Low-temperature liquid cooling micro-pulverizer and application thereof

Abstract

The invention provides a low-temperature liquid cooling micro-pulverizer which is provided with a feeding hopper, materials enter a pulverizing area through the feeding hopper, the pulverizing area is a cavity defined by an end cover, a rotating wheel and a stator, and a discharging opening is formed in the top of the end cover; the crushing area is of a vertical structure, and a grading wheel is arranged in the grading area. The invention further provides application of the low-temperature liquid cooling micro-pulverizer. According to the low-temperature liquid-cooled micro-pulverizer provided by the invention, the low-temperature micro-pulverizer for pulverizing peanut cakes is researched and designed aiming at the problems of material blockage and protein denaturation caused by temperature rise in a pulverizing cavity when a current pulverizer is used for pulverizing the peanut cakes, and an internal flow channel structure of the low-temperature liquid-cooled micro-pulverizer is determined. The problem of temperature rise caused by crushing is reduced during crushing, so that the oil penetration rate of peanut cake particles is reduced, material blockage is prevented, and meanwhile, protein denaturation is prevented.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of crushing, and particularly relates to a peanut cake crushing device and application thereof. BACKGROUND

[0002] As one of the eight major oil crops in China, the annual output of peanuts reaches 18.3 million tons, accounting for 1 / 3 of the world. Peanut cake is a by-product produced after the oil is extracted from peanut fruit. The protein content of the cake produced after pressing can reach 52-62%. More than 90% of the peanut oil is extracted by high-temperature pressing (above 150°C). Although high temperature can increase the oil extraction of the material, it causes the denaturation of the protein in the by-product peanut cake, resulting in resource waste when used as feed. The protein in the peanut cake produced by low-temperature pressing is highly active and functional, and has a broad application prospect, with a global scale of up to 27.6 billion US dollars and increasing year by year. Semi-depleted, low-temperature, fine-grained and full-nutrient peanut protein powder is increasingly popular as a natural food additive.

[0003] Although the protein activity of the peanut cake produced by low-temperature pressing can reach 50-60%, the oil content of the peanut cake is between 10% and 20%. During crushing, the particles in the cavity and at the inlet and outlet are prone to stick to the wall, causing blockage. Further temperature rise can cause the denaturation of peanut protein. Therefore, low-temperature crushing is designed to enhance the brittleness of food materials and reduce the increase in oil permeability caused by temperature rise, achieving efficient crushing.

[0004] The current peanut protein crushing fineness (mesh number) is generally above 124 μm. If the crushing fineness is reduced to below 75 μm, the blockage rate will increase significantly. The fineness of the powder is positively correlated with the absorption rate of protein by the human body, the water solubility of the powder, and the release rate of nutritional components. Therefore, how to reduce protein denaturation and improve functional properties such as foamability and emulsifiability affected by it during the crushing process with production efficiency is an important research topic. In addition, the particle size of the crushed product is smaller, which can be better applied in food and has stronger stability.

[0005] Low-temperature crushing technology is a high-efficiency material processing method combining low-temperature refrigeration technology and crushing technology, which can enhance the brittleness of food materials and reduce the oil permeability caused by temperature rise.

[0006] Currently, the temperature in the crushing cavity of the existing micro-crushing machine continues to rise during long-time crushing operation, and the highest temperature can reach 75°C or even higher. After the temperature rises, the protein in the powder is prone to denaturation, and the particle toughness increases, causing problems such as adhesion and blockage, which further adversely affect the crushing effect. The main reasons for the temperature rise are as follows: 1) During the crushing process, the rotating wheel rotating at high speed breaks the particles by impact. In this process, the kinetic energy of the particles is converted into heat. However, the airflow generated in the crushing cavity cannot carry away all the heat, resulting in a gradual increase in temperature.

[0007] 2) The structure design of the rotating wheel and the stator wheel is unreasonable, so that the mechanical energy cannot be effectively converted into the energy required for particle crushing, but is converted into heat in the form of friction, resulting in temperature rise. SUMMARY

[0008] In view of the above problems existing in the prior art, the first object of the present application is to provide a low-temperature liquid-cooled micro-pulverizer which can reduce the temperature rise problem caused by pulverization.

[0009] The second object of the present application is to provide the application of the low-temperature liquid-cooled micro-pulverizer.

[0010] The technical scheme for achieving the above-mentioned objects of the present application is as follows: A low-temperature liquid-cooled micro-pulverizer, which is provided with an inlet hopper through which materials enter a pulverizing zone, the pulverizing zone being a cavity surrounded by an end cover and a rotating wheel and a stator ring, and the top of the end cover being provided with a discharge port; the pulverizing zone is of a vertical structure, and the stator ring is provided with a grading baffle inside, and the grading baffle is provided with a grading wheel (the area surrounded by the grading baffle is a grading zone). The rotating wheel is in the shape of a disc, and the side of the rotating wheel facing the grading zone is provided with a hammer knife. The grading wheel is in the shape of a circular truncated cone and coaxial with the rotating wheel, and the upper end (the end with a larger diameter) of the circular truncated cone faces the discharge direction. The stator ring is coaxial with a cooling jacket, and the stator ring is located inside the cooling jacket.

[0011] The cooling jacket is provided with an inlet and an outlet, and the cooling jacket has circulating cooling liquid inside; the flow channel of the cooling jacket is one of a spiral type, an integral type, a circumferential type, and an axial type.

[0012] The material of the hammer knife is hard alloy steel, and the top surface of the part of the hammer knife facing the grading zone is provided with an inclined surface.

[0013] The traditional hammer head structure is a cuboid, which can only generate a circumferential force on the powder, while the inclined angle hammer knife can generate an axial component force on the powder. According to the radius and speed of the wheel disc, the length L of the hammer knife is determined to be 24 mm. The width W of the hammer knife is 18 mm. The width W of the hammer knife is usually determined by the maximum feed size of the equipment and the shape of the material, and is usually 3-4 times the feed size. In view of the fact that the feed size in this study is measured to be 1-5 mm, the width W is taken as 18 mm to enhance the wear resistance of the hammer knife.

