Multi-channel material circulating system of circulating fluidized bed boiler and circulating material adjusting method

Abstract

The invention discloses a multi-channel material circulating system of a circulating fluidized bed boiler and a circulating material adjusting method, and belongs to the technical field of circulating fluidized bed boilers. The multi-channel material circulating system comprises a separator, a separated material branch channel and a material returning channel; a discharge port at the bottom of the separator is connected with more than two independent separated material branch channels, an outlet of each separated material branch channel is connected with an independent material returning channel to form a material circulating channel, and each material circulating channel is provided with an air chamber for independently adjusting air volume; and an outlet of the material returning channel is connected with the hearth water cooling wall. By controlling stop or start of fluidization air of the air chambers in one or more material circulation channels, the amount of external circulation materials participating in material external circulation during operation of the boiler is controlled, and rapid and efficient adjustment of the circulation materials can be achieved.

Description

Technical Field

[0001] This invention belongs to the technical field of circulating fluidized bed boilers, and in particular, it relates to a multi-channel material circulation system and a method for regulating circulating materials in a circulating fluidized bed boiler. Background Technology

[0002] In recent years, new energy sources such as wind power and solar power have been developed vigorously in the power generation sector. However, wind power and solar power are highly random and volatile, requiring thermal power units in the power grid to improve their peak-shaving capacity in order to better absorb new energy power.

[0003] Fluidized bed units in thermal power plants have seen significant development in recent years due to their strong fuel adaptability, high load regulation ratio, and low pollutant generation. In a circulating fluidized bed boiler, flue gas carrying a large amount of high-temperature material enters the separator at the furnace outlet. The separator then sends the separated material through the separator riser to the return feeder, which in turn sends the recycled material back into the boiler. Thus, the boiler furnace, separator, riser, and return feeder form the external circulation system of the circulating fluidized bed boiler. During boiler operation, a large amount of recycled material participates in the boiler's material circulation.

[0004] Material circulation in circulating fluidized bed (CFB) boilers plays a crucial role in unit operation. A large amount of high-temperature circulating material participates in the external circulation of the CFB boiler, significantly impacting heat transfer, heat distribution, pollutant generation, bed temperature control, and load-bearing capacity. The quantity of circulating material has a significant influence on CFB boiler operation, affecting the operating bed temperature, NOx generation, and in-furnace desulfurization efficiency. It also relates to the boiler's heat transfer and load-bearing capacity, significantly impacting its operational safety, environmental friendliness, and economic efficiency.

[0005] When the unit needs to rapidly change load, the amount of circulating material participating in the external circulation needs to be quickly adjusted to regulate the boiler bed temperature, heat exchange, and steam temperature changes. When the unit is at low load, the amount of circulating material participating in the external circulation needs to be reduced to increase the bed temperature, improve boiler combustion stability, and enhance the unit's desulfurization efficiency.

[0006] However, currently, for circulating fluidized bed units, under specific loads, the amount of circulating ash involved in material circulation can only be adjusted slightly and slowly by adjusting the primary air volume. There is no effective way to quickly and over a large area control the amount of circulating material involved in the external circulation of materials in a circulating fluidized bed boiler.

[0007] In existing technology, the separator, riser, and return feeder of a circulating fluidized bed boiler are a one-to-one single series system. If any device in the riser or return feeder becomes blocked, the circulation system cannot continue to operate, causing a serious imbalance in the amount of circulating material in the furnace area, affecting the safe and stable operation of the boiler, requiring emergency shutdown, and resulting in a significant increase in operating costs.

[0008] Therefore, there is an urgent need for a system and method that can quickly and efficiently adjust the amount of material circulating in the external circulation of a circulating fluidized bed boiler, while also improving the operational safety of the material circulation system of the circulating fluidized bed boiler. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a multi-channel material circulation system and a method for regulating circulating material in a circulating fluidized bed boiler, so as to achieve the purpose of quickly and efficiently regulating the amount of material participating in the external circulation of the circulating fluidized bed boiler.

[0010] To solve the above technical problems, according to one aspect of the present invention, a multi-channel material circulation system for a circulating fluidized bed boiler is provided, comprising a separator, separate material branch channels, and a return material channel; the discharge port at the bottom of the separator is connected to two or more independent separate material branch channels, the outlet of each separate material branch channel is connected to an independent return material channel to form a material circulation channel, and each material circulation channel is provided with a wind chamber for individually adjusting the air volume; the outlet of the return material channel is connected to the furnace water-cooled wall.

