A horizontal crushing and mixing device

Abstract

The present invention belongs to the technical field of crushing and mixing devices, and relates to a horizontal crushing and mixing device, including a mixing drum and an agitator installed in the mixing drum in a coaxial manner, the agitator including a mixing shaft and a plurality of propeller blades fixed on the mixing shaft, a spiral blade, a plurality of groups of crushing blades, a plurality of groups of auxiliary stirring blades and a plurality of groups of discharge rods, the plurality of propeller blades, a spiral blade, a plurality of groups of crushing blades and a plurality of groups of discharge rods are arranged in sequence along the axial direction of the mixing shaft, and a plurality of groups of auxiliary stirring blades are evenly arranged along the axial direction of the mixing shaft between the spiral blade and the discharge rod; the two sides of each auxiliary stirring blade are respectively fixedly connected to the support rods of a crushing blade of each of the two adjacent groups, and the bottom side is fixedly connected to the mixing shaft. The present invention reduces the obstruction of solid materials, realizes quantitative pushing of mixed materials, improves crushing and mixing efficiency, improves equipment reliability, and reduces the material and processing costs of parts by setting the blade combination mode of each zone.

Description

Technical Field

[0001] The invention belongs to the technical field of crushing and mixing devices and relates to a horizontal crushing and mixing device. Background Art

[0002] In modern industry, crushing and mixing devices are widely used in various industrial fields. Crushing efficiency and mixing uniformity are important technical indicators for evaluating mixing devices. At the same time, the reliability of the equipment is closely related to the economic benefits and personal safety of the enterprise, and is also a very important issue.

[0003] Lyocell cellulose pulp premixer is a solid-liquid mixing device for mixing cellulose particles with NMMO aqueous solution. Lyocell fiber is known as the green fiber of the 21st century and will be a substitute for viscose fiber, protein fiber and other fibers in the future. It uses NMMO as solvent and uses dry and wet methods to spin regenerated cellulose fiber. The preparation of spinning solution is the most critical process in the production of Lyocell fiber, and the premixing effect of cellulose pulp and NMMO aqueous solution is the key to dissolution. NMMO aqueous solution and cellulose particles are put into the premixer. Under the stirring action of the blades, the cellulose particles will continue to be broken and fully mixed with the solution. If the mixing is uneven, it will bring difficulties to the subsequent dissolution, spinning and other processes, directly affecting the product quality of Lyocell fiber.

[0004] At present, there are two types of pre-mixers used in the production process of lyocell fibers: vertical pre-mixers and horizontal pre-mixers. Compared with vertical pre-mixers, horizontal pre-mixers can realize continuous preparation of cellulose pulp porridge, and the quality of cellulose pulp porridge prepared in different batches is continuous and stable. At the same time, the process conditions of horizontal pre-mixers are easy to control, maintain and clean, so they are also widely used. However, the main problems of horizontal pre-mixers in the prior art are low crushing efficiency, uneven mixing, broken blade support rods and inaccurate mixing time control.

[0005] For example, patent CN105113027A discloses a premixer for preparing lyocell fibers. The stirring blades in the device are continuous spiral blades, which have no crushing effect on the material, and there is a mixing dead zone around the stirring shaft. Therefore, this mixing device has problems such as low crushing efficiency and uneven mixing. In addition, although this technical solution can control the mixing time by means of a baffle, a mixing dead zone will be formed on both sides of the baffle, resulting in an increase in the mixing dead zone in the device.

[0006] For example, in a horizontal solid-liquid mixing device disclosed in patent CN115445468A, the stirring blade support rod has no auxiliary support, and the blade support rod is prone to stress concentration problems, which may cause the blade support rod to break; in addition, although this technical solution sets a weir plate in front of the material outlet of the mixing device to extend the crushing and mixing time of the material through the weir plate, it still cannot control the crushing and mixing time of the material.

[0007] For example, the blade combination of each zone of the agitator in patent CN218812868U is set as follows: the feeding zone and the primary mixing zone use continuous spiral blades, the mixing zone uses stirring rods, and the discharge zone uses continuous spiral blades. However, due to the large distance between the top of the continuous spiral blade and the inner wall of the cylinder in the patent structure, the structure will cause uneven swelling of cellulose particles, and cannot achieve quantitative pushing of the mixed material, and cannot accurately control the crushing and mixing time. The mixing zone of the patent adopts a stirring rod structure, which has a low crushing efficiency for swollen cellulose particles.

[0008] For example, the paddle combination of each zone of the agitator in patent CN206285753U is set as follows: each zone agitator adopts a paddle structure, and the paddle installation angles of each zone are different. However, although the paddle structure of the agitator in the mixing zone has a certain crushing effect on cellulose particles, it will also cause uneven swelling of cellulose particles, fail to achieve quantitative pushing of the mixed material, and fail to accurately control the crushing and mixing time.

[0009] In summary, the premixer currently used for the production of lyocell fiber porridge has problems such as low crushing efficiency, uneven mixing, and inaccurate mixing time control. Therefore, it is of great significance to study a horizontal crushing and mixing device to solve the above problems. Summary of the invention

[0010] The purpose of the present invention is to solve the problems existing in the prior art and provide a horizontal crushing and mixing device.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A horizontal crushing and mixing device comprises a mixing drum and a stirrer installed in the mixing drum in a coaxial manner, wherein the stirrer comprises a stirring shaft and a plurality of propeller blades fixed on the stirring shaft, a spiral blade, a plurality of groups of crushing blades, a plurality of groups of auxiliary stirring blades and a plurality of groups of discharge rods, wherein the plurality of propeller blades, the spiral blade, the plurality of groups of crushing blades and the plurality of groups of discharge rods are arranged in sequence along the axial direction of the stirring shaft, and the plurality of groups of auxiliary stirring blades are evenly arranged between the spiral blade and the discharge rod along the axial direction of the stirring shaft;

