Distributed drive vertical roller mill and its grinding process

Abstract

The present application belongs to vertical roller mill equipment technical field, especially related to distributed drive vertical roller mill and its grinding process, the distributed drive vertical roller mill includes the grinding roller arranged on the grinding disc, the grinding disc is driven by the main motor, the grinding roller is equipped with the planetary transmission system, and is driven by the grinding roller motor through the transmission shaft installed in the roller shaft, the roller shaft end is equipped with the shaft end cover, the inner wall of the shaft end cover is equipped with the inner ring gear, the end of the transmission shaft is equipped with the sun gear, the inner ring gear is engaged with the planetary gear, the planetary gear is engaged with the sun gear, the planetary gear is installed on the planetary gear pin shaft, the planetary gear pin shaft is installed on the planet carrier, and the planet carrier is fixed with the wheel hub. The present application provides a kind of to solve the bottleneck of large-scale drive system of vertical mill, improve the efficiency of grinding, the adaptability of grinding a variety of materials distributed drive vertical roller mill and its grinding process.

Description

Technical Field

[0001] This invention belongs to the technical field of vertical roller mill equipment, and particularly relates to a distributed drive vertical roller mill and its grinding process. Background Technology

[0002] Existing technology:

[0003] The existing drive system of vertical roller mills includes an asynchronous motor and a reducer. The grinding disc rotates actively, while the grinding rollers rotate passively. The grinding rollers rotate slower than the grinding disc, which causes material to accumulate at the front end of the rollers, resulting in an unstable material bed and reduced grinding efficiency. The maximum power of the reducer can reach 8000KW. The manufacturing difficulty and cost of reducers with higher power are enormous, becoming a bottleneck restricting the large-scale development of vertical roller mills.

[0004] With the increasing demand for larger, lower-energy-consumption vertical mills and the processing of a wider variety of materials, simply increasing the mill's size and power is no longer sufficient. Adjustable and precisely controllable grinding disc speed is also crucial. Due to the significantly increased power of the motors in larger mills, the required frequency converters are difficult to manufacture, making the drive system for vertical mills economically impractical. Existing technology CN114618648A discloses a method where the grinding rollers are driven by a separate motor, which directly drives the grinding rollers via a rotating shaft located within the grinding roller shaft. However, because the rotating shaft's speed is relatively low, the power of the grinding roller motor cannot exceed 700 kW; otherwise, the diameter of the rotating shaft would need to be increased, requiring larger grinding roller bearings, resulting in a high cost for the grinding roller drive device.

[0005] The difficulty and significance of solving the above technical problems:

[0006] Therefore, based on these issues, providing a distributed-drive vertical roller mill and its grinding process to solve the bottleneck of the large-scale vertical mill drive system, improve grinding efficiency, and adapt to grinding various materials has important practical value. Summary of the Invention

[0007] The purpose of this application is to provide a distributed-drive vertical roller mill and its grinding process that solves the bottleneck of the large-scale drive system of vertical mills, improves grinding efficiency, and is adaptable to grinding a variety of materials, in order to solve the technical problems in the prior art.

[0008] The technical solution adopted in this application embodiment to solve the technical problems existing in the prior art is as follows:

[0009] A distributed-drive vertical roller mill includes grinding rollers mounted on a grinding disc, the grinding disc being driven by a main motor, a planetary transmission system within the grinding rollers being driven by a grinding roller motor via a transmission shaft installed within the roller shaft, a shaft end cap at the end of the roller shaft, an internal gear ring on the inner wall of the shaft end cap, a sun gear at the end of the transmission shaft, the internal gear ring meshing with planet gears, the planet gears meshing with the sun gear, the planet gears being mounted on planet gear pins, the planet gear pins being mounted on planet carriers, and the planet carriers being fixed to the hubs.

[0010] The embodiments of this application may also employ the following technical solutions:

[0011] In the aforementioned distributed drive vertical roller mill, a bearing is further provided between the shaft end cover and the drive shaft, and a planetary bearing is provided between the planetary gear and the planetary gear pin. The planetary bearing is a sliding bearing.

[0012] In the aforementioned distributed drive vertical roller mill, the drive system of the planetary transmission system further includes a grinding roller motor, a universal coupling, a right-angle shaft reducer, a coupling, and a drive shaft connected in sequence. The end of the drive shaft is connected to the planetary transmission system. The right-angle shaft reducer is mounted on a reducer support at the rear end of the upper rocker arm. The grinding roller motor is mounted on a motor support, which is a concrete or steel structure.