[0011] Furthermore, the bottom of the separator is connected to a separator riser, which forms the branch channel for the separated material. The lower part of the separator riser has two or more independent outlets. The outlets of the separator riser are connected to a return feeder, which forms the return channel.

[0012] Furthermore, it includes multiple return feeders, each with an independent return channel. The separator riser outlet is connected to the inlet of each return feeder, and each return feeder has an air chamber connected to its bottom.

[0013] Furthermore, a return feeder uses an isolation device to form two or more independent return channels; each separator riser outlet is connected to a return channel, and each return channel has an air chamber at its bottom.

[0014] Furthermore, the separator riser includes a separator riser main pipe, an expanded diameter section, and separator riser branch pipes; the top of the separator riser main pipe is connected to the separator, and the bottom of the separator riser main pipe is expanded to form an expanded diameter section. An isolation component is provided inside the expanded diameter section to divide the expanded diameter section into two or more independent channels. The outlet of each channel is connected to an independent separator riser branch pipe, and the outlet of the separator riser branch pipe is connected to a return feeder.

[0015] Furthermore, the height of the separator riser branch pipe is twice the height of the separator riser main pipe, and the diameter of the separator riser branch pipe is equal to the diameter of the separator riser main pipe.

[0016] Furthermore, an air duct is provided at the bottom of the air chamber, and an air duct valve is provided on the air duct.

[0017] According to another aspect of the present invention, a method for regulating circulating material in a circulating fluidized bed boiler is provided. The method employs the multi-channel material circulation system of the circulating fluidized bed boiler described above. By controlling the stopping or starting of the fluidizing air in the air chamber of one or more material circulation channels, the amount of external circulating material participating in the external material circulation during boiler operation is controlled.

[0018] Furthermore, when the unit needs to reduce the amount of circulating material, the fluidizing air in the air chamber of one or more material circulation channels is stopped, and the circulating material is stored in the corresponding separation material branch channel and return material channel.

[0019] Furthermore, when the unit needs to adjust the amount of circulating material, the fluidizing air in the air chamber of one or more material circulation channels that are in a stopped state is restarted, and the circulating material stored in the separation material branch channel and return material channel is returned to the furnace to participate in the boiler circulation.

[0020] Compared with the prior art, the beneficial technical effects that the present invention can achieve include: 1. The circulating material volume of the boiler can be adjusted. When the unit needs to reduce the circulating material volume, one or more separate material branch channels and return material channels can be shut down, and the circulating material can be stored in the separate material branch channels and return material channels. When the unit needs to increase the circulating material volume, one or more separate material branch channels and return material channels can be activated, and the circulating material stored therein can be returned to the furnace to participate in the boiler circulation. This can realize the rapid storage and discharge of circulating material.

[0021] 2. By rapidly storing and discharging circulating materials, the concentration of circulating materials in the furnace is changed, which enables rapid increases and decreases in heat exchange within the boiler furnace, rapid changes in output, and improves the boiler's load regulation rate.

[0022] 3. By adjusting the amount of circulating material in the furnace, the combustion and heat release ratio between the dense phase and dilute phase zones can be changed, increasing the bed temperature of the boiler at low loads, enhancing its stable combustion capability at low loads, increasing the flue gas temperature at the boiler furnace outlet, and improving denitrification efficiency at low loads. It also effectively controls the bed temperature at high loads, improving the safety and environmental performance of the boiler during high-load operation.

[0023] 4. The storage and discharge of circulating materials in the system are controlled by adjusting the air volume of the return feeder. No valves are needed in the entire material flow loop, which can reduce flow resistance and prevent valve failure and leakage, thus preventing accidents.

[0024] 5. The storage and discharge speed of circulating materials is very fast, with a storage rate of 15~100t / min, which can meet the requirements of rapid load change of boiler.

[0025] 6. Direct storage and discharge of high-temperature circulating materials, with high storage and discharge efficiency, safety and efficiency, and good boiler regulation performance.

[0026] 7. When one of the material separation branch channels or return feeder channels becomes blocked, the other material separation branch channels and return feeder channels corresponding to the separator can continue to operate, ensuring the smooth circulation of materials and reducing the number of abnormal boiler shutdowns.

[0027] 8. The system is simple, easy to operate, and highly reliable. Attached Figure Description

[0028] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention.

