Supercritical and ultra-supercritical cfbs with quick load change, control method

Abstract

The present application relates to the technical field of CFB boiler, in particular to supercritical and ultra-supercritical CFB boiler capable of quick load change, regulation and control method, the boiler comprises: a hearth device, including a hearth body and an ignition combustion assembly; an external circulation loop, including a cyclone separator and an integrated storage and return device, the integrated storage and return device includes a direct return mechanism and a storage and return mechanism; the direct return mechanism includes a first descending channel, a first ascending channel and a return channel, the storage and return mechanism includes a second descending channel, a second ascending channel, a storage structure and a return channel; a tail wall structure, including a recovery flue, a plurality of heat exchange devices are arranged in the recovery flue. By improving the structure of the boiler, the concentration of ash material in the circulating channel of the boiler is regulated and controlled, the load in the furnace is adjusted in time, so that the quick load change of the CFB boiler is realized, and the supercritical and ultra-supercritical main steam parameter adjustment can be realized.

Description

Technical Field

[0001] This invention relates to the field of CFB (Circulating Fluidized Bed Boiler) technology, specifically to supercritical and ultra-supercritical CFB boilers capable of rapid load changes and their control methods. Background Technology

[0002] Thermal power generating units need to have excellent deep peak-shaving capabilities to absorb renewable energy indicators and help build a new power system with renewable energy as the main body.

[0003] Based on this, thermal power units will shift from power generation-oriented to regulation-oriented power sources. This requires coal-fired units to adapt to the new situation—by absorbing new energy sources and ensuring the stability and security of the power grid supply through deep peak shaving and flexible operation. In some provinces with prominent new energy development, the demand for deep peak shaving of thermal power units is even more urgent, requiring existing units to be retrofitted to have the capability for deep peak shaving operation. Especially after the recent introduction of the new generation of coal-fired power indicators, the requirements for deep and rapid peak shaving of coal-fired power units have been further increased, and daytime start-up and shutdown requirements have also been introduced. This requires boilers to take corresponding measures to ensure the safety, flexibility, and economy of the units during deep and rapid peak shaving.

[0004] Currently, commonly used deep peak-shaving technologies for thermal power units mainly achieve dynamic grid balance through deep load changes of 20% to 50% of the rated load, thermoelectric decoupling, or unit start-up and shutdown. However, peak-shaving using start-up and shutdown methods for thermal power units is relatively expensive, and frequent start-up and shutdown can also affect the lifespan of the units. Therefore, deep load change technology has become the main approach for thermal power units to participate in flexible peak-shaving. At present, coal-fired CFB (combustion-free) units can typically only achieve a peak-shaving depth of 30%, while advanced levels or certain modifications can reach about 20%. The implementation plan for the new generation of coal-fired power construction has put forward higher requirements for the peak-shaving depth and ramp-up rate of coal-fired power units. However, CFB boilers, due to their unique gas-solid flow and combustion methods, have greater thermal inertia and more heat storage, which puts them at a certain disadvantage in terms of load changes.

[0005] Unlike pulverized coal boilers, CFB boilers contain a large amount of circulating ash, which continuously circulates in the furnace-separator-return feeder-furnace main loop, significantly impacting the flow pattern, combustion, and heat transfer within the furnace. This abundant circulating ash stores most of the heat released from the fuel and circulates within the furnace, ensuring stable and uniform combustion temperature in the CFB boiler. However, it also introduces significant flow inertia into the system, resulting in a slower load change rate for the CFB boiler. The magnitude of this flow inertia ultimately reflects the rate of change of the effective circulating ash volume within the furnace; the faster the effective circulating ash volume changes, the smaller the flow inertia. Therefore, rapidly changing the effective circulating ash volume within the furnace during load changes becomes one of the key issues that needs to be addressed to improve the load change rate of the CFB boiler.

