Circulating fluidized bed reactor and control method thereof, combustion system

Abstract

The present invention relates to a circulating fluidized bed reactor comprising two reaction chambers, a separator and a return device, which are in communication with each other to form a circulation loop, wherein: the reactant inlet of the reaction chamber is arranged at the lower part of the reaction chamber, and is adapted to provide a reactant material gas stream into the reaction chamber to sweep the inner surface of the bottom of the reaction chamber. The present invention also relates to a combustion system comprising a furnace, a direct firing pulverizing device and the above-mentioned circulating fluidized bed reactor, wherein: the reactant inlet of the reaction chamber is in communication with the direct firing pulverizing device; the circulating fluidized bed reactor is a preheating burner, and the upper outlet of the separator is in communication with the furnace of the above-mentioned circulating fluidized bed reactor. The present invention also relates to a method for controlling the above-mentioned circulating fluidized bed reactor.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of fluidization technology, and more particularly to a circulating fluidized bed reactor, a method for controlling a circulating fluidized bed reactor, and a combustion system including a circulating fluidized bed reactor. Background Technology

[0002] Fluidized bed reactors have wide applications in various fields. When used as the main reactor in combustion and gasification, the fuel particle size is typically greater than 2 mm. However, when used as a fuel pre-processor, especially a preheating burner, the fuel particle size is usually less than 0.5 mm, requiring a medium-storage or direct-fired pulverizing system. Large-capacity industrial boilers (e.g., 130 t / h and above) and power plant boilers typically use direct-fired pulverizing systems. These systems are simpler, require fewer devices, have shorter pipelines, and lower investment costs. Compared to medium-storage pulverizing systems, powdered fuel has no intermediate residence time, and the gas-powder temperature is lower, reducing the risk of explosion. Furthermore, the pulverizing system consumes less electricity for coal grinding. Therefore, matching preheating burners with direct-fired pulverizing systems is essential for the application of preheating burners in large-capacity boilers.

[0003] In existing technologies, the air supply system of preheating burners is divided into fluidizing air and pulverizing air. The fluidizing air fan supplies fluidizing air from the bottom air cap, and its main function is to establish the fluidization state of the material. The pulverizing air fan supplies pulverizing air from the bottom of the reaction chamber, and its main function is to transport powdered fuel. Both provide oxidant for the chemical reaction of fuel in the preheating burner.

[0004] One of the main problems encountered when matching a preheating burner with a direct-fired pulverizing system is that the direct-fired pulverizing system is only equipped with a pulverizing fan and does not have a fluidizing fan. This requires additional equipment investment during the matching process, reducing economic efficiency. Furthermore, compared to existing direct-fired pulverizing systems that only have a pulverizing fan, the current preheating burner's air supply is divided into two streams. While ensuring the total air volume supplied to the preheating burner remains constant, a portion is diverted to the fluidizing fan, resulting in a lower pulverizing air volume. This leads to a reduced air-to-powder mass ratio, deviating from the stable operating range of the existing pulverizing system, thus affecting economic efficiency and safety.

[0005] Furthermore, existing technologies struggle to achieve rapid start-up and shutdown of the preheating unit for powdered fuel. When the preheating unit shuts down, i.e., when no pulverized air is being supplied, material within the preheating chamber accumulates at the junction of the conical bottom and the pulverized fuel conveying pipeline. Because the accumulated material is at a high temperature, the combustibles may undergo pyrolysis, releasing sticky substances such as tar, accelerating blockage at the junction and preventing the pulverized fuel from entering the preheating chamber. The only solution is to clean and restart the unit, increasing operational complexity and maintenance time, and reducing operational safety.

[0006] Furthermore, in existing technologies, a large reaction dead zone is prone to exist at the bottom of the preheating chamber. Since the coal conveying gas enters the preheating chamber through the bottom conical flare structure, and the gas velocity decreases, especially when the operating load is reduced, a reaction dead zone forms near the conical wall. As the preheating unit operates for longer periods, the heat released from the pyrolysis and gasification of the stagnant high-temperature fuel gradually accumulates within this dead zone, potentially causing problems such as localized coking, and ultimately preventing the preheating unit from operating normally and safely. Summary of the Invention

[0007] The present invention addresses at least one aspect of the problems in the prior art.

