A device and method for improving the uniformity of powder output from the outlet pipe of a medium-speed coal mill.

Abstract

This invention provides an apparatus and method for improving the uniformity of coal powder output from the outlet pipe of a medium-speed coal mill. The apparatus includes a coal mill cylinder, an inner cone, separating blades, flow equalization blocks, a venturi structure, and an outlet pipe. The inner cone is disposed on the upper inner side of the coal mill cylinder, and a coal powder movement channel is formed between the outer wall of the inner cone and the inner wall of the coal mill cylinder. Multiple separating blades are evenly distributed circumferentially along the top of the inner cone. Each separating blade has a preset torsion angle, and a separation channel is formed between adjacent separating blades. Multiple flow equalization blocks are evenly distributed circumferentially along the top of the inner wall of the coal mill cylinder. The venturi structure is disposed at the top outlet of the coal mill cylinder, with its input end connected to the separation channel and its output end connected to the outlet pipe. One technical advantage of this invention is its reasonable design, which significantly improves the uniformity of coal powder output from the outlet pipe of a medium-speed coal mill.

Description

Technical Field

[0001] This invention belongs to the field of energy conservation and consumption reduction technology for coal-fired power plants, and specifically relates to a device and method for improving the uniformity of powder quantity in the outlet pulverizer of a medium-speed coal mill. Background Technology

[0002] For coal-fired power boilers, the uniformity of pulverized coal concentration distribution is a core issue, directly affecting the proper organization of boiler combustion and the uniformity of boiler heat load. It is a prerequisite for solving a series of problems such as combustion deviation, steam temperature deviation, wall temperature deviation, and high-temperature corrosion. Medium-speed coal mills are widely used in coal-fired power boiler units and are the most common pulverizing and feeding equipment, accounting for over 80% of the industry. Therefore, the uniformity of pulverized coal distribution at the outlet pipe of the medium-speed coal mill is crucial, determining the overall boiler operating efficiency in the coal-fired power sector and playing a fundamental role in the efficient, safe, and economical operation of coal-fired units.

[0003] Numerous practical application cases and test results show that the maximum deviation of pulverized coal quantity at the outlet tube of medium-speed coal mills is over 30%, with some deviations reaching nearly 100%. Significant differences in pulverized coal fineness also exist between different tubes, causing obvious uneven combustion problems in the boilers and greatly affecting the efficient and flexible operation of coal-fired power units. Existing boilers in major coal-fired power plants all suffer from pulverized coal quantity deviation at the outlet tube of medium-speed coal mills, posing a significant challenge to boiler combustion operation adjustments.

[0004] Therefore, there is an urgent need for a device and method to improve the uniformity of powder quantity at the outlet of a medium-speed coal mill, in order to solve the aforementioned problem of powder quantity deviation at the outlet of a medium-speed coal mill. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art, and to provide a new technical solution for a device and method for improving the uniformity of powder quantity in the outlet powder pipe of a medium-speed coal mill.

[0006] According to a first aspect of the present invention, an apparatus for improving the uniformity of powder quantity at the outlet of a medium-speed coal mill is provided, comprising:

[0007] The coal mill cylinder and the inner cone are provided. The inner cone is located on the upper inner side of the coal mill cylinder. The outer side wall of the inner cone and the inner side wall of the coal mill cylinder form a coal powder movement channel.

[0008] Separating blades, a plurality of separating blades are evenly distributed circumferentially along the top of the inner cone; each separating blade has a preset torsion angle; a separation channel is formed between adjacent separating blades;

[0009] The flow equalization blocks are evenly distributed circumferentially along the top of the inner side wall of the coal mill cylinder;

[0010] The venturi structure and the outlet powder pipe are provided. The multiple outlet powder pipes are all arranged above the coal mill cylinder. The top outlet of the coal mill cylinder is provided with the venturi structure. The input end of the venturi structure is connected to the separation channel, and the output end is connected to the outlet powder pipe.

[0011] When the air-coal mixture moves from bottom to top along the motion channel inside the rotating coal mill cylinder, it is uniformly mixed under the flow equalization effect of the flow equalization block and then enters the separation channel and passes through the Venturi structure to enter the outlet powder pipe; wherein, the separation blade generates an airflow rotation effect on the air-coal mixture, making the coal powder more dispersed in space.

[0012] Optionally, each of the separating blades has a preset bending angle.

[0013] Optionally, the torsion angle is 30°; the bending angle is 150°.