[0006] Studies have shown that particle concentration is a crucial factor affecting heat exchange between the furnace and heating surfaces in CFB boilers, with a positive correlation between heat transfer coefficient and particle concentration. In the dilute phase region, both particle concentration and heat transfer coefficient increase with increasing circulating ash content. However, in the dense phase region, once the particle concentration reaches the critical concentration for the bubbling bed, both particle concentration and heat transfer coefficient no longer increase with increasing circulating ash content. CFB boilers inherently contain a large amount of circulating ash. If the circulating ash content remains unchanged during load changes, it will introduce significant heat transfer inertia into the system, resulting in a slow load change rate for the CFB boiler. Therefore, rapidly changing the effective circulating ash content within the furnace during load changes is a critical issue that needs to be addressed to improve the load change rate of CFB boilers. Thus, a more reasonable technical solution is needed to solve the existing technical problems. Summary of the Invention

[0007] To overcome at least one of the aforementioned defects, this invention proposes a supercritical and ultra-supercritical CFB boiler with rapid load change capability and a control method. By adjusting and improving the storage and return structure, the particulate matter in the combustion process can be flexibly controlled, thereby adjusting the combustion situation in the furnace and timely and rapidly controlling the load of circulating materials in the circulating furnace, thus realizing rapid load change of the CFB boiler to meet the needs of deep peak shaving.

[0008] To achieve the above objectives, the boiler disclosed in this invention can adopt the following technical solution:

[0009] Supercritical and ultra-supercritical CFB boilers capable of rapid load changes include:

[0010] The furnace assembly includes the furnace body and an ignition and combustion assembly that cooperates with the dense phase zone of the furnace body.

[0011] The external circulation loop includes a cyclone separator connected to the furnace body. The lower part of the cyclone separator is connected to an integrated material storage and return device. The integrated material storage and return device includes a direct return mechanism and a material storage and return mechanism. The direct return mechanism includes a first descending channel, a first ascending channel, and a return channel. The material storage and return mechanism includes a second descending channel, a second ascending channel, a material storage structure, and a return channel. Both the return channel and the material return channel are connected to the furnace body. The material return channel is controlled by a control valve.

[0012] The tail wall structure includes a recovery flue that is connected to the furnace body and receives the flue gas inside the furnace body. Several heat exchange devices are installed in the recovery flue.

[0013] The aforementioned CFB boiler utilizes an integrated material storage and return device to regulate the return of circulating materials within the furnace, effectively controlling the ash concentration and enabling rapid adjustment of the furnace load. When the integrated material storage and return device reduces the amount of material returned to the furnace body, the ash concentration decreases, which facilitates reducing flow inertia and accelerating the reduction of the furnace's heat transfer coefficient, resulting in a rapid response of steam parameters. Conversely, when the integrated material storage and return device increases the amount of material returned to the furnace body, the ash concentration increases, which facilitates a rapid increase in the amount of circulating ash within the furnace, thereby increasing the material concentration and ultimately improving the furnace's heat transfer coefficient and accelerating the improvement of steam parameters.

[0014] Furthermore, the direct return material mechanism is used to send solid particulate matter such as ash in the circulating furnace channel back to the furnace body for further reaction without storage. Its structure is not limited to a single one. Here, optimization is carried out and one feasible option is proposed: the inlet of the first descending channel is connected to a cyclone separator, and the outlet of the first descending channel is connected to the first ascending channel to transport materials and form an upward bend connection port. An upper partition wall is provided at the upward bend connection port; the first ascending channel is connected to the return material channel to transport materials, and a lower partition wall is provided at the connection point. The upper edge of the lower partition wall is higher than the lower edge of the upper partition wall; a first air distribution plate is also provided in the first descending channel and the first ascending channel. The first air distribution plate is used to adjust the feeding air pressure in the first descending channel and the first ascending channel. When the above scheme is adopted, the first descending channel is connected to a cyclone separator through a riser to receive particulate matter such as ash. At the upper bend connection, an isolation structure for the material is formed by the upper partition wall. The ash reaching the upper bend connection can form a certain accumulation and cover the channel surface of the upper bend connection, thereby maintaining the airtightness of the channel and the sealing of the furnace circulation channel. The height of the lower partition wall is higher than that of the upper partition wall, which helps to increase the accumulation height of the ash. When the ash enters the return channel from the ascending channel, it needs to cross a step, which helps to prevent air leakage at the upper bend connection. The first air distribution plate is used to blow the ash in the upper bend connection to the return channel. The ash entering the return channel slides into the furnace body along the return channel under the action of wind pressure and gravity.

