pipe 10, the exhaust holes 906 are formed in the top end of the inside of the filtering box 901 at equal angles, the rotating rod 905 is vertically and rotatably connected to the middle position of the top end of the inside of the filtering box 901, the fan blades 902 are installed at the upper end and the lower end of the surface of the rotating rod 905, the filter screen 904 is installed at the lower end of the inside of the filtering box 901, and the bottom end of the rotating rod 905 penetrates through the filter screen 904 and is provided with the slag scraping plate 903;

the shape of the slag scraping plate 903 and the filter screen 904 is arc, and the coverage area of the cross section of the filter screen 904 is equal to the area of the cross section of the filter box 901;

specifically, as shown in fig. 1, fig. 2 and fig. 5, utilize curved filter screen 904 to separate a small amount of material in the steam, the impulsive force that steam moved up simultaneously makes flabellum 902 rotate and drives the bull stick 905 and rotate, make curved scum board 903 rotate then and scrape the material of filter screen 904 surface bottom and drop to inside the casing 8, avoid the material to block up it, reduce steam discharge rate, and curved filter screen 904, the adhesion of reducible material is probably, further guarantee the discharge rate of steam.

Example 3: the stirring structure 11 comprises an annular scraping plate 1101, a sliding rod 1102, a fixing plate 1103, an external thread 1104, a sliding block 1105, a pore plate 1106 and a thread block 1107, wherein the fixing plate 1103 is installed at the upper end and the lower end of the inner wall of the shell 8 at equal angles, the sliding rod 1102 is vertically installed on one side of the fixing plate 1103, the sliding block 1105 is connected to the surface of the sliding rod 1102 in a sliding manner, the annular scraping plate 1101 is installed on one side, away from the vertical rod 14, of the sliding block 1105 in an annular manner, the external thread 1104 is arranged in the middle position of the surface of the vertical rod 14, the thread block 1107 is connected to the surface of the external thread 1104 in a threaded manner, and the pore plate 1106 fixedly connected to one side of the sliding block 1105 is installed around the thread block 1107;

two ends of the orifice plate 1106 are respectively welded with one end of the sliding block 1105 and one end of the thread block 1107 to form an integrated structure, and four orifice plates 1106 are distributed at equal angles;

specifically, as shown in fig. 2, fig. 3 and fig. 4, by using the thread fit between the external thread 1104 and the thread block 1107, the thread block 1107 is driven to move by the operation of the vertical rod 14, the orifice plate 1106 slides downwards, and then the sliding block 1105 slides to drive the annular scraper 1101 to move, after the vertical rod descends to a certain distance, the vertical rod 14 is driven to rotate reversely by the operation of the servo motor 1, so that the annular scraper 1101 and the orifice plate 1106 move upwards, and then the raw material is stirred in the secondary direction by the up-and-down movement of the two, so that the heating rate is higher, the evaporation effect is improved, and the up-and-down movement of the annular scraper 1101 can reduce the amount of crystal adhering to the inner wall of the shell 8, and the utilization rate of the raw material is improved.

The output end of the PLC 4 is electrically connected with the input end of the servo motor 1 through a lead.

The working principle is as follows: when the device is used, firstly, a betacyclodextrin raw material is injected into the shell 8 through the feeding hole 2, then the shell is externally connected with a power supply, hot steam is blown in through the air inlet pipe 3, meanwhile, the servo motor 1 is started to drive the vertical rod 14 to rotate, and further, the stirring rod 12 is driven to rotate, so that the raw material is stirred, the raw material is heated more uniformly and rapidly, and is boiled more quickly, and the evaporative crystallization treatment is facilitated;

the first innovation point implementation step:

the first step is as follows: meanwhile, the vertical rod 14 rotates, and by means of the threaded fit between the external threads 1104 and the threaded block 1107, the threaded block 1107 moves downwards to drive the orifice plate 1106 to slide downwards, so that the sliding block 1105 slides downwards on the surface of the sliding rod 1102 to drive the annular scraper 1101 to move;

the second step is that: when the temperature is reduced to a certain distance, the servo motor 1 works to drive the vertical rod 14 to rotate reversely, so that the annular scraping plate 1101 and the pore plate 1106 move upwards, and the raw materials are stirred in the secondary direction through the vertical movement of the annular scraping plate 1101 and the pore plate 1106, so that the heating rate is higher, and the evaporation effect is improved;

the third step: and the annular scraper 1101 moves up and down, so that the amount of crystals adhered to the inner wall of the shell 8 can be reduced, and the utilization rate of raw materials is improved.

The implementation step of the second innovation point:

the first step is as follows: the evaporated steam enters the filter box 901, and a small amount of materials in the steam are separated by an arc-shaped filter screen 904;

the second step is that: meanwhile, the impulse force of the upward movement of the steam can enable the fan blade 902 to rotate to drive the rotating rod 905 to rotate, and then the arc-shaped slag scraping plate 903 rotates to scrape the material at the bottom end of the surface of the filter screen 904 and drop the material into the shell 8, so that the material is prevented from being blocked, and the steam discharge rate is reduced;

the third step: the filtered steam enters the exhaust pipe 10 through the exhaust hole 906 and is conveyed to the next process step through the exhaust pipe 10, so that continuous evaporation and crystallization operation is realized.

