Coal pulverizing sieve with controllable mesh number
By introducing a variable frequency motor to drive the impeller and a closed-loop control system into the pulverized coal screen, the impeller speed can be dynamically adjusted, solving the problem of difficult control of coal powder particle size in traditional pulverized coal screens and improving equipment efficiency and output.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- ANYANG YONGXING IRON & STEEL CO LTD OF JIANGSUSHAGANG GRP
- Filing Date
- 2025-08-06
- Publication Date
- 2026-07-21
AI Technical Summary
Traditional pulverized coal screens, when operating at high speeds, cause excessive retention of qualified pulverized coal, leading to increased equipment load, higher energy consumption, and reduced output, making it difficult to effectively control pulverized coal particle size.
A pulverized coal screen with controllable mesh size is used. A variable frequency motor drives the impeller to form a strong centrifugal force field. Combined with laser particle size analyzer detection and closed-loop control system, the impeller speed is dynamically adjusted to ensure that the proportion of 200-mesh pulverized coal is below 80%.
It enables precise control of coal powder particle size, reduces equipment load and energy consumption, and improves pulverization output and product quality.
Smart Images
Figure CN224524957U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of pulverized coal sieve technology, specifically a pulverized coal sieve with controllable mesh size. Background Technology
[0002] The pulverized coal screen is a key piece of equipment in the pulverized coal injection system of the blast furnace in the iron and steel industry, used for pulverized coal preparation and screening. Its main function is to classify the particle size of the ground pulverized coal and separate fine pulverized coal that meets the injection requirements (usually requiring a particle size ≤200 mesh).
[0003] After pulverized coal enters the separator with the airflow, centrifugal force is generated during the rotational motion. The coarser and larger the particles, the stronger the centrifugal force, and the easier it is to be thrown against the separator wall. The coarse particles thrown against the separator wall fall down along the wall and enter the return powder chamber. Fine particles, due to their small mass and weak centrifugal force, are carried upward by the central airflow and discharged from the outlet. In traditional processes, in order to pursue a high proportion of fine powder (such as 200 mesh > 80%), the separator speed needs to be increased to enhance the screening of fine powder. However, high speed will cause qualified pulverized coal (coarse powder) to be excessively retained, and a large number of particles will circulate and grind in the system, resulting in increased equipment load, increased energy consumption, and decreased actual output. Therefore, a pulverized coal injection screen with controllable mesh size is needed. Utility Model Content
[0004] The purpose of this invention is to provide a pulverized coal injection screen with controllable mesh size to solve the problems mentioned in the background art.
[0005] To achieve the above objectives, this utility model provides the following technical solution: a controllable mesh size pulverized coal sieve, comprising a pulverizing sieve body, an impeller, a discharge port, and a coal inlet. A coal inlet is located at the top of one side of the pulverizing sieve body, and one end of the coal inlet is connected to a coal inlet pipe. A fan is located at the input end of the coal inlet pipe. An impeller is located at the center of the pulverizing sieve body via a rotating shaft. A drive box is located at the top of the pulverizing sieve body, and a variable frequency motor is located inside the drive box. A drive gear is located at the output end of the variable frequency motor via a roller. A powder return chamber is located at the bottom of the pulverizing sieve body, and a discharge port is located at one end of the top of the pulverizing sieve body. A sampling pipe is located on one side of the discharge port, and a negative pressure pump is installed on the sampling pipe.
[0006] Preferably, the top end of the rotating shaft extends into the drive housing, and the top end of the rotating shaft is provided with a driven gear that meshes with the driving gear.
[0007] Preferably, baffles are evenly provided on both sides of the inside of the coal inlet through damping shafts, and one side of each baffle is connected to the inner wall of the coal inlet by a spring.
[0008] Preferably, the upper surface of the impeller is provided with an upper wear-resistant layer, and the lower surface of the impeller is provided with a lower wear-resistant layer.
[0009] Preferably, the upper wear-resistant layer is made by tungsten carbide spraying, and the lower wear-resistant layer is made by overlay welding of high-chromium alloy.
[0010] Preferably, a support bracket is provided on one side of the pulverizing screen body via a support frame, and the top of the support bracket is connected to the bottom of the coal inlet pipe.
