Micron particle grading device and method for coal mill

Abstract

The invention relates to the technical field of coal processing, and discloses a micron particle grading device for a coal mill and a method thereof.The micron particle grading device comprises a grading mechanism, and the grading mechanism is installed above the coal mill; the grading mechanism comprises a grading shell, a grading top shell is mounted at the top of the grading shell, a powder outlet pipe is mounted at the top of the grading top shell, a mounting opening is formed in the top of the grading top shell, an upper cover is mounted in the mounting opening, a variable frequency motor is mounted at the top of the grading top shell, and a rotor is mounted in the upper cover. According to the micron particle grading device for the coal mill and the method of the micron particle grading device, the micron particle grading device is composed of a grading outer shell, a grading top shell, a powder outlet pipe, an upper cover, a variable frequency motor, a rotating blade set, a material returning hopper and the like; the device has the characteristics of uniform separation, high separation efficiency, improved pulverized coal fineness and improved pulverized coal combustion efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of coal processing and application, and in particular to a micron particle classification device and method for a coal mill. Background Art

[0002] Coal is known as black gold and food for industry. It has been one of the main energy sources used by the human world since the 18th century. Since the 21st century, although the value of coal is not as high as before, it has been one of the indispensable sources of energy for our production and life for a long time. The supply of coal is also related to the stability of the development of our country's industry and even the entire society. The security of coal supply is also the most important link in our country's energy security.

[0003] The coal mill is the most important auxiliary machine in the boiler pulverizing system. It is responsible for grinding the raw coal into coal powder of qualified fineness and blowing it into the boiler for combustion. The coal mill pulverizer selection device, as the pulverizing system's pulverizing device, determines the fineness and uniformity of the coal powder delivered by the coal mill, and directly affects the combustion effect, fly ash and coarse slag of the boiler.

[0004] In the coal processing industry, the fineness and uniformity of coal powder have an important impact on subsequent combustion efficiency, pollutant emissions, etc. In the grinding process of traditional coal mills, it is often difficult to directly obtain uniform particle size distribution. Therefore, there is an urgent need for a device and method that can efficiently and accurately classify coal powder into micron-level particles, which is of great significance for improving coal processing efficiency and optimizing coal powder quality. Summary of the invention

[0005] The object of the present invention is to provide a micron particle classification device and method for a coal mill to solve the problems raised in the above background technology.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions: a micron particle classification device for a coal mill, comprising a classification mechanism, wherein the classification mechanism is installed above the coal mill; The grading mechanism comprises a grading shell, a grading top shell is installed on the top of the grading shell, a powder outlet pipe is installed on the top of the grading top shell, a mounting opening is opened on the top of the grading top shell, an upper cover is installed in the mounting opening, a variable frequency motor is installed on the top of the grading top shell, a rotor is installed inside the upper cover, a rotating blade group is installed on the outside of the rotor, a belt is installed on the outside of the rotor, a coupling is installed on the top of the grading top shell, a pulley is installed on the top of the coupling, a stationary blade group is installed inside the grading shell, and a return hopper is installed inside the grading shell.

[0007] Preferably, a transmission housing is installed on the top of the upper cover, and the belt is located in the transmission housing.

[0008] Preferably, the pulley is located in a transmission housing, and an end of the belt away from the rotor is mounted on the outside of the pulley.

[0009] Preferably, the output end of the variable frequency motor is connected to a coupling, and a plurality of the powder outlet pipes are provided, and the plurality of the powder outlet pipes are arranged in a ring array.

[0010] A method for micron particle classification of a coal mill comprises the following steps: Data collection: Collect basic information about the coal mill, including the quality parameters of the coal used, coal powder parameters, basic parameters of the coal mill, operating parameters of the coal mill, internal wear of the coal mill, data on the existing separator interface of the coal mill, and the working space around the coal mill; Technical design: Preliminary design of the micron particle classification device based on the data collected in the on-site data collection step, including equipment volume space, dynamic and static blade size and blade shape, rated speed of the rotor, and the location and size of the guide; Flow field simulation: Use fluid software to simulate the flow field, calculate the resistance, pressure field distribution, and velocity field distribution of the separator, and after repeated simulation verification, determine the most reasonable and efficient classification device that best matches the on-site working conditions; Determine the solution: Determine the technical parameters and size parameters of the corresponding micron particle classification device according to the smooth simulation steps, establish a three-dimensional model and conduct the final simulation analysis.

[0011] Preferably, in the data collection step, the quality parameters of the coal include the ash content, volatile matter, moisture content and fixed carbon of the coal, the coal powder parameters include the coal powder particle size distribution, humidity and uniformity, the basic parameters of the coal mill include the model and specifications, power, production capacity and structural layout of the coal mill, the operating condition parameters of the coal mill include feed rate, outlet temperature, air volume and vibration, the internal wear of the coal mill includes grinding disc wear, grinding roller wear, liner wear and wear of other parts, the existing separator interface data of the coal mill includes the size, position and type of the interface, and the working space around the coal mill includes the space size, ambient temperature and ventilation conditions around the coal mill.

