Microbial activation fermentation tank for selenium-rich earthworm manure

Abstract

The utility model discloses selenium -enriched earthworm manure microbial activation fermentation tank, including the jar body, the detachable connection of jar body top has the sealing tank cover, the surface of sealing tank cover is passed through and is opened the mounting hole, one end of stirring shaft is rotatably installed in the mounting hole, the other end of stirring shaft extends to the jar body inside and detachably connected with a plurality of variable diameter stirring vane subassembly on stirring shaft, the top surface fixed mounting of sealing tank cover has the drive motor, drive motor output shaft one end and stirring shaft one end fixed connection, through the flexible adjustment stirring radius of stirring vane subassembly before stirring fermentation operation, can according to the material characteristic (such as humidity, particle size) of different batches earthworm manure and the fermentation target (such as selenium element conversion rate requirement), the stirring effect of pertinence optimization, improve the adaptability of fermentation tank to different working conditions, ensure selenium source, fungicide and earthworm manure fully mix, promote selenium -enriched earthworm manure's quality and output.

Description

Technical Field

[0001] This utility model relates to the field of agricultural production, and more specifically, to a selenium-enriched earthworm castings microbial activation fermentation tank. Background Technology

[0002] In agricultural production, selenium-enriched earthworm castings, as a high-quality organic fertilizer, play a significant role in improving crop yield and quality due to their rich selenium content and abundance of beneficial microorganisms. Traditional earthworm casting fermentation tanks typically employ fixed-size stirring devices during the microbial activation fermentation of selenium-enriched earthworm castings. However, the characteristics of earthworm castings from different batches (such as moisture content and particle size) vary, and different fermentation goals (such as selenium conversion rate requirements) also necessitate different stirring effects. Existing fixed-size stirring devices cannot flexibly adjust the stirring range and intensity according to actual conditions. For earthworm castings with high moisture content and a tendency to clump, a fixed stirring radius may not be sufficient to break up clumps, resulting in insufficient material dispersion, affecting the contact between microorganisms and materials, and reducing fermentation efficiency. Furthermore, for fermentation processes requiring high mixing uniformity, a fixed stirring method may not achieve sufficient mixing of the selenium source, inoculants, and earthworm castings, thus affecting the quality and yield of the selenium-enriched earthworm castings.

[0003] How to invent a selenium-enriched earthworm castings microbial activation fermentation tank to improve these problems has become an urgent issue for those skilled in the art. Utility Model Content

[0004] To overcome the above shortcomings, this utility model provides a selenium-enriched earthworm castings microbial activation fermentation tank, which aims to improve the problem that the stirring device of the traditional fermentation tank cannot flexibly adapt to the different characteristics of earthworm castings and fermentation goals, resulting in low fermentation efficiency and affecting product quality and yield.

[0005] This invention is implemented as follows: a selenium-enriched earthworm castings microbial activation fermentation tank includes a tank body, a detachable sealing tank cover connected to the top of the tank body, a feed pipe connected to the sealing tank cover, a discharge pipe connected to the bottom of the tank body, a through-hole for mounting the surface of the sealing tank cover, one end of a stirring shaft rotatably mounted in the mounting hole, the other end of the stirring shaft extending into the tank body and detachably connected to several variable-diameter stirring blade assemblies, a drive motor fixedly mounted on the top surface of the sealing tank cover, one end of the output shaft of the drive motor fixedly connected to one end of the stirring shaft, each variable-diameter stirring blade assembly including a connecting sleeve, the connecting sleeve being detachably sleeved on the stirring shaft, several main stirring blades evenly distributed in a ring on the outer wall of the connecting sleeve, each main stirring blade having a cavity inside and an opening at the end away from the connecting sleeve, a secondary stirring blade slidably connected in each cavity, and each secondary stirring blade being connected to the connecting sleeve through a corresponding adjustment mechanism.

[0006] In a preferred embodiment of this utility model, the upper and lower ends of the connecting sleeve extend integrally to form a connecting part and an adjusting part, respectively. An adjusting ring is sleeved on the outside of the adjusting part. The adjusting ring can be independently displaced along the extending direction of the adjusting part. A connecting rod is hinged between the adjusting ring and the end of each auxiliary stirring blade.

