Preparation method of bamboo leaf powder

Abstract

The invention discloses a bamboo leaf powder preparation method, and relates to the technical field of bamboo leaf powder preparation.The bamboo leaf powder preparation method comprises the following steps that firstly, collected bamboo leaves are put into a cleaning device to be cleaned and aired, the purity and dryness of raw materials are ensured, and the bamboo leaves are put into a constant-temperature drying device to be dried during drying; the moisture content is reduced to be less than 10%; 2, the cleaned and aired bamboo leaves are put into a smashing device to be smashed; 3, the smashed bamboo leaf powder is put into a screening device to be screened, impurities are removed, and during screening, the bamboo leaf powder needs to be screened through a 40-80-mesh screen to ensure that the granularity of the bamboo leaf powder is uniform; 4, the screened bamboo leaf powder is placed in a reaction container, a solubilizer and a solvent are added, and the problems that in the prior art, when the bamboo leaf powder is prepared, the dispersity and solubility of an extract are poor, the using and adding effect of the extract is affected, and therefore the utilization rate of the extract is affected are solved.

Description

Technical Field

[0001] The invention relates to the technical field of bamboo leaf powder preparation, in particular to a method for preparing bamboo leaf powder. Background Art

[0002] Bamboo leaf powder is a powder made from processed bamboo leaves. This powder can be used as a food raw material and is widely used in various foods. The first local food safety standard for bamboo leaf powder in China clarifies the definition of bamboo leaf powder and its application standards as a common food raw material. After investigation, discussion, toxicological safety evaluation and sample analysis and testing, the standard finally determined the content standards of protein and dietary fiber in bamboo leaf powder, providing a scientific basis for the widespread application of bamboo leaf powder. In addition, bamboo leaf powder also has a high protein content and rich dietary fiber. These nutrients make bamboo leaf powder a food raw material and additive with potential health benefits.

[0003] For example, the Chinese authorized patent with announcement number CN107952095A (a method for preparing bamboo leaf powder for deodorization): comprising the following steps: placing fresh bamboo leaves in a sodium sulfate solution with a mass fraction of 2%-3% and soaking for 4-5 hours; taking out the soaked bamboo leaves, draining the water, and steaming them with water vapor containing sulfur dioxide at a temperature of 130-150°C for 25-30 minutes; placing the steamed bamboo leaves at a temperature of 70-80°C to dry, and crushing them to obtain bamboo leaf powder. The method for preparing bamboo leaf powder for deodorization provided by the present invention has a simple process and is easy to operate; the bamboo leaf powder prepared by the method provided by the present invention can effectively reduce the release of malodorous gases and is safe and harmless to the human body and the environment.

[0004] However, the dispersibility and solubility of the extract of bamboo leaf powder in the above-mentioned prior art are poor, which affects the effect of its use and addition, thereby affecting its utilization rate; therefore, it does not meet the existing needs, and we propose a method for preparing bamboo leaf powder. Summary of the invention

[0005] The object of the present invention is to provide a method for preparing bamboo leaf powder, so as to solve the problem that the dispersibility and solubility of the extract of bamboo leaf powder in the prior art proposed in the above background technology are poor when preparing the bamboo leaf powder, which affects the effect of its use and addition, thereby affecting its utilization rate.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for preparing bamboo leaf powder, comprising the following steps:

[0007] Step 1: First, the collected bamboo leaves are placed in a cleaning device for cleaning and drying to ensure the purity and dryness of the raw materials. This step is to remove dirt and moisture from the raw materials to ensure the quality of subsequent processing. When drying, they are placed in a constant temperature drying device to reduce the moisture content to less than 10%. The purpose of this step is to prevent the bamboo leaves from mold or deterioration during subsequent processing, and it also helps to improve the quality of bamboo leaf powder;

[0008] Step 2: The washed and dried bamboo leaves are placed in a crushing device for crushing and ground into powder by mechanical or physical methods. This step is the key to preparing bamboo leaf powder. The crushing allows the raw materials to reach the required fineness for subsequent processing and use.