[0013] The bottom of each propeller blade is connected to a propeller blade support rod, and a plurality of propeller blades are fixed on the stirring shaft through the propeller blade support rod and are arranged in a segmented spiral;

[0014] The spiral blades are directly fixed on the stirring shaft;

[0015] The number of each group of crushing blades is more than 3, and each group of crushing blades is evenly arranged around the stirring shaft. The bottom of each crushing blade is connected to a crushing blade support rod, which is fixed to the stirring shaft through the crushing blade support rod;

[0016] The number of each group of auxiliary stirring blades is at least 3, and each group of auxiliary stirring blades is evenly arranged around the stirring shaft. Both sides of each auxiliary stirring blade are fixedly connected to the support rods of two adjacent groups of crushing blades, and the bottom edge is fixedly connected to the stirring shaft.

[0017] The discharge rod is directly fixed on the stirring shaft;

[0018] The gap between the top of the spiral blade and the inner wall of the mixing barrel is ≤15mm; the gap between the top of the spiral blade and the inner wall of the mixing barrel is set so that the spiral blade and the mixing barrel form a spiral pump structure, which can push the mixed material to the crushing and mixing zone in a quantitative manner, thereby accurately controlling the mixing time and ensuring the mixing efficiency and uniformity.

[0019] The inner area of ​​the mixing barrel of the present invention, such as Figure 3 As shown, according to the different states of cellulose particles and the main functions of the agitator, it is divided into a feeding zone 15, a swelling zone 16, a crushing and mixing zone 17 and a discharge zone 18, wherein the swelling and crushing process of the cellulose particles is a continuous and gradual process. The segmented screw blades mainly push the large-diameter cellulose particles entering the mixing device from the inlet to the next zone (swelling zone 16); the screw blades and the mixing barrel form a screw pump structure to quantitatively push the cellulose particles that have absorbed the NMMO aqueous solution to the next zone (crushing and mixing zone 17); the crushing blades crush the cellulose particles that have absorbed the NMMO aqueous solution into smaller particles, and stir and mix the small cellulose particles with the NMMO aqueous solution; the auxiliary stirring blades mainly stir and mix the small cellulose particles around the stirring shaft with the NMMO aqueous solution to promote material flow and uniform mixing; the discharge rod mainly stirs the cellulose pulp porridge at the material outlet to cause the cellulose pulp porridge to be discharged from the material outlet;

[0020] There are areas with slow flow or stillness in the reactor. These areas are dead corners of stirring and basically do not participate in the movement of materials, nor do they exchange energy with surrounding materials. These areas are called dead zones. The dead zone ratio is defined as the percentage of the dead zone material volume to the total reactor material volume.

[0021] The method of directly connecting the crushing blades to the stirring shaft in an attempt to increase the strength of the crushing blades and reduce the dead zone is not advisable. The reasons are: ① The output per unit time is reduced. Under the same mixing barrel volume, the directly connected crushing blades will occupy more space, so the volume occupied by the mixed material will be reduced, that is, the output per unit time of the mixing device will be reduced, and the unit energy consumption will also increase. ② The directly connected crushing blades will occupy the movement space of the mixed material, and too small a movement space will reduce the crushing efficiency. Assuming that the rest of the space in the mixing device is filled with materials except the agitator, when the agitator rotates, the mixed material will rotate with the agitator, and there is no relative movement between the two. The agitator will not have a crushing effect on the material, so the crushing efficiency will be lower. ③ The volume of the mixing dead zone around the stirring shaft is larger. If the crushing blades are directly connected to the stirring shaft, the blades will divide the space around the stirring shaft into several independent narrow spaces, and the materials in the space will not flow easily, and the volume of the mixing dead zone will be larger. In summary, it is not advisable to directly connect the crushing blades to the stirring shaft. In addition, if the stress concentration problem at the root of the crushing blade support rod is solved by increasing the diameter of the crushing blade support rod or changing the material, such a solution is quick, but this solution cannot reduce the volume ratio of the mixing dead zone around the stirring shaft, does not improve the mixing uniformity, and causes an increase in manufacturing costs.

[0022] The auxiliary stirring blade of the present invention fixedly connects two side edges of the auxiliary stirring blade to the support rods of two adjacent crushing blades, thereby reducing the stress at the root of the crushing blade support rod.

[0023] The connection relationship between the auxiliary stirring blade and the stirring shaft of the present invention is the same as the connection relationship between the continuous spiral blade and the stirring shaft in the prior art, but the auxiliary stirring blade of the present invention is different from the continuous spiral blade in the prior art in terms of height, arrangement along the stirring shaft direction and arrangement around the stirring shaft.

[0024] The slow flow of materials around the stirring shaft easily forms a dead zone, which is a structural defect of the horizontal mixing and stirring device itself and cannot be eradicated. The auxiliary stirring blade of the present invention has an enhancing effect on the flow rate of cellulose porridge around the stirring shaft, and can reduce the volume ratio of the dead zone around the stirring shaft, which is significantly lower than the volume ratio of the dead zone around the continuous spiral blade stirring shaft in the prior art.