[0007] In a preferred embodiment of this utility model, a connecting ring is coaxially arranged above the adjusting ring, and an annular slider is integrally arranged coaxially at the bottom of the connecting ring. The annular slider is slidably connected in an annular groove, which is coaxially formed on the upper surface of the adjusting ring. A plurality of first hinge seats, each corresponding to a secondary stirring blade, are integrally arranged on the upper surface of the connecting ring. A second hinge seat is integrally arranged on the bottom surface of the end of each secondary stirring blade away from the connecting sleeve. Both ends of each connecting rod are rotatably connected to two corresponding first hinge seats and second hinge seats, respectively.

[0008] In a preferred embodiment of this utility model, the outer wall of the adjusting part is provided with a connecting thread along its extension direction, and the inner wall of the adjusting ring is provided with a threaded groove corresponding to the connecting thread.

[0009] In a preferred embodiment of this utility model, the outer wall of the adjusting ring is integrally provided with a plurality of evenly distributed anti-slip textures.

[0010] In a preferred embodiment of this utility model, a plurality of annularly distributed connecting holes are provided through the outer wall of the connecting part, and a plurality of threaded holes are provided on the outer wall of the stirring shaft. The number and position of each set of threaded holes correspond one-to-one with the connecting holes on the connecting part, and fasteners are inserted into each corresponding threaded hole and connecting hole.

[0011] In a preferred embodiment of this utility model, multiple sets of threaded holes on the outer wall of the stirring shaft are distributed along the extension direction of the stirring shaft, and the number of sets is greater than the number of variable diameter stirring blade assemblies.

[0012] The beneficial effects of this utility model are as follows: The selenium-enriched earthworm castings microbial activation fermentation tank obtained by the above design can, during use, optimize the stirring effect in a targeted manner according to the material characteristics (such as humidity and particle size) and fermentation goals (such as selenium conversion rate requirements) of different batches of earthworm castings by flexibly adjusting the stirring radius of the stirring blade assembly before the stirring fermentation operation. This improves the adaptability of the fermentation tank to different working conditions, ensures that the selenium source, microbial agent and earthworm castings are fully mixed, and improves the quality and yield of selenium-enriched earthworm castings. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained from these drawings without creative effort.

[0014] Figure 1 This is a three-dimensional schematic diagram of the overall structure provided by the embodiment of this utility model.

[0015] Figure 2 A three-dimensional schematic view of the overall cross-sectional separation structure provided for an embodiment of this utility model.

[0016] Figure 3 A perspective view of the overall structure of the variable diameter stirring blade assembly provided for an embodiment of this utility model.

[0017] Figure 4 A three-dimensional schematic view of the cross-sectional structure of the variable diameter stirring blade assembly provided in this embodiment of the utility model.

[0018] Figure 5 A three-dimensional schematic view of the overall cross-sectional separation structure of the adjusting ring and connecting ring provided for an embodiment of this utility model.

[0019] In the diagram: 1-Tank body; 2-Agitator shaft; 101-Sealed tank cover; 102-Feed pipe; 103-Discharge pipe; 201-Drive motor; 202-Connecting sleeve; 203-Main agitator blade; 204-Cavity; 205-Secondary agitator blade; 206-Connecting part; 207-Adjusting part; 208-Adjusting ring; 209-Connecting rod; 210-Connecting hole; 211-Connecting ring; 212-Annular slider; 213-Annular groove; 214-Connecting thread; 215-Threaded groove; 216-First hinge seat; 217-Second hinge seat; 218-Anti-slip texture. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0021] Please see Figures 1 to 5This utility model provides a technical solution: a selenium-enriched earthworm castings microbial activation fermentation tank, including a tank body 1, a detachably connected sealing tank cover 101 at the top of the tank body 1, a feed pipe 102 connected to the sealing tank cover 101, a discharge pipe 103 connected to the bottom of the tank body 1, a through-hole for mounting the surface of the sealing tank cover 101, one end of a stirring shaft 2 rotatably mounted in the mounting hole, the other end of the stirring shaft 2 extending into the tank body 1, and several variable-diameter stirring blade assemblies detachably connected to the stirring shaft 2, and a drive motor 201 fixedly mounted on the top surface of the sealing tank cover 101. One end of the output shaft of the motor 201 is fixedly connected to one end of the stirring shaft 2. Each variable diameter stirring blade assembly includes a connecting sleeve 202, which is detachably sleeved on the stirring shaft 2. Several main stirring blades 203 are integrally arranged in a ring on the outer wall of the connecting sleeve 202. Each main stirring blade 203 has a cavity 204 inside and an opening of the cavity 204 at the end away from the connecting sleeve 202. A secondary stirring blade 205 is slidably connected in each cavity 204. Each secondary stirring blade 205 is connected to the connecting sleeve 202 through a corresponding adjustment mechanism.