[0009] Step 3: Put the crushed bamboo leaf powder into a screening device for screening to remove impurities. The screening is to further purify the powder to ensure the purity of the final product. During the screening, the bamboo leaf powder needs to be screened through a 40-80 mesh screen to ensure that the particle size of the bamboo leaf powder is uniform and meets the use requirements;

[0010] Step 4: Place the sieved bamboo leaf powder in a reaction container, add a solubilizer and a solvent, and extract at 20-60°C for 3-6 hours. The purpose of this step is to improve the extraction efficiency of the effective ingredients in the bamboo leaves so that the effective ingredients in the bamboo leaf powder can be better utilized. The powder is then packaged to obtain finished bamboo leaf powder, and the packaging is for the convenience of storage and transportation.

[0011] Preferably, based on the devices in steps one to four, the cleaning device and drying device in step one include a cleaning seat and a drying box, the crushing device in step two includes a crushing box, the screening device in step three includes a screening box, and the reaction container in step four includes a reaction tank.

[0012] Preferably, a cleaning chamber is provided inside the cleaning seat, a drying box is provided on one side of the upper surface of the cleaning seat, a support frame is provided above the cleaning chamber, and a movable groove is provided inside the support frame.

[0013] Preferably, a movable seat is installed inside the movable groove, and the movable seat is slidably connected inside the movable groove. A mounting frame is provided below the movable seat, a telescopic rod is provided at the bottom of the mounting frame, and a cleaning roller is installed at the bottom of the telescopic rod.

[0014] Preferably, a spray plate is provided at the bottom end of the cleaning chamber, and a spray head is provided on the upper surface of the spray plate, and a plurality of the spray heads are provided.

[0015] Preferably, both inner walls of the cleaning chamber are provided with lifting grooves, a mounting seat is installed inside the lifting grooves, a cleaning frame is provided inside the cleaning chamber, both side end faces of the cleaning frame are provided with connecting blocks, and the connecting blocks are plug-connected with the inside of the mounting seat.

[0016] Preferably, a first support seat is provided on one side of the screening box, a crushing box is provided above the first support seat, a feed plate is provided on one side of the crushing box, a push plate is provided on one side inside the feed plate, and a cylinder is installed on one end face of the feed plate.

[0017] Preferably, a vibration motor is provided on the front end face of the screening box, a discharge port is provided on the other end face of the screening box, a screening plate is installed inside the screening box, a partition is installed inside the crushing box, drive shafts are provided on both sides of the partition, and crushing blades are installed around the drive shaft.

[0018] Preferably, a second support seat is provided at the bottom of the reaction tank, support feet are provided at the bottom of the first support seat and the second support seat, a control device is provided at the front end surface of the second support seat, a sealing cover is provided at the top of the reaction tank, and feed pipes are provided on both sides of the upper surface of the sealing cover.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention provides a reaction tank, places the sieved bamboo leaf powder in the reaction tank, adds a solubilizing agent and a solvent, and extracts for 3 to 6 hours at 20 to 60° C. The purpose of this step is to improve the extraction efficiency of the effective ingredients in the bamboo leaves so that the effective ingredients in the bamboo leaf powder can be better utilized. The solubilizing agent mainly includes polysorbates and polyoxyethylene fatty acid esters. By adding an appropriate amount of the solubilizing agent, not only the solubility and dispersibility of the bamboo leaf powder in water can be improved, but also the application effect thereof as a nutritional supplement can be improved, especially in improving the absorption and utilization of the effective ingredients in the bamboo leaf powder. The mechanism of action of the solubilizing agent is mainly that they can form micelles in water, and these micelles can contain or adsorb insoluble substances, thereby increasing the amount of the solubilizing agent in the solution, thereby solving the problem that the dispersibility and solubility of the extract of the bamboo leaf powder in the prior art are poor, which affects the effect of the extract when the extract is added, thereby affecting the utilization rate of the extract.

[0021] 2. By arranging a spray plate and a spray head inside the cleaning bin, the cleaning frame is plugged and connected to the mounting seat through a connecting block and fixed with screws, the bamboo leaves are placed inside the cleaning frame, and the mounting seat is moved inside the lifting tank to sink the bamboo leaves into the water inside the cleaning bin. The spray plate and the spray head are used to accelerate the flow of water, and the moving seat is moved laterally inside the moving tank. At the same time, the telescopic rod at the bottom of the mounting frame makes the cleaning roller descend to the inside of the cleaning frame. The cleaning operation is performed together with the rotation of the cleaning roller, which can better remove dirt on the raw materials to ensure the quality of subsequent processing.