[0008] According to one aspect of the present invention, a circulating fluidized bed reactor is provided, comprising two interconnected reaction chambers, a separator, and a return feeder, forming a circulation loop.

[0009] in:

[0010] The reactant inlet of the reaction chamber is located at the bottom of the reaction chamber, which is suitable for providing a flow of reactant material to purge the inner surface of the bottom of the reaction chamber.

[0011] According to another aspect of the embodiments of the present invention, a combustion system is also provided, including a furnace; a direct-fired pulverizing device; and the aforementioned circulating fluidized bed reactor, wherein: the reaction chamber is a preheating chamber, and the reactant inlet of the reaction chamber is connected to the direct-fired pulverizing device; the circulating fluidized bed reactor is a preheating burner and the upper outlet of the separator is connected to the furnace.

[0012] According to another aspect of the present invention, a method for controlling the above-mentioned circulating fluidized bed reactor is provided, comprising the step of: ensuring that the flow velocity of the powdered reactant gas entering the reaction chamber from the reactant inlet is always higher than 10 m / s. Attached Figure Description

[0013] The above and other aspects and features of the present invention will become clear from the following description of embodiments taken in conjunction with the accompanying drawings, wherein:

[0014] Figure 1 This is a schematic diagram of the structure of a circulating fluidized bed reactor according to an exemplary embodiment of the present invention;

[0015] Figure 2A and Figure 2B for Figure 1 A schematic diagram of the circulating fluidized bed reactor in the image shows the relevant angle and height parameters;

[0016] Figure 3 This is a schematic diagram of the structure of a circulating fluidized bed reactor according to another exemplary embodiment of the present invention;

[0017] Figures 4A-4E It shows Figure 1 Different embodiments of reactant inlet settings for a medium-circulating fluidized bed reactor;

[0018] Figures 5A-5E Different embodiments of the reactant inlet configuration of a circulating fluidized bed reactor according to another embodiment of the present invention are shown. Detailed Implementation

[0019] The following description of embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be construed as a limitation thereof.

[0020] The circulating fluidized bed reactor of the present invention will now be described by way of example with reference to the accompanying drawings.

[0021] This invention proposes a circulating fluidized bed reactor, comprising two interconnected reaction chambers, a separator, and a return feeder, forming a circulation loop. The reactant inlet of each reaction chamber is located at its lower part, suitable for providing a gas flow of reactant material to purge the inner surface of the bottom of the reaction chamber. The purging effect of the reactant material gas flow reduces the problem of localized coking caused by the accumulation of reactant material at the bottom of the reaction chamber.

[0022] In one embodiment of the present invention, reference is made to... Figures 1-4E The bottom of the reaction chamber of the circulating fluidized bed reactor is an ellipsoidal / spherical arc-shaped section. The inlet of the reactant is configured such that the inlet direction of the powdered fuel or powdered material is obliquely downward, which is suitable for providing the reactant gas flow into the arc-shaped section in an obliquely downward manner.

[0023] In one embodiment of the present invention, such as Figures 1-2B As shown, the reactant inlet is located in the region below the reduced cross-section of the reaction chamber, and in the region above the ellipsoidal / spherical cross-section.

[0024] The powdered material can be pulverized coal or biomass powder, or low-volatile fuels such as semi-coke fine powder.

[0025] A specific application of the above technical solution is as a circulating fluidized bed gasification device for powdered fuel. For example... Figure 1 As shown, the fluidized bed reactor includes a reaction chamber 1 (which can be a riser pipe as one form of reaction chamber), a separator, and a return feeder 3. The upper part of the reaction chamber 1 is connected to the separator 2, the separator 2 is connected to the return feeder 3, and the outlet of the return feeder 3 is connected to the conical structure of the reaction chamber 1. The above structures form a circulation structure. The outlet of the return feeder 3 is connected to the conical section in the lower part of the reaction chamber 1, and the gasification products flow out from the top outlet pipe of the separator 2.