[0029] Figure 1 This is a schematic diagram of a two-branch material circulation system disclosed in an embodiment of the present invention; Figure 2 yes Figure 1 Rear view; Figure 3 yes Figure 1 Side view; Figure 4 This is another partial structural schematic diagram of the two-branch material circulation system disclosed in an embodiment of the present invention; Figure 5 This is a schematic diagram of a three-branch material circulation system disclosed in an embodiment of the present invention.

[0030] 1-Separator, 2-Separator riser main pipe, 3-Separator riser branch pipe, 4-Return feeder, 5-Return feeder inlet, 6-Return feeder outlet pipe, 7-Furnace water-cooled wall, 8-Air chamber, 9-Air duct, 10-Air duct valve, 11-Separator inlet, 12-Expanded diameter section, 13-Separator cone section, 14-Separator flue gas outlet. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the present invention will be further described clearly and completely below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0032] In this invention, "two or more" or "multiple" used to define the quantity means an integer quantity of two or more.

[0033] This invention provides a multi-channel material circulation system for a circulating fluidized bed boiler, comprising a separator 1, separate material branch channels, and a return material channel. The outlet at the bottom of the separator 1 connects to two or more independent separate material branch channels. The outlet of each separate material branch channel is connected to an independent return material channel to form a material circulation channel. The return material channel is independent from inlet to outlet, with no branching or merging. Each material circulation channel is equipped with an air chamber 8, allowing for individual adjustment of the fluidizing air entering each circulation channel. The outlet of the return material channel is connected to the furnace water-cooled wall 7, and the circulating material enters the furnace from the return material channel. An air duct 9 is located at the bottom of the air chamber 8, and an air duct valve 10 is installed on the air duct 9.

[0034] According to the above implementation method, during the operation of the circulating fluidized bed boiler, the circulating material separated by separator 1 enters the separated material branch channel, and then enters the independent return material channel from the outlet of the separated material branch channel, and finally enters the furnace from the return material channel. The air chamber 8 provides sufficient fluidizing air to bubble and fluidize the circulating material in the return material channel, allowing it to flow.

[0035] By controlling the stopping or starting of the fluidizing air in the air chamber 8 of one or more material circulation channels, the amount of externally circulated material participating in the external material circulation during boiler operation can be controlled. When the unit needs to reduce the amount of circulating material, the fluidizing air in the air chamber 8 of one or more material circulation channels is stopped, and the circulating material is stored in the corresponding separation material branch channel and return material channel. When the unit needs to increase the amount of circulating material, the fluidizing air in the air chamber of one or more material circulation channels that was stopped is restarted, and the circulating material stored in the separation material branch channel and return material channel is returned to the furnace to participate in the boiler circulation.

[0036] In a preferred embodiment, the bottom of the separator 1 is connected to a separator riser, and an isolation component is provided inside the separator riser to divide it into two or more material separation branch channels, and the lower part of the separator riser has two or more independent outlets; the outlet of the separator riser is connected to a return feeder 4, and the return feeder 4 forms the return channel, dividing the circulating material separated by the separator 1 into two or more parts that enter the return feeder 4.

[0037] In a relatively specific implementation, the separator riser includes a separator riser main pipe 2 and a separator riser branch pipe 3; the top of the separator riser main pipe 2 is connected to the separator 1, the bottom of the separator riser main pipe 2 is connected to two or more independent separator riser branch pipes 3, and the outlet of the separator riser branch pipe 3 is connected to the return inlet 5 of the return material device 4.

[0038] For example, such as Figures 1-3As shown, the lower part of the separator riser is bifurcated in an inverted "Y" shape to form two separator riser branch pipes 3. The separator riser branch pipes 3 are connected to the return feeder 4, which divides the circulating material separated by the separator 1 into two parts and enters the return feeder 4.

[0039] Alternatively, by way of example, the lower part of the separator riser is branched into multiple branches to form multiple separator riser branches 3. The separator riser branches 3 are connected to the return feeder 4, and the circulating material separated by the separator 1 is divided into multiple parts and enters the return feeder 4.

[0040] In another relatively specific embodiment, the separator riser includes a separator riser main pipe 2, an expanded diameter section 12, and a separator riser branch pipe 3; the top of the separator riser main pipe 2 is connected to the separator 1, and the bottom of the separator riser main pipe 2 is expanded to form an expanded diameter section 12. An isolation component is provided inside the expanded diameter section 12 to divide the expanded diameter section 12 into two or more independent channels. The outlet of each channel is connected to an independent separator riser branch pipe 3, and the outlet of the separator riser branch pipe 3 is connected to the return inlet 5 of the return material device 4.