[0014] Further, the inner side angle of the hammer knife is θ 1The angle is 45° (the angle between the bevel of the hammer blade and the surface of the plumb bob), and the thickness T is 15mm. The reasonable size design of the hammer blade ensures its strength and stability during the crushing process.

[0015] Wherein, the upper diameter L of the grading wheel h R is 0.4~0.6 w R w The diameter of the rotating wheel is 0.8-0.9 times that of the upper end.

[0016] Preferably, the upper diameter L of the grading wheel h 0.5 R w The diameter is 126 mm. The lower diameter is 100 mm.

[0017] Wherein, the height H of the grading wheel w 0.5~0.7 L l L l The diameter of the lower end of the grading wheel is 71°; the inclination angle of the grading wheel blades is 71°.

[0018] The tilt angle of the blades affects the classification efficiency. When the tilt angle of the classifier blades is 71°, the corresponding D... 90 It can reach over 150 μm.

[0019] Wherein, the stator ring is an annular arrangement of multiple rectangular toothed stators; the flow channel thickness of the cooling jacket is 25 mm; and the stator material is food-grade 304 stainless steel; and / or The stator teeth are helical, and the clearance between the stator tooth tip and the rotating wheel is 4 mm. The spacing of the stators is matched with the width of the working trajectory of the hammer blades on the rotating wheel.

[0020] Among them, the rake angle of the stator teeth θ 3 105° (the angle between the right side of the stator and the corresponding sectional plane of the inner wall of the jacket when viewed from above), rear angle θ 1 It is 75°, apex angle θ 2 The angle is 90°, and the tooth pitch p is 15~18 mm.

[0021] From a top-down view, the rotating wheel rotates clockwise; the rotating wheel first passes the front corner... θ 3 .

[0022] More preferably, the tooth pitch p = 17 mm. Tooth height L S1 =10 mm, L S2 =12.6 mm.

[0023] The application of the low-temperature liquid-cooled micro-pulverizer described in this invention in the pulverization of peanut cake, wherein the peanut cake is a semi-fat peanut cake obtained by low-temperature cold pressing.

[0024] The semi-fat peanut cake generally contains 10%-15% oil.

[0025] Furthermore, the process parameters for pulverizing peanut cake using the aforementioned low-temperature liquid-cooled micro-pulverizer are as follows: ethylene glycol is used as the cooling medium, the cooling medium flow rate is 1~2.0 m / s, and the temperature is -10~-20℃. For example, when the cooling medium flow rate is 1.26 m / s and the temperature is -20℃, the particle temperature is 26.38℃, and the flow channel pressure drop is 9957.06 Pa.

[0026] The rotating wheel has a rotational speed of 3000-6000 rpm, and the feed rate is set to 40-50 kg / h. The grading wheel has a rotational speed of 1400-3000 rpm. In other words, the rotating wheel's adjustable range is 3000-6000 rpm, and the grading wheel's speed is adjustable within the range of 1400-3000 rpm. For example, the rotating wheel speed can be set to a value of 3400, 3980, or 4500 rpm, and the grading wheel's rotational speed can be set to a value of 1450, 1500, or 1600 rpm.

[0027] The grading system consists of an upper motor and a lower grading wheel, which are directly connected. The preferred speed of the grading wheel is 1500 rpm.

[0028] All stator inserts and gear plates are secured to the heavy housing from the back with countersunk screws to prevent loosening during operation. The joints between stator modules and the mounting surfaces between the stator and housing require a good seal to prevent dust leakage. Sealant or O-rings (if appropriate grooves are machined) are used for sealing in the design.

[0029] Compared with the prior art, the beneficial effects of the present invention are as follows: Considering the characteristics of peanut cake with 12.50% oil and 6.65% water content, as well as cost factors, a mechanical impact rotating wheel was ultimately selected. The hammer blades are raised blocks evenly distributed on the upward-facing side of the disc-shaped rotating wheel. The shape of the hammer blades on the rotating wheel is a key structural element in the material crushing process; different angles affect the force applied to the material during crushing. A reasonable angle and shape design can significantly improve crushing efficiency, converting more mechanical force into crushing kinetic energy. In this study, the hammer blades adopt a double-beveled side design. When the inclination angle... θ 1 The grinding efficiency is optimal at a temperature of 45°.

[0030] This study innovatively redesigns the existing crusher screen, incorporating it into an integrated structure of the jacket and stator wheel. The jacket contains hollow channels, 25 mm thick, for coolant flow. The stator is fixed within the jacket. With the addition of a cooling system, rapid cooling of the stator is achieved through heat conduction. The tooth pitch is matched to the working trajectory width of the rotating wheel blades, and the tooth height ensures sufficient wear life.

[0031] To ensure ease of manufacturing and increase instantaneous impact force, the design... θ 2 It is 90°. At the same time, a larger front angle is designed. θ 3 The angle is 105° to enhance the scraping and grinding action on materials, rather than simple impact. A smaller back angle is designed. θ 1 The angle is 75° to prevent material particles from accumulating at the root of the rear angle, ensure that there is no severe friction between the tooth back and the material, and reduce wasted effort and temperature rise.

[0032] C. Circumferential type: The outlet temperature is relatively high, the uniformity is good, the pressure loss is low, and the average temperature is at a relatively high level, which comprehensively balances the energy utilization rate and the flow resistance. Therefore, the circumferential type flow channel achieves a balance between heat transfer efficiency and flow resistance, and can maintain a better outlet temperature distribution.

[0033] Under the peanut cake pulverizing process conditions defined in this invention, the particle temperature can be controlled at 26.38℃, which is within the target temperature range, and the system pressure drop is maintained in the ideal range of 9957.06 Pa.

[0034] This invention proposes a low-temperature liquid-cooled micro-pulverizer to address the problems of material blockage and protein denaturation caused by temperature rise inside the grinding chamber during the grinding of peanut cake in current pulverizers. A low-temperature micro-pulverizer for peanut cake grinding is designed, incorporating a cooling jacket and defining its internal flow channel structure. This reduces the temperature rise during grinding, thereby decreasing the oil leakage rate of peanut cake particles, preventing material blockage, and simultaneously preventing protein denaturation. Attached Figure Description

[0035] Figure 1 The average temperature rise curves for the crushing chamber are shown below. a: Average temperature rise curve during idling; b: Average temperature rise curve for feeding.