[0011] Preferably, the cross-section of the support bracket is arc-shaped, and the top surface of the support bracket is uniformly provided with reserved grooves, and each reserved groove is embedded with an elastic protrusion.
[0012] Compared with the prior art, the beneficial effects of this utility model are as follows: This controllable mesh coal pulverizing screen is equipped with a pulverizing screen body, a coal inlet, a return powder chamber, an impeller, a drive box, a variable frequency motor, a drive gear, a driven gear, a rotating shaft, a discharge port, a sampling pipe, and a negative pressure pump. The coal powder to be separated enters from the coal inlet and flows downward to the impeller area. The variable frequency motor drives the drive gear to rotate, causing the driven gear and the rotating shaft to rotate. The impeller drives the surrounding airflow to form a strong centrifugal force field. Coarse coal powder particles, due to their larger mass, have a centrifugal force greater than the airflow drag force and are thrown towards the inner wall of the pulverizing screen body, sliding down the wall to the bottom return powder chamber. Fine particles, due to their smaller mass and weaker centrifugal force, are carried upward by the central airflow and discharged from the coal outlet. Fine coal powder is extracted through the sampling pipe to a laser particle size analyzer for detection. The speed of the variable frequency motor is adjusted according to the mesh number feedback. If there are too many coarse particles, the impeller speed is increased; conversely, the impeller speed is decreased, controlling the 200-mesh coal powder particle size to be below 80%, thereby achieving the goal of increasing the pulverizing output. Attached Figure Description
[0013] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.
[0014] Figure 1 This is a frontal cross-sectional view of the present invention.
[0015] Figure 2 For the present utility model Figure 1 Enlarged structural diagram at point A in the middle;
[0016] Figure 3 This is a schematic diagram of the impeller structure of this utility model;
[0017] Figure 4 For the present utility model Figure 1 Enlarged structural diagram at point B;
[0018] Figure 5 This is a schematic diagram of the support structure of this utility model.
[0019] In the diagram: 1. Main body of the powder sieve; 2. Impeller; 3. Sampling tube; 4. Negative pressure pump; 5. Rotating shaft; 6. Discharge port; 7. Powder return chamber; 8. Fan; 9. Coal inlet pipe; 10. Support bracket; 11. Drive box; 12. Variable frequency motor; 13. Drive gear; 14. Driven gear; 15. Upper wear-resistant layer; 16. Lower wear-resistant layer; 17. Coal inlet; 18. Baffle; 19. Spring; 20. Reserved groove; 21. Elastic protrusion. Detailed Implementation
[0020] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model without creative effort are within the scope of protection of the present utility model.
[0021] Please see Figure 1-5 An embodiment of this utility model is provided: a controllable mesh size pulverized coal injection screen, including a pulverized screen body 1, an impeller 2, a discharge port 6 and a coal inlet 17. The top of one side of the pulverized screen body 1 is provided with a coal inlet 17, and one end of the coal inlet 17 is connected to a coal inlet pipe 9. A fan 8 is provided at the input end of the coal inlet pipe 9.
[0022] Baffles 18 are evenly provided on both sides of the inside of the coal inlet 17 via damping shafts, and one side of each baffle 18 is connected to the inner wall of the coal inlet 17 via a spring 19.
[0023] When the blower 8 starts, it generates a positive pressure airflow that transports the coal powder through the coal inlet pipe 9 to the coal inlet 17. When the coal powder enters the coal inlet 17, the baffle 18 opens under the impact of the airflow to overcome the resistance of the spring 19 and slow down the feeding speed.
[0024] A support bracket 10 is provided on one side of the main body 1 of the powder screen via a bracket, and the top of the support bracket 10 is connected to the bottom of the coal inlet pipe 9, so that the weight of the coal inlet pipe 9 is evenly distributed on the support bracket 10, avoiding local stress concentration that could lead to pipe deformation or breakage.
[0025] The cross-section of the support 10 is arc-shaped, and the top surface of the support 10 is evenly provided with reserved grooves 20. Each reserved groove 20 is embedded with an elastic protrusion 21, which is made of rubber.
