Anti-channeling efficient air inlet system for coal drop pipe of circulating fluidized bed boiler

Abstract

The invention discloses an anti-channeling efficient air inlet system for a coal drop pipe of a circulating fluidized bed boiler, which comprises a hearth, the coal drop pipe and an air inlet pipe, and the coal drop pipe comprises an inclined coal pipe and a vertical coal pipe; the air inlet pipe comprises a main pipe, a first branch pipe, a second branch pipe and a third branch pipe. According to the anti-backflow efficient air inlet system for the coal drop pipe of the circulating fluidized bed boiler, high-temperature flue gas is prevented from flowing backwards, so that potential safety hazards are reduced, and the risk that spontaneous combustion and other unsafe incidents are possibly caused is avoided. By means of the air cushion buffering effect formed in the second branch pipe, the situation that wet coal directly impacts the pipe wall to adhere to and block the coal falling pipe is effectively prevented, and smooth conveying of the coal is guaranteed. And the coal spreading air of the first branch pipe accelerates the conveying of the coal as fired, so that the combustion efficiency is improved. On the whole, the system reduces the influence of the positive pressure of the hearth on the coal drop pipe, optimizes the operating environment in the boiler, and is beneficial to stable operation of the boiler.

Description

Technical Field

[0001] This invention relates to the field of circulating fluidized bed boiler technology, and specifically to an anti-backflow high-efficiency air intake system for the coal chutes of a circulating fluidized bed boiler. Background Technology

[0002] With the rapid development of my country's economy and technology, circulating fluidized bed (CFB) boiler technology has been widely applied, achieving a leap from subcritical to supercritical and ultra-supercritical. my country has become the country with the largest installed capacity of CFB boilers in the world, with more than 4,000 supercritical / ultra-supercritical CFB boilers in operation, including 69 CFB boilers with a capacity of 300MW or more. However, during the operation of large CFB boilers, especially in models with large evaporation capacities (such as 130t / h and above), the coal inlet at the bottom of the furnace is usually under positive pressure, which can easily lead to the following problems: high-temperature flue gas can easily backflow from the coal inlet to equipment such as the coal feeder, posing a safety hazard. The combined effect of positive pressure in the furnace and coal churn results in insufficient coal feeding air pressure head, causing some coal feeding air to backflow into the vertical coal chute and coal feeder, spreading coal dust in the incoming coal into the external space, which can easily cause unsafe incidents such as spontaneous combustion. Summary of the Invention

[0003] The present invention aims to at least partially solve one of the technical problems in the related art.

[0004] Therefore, embodiments of the present invention propose an efficient air intake system for preventing backflow in the coal chutes of a circulating fluidized bed boiler.

[0005] The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to embodiments of the present invention includes a furnace, a coal chute, and an air intake pipe. The coal chute includes an inclined coal pipe and a vertical coal pipe. The first end of the inclined coal pipe is connected to the furnace, and the second end of the inclined coal pipe gradually slopes upward in a direction away from the furnace. The vertical coal pipe is arranged vertically on the inclined coal pipe and communicates with the inclined coal pipe. The air inlet pipe includes a main pipe, a first branch pipe, a second branch pipe, and a third branch pipe. The first branch pipe is connected to the second end of the inclined coal pipe and conveys coal-spreading air along the axial direction of the inclined coal pipe. The second branch pipe is located upstream of the vertical coal pipe and is connected to the inclined coal pipe. The second branch pipe is used to convey coal-spreading air along the axial direction of the inclined coal pipe and toward the inner wall surface of the inclined coal pipe. The third branch pipe is located downstream of the vertical coal pipe and is connected to the inclined coal pipe. The third branch pipe is used to convey coal-spreading air toward the first end of the inclined coal pipe.

[0006] In some embodiments, the anti-backflow high-efficiency air intake system for the coal chutes of a circulating fluidized bed boiler according to the present invention further includes a first fan, a second fan, an air preheater, a first air duct and a second air duct. The first fan is connected to the inlet of the air preheater, and the outlet of the air preheater is connected to the air intake duct through the first air duct to deliver hot primary air into the main duct. The second fan is connected to the main duct through the second air duct to deliver room temperature air into the main duct.

[0007] In some embodiments, the difference between the air pressure of the second blower and the air pressure of the hot secondary air in the furnace is greater than or equal to 3 kPa.

[0008] In some embodiments, the first air duct is provided with a first flow regulating valve, and the second air duct is provided with a second flow regulating valve.

[0009] In some embodiments, the diameter of the inclined coal pipe is D1, and the diameter of the third branch pipe is D2, wherein 1 / 3 ≤ D2 / D1 ≤ 1.