[0015] Furthermore, the material storage and return mechanism is used to store some ash and other particulate matter, and can adjust the speed at which the ash is returned to the furnace body, thereby flexibly and quickly adjusting the load inside the furnace body. The material storage and return mechanism can adopt various schemes, and its structure is not limited to a single one. Here, optimization is performed, and one feasible option is proposed: the inlet of the second descending channel is connected to a cyclone separator, and the outlet of the second descending channel is connected to the second ascending channel to transport materials and form an upward bend connection port, where an upper partition wall is provided; the second ascending channel is connected to the material storage structure to transport materials, and a lower partition wall is provided at the connection point, with the upper edge of the lower partition wall higher than the lower edge of the upper partition wall; a second air distribution plate is also provided in the second descending channel and the second ascending channel, and the second air distribution plate is used to adjust the feeding air pressure in the second descending channel and the second ascending channel. When the above scheme is adopted, the functions of the upper partition wall and the lower partition wall are the same as those in the direct return material mechanism, both used to maintain the airtightness of the channel; when the second air distribution plate ventilates, the ash material at the upper bend connecting port is blown into the storage structure for storage; when the return material channel is opened, the ash material in the storage structure can enter the furnace body through the return material channel.

[0016] Furthermore, the coordination between the cyclone separator and the direct material return mechanism and the storage material return mechanism can adopt various schemes to form multiple coordination mechanisms, and its structure is not limited to a single one. Here, we optimize and propose one feasible option: The number of cyclone separators is several. When the number of cyclone separators is one, the cyclone separator is simultaneously connected to and coordinated with both the direct material return mechanism and the storage material return mechanism. When the number of cyclone separators is greater than one, the cyclone separator is individually connected to and coordinated with either the direct material return mechanism or the storage material return mechanism, or the cyclone separator is simultaneously connected to and coordinated with both the direct material return mechanism and the storage material return mechanism. When adopting the above scheme, the coordination structure between the cyclone separator and the direct material return mechanism and the storage material return mechanism can be set according to the actual equipment layout requirements.

[0017] Furthermore, in some solutions, to simplify the equipment structure, the direct material return mechanism and the storage material return mechanism can share some structural components. One feasible option is proposed here: the first and second descending channels are the same channel. When using the above solution, after obtaining the ash material through this channel, it can be blown in different directions to deliver the ash material to the corresponding direct material return mechanism or storage material return mechanism.

[0018] Furthermore, the storage structure, used to store ash materials for easy adjustment of the circulation channel load, is not limited to a single structure. Here, we propose an optimized and feasible option: the storage structure includes a storage silo with a third air distribution plate at its bottom for adjusting the feeding air pressure within the silo. The second descending channel and the second ascending channel are both located on the side of the storage silo and used to convey materials into it. The return channel is connected to the storage silo and used to transport the materials from the silo to the furnace body. With this scheme, multiple return channels can be provided, guiding the ash materials to the furnace body under the influence of air pressure and gravity.

[0019] Furthermore, after the boiler has been operating for a certain period of time, when the total amount of ash in the circulation channel reaches a certain level and exceeds the demand for load adjustment, the excess ash needs to be discharged. A feasible option is proposed here: an ash discharge channel is installed at the storage silo, and an ash discharge control valve is installed at the ash discharge channel. When adopting the above solution, the ash discharge control valve can be a gate valve.