[0025] The reasons why the auxiliary stirring blades of the present invention can reduce the volume ratio of the mixing dead zone are as follows: (1) Compared with the continuous spiral blades, the auxiliary stirring blades of the present invention are small in height, and the gap between the top and the inner wall of the mixing barrel is large. The materials around the stirring shaft will be thrown out at high speed in the radial direction under the action of the centrifugal force of the auxiliary stirring blades, which promotes the mixing with the materials in other regions. (2) The auxiliary stirring blades are segmented, which is conducive to the axial mixing of the materials. In the present invention, several groups of auxiliary stirring blades are evenly arranged along the axial direction of the stirring shaft between the spiral blades and the discharge rod, and the two axially adjacent auxiliary stirring blades are not connected and are non-continuous. When the material moves axially, it will stop axially at the interval between the two auxiliary stirring blades, and mix with the materials in other regions under the action of the blade support rod. Therefore, the segmented arrangement of the auxiliary stirring blades is conducive to the axial mixing of the materials. (3) Each group is evenly arranged with multiple auxiliary stirring blades, rather than a single spiral blade, which is conducive to enhancing the mixing intensity of the materials. A single continuous spiral blade has only one blade in the same axial length to stir the materials. Therefore, the single group of multiple auxiliary stirring blades structure of the present invention has a greater mixing intensity for the materials than a single spiral blade.

[0026] In summary, compared with the single continuous spiral blade in the prior art, the auxiliary stirring blade of the present invention enhances the axial and radial mixing ability of the material and can effectively reduce the volume ratio of the mixing dead zone around the stirring shaft.

[0027] Therefore, the design of the auxiliary stirring blade of the present invention achieves the dual purpose of reducing the stress at the root of the crushing blade support rod and stirring the cellulose porridge around the stirring shaft. Although there are also designs of auxiliary stirring blades in the prior art, for example, the document (Mechanism Analysis and Parameter Optimization of Paddle Diet Mixer [J]. Transactions of the Chinese Society of Agricultural Machinery, 2020, 6, 122-131) provides a rotor structure of a paddle diet mixer, in which the reinforced blade is similar to the auxiliary stirring blade of the present application, which can increase the stirring function. However, since the reinforced blade is not fixedly connected to the stirring shaft, the reaction force of the reinforced blade is completely applied to the support rod, which increases the stress concentration at the root of the support rod. This type of structure not only fails to reduce stress concentration, but also increases the stress concentration problem at the root of the support rod, increasing the use and maintenance cost of the device.

[0028] As the preferred technical solution:

[0029] In the horizontal crushing and mixing device as described above, a soft rubber plate is arranged on the top of each propeller blade. The material of the soft rubber plate is EPDM rubber. The thickness of the soft rubber plate is 5-10 mm and the hardness is 60-75 Shore A at room temperature. Due to the elastic deformation of the soft rubber plate, the occurrence of material jamming events can be reduced, thereby reducing power consumption and the probability of parts damage.

[0030] In the horizontal crushing and mixing device as described above, the spacing between two adjacent propeller blades is 40-180 mm; the rotation direction of the spirally arranged propeller blades is left-handed, which is consistent with the rotation direction of the spiral blade, and the pitch is 100-300 mm.

[0031] In the horizontal crushing and mixing device as described above, the pitch of the spiral blade is 100-300 mm, preferably 120-280 mm, and the gap between the top of the spiral blade and the inner wall of the mixing cylinder is 1-15 mm, preferably 5-10 mm.

[0032] Because the material flow rate is slow, a mixing dead zone is easily formed around the stirring shaft of the spiral blade. The dead zone accounts for a low proportion within the pitch range of the present invention, and the spiral blade has a strong transport capacity. Within this range, as the pitch increases, the stirring movement of the material along the axial direction is more intense, the distribution is more dispersed, and the mixing uniformity is better. However, if the pitch continues to increase and exceeds the scope of the present application, it will have little effect on improving the mixing uniformity and reducing the dead zone proportion, and will reduce the mixing effect. If the pitch is lower than the scope of the present application, the mixed material forms a mixing dead zone around the stirring shaft, and it is easy to form small clusters and gather around the stirring shaft, which is not conducive to mixing.

[0033] If the gap between the top of the spiral blade and the inner wall of the mixing barrel is too large, the leakage will increase, which is not conducive to the quantitative transportation of the mixed material; if the gap is too small, the bending deformation of the continuous spiral blade and the processing and manufacturing errors will cause the blade and the inner wall of the mixing barrel to wear each other, resulting in mechanical damage, greatly increasing the power consumption of the equipment and reducing the reliability of the equipment.

[0034] In the horizontal crushing and mixing device as described above, a single auxiliary stirring blade in each group is a spiral structure, the number of spiral turns is 0.2~0.5 turns, the pitch is 400~800mm, the thickness (i.e. the dimension of the auxiliary stirring blade in the direction perpendicular to the unfolded surface of the blade) is 5~20mm, and the height (i.e. the dimension of the auxiliary stirring blade in the direction perpendicular to the central axis of the stirring shaft) is 40~100mm. The auxiliary stirring blade can stir the material in the area around the stirring shaft to prevent the formation of a mixing dead zone around the stirring shaft, and play an auxiliary supporting role for the crushing blade support rod to prevent the support rod from fatigue fracture due to stress concentration.

[0035] In the above-mentioned horizontal crushing and mixing device, at least one U-shaped groove penetrating the crushing blade is respectively provided on the top and both sides of the crushing blade; the width of the U-shaped groove is 5-30 mm, and the depth is 10-30 mm. The U-shaped groove can improve the crushing efficiency of the crushing blade, while reducing the force-bearing area and reducing power consumption; the height direction of the crushing blade is perpendicular to the central axis of the stirring shaft; the crushing blade is inclined toward the direction of the discharge rod, and the angle between the plane where the crushing blade is located and the central axis of the stirring shaft is 30°-55°, preferably 34°-42°;

[0036] After the U-shaped groove structure is added to the crushing blade, on the one hand, the edge of the U-shaped groove structure forms a new cutting edge, which is longer than the cutting edge of the new structure of the crushing blade without the U-shaped groove structure; on the other hand, the U-shaped groove structure increases the shear rate of the crushing blade on the material; with the increase in the length of the cutting edge and the increase in the shear rate, the crushing efficiency of the crushing blade on the cellulose particles after absorbing the NMMO aqueous solution is significantly improved. Among them, due to the addition of the U-shaped groove structure, the area of ​​the crushing blade is reduced (the reduced area is the area occupied by the U-shaped groove), so under the same positive pressure, the force area of ​​the crushing blade with the U-shaped groove structure is reduced.

