Anti-accumulation structure and method for pebble coal in inlet air duct of medium-speed coal mill

Abstract

The invention provides an anti-accumulation structure and method for pebble coal in an inlet air duct of a medium-speed coal mill. The anti-accumulation structure comprises an air duct, a first guide plate, a second guide plate and an air nozzle, the air duct comprises a first flow guide part, a second flow guide part and a main body part, and the first end of the first flow guide part is connected with the main body part through the second flow guide part; the second end of the first flow guide part is connected with an inlet of the coal mill; the first flow guide part is obliquely arranged; the multiple first flow guide plates are arranged in the first end of the first flow guide part at intervals; the longitudinal section area of one end, close to the main body part, of the second flow guide part is gradually reduced from the direction close to the main body part to the direction far away from the main body part; a plurality of mounting holes are formed in the bottom wall of the first flow guide part, and each air nozzle is mounted in the corresponding mounting hole. The device has the technical effect that the problem of accumulation of pebble coal in the inlet air duct of the medium-speed coal mill can be effectively solved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal-fired units, and particularly relates to a structure and method for preventing stone coal from piling up in an inlet air duct of a medium-speed coal mill. Background Art

[0002] As the on-site layout of coal-fired units becomes more compact, horizontal special-shaped elbows are widely used at the inlet of medium-speed coal mills. When burning low-quality coal, the coal mill has a large amount of pebble coal. If it is not emptied in time, the pebble coal is very likely to accumulate and enter the coal mill inlet air duct, greatly increasing the air duct resistance. In addition, the pebble coal is prone to spontaneous combustion when it accumulates in the inlet air duct for a long time, creating a safety hazard. In daily operation, the coal mill inlet air duct is closed and wrapped with an insulation layer on the outside. It cannot be inspected in a hot state, and the inside is in a black box state. The accumulation and combustion of pebble coal in the coal mill inlet air duct can easily lead to safety accidents such as the air duct burning through. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art and provide a new technical solution of a structure and method for preventing stone coal from piling up in an inlet air duct of a medium-speed coal mill.

[0004] According to a first aspect of the present invention, a structure for preventing the accumulation of gravel coal in an inlet air duct of a medium-speed coal mill is provided, comprising an air duct, a first guide plate, a second guide plate and an air nozzle; the air duct is hollow inside to form an air flow channel;

[0005] The air duct comprises a first air guide portion, a second air guide portion and a main body portion, wherein a first end of the first air guide portion is connected to the main body portion through the second air guide portion; a second end of the first air guide portion is connected to a coal mill inlet; wherein the main body portion is L-shaped;

[0006] The first guide portion is arranged obliquely, and the height of the second end of the first guide portion is smaller than the height of the first end of the first guide portion;

[0007] A plurality of the first guide plates are disposed at intervals inside the first end of the first guide portion, and each of the first guide plates is arranged along the direction of airflow;

[0008] The longitudinal cross-sectional area of ​​one end of the second guide portion close to the main body portion gradually decreases from a direction close to the main body portion to a direction away from the main body portion;

[0009] A plurality of the second guide plates are spaced apart and arranged inside one end of the second guide portion close to the main body portion;

[0010] A plurality of mounting holes are arranged on the bottom wall of the first air guide portion, and the air nozzle is installed in each of the mounting holes. The air nozzle is used to spray air into the interior of the first air guide portion.

[0011] Optionally, the inclination angle of the first guide portion is not less than 30°.

[0012] Optionally, the first guide plate is arc-shaped.

[0013] Optionally, each of the air nozzles has a semicircular circumferential nozzle.

[0014] Optionally, the bottom surface of the main body is flush with the bottom surface of the second guide portion.

[0015] Optionally, the distance between two adjacent air nozzles is no more than 1 meter.

[0016] Optionally, a bottom surface of the air nozzle is flush with a bottom surface of the first air guide portion.

[0017] Optionally, the pressure of air sprayed by the air nozzle into the interior of the first guide part is not less than 0.8 MPa.

[0018] Optionally, the main body has a vertical bend, and the vertical bend is a rounded transition.