[0022] 3. By setting a crushing box on one side of the screening box, the cleaned and dried bamboo leaves are placed inside the feed plate. During feeding, the cylinder drives the push plate to push the bamboo leaves into the crushing box to ensure the safety of operation. Then the two sets of drive shafts inside the crushing box drive the crushing blades to rotate and crush, and then enter the screening box through the connecting port. The three sets of screening plates set inside the screening box are placed in order from large to small density, and the vibration motor drives them to vibrate to play a screening role, which is convenient and fast. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the overall structure of the bamboo leaf washing and drying device of the present invention;

[0024] Figure 2 It is an enlarged schematic diagram of the local structure inside the cleaning seat of the present invention;

[0025] Figure 3 It is an enlarged schematic diagram of the local structure of the cleaning frame of the present invention;

[0026] Figure 4 It is a schematic diagram of the structure of the bamboo leaf crushing and screening device of the present invention;

[0027] Figure 5 It is an enlarged schematic diagram of the local structure inside the crushing box of the present invention;

[0028] Figure 6 This is a schematic diagram of the structure of the bamboo leaf powder reaction tank of the present invention;

[0029] In the figure: 1. cleaning seat; 2. cleaning chamber; 3. drying box; 4. supporting frame; 5. moving slot; 6. moving seat; 7. cleaning roller; 8. spray plate; 9. spray head; 10. lifting slot; 11. mounting seat; 12. cleaning frame; 13. connecting block; 14. screening box; 15. first supporting seat; 16. crushing box; 17. feeding plate; 18. pushing plate; 19. cylinder; 20. vibration motor; 21. discharge port; 22. partition; 23. driving shaft; 24. crushing blade; 25. second supporting seat; 26. supporting foot; 27. control device; 28. reaction tank; 29. ​​sealing cover; 30. feeding pipe. DETAILED DESCRIPTION

[0030] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0031] See also Figure 1-6 The present invention provides an embodiment: a method for preparing bamboo leaf powder, comprising the following steps:

[0032] Step 1: First, the collected bamboo leaves are placed in a cleaning device for cleaning and drying to ensure the purity and dryness of the raw materials. This step is to remove dirt and moisture from the raw materials to ensure the quality of subsequent processing. When drying, they are placed in a constant temperature drying device to reduce the moisture content to less than 10%. The purpose of this step is to prevent the bamboo leaves from mold or deterioration during subsequent processing, and it also helps to improve the quality of bamboo leaf powder;

[0033] Step 2: The washed and dried bamboo leaves are placed in a crushing device for crushing and ground into powder by mechanical or physical methods. This step is the key to preparing bamboo leaf powder. The crushing allows the raw materials to reach the required fineness for subsequent processing and use.

[0034] Step 3: Put the crushed bamboo leaf powder into a screening device for screening to remove impurities. The screening is to further purify the powder and ensure the purity of the final product. During screening, the bamboo leaf powder needs to be screened through a 40-80 mesh screen to ensure that the particle size of the bamboo leaf powder is uniform and meets the use requirements;