[0037] The rationality of the installation angle of the crushing blade directly affects the uniformity and efficiency of mixing. The installation angle of the blade refers to the acute angle between the plane where the blade is located and the central axis of the stirring shaft. Under the same conditions, the smaller the installation angle of the crushing blade, the greater the speed of the material in the circumferential direction, and the corresponding axial movement speed will decrease accordingly, thus affecting the mixing uniformity. When the installation angle is 0°, that is, the plane where the crushing blade is located is parallel to the axis of the stirring shaft, then the material reciprocates in a circular motion with the stirring shaft as the center under the push of the blade, and the axial movement corresponds to the convection movement, which is the stirring and mixing of the material. The main motion is achieved, but the material has no axial speed, and a dead zone of the material will appear between the blades, affecting the uniformity of mixing, and the material cannot be discharged from the material outlet under the push of the crushing blades; when the installation angle is 90°, that is, the plane where the crushing blades are located is perpendicular to the central axis of the stirring shaft, the crushing blades only have a shearing effect on the material, and the material has neither axial speed nor circumferential speed, and the blades basically have no stirring and mixing effect on the material; the angle is set within the scope of the present invention, the material has a large speed in both the axial and circumferential directions, can produce a strong stirring and mixing effect, and achieve a higher mixing efficiency.

[0038] The formula for calculating the reasonable installation angle β is:

[0039] ;

[0040] In the formula, is the axial stirring coefficient; Fig.11 As shown, from the cross-sectional view of the top view, the mixed material 14 is accumulated on the crushing blade 9 into a triangle, and the three vertices are S1, S2, and S3, wherein the end point of the vertex is S1, and the three vertices S1, S2, and S3 are distributed clockwise, corresponding to the three vertices of the triangle respectively. It is the projected length of the side S1S2 of the triangle formed by the mixed material 14 on the crushing blade 9 on the vertical plane where the axis of the stirring shaft is located; It is the projected length of the triangular side S1S3 formed by the mixed material 14 deposited on the crushing blade 9 on the vertical plane where the axis of the stirring shaft is located; is the projection length of the base S2S3 of the triangle formed by the mixed material 14 on the crushing blade 9 on the vertical plane where the axis of the stirring shaft is located; θ is the angle between the side S1S2 of the triangle formed by the mixed material 14 on the crushing blade 9 and the axis of the stirring shaft, and the opening direction is toward the vertex S3.

[0041] ;

[0042] In the formula, is the circumferential stirring coefficient, is the accumulation cross-sectional area of ​​the mixed material on the crushing blade, It is the maximum cross-sectional area of ​​the mixed material accumulated on the crushing blade when the installation angle is 0°;

[0043] Then K S With K C The partial derivative of the installation angle β is calculated by multiplying the angle by θ and setting the formula equal to zero. Substituting the value of the angle θ, the installation angle is obtained as follows:

[0044] .

[0045] In the horizontal crushing and mixing device as described above, the number of discharge rods in each group is two, and the angle between the two discharge rods in each group is 180°; a plurality of groups of discharge rods are fixed on the stirring shaft in a manner of surrounding the stirring shaft, and two adjacent groups of discharge rods are circumferentially staggered. Compared with the discharge blades, the discharge rods reduce the force bearing area, which can prevent fatigue fracture of the blade support rods, and at the same time reduce the material and processing costs of the parts;

[0046] Among them, changing the discharge blades into discharge rods will not affect the discharge effect. In the prior art, the mixing drum of the horizontal crushing and mixing device is placed horizontally, and both ends of the mixing drum are closed. The discharge port is located on the lower side wall of the mixing drum and is close to one end face. When the cellulose pulp moves to the top of the discharge port, it will be discharged under the action of the discharge rod and gravity. Even when the cellulose pulp moves to the top of the discharge port, it still has a tendency to move horizontally, but it will be blocked by the end face so that it can only move downward; secondly, the stirring action of the discharge rod can effectively prevent the cellulose pulp from agglomerating at the discharge port. The two functions of the above-mentioned discharge rod are the same as those of the discharge blades, so it will not affect the discharge effect.

[0047] Beneficial effects:

[0048] (1) The present invention adopts a spiral pump structure formed by spiral blades and a mixing cylinder in the swelling zone, which can push the mixed material to the crushing and mixing zone in a quantitative manner, thereby accurately controlling the mixing time and ensuring the mixing efficiency and uniformity.

[0049] (2) The present invention adopts a crushing blade with a U-shaped groove in the crushing and mixing zone, which can improve the crushing efficiency and the shearing effect on the mixed materials, while reducing the force-bearing area and reducing power consumption.

[0050] (3) The present invention fixes the two side edges of the auxiliary stirring blade located in the crushing and mixing zone to the support rods of two adjacent crushing blades, and fixes the bottom edge to the stirring shaft, so that the stirring blade can stir the material in the area around the stirring shaft to prevent the formation of a mixing dead zone around the stirring shaft, and can also play an auxiliary supporting role for the crushing blade support rod to prevent the support rod from fatigue fracture due to stress concentration, thereby improving the mixing quality of the material and the reliability of the equipment.

