Pulverized coal preparation system for boiler

Abstract

The utility model discloses a pulverized coal preparation system for a boiler, and relates to the technical field of pulverized coal preparation, the pulverized coal preparation system comprises a raw coal bunker, a coal feeder and a coal mill which are communicated in sequence, the coal mill is connected with a mixed air pipeline and a pulverized coal pipeline, and the mixed air pipeline is used for introducing hot primary air and cold primary air into the coal mill; the mixed air pipeline is provided with a mixed air pneumatic slide plate gate, and the pulverized coal pipeline is provided with a pulverized coal pneumatic slide plate gate; the system further comprises a check valve, the check valve is arranged on the pulverized coal pipeline, and when a medium in the pulverized coal pipeline flows to a boiler hearth from the coal mill, the check valve is opened, so that the medium in the pulverized coal pipeline circulates; and when a medium in the pulverized coal pipeline flows to the coal mill from the boiler hearth, the check valve is closed to block the medium circulation in the pulverized coal pipeline, so that personal injury accidents of maintainers during internal maintenance of the coal mill can be effectively prevented, and the personal safety in the internal maintenance process of the coal mill is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of pulverized coal preparation, in particular to a pulverized coal preparation system for a boiler. Background Technique

[0002] A coal mill is a device used to grind coal into qualified pulverized coal for boiler combustion. As a main auxiliary equipment for unit operation, due to reasons such as high unit load and co-firing of some inferior coal types, the overhaul frequency of the coal mill is relatively high.

[0003] At present, during the overhaul of the coal mill, although the safety measures for coal mill overhaul require all pneumatic flap gates at the coal powder outlet of the coal mill (i.e., the quick shut-off valve on the pipeline for feeding coal powder into the boiler) to be closed, however, due to reasons such as the structure of the pneumatic flap gates, the pneumatic flap gates at the hot primary air inlet of the coal mill (i.e., the shut-off valve on the heated primary air pipeline), the pneumatic flap gates at the cold primary air inlet of the coal mill (i.e., the shut-off valve on the unheated primary air pipeline), and the pneumatic flap gates at the mixed air inlet of the coal mill (i.e., the shut-off valve on the pipeline after the mixing of hot primary air and cold primary air) cannot be completely sealed and closed, there is a phenomenon of hot air leakage. Therefore, during the overhaul process, it is necessary to open a group of pneumatic flap gates at the coal mill outlet, and use the negative pressure in the boiler furnace to suck hot air and dust into the furnace interior, so as to create conditions for maintenance personnel to enter the interior of the coal mill for maintenance work.

[0004] However, if the negative pressure in the boiler furnace becomes positive while a group of pneumatic flap gates at the coal mill outlet are opened, the high-temperature flue gas in the boiler will flow back into the coal mill along the coal powder pipeline at the coal mill outlet, resulting in a relatively high safety risk inside the coal mill, severe environmental pollution, and even personal injury accidents to maintenance personnel. Content of the Utility Model

[0005] The purpose of the utility model is to provide a pulverized coal preparation system for a boiler to solve the problems existing in the above-related technologies, which can effectively prevent personal injury accidents of maintenance personnel during the maintenance of the coal mill interior and improve the personal safety during the maintenance process of the coal mill interior.

[0006] To achieve the above purpose, the utility model provides the following scheme:

[0007] The utility model provides a pulverized coal preparation system for a boiler, which includes a raw coal bunker, a coal feeder, and a coal mill connected in sequence. The raw coal bunker is used for storing coal raw materials, the coal feeder is used for conveying the coal raw materials in the raw coal bunker into the coal mill, and the coal mill is used for grinding the coal raw materials into pulverized coal. A mixed air pipeline and a pulverized coal pipeline are connected to the coal mill. The mixed air pipeline is used for introducing hot primary air and cold primary air into the coal mill, so that the pulverized coal in the coal mill is introduced into the boiler furnace through the pulverized coal pipeline. A pneumatic flap valve for mixed air is arranged on the mixed air pipeline, and a pneumatic flap valve for pulverized coal is arranged on the pulverized coal pipeline. The system also includes a check valve, which is arranged on the pulverized coal pipeline. When the medium in the pulverized coal pipeline flows from the coal mill to the boiler furnace, the check valve opens to enable the medium in the pulverized coal pipeline to flow through; when the medium in the pulverized coal pipeline flows from the boiler furnace to the coal mill, the check valve closes to block the flow of the medium in the pulverized coal pipeline.