[0026] Near the reaction chamber 1, the powder conveying pipeline splits into two branches, which are tangentially connected to the semi-ellipsoidal structure at an angle downwards. The powdered air carries the powdered fuel into the reaction chamber 1 through the powder conveying pipeline, and passes through the reaction chamber 1, separator 2, and return feeder 3 several times in a circulation loop. The gasification products flow out from the separator outlet.

[0027] for Figure 1 In one embodiment of the circulating fluidized bed gasification apparatus shown, powdered fuel is gasified in a fluidized bed reactor at a high temperature (700-1200°C), and the gasification products, including coal gas and fly ash, flow out from the separator outlet.

[0028] exist Figures 1-2B In the illustrated embodiment, the powder conveying velocity in the main powder conveying pipeline and the two branch powder conveying pipelines is always higher than 10 m / s. Furthermore, the upward flow velocity of the powdered fuel carried by the powdered gas flow within the semi-ellipsoidal body is 0.5 to 30 m / s, and more specifically 15 m / s.

[0029] exist Figure 1 and Figure 2A In the illustrated embodiment, the powder conveying pipeline splits into two smaller diameter powder conveying pipelines near the reaction chamber 1, and the two powder conveying pipelines are arranged symmetrically. The invention is not limited to this; it can also consist of more powder conveying pipelines. These additional powder conveying pipelines can be arranged at equal intervals along the circumference. More specifically, the two symmetrical powder conveying duct branches near the reaction device can be replaced by four or six symmetrical branches. Increasing the number of tangentially entering powder feeding pipes connected to the bottom of the reaction device is beneficial for further improving the flow uniformity of materials at the bottom of the reaction zone, enhancing reaction uniformity, and avoiding localized high-temperature zones. Although not shown, only one powder conveying pipeline may be provided; all of these are within the scope of protection of this invention.

[0030] More specifically, see, for example Figures 4A-4E The image shows a top view along axis AA, which exemplarily illustrates the arrangement of the powder conveying duct branches. Figure 4A In the middle, two powder conveying duct branches are arranged tangentially and 180 degrees apart in the same spiral direction, while two other powder conveying duct branches are arranged radially opposite each other. Figure 4B In this configuration, one powder conveying pipe branch is arranged tangentially, while the other is arranged radially. Figure 4C In the middle, two powder conveying pipe branches are arranged opposite each other. Figure 4D In the middle, two powder conveying pipe branches are arranged tangentially and 180 degrees apart in the same spiral direction. Figure 4E In the middle, the four powder conveying pipe branches are arranged tangentially and separated by 90 degrees in the same direction of rotation.

[0031] As those skilled in the art will understand, there are other arrangements, which will not be listed here.

[0032] The following reference Figures 1-3 Specifically, the shape of the bottom of the reaction chamber in this invention is described. In an embodiment of this invention, the bottom is a concave arc-shaped portion. This arc-shaped portion can be an ellipsoidal arc-shaped portion or a spherical arc-shaped portion, more specifically, it can be a 1 / 2 or 1 / 4 ellipsoidal structure or a 1 / 2 or 1 / 4 spherical structure.

[0033] The following is a reference to the appendix. Figures 1-3 Specifically, this invention describes the downward-sloping arrangement of the powder conveying pipeline. For example... Figures 1-3 As shown, the powder conveying pipeline enters the semi-ellipsoid at a tangential downward angle. The lower plane of the powder conveying pipeline coincides with the tangent line on the inner surface of the semi-ellipsoid at the connection point between the semi-ellipsoid and the conical segment. That is, the lower edge of the channel space of the powder conveying pipeline coincides with the tangent line of the inner arc surface at the upper edge of the arcuate portion of the semi-ellipsoid. However, the above is a very specific arrangement, and the present invention is not limited to it. The arrangement of the powder conveying pipeline is sufficient as long as it is "set to be inclined downward to be suitable for providing the gas flow of reactant material into the arcuate portion in an inclined downward manner." It can be "the powder conveying pipeline is set to connect with the upper edge of the arcuate portion and inclined downward to be suitable for providing the gas flow of reactant material into the arcuate portion in an inclined downward manner." Furthermore, "the axis of the powder conveying pipeline is set parallel to the tangent line of the inner arc surface at the upper edge of the arcuate portion."