[0012] Preferably, in the technical design step, a preliminary design of the micron particle classification device is performed based on the data collected in the data collection step, wherein the design of the equipment volume space includes the total volume of the classification shell and the layout of the internal space, the design of the moving and stationary blade size and blade shape includes the size and shape of the rotating blade group and the stationary blade group, the setting of the rated speed of the rotor includes the speed range and speed adjustment of the variable frequency motor, and the position and size of the guide in the coal mill.

[0013] Preferably, in the flow field simulation step, computational fluid dynamics (CFD) software is used to simulate the flow field resistance, inlet pressure field and outlet pressure field distribution, inlet and outlet velocity field and internal velocity field distribution in the separator, and multiple rounds of simulations are used to verify the effects of different design schemes to ensure the best design scheme.

[0014] Preferably, in the scheme determination step, the separation efficiency index, energy consumption and long-term operation reliability of the separator are determined first, and then the total size of the grading shell, the size and shape of the rotating blade group and the stationary blade group, the speed range and speed adjustment of the variable frequency motor, etc. are determined, and finally a three-dimensional model is established, and a final simulation analysis is performed on the three-dimensional model.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are: First, the present invention, the micron particle classification device is composed of a classification shell, a classification top shell, a powder discharge pipe, an upper cover, a frequency conversion motor, a rotating blade group, a return hopper and other parts, and through the micron particle classification method of the coal mill, the device has the characteristics of uniform separation, high separation efficiency, improved coal powder fineness, and improved coal powder combustion efficiency.

[0016] Second, the present invention adopts a frequency converter to control and adjust the frequency conversion motor, which can be directly controlled by a DCS system or operated on-site by a single machine. The speed of the rotating blade group of the classifying device can be adjusted in real time according to the actual coal powder fineness requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a front cross-sectional structural schematic diagram of the micron particle classification device of the present invention; Figure 2 It is a schematic diagram of the top view of the micron particle classification device of the present invention; Figure 3 This is a schematic diagram of the process structure of the method for classifying micron particles of the present invention; Figure 4 This is a schematic diagram of the data collection process structure of the present invention; Figure 5 A schematic diagram of the structure of the technical design process of the present invention; Figure 6 It is a schematic diagram of the flow field simulation process structure of the present invention; Figure 7 The present invention determines the scheme flow structure schematic diagram.

[0018] Among them: 1. Classification shell; 2. Classification top shell; 3. Powder outlet pipe; 4. Upper cover; 5. Frequency conversion motor; 6. Rotating blade group; 7. Stationary blade group; 8. Return hopper; 9. Transmission shell. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The present invention provides the following technical solutions: Embodiment 1 See also Figure 1-2 , a micron particle classification device for a coal mill, comprising a classification mechanism, the classification mechanism being installed above the coal mill; The grading mechanism comprises a grading shell 1, a grading top shell 2 is installed on the top of the grading shell 1, a powder outlet pipe 3 is installed on the top of the grading top shell 2, a mounting opening is opened on the top of the grading top shell 2, an upper cover 4 is installed in the mounting opening, a frequency conversion motor 5 is installed on the top of the grading top shell 2, a rotor is installed inside the upper cover 4, a rotating blade group 6 is installed on the outside of the rotor, a belt is installed on the outside of the rotor, a coupling is installed on the top of the grading top shell 2, a pulley is installed on the top of the coupling, a stationary blade group 7 is installed inside the grading shell 1, and a return hopper 8 is installed inside the grading shell 1.

[0021] A transmission housing 9 is installed on the top of the upper cover 4 , and the belt is located in the transmission housing 9 .

[0022] The pulley is located in the transmission housing 9, and the end of the belt away from the rotor is installed on the outside of the pulley.

[0023] The output end of the variable frequency motor 5 is connected to the coupling. A plurality of powder outlet pipes 3 are provided, and the plurality of powder outlet pipes 3 are arranged in a ring array.

