Device for improving airflow in medium-speed coal mill and improving output

Abstract

The utility model discloses a device for improving airflow in a medium-speed coal mill and improving output, which is characterized in that an air source pipe is additionally arranged behind each milling roller in the existing medium-speed coal mill, and an airflow stagnation or irregular movement area is arranged at the edge of each air source pipe towards a millstone and a milling roller shell. The pulverized coal in the area can reach the position above the air ring, the qualified pulverized coal is blown to the air and pulverized coal outlet through the air ring, and the unqualified pulverized coal enters the grinding disc to be ground again. The structure can increase disturbance to a coal seam on the outer side area of the grinding roller, improve the situation of airflow stagnation or irregular movement in the partial area of the edge of the coal mill shell, and reduce the thickness of the coal seam to increase the output of the coal mill.

Description

Technical Field

[0001] This utility model belongs to the field of coal mill technology, specifically relating to a device for improving the airflow inside a medium-speed coal mill to increase output. Background Technology

[0002] With the transformation of the global energy structure and the rapid development of new energy technologies, the electricity market is undergoing unprecedented changes. New energy sources such as solar and wind power are increasingly accounting for a larger share of the electricity supply due to their clean and renewable characteristics. However, these new energy sources are intermittent and unstable, placing higher demands on the grid's peak-shaving and rapid load response capabilities. Against this backdrop, coal-fired power plants, traditionally the mainstay of electricity supply, are gradually shifting their role from basic power supply to serving as a "ballast" for grid peak-shaving and rapid load response.

[0003] To cope with the changes in the electricity market brought about by the addition of new energy sources and to enhance their survival capabilities in a highly competitive market, thermal power plants have adopted various strategies to optimize power generation costs. Among these, blending different coal sources has become a common cost control method. However, while this strategy brings cost reductions, it also introduces new problems. Low-cost coal sources often come with higher ash and moisture content, and these unfavorable factors pose a serious challenge to medium-speed coal mill pulverizing systems.

[0004] Coal mills are generally classified into low-speed, medium-speed, and high-speed coal mills based on their rotational speed. Low-speed coal mills typically operate at 15–25 rpm; medium-speed coal mills operate at 50–300 rpm; and high-speed coal mills typically operate at 500–1500 rpm.

[0005] As a core piece of equipment in the pulverizing system of coal-fired power plants, the performance of medium-speed coal mills directly affects the power generation efficiency and operational stability of the unit. However, the impurity and deterioration of coal quality, especially the increase in ash and moisture, easily leads to a greater weight of pulverized coal. The air rings arranged around the mill disc are designed to blow out all the compliant pulverized coal, resulting in a series of problems for medium-speed coal mills, such as limited output, accelerated wear, and increased energy consumption. Furthermore, there are areas of stagnant or irregular airflow at the edges of the mill disc and roller shells, affecting the carrying effect of hot air on pulverized coal. This causes some pulverized coal to easily accumulate in these areas, especially with the deterioration of coal quality, as the increased mass of the pulverized coal further exacerbates the accumulation of pulverized coal in these areas. Utility Model Content

[0006] The purpose of this utility model is to overcome the shortcomings of the prior art and provide a device to improve the airflow inside a medium-speed coal mill and increase its output, so as to solve the problem that the output of the coal mill is affected by the mixing and deterioration of coal quality in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A device for improving airflow inside a medium-speed coal mill to increase output includes an air source pipe disposed on the outside of each grinding roller, and a nozzle assembly disposed at the outlet of the air source pipe; the lower end of the grinding roller contacts the grinding disc, and an air ring is disposed circumferentially around the outside of the grinding disc;

[0009] The nozzle assembly is directed towards the contact point between the grinding roller and the grinding disc, and the nozzle assembly is equipped with several nozzles.

[0010] The further improvement of this utility model is as follows:

[0011] Preferably, each air supply pipe is equipped with an air supply pipe regulating damper.

[0012] Preferably, each of the gas source pipes is fixedly installed in the medium-speed coal mill via a nozzle fixing bracket.

[0013] Preferably, all gas source pipes are connected to the main gas source pipe.

[0014] Preferably, the main gas pipe is a primary air duct, and the primary air duct is connected to the air ring.

[0015] Preferably, the gas source pipe is an inverted U-shaped pipe.

[0016] Preferably, a horizontal nozzle pipe is provided at the outlet of the gas source pipe, the nozzle pipe is arranged in a horizontal direction, and the nozzle group is arranged along the length direction of the nozzle pipe.