[0013] In the above-mentioned distributed drive vertical roller mill, the outer side of the hub is fixed with a roller sleeve, a grinding roller bearing is provided between the hub and the roller shaft, the roller shaft is fixed in the upper rocker arm by an expansion sleeve, the roller shaft is a hollow shaft structure and only bears bending moment, and the transmission shaft is fixed in the roller shaft by a bearing and only bears torque.

[0014] In the above-mentioned distributed drive vertical roller mill, the number of grinding rollers is three to six, and the center line of the grinding roller motor is arranged at 90° with the center line of the grinding roller.

[0015] In the aforementioned distributed-drive vertical roller mill, the main motor, diaphragm coupling, and main reducer are connected in sequence, and the main motor is a variable frequency motor.

[0016] In the aforementioned distributed-drive vertical roller mill, the pressurizing device further includes a hydraulic cylinder mounted on a support, which drives a lower rocker arm, and the lower rocker arm is connected to the upper rocker arm via a rocker arm shaft.

[0017] In the aforementioned distributed-drive vertical roller mill, a vibrating feeder is further provided above the grinding disc, and a nozzle ring is provided at the edge of the grinding disc. The nozzle ring, air duct, and slag discharge port are connected in sequence.

[0018] A grinding process using a distributed-drive vertical roller mill, wherein the distributed-drive vertical roller mill grinding process employs any of the above-described distributed-drive vertical roller mills, and the grinding process includes the following steps:

[0019] The material falls into the center of the grinding disc through the vibrating feeder. Both the grinding roller and the grinding disc are active rotating parts. The material falling into the center of the grinding disc moves towards the edge of the grinding disc under the action of the centrifugal force of the rotating grinding disc. Each grinding roller rotates actively under an independent and controllable drive system and crushes the material on the grinding disc under the action of the hydraulic cylinder.

[0020] The material is subjected to the squeezing and shearing forces of the grinding rollers on the grinding disc. The crushed material falls into the nozzle ring and is transported to the top of the grinding disc by airflow to form a rotating suspension layer. Coarse particles fall onto the grinding disc for further grinding, while the material falling into the air duct is discharged through the slag discharge port and then lifted by the elevator to re-enter the mill. Small particles are transported by airflow to the classifier for separation and discharge, while the rest return to the grinding disc for further grinding.

[0021] One or more technical solutions provided in the embodiments of this application have at least the following beneficial effects:

[0022] 1. This invention incorporates a planetary transmission system, resulting in a significantly higher rotational speed of the transmission shaft. When the planetary speed ratio is approximately four, the transmission speed increases fourfold, the transmission torque decreases fourfold, and the diameter can be smaller. With the same grinding roller shaft diameter, the power of the grinding roller motor can be doubled, reaching 1500-2000 kW. The overall installed power of the mill can also be more than doubled. This addresses the limitations of existing technology where the maximum grinding roller motor power is 700 kW. Exceeding this maximum value leads to unreliable motor installation, increased shaft diameter requiring larger grinding roller bearings, and higher costs for the grinding roller drive system.

[0023] 2. The orthogonal shaft reducer of the present invention is located outside the mill, and the planetary transmission system is located inside the mill. The two are connected by a transmission shaft, which is located inside the roller shaft. The sun gear is located at the end of the transmission shaft, the planet carrier is connected to the hub, and the internal gear ring is fixed. This configuration can minimize the outer diameter of the transmission shaft, thereby reducing the size of the roller shaft, grinding roller bearing, and upper rocker arm. This makes the grinding roller drive device more economical.

[0024] 3. This invention has multiple independent and controllable drive systems, which can realize their respective control functions relatively independently, solve the bottleneck of the drive system for large-scale vertical mills, improve grinding efficiency, adaptability to grinding various materials, increase mill output and reduce power consumption.

[0025] Meanwhile, each grinding roller is driven by a separate motor through a reduction gear system, and the grinding disc is also driven by a separate motor, both rotating actively. The speeds of both can be precisely controlled by a frequency converter, ensuring optimal operating conditions for different materials and improving the flexibility and performance of the equipment.

[0026] 4. Compared with the existing technology where vertical mills are driven by a single main motor and the grinding rollers are passively rotated without being driven, this invention uses several motors instead of a single main motor. The installed power of the mill is distributed to each grinding roller and grinding disc. The total power remains unchanged, but the power of a single motor and the torque of the reducer are reduced, making it easier to use a frequency converter for precise control.

[0027] 5. This invention has better material biting capability. The material is actively bitten into the grinding zone by the rotation of the grinding disc and rollers, improving the stability of the material on the grinding disc and reducing mill vibration. Higher roller pressure can be used, with the projected pressure increasing by approximately 20% compared to the previous version, improving grinding efficiency and reducing power consumption.