[0024] Through the above technical scheme, after the raw coal is crushed and ground by the coal mill, the coal powder is fully mixed and dried by the spiral rising primary air and then transported to the micron particle classification device. The rotor is driven to rotate by the frequency conversion motor 5 and the belt. The frequency conversion motor 5 is controlled and adjusted by the frequency converter. It can be directly controlled by the DCS system or operated on a single machine. The speed of the rotating blade group 6 of the classification device can be adjusted in real time according to the actual coal powder fineness requirements, so that the wind and powder mixture of different particle sizes can obtain uniform tangential flow after passing through the evenly distributed rotating blade group 6 and the stationary blade group 7. The annular area between the rotating blade group 6, the stationary blade group 7 and the rotor can be called the powder selection area. The coal powder particles of different particle sizes entering this area are affected by the rotor. The rotation generates centrifugal forces of different sizes and the centripetal force exerted by the traction of the primary air flow. At the same time, the coal powder is subjected to the centrifugal forces of different sizes generated by the rotation of the rotor and the centripetal force exerted by the traction of the primary air flow. When the rotor speed and the primary air flow are constant, the coal powder below the cutting particle size in the powder selection area is in a static state because the centrifugal force and the centripetal force are equal. The coarse particles exceeding the cutting particle size fly out under the action of centrifugal force and move outward, hit the static blade group 7 and settle under the action of gravity, and return to the grinding disc in the coal mill through the powder return hopper 8 for re-grinding. The qualified fine powder smaller than the cutting particle size cannot overcome the traction of the air flow, passes through the rotor blades, leaves the micron particle classification device, and enters the boiler for combustion through the powder discharge pipe 3.

[0025] Embodiment 2 See also Figure 3-7 , a method for micron particle classification of a coal mill, comprising the following steps: 1. Data collection: Collect basic information about the coal mill, including the quality parameters of the coal used, coal powder parameters, basic parameters of the coal mill, operating parameters of the coal mill, internal wear of the coal mill, data on the existing separator interface of the coal mill, and the working space around the coal mill.

[0026] According to the on-site conditions, the quality parameters of the coal used include the ash content, volatile matter, moisture content and fixed carbon of the coal, the coal powder parameters include the coal powder particle size distribution, humidity and uniformity, the basic parameters of the coal mill include the model and specifications, power, production capacity and structural layout of the coal mill, the operating condition parameters of the coal mill include feed rate, outlet temperature, air volume and vibration, the internal wear of the coal mill includes the wear of the grinding disc, grinding roller, liner and other parts, the existing separator interface data of the coal mill includes the size, position and type of the interface, the working space around the coal mill includes the space size, ambient temperature and ventilation conditions around the coal mill, so as to provide data support for subsequent design.

[0027] 2. Technical design: Based on the data collected in the on-site data collection step, a preliminary design of the micron particle classification device is made, including the equipment volume space, the size and shape of the moving and stationary blades, the rated speed of the rotor, and the location and size of the guide.

[0028] The total volume and internal space layout of the grading shell 1 are preliminarily designed based on the data collected in the on-site data collection step to ensure that the requirements of coal powder flow are met and dead corners and turbulence are avoided to ensure smooth airflow. The design of the size and shape of the moving and stationary blades includes the size and shape of the rotating blade group 6 and the stationary blade group 7 to ensure the stability and strength of the rotating blade group 6 during high-speed rotation and the stationary blade group 7 can effectively guide the airflow in a fixed state. The setting of the rated speed of the rotor includes the speed range and speed adjustment of the variable frequency motor 5. The optimal speed range of the variable frequency motor 5 is determined according to the coal powder characteristics and separation requirements. The position and size of the guide in the coal mill ensure that the airflow enters the grading device smoothly and the airflow is not obstructed when entering the grading device.

[0029] 3. Flow field simulation: Use fluid software to simulate the flow field, calculate the resistance, pressure field distribution, and velocity field distribution of the separator, and after repeated simulation and verification, determine the most reasonable and efficient classification device that best matches the on-site working conditions.

[0030] The resistance of the separator is simulated by CFD software to ensure that the resistance is minimized, the pressure distribution at the inlet is simulated to ensure smooth entry of the airflow, the pressure distribution at the outlet is simulated to ensure smooth discharge of the airflow, the velocity distribution at the inlet and outlet is simulated to ensure smooth airflow, and the velocity distribution changes in the entire grading device are simulated to ensure uniform airflow. The effects of different design schemes are verified through multiple rounds of simulation to ensure the best design scheme, and parameters are continuously adjusted to find the best design scheme to ensure efficient operation.

[0031] 4. Determine the solution: Determine the technical parameters and size parameters of the corresponding micron particle classification device according to the smooth simulation steps, establish a three-dimensional model and conduct the final simulation analysis.

[0032] Determine the separation efficiency index of the separator to ensure that the expected separation effect is achieved, determine the energy consumption level of the separator to ensure economy and energy saving, ensure long-term reliability, and reduce the failure rate. Finally, determine the overall size of the classification housing 1 to ensure compatibility with existing equipment, determine the specific size and shape of the rotating blade group 6 and the stationary blade group 7 to ensure that each component can perform at its best, determine the speed range and speed adjustment of the variable frequency motor 5 to ensure flexibility and adaptability, use professional software (such as SolidWorks, AutoCAD, etc.) to establish a three-dimensional model of the classification device to ensure that the design details are accurate, and conduct a final simulation analysis on the three-dimensional model to ensure the feasibility and effectiveness of the design.