[0034] The following is a reference to the appendix. Figures 1-3 This example illustrates the cone angle of the conical section and the angle of the powder conveying pipeline. In one embodiment of the invention, such as... Figure 2A , 2B As shown, 60° < α < 90°: the angle between the oblique conical surface of the cone and the horizontal plane is 60° to 90°, where α is the angle between the oblique conical surface of the cone and the horizontal plane. In one embodiment of the invention, α > β: the angle between the oblique conical surface of the cone and the horizontal plane is greater than the angle between the tangent line on the semi-ellipsoid and the horizontal plane at the connection point between the semi-ellipsoid and the cone segment, where β is the angle between the tangent line on the semi-ellipsoid and the horizontal plane at the connection point between the semi-ellipsoid and the cone segment. In one embodiment of the invention, both α and β are acute angles greater than 60 degrees.

[0035] The cross-sectional shape of the reaction chamber is described in detail below. Figure 1 and Figure 2A In the illustrated embodiment, the upper part of the reaction chamber 1 is cylindrical, the middle and lower parts taper downwards into a conical segment, and the bottom is semi-ellipsoidal. That is, the reaction chamber 1 includes a cylindrical segment, a conical segment, and an arc-shaped portion connected sequentially in the vertical direction. The upper edge of the larger diameter of the conical segment connects to the cylindrical segment, and the lower edge of the smaller diameter of the conical segment connects to the arc-shaped portion. However, the present invention is not limited thereto. See also... Figure 3 Reaction chamber 1, except for the bottom, is a conical section, such as... Figure 3 As shown, it has been cancelled. Figure 1 and Figure 2AThe upper part of the reaction device is cylindrical, while the overall upper structure is conical and the bottom is semi-ellipsoidal. This ensures that there is always a velocity difference along the reaction zone, which is beneficial for the internal circulation of materials and improves the reaction intensity.

[0036] Furthermore, although not shown, the reaction chamber 1 may also be entirely cylindrical or cylindrical except for the bottom, which is also within the scope of protection of this invention.

[0037] The following example illustrates the vertical dimensions of the reaction chamber.

[0038] In one embodiment of the present invention, such as Figure 2A As shown, the total height of reaction chamber 1 is h, the height of the cylindrical section is h1, the height of the conical section is h2, and the height of the arc-shaped part is h3. h = h1 + h2 + h3, meaning that the starting point of the downward narrowing in the lower part of reaction chamber 1 is 1 / 3 to 1 / 2 of the total height of the reaction chamber from the bottom.

[0039] In one embodiment of the present invention, the total height of the reaction chamber is h, the height of the arc-shaped portion is h3, and... This indicates that the variable structure position in the lower part of reaction chamber 1, towards the semi-ellipsoidal bottom, is 1 / 100 to 1 / 50 of the total height of the reaction chamber.

[0040] exist Figures 1-3 In the illustrated embodiment, the bottom of the reaction chamber or riser is arc-shaped, but the invention is not limited thereto. For example, as Figures 5A-5E As shown, the bottom can also be a circular horizontal bottom, with the reactant inlet or powder conveying duct branch of the reaction chamber arranged parallel to the horizontal bottom to provide airflow of reactant materials into the reaction chamber.

[0041] See Figures 5A-5E Its powder conveying duct branches can also have similar characteristics. Figures 4A-4E The arrangement method will not be described in detail here.

[0042] In one embodiment of the invention, the upper plane of the conical structure coincides with the lower plane of the cylindrical structure, and in the vertical projection, the projection of the lower part of the cone is located at the center of the projection of the upper part of the cylinder. In a further embodiment, the upper plane of the semi-ellipsoidal structure coincides with the lower plane of the conical structure, and in the vertical projection, the projection of the bottom of the semi-ellipsoid is located at the center of the projection of the lower part of the cone.