[0035] Step 4: Place the sieved bamboo leaf powder in a reaction container, add a solubilizer and a solvent, and extract at 20-60°C for 3-6 hours. The purpose of this step is to improve the extraction efficiency of the effective ingredients in the bamboo leaves so that the effective ingredients in the bamboo leaf powder can be better utilized. Then package it to obtain the finished bamboo leaf powder, and the packaging is for the convenience of storage and transportation. The solubilizer mainly includes polysorbates and polyoxyethylene fatty acid esters. By adding an appropriate amount of solubilizer, not only the solubility and dispersibility of the bamboo leaf powder in water can be improved, but also it helps to improve its application effect as a nutritional supplement, especially in improving the absorption and utilization of the effective ingredients in the bamboo leaf powder. At the same time, the mechanism of action of the solubilizer is mainly that they can form micelles in water. These micelles can contain or adsorb insoluble substances, thereby increasing their solubility in the solution, solving the problem that the dispersibility and solubility of the extract of the bamboo leaf powder in the prior art are poor, affecting its effect when used and added, thereby affecting its utilization rate. By arranging a spray plate 8 and a spray head 9 inside the cleaning bin 2, the cleaning frame 12 is connected After the block 13 is plugged and connected with the mounting seat 11 and fixed with screws, the bamboo leaves are placed inside the cleaning frame 12, and the mounting seat 11 is moved inside the lifting groove 10 to sink the bamboo leaves into the water inside the cleaning bin 2, and the spray plate 8 and the spray head 9 are used to accelerate the flow of water. At the same time, the moving seat 6 moves horizontally inside the moving groove 5, and the telescopic rod at the bottom of the mounting frame makes the cleaning roller 7 descend to the inside of the cleaning frame 12. The cleaning operation is performed together with the rotation of the cleaning roller 7, which can better remove the dirt on the raw materials to ensure the quality of subsequent processing. The amount is obtained by setting a crushing box 16 on one side of the screening box 14, placing the cleaned and dried bamboo leaves inside the feeding plate 17, and during feeding, the cylinder 19 drives the pushing plate 18 to push the bamboo leaves into the crushing box 16, thereby ensuring the safety of operation. After that, the two sets of driving shafts 23 inside the crushing box 16 drive the crushing blades 24 to rotate and crush, and then enter the screening box 14 through the connecting port. The three sets of screening plates arranged inside the screening box 14 are placed in order from large to small density, and the vibration motor 20 drives them to vibrate to play a screening role, which is convenient and fast.

[0036] See also Figure 1-Figure 6 Based on the devices in steps one to four, the cleaning device and drying device in step one include a cleaning seat 1 and a drying box 3, the crushing device in step two includes a crushing box 16, the screening device in step three includes a screening box 14, and the reaction container in step four includes a reaction tank 28.

[0037] See also Figure 1-Figure 6A cleaning chamber 2 is arranged inside the cleaning seat 1, a drying box 3 is arranged on one side of the upper surface of the cleaning seat 1, a supporting frame 4 is arranged above the cleaning chamber 2, and a movable groove 5 is arranged inside the supporting frame 4. By arranging a spray plate 8 and a spray head 9 inside the cleaning chamber 2, the cleaning frame 12 is plugged and connected with the mounting seat 11 through a connecting block 13, and fixed with screws, the bamboo leaves are placed inside the cleaning frame 12, and the mounting seat 11 is moved in the lifting groove 10 to sink it into the water inside the cleaning chamber 2, and the spray plate 8 and the spray head 9 are used to accelerate the flow of water. At the same time, the movable seat 6 moves laterally inside the movable groove 5, and at the same time, the telescopic rod at the bottom of the mounting frame makes the cleaning roller 7 descend to the inside of the cleaning frame 12, and the cleaning operation is performed together with the rotation of the cleaning roller 7, which can better remove the dirt on the raw materials to ensure the quality of subsequent processing.

[0038] See also Figure 1-Figure 6 A moving seat 6 is installed inside the moving groove 5, and the moving seat 6 is slidably connected inside the moving groove 5. A mounting frame is arranged below the moving seat 6, and a telescopic rod is arranged at the bottom of the mounting frame, and a cleaning roller 7 is installed at the bottom of the telescopic rod.

[0039] See also Figure 1-Figure 6 A spray plate 8 is provided at the bottom end of the cleaning bin 2, and a spray head 9 is provided on the upper surface of the spray plate 8. Several spray heads 9 are provided. By arranging the spray plate 8 and the spray head 9 inside the cleaning bin 2, the cleaning frame 12 is plugged and connected with the mounting seat 11 through the connecting block 13, and fixed with screws, the bamboo leaves are placed inside the cleaning frame 12, and the mounting seat 11 is moved inside the lifting groove 10 to sink it into the water inside the cleaning bin 2, and the spray plate 8 and the spray head 9 are used to accelerate the flow of water. At the same time, the moving seat 6 moves laterally inside the moving groove 5, and at the same time, the telescopic rod at the bottom of the mounting frame makes the cleaning roller 7 descend to the inside of the cleaning frame 12, and the cleaning operation is performed together with the rotation of the cleaning roller 7, which can better remove the dirt on the raw materials to ensure the quality of subsequent processing.