[0028] 6. This invention provides a distributed-drive vertical roller mill and its grinding process. The grinding roller rotates at a higher speed than the grinding disc, has a stronger feeding capacity, and there is no material accumulation at the front end of its grinding zone. The material bed has good stability, and the material is subjected to higher extrusion and shear forces in the grinding zone. Compared with conventional vertical mills, the stability, grinding pressure, and grinding efficiency of the mill are significantly improved, increasing the mill's output and reducing power consumption. Attached Figure Description

[0029] The technical solutions of the embodiments of this application will be further described in detail below with reference to the accompanying drawings. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of this application. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0030] Figure 1 This is a schematic diagram of the distributed drive vertical roller mill of the present invention;

[0031] Figure 2 This is a top view of a distributed-drive vertical roller mill with a three-roll design;

[0032] Figure 3 This is a cross-sectional view of the grinding roller.

[0033] In the picture:

[0034] 1. Main motor; 2. Diaphragm coupling; 3. Main reducer; 4. Vibrating feeder; 5. Grinding disc; 6. Air duct; 7. Slag discharge port; 8. Support; 9. Hydraulic cylinder; 10. Lower rocker arm; 11. Roller sleeve; 12. Nozzle ring; 13. Rocker arm shaft; 14. Upper rocker arm; 15. Reducer support; 16. Coupling; 17. Right-angle shaft reducer; 18. Motor support; 19. Grinding roller motor; 20. Universal coupling; 21. Drive shaft; 22. Roller shaft; 23. Expansion sleeve; 24. Grinding roller bearing; 25. Hub; 26. Planetary carrier; 27. Bearing; 28. Sun gear; 29. ​​Planetary gear; 30. Planetary gear bearing; 31. Planetary gear pin; 32. Shaft end cover; 32a. Internal gear ring. Detailed Implementation

[0035] The distributed-drive vertical roller mill includes grinding rollers, a grinding roller drive system, a pressurizing device, a grinding disc, and a grinding disc drive system. The grinding rollers include, from the outside to the inside, a roller sleeve 11, a hub 25, a grinding roller bearing 24, and a roller shaft 22, which are fixedly arranged sequentially. The roller shaft 22 is fixed inside the upper rocker arm 14 by an expansion sleeve 23. The grinding roller drive system includes a grinding roller motor 19, a universal coupling 20, a right-angle shaft reducer 17, and a coupling 16 located outside the mill, and a planetary transmission system and a drive shaft 21 located inside the mill. The pulling force of the hydraulic cylinder 9 in the pressurizing device is transmitted to the material on the grinding disc 5 and the grinding disc 5 through the bracket 8, lower rocker arm 10, upper rocker arm 14, roller shaft 22, and roller sleeve 11. The grinding disc drive system includes a main motor 1, a diaphragm coupling 2, and a main reducer 3.

[0036] The distributed-drive vertical roller mill grinding process includes the following steps: Material falls into the center of the grinding disc 5 via a vibrating feeder 4. Both the grinding rollers and the grinding disc 5 are actively rotating components. The material falling into the center of the grinding disc moves towards the edge of the disc under the centrifugal force of the rotating disc. Each grinding roller rotates actively under an independent and controllable drive system and crushes the material on the grinding disc 5 under the force of the hydraulic cylinder 9. The grinding rollers rotate at a relatively faster speed than the grinding disc, improving the slippage between different material layers. The grinding rollers have a strong feeding capacity, and there is no material accumulation at the front end of their grinding zone, resulting in good material bed stability. The material experiences higher extrusion and shear forces in the grinding zone. The material is subjected to extrusion and shear forces from the grinding rollers on the grinding disc 5. The crushed material falls into the nozzle ring 12 and is transported by airflow to the top of the grinding disc 5, forming a rotating suspension layer. Coarse particles fall onto the grinding disc 5 for further grinding. Material falling into the air duct 6 is discharged through the slag discharge port 7 and then lifted by an elevator before re-entering the mill. Small particles are then transported by airflow to the classifier for separation and discharge, while the rest are returned to grinding disc 5 for further grinding.

[0037] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.

[0038] Example 1

[0039] The grinding rollers are evenly arranged on the grinding disc 5, with three to six rollers in total. A grinding roller motor 19 is located behind each grinding roller, and the grinding disc 5 is equipped with a main motor 1. The vertical mill has been modified from a single main motor to a combination of several motors, reducing the manufacturing difficulty of the motors, reducers, and frequency converters. If a drive system malfunctions, the mill can continue production partially, improving the equipment's operating rate.