[0008] Preferably, the check valve includes a central shaft and blades. The central shaft is arranged radially in the pulverized coal pipeline, the blades are rotatably connected to the central shaft, and there are two blades, which are symmetrically arranged on both sides of the central shaft. When the medium in the pulverized coal pipeline flows from the coal mill to the boiler furnace, both blades are folded backward to open the pulverized coal pipeline; when the medium in the pulverized coal pipeline flows from the boiler furnace to the coal mill, both blades are folded forward to close the pulverized coal pipeline.

[0009] Preferably, the check valve further includes a fixing plate and a clamping block. Among them, the fixing plate is fixed on the inner wall of the pulverized coal pipeline, and there are two fixing plates, which are symmetrically arranged in the pulverized coal pipeline. Both ends of the central shaft are fixedly connected to the two fixing plates respectively; the clamping block is fixed on the inner wall of the pulverized coal pipeline, and there are at least two clamping blocks, and the two clamping blocks can be respectively clamped with the front sides of the two blades.

[0010] Preferably, two connecting plates are respectively arranged at both ends of the central shaft, and the two connecting plates are respectively connected to the two fixing plates through bolt fasteners.

[0011] Preferably, a first connecting sleeve and a second connecting sleeve are rotatably sleeved on the central shaft, and the first connecting sleeve and the second connecting sleeve are respectively fixedly connected to the two blades.

[0012] Preferably, there are multiple first connecting sleeves and multiple second connecting sleeves, and each first connecting sleeve and each second connecting sleeve are arranged on the central shaft in an alternating manner.

[0013] Preferably, the rotation angle range of the blade around the central axis is 0° - 85°.

[0014] Preferably, the pulverized coal pipeline is vertically arranged on the pulverized coal outlet of the coal mill, and the check valve is arranged at a position on the pulverized coal pipeline between the pulverized coal outlet of the coal mill and the pneumatic plug valve for pulverized coal.

[0015] Preferably, a throttling orifice is further arranged on the pulverized coal pipeline, and the throttling orifice is arranged at a position on the pulverized coal pipeline behind the pneumatic plug valve for pulverized coal; there are multiple groups of pulverized coal pipelines, and at least one group of pulverized coal pipelines is provided with the check valve.

[0016] Preferably, the pulverized coal preparation system for boilers further includes a pressure sensor and a controller. The pressure sensor and the pneumatic plug valve for pulverized coal are both connected to the controller. The pressure sensor is used to monitor the wind pressure in the boiler furnace, and the controller is used to control the opening and closing of the pneumatic plug valve for pulverized coal.

[0017] The present invention has achieved the following technical effects compared with the related art:

[0018] The pulverized coal preparation system for boilers provided by the present invention includes a raw coal bunker, a coal feeder, and a coal mill that are connected in sequence, and further includes a check valve. The check valve is arranged on the pulverized coal pipeline at the outlet of the coal mill. When the coal mill is operating normally, the check valve is in an open state, and the hot primary air and the cold primary air are introduced into the coal mill through the mixed air pipeline, so that the pulverized coal ground in the coal mill flows through the pulverized coal pipeline to the boiler furnace for combustion; when the coal mill is under maintenance, it is necessary to open the pneumatic plug valve for pulverized coal on the pulverized coal pipeline, and use the negative pressure in the boiler furnace during normal operation of the boiler to draw away the hot air and dust in the coal mill, so that the air in the coal mill circulates, reducing the temperature in the coal mill and facilitating the maintenance personnel to enter the inside of the coal mill for operation. Moreover, because a check valve is arranged on the pulverized coal pipeline, if the boiler furnace suddenly shows a positive pressure, the high-temperature flue gas sent back from the boiler furnace can be blocked from flowing into the coal mill through the check valve, thus ensuring the personal safety of the maintenance personnel in the coal mill. Description of the Drawings