[0017] Preferably, the nozzle group is provided with a plurality of nozzles distributed at equal intervals.

[0018] Preferably, a coal drop pipe is provided above the grinding disc; and a coal outlet is provided above the air ring and nozzle assembly.

[0019] Preferably, the grinding disc is mounted on a reducer, the reducer is connected to a motor, and the motor and reducer are mounted on the base of the coal mill.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] This utility model discloses a device for improving airflow and increasing output in a medium-speed coal mill. The device adds an air source pipe behind each grinding roller in the existing medium-speed coal mill. Each air source pipe faces an area where airflow stagnation or irregular movement exists at the edge of the grinding disc and roller shell. This allows coal dust in this area to reach above the air ring. Qualified coal dust is blown through the air ring to the air-coal outlet, while unqualified coal dust enters the grinding disc for re-grinding. This structure can increase disturbance in the coal bed outside the grinding roller area, improve the stagnant or irregular airflow in some areas of the coal mill shell edge, reduce the coal bed thickness, and thus increase the coal mill output.

[0022] Furthermore, hot air nozzles installed on the outside of the grinding roller are distributed at 120° intervals along the grinding disc area, with a total of 3 sets, covering the circumferential area inside the grinding roller and grinding disc air ring. The nozzles are at a certain angle to the grinding roller support, and the hot air ejected from the nozzle assembly forms an upward angle with the upward rotating air of the air ring. On the one hand, this strengthens the airflow disturbance in the grinding roller and grinding disc area, reduces the excessive grinding of coal powder and reduces the thickness of the coal layer in the grinding disc. On the other hand, it strengthens the movement of the ground coal powder particles towards the air ring opening at the periphery of the grinding disc, so that the dry hot air of the air ring can carry away the coal powder in time.

[0023] Furthermore, the hot air ejected from the nozzle assembly is drawn out from the primary air mixing duct and adjusted by the air source airflow regulating damper. This enhances the carrying capacity of the incoming airflow while maintaining a constant air-coal ratio in the coal mill, thereby increasing the mill's output capacity. The air source airflow regulating damper adjusts the airflow entering the nozzle assembly to ensure both minimal disturbance to the pulverized coal bed and a normal airflow velocity in the air ring. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of a device for improving airflow and increasing output in a medium-speed coal mill according to the present invention.

[0025] Figure 2 This is a top view of a device for improving airflow and increasing output in a medium-speed coal mill according to the present invention.

[0026] Figure 3 Side view of the grinding roller of this utility model Figure 1 ;

[0027] Figure 4 Side view of the grinding roller of this utility model Figure 2 ;

[0028] The components are: 1. Air source pipe; 2. Air source pipe regulating damper; 3. Nozzle assembly; 4. Nozzle fixing bracket; 5. Grinding roller; 6. Grinding disc; 7. Hot air inlet of air ring; 8. Motor; 9. Reducer; 10. Coal mill base; 11. Air ring; 12. Primary air duct; 13. Coal drop pipe; 14. Air-coal outlet. Detailed Implementation

[0029] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0030] Example 1

[0031] This utility model discloses a device for improving the airflow inside a medium-speed coal mill and increasing its output. The device adds several air source pipes 1 to the original medium-speed coal mill, and an air source pipe 1 is set on the outside of each grinding roller 5.

[0032] See Figure 1 The medium-speed coal mill includes a grinding disc 6 for carrying pulverized coal. An annular groove is provided on the edge of the grinding disc 6. Three grinding rollers 5 are arranged circumferentially above the annular groove. The grinding rollers 5 are evenly spaced along the circumference of the grinding disc 6, and the included angle between the axes of the three grinding rollers 5 is 120°. The lower part of the grinding rollers 5 contacts the grinding disc 6, and the grinding rollers 5 are connected to a power unit that provides power to them. As the grinding disc 6 and the grinding rollers 5 rotate, the pulverized coal is ground between the grinding disc 6 and the grinding rollers 5.

[0033] A ring of air 11 is arranged around the circumference of the grinding disc 6. A coal chute 13 is arranged above the grinding disc 6, and a ring of air-powder outlets 14 is arranged around the circumference of the coal chute 13, with the air-powder outlets 14 located above the air ring 11. The outlets of the air ring 11 face upwards, allowing the ground coal powder to move towards the air-powder outlets under the action of primary air. The air ring 11 provides hot air through the primary air duct 12.

[0034] The grinding disc is mounted on the reducer 9, which is connected to the motor 8. The reducer 9 and the motor 8 are fixedly mounted on the coal mill base 10.