[0010] In some embodiments, the anti-backflow high-efficiency air intake system for the coal chutes of a circulating fluidized bed boiler according to the present invention further includes a guide plate, which is disposed inside the inclined coal chutes and is set at an angle to the axis of the inclined coal chutes.

[0011] In some embodiments, the inclined coal pipe has a coal drop outlet communicating with the vertical coal pipe, and the guide plate is located at the coal drop outlet. In a projection plane orthogonal to the axis of the vertical coal pipe, at least a portion of the projection of the guide plate is located within the projection of the coal drop outlet.

[0012] In some embodiments, the first end of the guide plate is located upstream of the coal inlet and connected to the top wall of the inclined coal pipe, and the second end of the guide plate gradually slopes downward along the direction from the second end of the inclined coal pipe toward the first end of the inclined coal pipe.

[0013] In some embodiments, the projection of the axis of the inclined coal pipe lies within the projection of the guide plate in a projection plane orthogonal to the axis of the inclined coal pipe.

[0014] In some embodiments, the first branch pipe is provided with a first control valve, the second branch pipe is provided with a second control valve, and the third branch pipe is provided with a third control valve.

[0015] The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers, as described in this invention, reduces safety hazards and avoids the risk of spontaneous combustion and other unsafe events by preventing high-temperature flue gas backflow. The air cushion effect formed in the second branch pipe effectively prevents wet coal from sticking to and clogging the coal chutes due to direct impact with the pipe wall, ensuring smooth coal transport. The coal-feeding air in the first branch pipe accelerates the transport of coal into the furnace, improving combustion efficiency. Overall, this system reduces the impact of positive pressure in the furnace on the coal chutes, optimizes the internal operating environment of the boiler, and contributes to the stable operation of the boiler. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the anti-backflow high-efficiency air intake system according to an embodiment of the present invention.

[0017] Figure label: 100. Anti-backflow high-efficiency air intake system; 1. Furnace; 2. Coal chute; 201. Inclined coal chute; 2011. Coal chute opening; 202. Vertical coal chute; 3. Air intake pipe; 301. Main pipe; 302. First branch pipe; 303. Second branch pipe; 304. Third branch pipe; 4. First air conveying pipe; 5. Second air conveying pipe; 6. First flow regulating valve; 7. Second flow regulating valve; 8. Guide plate; 9. First control valve; 10. Second control valve; 11. Third control valve. Detailed Implementation

[0018] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0019] like Figure 1 As shown, the anti-backflow high-efficiency air intake system 100 for the coal chute of a circulating fluidized bed boiler according to an embodiment of the present invention includes a furnace 1, a coal chute 2, and an air intake pipe 3. The coal chute 2 includes an inclined coal pipe 201 and a vertical coal pipe 202. The first end of the inclined coal pipe 201 is connected to the furnace 1, and the second end of the inclined coal pipe 201 gradually slopes upward in a direction away from the furnace 1. The vertical coal pipe 202 is arranged vertically above the inclined coal pipe 201 and communicates with the inclined coal pipe 201.

[0020] The air inlet duct 3 includes a main pipe 301, a first branch pipe 302, a second branch pipe 303, and a third branch pipe 304. The first branch pipe 302 is connected to the second end of the inclined coal pipe 201 and conveys air for spreading coal along the axial direction of the inclined coal pipe 201. The second branch pipe 303 is located upstream of the vertical coal pipe 202 and is connected to the inclined coal pipe 201. The second branch pipe 303 is used to convey air for spreading coal along the axial direction of the inclined coal pipe 201 and toward the inner wall surface of the inclined coal pipe 201. The third branch pipe 304 is located downstream of the vertical coal pipe 202 and is connected to the inclined coal pipe 201. The third branch pipe 304 is used to convey air for spreading coal toward the first end of the inclined coal pipe 201.

[0021] This invention relates to an efficient anti-backflow air intake system 100 for a circulating fluidized bed boiler coal chute 2. The coal chute 2 consists of an inclined coal pipe 201 and a vertical coal pipe 202. One end of the inclined coal pipe 201 is connected to the furnace 1, and the other end gradually slopes upwards. This reduces coal accumulation and adhesion within the pipe and facilitates smooth coal transport. The main pipe 301 distributes the airflow to the various branch pipes. The first branch pipe 302 connects to the second end of the inclined coal pipe 201 and its main function is to accelerate the transport of coal into the furnace, enabling it to quickly enter the furnace 1. The second branch pipe 303 is located upstream of the vertical coal pipe 202, and its coal-spreading air acts as an air cushion to buffer the direct impact of wet coal on the wall of the inclined coal pipe 201, reducing the risk of adhesion and blockage. The third branch pipe 304 is located downstream of the vertical coal pipe 202, and its coal-spreading air acts as a counteracting force against the positive pressure within the furnace 1, preventing high-temperature flue gas from backflowing into the coal chute 2.