[0019] According to a second aspect of the present invention, a method for preventing pebble coal from piling up in an inlet air duct of a medium-speed coal mill is provided, comprising the following steps:

[0020] When the airflow passes through the main body, the second guide part, the first guide part, and the coal mill inlet in sequence and enters the coal mill, the amount of gravel coal entering the coal mill inlet air duct is reduced by the inclined first guide part; the flow dead zone at the coal mill inlet is reduced by the first guide plate and the second guide plate at the diameter change of the second guide part; and the gravel coal accumulated in the first guide part can be fully cleaned by multiple air nozzles.

[0021] A technical effect of the present invention is:

[0022] In the embodiment of the present application, the first guide portion is arranged at an angle, that is, the air duct at the coal mill inlet is obliquely raised, and the height difference of the interface is utilized to reduce the amount of gravel coal entering the coal mill inlet air duct and reduce the accumulation of gravel coal at the interface position.

[0023] Moreover, multiple first guide plates are spaced apart inside the first end of the first guide part, and multiple second guide plates are spaced apart inside one end of the second guide part close to the main body, thereby realizing segmented flow guidance, reducing the flow dead zone at the coal mill inlet, and reducing the accumulation of stone coal in the local dead zone of the air duct.

[0024] In addition, multiple air nozzles are arranged in the first guide part of the coal mill inlet air duct to realize multi-stage pulse air blowing, which can fully cover and clean the pebble coal accumulated in the air duct, thereby better preventing the pebble coal from accumulating in the medium-speed coal mill inlet air duct. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a front view of a structure for preventing stone coal from piling up in an inlet air duct of a medium-speed coal mill according to an embodiment of the present invention;

[0026] Figure 2 A side view of a structure for preventing stone coal from piling up in an inlet air duct of a medium-speed coal mill according to an embodiment of the present invention;

[0027] Figure 3 It is a schematic diagram of an explosion of a structure for preventing the accumulation of pebble coal in the inlet air duct of a medium-speed coal mill according to an embodiment of the present invention;

[0028] Figure 4 A perspective view of a structure for preventing stone and coal from being deposited in an inlet air duct of a medium-speed coal mill according to an embodiment of the present invention.

[0029] In the figure: 11, first guide part; 111, mounting hole; 12, second guide part; 13, main body; 2, first guide plate; 3, second guide plate; 4, air nozzle; 5, coal mill inlet. DETAILED DESCRIPTION

[0030] 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 of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0031] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as limitations on the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0032] The term "first" or "second" in the specification and claims of this application may include one or more of the features explicitly or implicitly. In the description of this application, unless otherwise specified, "plurality" means two or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / " generally means that the objects connected before and after are in an "or" relationship.

[0033] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0034] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0035] According to a first aspect of the present invention, see Figures 1 to 4 , provides a structure for preventing the accumulation of gravel and coal in the inlet duct of a medium-speed coal mill. It actively prevents blockage by optimizing the bevel connection and segmented flow diversion of the inlet duct of the coal mill, and combines multi-stage pulsed air injection for passive cleaning, thus completely solving the problem of gravel and coal accumulation in the inlet duct of the medium-speed coal mill during hot operation.

[0036] Specifically, the pebble coal accumulation prevention structure of the medium-speed coal mill inlet air duct comprises an air duct, a first guide plate 2, a second guide plate 3 and an air nozzle 4; the air duct is hollow inside to form an air flow channel;

[0037] The air duct includes a first air guide portion 11, a second air guide portion 12 and a main body portion 13, wherein a first end of the first air guide portion 11 is connected to the main body portion 13 through the second air guide portion 12; a second end of the first air guide portion 11 is connected to the coal mill inlet 5; wherein the main body portion 13 is L-shaped;

[0038] The first guide portion 11 is arranged obliquely, and the height of the second end of the first guide portion 11 is smaller than the height of the first end of the first guide portion 11;

[0039] A plurality of the first guide plates 2 are disposed at intervals inside the first end of the first guide portion 11, and each of the first guide plates 2 is arranged along the direction of airflow;