The third innovation point implementation step:

the first step is as follows: after evaporation is finished, the discharge hole 7 is opened for discharging, meanwhile, the servo motor 1 is continuously started to enable the vertical rod 14 to rotate, further the driving lever 13 is driven to rotate, the top end of one side of the shifting block 15 is intermittently impacted, the shifting block 15 is driven to move to drive the movable block 17 to move, further the inverted T-shaped plate 18 slides towards the fixed magnet 16 in the anti-blocking box 6, the distance between the fixed magnet 16 and the inverted T-shaped plate 18 is changed, and the magnetic repulsive force of the inverted T-shaped plate is increased;

the second step is that: when the deflector rod 13 rotates away, the repulsive force enables the inverted T-shaped plate 18 to drive the movable block 17 to restore the original position, and further, the crystalline material in the discharge port 7 is stirred by utilizing the left-right movement of the movable block 17, so that the crystalline material is prevented from blocking the discharge port 7, and the discharge rate is improved;

the third step: and only one power source of the servo motor 1 is needed, so that the cost brought by a plurality of power sources is reduced.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the utility model, the scope of which is defined in the appended claims and their equivalents.

Claims (7)

1. The utility model provides a beta cyclodextrin multiple effect evaporation crystallization device, includes landing leg (5), discharge gate (7) and casing (8), its characterized in that: the device also comprises a filtering structure (9) for preventing the materials from being discharged along with the steam, a stirring structure (11) for improving the evaporation crystallization efficiency and an anti-blocking structure for preventing the crystallization materials from being blocked;

a shell (8) is vertically installed at the top end of the supporting leg (5), a discharge hole (7) is installed in the middle of the bottom end of the shell (8), and the anti-blocking structure is arranged at the upper ends of two sides of the discharge hole (7);

the PLC controller (4) is installed in the middle of the upper end of the front face of the shell (8), the air inlet pipe (3) is installed in the middle of the upper end of one side of the shell (8), the feed inlet (2) is installed on one side, close to the air inlet pipe (3), of the top end of the shell (8), the exhaust pipe (10) is arranged on one side, far away from the air inlet pipe (3), of the upper portion of the shell (8), and the filtering structure (9) is arranged on the top end of the shell (8) on one side of the exhaust pipe (10);

the utility model discloses a vertical bar (8) on casing (8) top, including casing (8), servo motor (1) and servo motor (1) output, the upper end of vertical bar (14) both sides is installed with the lower extreme and is stirred puddler (12), and mix structure (11) and set up inside vertical bar (14) casing (8) all around.

2. A beta-cyclodextrin multi-effect evaporation crystallization device according to claim 1, characterized in that: prevent stifled structure including preventing stifled case (6), prevent stifled case (6) and install the upper end in discharge gate (7) both sides, and prevent stifled case (6) inside one side of keeping away from discharge gate (7) and install fixed magnet (16), the inside sliding connection of preventing stifled case (6) of fixed magnet (16) one side has T nature board (18) of falling, and the stifled case (6) internally mounted who prevents in T nature board (18) one side has movable magnet (19), T nature board (18) another side of falling extends to discharge gate (7) inside and installs movable block (17), and one side on movable block (17) top installs shifting block (15), montant (14) bottom is installed and is extended to the inside driving lever (13) of discharge gate (7).

3. A beta-cyclodextrin multi-effect evaporation crystallization device according to claim 1, characterized in that: filtration (9) are including rose box (901), flabellum (902), scum board (903), filter screen (904), bull stick (905) and exhaust hole (906), install casing (8) top on blast pipe (10) one side rose box (901), and exhaust hole (906) have been seted up to the top of rose box (901) inside equiangular, the vertical rotation of intermediate position department on the inside top of rose box (901) is connected with bull stick (905), and upper end and the lower extreme on bull stick (905) surface install flabellum (902), filter screen (904) are installed to the inside lower extreme of rose box (901), and the bottom of bull stick (905) runs through filter screen (904) and install scum board (903).

4. A beta-cyclodextrin multi-effect evaporation crystallization device according to claim 3, characterized in that: the shape of the slag scraping plate (903) and the shape of the filter screen (904) are arc, and the coverage area of the cross section of the filter screen (904) is equal to the area of the cross section of the filter box (901).

5. A beta-cyclodextrin multi-effect evaporation crystallization device according to claim 1, characterized in that: mix structure (11) and include annular scraper blade (1101), slide bar (1102), fixed plate (1103), external screw thread (1104), slider (1105), orifice plate (1106) and screw block (1107), angle such as fixed plate (1103) are installed at the upper end and the lower extreme of casing (8) inner wall, and one side of fixed plate (1103) is vertical installs slide bar (1102), the surperficial sliding connection of slide bar (1102) has slider (1105), and slider (1105) keep away from one side annular of montant (14) and install annular scraper blade (1101), the intermediate position department on montant (14) surface is provided with external screw thread (1104), and the surperficial threaded connection of external screw thread (1104) has screw block (1107), screw block (1107) install all around with slider (1105) one side fixed connection's orifice plate (1106).

6. The beta-cyclodextrin multi-effect evaporation crystallization device as claimed in claim 5, wherein: the two ends of the pore plate (1106) are respectively welded with one ends of the sliding block (1105) and the thread block (1107) to form an integrated structure, and four pore plates (1106) are distributed at equal angles.

7. A beta-cyclodextrin multi-effect evaporation crystallization device according to claim 2, characterized in that: the movable block (17) is triangular, and the movable block (17) is symmetrically distributed around the vertical central axis of the discharge hole (7).

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