[0035] The material falls into the center of the grinding disc 6 through the coal drop pipe 13. The motor 8 drives the grinding disc 6 to rotate through the reducer 9. The coal powder particles crushed and ground by the grinding disc 6 and the grinding rollers 5 move outward with the rotation of the grinding disc 6. As the grinding disc 6 rotates, the material moves towards the edge of the grinding disc 6 under the action of centrifugal force. When it passes through the annular groove on the grinding disc 6, it is crushed by the grinding rollers. The hot air used for drying the coal mill enters the grinding space of the coal mill through the air ring 11 around the grinding disc 6. The hot air carries the coal powder particles upward. The qualified coal powder leaves the coal mill and enters the coal powder pipeline system after separation. Large particles fall directly onto the grinding disc 6 for re-grinding. When the material in the airflow passes through the upper separator, under the action of the rotating rotor, the coarse powder falls from the cone hopper back to the grinding disc to be ground into powder again. By adjusting the separator, the required fineness of different products can be achieved. To increase the output of a medium-speed coal mill, it is necessary to increase the grinding capacity of the mill disc and rollers, and to ensure that the ground coal powder is carried away promptly to maintain a certain coal bed thickness on the mill disc and prevent mill blockage. Therefore, improving the internal flow field of the medium-speed coal mill to a certain extent can improve the mill's output.

[0036] The rotating grinding disc 6 and the edge of the grinding roller 5 housing have areas of stagnant or irregular airflow, which affects the carrying effect of hot air on pulverized coal.

[0037] In this invention, an air source pipe 1 is provided on the outer side of each grinding roller 5. It should be noted that the three grinding rollers 5 are all facing the center of the grinding disc 6 as the inner side, and the back of each grinding roller 5 is the outer side. An air source pipe 1 is provided on the outer side of each grinding roller 5, and a nozzle group 3 is provided at the outlet end of the air source pipe 1.

[0038] By setting up air source pipes 1, each air source pipe 1 can spray hot air towards areas where airflow may stagnate or move irregularly at the edge of the shell. The hot air sprayed by the nozzle group 3 disturbs the coal powder particles on the grinding disc 6, causing the coal powder particles to move more towards the air ring 1 of the grinding disc 6 and be blown by the hot air of the air ring 1 towards the air powder outlet 14, thereby reducing the repeated grinding of the coal seam on the grinding disc 6.

[0039] All gas source pipes 1 can be equipped with individual gas input pipes, or they can share a single gas input pipe.

[0040] As a preferred option, all air supply pipes 1 are branches extending from the primary air pipe 12, which reduces the construction difficulty when adding air supply pipes 1, and ensures that the hot air output from air supply pipe 1 and the hot air output from air ring 11 have the same temperature.

[0041] As a preferred option, hot air is introduced into all the gas supply pipes 1 so that the coal powder particles can be dried.

[0042] Example 2

[0043] See Figure 2 and Figure 3 In this embodiment, a certain angle is set between the nozzle group 3 and the grinding roller 5 to avoid directly blowing the coal seam at the bottom of the grinding roller vertically downwards. At the same time, the outward tilt angle should not be too large, so as not to affect the normal upward airflow of the grinding disc air ring. The tilt angle between the nozzle group 3 and the grinding roller makes the airflow ejected from the nozzle group and the upward airflow of the grinding disc air ring form a combined force to move upwards.

[0044] The air source pipe 1 has a horizontal nozzle pipe at the bottom. The nozzle pipe is set in a horizontal direction and a nozzle group 3 is set on the nozzle pipe. This structure allows the nozzles to act in a row between the grinding roller 5 and the grinding disc 6, resulting in a larger working area.

[0045] Example 3

[0046] In this embodiment, each gas source pipe 1 is mounted on a nozzle fixing bracket 4 to stabilize the gas source pipe 1. The nozzle fixing bracket 4 is installed on the medium-speed coal mill.

[0047] Example 4

[0048] In this embodiment, each gas source pipe 1 is equipped with a gas source pipe regulating damper 2. The airflow velocity of the nozzle group can be adjusted according to the output load of the coal mill through the gas source pipe regulating damper. The size of the regulating damper 2 is adjusted to adapt to the output load of the coal mill and improve the output of the coal mill.

