CN219913133U - Pulverized coal combustion device - Google Patents

Abstract

The utility model provides a pulverized coal combustion device, which comprises: the pulverized coal furnace comprises a furnace body; the powder conveying component comprises a storage bin, a powder conveying pipe and a first control valve, wherein an outlet of the storage bin is communicated with an inlet of the powder conveying pipe, and the first control valve is arranged on the powder conveying pipe; the conveying assembly comprises a conveying piece, a conveying pipe and a second control valve, the conveying piece is communicated with the conveying pipe, an outlet of the conveying pipe is communicated with the furnace body, an outlet of the powder conveying pipe is communicated with the conveying pipe, and the second control valve is arranged on the conveying pipe; the powder return assembly comprises a powder return pipe and a third control valve, an inlet of the powder return pipe is communicated with the feeding pipe, an outlet of the powder return pipe is communicated with the storage bin, and the third control valve is arranged on the powder return pipe. According to the technical scheme provided by the utility model, the problem that the coal dust in the feeding pipe remains in the coal dust furnace in the related art when the coal dust furnace is suddenly shut down, and potential safety hazards exist due to the explosion phenomenon caused by increasing the coal dust in the coal dust furnace when the coal dust furnace is restarted can be solved.

Description

Pulverized coal combustion device

Technical Field

The utility model relates to the technical field of pulverized coal furnaces, in particular to a pulverized coal combustion device.

Background

Coal is always the main energy source and important industrial raw material in China, wherein the heating system mainly takes coal as the raw material, and the coal powder furnace is widely applied due to the characteristics of high combustion efficiency, wide conforming adjustment range and easy control of pollutant emission, and the coal is processed into coal powder and introduced into the coal powder furnace to achieve the heating effect.

In the related art, when the pulverized coal furnace works, the conveying fan is communicated with the conveying pipe, and the pulverized coal in the conveying pipe is completely conveyed into the pulverized coal furnace for combustion by controlling the conveying fan to work, so that the pulverized coal in the conveying pipe can enter the pulverized coal furnace and be fully combusted.

However, when the pulverized coal furnace in the related art suddenly stops, the conveying fan stops working, so that pulverized coal can be reserved in the conveying pipe, and when the pulverized coal furnace is started again, the pulverized coal in the pulverized coal furnace is increased to cause a deflagration phenomenon, so that potential safety hazards exist.

Disclosure of Invention

The utility model provides a pulverized coal combustion device, which aims to solve the problem that pulverized coal is reserved in a feeding pipe when a pulverized coal furnace in the related art suddenly stops, and potential safety hazards exist due to the fact that pulverized coal in the pulverized coal furnace is increased when the pulverized coal furnace is restarted.

The utility model provides a pulverized coal combustion device, which comprises: the pulverized coal furnace comprises a furnace body; the powder conveying assembly comprises a storage bin, a powder conveying pipe and a first control valve, wherein an outlet of the storage bin is communicated with an inlet of the powder conveying pipe, and the first control valve is arranged on the powder conveying pipe; the conveying assembly comprises a conveying piece, a conveying pipe and a second control valve, the conveying piece is communicated with the conveying pipe, an outlet of the conveying pipe is communicated with the furnace body, an outlet of the powder conveying pipe is communicated with the conveying pipe, and the second control valve is arranged on the conveying pipe; the powder return assembly comprises a powder return pipe and a third control valve, wherein an inlet of the powder return pipe is communicated with the feeding pipe, an outlet of the powder return pipe is communicated with the storage bin, the third control valve is arranged on the powder return pipe, an inlet of the powder return pipe is positioned at the upstream of the second control valve, and an outlet of the powder conveying pipe is positioned at the upstream of an inlet of the powder return pipe.