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the related art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0020] Figure 1 It is a schematic diagram of the pulverized coal preparation system for boilers provided by the embodiments of the present invention;

[0021] Figure 2 Schematic diagram of the open state of the check valve provided by the embodiment of the present utility model;

[0022] Figure 3 Schematic diagram of the closed state of the check valve provided by the embodiment of the present utility model.

[0023] In the figure: 1 - raw coal bunker, 2 - coal feeder, 201 - coal feeder seal air pipeline, 3 - coal mill, 301 - coal mill seal air pipeline, 3011 - first seal fan, 3012 - second seal fan, 302 - fire steam pipeline, 303 - slag discharge pipeline, 3031 - slag discharge box, 4 - mixed air pipeline, 401 - pneumatic slide gate for mixed air, 402 - hot primary air pipeline, 4021 - pneumatic slide gate for hot primary air, 403 - cold primary air pipeline, 4031 - pneumatic slide gate for cold primary air, 5 - pulverized coal pipeline, 501 - pneumatic slide gate for pulverized coal, 502 - throttling orifice, 6 - check valve, 601 - central shaft, 602 - blade, 603 - connecting plate. Specific embodiments

[0024] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0025] The purpose of the present utility model is to provide a pulverized coal preparation system for boilers to solve the problems existing in the related technologies, which can effectively prevent personal injury accidents of maintenance personnel during the maintenance inside the coal mill and improve the personal safety during the maintenance process inside the coal mill.

[0026] To make the above objects, features, and advantages of the present utility model more obvious and understandable, the present utility model will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0027] As Figure 1 shown, this embodiment provides a pulverized coal preparation system for boilers, including a raw coal bunker 1, a coal feeder 2, and a coal mill 3 that are connected in sequence. The raw coal bunker 1 is used to hold coal raw materials, the coal feeder 2 is used to convey the coal raw materials in the raw coal bunker 1 into the coal mill 3, and the coal mill 3 is used to grind the coal raw materials into pulverized coal; a mixed air pipeline 4 and a pulverized coal pipeline 5 are connected to the coal mill 3. The mixed air pipeline 4 is used to introduce hot primary air and cold primary air into the coal mill 3, so that the pulverized coal in the coal mill 3 is introduced into the boiler furnace through the pulverized coal pipeline 5. A pneumatic slide gate 401 for mixed air is provided on the mixed air pipeline 4, and a pneumatic slide gate 501 for pulverized coal is provided on the pulverized coal pipeline 5.

[0028] In this embodiment, the system further includes a check valve 6. The check valve 6 is arranged on the pulverized coal pipeline 5. When the medium in the pulverized coal pipeline 5 flows from the coal mill 3 to the boiler furnace, the check valve 6 opens to enable the medium in the pulverized coal pipeline 5 to flow through; when the medium in the pulverized coal pipeline 5 flows from the boiler furnace to the coal mill 3, the check valve 6 closes to block the flow of the medium in the pulverized coal pipeline 5.

[0029] Further, the check valve 6 includes a central shaft 601 and blades 602. The central shaft 601 is arranged radially in the pulverized coal pipeline 5. The blades 602 are rotatably connected to the central shaft 601, and there are two blades 602, and the two blades 602 are symmetrically arranged on both sides of the central shaft 601; specifically, a first connecting sleeve and a second connecting sleeve are rotatably sleeved on the central shaft 601 in this embodiment. The first connecting sleeve and the second connecting sleeve are respectively fixedly connected to the two blades 602, and there are multiple first connecting sleeves and second connecting sleeves. Each first connecting sleeve and each second connecting sleeve are arranged alternately on the central shaft 601, and the rotation angle ranges of the two blades 602 around the central shaft 601 are both 0° - 85°.