[0022] Please see Figures 2 to 5 The connecting sleeve 202 extends integrally from the upper and lower ends to form a connecting part 206 and an adjusting part 207, respectively. An adjusting ring 208 is sleeved on the outside of the adjusting part 207. The adjusting ring 208 can be independently displaced along the extension direction of the adjusting part 207. A connecting rod 209 is hinged between the adjusting ring 208 and the end of each auxiliary stirring blade 205.

[0023] The inner diameters of the connecting part 206, the adjusting part 207, and the connecting sleeve 202 are all consistent with the outer diameter of the stirring shaft 2. The adjusting part 207 is located below the connecting sleeve 202, and its outer diameter is smaller than that of the connecting sleeve 202. The adjusting ring 208 can move up and down along the axial direction of the adjusting part 207. One end of the connecting rod 209 is hinged to the adjusting ring 208, and the other end is hinged to the end of the auxiliary stirring blade 205. When the adjusting ring 208 moves upward, the connecting rod 209 pushes the auxiliary stirring blade 205 to slide outward toward the main stirring blade 203, increasing the stirring radius; conversely, when the adjusting ring 208 moves downward, the auxiliary stirring blade 205 slides inward toward the main stirring blade 203, decreasing the stirring radius. This allows the stirring radius of the stirring blade assembly to be flexibly adjusted before the stirring fermentation operation, meeting the needs of different selenium-enriched earthworm castings fermentation processes. In actual production, the characteristics of earthworm castings (such as moisture content and particle size) and fermentation targets (such as selenium conversion rate requirements) may differ between different batches. By adjusting the position of the auxiliary stirring blade 205 during installation, the stirring effect can be optimized in a targeted manner. For example, for earthworm castings with high moisture content and a tendency to clump, the stirring radius can be increased to ensure that the material is fully dispersed; for fermentation processes that require high mixing uniformity, an appropriate stirring radius can be selected to ensure that the selenium source, inoculant, and earthworm castings are thoroughly mixed. This adjustment method improves the adaptability of the fermenter to different operating conditions, enhances the quality and yield of selenium-enriched earthworm castings, and at the same time, its simple and reliable structure reduces equipment maintenance costs.

[0024] Furthermore, a connecting ring 211 is coaxially arranged above the adjusting ring 208, and an annular slider 212 is integrally arranged coaxially at the bottom of the connecting ring 211. The annular slider 212 is slidably connected in an annular groove 213, which is coaxially opened on the upper surface of the adjusting ring 208. A number of first hinge seats 216 corresponding one-to-one with the auxiliary stirring blades 205 are integrally arranged on the upper surface of the connecting ring 211. A second hinge seat 217 is integrally arranged on the bottom surface of the end of each auxiliary stirring blade 205 away from the connecting sleeve 202. The two ends of each connecting rod 209 are rotatably connected to two corresponding first hinge seats 216 and second hinge seats 217 respectively.