Further, the feed tube includes: the powder conveying device comprises a first pipe section, a conveying piece, a powder returning pipe, a powder conveying pipe and a powder conveying pipe, wherein the inlet of the first pipe section is communicated with the conveying piece, the outlet of the first pipe section is communicated with the inlet of the powder returning pipe, and the outlet of the powder conveying pipe is communicated with the first pipe section; the outlet of the first pipe section is communicated with the inlet of the second pipe section, the outlet of the second pipe section is communicated with the furnace body, and the second control valve is arranged on the second pipe section.

Further, the pulverized coal combustion device further comprises a three-way valve, and the outlet of the first pipe section, the inlet of the second pipe section and the inlet of the powder return pipe are respectively communicated with three communication ports of the three-way valve.

Further, the pulverized coal combustion device further comprises a conveyor, the powder conveying pipe comprises a third pipe section and a fourth pipe section, an inlet of the third pipe section is communicated with an outlet of the storage bin, an outlet of the third pipe section is communicated with an inlet of the conveyor, an outlet of the conveyor is communicated with an inlet of the fourth pipe section, an outlet of the fourth pipe section is communicated with the conveying pipe, and the first control valve is arranged on the third pipe section.

Further, the conveyor comprises a weigh screw feeder.

Further, the upper end of the storage bin is provided with a gas outlet, and the gas outlet is provided with a bag-type dust remover for blocking dust.

Further, the powder conveying assembly further comprises a powder inlet pipe, a fourth control valve is arranged at the inlet of the powder inlet pipe, and the outlet of the powder inlet pipe is communicated with the storage bin.

Further, the conveying part comprises a conveying fan, and an air outlet of the conveying fan is communicated with an inlet of the conveying pipe.

Further, the lateral wall of the upper end of storing the storehouse is provided with the intercommunication mouth, and the export and the intercommunication mouth of powder return tube are linked together, and the lower extreme of storing the storehouse is provided with the discharge gate, and the discharge gate communicates with the import of defeated powder pipe.

Further, the first control valve and the second control valve are both pneumatic valves.

By adopting the technical scheme, the pulverized coal combustion device comprises a pulverized coal furnace, a powder conveying component, a conveying component and a powder returning component, wherein a furnace body capable of supplying pulverized coal to burn is arranged in the pulverized coal furnace, the powder conveying component comprises a storage bin, a powder conveying pipe and a first control valve, the storage bin is used for storing pulverized coal, an outlet of the storage bin is communicated with an inlet of the powder conveying pipe, and then pulverized coal in the storage bin can be conveyed through the powder conveying pipe, the powder conveying pipe is communicated with a conveying pipe, and then pulverized coal in the powder conveying pipe can be conveyed into the conveying pipe, a conveying piece is communicated with the conveying pipe, an outlet of the conveying pipe is communicated with the furnace body, and then pulverized coal in the conveying pipe can be conveyed into the furnace body for burning, the powder conveying pipe is provided with the first control valve, the communication between the storage bin and the powder conveying pipe can be controlled or the closed by controlling the opening and closing of the first control valve, and the communication between the conveying pipe and the conveying pipe can be controlled or the closed by controlling the opening and closing of the second control valve. When the pulverized coal furnace suddenly stops, in order to avoid that pulverized coal remains in the conveying pipe, a pulverized coal return assembly is arranged, an inlet of a pulverized coal return pipe in the pulverized coal return assembly is communicated with the conveying pipe, an outlet of the pulverized coal return pipe is communicated with the storage bin, when the furnace is suddenly stopped, the first control valve and the second control valve are closed by control, the third control valve is opened, the conveying piece conveys pulverized coal from the conveying pipe to the pulverized coal return pipe, and then the pulverized coal in the conveying pipe can be conveyed into the storage bin through the pulverized coal return pipe, so that the pulverized coal in the conveying pipe is ensured to be processed, the pulverized coal is prevented from remaining in the conveying pipe, and when the pulverized coal furnace normally works, the first control valve and the second control valve are controlled to be opened, and the third control valve is closed, so that the pulverized coal can be conveyed normally. By adopting the structure, through the pulverized coal furnace, the powder conveying component, the conveying component and the powder returning component are mutually matched, when the pulverized coal furnace works normally, the first control valve and the second control valve are opened through control, the third control valve is closed, the pulverized coal in the storage bin can be conveyed into the furnace body through the powder conveying pipe and the conveying pipe, the conveying effect can be guaranteed, when the pulverized coal furnace is suddenly shut down, the first control valve and the second control valve are closed, the third control valve is opened, the conveying part can convey the pulverized coal into the pulverized coal bin through the powder returning pipe, and the deflagration phenomenon caused by the increase of the pulverized coal in the pulverized coal furnace is avoided.