[0040] The main reducer 1 accounts for 30-50% of the total installed power. The main motor 1 and the main reducer 3 are connected by a diaphragm coupling 2. The main motor 1 is a variable frequency motor, and the rotational speed of the grinding disc 5 is precisely controlled by a frequency converter, setting the optimal grinding disc speed for different materials. This facilitates accurate positioning during grinding disc maintenance and the welding of the grinding disc liner, and eliminates the need for traditional auxiliary transmission devices, including auxiliary transmission motors and auxiliary transmission reducers, thus reducing equipment costs.

[0041] The power of the grinding roller motor 19 accounts for 50-70% of the total installed power. Each grinding roller motor 19 has the same power and speed, and all are variable frequency motors. The linear velocity of the grinding roller in the grinding zone is greater than or equal to the linear velocity of the grinding disc. The grinding roller rotates actively, and the material is actively bitten into the grinding zone. For different materials, the optimal operating state can be achieved by adjusting parameters such as speed, current, and power.

[0042] The grinding roller motor 19 is connected to the right-angle shaft reducer 17 via a universal coupling 20. The grinding roller motor 19 is fixed on a motor support 18, which is a concrete or steel structure. The right-angle shaft reducer 17 is fixed to the rear end of the upper rocker arm 14 via a reducer support 15. The centerline of the grinding roller motor 19 is arranged at 90° to the centerline of the grinding roller for easy installation and maintenance. The universal coupling 20 transmits rotational motion and can be adjusted radially and axially to compensate for fluctuations during the operation of the grinding roller.

[0043] The roller sleeve 11 is fixed to the outside of the hub 25. A grinding roller bearing 24 is provided between the hub 25 and the roller shaft 22. The roller shaft 22 is fixed inside the upper rocker arm 14 by an expansion sleeve 23. The roller shaft 22 is a hollow shaft structure and only bears bending moment; the drive shaft 21 is fixed inside the roller shaft by a bearing and only bears torque. This configuration allows the grinding roller motor located outside the mill to drive the hub to rotate through the drive shaft inside the roller shaft, thus realizing the active rotation of the grinding roller.

[0044] The right-angle shaft reducer 17 is connected to the drive shaft 21 via a coupling 16. The end of the drive shaft 21 is connected to the planetary transmission system, thereby driving the hub 25 to rotate. The right-angle shaft reducer 17 is located outside the mill, while the planetary transmission system is located inside the mill. This configuration allows for a smaller outer diameter of the drive shaft, resulting in smaller specifications for the roller shaft, grinding roller bearings, and upper rocker arm. This configuration makes the grinding roller drive device more economical.

[0045] In the planetary transmission system, the sun gear 28 is located at the end of the transmission shaft 21, and the end of the roller shaft 22 is provided with a shaft end cover 32. The shaft end cover 32 is provided with a bearing 27 for fixing the transmission shaft 21. The shaft end cover 32 is provided with an internal gear ring 32a, which is fixed in place.

[0046] The planetary carrier is a one-piece structure. The planetary carrier 26 is equipped with three evenly distributed planetary gear pins 31. Planetary gears 29 are mounted to the planetary gear pins 31 via planetary gear bearings 30, which are sliding bearings. An internal gear ring 32a within the shaft end cover 32 simultaneously meshes with all three planetary gears 29, and a sun gear 28 simultaneously meshes with all three planetary gears 29. The planetary carrier 26 rotates relative to the roller shaft 22, and the planetary carrier 26 and the sun gear 28 have the same direction of rotation. One end of the planetary carrier 26 is fixedly connected to the hub 25, thereby transmitting rotation and torque.

[0047] The hydraulic cylinder in the pressurizing device transmits its pulling force to the material on the grinding disc 5 and the grinding disc 5 through the bracket 8, lower rocker arm 10, upper rocker arm 14, roller shaft 22, and roller sleeve 11. The pulling force of the hydraulic cylinder 9 causes the grinding roller to rotate around the rocker arm shaft 13, thus compacting and grinding the material on the grinding disc 5. By using two hydraulic cylinders to apply pressure simultaneously, the upper rocker arm 14 can rotate around the rocker arm shaft 13 and can be flipped out from the lower rocker arm 10, facilitating the installation and maintenance of the grinding roller.