[0041] For example, such as Figures 1-3 As shown, the separator riser is first enlarged and then bifurcated in an inverted "Y" shape to form two separator riser branch pipes 3. The separator riser branch pipes 3 are connected to the return feeder 4, which divides the circulating material separated by the separator 1 into two parts and enters the return feeder 4.

[0042] Alternatively, by way of example, the separator riser is first reduced in diameter and then branched into multiple branches to form multiple separator riser branches 3. The separator riser branches 3 are connected to the return feeder 4, and the circulating material separated by the separator 1 is divided into multiple parts and enters the return feeder 4.

[0043] In the above embodiments, the top of the separator 1 is provided with a separator inlet 11 and a separator flue gas outlet 14, the lower part of the separator 1 is provided with a separator cone 13, and the separator riser main pipe 2 is connected to the separator cone 13.

[0044] In another embodiment, such as Figure 4 , Figure 5 As shown, two or three separator riser branch pipes 3 can be directly connected to the bottom of the separator vertebral segment 13.

[0045] Preferably, the height of the separator riser branch pipe 3 is twice the height of the separator riser main pipe 2, and the diameter of the separator riser branch pipe 3 is equal to the diameter of the separator riser main pipe 2. The longer separator riser branch pipe 3 has a larger volume, which can store and release more circulating ash, and has a more significant effect on improving the variable load rate and stable combustion capability.

[0046] This implementation provides two different types of return channels.

[0047] In one embodiment, a plurality of return feeders 4 are included, each return feeder 4 being a single-channel return feeder with an independent return channel, the outlet of the separator riser branch pipe 3 being connected to the inlet of each return feeder 4, and the bottom of each return feeder 4 being connected to an air chamber 8.

[0048] In another embodiment, the return feeder 4 uses an isolation device to form two or more independent return channels; the outlet of each separator riser branch pipe 3 is connected to the return channel, and an air chamber 8 is provided at the bottom of each return channel.

[0049] To enable those skilled in the art to more easily understand the present invention, the technical solution claimed by the present invention will be further clearly and completely described below through a relatively specific embodiment.

[0050] In this embodiment, a separator cone segment 13 is provided at the lower part of the separator 1, and the separator riser main pipe 2 is connected to the separator cone segment 13. The lower part of the separator main pipe 2 is enlarged to form an enlarged section 12, which is connected to two separator riser branch pipes 3. Each separator riser branch pipe 3 is connected to a return material inlet 5. Each return material 4 has an independent return material channel. The return material outlet pipe 6 is connected to the furnace water-cooled wall 7. The lower part of the return material 4 is an air chamber 8, and an air duct valve 10 is provided on the air duct 9 of the air chamber 8.

[0051] During the operation of the circulating fluidized bed boiler, the circulating material separated by separator 1 enters the separator riser main pipe 2, then splits into two paths into the separator riser branch pipes 3, and then enters an independent return channel through the return feeder inlet 5, and finally enters the furnace from the independent return feeder outlet pipe 6. The air chamber 8 provides sufficient fluidizing air to cause the circulating material inside the return feeder to bubble and fluidize, thus flowing.

[0052] For a 300MW circulating fluidized bed unit, three sets of cyclone separators and return feeder systems are installed. During normal operation, the total bed material volume is approximately 120m³. 3 The amount of recycled material participating in the external circulation is approximately 60m³. 3 The return channel of each separator riser branch pipe 3 and the corresponding return feeder 4 has a volume of 15m³. 3 Each return channel and separator branch riser can store 1 / 4 of the circulating material. When one branch of each of the three cyclone separators and return feeder systems is out of service, 3 / 4 of the circulating material can be stored, thus reducing the amount of circulating material by 3 / 4.

[0053] When the boiler needs to rapidly reduce its load, the amount of circulating material participating in the external circulation needs to be reduced. This can be achieved by stopping the airflow in the lower air chamber 8 of one return feeder, thus stopping the operation of that material circulation channel. This stops the flow of circulating material, and within 20 seconds, 15m³ of material can be removed from the external circulation. 3 The circulating material is stored in the return channel of the return feeder 4 and the branch pipe 3 of the separator riser. The circulating material separated by the separator 1 is returned to the furnace through another branch for circulation, ensuring the normal operation of the separator and the uniform distribution of circulating material in the furnace.