Drawings

The accompanying drawings, which are included to provide a further understanding of the utility model and are incorporated in and constitute a part of this specification, illustrate embodiments of the utility model and together with the description serve to explain the utility model. In the drawings:

fig. 1 shows a schematic diagram of a pulverized coal combustion device according to an embodiment of the present utility model.

Wherein the above figures include the following reference numerals:

10. a pulverized coal furnace; 11. a furnace body;

20. a powder conveying component; 21. a storage bin; 211. a bag-type dust collector; 212. a communication port; 213. a discharge port; 22. a powder conveying pipe; 221. a third pipe section; 222. a fourth pipe section; 23. a first control valve; 24. a powder inlet pipe; 25. a fourth control valve;

30. a transport assembly; 31. a conveying member; 311. a conveying fan; 32. a feed pipe; 321. a first pipe section; 322. a second pipe section; 33. a second control valve;

40. a powder return assembly; 41. a powder return pipe; 42. a third control valve;

50. a three-way valve; 60. and a conveyor.

Detailed Description

The following description of the embodiments of the present utility model will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present utility model, but not all embodiments. The following description of at least one exemplary embodiment is merely exemplary in nature and is in no way intended to limit the utility model, its application, or uses. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

As shown in fig. 1, an embodiment of the present utility model provides a pulverized coal combustion device, the pulverized coal combustion device includes a pulverized coal furnace 10, a pulverized coal conveying component 20, a conveying component 30 and a pulverized coal return component 40, the pulverized coal furnace 10 includes a furnace body 11, the pulverized coal conveying component 20 includes a storage bin 21, a pulverized coal conveying pipe 22 and a first control valve 23, an outlet of the storage bin 21 is communicated with an inlet of the pulverized coal conveying pipe 22, the first control valve 23 is disposed on the pulverized coal conveying pipe 22, the conveying component 30 includes a conveying member 31, a conveying pipe 32 and a second control valve 33, the conveying member 31 is communicated with the conveying pipe 32, an outlet of the conveying pipe 32 is communicated with the furnace body 11, an outlet of the conveying pipe 22 is communicated with the conveying pipe 32, the second control valve 33 is disposed on the conveying pipe 32, an inlet of the pulverized coal return component 40 includes a pulverized coal return pipe 41 and a third control valve 42, an outlet of the pulverized coal return pipe 41 is communicated with the storage bin 21, the third control valve 42 is disposed on the pulverized coal return pipe 41, an inlet of the pulverized coal return pipe 41 is located upstream of the second control valve 33, and an outlet of the pulverized coal return pipe 22 is located upstream of the pulverized coal return pipe 41.