[0026] When the coal inlet pipe 9 vibrates due to airflow impact or impeller 2 operation, the elastic protrusion 21 absorbs vibration energy through compression deformation, reduces pipe swaying, and avoids problems such as bolt loosening and pipe joint leakage caused by rigid connection.
[0027] An impeller 2 is installed in the center of the powder sieve body 1 via a rotating shaft 5, and a drive box 11 is installed at the top of the powder sieve body 1. A variable frequency motor 12 is installed inside the drive box 11, and a drive gear 13 is installed at the output end of the variable frequency motor 12 via a roller.
[0028] The variable frequency motor 12 drives the drive gear 13 to rotate, which in turn drives the driven gear 14 and the impeller 2 of the rotating shaft 5 to rotate at high speed through gear meshing, forming a strong centrifugal force field.
[0029] The upper surface of the impeller 2 is provided with an upper wear-resistant layer 15, and the lower surface of the impeller 2 is provided with a lower wear-resistant layer 16.
[0030] The upper wear-resistant layer 15 is made of tungsten carbide spraying process, which effectively resists the high-speed impact wear of coarse coal powder particles and reduces the generation of surface pits or cracks. The lower wear-resistant layer 16 is made of high chromium alloy by overlay welding, which can withstand the long-term sliding friction of coal powder particles and resist wear caused by particle cutting.
[0031] The bottom end of the powder sieve body 1 is provided with a powder return chamber 7, and the top end of the powder sieve body 1 is provided with a discharge port 6.
[0032] Coarse coal powder particles are thrown towards the inner wall of the pulverizing screen body 1 due to the centrifugal force being greater than the airflow drag force, and slide down the inner wall to the bottom return chamber 7, and return to the coal mill for further processing through the pipeline. Fine coal powder particles are carried towards the discharge port 6 by the central rising airflow due to the weak centrifugal force.
[0033] A sampling tube 3 is provided on one side of the discharge port 6, and a negative pressure pump 4 is provided on the sampling tube 3. The negative pressure pump 4 extracts fine coal powder samples from the discharge port 6 through the sampling tube 3. The samples are transported to the laser particle size analyzer (unmarked). The external equipment detects the real-time particle size distribution, and the detection data is converted into mesh count and fed back to the control system. The control system compares the measured mesh count with the set value and calculates the deviation.
[0034] If the measured mesh size is lower than the set value and there are too many coarse particles, the control system outputs a signal to increase the speed of the variable frequency motor 12, and the centrifugal force of the impeller 2 is enhanced. More coarse particles are separated into the return powder chamber 7 and then re-grinded. If the measured mesh size is higher than the set value and there are too many fine particles, the control system reduces the speed of the variable frequency motor 12, and the centrifugal force of the impeller 2 is weakened. Some medium-sized coal powder particles that are close to the target mesh size will be directly discharged with the airflow due to insufficient centrifugal force and will no longer enter the return powder chamber 7 for recycling and grinding, thereby increasing the powder production.
[0035] By using a closed-loop control system of detection, feedback, and adjustment, combined with the dynamic adjustment of the impeller speed, the system can effectively control the particle size of the pulverized coal output.
[0036] The specific models and specifications of the variable frequency motor 12, negative pressure pump 4, and fan 8 need to be determined by selection calculation based on the specifications and parameters of the device. The selection calculation method is existing technology, so it will not be described in detail here.