[0043] In this invention, by using the above-mentioned inclined downward reaction material inlet, the bottom of the reaction chamber 1 can be free of wind chambers or wind caps.

[0044] In this invention, the powdered fuel has a larger specific surface area, resulting in a more complete reaction and facilitating the reduction in the size of the fluidized bed reactor.

[0045] In this invention, the powder conveying airflow serves both to fluidize the material and to transport the fuel powder, simplifying the process and improving the ease of operation of the equipment.

[0046] In this invention, symmetrically arranged powder conveying pipes enter the semi-ellipsoidal bottom of the reaction zone tangentially, wherein the symmetrical arrangement and tangential entry of the fuel-carrying gas flow can minimize the generation of dead zones at the bottom of the reaction zone.

[0047] In this invention, the constricted structure in the lower middle part of the reaction zone or reaction chamber enables the fluidization velocity in the local area to reach a high flow rate, which enhances the uniformity of material flow, avoids local high temperature zones, and improves the intensity of chemical reaction.

[0048] Although not shown, in embodiments of the present invention, the angle formed between the axis of the powder conveying pipe and the horizontal plane can be changed or adjusted; or the axis of the powder conveying pipe can be set to form an angle with the vertical section so that the gas flow of reactant entering the arc section from the powder conveying pipe has a circumferential swirling direction, and further, the angle formed with the vertical section can also be adjusted.

[0049] As will be understood, in this invention, unless otherwise specified, the numerical range includes endpoint values, and in addition to the values ​​already listed, the numerical range may also include intermediate values, 1 / 3 values, or 2 / 3 values.

[0050] The fluidized bed reactor described above can also be a component of a combustion system, for example... Figure 1 and Figure 3 The reaction products formed by the structure shown can be injected into the boiler furnace as fuel.

[0051] Based on the above, the present invention proposes the following technical solution:

[0052] 1. A circulating fluidized bed reactor, comprising two interconnected reaction chambers, a separator, and a return feeder, forming a circulating loop.

[0053] in:

[0054] The reactant inlet of the reaction chamber is located at the bottom of the reaction chamber, which is suitable for providing a flow of reactant material to purge the inner surface of the bottom of the reaction chamber.

[0055] 2. The circulating fluidized bed reactor according to claim 1, wherein:

[0056] The bottom of the reaction chamber includes a recessed arc-shaped portion, and the reactant inlet of the reaction chamber is configured to be inclined downward so as to provide a flow of reactant material into the arc-shaped portion in an inclined downward manner.

[0057] 3. The circulating fluidized bed reactor according to claim 2, wherein:

[0058] The reactant inlet is configured to connect with the upper edge of the arc-shaped portion and be inclined downward, thereby being suitable for providing a flow of reactant into the arc-shaped portion in an inclined downward manner.

[0059] 4. The circulating fluidized bed reactor according to 3, wherein:

[0060] The axis of the reactant inlet is parallel to the tangent of the inner arc surface at the upper edge of the arc-shaped part.

[0061] 5. The circulating fluidized bed reactor according to 4, wherein:

[0062] The lower edge of the channel space of the reactant inlet is set to coincide with the tangent of the inner arc surface of the arc-shaped part at the upper edge.

[0063] 6. The circulating fluidized bed reactor according to claim 2, wherein:

[0064] The axis of the reactant inlet forms a first angle with the horizontal plane, which is greater than 60 degrees and less than 90 degrees.

[0065] 7. The circulating fluidized bed reactor according to claim 2, wherein:

[0066] The arc-shaped portion is either an ellipsoidal arc-shaped portion or a spherical arc-shaped portion.

[0067] 8. The circulating fluidized bed reactor according to 7, wherein:

[0068] The arc-shaped portion is a 1 / 2 or 1 / 4 ellipsoidal structure or a 1 / 2 or 1 / 4 spherical structure.