The pulverized coal combustion device provided by the embodiment is applied, the pulverized coal combustion device comprises a pulverized coal furnace 10, a powder conveying component 20, a conveying component 30 and a powder returning component 40, a furnace body 11 which can be used for pulverized coal combustion is arranged in the pulverized coal furnace 10, the powder conveying component 20 comprises a storage bin 21, a powder conveying pipe 22 and a first control valve 23, the storage bin 21 is used for storing pulverized coal, an outlet of the storage bin 21 is communicated with an inlet of the pulverized coal pipe, pulverized coal in the storage bin 21 can be conveyed through the powder conveying pipe 22, the powder conveying pipe 22 is communicated with a conveying pipe 32, pulverized coal in the pulverized coal pipe can be conveyed into the conveying pipe 32, a conveying piece 31 is communicated with the conveying pipe 32, an outlet of the conveying pipe 32 is communicated with the furnace body 11, the pulverized coal in the conveying pipe 32 can be conveyed into the furnace body 11 through the conveying piece 31, the first control valve 23 is arranged on the powder conveying pipe 22, communication between the storage bin 21 and the powder conveying pipe 22 or closing can be controlled through controlling the opening and closing of the furnace body 23, and the second control valve 33 is arranged on the conveying pipe 32, and the conveying pipe 32 can be communicated with the conveying pipe 11 through the opening and closing of the second control valve 33. When the pulverized coal furnace 10 suddenly stops, in order to avoid that pulverized coal remains in the conveying pipe 32, a pulverized coal return assembly 40 is arranged, an inlet of a pulverized coal return pipe 41 in the pulverized coal return assembly 40 is communicated with the conveying pipe 32, an outlet of the pulverized coal return pipe 41 is communicated with the storage bin 21, when the pulverized coal furnace is suddenly stopped, the first control valve 23 and the second control valve 33 are controlled to be closed, the third control valve 42 is opened, the conveying member 31 conveys pulverized coal to the pulverized coal return pipe 41 from the conveying pipe 32, and then the pulverized coal in the conveying pipe 32 can be conveyed into the storage bin 21 through the pulverized coal return pipe 41, so that the pulverized coal in the conveying pipe 32 is ensured to be processed, the pulverized coal remains in the conveying pipe 32, and when the pulverized coal furnace 10 normally works, the first control valve 23 and the second control valve 33 are controlled to be opened, and the third control valve 42 is controlled to be closed, so that the pulverized coal can be conveyed normally into the furnace body 11. With the above structure, through the cooperation of the pulverized coal furnace 10, the powder conveying component 20, the conveying component 30 and the powder returning component 40, when the pulverized coal furnace 10 works normally, the first control valve 23 and the second control valve 33 are opened by control, the third control valve 42 is closed, the pulverized coal in the storage bin 21 can be conveyed into the furnace body 11 through the powder conveying pipe 22 and the conveying pipe 32, the conveying effect is ensured, when the pulverized coal furnace 10 is suddenly stopped, in order to clean the pulverized coal in the conveying pipe 32, the first control valve 23 and the second control valve 33 are closed, the third control valve 42 is opened, the conveying component 31 can convey the pulverized coal into the pulverized coal bin through the powder returning pipe 41, and the phenomenon of deflagration caused by the increase of the pulverized coal in the pulverized coal furnace 10 is avoided.

As shown in fig. 1, the feeding pipe 32 includes a first pipe section 321 and a second pipe section 322, an inlet of the first pipe section 321 is communicated with the conveying member 31, an outlet of the first pipe section 321 is communicated with an inlet of the powder return pipe 41, an outlet of the powder conveying pipe 22 is communicated with the first pipe section 321, an outlet of the first pipe section 321 and an inlet of the powder return pipe 41 are respectively communicated with an inlet of the second pipe section 322, an outlet of the second pipe section 322 is communicated with the furnace body 11, and the second control valve 33 is provided on the second pipe section 322. With the above structure, by arranging the first pipe section 321 and the second pipe section 322, the inlet of the first pipe section 321 is communicated with the conveying member 31, the outlet of the first pipe section 321 is communicated with the inlet of the powder returning pipe 41, the outlet of the powder conveying pipe 22 is communicated with the first pipe section 321, and the outlet of the first pipe section 321 and the inlet of the powder returning pipe 41 are respectively communicated with the inlet of the second pipe section 322, so that the first pipe section 321, the second pipe section 322 and the powder returning pipe 41 can be communicated, the second control valve 33 is arranged on the second pipe section 322, the opening and closing of the second control valve 33 can be controlled, and when the pulverized coal furnace 10 is suddenly shut down, the third control valve 42 is opened, so that pulverized coal in the conveying pipe 32 can be conveyed into the storage bin 21 through the powder returning pipe 41, the pulverized coal is prevented from being conveyed into the furnace body 11 through the second pipe section 322, normal operation can be ensured when the pulverized coal furnace 10 is opened again, and the phenomenon of knocking of the pulverized coal furnace 10 is avoided.