[0014] Optionally, the torsion angle is 30°.

[0015] Optionally, the flow equalization block includes a first part and a second part, the first part being located below the second part, and the first part being semi-conical in shape, while the second part being semi-cylindrical in shape.

[0016] As the air-powder mixture moves through the motion channel, it passes sequentially through the conical surface of the first part and the cylindrical surface of the second part.

[0017] Optionally, the top surface height of the separating blade is higher than the top surface height of the flow equalization block, and the bottom surface height of the separating blade is higher than the top surface height of the flow equalization block.

[0018] Optionally, the device for improving the uniformity of powder quantity at the outlet of the medium-speed coal mill further includes a grinding roller and a grinding bowl, both of which are located below the inner cone, with the bottom of the inner cone facing the center of the grinding bowl;

[0019] The grinding roller and grinding bowl work together to grind the raw coal into coal powder.

[0020] Optionally, the device for improving the uniformity of powder quantity at the outlet of the medium-speed coal mill also includes a coal drop pipe;

[0021] One end of the coal chute extends along the central axis of the inner cone, and the powder outlet of the coal chute faces the middle of the grinding bowl.

[0022] According to a second aspect of the present invention, a method for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill is provided, employing the apparatus for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill as described in the first aspect, comprising the following steps:

[0023] The raw coal blocks fall freely through the coal chute to the center of the uniformly rotating grinding bowl. During the rotation of the grinding bowl, the raw coal blocks move from the center of the grinding bowl to the gap between the grinding roller and the grinding bowl under the action of friction and centrifugal force.

[0024] As the grinding bowl rotates, the grinding rollers rotate under the friction of the raw coal blocks, and the coal blocks are crushed into coal powder by the grinding rollers.

[0025] Driven by a primary airflow, pulverized coal is conveyed upwards and separated sequentially by the flow equalization effect of the flow equalization block and the airflow rotation effect of the separation blades. The separated pulverized coal is then conveyed to the outlet pulverized coal pipe through the Venturi structure.

[0026] Optionally, as the air-powder mixture passes through the separating blades, the separating blades simultaneously bend the air-powder mixture.

[0027] One technical advantage of this invention is that:

[0028] In this embodiment of the application, before the air-powder mixture enters the separation channel, the air-powder mixture is evenly distributed by the flow equalization effect of the flow equalization block, which greatly improves the uniformity of powder distribution in the coal mill outlet powder pipe.

[0029] Furthermore, when the air-coal mixture enters the separation channel, the separation blades generate an airflow rotation effect on the air-coal mixture, which can reduce the occurrence of airflow short-circuiting. This makes the coal powder flowing out of the separation channel more dispersed in space, thereby improving the uniformity of coal powder distribution at the outlet pipe. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of a device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to an embodiment of the present invention.

[0031] Figure 2 This is a schematic diagram of the separation blades of a device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill, according to an embodiment of the present invention.

[0032] Figure 3 This is a schematic diagram of the separation blades of a device for improving the uniformity of powder quantity in the outlet powder pipe of a medium-speed coal mill, according to another embodiment of the present invention.

[0033] Figure 4 This is a schematic diagram of the flow equalization block of a device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to an embodiment of the present invention.

[0034] Figure 5 This is a cross-sectional schematic diagram of a device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to an embodiment of the present invention.

[0035] Figure 6 This is a schematic diagram comparing the powder quantity deviation of different powder tubes before and after structural improvement according to an embodiment of the present invention;

[0036] Figure 7 This is a schematic diagram showing the powder distribution in the powder tube below the separating blade according to an embodiment of the present invention;

[0037] Figure 8 This represents the trajectory of coal powder particles inside an existing coal mill.

[0038] In the diagram: 1. Coal mill cylinder; 2. Inner cone; 3. Separating blades; 4. Flow equalization block; 41. First part; 42. Second part; 5. Venturi structure; 6. Outlet powder pipe; 7. Grinding roller; 8. Grinding bowl; 9. Coal drop pipe; 10. Primary air duct; 11. Gearbox. Detailed Implementation

[0039] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0040] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated 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 application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0041] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0042] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application 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 application.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" 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 between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] According to a first aspect of the invention, see Figures 1 to 5 A medium-speed reference is provided. Figure 4 A device for improving the uniformity of coal powder output at the coal mill outlet includes:

[0045] The coal mill cylinder 1 and the inner cone 2 are provided. The inner cone 2 is located on the upper inner side of the coal mill cylinder 1. The outer side wall of the inner cone 2 and the inner side wall of the coal mill cylinder 1 form a coal powder movement channel.