[0054] Reducing the amount of material involved in the external circulation can decrease the heat transfer coefficient of the boiler water-cooled wall and the furnace screen-type heating surface by 30% to 60%, thereby rapidly reducing the boiler load and increasing the boiler load reduction rate by more than 50%, exceeding 4% Pe / min.

[0055] Specifically, based on the load reduction rate and magnitude of the load reduction command, the number of separator and return feeder branches that need to be shut down is determined. The higher the load reduction rate and the greater the load reduction magnitude, the more branches need to be shut down, and vice versa.

[0056] When the boiler needs to rapidly increase its load, the amount of circulating material participating in the external circulation needs to be increased. This can be achieved by restarting a stopped material circulation channel, allowing the stored circulating material to participate in the furnace's external circulation. Specifically, this involves opening the air duct valve 10 on the air duct 9, allowing fluidizing air to quickly enter the air chamber 8 and the return feeder 4, causing the circulating material stored inside the return feeder 4 to bubble and fluidize. In this way, the circulating material stored in the return feeder channel and the separator riser branch pipe 3 begins bubbling and fluidizing again, flowing back into the furnace.

[0057] Each return channel and separator branch riser can store twice the existing amount of circulating material, thus doubling the circulating material volume. For a 300MW circulating fluidized bed unit, three sets of cyclone separators and return systems are installed; when all branches of the three cyclone separators and return systems are running, all the originally stored circulating material can participate in the circulation, thereby increasing the circulating material volume by three times.

[0058] Reducing the amount of material involved in the external circulation can increase the heat transfer coefficient of the boiler water-cooled wall and the furnace screen-type heating surface by 30% to 60%, thereby rapidly increasing the boiler load and increasing the boiler load rate by more than 50%, exceeding 4% Pe / min.

[0059] Specifically, based on the load increase rate and magnitude of the load increase command, the number of separator and return feeder branches that need to be activated is determined. The higher the load increase rate and magnitude, the more branches need to be activated, and vice versa.

[0060] When the boiler needs to operate at low load, the amount of circulating material participating in the external circulation needs to be reduced. The operation of that material circulation channel can be stopped by stopping the airflow in the lower air chamber 8 of one return feeder. This stops the flow of circulating material, storing it in the return channel of the return feeder 4 and the branch pipe 3 of the separator riser. When the return channel and the riser pipe 3 of the separator are full of circulating material, the circulating material separated by the separator 1 returns to the furnace through another branch for circulation. Each return channel and the riser pipe 3 of the separator can store 1 / 4 of the circulating material, thus reducing the amount of circulating material by 1 / 4. For a 300MW circulating fluidized bed unit, three sets of cyclone separators and return feeder systems are installed; when one branch of each of the three cyclone separators and return feeder systems is shut down, 3 / 4 of the circulating material can be stored, thus reducing the amount of circulating material by 3 / 4.

[0061] Reducing the amount of material involved in the external circulation decreases the heat carried into the boiler's water-cooled walls and furnace-mounted heat exchange surfaces. More heat remains in the dense phase zone of the furnace, increasing the bed temperature in the dense phase zone by 50°C to 100°C at low loads. This makes boiler operation safer at low loads and improves in-furnace desulfurization efficiency. It can further reduce the boiler's low-load stable combustion load by 5 percentage points, reaching below 20%.

[0062] When the boiler needs to operate at high loads, the amount of circulating material participating in the external circulation needs to be increased. This can be achieved by restarting a stopped material circulation channel, allowing the stored circulating material to participate in the external circulation of the furnace. Specifically, the air duct valve 10 on the air duct 9 is opened, allowing fluidizing air to quickly enter the air chamber 8 and the return feeder 4, bubbling and fluidizing the circulating material stored inside the return feeder 4. In this way, the circulating material stored in the return channel and the separator riser branch pipe 3 begins bubbling and fluidizing again, flowing back into the furnace. Each return channel and separator branch riser pipe 3 can store twice the existing amount of circulating material, thus doubling the circulating material volume. For a 300MW circulating fluidized bed unit, three sets of cyclone separators and return feeder systems are installed; when all branches of the three cyclone separator and return feeder systems are running, all the originally stored circulating material can participate in the circulation, thus increasing the amount of circulating material participating in the circulation by three times.