[0025] The connecting ring 211 has an annular structure, with its inner diameter slightly larger than the outer diameter of the adjusting part 207. It is fitted around the outside of the adjusting part 207 and located above the adjusting ring 208. An annular slider 212 is integrally formed at the bottom of the connecting ring 211. The size of the annular slider 212 matches that of the annular groove 213, ensuring that the annular slider 212 can slide flexibly within the annular groove 213. The annular groove 213 is formed on the upper surface of the adjusting ring 208 and is distributed along the circumference of the adjusting ring 208. First hinge seats 216 are evenly distributed on the upper surface of the connecting ring 211, their number and position corresponding one-to-one with the auxiliary stirring blades 205. Second hinge seats 217 are located at the bottom of the auxiliary stirring blade 205 at the end furthest from the connecting sleeve 202. The two ends of the connecting rod 209 are hinged to the first hinge seats 216 and the second hinge seats 217 respectively via pins, forming a rotatable connection. When adjusting the position of the auxiliary stirring blade 205, the adjusting ring 208 is rotated, and the annular slider 212 slides within the annular groove 213, allowing the connecting ring 211 to move smoothly with the adjusting ring 208. This ensures that the connecting rod 209 drives the auxiliary stirring blade 205 to move accurately to the predetermined position and remains stable after fixing. This improves the stability and reliability of the adjustment process of the auxiliary stirring blade 205, thereby ensuring the accuracy of the fixed specifications of the stirring blade assembly. When installing and adjusting the stirring blade assembly, the characteristics of selenium-rich earthworm castings may cause significant resistance and vibration during the stirring process. If the connection structure is unstable, it can easily lead to inaccurate adjustment or loosening of the position of the auxiliary stirring blade 205. The cooperation between the annular slider 212 and the annular groove 213 restricts the radial movement of the connecting ring 211, ensuring that the connecting rod 209 always remains within the correct plane of motion, preventing the auxiliary stirring blade 205 from becoming skewed or jammed due to uneven force. This not only ensures the accuracy of the mixing radius after the mixing blade assembly is installed, but also enhances the structural strength of the mixing blade assembly, extends its service life, reduces the probability of equipment failure caused by problems with the mixing blade assembly, improves the continuity and stability of the selenium-enriched earthworm castings fermentation process, and thus improves product quality and production efficiency.

[0026] Furthermore, the outer wall of the adjusting part 207 is provided with a connecting thread 214 along its extension direction, and the inner wall of the adjusting ring 208 is provided with a threaded groove 215 corresponding to the connecting thread 214.

[0027] A connecting thread 214 is machined on the outer wall of the adjusting part 207, and a matching threaded groove 215 is formed on the inner wall of the adjusting ring 208. By rotating the adjusting ring 208, its position on the adjusting part 207 can be adjusted, thereby controlling the extension length of the auxiliary stirring blade 205. For example, when it is necessary to increase the stirring radius, rotating the adjusting ring 208 clockwise moves it upward, pushing the auxiliary stirring blade 205 outward through the connecting rod 209; conversely, rotating the adjusting ring 208 counterclockwise moves it downward, and the auxiliary stirring blade 205 retracts inward. The threaded connection method has the characteristics of self-locking and high adjustment precision, enabling precise setting of the stirring radius of the stirring blade assembly during the installation stage. In the process of microbial activation fermentation of selenium-enriched earthworm castings, different fermentation processes and material characteristics require different stirring radii. Through threaded transmission, the operator can precisely control the displacement of the adjusting ring 208, thereby accurately adjusting the extension length of the auxiliary stirring blade 205 and achieving fine adjustment of the stirring radius. This precise adjustment better meets the needs of material mixing and microbial growth during the fermentation of selenium-enriched earthworm castings, improving fermentation efficiency and product quality. Meanwhile, the threaded connection structure is stable and reliable, able to withstand the large torque and vibration generated during stirring, ensuring that the adjusted stirring blade assembly will not loosen during long-term use, reducing the frequency of equipment maintenance and adjustment, and improving operational stability and production efficiency. Furthermore, this structure allows operators to quickly adjust the specifications of the stirring blade assembly according to different fermentation tasks, enhancing the equipment's versatility.

[0028] Furthermore, the outer wall of the adjusting ring 208 is integrally provided with several evenly distributed anti-slip textures 218.

[0029] The anti-slip texture 218 features alternating concave and convex stripes evenly distributed along the outer wall of the adjusting ring 208. When installing the adjusting impeller assembly, the operator holds the adjusting ring 208 with their fingers firmly against the anti-slip texture 218, applying rotational force to adjust the position of the adjusting ring 208. This allows for precise adjustment of the position of the auxiliary impeller 205, thereby determining the fixed stirring radius of the impeller assembly.