[0030] When the medium in the pulverized coal pipeline 5 flows from the coal mill 3 to the boiler furnace, as Figure 2 shown, the two blades 602 are both folded backward (taking the flow direction of the medium in the pulverized coal pipeline 5 from the coal mill 3 to the boiler furnace as the front-to-back direction. At this time, the two blades 602 are both rotated backward until the included angle between them is 10°) to open the pulverized coal pipeline 5; when the medium in the pulverized coal pipeline 5 flows from the boiler furnace to the coal mill 3, as Figure 3 shown, the two blades 602 are both folded forward (that is, on the basis of the check valve 6 being opened, at this time, the two blades 602 are both rotated forward until the included angle between them is 180°) to close the pulverized coal pipeline 5.

[0031] In this embodiment, the check valve 6 further includes a fixing plate and a clamping block. Among them, the fixing plate is fixed on the inner wall of the pulverized coal pipeline 5, and there are two fixing plates. The two fixing plates are symmetrically arranged in the pulverized coal pipeline 5. The two ends of the central shaft 601 are respectively fixedly connected to the two fixing plates; the clamping block is fixed on the inner wall of the pulverized coal pipeline 5, and there are at least two clamping blocks. The two clamping blocks can be respectively clamped with the front sides of the two blades 602 to limit the forward rotation of the two blades 602.

[0032] Further, two connecting plates 603 are respectively arranged at the two ends of the central shaft 601, and the two connecting plates 603 are respectively connected to the two fixing plates through bolt fasteners.

[0033] In this embodiment, the pulverized coal pipeline 5 is vertically arranged at the pulverized coal outlet of the coal mill 3, as Figure 1As shown, the check valve 6 is arranged at a position on the pulverized coal pipeline 5 between the pulverized coal outlet of the coal mill 3 and the pneumatic plug valve 501 of the pulverized coal.

[0034] In this embodiment, a throttle orifice 502 is further arranged on the pulverized coal pipeline 5, and the throttle orifice 502 is arranged at a position on the pulverized coal pipeline 5 behind the pneumatic plug valve 501 of the pulverized coal; there are multiple groups of pulverized coal pipelines 5, and at least one group of pulverized coal pipelines 5 is provided with a check valve 6; since the check valve 6 will still affect the flow area of the pulverized coal pipeline 5 in the open state, therefore, the throttle orifice 502 is designed, and by adjusting the opening degree of the throttle orifice 502, the pulverized coal amount of the pulverized coal pipeline 5 installed with the check valve 6 is made consistent with that of other pulverized coal pipelines 5.

[0035] It should be noted that the blade 602 of the check valve 6 in this embodiment is made of alumina ceramic, and the alumina ceramic material has low density, high temperature resistance, good corrosion resistance, insulation and dielectric properties; the central shaft 601 is made of stainless steel, the middle part of which is a cylinder, and there is a flat plate with a length of 30 mm, a width of 15 mm and a through hole in the center at each end; the check valve 6 in this embodiment is installed in the longitudinally arranged pipeline at the inlet of the pulverized coal pipeline 5 at any outlet of the coal mill 3. The inner diameter of the pulverized coal pipeline 5 is 510 mm, and the wall thickness is 10 mm. Two flat plates with a length of 30 mm and a width of 15 mm and a through hole in the center are symmetrically welded on the inner wall. The two fixing plates are respectively connected with the two connecting plates 603 at both ends of the central shaft 601 of the check valve 6 through bolt fasteners; when the check valve 6 is opened, the two blades 602 can rotate upward by 85° around the central shaft 601. When the check valve 6 is closed, the two blades 602 can return to the horizontal position under the action of their own gravity and the high-temperature flue gas returned from the boiler furnace. The block below the blade 602 can limit the position of the blade 602 and prevent it from rotating downward, so as to realize that when the check valve 6 is in the open state, the fluid before and after the pulverized coal pipeline 5 is connected, and when the check valve 6 is in the closed state, the fluid flow in the pulverized coal pipeline 5 is cut off.