[0046] Separating blades 3, a plurality of separating blades 3 are evenly distributed circumferentially along the top of the inner cone 2; each separating blade 3 has a preset torsion angle; a separation channel is formed between adjacent separating blades 3;

[0047] The flow equalization block 4, a plurality of the flow equalization blocks 4 are evenly distributed circumferentially along the top of the inner sidewall of the coal mill cylinder 1;

[0048] The Venturi structure 5 and the outlet powder pipe 6 are provided. The multiple outlet powder pipes 6 are all arranged above the coal mill cylinder 1. The Venturi structure 5 is provided at the top outlet of the coal mill cylinder 1. The input end of the Venturi structure 5 is connected to the separation channel, and the output end is connected to the outlet powder pipe 6.

[0049] When the air-coal mixture moves from bottom to top along the motion channel inside the rotating coal mill cylinder 1, it is uniformly mixed under the flow equalization effect of the flow equalization block 4 and then enters the separation channel and passes through the Venturi structure 5 to enter the outlet powder pipe 6; wherein, the separation blade 3 generates an airflow rotation effect on the air-coal mixture, making the coal powder more dispersed in space.

[0050] In this embodiment of the application, before the air-powder mixture enters the separation channel, the air-powder mixture is evenly distributed by the flow equalization block 4, which greatly improves the uniformity of powder distribution in the coal mill outlet powder pipe.

[0051] Furthermore, when the air-powder mixture enters the separation channel, the separation blades 3 generate an airflow rotation effect on the air-powder mixture, which can reduce the occurrence of airflow short-circuiting, thereby making the coal powder flowing out of the separation channel more dispersed in space, thus achieving the purpose of improving the uniformity of coal powder distribution in the outlet coal pipe 6.

[0052] It should be noted that the root cause of the powder quantity deviation at the outlet of the medium-speed coal mill in the coal-fired power boiler lies in the highly uneven gas-solid two-phase flow inside the coal mill. The uneven coal powder concentration inside the coal mill leads to a significant powder quantity deviation at the outlet of the coal mill. Therefore, to effectively solve the powder quantity deviation problem, it is necessary to start from the inside of the coal mill. By optimizing the internal flow field of the coal mill, the mixing effect of the coal powder concentration inside the mill can be enhanced, and the uniformity of the gas-solid two-phase flow distribution inside the coal mill can be improved, thereby improving the uniformity of the powder quantity distribution at the outlet of the coal mill.

[0053] This embodiment of the application starts from the inside of the coal mill. By arranging flow equalization blocks 4 in the same height area as the separation blades 3 at the top of the coal mill cylinder 1, and changing the shape of the separation blades 3, the uniformity of air-coal distribution at the coal mill outlet is greatly improved. This does not require changing the external structural arrangement of the coal mill. Solving the coal powder concentration deviation from the inside of the coal mill can fundamentally solve a major "pain point" problem in the coal power industry.

[0054] It should be emphasized that the asymmetry between the single-sided air intake of the existing coal mill, the arrangement of the primary air duct, and the distribution of the grinding rollers 7 is the reason for the uneven distribution of coal powder carried by the primary air along the circumferential and radial directions. As a result, the coal powder entering the separation channel is unevenly distributed, which further leads to a large distribution deviation when the coal powder enters each outlet powder pipe 6 from the top of the separation channel.

[0055] By observing the movement trajectory of pulverized coal particles inside the coal mill, the causes of uneven pulverized coal distribution can be revealed, such as... Figure 8 As shown. Due to the presence of the grinding roller 7, the air-powder mixture in the grinding zone is obstructed by the grinding roller 7 and divided into three streams, resulting in an uneven state of the air-powder mixture entering the separation channel.

[0056] Therefore, in this application, to improve the air-coal distribution characteristics of the medium-speed coal mill, it is necessary to reduce the impact of the distinctly divided air-coal mixture into three streams between the mill cylinder 1 and the inner cone 2 on the air-coal mixture entering the outlet powder pipe 6. Based on this, multiple flow-equalizing blocks 4 are evenly distributed circumferentially along the top of the inner wall of the mill cylinder 1 to ensure that the air-coal mixture is distributed as evenly as possible before entering the separation channel through the flow-equalizing effect of the guide blocks. The number of guide blocks can be specifically determined by the flow field optimization effect.