[0020] Furthermore, the ignition and combustion assembly, in conjunction with the furnace body, ignites the material. Its structure is not uniquely limited; optimization is proposed here, and one feasible option is suggested: the ignition and combustion assembly includes an ignition burner, an ignition channel, and a water-cooled air chamber connected in sequence, with the water-cooled air chamber connected to a port at the lower part of the furnace body; the ignition and combustion assembly also includes a coal feeding device and a secondary air duct connected to the lower part of the furnace body; the furnace body also contains an in-furnace heating structure. When adopting the above scheme, the coal feeding device can use multiple coal feeding ports to add material into the furnace body from multiple directions.

[0021] Furthermore, the tail-end wall-mounted mechanism is used to recover and utilize heat from the flue gas. Its structure is not limited to a single design; here, optimization is proposed, and one feasible option is suggested: the top of the cyclone separator is equipped with an outlet flue, which connects to the recovery flue and transports high-temperature flue gas. The recovery flue includes a superheating and reheating section, an economizing section, a denitrification section, and an air preheating section. An ash hopper is located at the end of the recovery flue. In this scheme, a superheater and a reheater are installed in the superheating and reheating section; an economizer is installed in the economizing section; the denitrification section can be connected to a denitrification mechanism to purify the flue gas; an air preheater is installed in the air preheating section; and the ash hopper at the end is used to collect ash materials mixed in the flue gas.

[0022] The above content discloses the structure of supercritical and ultra-supercritical CFB boilers, and the present invention also provides a method for controlling the boiler.

[0023] Control methods for supercritical and ultra-supercritical CFB boilers capable of rapid load changes include:

[0024] Start the boiler to allow the materials to burn in the furnace to produce flue gas and ash.

[0025] The cyclone separator sends the flue gas to the tail wall structure for heat recovery and centrally transports the ash material to the integrated storage and return device below.

[0026] When it is necessary to control and reduce the effective circulating ash in the furnace, close the control valve of the storage and return mechanism, and at the same time, select to open or close the return air of the direct return mechanism according to the set requirements, so as to guide all or part of the ash to the storage and return mechanism for storage.

[0027] When it is necessary to control the effective circulating ash amount in the furnace, the fluidizing air of the direct return mechanism and the storage return mechanism are opened at the same time, and the control valve of the storage return mechanism is opened to guide the ash to the furnace body.

[0028] When the load inside the furnace reaches the specified level and runs stably, the ash discharge operation is carried out through the material storage and return mechanism to provide storage space.

[0029] The aforementioned control method utilizes the structural characteristics of the integrated ash storage device to control the amount of ash material entering the boiler circulation channel during boiler operation, thereby adjusting the boiler load. Since it is equipped with both a direct return mechanism and a storage return mechanism, it can regulate the ash material and quickly complete the concentration adjustment of ash material in the circulation channel, thereby completing the boiler load adjustment.

[0030] Compared with the prior art, some of the beneficial effects of the technical solution disclosed in this invention include:

[0031] This invention improves the boiler structure to control the concentration of ash materials in the boiler circulation channel, facilitating timely adjustment of the load in the furnace and enabling rapid load changes in the CFB boiler. It also allows for the adjustment of main steam parameters in both supercritical and ultra-supercritical environments. Attached Figure Description

[0032] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of the overall structure of a CFB boiler.

[0034] Figure 2 This is a top view of the integrated material storage and return device of the CFB boiler.

[0035] Figure 3 This is a side view of an integrated material storage and return device.

[0036] Figure 4 This is a schematic diagram showing the flow direction of ash material at the integrated material storage and return device.

[0037] Figure 5 for Figure 4 Schematic diagram of cross-section at point AA.

[0038] Figure 6 for Figure 4 Schematic diagram of cross-section at point BB.