[0036] It should be noted that in the pulverized coal preparation system for boilers provided in this embodiment, a coal feeder sealing air pipeline 201 is also connected to the coal feeder 2; a mill sealing air pipeline 301, a fire steam pipeline 302, and a slag discharge pipeline 303 are also connected to the mill 3. Among them, a normally used and standby first sealing fan 3011 and a second sealing fan 3012 are provided on the mill sealing air pipeline 301, and a slag discharge box 3031 is provided on the slag discharge pipeline 303; the mixed air pipeline 4 connected to the mill 3 is formed by the confluence of a hot primary air pipeline 402 and a cold primary air pipeline 403. A hot primary air pneumatic slide gate 4021 is provided on the hot primary air pipeline 402, and a cold primary air pneumatic slide gate 4031 is provided on the cold primary air pipeline 403; for the above-mentioned conventional settings in this field, they will not be elaborated here.

[0037] The working process of the pulverized coal preparation system for boilers provided in this embodiment is as follows:

[0038] When the mill 3 is running normally, the check valve 6 is in the open state, and the blade 602 is driven to open passively by the positive pressure of the primary air below. The hot primary air and the cold primary air are introduced into the mill 3 through the mixed air pipeline 4, so that the pulverized coal ground in the mill 3 flows to the boiler furnace through the pulverized coal pipeline 5 for combustion. During normal operation, the primary air pressure is about 9 Kpa, and the furnace negative pressure is about -100 Pa.

[0039] When the mill 3 is under maintenance, it is necessary to open the pulverized coal pneumatic slide gate 501 on a group of pulverized coal pipelines 5. After the pulverized coal pneumatic slide gate 501 is opened, due to the negative pressure of the boiler furnace, the blade 602 of the check valve 6 is driven to open upward passively, and the check valve 6 is in the open state. At this time, the hot air and dust in the mill 3 are sucked away by using the furnace negative pressure during the normal operation of the boiler, so that the air in the mill 3 circulates, reducing the temperature in the mill 3 and facilitating the maintenance personnel to enter the inside of the mill 3 for operation.

[0040] During the maintenance process, if the boiler furnace suddenly shows a positive pressure, the blade 602 of the check valve 6 quickly closes under the action of its own gravity and the high-temperature flue gas returned from the boiler furnace, blocking the high-temperature flue gas from flowing into the mill 3, thus ensuring the personal safety of the maintenance personnel in the mill 3.

[0041] At the same time, the pulverized coal preparation system for boilers in this embodiment also includes a pressure sensor and a controller. The pressure sensor and the pulverized coal pneumatic slide gate 501 are both connected to the controller. The pressure sensor is used to monitor the air pressure in the boiler furnace, and the controller is used to control the opening and closing of the pulverized coal pneumatic slide gate 501. That is, by setting a thermal control protection logic device, when the boiler furnace air pressure is +100 Pa, the controller interlocks to close the pulverized coal pneumatic slide gate 501 to double-guarantee to prevent the high-temperature flue gas from returning to the inside of the mill 3.

[0042] In summary, by installing a check valve 6 on the pulverized coal pipeline 5 at the outlet of the coal mill 3, and using the negative pressure in the boiler furnace to suck the hot air and dust inside the coal mill 3 into the furnace, this system fundamentally solves the problems of high temperature and harsh environment inside the coal mill 3. At the same time, it can effectively solve the safety risks and environmental pollution problems of the maintenance personnel inside the coal mill 3.

[0043] In the present utility model, specific examples are used to illustrate the principle and implementation manner of the present utility model. The description of the above embodiments is only used to help understand the method and its core idea of the present utility model; at the same time, for those of ordinary skill in the art, according to the idea of the present utility model, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation on the present utility model.