[0036] Figure 2 The curves show the correlation between temperature, emulsifiability, and emulsification stability.

[0037] Figure 3 This is a schematic diagram illustrating the relationship between temperature-foaming properties and foaming stability. Figure 4 This is the temperature-angle of repose correlation curve.

[0038] Figure 5 This is the correlation curve between compression temperature and compression strength.

[0039] Figure 6 This is a simplified structural diagram of a crusher.

[0040] Figure 7 This is a cross-sectional view of section AA.

[0041] Figure 8 This is a simplified diagram of the rotating wheel structure.

[0042] Figure 9 A simplified model of the hammer knife.

[0043] Figure 10 This is a simplified diagram of a graded wheel structure.

[0044] Figure 11 3D diagram of the jacket and stator; 1. Stator ring; 2. Hexagonal head bolt holes; 3. Coolant inlet; 4. Coolant outlet; 5. Feed port flange. Figure 12 This is a schematic diagram of the forces acting on the stator. Figure 13 Here are simplified diagrams of four flow channel structures: A. Spiral flow channel, B. Integral flow channel, C. Circumferential flow channel, and D. Axial flow channel.

[0045] Figure 14 The following are flow channel temperature cloud diagrams. (a) Spiral flow channel (b) Integral flow channel (c) Circumferential flow channel (d) Axial flow channel.

[0046] Figure 15 This is a radar chart of CFD indicators.

[0047] The correspondence between the numbers and components in the diagram is as follows: 1. Grading wheel motor; 2. Discharge hopper; 3. Grading zone; 4. Crushing zone; 5. Air inlet; 6. Frame; 7. Stator ring; 701. Stator; 8. Grading wheel; 801. Grading wheel blades; 9. Grading baffle; 10. Cooling jacket; 101. Hex head bolt hole; 102. Coolant inlet; 103. Coolant outlet; 11. Rotating wheel; 112. Main shaft hole; 113. Internal hexagonal threaded hole; 114. Hammer cutter; 12. Feed inlet. Detailed Implementation

[0048] The following examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0049] Unless otherwise specified, all test materials and instruments used in this instruction manual are commercially available.

[0050] Example 1: Detection of the physicochemical properties of peanut cake This study used peanut cake made from the widely cultivated Luhua 14 variety, processed through low-temperature pressing, as raw material. The protein content, oil content, and moisture content of the peanut cake were determined. Moisture content was determined according to GB5009.3-2016 standard. Fat content was determined according to GB5009.6-2016 standard using the Soxhlet extraction method. Protein content was determined according to GB5009.5-2016 standard using the Kjeldahl method.

[0051] Temperature rise detection of the crusher: Significant differences exist in the temperature rise of various components within the crushing chamber under idling and feeding conditions. During idling, each component reaches its maximum temperature within 25 minutes; however, after feeding, it takes approximately 90 minutes for each component to reach its peak temperature. During idling, the maximum temperature difference between the rotating wheel, stator, and crushing gap is 0.5℃. In most cases, the temperature of the rotating wheel is higher than that of the stator wheel because the rotating wheel is connected to the main shaft and transmission system, resulting in a slightly higher temperature rise. The obtained data was fitted, and the variance was calculated by taking the average of three sets of data using the least squares method. With a confidence interval set to 95%, an order of 3, and an error of 0.99, the average temperature curve of the crushing zone is obtained as shown below. Figure 1 The fitting equations can be used to obtain the average temperature rise of the crusher during internal idling at room temperature and after feeding, providing a theoretical basis for the simulation experiment in Chapter 4.

[0052] Emulsifying properties and emulsion stability: The emulsifying properties and emulsion stability of the powder (a product obtained after crushing peanut cake) were tested. The results are shown in [the table below]. Figure 2 The results showed that the emulsifying properties and emulsifying stability of peanut cake powder gradually decreased with increasing grinding temperature. At 30℃, its emulsifying properties reached their highest value of 59.51%; simultaneously, its emulsifying stability also reached its optimal state of 52.31%.

[0053] Foaming performance and foam stability: This experiment used a modified Waring-Blender method (oscillation-high-speed shear combined method) combined with a static settling method to simultaneously evaluate the kinetic behavior of the foaming performance and foam stability of the samples. Results are shown below. Figure 3 The results showed that the foaming properties and foam stability of peanut cake powder treated under different temperature conditions both decreased with increasing temperature, and the decrease in foaming properties was significantly greater than that in foam stability.

[0054] Measurement of the angle of repose: A small angle of repose θ indicates weak friction and adhesion between particles, resulting in good particle flowability; conversely, a large angle of repose θ indicates strong particle adhesion and poor flowability. See also... Figure 4Temperature-angle of repose curves were obtained. Experimental results show that as the grinding temperature increases, the angle of repose of the powder generally increases, and there is a significant increase in the two temperature ranges of 40~45℃ and 65~75℃. This change is closely related to the increase in the oil penetration rate of the particles.

[0055] Relationship between peanut cake crispness and temperature: Peanut cakes from different locations within the same batch were selected and cut into small pieces of the same shape (1×1 cm). These pieces were then cooled to different temperatures. The cooled pieces were placed in a texture analyzer for compression testing. The probe was set to compression mode, the pre-test speed was set to 1 mm / s, the test speed was set to 1 mm / s, and the trigger force was set to 5 g. This was used to investigate the relationship between peanut cake crispness and temperature. The maximum peak force was read from the texture analyzer curve as the main indicator of crispness. The experimental results are shown below. Figure 5 As shown, the peak stress of peanut cake gradually decreases with increasing temperature, indicating a gradual decline in its brittleness. In the range of -20℃ to 0℃, the peak stress remains relatively high and shows a gradual decreasing trend. When the temperature is around 0℃ to 30℃, the curve slope is relatively stable, meaning that the change in brittleness is not significant with increasing extrusion temperature. However, after 30℃, the maximum stress decreases sharply, indicating a significant reduction in brittleness. The above research suggests that setting the temperature within the grinding chamber between 20℃ and 30℃ is most beneficial for grinding; further temperature reductions significantly increase energy consumption and result in a slow increase in brittleness.