[0040] See also Figure 1-Figure 6 The inner walls on both sides of the cleaning bin 2 are provided with lifting grooves 10, and mounting seats 11 are installed inside the lifting grooves 10. A cleaning frame 12 is arranged inside the cleaning bin 2, and connecting blocks 13 are arranged on the end faces on both sides of the cleaning frame 12. The connecting blocks 13 are plugged and connected with the mounting seats 11 to facilitate the lifting and lowering of the cleaning frame 12 and the taking and placing of the bamboo leaves. After cleaning, they are dried and placed in a constant temperature drying device to reduce the moisture content therein to below 10%. The purpose of this step is to prevent the bamboo leaves from becoming moldy or deteriorating during subsequent processing, and it also helps to improve the quality of bamboo leaf powder.

[0041] See also Figure 1-Figure 6A first supporting seat 15 is provided on one side of the screening box 14, a crushing box 16 is provided above the first supporting seat 15, a feeding plate 17 is provided on one side of the crushing box 16, a pushing plate 18 is provided on one side of the inside of the feeding plate 17, and a cylinder 19 is installed on one end surface of the feeding plate 17. The cleaned and dried bamboo leaves are placed inside the feeding plate 17. When feeding, the cylinder 19 drives the pushing plate 18 to push the bamboo leaves into the inside of the crushing box 16, thereby ensuring the safety of operation.

[0042] See also Figure 1-Figure 6 A vibration motor 20 is provided on the front end face of the screening box 14, a discharge port 21 is provided on the other side end face of the screening box 14, a screening plate is installed inside the screening box 14, and the crushed bamboo leaves enter the interior of the screening box 14 through the connecting port. The three groups of screening plates arranged inside the screening box 14 are arranged in descending order of density, and the vibration motor 20 drives it to vibrate to play a screening role, which is convenient and quick.

[0043] See also Figure 1-Figure 6 A partition 22 is installed inside the crushing box 16, and a driving shaft 23 is provided on both sides of the partition 22. Crushing blades 24 are installed around the driving shaft 23. The cleaned and dried bamboo leaves are placed inside the feeding plate 17. During feeding, the cylinder 19 drives the pushing plate 18 to push the bamboo leaves into the crushing box 16, ensuring the safety of operation. Then, the two sets of driving shafts 23 inside the crushing box 16 drive the crushing blades 24 to rotate and crush, and then enter the interior of the screening box 14 through the connecting port. The three sets of screening plates arranged inside the screening box 14 are placed in order from large to small density, and the vibration motor 20 drives it to vibrate to play a screening role, which is convenient and fast.

[0044] See also Figure 1-Figure 6A second support seat 25 is provided at the bottom of the reaction tank 28, support feet 26 are provided at the bottom of the first support seat 15 and the second support seat 25, a control device 27 is provided at the front end surface of the second support seat 25, a sealing cover 29 is provided at the top of the reaction tank 28, and feeding pipes 30 are provided on both sides of the upper surface of the sealing cover 29. The sieved bamboo leaf powder is placed in the reaction tank 28, a solubilizing agent and a solvent are added, and the extraction is carried out at 20 to 60°C for 3 to 6 hours. The purpose of this step is to improve the extraction efficiency of the effective ingredients in the bamboo leaves, so that the effective ingredients in the bamboo leaf powder can be better utilized, and then the finished bamboo leaf powder is packaged to obtain the finished bamboo leaf powder, and the packaging is for the convenience of storage and Transportation, solubilizers mainly include polysorbates and polyoxyethylene fatty acid esters. By adding an appropriate amount of solubilizer, not only the solubility and dispersibility of bamboo leaf powder in water can be improved, but also its application effect as a nutritional supplement can be improved, especially in improving the absorption and utilization of effective ingredients in bamboo leaf powder. At the same time, the mechanism of action of solubilizers is mainly that they can form micelles in water. These micelles can encapsulate or adsorb insoluble substances, thereby increasing their solubility in the solution, solving the problem that the dispersibility and solubility of the extract of bamboo leaf powder in the prior art are poor during preparation, affecting its effect when used and added, thereby affecting its utilization rate.