[0057] Furthermore, the separating blades 3 are arranged at the top of the coal mill, serving to separate qualified coal powder and mix the air-coal-solid two-phase flow. This has a crucial impact on obtaining ideal coal powder fineness, coal powder uniformity index, and powder quantity deviation in the coal mill. Therefore, this application further improves the powder quantity distribution deviation of the coal mill outlet powder pipe 6 by optimizing and upgrading the separating blades 3.

[0058] For example, the separating blade 3 is located at the top of the coal mill and at the inlet of the outlet powder pipe 6. Qualified coal powder is separated by the separating blade 3 and enters the outlet powder pipe 6, while unqualified coal powder flows down through the inner cone and enters the inside of the coal mill for secondary grinding.

[0059] Optionally, see Figure 2 The twist angle is 30°. This causes the separating blade 3 to form a twisted blade structure, which enhances the airflow mixing effect inside the separating channel, thereby making the coal powder particles more evenly distributed in space.

[0060] In other implementations, see Figure 3 Each of the separating blades 3 has a preset bending angle. This causes the separating blades 3 to form a twisted blade structure, which significantly enhances the two-phase flow swirling effect inside the separation channel, significantly reduces airflow short-circuiting, and enhances the airflow mixing effect inside the separation channel, thereby making the coal powder particles more uniformly distributed in space.

[0061] Optionally, the torsion angle is 30°; the bending angle is 150°. This significantly improves the uniformity of the spatial distribution of pulverized coal particles.

[0062] Optionally, the flow equalization block 4 includes a first part 41 and a second part 42, the first part 41 is located below the second part 42, and the first part 41 is in the shape of a semi-cone, while the second part 42 is in the shape of a semi-cylinder.

[0063] When the air-powder mixture moves through the motion channel, it passes sequentially through the conical surface of the first part 41 and the cylindrical surface of the second part 42.

[0064] In the above embodiments, the flow equalization block 4 has a reasonable structural design. The flow equalization effect of the flow equalization block 4 makes the air-powder mixture evenly distributed, which greatly improves the uniformity of powder distribution in the coal mill outlet powder pipe.

[0065] Optionally, the top surface height of the separating blade 3 is higher than the top surface height of the flow equalization block 4, and the bottom surface height of the separating blade 3 is higher than the top surface height of the flow equalization block 4. This helps to improve the uniformity of the air-coal mixture distribution, thereby greatly improving the uniformity of the coal mill outlet powder pipe powder distribution.

[0066] For example, a planetary gear is installed inside the reduction gearbox 11. The reduction gearbox 11 is directly connected to the grinding bowl 8 and has an appropriate reduction ratio so that the grinding bowl 8 can reach the required speed and ensure the stability of the rotation of the grinding bowl 8.

[0067] In one embodiment, three separate spring-loaded units are located above the three grinding bowls 8. When the raw coal fills the gap between the grinding roller 7 and the grinding bowl 8, each grinding roller 7 can rotate freely under the action of the spring.

[0068] Optionally, the device for improving the uniformity of powder quantity at the outlet of the medium-speed coal mill also includes a grinding roller 7 and a grinding bowl 8, wherein the grinding roller 7 and the grinding bowl 8 are both located below the inner cone 2, and the bottom of the inner cone 2 faces the middle of the grinding bowl 8.

[0069] The grinding roller 7 and grinding bowl 8 work together to grind the raw coal blocks and form coal powder.

[0070] In the above embodiments, the raw coal blocks can be ground into coal powder of a preset fineness by the cooperation of the grinding roller 7 and the grinding bowl 8.

[0071] Optionally, the device for improving the uniformity of powder quantity at the outlet of the medium-speed coal mill also includes a coal drop pipe 9;

[0072] One end of the coal drop pipe 9 extends along the central axis inside the inner cone 2, and the powder outlet of the coal drop pipe 9 faces the middle of the grinding bowl 8.

[0073] In the above embodiment, the raw coal blocks can be smoothly added into the inside of the coal mill cylinder 1 through the coal drop pipe 9, which facilitates the grinding of the grinding roller 7 and the grinding bowl 8.

[0074] In this embodiment, after separation by the separating blades 3, coal powder particles that do not meet the fineness requirements fall back onto the grinding bowl 8 through the inner cone 2 for re-grinding, while coal powder particles that meet the requirements are carried into the outlet of the coal mill venturi structure 5 by the primary air, and then sent to the boiler furnace for combustion through the outlet powder pipe 6.