[0056] in conclusion: (1) The physicochemical properties of the pressed peanut cake were tested, and its moisture content was found to be 6.65%, fat content was 12.5%, and protein content was 56.61%.

[0057] (2) The temperature rise of the crusher under idling and feeding conditions was measured. The results showed that the highest temperature under idling conditions was 46.5℃ and the temperature under feeding conditions was 75℃.

[0058] (3) Compression tests using a texture analyzer showed that the brittleness of peanut cake increased with decreasing temperature, with the best brittleness effect observed in the range of 20℃ to 30℃. Further decreasing the temperature would cause the peak stress to increase slowly, but it would also lead to increased energy consumption. Taking all factors into consideration, the target temperature for the material was determined to be 20-30℃ in the crushing chamber.

[0059] Based on the research results in this section, the structure and parameters of the micro pulverizer were designed and optimized.

[0060] Comparative Example A commercially available Type 20 ambient temperature grinder was used to grind peanut cake at room temperature. The following problems were found: 1) The equipment exhibits a significant temperature rise during prolonged grinding. This is because the temperature of oily materials increases during grinding, causing oil to seep out and reducing the material's brittleness, leading to particle adhesion, blockage, and protein denaturation. Furthermore, in commercially available horizontal grinding structures, the powder is often located at the bottom of the grinding chamber, resulting in poor grinding uniformity.

[0061] 2) According to the test results, as the grinding temperature of peanut cake powder increases, its protein activity gradually decreases and its protein solubility also decreases, which has an adverse effect on the nutritional value of the food.

[0062] 3) The sieve structure is not suitable for micro-grinding, and its maximum fineness is only 125 μm.

[0063] Therefore, the development of a low-temperature micro-pulverizer should be based on the following design requirements: 1) A low-temperature cooling system is used to maintain the temperature at 20-30℃ during the pulverizing process; 2) The rotating wheel and stator can more efficiently convert kinetic energy into the energy for particle crushing.

[0064] In response to the problems and causes of existing micro pulverizers, this study will innovate the design of the key structures of the micro pulverizer, mainly including a low-temperature refrigeration system, rotating wheel cutter blocks and stator wheel, and a classification system. Example 2

[0065] See Figure 6 and Figure 7 This embodiment provides a cryogenic liquid-cooled micro-pulverizer. The cryogenic liquid-cooled micro-pulverizer is equipped with a feed inlet 12, through which material enters the pulverizing zone 4. The pulverizing zone is a cavity enclosed by an end cover, a rotating wheel 11, and a stator ring 7. A discharge hopper 2 is located on the top of the end cover. The pulverizing zone 4 has a vertical structure. A classifying baffle 9 is provided inside the stator ring, and a classifying wheel 8 is provided inside the classifying baffle 9. The classifying wheel 8 is a frustum-shaped structure composed of multiple classifying wheel blades 801 and is coaxial with the rotating wheel, with the upper end of the frustum facing the discharge direction. The classifying zone 3 is the area enclosed by the classifying baffle 9. An air inlet 5 is located below the rotating wheel. The classifying wheel is driven by a classifying wheel motor 1; the motor driving the rotating wheel 11 is located in the middle of the frame 6. During equipment operation, peanut cake raw materials are continuously fed into the grading baffle 9 through the side wall feed port 12 and the screw conveyor, and then enter the grading wheel 8. The sieved particles go upward into the discharge hopper 2; larger particles continue to be crushed downward. After entering the crushing chamber, the particles are thrown towards the stator ring under the impact of the high-speed rotating cutter disc. Then, through repeated collisions within the crushing gap between the stator and the rotating wheel, the material is refined. The crushed micro-particles are extracted by a connected induced draft fan through the discharge hopper 2. Smaller particles pass sequentially through the rotating classifying wheel, cyclone separator, and pulse bag filter before being collected and discharged. Larger particles are intercepted by the classifying baffle 9 and returned to the crushing chamber for secondary crushing until the required particle size is achieved. The crusher has an air inlet 5 at the bottom and an airflow passage within the crusher. The upward-facing micro-particles separated by the classifying wheel and the upward-facing air outlet both serve as the discharge hopper 2.

[0066] This micro pulverizer features a vertical pulverizing zone (4) to enhance uniformity during pulverization. Simultaneously, the screen is designed with a grading wheel structure, significantly improving pulverization fineness. A low-temperature module is added to reduce the temperature during the pulverization process. During operation, peanut cake raw materials are continuously fed into the pulverizing chamber through the side inlet via a screw conveyor. Upon entering the pulverizing chamber, the materials are thrown towards the stator ring under the impact of the high-speed rotating cutter disc. Subsequently, the materials are refined through repeated collisions within the pulverizing gap between the stator and the rotating wheel.

[0067] After the coolant enters the equipment through the inlet, it circulates inside the cooling jacket 10 and is discharged from the outlet. Then it enters the external chiller unit for cooling. The cooled coolant is then transported back to the cooling jacket to form a continuous low-temperature circulation system to maintain the working temperature of the crushing chamber.

[0068] Table 1 Operating parameters of the cryogenic micro-pulverizer

[0069] The output of this low-temperature micro-pulverizer is set at 40-50 kg / h. Since the raw material used in this study is a viscous material containing 12.50% oil and 6.65% water, the design of the pulverizing gap should help avoid excessive compression of the peanut cake, which would increase the oil yield and prevent particle agglomeration. Therefore, in this embodiment, the pulverizing gap is designed to be 4 mm.

[0070] Example 3 Structural Design Rotary wheel structures include turbine type, mechanical impact type, classifying type, and hammer type. The turbine type is suitable for high-speed rotation and can generate strong air pressure during the crushing process, integrating multiple functions such as impact, shearing, grinding, and air classification. However, its drawbacks include a small crushing gap and a large blade area. When the material has a high oil content, it can cause blockage at the blade roots or material adhesion, leading to a series of problems such as temperature rise and protein denaturation.