[0051] (4) In the present invention, a soft rubber plate is fixed on the top of the segmented propeller blades in the feed zone. The material of the rubber plate is set to EPDM rubber, which can reduce the occurrence of solid material blocking events, thereby reducing power consumption and the probability of parts damage;

[0052] (5) The present invention divides the four discharge rods in the discharge area into two groups and fixes them on the stirring shaft in a manner of surrounding the stirring shaft. Each group of discharge rods includes two discharge rods. Compared with the discharge blades, the discharge rods can reduce the force-bearing area, prevent fatigue fracture of the blade support rods, and reduce the material and processing costs of the parts.

[0053] (6) The blade combination of each zone of the agitator of the crushing and mixing device of the present invention is a new type of agitator structure designed on the basis of a large number of cellulose particle swelling and stirring experiments and simulation analysis. It is a structure designed according to the different binding states and swelling stages of cellulose particles and NMMO aqueous solution, and is not a general structural improvement of the agitator of the existing mixing device. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a schematic diagram of the overall structure of the horizontal crushing and mixing device of the present invention;

[0055] Figure 2 It is a three-dimensional structural diagram of the agitator in the horizontal crushing and mixing device of the present invention;

[0056] Figure 3 It is a functional area division diagram of the horizontal crushing and mixing device of the present invention;

[0057] Figure 4 The present invention is a structural diagram of a segmented propeller blade and a soft rubber plate in a horizontal crushing and mixing device; in the figure, (a) is a three-dimensional structural diagram of the segmented propeller blade and the soft rubber plate, (b) is a front view of the segmented propeller blade and the soft rubber plate, (c) is a side view of the segmented propeller blade and the soft rubber plate, and C represents the thickness of the soft rubber plate;

[0058] Figure 5It is a front view of the spiral pump structure formed by the spiral blade and the mixing barrel in the horizontal crushing and mixing device of the present invention; in the figure, P is the pitch of the spiral blade, and δ is the gap between the top of the spiral blade and the inner wall of the mixing barrel;

[0059] Figure 6 The present invention is a structural diagram of a crushing blade in a horizontal crushing and mixing device; in the figure, (a) is a three-dimensional structural diagram of the crushing blade, (b) is a front view of the crushing blade, and (c) is a side view of the crushing blade;

[0060] Figure 7 The figure is a schematic diagram of the installation angle of the crushing blade in the horizontal crushing and mixing device of the present invention; in the figure, (a) is a front view of the installation angle of the crushing blade, and (b) is a top view of the installation angle of the crushing blade;

[0061] Figure 8 The present invention is a schematic diagram of a fixing method of the auxiliary stirring blade in the horizontal crushing and mixing device; in the figure, (a) is a three-dimensional diagram of the fixing method of the auxiliary stirring blade, (b) is a front view of the fixing method of the auxiliary stirring blade, and (c) is a side view of the fixing method of the auxiliary stirring blade;

[0062] Fig. 9 The structure diagram of the auxiliary stirring blade in the horizontal crushing and mixing device of the present invention; in the figure, (a) is a three-dimensional structure diagram of the auxiliary stirring blade, (b) is a front view of the auxiliary stirring blade, (c) is a side view of the auxiliary stirring blade, and (d) is a top view of the auxiliary stirring blade;

[0063] Fig.10 The present invention is a horizontal crushing and mixing device of the present invention. The arrangement and structure diagram of the discharge rods in the discharge area; in the figure, (a) is a three-dimensional diagram of the arrangement of the discharge rods in the discharge area, (b) is a front view of the arrangement of the discharge rods in the discharge area, and (c) is a side view of the arrangement of the discharge rods in the discharge area;

[0064] Fig.11 It is a cross-sectional view from above when the mixed material is accumulated on the surface of the crushing blade when the horizontal crushing and mixing device of the present invention is working;

[0065] Fig.12 The equivalent stress diagrams of two adjacent groups of crushing blades in the crushing and mixing zone of the horizontal crushing and mixing device of the present invention and the blades of other patents; in the figure, (a) is the equivalent stress diagram of two adjacent groups of crushing blades in the crushing and mixing zone of the present invention, (b) is the equivalent stress diagram of two adjacent groups of crushing blades in the crushing and mixing zone of patent CN115445468A, (c) is the maximum equivalent stress comparison diagram of two adjacent groups of crushing blades in the crushing and mixing zone of the present invention and the prior art, (d) is the maximum equivalent stress comparison diagram of the roots of the support rods of two adjacent groups of crushing blades in the crushing and mixing zone of the present invention and the prior art;

[0066] Fig.13 The flow field velocity distribution diagram of the crushing blade and the auxiliary stirring blade in the horizontal crushing and mixing device of the present invention when they are working; in the figure, (a) is the flow field velocity distribution diagram when the crushing blade and the auxiliary stirring blade work together, and (b) is the flow field velocity distribution diagram when the auxiliary stirring blade works;

[0067] Fig.14 It is a statistical diagram of the number of particles of different diameters newly generated by the crushing simulation of large-diameter granular materials by the crushing blades in the variable-diameter crushing and mixing device of the present invention and the blades in the prior art; in the figure, (a) is a statistical diagram of the number of particles of different diameters newly generated by the crushing simulation of the crushing blades of the present invention, and (b) is a statistical diagram of the number of particles of different diameters newly generated by the crushing simulation of the crushing blades of the prior art;

[0068] Among them, 1-cellulose particle inlet, 2-mixing cylinder, 3-cellulose porridge outlet, 4-NMMO aqueous solution inlet, 5-propeller blade support rod, 6-propeller blade, 7-soft rubber plate, 8-propeller blade, 9-crushing blade, 10-auxiliary stirring blade, 11-discharging rod, 12-stirring shaft, 13-crushing blade support rod, 14-mixing material, 15-feeding area, 16-swelling area, 17-crushing and mixing area, 18-discharging area. DETAILED DESCRIPTION