[0037] Working Principle: In this embodiment, when in use, the blower 8 starts, generating a positive pressure airflow that transports pulverized coal through the coal inlet pipe 9 to the coal inlet 17. When the pulverized coal enters the coal inlet 17, the baffle 18 opens under the impact of the airflow, overcoming the resistance of the spring 19. The pulverized coal enters through the gap of the baffle 18, slowing down the feeding speed. The pulverized coal flows downward along the coal inlet 17 to the impeller 2 area inside the pulverizing screen body 1. The variable frequency motor 12 drives the drive gear 13 to rotate, which in turn drives the driven gear 14 and the impeller 2 of the rotating shaft 5 to rotate at high speed through gear meshing, forming a strong centrifugal force field. Coarse pulverized coal particles are thrown towards the inner wall of the pulverizing screen body 1 because the centrifugal force is greater than the airflow drag force, and slide down the inner wall to the bottom return chamber 7. They are then returned to the coal mill for reprocessing through the pipeline. Fine pulverized coal particles are carried towards the discharge port 6 by the central rising airflow because the centrifugal force is weak. The negative pressure pump 4 draws the pulverized coal from the discharge port 6 through the sampling pipe 3. Fine coal powder samples are extracted and transported to an unlabeled laser particle size analyzer. The external equipment detects the real-time particle size distribution, and the detection data is converted into mesh count and fed back to the control system. The control system compares the measured mesh count with the set value and calculates the deviation. If the measured mesh count is lower than the set value and there are too many coarse particles, the control system outputs a signal to increase the speed of the variable frequency motor 12, which enhances the centrifugal force of the impeller 2. More coarse particles are separated into the return powder chamber 7 and then re-grinded. If the measured mesh count is higher than the set value and there are too many fine particles, the control system reduces the speed of the variable frequency motor 12, which weakens the centrifugal force of the impeller 2. Some medium-sized coal powder particles that are close to the target mesh count will be directly discharged with the airflow due to insufficient centrifugal force and will not enter the return powder chamber 7 for recycling and grinding, thereby increasing the coal powder output. Through the "detection, feedback, and adjustment" closed-loop control link, combined with the dynamic adjustment of the impeller 2 speed, the system can effectively control the mesh count of the coal powder output.
[0038] The above are merely preferred embodiments of this utility model and are not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A controllable mesh size pulverized coal screen, characterized in that, The pulverizing screen includes a main body (1), an impeller (2), a discharge port (6), and a coal inlet (17). A coal inlet (17) is located at the top of one side of the main body (1), and one end of the coal inlet (17) is connected to a coal inlet pipe (9). A fan (8) is located at the input end of the coal inlet pipe (9). An impeller (2) is located at the center of the main body (1) via a rotating shaft (5), and a fan (8) is located at the top of the main body (1). The drive box (11) is equipped with a variable frequency motor (12) inside the drive box (11), and the output end of the variable frequency motor (12) is equipped with a drive gear (13) through a roller. The bottom end of the powder sieve body (1) is equipped with a powder return chamber (7), and one end of the top of the powder sieve body (1) is equipped with a discharge port (6). A sampling tube (3) is provided on one side of the discharge port (6), and a negative pressure pump (4) is provided on the sampling tube (3).
2. The controllable mesh size pulverizing screen for pulverized coal injection according to claim 1, characterized in that: The top end of the rotating shaft (5) extends into the drive box (11), and the top end of the rotating shaft (5) is provided with a driven gear (14) that meshes with the driving gear (13).
3. The controllable mesh size pulverizing screen for pulverized coal injection according to claim 1, characterized in that: The inside of the coal inlet (17) is provided with baffles (18) evenly arranged on both sides through damping shafts, and one side of each baffle (18) is connected to the inner wall of the coal inlet (17) through a spring (19).
4. The controllable mesh size pulverizing screen for pulverized coal injection according to claim 1, characterized in that: The upper surface of the impeller (2) is provided with an upper wear-resistant layer (15), and the lower surface of the impeller (2) is provided with a lower wear-resistant layer (16).
5. A controllable mesh size pulverizing screen for pulverized coal injection according to claim 4, characterized in that: The upper wear-resistant layer (15) is made by tungsten carbide spraying process, and the lower wear-resistant layer (16) is made by high chromium alloy overlay welding.
6. The controllable mesh size pulverizing screen for pulverized coal according to claim 1, characterized in that: The main body (1) of the powder screen has a support bracket (10) on one side, and the top of the support bracket (10) is connected to the bottom of the coal inlet pipe (9).
7. A controllable mesh size pulverizing screen for pulverized coal injection according to claim 6, characterized in that: The cross-section of the support bracket (10) is arc-shaped, and the top surface of the support bracket (10) is uniformly provided with reserved grooves (20), and each reserved groove (20) has an elastic protrusion (21) embedded inside.