[0071] Mechanical impact structures are relatively simple, have a wide range of applications, are easy to install and disassemble, and have a wide range of particle size adjustment (D). 50(The diameter is 5-75 m). However, this structure has certain drawbacks: the blades are prone to wear, the gaps between the blades are easily blocked when crushing tough materials, and the heat generated during continuous operation is relatively large.

[0072] Taking into account the characteristics of peanut cake with an oil content of 12.50% and a water content of 6.65%, as well as cost factors, a mechanical impact rotating wheel was ultimately selected, and its shortcomings were improved. To ensure effective control of variables before and after the experiment, the diameter R of the rotating wheel was... w The rotational speed ω remained consistent with the initial test pulverizer, at 252 mm and 3980 rpm respectively. (See [reference]). Figure 6 The rotating wheel 11 is disc-shaped, and a hammer 114 is provided on the side of the rotating wheel facing the grading area. The center of the rotating wheel is a main shaft hole 112, and the wheel is provided with an internal hexagonal thread hole 113.

[0073] 1) Hammer blade size design The length L and width W of the hammer blades are typically determined based on material characteristics, processing capacity, and the mill's rotational speed. The length of the hammer blades can be estimated using the following empirical formula, based on the mill's rated operating conditions and the material's hardness:

[0074] Where: r is the radius of rotation of the hammer blade, in meters; n is the rotational speed of the hammer blade, in rpm.

[0075] Based on the wheel radius and rotation speed, the length L of the hammer cutter was determined to be 24 mm. The width is typically 3 to 4 times the feed particle size; however, given that the feed particle size measured in this study was 1-5 mm, the width W was chosen to be 18 mm to enhance the wear resistance of the hammer cutter. The thickness T of the hammer cutter was designed to be 15 mm.

[0076] 2) Tilt design See Figure 8 and Figure 9 In this study, the hammer blade adopts a double-bevel design on the side, and the top surface is divided into bevels; previous studies compared the inclination angles. θ 1 The crushing efficiency is measured at angles of 0°, 35°, 45°, and 55°, with the optimal efficiency achieved at an angle of 45°. Therefore, this design sets the inner side of the hammer blade to a 45° angle, and the hammer blade is a block type. θ2 (the angle between the rear side of the hammer blade and the plumb surface) is designed to be 2.86°.

[0077] Grading wheel design: This embodiment uses a rotary wheel-type eddy current classifier, whose core component is a high-speed rotating classifying wheel. The design objectives of the classifying wheel are as follows: 1) Achieve the target cutting particle size D 50It can be continuously adjusted by changing the rotation speed.

[0078] 2) Ensure that the flow field in the blade channel is uniform under the condition of processing gas volume, and avoid blockage and dust accumulation.

[0079] 3) It meets the requirements for strength and dynamic balance and can operate safely at the highest operating speed.

[0080] 4) The structure is simple and easy to process and assemble.

[0081] Rotational Speed ​​Study and Design: The classifier wheel is the core component of the air classifier. Through high-speed rotation, it creates a strong centrifugal field between the blades, achieving dynamic particle classification. When material enters the classification zone with the airflow, the particles are subjected to two opposing forces: Centrifugal force:

[0082] F c -The centrifugal force acting on the particle, m p —mass of a single particle, ω—angular velocity, r—radius of the contact point; Air resistance (inward):

[0084] F d - Airflow resistance experienced by the particles C d -Drag factor, ρ g -Air density, A p -Particle projection area u r —Relative velocity between particles and fluid Only when the particle size is small and the inward resistance is greater than the centrifugal force can the particles pass through the blade gaps with the airflow and be collected as fine powder; otherwise, the particles are thrown back to the outside and become coarse powder. This invention designs a low-temperature ultrafine pulverizer D... 50 The particle size is 45μm, which is far lower than the D value of room temperature ultrafine grinding of oily materials on the market. 50 The range is 125-75μm, which improves the fineness after pulverization.

[0085] Angular velocity:

[0086] Substituting the existing peanut and air parameters, the grading wheel speed is found to be 1500 rpm.

[0087] Parameters of the graded wheel structure: See Figure 10The classifying wheel is frustum-shaped and coaxial with the rotating wheel, with the upper end of the frustum facing the discharge direction. The design parameters of the classifying wheel include the upper diameter L. h Lower end diameter L l Blade tilt angle θ w Blade height H w Quantity and thickness. The upper diameter is designed to be 0.5R. w The diameter is 126 mm. The lower diameter is 0.8-0.9 times the upper diameter; a smaller diameter is beneficial for the installation of the grading wheel, therefore it is designed to be 100 mm. The height H of the grading wheel... w 0.5~0.7L l The blade tilt angle affects the classification efficiency. There is a clear mathematical relationship between the critical particle size at the classification point and the blade tilt angle. Based on the principle of particle force balance (centrifugal force = airflow resistance), we can obtain:

[0088] In the formula: D 90 —Particle fineness of 90%, initially determined to be 150 μm, μ—gas viscosity (Pa·s), Q—working fluid flow rate (m³ / s), ρ s , ρ g —Particle and gas density (kg / m³), h—Distance between the upper and lower blades of the rotating wheel (m), R—Average radius of the rotating wheel (m), s—Radial displacement corresponding to the cone angle of the rotating wheel (m), θ w — Blade tilt angle (°) By consulting the material parameter handbook and substituting the known data, we can obtain the value when the classifier tilt angle θ... w When it is 71°, it corresponds to D 90 Achieve a particle size of 150 or less; Fineness D 50 <45 μm, which meets the food industry micro-pulverization standard.

[0089] Jacket and stator wheel design: like Figure 11 As shown, the stator ring 7 is an annular structure composed of multiple stators 701. The cooling jacket 10 and the stator ring 7 are designed as an integrated structure to improve heat transfer efficiency. The cooling jacket is provided with hexagonal head bolt holes 101. The coolant inlet 102 and coolant outlet 103 of the cooling jacket 10 are connected to an external chiller. Coolant is introduced into the jacket to cool the internal crushing zone. In this study, food-grade 304 stainless steel was selected as the manufacturing material for the stator, as this material has corrosion resistance and meets food safety standards.