[0040] The longitudinal cross-sectional area of ​​one end of the second guide portion 12 close to the main body portion 13 gradually decreases from the direction close to the main body portion 13 to the direction away from the main body portion 13;

[0041] A plurality of the second guide plates 3 are arranged at intervals inside one end of the second guide portion 12 close to the main body portion 13;

[0042] A plurality of mounting holes 111 are disposed on the bottom wall of the first air guide portion 11 . The air nozzle 4 is mounted in each of the mounting holes 111 . The air nozzle 4 is used to spray air into the interior of the first air guide portion 11 .

[0043] In the embodiment of the present application, the first guide portion 11 is tilted, that is, the air duct at the coal mill inlet 5 is obliquely raised, and the height difference of the interface is utilized to reduce the amount of gravel coal entering the coal mill inlet air duct and reduce the accumulation of gravel coal at the interface position.

[0044] Moreover, multiple first guide plates 2 are spaced apart inside the first end of the first guide part 11, and multiple second guide plates 3 are spaced apart inside one end of the second guide part 12 close to the main body 13, thereby realizing segmented flow guidance, reducing the flow dead zone at the coal mill inlet 5, and reducing the accumulation of stone coal in the local dead zone of the air duct.

[0045] In addition, a plurality of air nozzles 4 are arranged in the first guide part 11 of the coal mill inlet air duct to realize multi-stage pulse air injection, which can fully cover and clean the pebble coal accumulated in the air duct, thereby better preventing the pebble coal from accumulating in the medium-speed coal mill inlet air duct.

[0046] Exemplarily, the air nozzle 4 is a multi-stage pulse air nozzle to better ensure the air blowing effect. The air nozzles 4 are arranged in a staggered manner to achieve the multi-stage pulse air blowing effect.

[0047] Optionally, the inclination angle of the first air guide 11 is not less than 30°. This can effectively reduce the amount of pebble coal entering the coal mill inlet air duct, thereby effectively reducing the accumulation of pebble coal at the interface position.

[0048] Optionally, the first guide plate 2 is arc-shaped, which helps the first guide plate 2 to guide the gas and can effectively reduce the flow dead zone of the coal mill inlet 5.

[0049] Optionally, each of the air nozzles 4 has a semicircular circumferential nozzle, which enables the air nozzle 4 to effectively spray air into the first air guide portion 11, thereby being able to fully cover and clean the pebble coal accumulated in the air duct.

[0050] Optionally, a bottom surface of the main body 13 is flush with a bottom surface of the second air guide portion 12 .

[0051] Optionally, the distance between two adjacent air nozzles 4 is no more than 1 meter. This helps to ensure that each air nozzle 4 has a good blowing effect, so as to fully cover and clean the pebble coal accumulated in the air duct.

[0052] Optionally, the bottom surface of the air nozzle 4 is flush with the bottom surface of the first air guide portion 11. This helps to quickly install the air nozzle 4.

[0053] Optionally, the pressure of the air sprayed by the air nozzle 4 into the first guide part 11 is not less than 0.8 MPa, which better ensures that the air nozzle 4 can fully cover and clean the pebble coal accumulated in the air duct.

[0054] Optionally, the main body 13 has a vertical bend, and the vertical bend is rounded, which helps to achieve smooth flow of air in the main body 13 .

[0055] According to a second aspect of the present invention, a method for preventing pebble coal from piling up in an inlet air duct of a medium-speed coal mill is provided, comprising the following steps:

[0056] When the airflow passes through the main body 13, the second guide part 12, the first guide part 11, and the coal mill inlet 5 in sequence and enters the coal mill, the amount of gravel coal entering the coal mill inlet air duct is reduced by the inclined first guide part 11; the flow dead zone at the coal mill inlet 5 is reduced by the first guide plate 2 and the second guide plate 3 at the diameter change of the second guide part 12; and the gravel coal accumulated in the first guide part 11 can be fully covered and cleaned by multiple air nozzles 4.