[0022] The anti-backflow high-efficiency air intake system 100 for the coal chutes of a circulating fluidized bed boiler, as described in this embodiment, reduces safety hazards and avoids the risk of spontaneous combustion and other unsafe events by preventing the backflow of high-temperature flue gas. The air cushion buffer formed in the second branch pipe 303 effectively prevents wet coal from sticking to and clogging the coal chutes 2 due to direct impact with the pipe wall, ensuring smooth coal transport. The coal-feeding air in the first branch pipe 302 accelerates the transport of coal into the furnace, improving combustion efficiency. Overall, this system reduces the impact of the positive pressure in the furnace 1 on the coal chutes 2, optimizes the internal operating environment of the boiler, and contributes to the stable operation of the boiler.

[0023] In some embodiments, the anti-backflow high-efficiency air intake system 100 for the coal chute of a circulating fluidized bed boiler according to this invention further includes a first fan (not shown in the figure), a second fan (not shown in the figure), an air preheater (not shown in the figure), a first air duct 4, and a second air duct 5. The first fan is connected to the inlet of the air preheater, and the outlet of the air preheater is connected to the inlet duct 3 through the first air duct 4 to deliver hot primary air into the main duct 301. The second fan is connected to the main duct 301 through the second air duct 5 to deliver room temperature air into the main duct 301.

[0024] The first fan is connected to the inlet of the air preheater, and its main function is to draw air and send it into the air preheater. This ensures sufficient airflow through the preheater for heating the air. The air preheater is a heat exchange device that uses the waste heat from the boiler flue gas to heat the air. The heated air (called hot primary air) improves combustion efficiency because preheated air increases the oxygen content in the furnace, thereby promoting complete fuel combustion. The first air duct 4 connects the outlet of the air preheater and the main pipe 301 of the inlet air duct 3. It is responsible for delivering the preheated hot primary air to the main pipe 301 of the inlet air system. In this way, the hot primary air can be distributed to the branch pipes according to design requirements, playing its role in accelerating coal transportation and preventing flue gas backflow.

[0025] The second air fan is connected to the main air pipe 301 via the second air duct 5, and its main function is to supply room temperature air into the main air pipe 301. This air is typically used to regulate the inlet air temperature and flow rate to meet the boiler's needs under different operating conditions. The second air duct 5 is responsible for delivering the room temperature air supplied by the second air fan to the main air pipe 301 of the inlet air system. In this way, the system can mix hot primary air and room temperature air as needed to achieve optimal combustion performance.

[0026] Preheating air significantly increases combustion temperature, promoting more complete fuel combustion and thus improving overall boiler efficiency. By supplying air at different temperatures to the system, the temperature and oxygen concentration during combustion can be flexibly adjusted to adapt to various boiler operating conditions. This system enables better control of pressure and combustion processes within the furnace, thereby optimizing boiler performance and reducing pollutant emissions. Improved combustion efficiency reduces fuel consumption, lowers operating costs, and enhances the boiler's economic viability.

[0027] In some embodiments, the difference between the air pressure of the second fan and the air pressure of the hot secondary air in the furnace 1 is greater than or equal to 3 kPa, which is used to cope with the positive pressure of the boiler under high boiler load conditions.

[0028] During high-load operation, the boiler's combustion intensity increases, potentially raising the pressure within furnace 1 and making positive pressure more pronounced. In this situation, higher air pressure is required to prevent hot flue gas from backflowing into the coal chute 2 within furnace 1. At high loads, pressure fluctuations within furnace 1 may be greater; increasing the air pressure of the second blower helps maintain combustion stability and prevents combustion instability caused by pressure fluctuations. Preventing hot flue gas backflow is crucial for ensuring the boiler's safe operation. Increasing the air pressure differential enhances the boiler's resistance to positive pressure in furnace 1, reducing safety accidents caused by positive pressure.

[0029] Therefore, by ensuring that the pressure difference between the second blower and the hot secondary air is greater than or equal to 3 kPa, backflow of flue gas caused by positive pressure in furnace 1 can be effectively prevented, reducing safety hazards. During high-load operation, adjusting the pressure of the second blower allows for more flexible control of the pressure within furnace 1, maintaining a stable combustion process. An appropriate pressure difference helps optimize combustion, improve combustion efficiency, and reduce energy waste and pollutant emissions caused by incomplete combustion.