[0069] 9. The circulating fluidized bed reactor according to claim 2, wherein:

[0070] The reaction chamber includes a cylindrical section, a conical section, and an arc-shaped portion connected in sequence in the vertical direction. The upper edge of the larger diameter of the conical section is connected to the cylindrical section, and the lower edge of the smaller diameter of the conical section is connected to the arc-shaped portion. The solid outlet of the separator is connected to the conical section.

[0071] 10. The circulating fluidized bed reactor according to claim 9, wherein:

[0072] The upper end of the cone segment forms a second angle with the horizontal plane, the second angle being greater than the first angle; and / or

[0073] The total height of the reaction chamber is h, the height of the cylindrical section is h1, the height of the conical section is h2, and the height of the arc-shaped section is h3.

[0074] 11. The circulating fluidized bed reactor according to claim 2, wherein:

[0075] The reaction chamber includes a cylindrical section and the arc-shaped portion connected sequentially in a vertical direction, the top of the cylindrical section defining the top of the reaction chamber; or

[0076] The reaction chamber includes a conical segment and an arcuate portion connected sequentially in the vertical direction, with the top of the conical segment defining the top of the reaction chamber.

[0077] 12. The circulating fluidized bed reactor according to claim 2, wherein:

[0078] The axis of the reaction chamber passes through the center of the vertical projection of the arcuate portion.

[0079] 13. The circulating fluidized bed reactor according to claim 2, wherein:

[0080] The total height of the reaction chamber is h, and the height of the arc-shaped part is h³, and

[0081] 14. The circulating fluidized bed reactor according to claim 1, wherein:

[0082] The bottom of the reaction chamber is a circular horizontal bottom, and the reactant inlet of the reaction chamber is set parallel to the horizontal bottom to provide a gas flow of reactant material into the reaction chamber.

[0083] 15. The circulating fluidized bed reactor according to claim 1, wherein:

[0084] The fluidized bed reactor includes multiple reactant inlets, as shown in the top view:

[0085] The plurality of reactant inlets are arranged at equal intervals in the circumferential direction; and / or

[0086] At least one reactant inlet is arranged tangentially along the bottom of the reaction chamber; and / or

[0087] At least one reactant inlet is arranged radially along the bottom of the reaction chamber.

[0088] 16. The circulating fluidized bed reactor according to any one of 1-15, wherein:

[0089] The reactant inlet of the reaction chamber is suitable for connection with a direct-blown pulverizing device.

[0090] 17. A combustion system, comprising:

[0091] Furnace;

[0092] Direct-blown pulverizing device;

[0093] The circulating fluidized bed reactor according to any one of 1-15,

[0094] in:

[0095] The reaction chamber is a preheating chamber, and the reactant inlet of the reaction chamber is connected to the direct-blown pulverizing device;

[0096] The circulating fluidized bed reactor is a preheating burner and the upper outlet of the separator is connected to the furnace.

[0097] 18. A method for controlling a fluidized bed reactor according to any one of 1-16, comprising the steps of:

[0098] This ensures that the flow velocity of the powdered reactant gas entering the reaction chamber from the reactant inlet is always higher than 10 m / s.

[0099] 19. The method according to 18, comprising the steps of:

[0100] This ensures that the upward flow velocity of the reactant gas stream carrying the powdered reactant entering the reaction chamber is in the range of 0.5-30 m / s, and further, in the range of 10-20 m / s.

[0101] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that variations and combinations of elements may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A circulating fluidized bed reactor, comprising two interconnected reaction chambers, a separator, and a return feeder, forming a circulating loop. in: The reactant inlet of the reaction chamber is located at the bottom of the reaction chamber and is adapted to provide a flow of reactant material to purge the inner surface of the bottom of the reaction chamber. The flow of reactant material includes powdered reactant material. The bottom of the reaction chamber includes a recessed arc-shaped portion, and the reactant inlet of the reaction chamber is configured to be inclined downward so as to provide a flow of reactant material into the arc-shaped portion in an inclined downward manner; The reactant inlet is configured to connect with the upper edge of the arc-shaped portion and be inclined downward, thereby being suitable for providing a flow of reactant into the arc-shaped portion in an inclined downward manner; The axis of the reactant inlet is set parallel to the tangent of the inner arc surface at the upper edge of the arc-shaped part.