[0048] Example 2

[0049] The distributed-drive vertical roller mill grinding process includes the following steps: Material falls into the center of the grinding disc via a vibrating feeder 4. Both the grinding rollers and the grinding disc are actively rotating components. The material is actively bitten into the grinding area, where it is subjected to the squeezing and shearing forces of the grinding rollers. The pulverized material falls into the nozzle ring and is transported by airflow to form a rotating suspension layer above the grinding disc. Coarse particles fall onto the grinding disc for further grinding, while material falling into the air duct is discharged through the slag discharge port and then lifted by an elevator before re-entering the mill. Small particles are further transported by airflow to a classifier for separation and discharge, while the remainder returns to the grinding disc for further grinding. The grinding rollers rotate at a relatively higher speed than the grinding disc, improving the slippage between different material layers. The grinding rollers have a strong feeding capacity, and there is no material accumulation at the front end of the grinding area, resulting in good material bed stability and high grinding efficiency.

[0050] In summary, this invention provides a distributed-drive vertical roller mill and its grinding process that solves the bottleneck of large-scale vertical mill drive systems, improves grinding efficiency, and enhances adaptability to grinding various materials.

[0051] The above embodiments have provided a detailed description of the present invention, but the content described is only a preferred embodiment of the present invention and should not be considered as limiting the scope of the present invention. All equivalent variations and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A distributed-drive vertical roller mill, characterized in that: The distributed-drive vertical roller mill includes grinding rollers mounted on a grinding disc with the roller shafts arranged at an angle. The grinding disc is driven by a main motor. Each grinding roller is equipped with a planetary transmission system, which is driven by the grinding roller motor via a transmission shaft installed within the roller shaft. The planetary transmission system includes, in sequence, a grinding roller motor, a universal coupling, a right-angle shaft reducer, a coupling, and a transmission shaft. The end of the transmission shaft is connected to the planetary transmission system. The right-angle shaft reducer is mounted on a reducer support at the rear end of the upper rocker arm. The grinding roller motor is mounted on a motor support, which is made of concrete. The roller shaft is constructed of earth or steel. No bearing is installed inside the roller shaft end. A shaft end cover is provided at the roller shaft end. A bearing is installed between the shaft end cover and the drive shaft. An internal gear ring is provided on the inner wall of the shaft end cover. A sun gear is provided at the end of the drive shaft. The internal gear ring meshes with planet gears, and the planet gears mesh with the sun gear. The planet gears are mounted on planet gear pins. A planet gear bearing, which is a sliding bearing, is provided between the planet gears and the planet gear pins. The planet gear pins are mounted on a planet carrier, and the planet carrier is fixed to the hub. The planetary transmission ratio is approximately four. The hub is externally fixed with a roller sleeve, and a grinding roller bearing is provided between the hub and the roller shaft. The roller shaft is fixed inside the upper rocker arm by an expansion sleeve. The roller shaft is a hollow shaft structure and only bears bending moment. The transmission shaft is fixed inside the roller shaft by a bearing and only bears torque.

2. The distributed drive vertical roller mill according to claim 1, characterized in that: The number of grinding rollers is three to six, and the center line of the grinding roller motor is arranged at 90° with the center line of the grinding roller.

3. The distributed drive vertical roller mill according to claim 1, characterized in that: The main motor, diaphragm coupling, and main reducer are connected in sequence, and the main motor is a variable frequency motor.

4. The distributed drive vertical roller mill according to claim 1, characterized in that: The pressurization device includes a hydraulic cylinder mounted on a bracket. The hydraulic cylinder drives a lower rocker arm, which is connected to the upper rocker arm via a rocker arm shaft.

5. The distributed drive vertical roller mill according to claim 1, characterized in that: A vibrating feeder is provided above the grinding disc, and a nozzle ring is provided at the edge of the grinding disc. The nozzle ring, air duct and slag discharge port are connected in sequence.

6. The grinding process of a distributed-drive vertical roller mill, characterized in that: The grinding process of the distributed-drive vertical roller mill adopts the distributed-drive vertical roller mill as described in any one of claims 1-5, and the grinding process of the distributed-drive vertical roller mill includes the following steps: The material falls into the center of the grinding disc through the vibrating feeder. Both the grinding roller and the grinding disc are active rotating parts. The material falling into the center of the grinding disc moves towards the edge of the grinding disc under the action of the centrifugal force of the rotating grinding disc. Each grinding roller rotates actively under an independent and controllable drive system and crushes the material on the grinding disc under the action of the hydraulic cylinder. The material is subjected to the squeezing and shearing forces of the grinding rollers on the grinding disc. The crushed material falls into the nozzle ring and is transported to the top of the grinding disc by airflow to form a rotating suspension layer. Coarse particles fall onto the grinding disc for further grinding, while the material falling into the air duct is discharged through the slag discharge port and then lifted by the elevator to re-enter the mill. Small particles are transported by airflow to the classifier for separation and discharge, while the rest return to the grinding disc for further grinding.

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