[0030] In some embodiments, a first flow regulating valve 6 is provided on the first air supply pipe 4, and a second flow regulating valve 7 is provided on the second air supply pipe 5, for switching the source of coal feeding air and controlling the flow rate of coal feeding air according to the boiler status.

[0031] The first flow regulating valve 6 and the second flow regulating valve 7 can switch the source of the coal-feeding air according to the real-time needs of the boiler. For example, when the boiler needs more hot primary air, the flow rate of the hot primary air can be increased through the regulating valve, while when a temperature reduction is needed, the flow rate of room temperature air can be increased. These regulating valves can precisely control the flow rate of the coal-feeding air, ensuring that the boiler receives an appropriate amount of air under different operating conditions, which is crucial for maintaining combustion efficiency and safety.

[0032] In some embodiments, the diameter of the inclined coal pipe 201 is D1, and the diameter of the third branch pipe 304 is D2, where 1 / 3 ≤ D2 / D1 ≤ 1. By setting the ratio of D2 / D1, it can be ensured that the air volume provided by the third branch pipe 304 is sufficient to resist the positive pressure of the furnace 1 and prevent flue gas from backflowing into the coal drop pipe 2. During boiler operation, the reasonable allocation of air volume to different branch pipes is crucial for maintaining combustion efficiency and safety. By controlling the pipe diameter ratio, the optimized allocation of air volume can be achieved.

[0033] In some embodiments, the anti-backflow high-efficiency air intake system 100 for the coal chutes of a circulating fluidized bed boiler according to the present invention further includes a guide plate 8, which is disposed inside the inclined coal pipe 201 and is set at an angle to the axis of the inclined coal pipe 201.

[0034] The guide vane 8 is designed at an angle to the axis of the inclined coal pipe 201, which accelerates the coal-spreading air passing through the inclined coal pipe 201, enabling it to carry pulverized coal more effectively. The accelerated coal-spreading air generates a stronger airflow, which helps to entrain pulverized coal, allowing it to enter the furnace 1 directly instead of depositing in the coal drop pipe 2. By directly entraining pulverized coal into the furnace 1, the loss of pulverized coal in the coal drop pipe 2 can be reduced, improving combustion efficiency.

[0035] In some embodiments, the wall of the inclined coal pipe 201 has a coal drop port 2011 communicating with the vertical coal pipe 202, and the guide plate 8 is located at the coal drop port 2011. In a projection plane orthogonal to the axis of the vertical coal pipe 202, at least a portion of the projection of the guide plate 8 is located within the projection of the coal drop port 2011.

[0036] The baffle plate 8 is designed to prevent backflow of coal feeding air into the vertical coal feed pipe, ensuring that the airflow follows the designed direction. Located at the coal inlet 2011, the baffle plate 8 guides the airflow and pulverized coal directly into the furnace 1, rather than into the coal feeder or other equipment. The baffle plate 8 helps optimize the distribution of pulverized coal at the coal inlet 2011, ensuring that the pulverized coal enters the furnace 1 evenly and improving combustion efficiency.

[0037] In some embodiments, the first end of the guide plate 8 is located upstream of the coal inlet 2011 and connected to the top wall of the inclined coal pipe 201, and the second end of the guide plate 8 gradually slopes downward along the direction from the second end of the inclined coal pipe 201 toward the first end of the inclined coal pipe 201.

[0038] The first end of the guide plate 8 is located upstream of the coal inlet 2011 and connected to the top wall of the inclined coal pipe 201. This allows for more effective guidance of airflow and pulverized coal, ensuring they flow along the designed path. The second end of the guide plate 8 gradually slopes downwards from the second end of the inclined coal pipe 201 towards the first end. This design helps form an airflow barrier, preventing backflow of the coal feeding air into the coal feeder or other equipment. The shape and position of the guide plate 8 help optimize the transport of pulverized coal within the inclined coal pipe 201, reduce pulverized coal deposition within the pipe, and ensure that pulverized coal can smoothly enter the furnace 1.

[0039] In some embodiments, the projection of the axis of the inclined coal pipe 201 is located within the projection of the guide plate 8 in a projection plane orthogonal to the axis of the inclined coal pipe 201.