[0069] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0070] A horizontal crushing and mixing device, such as Figure 1 As shown, it includes a mixing barrel 2 and an agitator installed in the mixing barrel 2 in a coaxial manner;

[0071] The mixing cylinder 2 is a horizontally placed cylindrical cylinder;

[0072] A cellulose particle inlet 1 and an NMMO aqueous solution inlet 4 are provided near one end of the mixing cylinder 2, and a cellulose slurry outlet 3 is provided near the other end of the mixing cylinder 2;

[0073] like Figure 2 As shown, the stirrer includes a stirring shaft 12 and a plurality of propeller blades 6 fixed on the stirring shaft 12, a spiral blade 8, a plurality of groups of crushing blades 9, a plurality of groups of auxiliary stirring blades 10 and a plurality of groups of discharge rods 11;

[0074] A plurality of propeller blades 6, a propeller blade 8, a plurality of groups of crushing blades 9 and a plurality of groups of discharge rods 11 are sequentially arranged along the axial direction of the stirring shaft 12, and a plurality of groups of auxiliary stirring blades 10 are evenly arranged along the axial direction of the stirring shaft 12 between the propeller blade 8 and the discharge rod 11;

[0075] like Figure 2 , Figure 4 As shown, the bottom of each propeller blade 6 is connected to a propeller blade support rod 5, and a plurality of propeller blades 6 are fixed to the stirring shaft 12 through the propeller blade support rod 5 and are arranged in a segmented spiral;

[0076] A soft rubber plate 7 is arranged on the top of each propeller blade 6. The material of the soft rubber plate 7 is EPDM rubber. The thickness of the soft rubber plate 7 is 5-10 mm, and the hardness at room temperature is 60-75 Shore A.

[0077] The spacing between two adjacent propeller blades 6 is 40-180 mm; the spiral arrangement of the plurality of propeller blades 6 is left-handed, and the pitch is 100-300 mm;

[0078] like Figure 2 , 5 As shown, the spiral blade 8 is directly fixed on the stirring shaft 12; the rotation direction of the spiral blade 8 is consistent with the rotation direction of the spirally arranged propeller blades 6; the pitch P of the spiral blade 8 is 100-300 mm, and the gap δ between the top of the spiral blade 8 and the inner wall of the mixing barrel 2 is 1-15 mm;

[0079] like Figure 2 , Figure 6~Figure 8 As shown, at least one U-shaped groove penetrating the crushing blade 9 is respectively provided on the top and both sides of the crushing blade 9; the width E of the U-shaped groove is 5-30 mm, and the depth F is 10-30 mm;

[0080] The number of each group of crushing blades 9 is more than 3, and each group of crushing blades 9 is evenly arranged around the stirring shaft 12. The bottom of each crushing blade 9 is connected to a crushing blade support rod 13, which is fixed to the stirring shaft 12 through the crushing blade 9 support rod, and two adjacent groups of blades are staggered.

[0081] The height direction of the crushing blade 9 is perpendicular to the central axis of the stirring shaft 12; the crushing blade 9 is inclined toward the discharge rod 11, and the angle β between the plane where the crushing blade 9 is located and the central axis of the stirring shaft 12 is 30°~55°;

[0082] like Fig. 9 As shown, a single auxiliary stirring blade 10 in each group is a spiral structure, the number of spiral turns is 0.2-0.5 turns, the pitch G is 400-800 mm, the thickness W is 5-20 mm, and the height H is 40-100 mm;

[0083] The number of each group of auxiliary stirring blades 10 is at least 3, and each group of auxiliary stirring blades 10 is evenly arranged around the stirring shaft 12. Both sides of each auxiliary stirring blade 10 are fixedly connected to one crushing blade support rod 13 of each of the two adjacent groups, and the bottom side is fixedly connected to the stirring shaft 12;

[0084] like Fig.10 As shown, the discharge rod 11 is directly fixed on the stirring shaft 12;

[0085] There are two discharge rods 11 in each group, and the angle between the two discharge rods 11 in each group is 180°; several groups of discharge rods 11 are fixed on the stirring shaft 12 in a manner of surrounding the stirring shaft 12, and two adjacent groups of discharge rods 11 are circumferentially staggered.

[0086] In order to verify the mixing effect of the above-mentioned device on cellulose particles and NMMO aqueous solution, the above-mentioned horizontal crushing and mixing device is used to mix cellulose particles and NMMO aqueous solution, wherein the soft rubber plate (made of EPDM rubber, manufactured by Nanjing Gubai Rubber & Plastic Products Co., Ltd., with a brand name of GB0103) has a thickness of 10 mm and a hardness of 70 Shore A at room temperature; the spacing between two adjacent propeller blades is 40 mm, and the pitch of the propeller blades is 300 mm; the pitch P of the spiral blades is 300 mm, and the gap δ between the top of the spiral blades and the inner wall of the mixing barrel is 5 mm; three U-shaped grooves are respectively provided on the top and both sides of the crushing blade, starting from the point where the crushing blade support rod is fixedly connected to the crushing blade, the widths E of the U-shaped grooves on the top and both sides of the crushing blade in a clockwise direction are 15 mm, 15 mm, 15 mm, 15 mm, and 20 mm respectively. , 15mm, 15mm, 15mm, 15mm, the depth F is 10mm, 10mm, 10mm, 20mm, 20mm, 20mm, 10mm, 10mm, 10mm, the number of crushing blades in each group is 3, and the angle β between the plane where the crushing blades are located and the central axis of the stirring shaft is 45°; the number of auxiliary stirring blades in each group is 3, the number of spiral turns of the auxiliary stirring blade is 0.2 turns, the pitch G is 510mm, the thickness W is 8mm, and the height H is 65mm;