[0049] Example 5

[0050] In this embodiment, compared to the above embodiment, there are a total of 3 nozzle groups 3, and the angle between the nozzle groups 3 is 120°. The number of nozzle groups 3 matches the number of grinding rollers 5. The outlet end of each nozzle group 3 includes 4 nozzles, and the nozzle tubes are arranged at equal intervals. All nozzles evenly cover the area where the grinding rollers and grinding disc grind the coal bed.

[0051] Example 6

[0052] In this embodiment, the air source pipe 1 is configured as an inverted U-shaped pipe structure, that is, it is introduced from above behind the grinding roller 5. One end of the air source pipe 1 is connected to the primary air pipe 12, and the output end is located behind the grinding roller 5. This structure ensures that adding the air source pipe 1 will not affect the operation and setup of other equipment.

[0053] The purpose of this invention is to improve the airflow inside a medium-speed coal mill to increase its output. The grinding rollers of the medium-speed coal mill are installed at 120° intervals on the upper part of the grinding disc. The grinding rollers 5 are subjected to necessary grinding pressure using a loading device. When raw coal passes through the grinding rollers 5 and the grinding disc 6, it is ground into coal powder. Dry, hot air carrying away the coal powder enters with the air ring around the rotating grinding disc 6. The hot air carries the coal powder particles and rotates upwards within the grinding space of the coal mill. To improve the carrying capacity of the airflow for coal powder particles inside the coal mill, hot air nozzle groups 3 are added to the roller frames of each 120°-installed grinding roller 5 and the outer edge area of ​​the grinding disc 6. This adds disturbance to the coal bed outside the grinding rollers 5, improving the stagnant or irregular airflow in the edge areas of the coal mill casing, reducing the coal bed thickness, and increasing the output of the coal mill.

[0054] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "transverse," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more. In the description of this utility model, "above" or "below" a second feature may include direct contact between the first and second features, or it may include contact between the first and second features not being in direct contact but through another feature between them.

[0055] In the description of this utility model, the terms "above", "over" and "on top" for the first feature and the second feature include the first feature being directly above or diagonally above the second feature, or simply indicate that the first feature is at a higher horizontal level than the second feature.

[0056] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0057] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0058] Although embodiments of the present invention have been shown and described, those skilled in the art will understand that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the claims and their equivalents.

[0059] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A device for improving the flow of air in a medium speed coal mill to increase the output, characterised in that, The air source pipe (1) is arranged outside each grinding roller (5), and the outlet of the air source pipe (1) is provided with a nozzle group (3); the lower end of the grinding roller (5) is in contact with a grinding disc (6), and the outer side of the grinding disc (6) is provided with an air ring (11) in a circumferential direction; The air outlet direction of the nozzle group (3) is towards the contact position of the grinding roller (5) and the grinding disc (6), and a plurality of nozzles are arranged on the nozzle group (3).

2. A device for improving the performance of a medium speed coal mill according to claim 1, characterized in that, An air source pipe adjusting damper (2) is arranged on each air source pipe (1).

3. A device for improving the performance of a medium speed coal mill as claimed in claim 1, wherein Each air source pipe (1) is fixedly arranged in the medium-speed coal mill through a nozzle fixing support (4).

4. A device for improving the performance of a medium speed coal mill according to claim 1, characterized in that, The air source of all air source pipes (1) is a gas main pipe.

5. A device for improving the performance of a medium speed coal mill according to claim 4, wherein, The gas main pipe is a primary air pipe (12), and the primary air pipe (12) is communicated with the air ring (11).

6. A device for improving the performance of a medium speed coal mill according to claim 1, characterized in that, The air source pipe (1) is a reverse U-shaped pipe.

7. A device for improving the performance of a medium speed coal mill as claimed in claim 1, wherein, A transverse nozzle pipe is arranged at the outlet of the air source pipe (1), the nozzle pipe is arranged in a horizontal direction, and the nozzle group (3) is arranged along the length direction of the nozzle pipe.

8. A device for improving the performance of a medium speed coal mill according to claim 7, characterized in that, A plurality of nozzles are arranged in the nozzle group (3) at equal intervals.

9. A device for improving the performance of a medium speed coal mill according to claim 1, characterized in that, A coal falling pipe (13) is arranged above the grinding disc (6); and a gas powder outlet (14) is arranged above the air ring (11) and the nozzle group (3).

10. The apparatus for improving the output of a medium speed mill from an airflow as claimed in any one of claims 1 to 9, characterised in that, The grinding disc (6) is arranged on a speed reducer (9), the speed reducer (9) is connected with a motor (8), and the motor (8) and the speed reducer (9) are arranged on a coal mill base (10).

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