2. The circulating fluidized bed reactor according to claim 1, wherein: The lower edge of the channel space of the reactant inlet is set to coincide with the tangent of the inner arc surface of the arc-shaped part at the upper edge.

3. The circulating fluidized bed reactor according to claim 1, wherein: The axis of the reactant inlet forms a first angle with the horizontal plane, which is greater than 60 degrees and less than 90 degrees.

4. The circulating fluidized bed reactor according to claim 1, wherein: The arc-shaped portion is either an ellipsoidal arc-shaped portion or a spherical arc-shaped portion.

5. The circulating fluidized bed reactor according to claim 4, wherein: The arc-shaped portion is a 1 / 2 or 1 / 4 ellipsoidal structure or a 1 / 2 or 1 / 4 spherical structure.

6. The circulating fluidized bed reactor according to claim 1, wherein: The reaction chamber includes a cylindrical section, a conical section, and an arc-shaped portion connected sequentially in the vertical direction. The upper edge of the larger diameter of the conical section is connected to the cylindrical section, and the lower edge of the smaller diameter of the conical section is connected to the arc-shaped portion. The solid outlet of the return feeder is connected to the conical section.

7. The circulating fluidized bed reactor according to claim 6, wherein: The upper end of the cone segment forms a second angle with the horizontal plane, the axis of the reactant inlet forms a first angle with the horizontal plane, and the second angle is greater than the first angle; and / or The total height of the reaction chamber is h, the height of the cylindrical section is h1, the height of the conical section is h2, and the height of the arc-shaped section is h3. h = h1 + h2 + h3.

8. The circulating fluidized bed reactor according to claim 1, wherein: The reaction chamber includes a cylindrical section and the arc-shaped portion connected sequentially in a vertical direction, the top of the cylindrical section defining the top of the reaction chamber; or The reaction chamber includes a conical segment and an arcuate portion connected sequentially in the vertical direction, with the top of the conical segment defining the top of the reaction chamber.

9. The circulating fluidized bed reactor according to claim 1, wherein: The axis of the reaction chamber passes through the center of the vertical projection of the arcuate portion.

10. The circulating fluidized bed reactor according to claim 1, wherein: The total height of the reaction chamber is h, and the height of the arc-shaped part is h³, and .

11. The circulating fluidized bed reactor according to claim 1, wherein: The circulating fluidized bed reactor includes multiple reactant inlets, as shown in the top view: The plurality of reactant inlets are arranged at equal intervals in the circumferential direction; and / or At least one reactant inlet is arranged tangentially along the bottom of the reaction chamber; and / or At least one reactant inlet is arranged radially along the bottom of the reaction chamber.

12. The circulating fluidized bed reactor according to any one of claims 1-11, wherein: The reactant inlet of the reaction chamber is suitable for connection with a direct-blown pulverizing device.

13. A combustion system, comprising: Furnace; Direct-blown pulverizing device; And a circulating fluidized bed reactor according to any one of claims 1-11; in: The reaction chamber is a preheating chamber, and the reactant inlet of the reaction chamber is connected to the direct-blown pulverizing device; The circulating fluidized bed reactor is a preheating burner, and the upper outlet of the separator is connected to the furnace.

14. A method for controlling a circulating fluidized bed reactor according to any one of claims 1-12, comprising the steps of: This ensures that the flow velocity of the powdered reactant gas entering the reaction chamber from the reactant inlet is always higher than 10 m / s.

15. The method of claim 14, comprising the steps of: This ensures that the upward flow velocity of the reactant gas entering the reaction chamber, carrying the powdered reactant, is within the range of 0.5-30 m / s.

16. The method of claim 15, comprising the steps of: This ensures that the upward flow velocity of the reactant gas entering the reaction chamber, carrying the powdered reactant, is within the range of 10-20 m / s.

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