As shown in fig. 1, the pulverized coal combustion apparatus further includes a three-way valve 50, and an outlet of the first pipe section 321, an inlet of the second pipe section 322, and an inlet of the pulverized coal return pipe 41 are respectively communicated with three communication ports 212 of the three-way valve 50. With the above structure, by providing the three-way valve 50, the first pipe section 321, the second pipe section 322, and the return pipe 41 are facilitated to be communicated.

As shown in fig. 1, the pulverized coal combustion device further comprises a conveyor 60, the pulverized coal conveying pipe 22 comprises a third pipe section 221 and a fourth pipe section 222, an inlet of the third pipe section 221 is communicated with an outlet of the storage bin 21, an outlet of the third pipe section 221 is communicated with an inlet of the conveyor 60, an outlet of the conveyor 60 is communicated with an inlet of the fourth pipe section 222, an outlet of the fourth pipe section 222 is communicated with the conveying pipe 32, and the first control valve 23 is arranged on the third pipe section 221. By adopting the above structure, the conveyor 60 is arranged between the third pipe section 221 and the fourth pipe section 222 to transport the pulverized coal, the first control valve 23 is arranged on the third pipe section 221, and then the pulverized coal in the storage bin 21 can be conveniently transported, and the transport efficiency can be improved by using the conveyor 60 for transport.

In this embodiment, the conveyor 60 comprises a weigh screw feeder. By adopting the structure, the weighing type screw feeder is arranged, the opening degree of the first control valve 23 is controlled, the coal dust quantity conveyed to the weighing type screw feeder can be controlled, and the weighing type screw feeder can quantitatively convey the coal dust quantity according to the load of the furnace body 11.

As shown in fig. 1, the upper end of the storage bin 21 is provided with a gas outlet, and the gas outlet is provided with a bag-type dust remover 211 for blocking dust. With the above structure, by providing the gas outlet, the pulverized coal can be exhausted by the gas outlet when being conveyed by the conveying member 31, and the bag dust remover 211 is arranged at the gas outlet to prevent the pulverized coal from being discharged through the gas outlet, so that the dust removing effect can be achieved, and the pulverized coal can be prevented from being discharged out of the storage bin 21 through the gas outlet.

As shown in fig. 1, the powder conveying assembly 20 further comprises a powder inlet pipe 24, the inlet of the powder inlet pipe 24 is provided with a fourth control valve 25, and the outlet of the powder inlet pipe 24 is communicated with the storage bin 21. By adopting the structure, through setting up into the powder pipe 24, advance the powder pipe 24 and can communicate with the buggy car, advance the powder pipe 24 and can communicate the buggy car with storing the storehouse 21, and then can supply the buggy in the storehouse 21 to advance the import of powder pipe 24 and set up fourth control valve 25, can be through the switching of control fourth control valve 25 and then control the buggy car and store the storehouse 21 and communicate, guarantee to transport the buggy.

As shown in fig. 1, the conveying member 31 includes a conveying fan 311, and an air outlet of the conveying fan 311 communicates with an inlet of the feed pipe 32. With the structure, the conveying fan 311 is arranged, so that the conveying fan 311 is convenient for conveying the pulverized coal in the conveying pipe 32.

As shown in fig. 1, the side wall of the upper end of the storage bin 21 is provided with a communication port 212, the outlet of the powder return pipe 41 is communicated with the communication port 212, the lower end of the storage bin 21 is provided with a discharge port 213, and the discharge port 213 is communicated with the inlet of the powder conveying pipe 22. By adopting the structure, the communicating port 212 is formed in the side wall of the storage bin 21, the powder return pipe 41 is conveniently communicated with the storage bin 21 through the communicating port 212, and the discharge port 213 is formed, so that the storage bin 21 is communicated with the powder conveying pipe 22, the pulverized coal can be conveyed, and the pulverized coal can be prevented from being left in the conveying pipe 32.