[0090] The stator teeth are designed as helical teeth, and the gap between the stator tooth tip and the rotating wheel is set to 4 mm to prevent the material from clogging due to excessive oil extrusion.

[0091] A mechanical analysis was performed on the collision between stator 701 and the particles. F4 is the force generated by the particle colliding with the right side of the stator, and F3 is the force generated by the particle colliding with the front of the stator. θ 3 For the front corner, θ1 For the rear corner, θ2 It is the vertex angle. θ2 The larger the impact force F3, the greater the impact force. Therefore, to ensure ease of manufacturing, the design... θ2 It is 90°. At the same time, a larger front angle is designed. θ 3 The angle is 105° to enhance the scraping and grinding action on materials, rather than simple impact. A smaller back angle is designed. θ1 The angle is 75° to prevent material particles from accumulating at the root of the rear angle, ensuring no severe friction between the tooth back and the material, and reducing wasted energy and temperature rise. The tooth pitch is typically 1-2 times the tooth width; therefore, the tooth pitch p is determined to be 17 mm. Tooth height L... S1 =10 mm, L S2 =12.6 mm ( Figure 12 ).

[0092] All stator inserts and gear plates are secured to the heavy housing from the back with countersunk screws to prevent loosening during operation. The joints between stator modules and the mounting surfaces of the stator and housing are sealed with sealant or O-rings.

[0093] Cooling channel structure design: The total heat generated during machine operation is calculated based on the energy conservation formula, and the heat generated in the crushing chamber per hour is 15259 KJ.

[0094] For heat transfer in a pulverizer, the main heat cycles include: air cooling circulation, heat removal from the jacket, heat dissipation from the machine surface, and heat removal by the particles. For a rotating wheel with a speed of 3000-6000 rpm and a diameter of 252 mm, the calculated heat removal capacity of the circulating air is 7735.25-8973.65 KJ per hour. For a feed rate of 50 kg / h and an ambient temperature of 25℃, the formula for calculating the heat removal by the particles is: Calculations show that at a particle feed rate of 50 kg / h, the particles carry away 2322.5 KJ of heat. Neglecting the machine's own heat dissipation, 5201.25-3962.85 KJ of energy remains uncarried. This heat is carried away by the cooling effect of the flow channel, thus achieving a cooling effect on the grinding chamber.

[0095] Calculation of cooling capacity of flow channel: See Figure 13The spiral flow channel is wound around the outer wall of the stator in a spiral shape; the circumferential type consists of multiple parallel flow channels wound around the outer wall of the stator; and the axial type flow channel is parallel to the stator axis. To systematically compare the heat transfer performance of the four types of cooling flow channels—spiral, integral, circumferential, and axial—this study integrates thermodynamic energy balance and heat transfer analysis methods to construct a mathematical model for refrigeration efficiency.

[0096] Common cryogenic cooling media include water, ethylene glycol aqueous solution, silicone oil, and liquid nitrogen. Pure water has a high freezing point, making it unsuitable for the cryogenic operating conditions of this equipment. The phase change process of liquid nitrogen is complex to control and not suitable for the mechanical refrigeration cooling cycle employed in this equipment. Silicone oil has high viscosity at low temperatures and is also expensive. In summary, ethylene glycol aqueous solution demonstrates significant advantages in the specific application scenario of this study. The density ρ of the coolant can be determined to be 1134 kg / m³, and the initial temperature of the coolant is selected as 0℃.

[0097] The heat transfer area A of the four types of cooling channels needs to be calculated separately based on their respective geometric characteristics: the heat transfer area of ​​the spiral channel increases with the increase of the spiral length; the heat transfer area of ​​the integral (encased) channel is approximately the outer surface area of ​​the entire grinding chamber; the heat transfer area of ​​the circumferential channel is related to the number and diameter of the loops; the heat transfer area of ​​the axial channel depends on the number of channels and the axial length. The mathematical relationship between the geometric parameters of each channel and its heat transfer area is established, where the refrigerant density is 1134 kg / m³, the dynamic viscosity is 0.165 mPa·s, and the dynamic viscosity is 0.088 W·m⁻¹·K⁻¹; a 4.5KW water-cooled chiller is selected. Specific channel parameters are shown in the table below: Table 2 Specific parameters of the flow channel

[0098] Calculations show that to reduce the temperature of the grinding chamber to the optimal range for peanut cake crispness (20℃ to 30℃), the jacket cooling capacity needs to reach 4.13 KW-6.645 KW. Assuming consistent cooling capacity across different flow channels, the following flow velocities are derived: 1.62-2.43 m / s for the spiral flow channel jacket, 1.43-2.15 m / s for the integral flow channel, 1.49-2.24 m / s for the circumferential flow channel, and 1.58-2.37 m / s for the axial flow channel. The research results show that, under the condition of injecting 0℃ coolant, when the flow velocity of the spiral flow channel jacket is 1.62-2.43 m / s, the flow velocity of the integral flow channel is 1.43-2.15 m / s, the flow velocity of the circumferential flow channel is 1.49-2.24 m / s, and the flow velocity of the axial flow channel is 1.58-2.37 m / s, the cooling effect of the crushing chamber at the target temperature of 20-30℃ can be achieved.

[0099] Example 4: CFD-DEM Coupled Simulation The three-dimensional model (Step format) of the cryogenic micro-pulverizer was imported into the coupled simulation system. The model consists of three parts: a cryogenic flow channel, a pulverizing zone, and a shell. The model was meshed using ANSYS Workbench 2023 software. In the simulation, the standard k-ε turbulence model was used in Fluent CFD software, and the Hertz-Mindlin model was selected for particle contact. In EDEM 2023, the particles were modeled as hard, viscous spheres, and particle agglomerations were added.