[0075] It should be added that as the grinding bowl 8 rotates, the grinding roller 7 rotates under the friction of the raw coal, and the coal is crushed by the grinding roller 7 into pulverized coal that meets the requirements of boiler combustion. At the same time, primary air flows into the primary air chamber of the coal mill from the primary air duct connected to the bottom of the mill at a certain speed, and then the air pressure and velocity increase sharply when passing through the air ring. Under the action of centrifugal force, the pulverized coal moves to the upper part of the air outlet of the air ring on the outer edge of the grinding bowl 8. Driven by the primary air, the finer pulverized coal is conveyed upward; foreign matter mixed in with the raw coal and non-combustible materials such as copper and iron ore (e.g., coarse coal) fall directly into the primary air chamber through the air ring, and are then swept into the coarse coal outlet by the rotation of the scraper device. The coarser pulverized coal particles conveyed upward fall back onto the grinding bowl 8 for secondary grinding under their own gravity and collision with the guide device.

[0076] According to a second aspect of the present invention, a method for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill is provided, employing the apparatus for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill as described in the first aspect, comprising the following steps:

[0077] The raw coal block falls freely through the coal drop pipe 9 to the middle of the uniformly rotating grinding bowl 8. During the rotation of the grinding bowl 8, the raw coal block moves from the middle of the grinding bowl 8 to the gap between the grinding roller 7 and the grinding bowl 8 under the action of friction and centrifugal force.

[0078] As the grinding bowl 8 rotates, the grinding roller 7 rotates under the friction of the raw coal block, and the coal block is crushed into coal powder by the grinding roller 7.

[0079] Driven by a primary airflow, the pulverized coal is conveyed upwards and separated sequentially by the flow equalization action of the flow equalization block 4 and the airflow rotation action of the separation blades 3. The separated pulverized coal is then conveyed to the outlet pulverized coal pipe 6 via the Venturi structure 5.

[0080] In the above embodiments, the method for improving the uniformity of powder quantity at the outlet of the medium-speed coal mill is reasonably designed and can greatly improve the uniformity of powder quantity distribution at the outlet of the coal mill.

[0081] Optionally, as the air-coal mixture passes through the separation blade 3, the separation blade 3 simultaneously bends the air-coal mixture. This significantly enhances the two-phase flow swirl effect inside the separation channel, significantly reduces airflow short-circuiting, and enhances airflow mixing inside the separation channel, thereby making the coal powder particles more evenly distributed in space.

[0082] Taking the device with 4 outlet powder pipes 6 as an example, Figure 6 The figure shows the powder quantity deviation of each powder pipe (i.e., outlet powder pipe 6) before and after the device improvement caused by setting the flow guide block. As can be seen from the figure, the powder quantity deviation of each outlet powder pipe 6 is significantly improved after setting the flow guide block.

[0083] Specifically, before the structural improvement, the coal powder quality deviation in each pulverizer pipe was large, and the deviation of the coal powder quantity in the four pulverizer pipes was discrete. The difference in coal powder quantity deviation between the pulverizer pipes was significant under different operating conditions. Among them, the maximum coal powder quality deviation of pulverizer pipes 1 and 2 was -27.4% and -30.7%, respectively, while the maximum coal powder quality deviation of pulverizer pipes 3 and 4 reached 34.2% and 55.2%, respectively. Under different mill output conditions, the range of coal powder quality deviation for pulverizer pipes 1, 2, 3, and 4 was -29.9% to -27.3%, -30.7% to -14.2%, 5.8% to 34.2%, and 8.6% to 55.2%, respectively. After improving the device by setting up guide blocks, the coal powder quality deviation of each pulverizer pipe was significantly reduced. Under the operating conditions of each coal mill, the coal powder quality deviation ranges of powder pipes 1, 2, 3, and 4 are -9.1% to -2.8%, -6.6% to 5.2%, -3.7% to 8.0%, and 1.6% to 10.2%, respectively. It can be seen that the maximum deviation of powder quantity in each powder pipe is about 10%, and the uniformity of powder quantity distribution in the powder pipes is significantly improved.