In the present embodiment, the first control valve 23 and the second control valve 33 are both pneumatic valves. By adopting the structure, the first control valve 23 and the second control valve 33 are pneumatic valves, so that the first control valve 23 and the second control valve 33 can be automatically controlled conveniently, and the structure is ensured to be reliable.

The device provided by the embodiment has the following beneficial effects:

(1) Through the mutual cooperation of the pulverized coal furnace 10, the powder conveying assembly 20, the conveying assembly 30 and the powder returning assembly 40, when the pulverized coal furnace 10 works normally, the first control valve 23 and the second control valve 33 are controlled to be opened, the third control valve 42 is closed, the pulverized coal in the storage bin 21 can be conveyed into the furnace body 11 through the powder conveying pipe 22 and the conveying pipe 32, the conveying effect can be ensured, when the pulverized coal furnace 10 is suddenly shut down, in order to clean the pulverized coal in the conveying pipe 32, the first control valve 23 and the second control valve 33 are closed, the third control valve 42 is opened, the conveying member 31 can convey the pulverized coal into the pulverized coal bin through the powder returning pipe 41, and the phenomenon of deflagration caused by the increase of the pulverized coal in the pulverized coal furnace 10 is avoided;

(2) By arranging the third pipe section 221 and the fourth pipe section 222, the conveyor 60 is arranged between the third pipe section 221 and the fourth pipe section 222 to transport the pulverized coal, and the first control valve 23 is arranged on the third pipe section 221, so that the pulverized coal in the storage bin 21 can be conveniently transported, and the transportation efficiency can be improved by using the conveyor 60 for transportation;

(3) By providing the gas outlet, the gas outlet can be utilized to exhaust gas when the conveying member 31 is utilized to convey the pulverized coal, and in order to avoid the pulverized coal from being discharged through the gas outlet, the bag-type dust collector 211 is arranged at the gas outlet, so that the dust removing effect can be achieved, and the pulverized coal can be prevented from being discharged out of the storage bin 21 through the gas outlet.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the present utility model. As used herein, the singular is also intended to include the plural unless the context clearly indicates otherwise, and furthermore, it is to be understood that the terms "comprises" and/or "comprising" when used in this specification are taken to specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof.

The relative arrangement of the components and steps, numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present utility model unless it is specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective parts shown in the drawings are not drawn in actual scale for convenience of description. Techniques, methods, and apparatus known to one of ordinary skill in the relevant art may not be discussed in detail, but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any specific values should be construed as merely illustrative, and not a limitation. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further discussion thereof is necessary in subsequent figures.

In the description of the present utility model, it should be understood that the azimuth or positional relationships indicated by the azimuth terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal", and "top, bottom", etc., are generally based on the azimuth or positional relationships shown in the drawings, merely to facilitate description of the present utility model and simplify the description, and these azimuth terms do not indicate and imply that the apparatus or elements referred to must have a specific azimuth or be constructed and operated in a specific azimuth, and thus should not be construed as limiting the scope of protection of the present utility model; the orientation word "inner and outer" refers to inner and outer relative to the contour of the respective component itself.

Spatially relative terms, such as "above … …," "above … …," "upper surface at … …," "above," and the like, may be used herein for ease of description to describe one device or feature's spatial location relative to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "above" or "over" other devices or structures would then be oriented "below" or "beneath" the other devices or structures. Thus, the exemplary term "above … …" may include both orientations of "above … …" and "below … …". The device may also be positioned in other different ways (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

In addition, the terms "first", "second", etc. are used to define the components, and are only for convenience of distinguishing the corresponding components, and the terms have no special meaning unless otherwise stated, and therefore should not be construed as limiting the scope of the present utility model.