[0100] To ensure consistent theoretical cooling capacity across all cooling channels, the inlet velocity was set to 1.62 m / s for the spiral channel, 1.55 m / s for the integral channel, 1.57 m / s for the axial channel, and 1.58 m / s for the circumferential channel. This was used to investigate the specific cooling effect under controlled variable conditions of the same cooling capacity. The coolant temperature was set to 0℃. The outlet was set to escape, the wall surface was set to heat conduction and radiation, and the stator wheel wall surface was set to heat convection. The following fitting formula was used to import data related to particle collisions and high-speed heat generation: Y=(31.27524)+(0.75382)*x+(7.49417E-4)*X 2 +(-4.12976E-5)*X 3 In the formula: Y—average temperature rise inside the grinding chamber, kJ; X—grinding time, s. Analysis of temperature and flow field simulation results: The CFD simulation results are as follows: Figure 14 As shown, the highest temperature in the simulation area is 350K and the lowest temperature is 300K. These temperature displays are based on the steady-state model.

[0101] In the four flow channels, the blue area predominates, indicating a lower overall temperature. The inlets are all dark blue, signifying a continuous inflow of 0°C coolant, while the outlet temperatures vary. Measurements showed the outlet temperatures, from highest to lowest, to be: circumferential flow channel > axial flow channel > integral flow channel > spiral flow channel. This indicates that, under the same mass flow rate and coolant parameters, the cooling effect, from highest to lowest, is: circumferential flow channel > axial flow channel > integral flow channel > spiral flow channel.

[0102] The temperature distribution in the circumferential flow channel is relatively clear, without forming a mixed temperature field, and no "backflow" effect is observed at the outlet. This indicates that compared to the integral flow channel, the circumferential flow channel improves fluid flowability, reduces the probability of turbulence formation, and thus improves heat transfer efficiency and level. Furthermore, both the circumferential and axial flow channels exhibit a darker color along the lower edge of the coolant, indicating a significant boundary layer effect at this point. This results in a slower liquid circulation speed, reduced heat removal, and consequently, a higher temperature in this region compared to the upper region.

[0103] Throughout the entire test cycle, the pressure loss of the circumferential flow channel is similar to that of the integral type. The pressure increases from 4s. Due to the stronger determinism of the internal flow path compared to the integral type, the pressure loss is smaller at 6s. At the same time, there is a small vortex at its outlet, which causes the pressure rise rate to be higher than that of the spiral flow channel but lower than that of other types of flow channels.

[0104] The simulation results are assigned values ​​and normalized. The values ​​assigned to positive indices (higher is better, such as outlet temperature, outlet temperature uniformity, and average temperature) are as follows: "High" → 5, "Slightly High" → 4, "Slightly Low" → 2, "Low" → 1 The values ​​assigned to the inverse indicators (lower is better, such as pressure loss and maximum temperature) are as follows: "Low" → 5, "Slightly Low" → 4, "Slightly High" → 2, "High" → 1 like Figure 14 As shown, a comparison is made from a comprehensive perspective of multiple indicators: A spiral type: good uniformity and low pressure loss, but the outlet temperature and average temperature are both low, which may lead to insufficient thermal energy utilization in downstream processes; Type B: The average temperature is the highest, but the uniformity and pressure loss performance are not good, and the structure is limited and has low flexibility. C-type circumferential type: higher outlet temperature, better uniformity, lower pressure loss, and higher average temperature, which comprehensively balances energy utilization and flow resistance. D-axis type: high pressure loss, poor uniformity and excessively high maximum temperature, making it difficult to meet thermal management performance requirements.

[0105] See Figure 15 The circumferential flow channel achieves a balance between heat transfer efficiency and flow resistance, and can maintain a better outlet temperature distribution. Although its maximum temperature is slightly higher, it can be controlled by fine-tuning the local structure. Its overall thermal-flow performance is the best among the four schemes, and it is determined to be the final design scheme.

[0106] Example 5: Determining Optimal Operating Parameters through Orthogonal Experiments The previous section mainly analyzed the effects of coolant flow rate and temperature on particle temperature rise and pressure drop. Therefore, this section identifies these two parameters as two experimental factors. Considering both temperature and pressure drop, to effectively reduce the number of experimental analyses, only three representative levels need to be selected from the five levels for analysis. Based on the trend of the single-factor comprehensive analysis in the previous section, the three selected levels are shown in Table 4 below. Where A represents the proportion of the flow channel cross-section shape, and B represents the flow medium velocity. Factor A: Coolant inlet temperature T (°C), Factor B: Coolant inlet velocity V (m / s). Based on engineering requirements and the scope of previous experiments, the following three levels are determined: Table 3 Experimental factors and levels Horizontal A（℃） B (m / s) 1 -20 0.5 2 0 1.5 3 20 2.5 The experiment shows that, among the two factors of coolant temperature and flow rate, P-value B and P-value A are both <0.001, indicating that factors A and B have a very significant impact on particle temperature. The coupling method between the model contour plot and the response surface curve is as follows: the particle temperature and pressure drop in the model are set to minimum, and the rest are set within the temperature range. Considering that temperature has a greater impact in actual grinding, while pressure drop less than 10000 Pa is sufficient, the particle temperature weight is set to 2. The optimal coupling result is: coolant flow rate 1.26 m / s, temperature -20℃, at which point the particle temperature is 26.38℃ and the channel pressure drop is 9957.06 Pa.

[0107] Taking a circumferential flow channel as the research object, this study investigated the influence mechanism of key operating parameters (coolant velocity and temperature) on particle cooling effect and system pressure drop using CFD-DEM coupled simulation. Finally, based on a two-factor, three-level orthogonal experimental design, the coolant velocity and temperature parameters were optimized. The optimal operating parameter combination for the circumferential flow channel was determined to be: coolant velocity 1.26 m / s and coolant temperature -20℃. Under these conditions, the particle temperature can be controlled at 26.38℃, within the target temperature range, and the system pressure drop remains within the ideal range of 9957.06 Pa. Example 6

[0108] This embodiment proposes a cryogenic liquid-cooled micro pulverizer. The cryogenic liquid-cooled micro pulverizer is equipped with a feeding hopper. The material enters the pulverizing zone through the feeding port 12. The pulverizing zone is a cavity surrounded by an end cover, a rotating wheel, and a stator. The top of the end cover is provided with a discharge port. The pulverizing zone has a vertical structure and a classifying wheel is provided inside the pulverizing zone. The rotating wheel is disc-shaped, and a hammer blade is provided on the side of the rotating wheel facing the grading area. The rotating wheel has one of the following structures: turbine type, mechanical impact type, grading type, and hammer blade type. The grading wheel is frustum-shaped, and the frustum and the rotating wheel are coaxial, with the lower surface of the frustum facing the discharge direction. The stator and the cooling jacket are coaxial, with the stator located inside the cooling jacket; the cooling jacket is provided with a liquid inlet and a liquid outlet, and there is circulating coolant inside the cooling jacket; The hammer blade is made of cemented carbide steel, with a length L of 24 mm and a width W of 18 mm. The inner inclination angle θ1 of the hammer blade is 45°, and its thickness T is 15 mm.