[0033] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and alterations may be made to the embodiments without departing from the principles and spirit thereof, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A micron particle classification device for a coal mill, comprising a classification mechanism, characterized in that: The grading mechanism is installed above the coal mill; The grading mechanism comprises a grading shell (1), a grading top shell (2) is installed on the top of the grading shell (1), a powder outlet pipe (3) is installed on the top of the grading top shell (2), a mounting opening is opened on the top of the grading top shell (2), an upper cover (4) is installed in the mounting opening, a variable frequency motor (5) is installed on the top of the grading top shell (2), a rotor is installed inside the upper cover (4), a rotating blade group (6) is installed on the outside of the rotor, a belt is installed on the outside of the rotor, a coupling is installed on the top of the grading top shell (2), a pulley is installed on the top of the coupling, a stationary blade group (7) is installed inside the grading shell (1), and a return hopper (8) is installed inside the grading shell (1).

2. The micron particle classification device for coal mill according to claim 1, characterized in that: A transmission housing (9) is installed on the top of the upper cover (4), and the belt is located inside the transmission housing (9).

3. The micron particle classification device for coal mill according to claim 1, characterized in that: The pulley is located in the transmission housing (9), and one end of the belt away from the rotor is mounted on the outside of the pulley.

4. The micron particle classification device for coal mill according to claim 1, characterized in that: The output end of the variable frequency motor (5) is connected to a coupling, and a plurality of the powder outlet pipes (3) are provided, and the plurality of the powder outlet pipes (3) are arranged in a ring array.

5. The method for micron particle classification of a coal mill according to claim 1, characterized in that: The following steps are involved: Data collection: Collect basic information about the coal mill, including the quality parameters of the coal used, coal powder parameters, basic parameters of the coal mill, operating parameters of the coal mill, internal wear of the coal mill, data on the existing separator interface of the coal mill, and the working space around the coal mill; Technical design: Preliminary design of the micron particle classification device based on the data collected in the on-site data collection step, including equipment volume space, dynamic and static blade size and blade shape, rated speed of the rotor, and the location and size of the guide; Flow field simulation: Use fluid software to simulate the flow field, calculate the resistance, pressure field distribution, and velocity field distribution of the separator, and after repeated simulation verification, determine the most reasonable and efficient classification device that best matches the on-site working conditions; Determine the solution: Determine the technical parameters and size parameters of the corresponding micron particle classification device according to the smooth simulation steps, establish a three-dimensional model and conduct the final simulation analysis.

6. A method for classifying micron particles in a coal mill according to claim 1, characterized in that: In the data collection step, the quality parameters of the coal include the ash content, volatile matter, moisture content and fixed carbon of the coal, the coal powder parameters include the coal powder particle size distribution, humidity and uniformity, the basic parameters of the coal mill include the model and specifications, power, production capacity and structural layout of the coal mill, the operating condition parameters of the coal mill include feed rate, outlet temperature, air volume and vibration, the internal wear of the coal mill includes the wear of the grinding disc, grinding roller, liner and other parts, the existing separator interface data of the coal mill includes the size, location and type of the interface, and the working space around the coal mill includes the space size, ambient temperature and ventilation conditions around the coal mill.

7. The method for micron particle classification of a coal mill according to claim 1, characterized in that: In the technical design step, a preliminary design of the micron particle classification device is carried out based on the data collected in the data collection step, wherein the design of the equipment volume space includes the total volume of the classification shell (1) and the layout of the internal space, the design of the size and shape of the moving and stationary blades includes the size and shape of the rotating blade group (6) and the stationary blade group (7), the setting of the rated speed of the rotor includes the speed range and speed adjustment of the variable frequency motor (5), and the position and size of the guide in the coal mill.

8. The method for micron particle classification of a coal mill according to claim 1, characterized in that: In the flow field simulation step, computational fluid dynamics (CFD) software is used to simulate the flow field resistance, inlet pressure field and outlet pressure field distribution, inlet and outlet velocity field and internal velocity field distribution in the separator. Multiple rounds of simulations are used to verify the effects of different design schemes to ensure the best design scheme.

9. The micron particle classification device and method for coal mill according to claim 1, characterized in that: In the scheme determination step, the separation efficiency index, energy consumption and long-term operation reliability of the separator are first determined, and then the overall size of the classification housing (1), the size and shape of the rotating blade group (6) and the stationary blade group (7), the speed range and speed adjustment of the variable frequency motor (5), etc. are determined. Finally, a three-dimensional model is established and a final simulation analysis is performed on the three-dimensional model.

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