[0045] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

Claims

1. A method for preparing bamboo leaf powder, characterized in that: The following steps are involved: Step 1: First, the collected bamboo leaves are placed in a cleaning device for cleaning and drying to ensure the purity and dryness of the raw materials. When drying, they are placed in a constant temperature drying device to reduce the moisture content to less than 10%; Step 2: The washed and dried bamboo leaves are placed in a crushing device for crushing; Step 3: Put the crushed bamboo leaf powder into a screening device for screening to remove impurities. During screening, the bamboo leaf powder needs to be screened through a 40-80 mesh screen to ensure that the particle size of the bamboo leaf powder is uniform; Step 4: Place the sieved bamboo leaf powder in a reaction container, add a solubilizer and a solvent, extract at 20-60° C. for 3-6 hours, and finally package and transport.

2. The method for preparing bamboo leaf powder according to claim 1, based on the device in steps 1 to 4, is characterized in that: The cleaning device and drying device in step one include a cleaning seat (1) and a drying box (3), the crushing device in step two includes a crushing box (16), the screening device in step three includes a screening box (14), and the reaction container in step four includes a reaction tank (28).

3. The method for preparing bamboo leaf powder according to claim 2, characterized in that: A cleaning chamber (2) is arranged inside the cleaning seat (1), a drying box (3) is arranged on one side of the upper surface of the cleaning seat (1), a support frame (4) is arranged above the cleaning chamber (2), and a movable groove (5) is arranged inside the support frame (4).

4. The method for preparing bamboo leaf powder according to claim 3, characterized in that: A movable seat (6) is installed inside the movable groove (5), and the movable seat (6) is slidably connected inside the movable groove (5). A mounting frame is arranged below the movable seat (6), and a telescopic rod is arranged at the bottom of the mounting frame, and a cleaning roller (7) is installed at the bottom of the telescopic rod.

5. The method for preparing bamboo leaf powder according to claim 4, characterized in that: A spray plate (8) is arranged at the bottom end of the cleaning chamber (2), and a spray head (9) is arranged on the upper surface of the spray plate (8), wherein a plurality of spray heads (9) are arranged.

6. The method for preparing bamboo leaf powder according to claim 5, characterized in that: The inner walls on both sides of the cleaning chamber (2) are provided with lifting grooves (10), a mounting seat (11) is installed inside the lifting grooves (10), a cleaning frame (12) is provided inside the cleaning chamber (2), and the end surfaces on both sides of the cleaning frame (12) are provided with connecting blocks (13), and the connecting blocks (13) are plug-connected with the inside of the mounting seat (11).

7. The method for preparing bamboo leaf powder according to claim 6, characterized in that: A first support seat (15) is provided on one side of the screening box (14), a crushing box (16) is provided above the first support seat (15), a feed plate (17) is provided on one side of the crushing box (16), a push plate (18) is provided on one side inside the feed plate (17), and a cylinder (19) is installed on one end face of the feed plate (17).

8. The method for preparing bamboo leaf powder according to claim 7, characterized in that: A vibration motor (20) is arranged at the front end surface of the screening box (14), a discharge port (21) is arranged at the other end surface of the screening box (14), and a screening plate is installed inside the screening box (14).

9. The method for preparing bamboo leaf powder according to claim 8, characterized in that: A partition (22) is installed inside the crushing box (16), a driving shaft (23) is arranged on both sides of the partition (22), and crushing blades (24) are installed around the driving shaft (23).

10. The method for preparing bamboo leaf powder according to claim 9, characterized in that: A second support seat (25) is arranged at the bottom of the reaction tank (28), support feet (26) are arranged at the bottom of the first support seat (15) and the second support seat (25), a control device (27) is arranged at the front end surface of the second support seat (25), a sealing cover (29) is arranged at the top of the reaction tank (28), and feeding pipes (30) are arranged on both sides of the upper surface of the sealing cover (29).

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