[0063] The increased amount of material involved in the external circulation increases the amount of heat carried into the boiler water-cooled walls and the furnace screen-type heating surfaces. More heat is carried from the dense phase zone of the furnace to the upper water-cooled walls and screen-type heating surfaces, which reduces the bed temperature in the dense phase zone by 50°C to 100°C under high load. This ensures that the boiler bed temperature does not exceed the limit under high load, making operation safer and the desulfurization efficiency in the furnace higher.

[0064] Specifically, based on the dispatch load command, the number of separator and return feeder branches that need to be shut down or started is determined. The lower the load, the more branches need to be shut down; the higher the load, the more branches need to be started.

[0065] The scope of protection claimed by this invention is not limited to the specific embodiments described above. For those skilled in the art, this invention can have various modifications and alterations. Any modifications, improvements, and equivalent substitutions made within the concept and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A multi-channel material circulation system for a circulating fluidized bed boiler, characterized in that: It includes a separator (1), a material separation branch channel and a return channel; the discharge port at the bottom of the separator (1) is connected to two or more independent material separation branch channels, and the outlet of each material separation branch channel is connected to an independent return channel to form a material circulation channel. Each material circulation channel is equipped with a wind chamber (8) for individually adjusting the air volume; the outlet of the return channel is connected to the furnace water-cooled wall (7).

2. The multi-channel material circulation system for a circulating fluidized bed boiler according to claim 1, characterized in that: The bottom of the separator (1) is connected to the separator riser, which forms the separation material branch channel. The lower part of the separator riser has two or more independent outlets. The outlet of the separator riser is connected to the return feeder (4), which forms the return material channel.

3. The multi-channel material circulation system for a circulating fluidized bed boiler according to claim 2, characterized in that: It includes multiple return feeders (4), each return feeder (4) has an independent return channel, the outlet of the separator riser is connected to the inlet of each return feeder (4), and the bottom of each return feeder (4) is connected to an air chamber (8).

4. The multi-channel material circulation system for a circulating fluidized bed boiler according to claim 2, characterized in that: A return feeder (4) uses an isolation device to form two or more independent return channels; the outlet of each separator riser is connected to the return channel, and the bottom of each return channel is equipped with an air chamber (8).

5. The multi-channel material circulation system for a circulating fluidized bed boiler according to claim 3 or 4, characterized in that: The separator riser includes a separator riser main pipe (2), an expansion section (12), and a separator riser branch pipe (3). The top of the separator riser main pipe (2) is connected to the separator (1). The bottom of the separator riser main pipe (2) is expanded to form an expansion section (12). An isolation component is installed inside the expansion section (12) to divide the expansion section (12) into two or more independent channels. The outlet of each channel is connected to an independent separator riser branch pipe (3). The outlet of the separator riser branch pipe (3) is connected to a return feeder (4).

6. The multi-channel material circulation system for a circulating fluidized bed boiler according to claim 5, characterized in that: The height of the separator riser branch pipe (3) is twice the height of the separator riser main pipe (2), and the diameter of the separator riser branch pipe (3) is equal to the diameter of the separator riser main pipe (2).

7. The multi-channel material circulation system for a circulating fluidized bed boiler according to claim 1 or 6, characterized in that: The bottom of the air chamber (8) is provided with an air duct (9), and an air duct valve (10) is provided on the air duct (9).

8. A method for regulating circulating materials in a circulating fluidized bed boiler, characterized in that: The circulating fluidized bed boiler multi-channel material circulation system according to any one of claims 1-7 controls the amount of external circulating material participating in the external material circulation during boiler operation by controlling the stop or start of the fluidizing air in the air chamber (8) of one or more material circulation channels.

9. The circulating material adjustment method for a circulating fluidized bed boiler according to claim 8, characterized in that: When the unit needs to reduce the amount of circulating material, stop the fluidizing air in the air chamber (8) of one or more material circulation channels and store the circulating material in the corresponding separation material branch channel and return channel.

10. The circulating material adjustment method for a circulating fluidized bed boiler according to claim 8, characterized in that: When the unit needs to adjust the amount of circulating material, the fluidizing air in the air chamber (8) of one or more material circulation channels that are in a stopped state is restarted, and the circulating material stored in the separation material branch channel and return material channel is returned to the furnace to participate in the boiler circulation.

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