[0057] In the above implementation, it is possible to better achieve a complete solution to the problem of stone coal accumulation in the inlet air duct of the medium-speed coal mill during hot operation.

[0058] In a specific implementation method, combined with the inlet air duct of a medium-speed coal mill of a 660MW ultra-supercritical secondary reheat unit, the detailed implementation steps are as follows:

[0059] 1) Determine the inclination angle (i.e., the height of the miter lift) of the first air guide portion 11 of the coal mill inlet air duct according to the on-site space;

[0060] 2) After determining the overall layout of the air duct, perform CFD computational fluid numerical simulation to find out the local flow dead zone of the air duct;

[0061] 3) The coal mill inlet air duct is arranged in a segmented manner and verified by CFD computational fluid numerical simulation to ensure that local flow dead zones are eliminated;

[0062] 4) A mounting hole 111 is provided on the bottom wall of the first air guide portion 11 of the coal mill inlet air duct, and a multi-stage pulse air nozzle 4 is arranged, preferably in a staggered arrangement of 2 to 3 stages;

[0063] 5) Compressed air pipelines are arranged outside the air duct, and a blowing test is carried out with the pressure controlled at 0.8-1Mpa to verify whether the blowing range can fully cover and clean the pebble coal accumulated in the air duct.

[0064] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present invention, but the present invention is not limited thereto. For those of ordinary skill 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 structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill, characterized in that: It includes an air duct, a first guide plate, a second guide plate and an air nozzle; the air duct is hollow inside to form an air flow channel; The air duct comprises a first air guide portion, a second air guide portion and a main body portion, wherein a first end of the first air guide portion is connected to the main body portion through the second air guide portion; a second end of the first air guide portion is connected to a coal mill inlet; wherein the main body portion is L-shaped; The first guide portion is arranged obliquely, and the height of the second end of the first guide portion is smaller than the height of the first end of the first guide portion; A plurality of the first guide plates are disposed at intervals inside the first end of the first guide portion, and each of the first guide plates is arranged along the direction of airflow; The longitudinal cross-sectional area of ​​one end of the second guide portion close to the main body portion gradually decreases from a direction close to the main body portion to a direction away from the main body portion; A plurality of the second guide plates are spaced apart and arranged inside one end of the second guide portion close to the main body portion; A plurality of mounting holes are arranged on the bottom wall of the first air guide portion, and the air nozzle is installed in each of the mounting holes. The air nozzle is used to spray air into the interior of the first air guide portion.

2. The structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill according to claim 1 is characterized in that: The inclination angle of the first guide portion is not less than 30°.

3. The structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill according to claim 1, characterized in that: The first guide plate is arc-shaped.

4. The structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill according to claim 1, characterized in that: Each of the air nozzles has a semicircular circumferential nozzle.

5. The structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill according to claim 1, characterized in that: The bottom surface of the main body is flush with the bottom surface of the second guide portion.

6. The structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill according to claim 1, characterized in that: The distance between two adjacent air nozzles is no more than 1 meter.

7. The structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill according to claim 1, characterized in that: The bottom surface of the air nozzle is flush with the bottom surface of the first air guide portion.

8. The structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill according to claim 1, characterized in that: The pressure of the air sprayed by the air nozzle toward the interior of the first air guide portion is not less than 0.8 MPa.

9. The structure for preventing stone coal from accumulating in the inlet air duct of a medium-speed coal mill according to claim 8, characterized in that: The main body has a vertical bending portion, and the vertical bending portion is rounded transitionally.

10. A method for preventing the accumulation of pebble coal in the inlet air duct of a medium-speed coal mill, characterized in that: The steps include: When the airflow passes through the main body, the second guide part, the first guide part, and the coal mill inlet in sequence and enters the coal mill, the amount of gravel coal entering the coal mill inlet air duct is reduced by the inclined first guide part; the flow dead zone at the coal mill inlet is reduced by the first guide plate and the second guide plate at the diameter change of the second guide part; and the gravel coal accumulated in the first guide part can be fully cleaned by multiple air nozzles.

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