The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

Claims (10)

1. A pulverized coal combustion device, characterized in that the pulverized coal combustion device comprises:

a pulverized coal furnace (10) comprising a furnace body (11);

the powder conveying assembly (20) comprises a storage bin (21), a powder conveying pipe (22) and a first control valve (23), wherein an outlet of the storage bin (21) is communicated with an inlet of the powder conveying pipe (22), and the first control valve (23) is arranged on the powder conveying pipe (22);

the conveying assembly (30) comprises a conveying piece (31), a conveying pipe (32) and a second control valve (33), wherein the conveying piece (31) is communicated with the conveying pipe (32), an outlet of the conveying pipe (32) is communicated with the furnace body (11), an outlet of the powder conveying pipe (22) is communicated with the conveying pipe (32), and the second control valve (33) is arranged on the conveying pipe (32);

the powder return assembly (40) comprises a powder return pipe (41) and a third control valve (42), wherein an inlet of the powder return pipe (41) is communicated with the feeding pipe (32), an outlet of the powder return pipe (41) is communicated with the storage bin (21), the third control valve (42) is arranged on the powder return pipe (41), an inlet of the powder return pipe (41) is located at the upstream of the second control valve (33), and an outlet of the powder conveying pipe (22) is located at the upstream of an inlet of the powder return pipe (41).

2. Pulverized coal burner as claimed in claim 1, characterized in that the feed pipe (32) comprises:

a first pipe section (321), wherein an inlet of the first pipe section (321) is communicated with the conveying piece (31), an outlet of the first pipe section (321) is communicated with an inlet of the powder return pipe (41), and an outlet of the powder conveying pipe (22) is communicated with the first pipe section (321);

the second pipe section (322), the export of first pipe section (321) with the import of powder return pipe (41) respectively with the import intercommunication of second pipe section (322), the export of second pipe section (322) with furnace body (11) intercommunication, second control valve (33) set up on second pipe section (322).

3. The pulverized coal combustion device according to claim 2, characterized in that the pulverized coal combustion device further comprises a three-way valve (50), and the outlet of the first pipe section (321), the inlet of the second pipe section (322) and the inlet of the pulverized coal return pipe (41) are respectively communicated with three communication ports (212) of the three-way valve (50).

4. The pulverized coal combustion device according to claim 1, characterized in that the pulverized coal combustion device further comprises a conveyor (60), the pulverized coal conveying pipe (22) comprises a third pipe section (221) and a fourth pipe section (222), an inlet of the third pipe section (221) is communicated with an outlet of the storage bin (21), an outlet of the third pipe section (221) is communicated with an inlet of the conveyor (60), an outlet of the conveyor (60) is communicated with an inlet of the fourth pipe section (222), an outlet of the fourth pipe section (222) is communicated with the feeding pipe (32), and the first control valve (23) is arranged on the third pipe section (221).

5. The pulverized coal combustion device according to claim 4, characterized in that the conveyor (60) comprises a weighing screw feeder.

6. Pulverized coal combustion device according to claim 1, characterized in that the upper end of the storage bin (21) is provided with a gas outlet with a bag-type dust collector (211) for blocking dust.

7. The pulverized coal combustion device according to claim 1, characterized in that the powder conveying assembly (20) further comprises a powder inlet pipe (24), a fourth control valve (25) is arranged at an inlet of the powder inlet pipe (24), and an outlet of the powder inlet pipe (24) is communicated with the storage bin (21).

8. Pulverized coal burner as claimed in claim 1, characterized in that the conveying member (31) comprises a conveying fan (311), the air outlet of the conveying fan (311) being in communication with the inlet of the feed pipe (32).

9. The pulverized coal combustion device according to claim 1, characterized in that a communication port (212) is arranged on the side wall of the upper end of the storage bin (21), the outlet of the powder return pipe (41) is communicated with the communication port (212), a discharge port (213) is arranged on the lower end of the storage bin (21), and the discharge port (213) is communicated with the inlet of the powder conveying pipe (22).

10. Pulverized coal combustion device according to claim 1, characterized in that the first control valve (23) and the second control valve (33) are both pneumatic valves.