[0084] Figure 7 The distribution of powder quantity deviation in the coal mill outlet pipe under different structural configurations of the separating blade 3 is shown. Clearly, when the separating blade 3 has a straight blade structure, the powder quantity deviations obtained from numerical simulation for the four pipes are -16.2%, -2.8%, 26.2%, and -7.2%, respectively, while the corresponding experimental powder quantity deviations are -14.4%, -8.0%, 30.9%, and -8.6%, respectively. It is evident that with a straight blade structure, the airflow rotation effect is relatively poor, and the airflow mixing effect within the separation channel is relatively poor, which easily leads to airflow short-circuiting and causes a large deviation in the coal powder quantity at the pulverizer outlet. When the separation blade 3 is a twisted blade structure or a bent-twisted blade structure, the two-phase flow swirling effect inside the separation channel is significantly enhanced, the airflow short-circuiting situation is significantly reduced, and the airflow mixing effect inside the separation channel is enhanced, resulting in a more uniform spatial distribution of coal powder particles. Moreover, with the twisted blade structure or the bent-twisted blade structure, the absolute value of the powder quantity deviation at each outlet pulverizer 6 remains within 9.5%, and especially when the twisted blade structure is used, the absolute value of the powder quantity deviation at each outlet pulverizer 6 is within 4.3%, indicating that the twisted blade structure has a more significant effect on improving the uniformity of powder quantity.

[0085] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill, characterized in that, include: The coal mill cylinder and the inner cone are provided. The inner cone is located on the upper inner side of the coal mill cylinder. The outer side wall of the inner cone and the inner side wall of the coal mill cylinder form a coal powder movement channel. Separating blades, a plurality of separating blades are evenly distributed circumferentially along the top of the inner cone; each separating blade has a preset torsion angle and a preset bending angle, so that the separating blades form a twisted blade structure; a separation channel is formed between adjacent separating blades; The flow equalization blocks are evenly distributed circumferentially along the top of the inner side wall of the coal mill cylinder; the top surface height of the separation blade is higher than the top surface height of the flow equalization blocks, and the bottom surface height of the separation blade is lower than the top surface height of the flow equalization blocks. The venturi structure and the outlet powder pipe are provided. The multiple outlet powder pipes are all arranged above the coal mill cylinder. The top outlet of the coal mill cylinder is provided with the venturi structure. The input end of the venturi structure is connected to the separation channel, and the output end is connected to the outlet powder pipe. When the air-coal mixture moves from bottom to top along the motion channel inside the coal mill cylinder, it is uniformly mixed under the flow equalization effect of the flow equalization block and then enters the separation channel and passes through the Venturi structure to enter the outlet powder pipe; wherein, the separation blade generates an airflow rotation effect on the air-coal mixture, making the coal powder more dispersed in space.

2. The device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to claim 1, characterized in that, The torsion angle is 30°; the bending angle is 150°.

3. The device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to claim 1, characterized in that, The twist angle is 30°.

4. The device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to claim 1, characterized in that, The flow equalization block includes a first part and a second part, the first part being located below the second part, and the first part being semi-conical in shape, while the second part being semi-cylindrical in shape. As the air-powder mixture moves through the motion channel, it passes sequentially through the conical surface of the first part and the cylindrical surface of the second part.

5. The device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to claim 3, characterized in that, It also includes a grinding roller and a grinding bowl, both of which are disposed below the inner cone, with the bottom of the inner cone facing the middle of the grinding bowl; The grinding roller and grinding bowl work together to grind the raw coal into coal powder.

6. The device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to claim 5, characterized in that, It also includes the coal chutes; One end of the coal chute extends along the central axis inside the inner cone, and the powder outlet of the coal chute faces the middle of the grinding bowl.

7. A method for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill, characterized in that, The device for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill as described in any one of claims 1 to 6 includes the following steps: The raw coal blocks fall freely through the coal chute to the center of the uniformly rotating grinding bowl. During the rotation of the grinding bowl, the raw coal blocks move from the center of the grinding bowl to the gap between the grinding roller and the grinding bowl under the action of friction and centrifugal force. As the grinding bowl rotates, the grinding rollers rotate under the friction of the raw coal blocks, and the coal blocks are crushed into coal powder by the grinding rollers. Driven by a primary airflow, pulverized coal is conveyed upwards and separated sequentially by the flow equalization effect of the flow equalization block and the airflow rotation effect of the separation blades. The separated pulverized coal is then conveyed to the outlet pulverized coal pipe through the Venturi structure.

8. The method for improving the uniformity of powder quantity at the outlet pipe of a medium-speed coal mill according to claim 7, characterized in that, As the air-powder mixture passes through the separating blades, the separating blades simultaneously bend the air-powder mixture.

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