[0109] The upper diameter L of the grading wheel h 0.5 R w The diameter is 126 mm. The lower diameter is 100 mm. The height H of the grading wheel is... w 0.6 L l L l The diameter of the lower end of the grading wheel is 71°; the inclination angle of the grading wheel blades is 71°.

[0110] The stator ring is a ring composed of multiple stators arranged in a circle. The flow channel thickness of the cooling jacket is 25 mm. The stator tooth pitch is adapted to the width of the working trajectory of the rotating wheel blade. The stator material is food-grade 304 stainless steel. The stator teeth are helical, and the width of the gap between the stator tooth tip and the rotating wheel is 4 mm. The stator tooth rake angle θ3 is 105°, clearance angle θ1 is 75°, tip angle θ2 is 90°, and tooth pitch p = 17 mm. Tooth height L S1 =10 mm, L S2 =12.6 mm. Example 7

[0111] This embodiment provides the use of the low-temperature liquid-cooled micro-pulverizer described in Embodiment 6 to pulverize peanut cake, wherein the peanut cake is a semi-fat peanut cake obtained by low-temperature cold pressing.

[0112] The process parameters for pulverizing peanut cake using the low-temperature liquid-cooled micro-pulverizer are as follows: ethylene glycol is used as the cooling medium, the flow rate of the cooling medium is 1~1.5 m / s, and the temperature is -10~-20℃.

[0113] The pulverizer's rotating wheel rotates at 3980 rpm, and the feed rate is set at 40-50 kg / h. The rotating wheel-type vortex classifier rotates at 1500 rpm.

[0114] This pulverization method employs a low-temperature cooling system to reduce the temperature during the pulverization process to 20-30℃; the D of the pulverized product 90 Achieving a fineness of less than 150 μm, D 50 <45 μm, which meets the food industry micro-pulverization standard.

[0115] The rotating wheel and stator of this crusher can more efficiently convert momentum into energy for particle crushing.

[0116] Although the present invention has been described above through embodiments, those skilled in the art should understand that any improvements and modifications made to the present invention without departing from its spirit and essence should fall within the protection scope of the present invention.

Claims

1. A cryogenic liquid-cooled micro-pulverizer, wherein the cryogenic liquid-cooled micro-pulverizer is provided with a feed hopper, through which material enters a pulverizing zone, the pulverizing zone being a cavity surrounded by an end cover, a rotating wheel, and a stator ring, and a discharge port is provided at the top of the end cover; characterized in that, The crushing zone has a vertical structure, and a classifying baffle is provided inside the stator ring, with a classifying wheel inside the classifying baffle; The rotating wheel is disc-shaped, and a hammer blade is provided on the side of the rotating wheel facing the grading area; the grading wheel is frustum-shaped and coaxial with the rotating wheel, with the upper end of the frustum facing the discharge direction. The stator ring and the cooling jacket are coaxial, with the stator ring located inside the cooling jacket. The cooling jacket is provided with an inlet and an outlet, and coolant circulates within the cooling jacket. The flow channel of the cooling jacket is one of the following: spiral, integral, circumferential, or axial.

2. The cryogenic liquid-cooled micro-pulverizer according to claim 1, characterized in that, The hammer blade is made of cemented carbide steel. The top surface of the hammer blade facing the grading area is set as an inclined surface. The length L of the hammer blade is 24 mm and the width W of the hammer blade is 18 mm.

3. The cryogenic liquid-cooled micro-pulverizer according to claim 1, characterized in that, The inner inclination angle θ1 of the hammer blade is 45°, and the thickness T is 15 mm.

4. The cryogenic liquid-cooled micro-pulverizer according to claim 1, characterized in that, The upper diameter L of the grading wheel h R is 0.4~0.6 w R w The diameter of the rotating wheel is 0.8 to 0.9 times the diameter of the upper end of the grading wheel.

5. The cryogenic liquid-cooled micro-pulverizer according to claim 1, characterized in that, The height H of the grading wheel w 0.5~0.7L l L l The diameter of the lower end of the grading wheel is 71°; the inclination angle of the grading wheel blades is 71°.

6. The cryogenic liquid-cooled micro-pulverizer according to any one of claims 1 to 5, characterized in that, The stator ring is an annular structure formed by multiple rectangular toothed stators; the cooling jacket has a flow channel thickness of 25 mm; and the stator material is food-grade 304 stainless steel; and / or The gap between the stator tooth tip and the rotating wheel is 4 mm.

7. The cryogenic liquid-cooled micro-pulverizer according to claim 6, characterized in that, The stator teeth are helical teeth, and the stator's rake angle... θ 3 is 105°, the front angle is the angle between the right side of the stator and the inner side of the jacket, and the rear angle is... θ 1 is 75°, vertex angle θ 2 is 90°, and the tooth pitch p is 15~18 mm.

8. The application of the low-temperature liquid-cooled micro-pulverizer according to any one of claims 1 to 7 in the pulverization of peanut cake, wherein the peanut cake is a semi-fat peanut cake obtained by low-temperature cold pressing.

9. The application according to claim 8, characterized in that, The process parameters for pulverizing peanut cake using the aforementioned low-temperature liquid-cooled micro-pulverizer are as follows: ethylene glycol is used as the cooling medium, the flow rate of the cooling medium is 1.0~2.0 m / s, and the temperature is -10 to -20℃.

10. The application according to claim 8, characterized in that, The rotation speed of the rotating wheel is adjustable from 3000 to 6000 rpm, the feeding speed is 40-50 kg / h, and the rotation speed of the grading wheel is 1400 to 3000 rpm.

Images