Claims

1. A pulverized coal preparation system for a boiler, comprising a raw coal bunker, a coal feeder, and a coal mill connected in sequence. The raw coal bunker is used to store coal raw materials, the coal feeder is used to convey the coal raw materials in the raw coal bunker into the coal mill, and the coal mill is used to grind the coal raw materials into pulverized coal. A mixed air pipeline and a pulverized coal pipeline are connected to the coal mill. The mixed air pipeline is used to introduce hot primary air and cold primary air into the coal mill, so that the pulverized coal in the coal mill is introduced into the boiler furnace through the pulverized coal pipeline. A pneumatic slide gate for mixed air is arranged on the mixed air pipeline, and a pneumatic slide gate for pulverized coal is arranged on the pulverized coal pipeline. It is characterized in that: It further includes a check valve, which is arranged on the pulverized coal pipeline. When the medium in the pulverized coal pipeline flows from the coal mill to the boiler furnace, the check valve opens to enable the medium in the pulverized coal pipeline to flow through; when the medium in the pulverized coal pipeline flows from the boiler furnace to the coal mill, the check valve closes to block the flow of the medium in the pulverized coal pipeline.

2. The pulverized coal preparation system for boilers according to claim 1, characterized in that: The check valve includes a central shaft and blades. The central shaft is arranged radially in the pulverized coal pipeline. The blades are rotatably connected to the central shaft, and there are two blades. The two blades are symmetrically arranged on both sides of the central shaft; when the medium in the pulverized coal pipeline flows from the coal mill to the boiler furnace, the two blades both fold backward to open the pulverized coal pipeline; when the medium in the pulverized coal pipeline flows from the boiler furnace to the coal mill, the two blades both fold forward to close the pulverized coal pipeline.

3. The pulverized coal preparation system for boilers according to claim 2, wherein: The check valve further includes fixing plates and clamping blocks. Among them, the fixing plates are fixed on the inner wall of the pulverized coal pipeline, and there are two fixing plates. The two fixing plates are symmetrically arranged in the pulverized coal pipeline. The two ends of the central shaft are respectively fixedly connected to the two fixing plates; the clamping blocks are fixed on the inner wall of the pulverized coal pipeline, and there are at least two clamping blocks. The two clamping blocks can respectively be clamped with the front sides of the two blades.

4. The pulverized coal preparation system for a boiler according to claim 3, characterized in that: Two connecting plates are respectively arranged at the two ends of the central shaft. The two connecting plates are respectively connected to the two fixing plates through bolt fasteners.

5. The pulverized coal preparation system for a boiler according to claim 2, characterized in that: A first connecting sleeve and a second connecting sleeve are rotatably sleeved on the central shaft. The first connecting sleeve and the second connecting sleeve are respectively fixedly connected to the two blades.

6. The pulverized coal preparation system for a boiler according to claim 5, characterized in that: There are multiple first connecting sleeves and multiple second connecting sleeves. Each first connecting sleeve and each second connecting sleeve are arranged on the central shaft in an alternating manner.

7. The pulverized coal preparation system for a boiler according to claim 2, characterized in that: The rotation angle range of the blade around the central shaft is 0° - 85°.

8. The pulverized coal preparation system for boilers according to claim 1, characterized in that: The pulverized coal pipeline is vertically arranged at the pulverized coal outlet of the coal mill. The check valve is arranged at a position on the pulverized coal pipeline between the pulverized coal outlet of the coal mill and the pulverized coal pneumatic plug valve.

9. The pulverized coal preparation system for a boiler according to claim 8, characterized in that: A throttle orifice is further arranged on the pulverized coal pipeline. The throttle orifice is arranged at a position on the pulverized coal pipeline behind the pulverized coal pneumatic plug valve; there are multiple groups of pulverized coal pipelines, and at least one group of pulverized coal pipelines is provided with the check valve.

10. The pulverized coal preparation system for boilers according to claim 1, characterized in that: The boiler pulverized coal preparation system further includes a pressure sensor and a controller. The pressure sensor and the pulverized coal pneumatic plug valve are both connected to the controller. The pressure sensor is used to monitor the wind pressure in the boiler furnace, and the controller is used to control the opening and closing of the pulverized coal pneumatic plug valve.

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