[0040] The projection of the baffle 8 covers the projection of the inclined coal pipe 201 axis, which helps to accelerate the coal feeding air, enabling it to carry pulverized coal more effectively. The accelerated coal feeding air can generate a stronger airflow, which helps to entrain pulverized coal, allowing it to enter the furnace 1 directly, rather than depositing in the coal drop pipe 2. The design of the baffle 8 prevents the coal feeding air from backflowing into the vertical coal feed pipe, ensuring that the airflow flows in the designed direction.

[0041] In some embodiments, a first control valve 9 is provided on the first branch pipe 302, a second control valve 10 is provided on the second branch pipe 303, and a third control valve 11 is provided on the third branch pipe 304.

[0042] By installing control valves on each branch pipe, the airflow in each branch pipe can be independently adjusted to adapt to different boiler operating conditions and combustion requirements. The control valves precisely control the airflow in each branch pipe, ensuring more rational airflow distribution and improving combustion efficiency. Through the adjustment of the control valves, the system can more flexibly respond to different load demands and combustion conditions, improving the boiler's operating efficiency and adaptability.

[0043] In the description of this invention, 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," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0044] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0045] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0046] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0047] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0048] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A high-efficiency air intake system for preventing backflow in the coal chute of a circulating fluidized bed boiler, characterized in that, include: Furnace (1); A coal chuting pipe (2) includes an inclined coal chuting pipe (201) and a vertical coal chuting pipe (202). The first end of the inclined coal chuting pipe (201) is connected to the furnace (1), and the second end of the inclined coal chuting pipe (201) gradually slopes upwards in a direction away from the furnace (1). The vertical coal chuting pipe (202) is vertically positioned above and connected to the inclined coal chuting pipe (201). The air inlet pipe (3) includes a main pipe (301), a first branch pipe (302), a second branch pipe (303), and a third branch pipe (304). The first branch pipe (302) is connected to the second end of the inclined coal pipe (201) and conveys the air for spreading coal along the axial direction of the inclined coal pipe (201). The second branch pipe (303) is located upstream of the vertical coal pipe (202) and is connected to the inclined coal pipe (201). The second branch pipe (303) is used to convey the air for spreading coal along the axial direction of the inclined coal pipe (201) and toward the inner wall surface of the inclined coal pipe (201). The third branch pipe (304) is located downstream of the vertical coal pipe (202) and is connected to the inclined coal pipe (201). The third branch pipe (304) is used to convey the air for spreading coal toward the first end of the inclined coal pipe (201).

2. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 1, characterized in that, It also includes a first fan, a second fan, an air preheater, a first air duct (4) and a second air duct (5). The first fan is connected to the inlet of the air preheater, and the outlet of the air preheater is connected to the inlet pipe (3) through the first air duct (4) to deliver hot primary air into the main pipe (301). The second fan is connected to the main pipe (301) through the second air duct (5) to deliver room temperature air into the main pipe (301).

3. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 2, characterized in that, The difference between the air pressure of the second blower and the air pressure of the hot secondary air in the furnace (1) is greater than or equal to 3 kPa.

4. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 2, characterized in that, The first air duct (4) is provided with a first flow regulating valve (6), and the second air duct (5) is provided with a second flow regulating valve (7).

5. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 1, characterized in that, The diameter of the inclined coal pipe (201) is D1, and the diameter of the third branch pipe (304) is D2, where 1 / 3≤D2 / D1≤1.

6. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 1, characterized in that, It also includes a guide plate (8), which is disposed inside the inclined coal pipe (201) and is set at an angle to the axis of the inclined coal pipe (201).

7. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 6, characterized in that, The inclined coal pipe (201) has a coal drop port (2011) communicating with the vertical coal pipe (202) on its pipe wall. The guide plate (8) is located at the coal drop port (2011). In the projection plane orthogonal to the axis of the vertical coal pipe (202), at least a portion of the projection of the guide plate (8) is located within the projection of the coal drop port (2011).

8. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 7, characterized in that, The first end of the guide plate (8) is located upstream of the coal drop outlet (2011) and connected to the top wall of the inclined coal pipe (201). The second end of the guide plate (8) gradually slopes downward along the direction from the second end of the inclined coal pipe (201) toward the first end of the inclined coal pipe (201).

9. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 8, characterized in that, In the projection plane orthogonal to the axis of the inclined coal pipe (201), the projection of the axis of the inclined coal pipe (201) is located within the projection of the guide plate (8).

10. The anti-backflow high-efficiency air intake system for coal chutes in circulating fluidized bed boilers according to claim 1, characterized in that, The first branch pipe (302) is provided with a first control valve (9), the second branch pipe (303) is provided with a second control valve (10), and the third branch pipe (304) is provided with a third control valve (11).

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