[0030] Furthermore, a number of annularly distributed connecting holes 210 are provided through the outer wall of the connecting part 206, and multiple sets of threaded holes are provided on the outer wall of the stirring shaft 2. The number and position of each set of threaded holes correspond one-to-one with the connecting holes 210 on the connecting part 206, and fasteners are inserted into each corresponding threaded hole and connecting hole 210.

[0031] The connecting part 206 is located above the connecting sleeve 202, and has several annularly distributed connecting holes 210 penetrating its outer wall. The number of connecting holes 210 is determined according to the size and load-bearing capacity of the mixing blade assembly, and can be set to 4-8. Multiple sets of threaded holes are opened on the outer wall of the mixing shaft 2, with the number and position of each set of threaded holes corresponding one-to-one with the connecting holes 210 on the connecting part 206. When installing the variable diameter mixing blade assembly, the connecting sleeve 202 is fitted onto the mixing shaft 2, aligning the connecting holes 210 on the connecting part 206 with the corresponding threaded holes on the mixing shaft 2. Then, fasteners (such as bolts) are inserted into the connecting holes 210 and threaded holes, and tightened with nuts to firmly fix the variable diameter mixing blade assembly onto the mixing shaft 2. When it is necessary to replace the mixing blade assembly with a different specification, simply unscrew the fasteners to remove the old mixing blade assembly and install the new assembly. During the fermentation process of selenium-enriched earthworm castings, different fermentation tasks have different requirements for the specifications of the mixing blade assembly, and the mixing blade assembly will frequently come into contact with the material, making it susceptible to wear and corrosion. The detachable design allows operators to quickly replace the mixing blade assembly with different specifications to meet diverse fermentation process requirements. When the mixing blade assembly is damaged, it can be quickly disassembled for repair or replacement, reducing equipment downtime and ensuring continuous production. The detachable structure also facilitates cleaning and disinfection of the mixing shaft 2 and the mixing blade assembly, ensuring the equipment's hygiene and meeting the hygiene standards for organic fertilizer production.

[0032] Furthermore, multiple sets of threaded holes on the outer wall of the stirring shaft 2 are distributed along the extension direction of the stirring shaft 2, and the number of sets is greater than the number of variable diameter stirring blade assemblies.

[0033] The stirring shaft 2 is a cylindrical structure with multiple sets of threaded holes evenly distributed along the axial direction on its outer wall. The specifications of the threaded holes match the connecting holes 210 on the connecting part 206. The number and position of each set of threaded holes correspond one-to-one with the connecting holes 210 on the connecting part 206. In practical applications, operators pre-select multiple variable-diameter stirring blade assemblies of different specifications based on the volume of the selenium-enriched earthworm manure fermentation tank, the characteristics of the material, and the fermentation process requirements. For example, for a large-capacity fermentation tank, 3-4 variable-diameter stirring blade assemblies of different specifications can be installed. The assembly with a smaller stirring radius and a larger blade density is installed at the lower part of the stirring shaft 2 to break up the material with severe agglomeration at the bottom; the assembly with a larger stirring radius and a larger blade area is installed at the upper part of the stirring shaft 2 to thoroughly mix the material at the top. During installation, the connecting sleeves 202 of each stirring blade assembly are sequentially fitted onto the stirring shaft 2, aligning the connecting holes 210 on the connecting part 206 with the corresponding threaded holes on the stirring shaft 2, and then fixed with fasteners. It can achieve layered and multi-zone mixing of materials in the tank, ensuring that materials in different locations can be fully stirred and mixed.

[0034] Working principle: Before fermentation, the operator, based on the material characteristics (humidity, particle size, etc.) of the selenium-enriched earthworm castings and the fermentation process requirements, rotates the adjusting ring 208. Utilizing the threaded transmission between the adjusting part 207 and the adjusting ring 208, the adjusting ring 208 moves axially along the adjusting part 207. This movement, via the connecting rod 209, drives the auxiliary stirring blade 205 to slide within the cavity 204 of the main stirring blade 203, thereby adjusting the stirring radius of the stirring blade assembly. After determining the specifications of the stirring blade assembly, it is fixed to the corresponding threaded hole on the stirring shaft 2 through the connecting hole 210 of the connecting part 206 using fasteners. During fermentation, the drive motor 201 drives the stirring shaft 2 and the stirring blade assembly to rotate, mixing the earthworm castings, selenium source, and microbial agents within the tank 1. During unloading, the material is discharged from the inclined discharge pipe 103.