[0087] First, the outer wall of the mixing drum of the horizontal crushing and mixing device is heated to 75°C in a water bath, and the speed of the agitator is set to 122 rpm. Then, cellulose particles and NMMO aqueous solution with a mass ratio of 11.4:88.6 (the mass ratio of NMMO to water is 67.9:20.7) are respectively introduced into the mixing drum through the cellulose particle inlet and the NMMO aqueous solution inlet. The cellulose particles move toward the swelling zone under the push of the segmented propeller blades. After reaching the swelling zone, the cellulose particles are preliminarily swollen with the NMMO aqueous solution. Then, the preliminarily swollen cellulose particles are transported to the mixing drum through the spiral pump structure formed by the spiral blades and the mixing drum. To the crushing and mixing zone, the cellulose particles are gradually crushed into powdery cellulose particles under the continuous beating and shearing action of the crushing blades with U-shaped grooves, and are uniformly mixed with the NMMO aqueous solution under the continuous stirring of the auxiliary stirring blades to form cellulose pulp. Since the crushing blades are installed at a certain angle to the axis of the stirring shaft, the crushing blades push the cellulose particles and the NMMO aqueous solution at a relatively high speed in the axial and circumferential directions, thereby generating a strong stirring and mixing effect, and under the action of the axial speed, the cellulose particles and the NMMO aqueous solution move to the discharge zone. In the discharge zone, the cellulose pulp formed by the uniform mixing under the continuous stirring of the staggered discharge rods is discharged from the material outlet.

[0088] The mixed cellulose pulp porridge was taken out from the cellulose pulp porridge prepared as above by a sampler as a sample, and then 2.5 g of the sample was weighed into a 250 ml beaker, and 200 ml of boiling distilled water was added. The cellulose pulp porridge was stirred evenly and placed on a heated magnetic stirrer (C-MAG HS 10 model), boiled for 10 minutes, filtered with a G2 sand core crucible, and then repeatedly rinsed with 400 ml of hot distilled water at a temperature of 75°C until there was no NMMO content, placed in a drying oven (PH-070A model) for drying for 15 minutes, taken out and cooled for 15 minutes and weighed, and the above steps were repeated 5 times. The average weight was calculated as the cellulose content. Finally, it was compared with the theoretical weight and it was found that the weight difference between the two was very small, indicating that the solid content of the cellulose pulp porridge was uniform, that is, the cellulose pulp porridge was of high quality.

[0089] Repeat the above steps 5 times, calculate the average weight (i.e. the cellulose content), and finally compare it with the theoretical weight (theoretical weight is 11.4%). It is found that the difference between the two weights is very small, indicating that the solid content of the cellulose pulp porridge is uniform, that is, the cellulose pulp porridge is of high quality.

[0090] In order to verify the crushing efficiency of the above-mentioned device for cellulose particles and NMMO aqueous solution, the DEM simulation software is now used to simulate and compare the crushing efficiency of the crushing blades and auxiliary stirring blades with U-shaped grooves in the present invention and the blades in the prior art (patent CN115445468A); the Bonding key model and the Tavares model are mainly used to simulate the solid particle crushing process. The Tavares crushing model uses the particle fracture energy theory to describe the particle crushing process. The model is described by mathematical expressions. When the impact energy of the particle exceeds its own fracture energy, the larger diameter particle will be broken into smaller diameter particles, thereby simulating the entire process of solid particle crushing. The present invention uses the Tavares crushing model, and the mathematical expression of the Tavares crushing model is described as follows:

[0091] Each particle has a specific fracture energy, which is distributed according to its size, mean value and standard deviation. The distribution formula of particle fracture energy is:

[0092] ;

[0093] ;

[0094] Where: is the fracture probability, E is the particle fracture energy distribution, corresponding to the energy of the maximum stress it can withstand in a collision, is the upper cutoff value of the distribution, is the median of the distribution; is the standard deviation of the distribution;

[0095] The formula for the median specific fracture energy of a particle is:

[0096] ;

[0097] In the formula, 、d0、 Fit the model parameters to the experimental data, is the representative particle size contained in the particle size grade, is the particle size, is the surface stiffness of the material in contact with the particle, is the stiffness of the granular material;

[0098] In the case where the particle does not break, it will be damaged, and then the particle will have a new fracture energy, which is lower than the previous fracture energy. This new fracture energy will be an inherent property of the particle until the next damage event occurs. The formula for the fracture energy of the particle is:

[0099] ;

[0100] ;

[0101] In the formula, E f is the fracture energy of the particle, D is the damage variable, eE k is the specific stress energy (or effective impact energy) involved in the collision, γ is the damage accumulation coefficient, which characterizes the adaptability of the material to sustain damage before penetrating fracture, and e is the energy ratio involved in the collision, which is allocated to different types of particles according to the stiffness of the particles;

[0102] The formula for the collision energy ratio e is:

[0103] ;

[0104] Stress energy E k is given by the combination of normal energy and tangential energy, and its formula is:

[0105] ;

[0106] In the formula, E n is the normal energy, E t is the tangential energy, c t It is the proportion of tangential energy that contributes to the collision energy.

[0107] The degree of particle fragmentation can be described by a single parameter t 10 It is expressed as the mass percentage of particles of different diameters newly generated after crushing that are smaller than 1 / 10 of the particle size before crushing. 10 It can be calculated by the median of the specific stress energy and particle fracture energy, and its expression is:

[0108] ;

[0109] Where A is the maximum particle size that can be achieved when the particle is broken in a single impact. 10 The maximum value of; b is the hardness parameter of the particles.

[0110] First, the initial diameter of the solid particle material is set to Φ25mm, and the minimum diameter of the newly generated particles after crushing is Φ5mm. The Tavares crushing mathematical model is used to simulate the crushing of the crushing blade with U-shaped groove and the blade of the prior art under the same operating conditions in the DEM simulation software;

[0111] The crushing simulation results are as follows Fig.14As shown in the figure, it can be seen that under the same conditions, the number of newly generated particles of different diameters in the horizontal crushing and mixing device of the present invention is greater than that of the blades of the prior art. Taking the total number of newly generated particles of the smallest diameter in the first row as an example, the total number of newly generated particles of this diameter in the horizontal crushing and mixing device of the present invention is 1318, while the total number of newly generated particles of this diameter in the prior art device is 786; therefore, the crushing efficiency of the crushing blades in the horizontal variable diameter crushing and mixing device of the present invention is better than that of the prior art structure.

[0112] ANSYS Workbench software is used to simulate the equivalent stress of two adjacent groups of crushing blades in the horizontal crushing and mixing device of the present invention and two adjacent groups of blades in the prior art (patent CN115445468A). Fig.12 As shown in the figure, it can be seen that under the same working conditions, due to the supporting effect of the auxiliary stirring blade on the crushing blade support rod, the overall maximum equivalent stress of the crushing blade and its support rod of the horizontal crushing and mixing device of the present invention is reduced by 25% compared with the equivalent stress of the blades of other patent structures, and the maximum stress at the root of the crushing blade support rod is reduced by 200%. Therefore, fatigue fracture of the crushing blade support rod can be effectively prevented, and the reliability of the equipment is improved.

[0113] Fluent fluid software is used to simulate the flow field velocity distribution when the crushing blade and the auxiliary stirring blade in the horizontal crushing and mixing device of the present invention are working. Fig.13 As shown in the figure, it can be seen that the crushing blade plays a major stirring role in the mixed material, the auxiliary stirring blade plays an auxiliary stirring role in the mixed material, and the auxiliary stirring blade has an enhancing effect on the flow velocity of the material around the stirring shaft, which can reduce the volume proportion of the mixing dead zone around the stirring shaft.

Claims

1. A horizontal crushing and mixing device, comprising a mixing drum and an agitator coaxially mounted in the mixing drum, characterized in that: The agitator comprises a stirring shaft and a plurality of propeller blades, a spiral blade, a plurality of groups of crushing blades, a plurality of groups of auxiliary stirring blades and a plurality of groups of discharge rods fixed on the stirring shaft, wherein the plurality of propeller blades, the spiral blade, the plurality of groups of crushing blades and the plurality of groups of discharge rods are sequentially arranged along the axial direction of the stirring shaft, and the plurality of groups of auxiliary stirring blades are evenly arranged between the spiral blade and the discharge rod along the axial direction of the stirring shaft; The bottom of each propeller blade is connected to a propeller blade support rod, and a plurality of propeller blades are fixed on the stirring shaft through the propeller blade support rod and are arranged in a segmented spiral; The spiral blades are directly fixed on the stirring shaft; The number of each group of crushing blades is more than 3, and each group of crushing blades is evenly arranged around the stirring shaft. The bottom of each crushing blade is connected to a crushing blade support rod, which is fixed to the stirring shaft through the crushing blade support rod; The number of each group of auxiliary stirring blades is at least 3, and each group of auxiliary stirring blades is evenly arranged around the stirring shaft. Both sides of each auxiliary stirring blade are fixedly connected to the support rods of two adjacent groups of crushing blades, and the bottom edge is fixedly connected to the stirring shaft. The discharge rod is directly fixed on the stirring shaft; The gap between the top of the spiral blade and the inner wall of the mixing cylinder is ≤15mm.

2. A horizontal crushing and mixing device according to claim 1, characterized in that: A soft rubber plate is arranged on the top of each propeller blade. The material of the soft rubber plate is EPDM rubber. The thickness of the soft rubber plate is 5-10 mm and the hardness is 60-75 Shore A at room temperature.

3. A horizontal crushing and mixing device according to claim 2, characterized in that: The spacing between two adjacent propeller blades is 40~180mm; the rotation direction of several spirally arranged propeller blades is left-handed, which is consistent with the rotation direction of the spiral blade, and the pitch is 100~300mm.

4. A horizontal crushing and mixing device according to claim 3, characterized in that: The pitch of the spiral blade is 100~300mm, and the gap between the top of the spiral blade and the inner wall of the mixing cylinder is 1~15mm.

5. A horizontal crushing and mixing device according to claim 4, characterized in that: The single auxiliary stirring blade in each group is a spiral structure, with the number of spiral turns being 0.2 to 0.5, the pitch being 400 to 800 mm, the thickness being 5 to 20 mm, and the height being 40 to 100 mm.

6. A horizontal crushing and mixing device according to claim 5, characterized in that: There is at least one U-shaped groove penetrating the crushing blade on the top and both sides of the crushing blade; the width of the U-shaped groove is 5~30mm and the depth is 10~30mm; the height direction of the crushing blade is perpendicular to the central axis of the stirring shaft; the crushing blade is inclined toward the discharge rod, and the angle between the plane where the crushing blade is located and the central axis of the stirring shaft is 30°~55°.

7. A horizontal crushing and mixing device according to claim 1, characterized in that: There are two discharge rods in each group, and the angle between the two discharge rods in each group is 180°; several groups of discharge rods are fixed on the stirring shaft in a manner of surrounding the stirring shaft, and two adjacent groups of discharge rods are circumferentially staggered.

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