[0035] It should be noted that the specific model and specifications of the drive motor 201 need to be selected and determined according to the actual specifications of the device. The specific selection calculation method adopts the existing technology in this field, so it will not be described in detail here.

[0036] The power supply and principle of the drive motor 201 are clear to those skilled in the art and will not be described in detail here.

[0037] The above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A selenium-enriched earthworm castings microbial activation fermentation tank, characterized in that, The device includes a tank body, a detachable sealing lid connected to the top of the tank body, a feed pipe connected to the sealing lid, and a discharge pipe connected to the bottom of the tank body. A mounting hole is formed through the surface of the sealing lid, and one end of a stirring shaft is rotatably mounted within the mounting hole. The other end of the stirring shaft extends into the tank body, and several variable-diameter stirring blade assemblies are detachably connected to the stirring shaft. A drive motor is fixedly mounted on the top surface of the sealing lid, and one end of the drive motor's output shaft is fixedly connected to one end of the stirring shaft. Each variable-diameter stirring blade assembly includes a connecting sleeve, which is detachably fitted onto the stirring shaft. Several main stirring blades are integrally formed in a ring and evenly distributed on the outer wall of the connecting sleeve. Each main stirring blade has a cavity inside, with an opening at the end furthest from the connecting sleeve. A secondary stirring blade is slidably connected within each cavity, and each secondary stirring blade is connected to the connecting sleeve via a corresponding adjustment mechanism.

2. The selenium-enriched earthworm castings microbial activation fermentation tank as described in claim 1, characterized in that: The connecting sleeve extends integrally from its upper and lower ends to form a connecting part and an adjusting part, respectively. An adjusting ring is fitted outside the adjusting part. The adjusting ring can be independently displaced along the extending direction of the adjusting part. A connecting rod is hinged between the adjusting ring and the end of each auxiliary stirring blade.

3. The selenium-enriched earthworm castings microbial activation fermentation tank as described in claim 2, characterized in that: A connecting ring is coaxially arranged above the adjusting ring, and an annular slider is integrally arranged coaxially at the bottom of the connecting ring. The annular slider is slidably connected in an annular groove, which is coaxially formed on the upper surface of the adjusting ring. A plurality of first hinge seats are integrally arranged on the upper surface of the connecting ring, with each number and position corresponding to a secondary stirring blade. A second hinge seat is integrally arranged on the bottom surface of each secondary stirring blade at the end away from the connecting sleeve. Both ends of each connecting rod are rotatably connected to two corresponding first hinge seats and second hinge seats, respectively.

4. The selenium-enriched earthworm castings microbial activation fermentation tank as described in claim 2, characterized in that: The outer wall of the adjusting part is provided with a connecting thread along its extension direction, and the inner wall of the adjusting ring is provided with a threaded groove corresponding to the connecting thread.

5. The selenium-enriched earthworm castings microbial activation fermentation tank as described in claim 2, characterized in that: The outer wall of the adjustment ring is integrally provided with several evenly distributed anti-slip textures.

6. The selenium-enriched earthworm castings microbial activation fermentation tank as described in claim 2, characterized in that: The outer wall of the connecting part is provided with a number of evenly distributed annular connecting holes, and the outer wall of the stirring shaft is provided with a number of threaded holes. The number and position of each set of threaded holes correspond one-to-one with the connecting holes on the connecting part, and fasteners are inserted into each corresponding threaded hole and connecting hole.

7. The selenium-enriched earthworm castings microbial activation fermentation tank as described in claim 6, characterized in that: Multiple sets of threaded holes are distributed along the extension direction of the stirring shaft on the outer wall of the stirring shaft, and the number of sets is greater than the number of variable diameter stirring blades.

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