[0039] In the above attached figures, the meanings of each label are as follows:

[0040] 1. Ignition burner; 2. Ignition channel; 3. Water-cooled air chamber; 4. Coal feeding device; 5. Secondary air duct; 6. Furnace body; 7. In-furnace heating structure; 8. Separator inlet flue; 9. Outlet flue; 10. Cyclone separator; 11. Riser; 12. First descending channel; 13. First ascending channel; 14. Second ascending channel; 15. Return material channel; 16. Recovery flue; 17. Superheating and reheating section; 18. Economizer section; 19. Denitrification section; 20. Air preheating section; 21. Ash hopper; 22. Upper partition wall; 23. Lower partition wall; 24. First air distribution plate; 25. Second air distribution plate; 26. Return material channel; 2601. Return material gate valve; 27. Ash discharge channel; 2701. Ash discharge gate valve; 28. Third air distribution plate; 29. ​​Storage bin. Detailed Implementation

[0041] The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this embodiment.

[0042] In response to the increasing performance requirements of existing CFB boilers and the greater demand for variable loads, which traditional CFB boilers cannot effectively meet, the following embodiments are adjusted to overcome the deficiencies of the existing technology.

[0043] Example 1

[0044] like Figure 1 As shown, this embodiment provides a supercritical and ultra-supercritical CFB boiler capable of rapid load change, comprising:

[0045] The furnace assembly includes a furnace body 6 and an ignition and combustion assembly that cooperates with the dense phase zone of the furnace body 6.

[0046] The external circulation loop includes a cyclone separator 10 connected to the furnace body 6. The lower part of the cyclone separator 10 is connected to an integrated storage and return device. The integrated storage and return device includes a direct return mechanism and a storage and return mechanism. The direct return mechanism includes a first descending channel 12, a first ascending channel 13, and a return channel 15. The storage and return mechanism includes a second descending channel, a second ascending channel 14, a storage structure, and a return channel 26. Both the return channel 15 and the return channel 26 are connected to the furnace body 6. The return channel 26 is controlled by a control valve.

[0047] The tail wall structure includes a recovery flue 16 that is connected to the furnace body 6 and receives the flue gas inside the furnace body 6. Several heat exchange devices are installed in the recovery flue 16.

[0048] Preferably, the control valve in this embodiment is a gate valve. Specifically, a return gate valve 2601 is provided on the return channel 26.

[0049] The CFB boiler disclosed in this embodiment uses an integrated material storage and return device to regulate the return of circulating materials within the furnace, effectively controlling the ash concentration and enabling rapid adjustment of the furnace load. When the integrated material storage and return device reduces the amount of material returned to the furnace body 6, the ash concentration in the furnace decreases. This facilitates reducing flow inertia and accelerating the reduction of the heat transfer coefficient within the furnace, achieving a rapid response in steam parameters. Conversely, when the integrated material storage and return device increases the amount of material returned to the furnace body 6, the ash concentration in the furnace increases. This facilitates a rapid increase in the amount of circulating ash within the furnace, increasing the material concentration and thus improving the heat transfer coefficient and accelerating the improvement of steam parameters.

[0050] like Figures 2-6 As shown, the direct return material mechanism is used to send solid particulate matter such as ash in the circulating furnace channel back to the furnace body 6 for further reaction without storage. Its structure is not limited to a single one. This embodiment optimizes and adopts one feasible option: the inlet of the first descending channel 12 is connected to the cyclone separator 10, and the outlet of the first descending channel 12 is connected to the first ascending channel 13 to transport materials and form an upward bend connection port. An upper partition wall 22 is provided at the upward bend connection port; the first ascending channel 13 is connected to the return material channel 15 to transport materials. A lower partition wall 23 is provided at the connection point, and the upper edge of the lower partition wall 23 is higher than the lower edge of the upper partition wall 22; a first air distribution plate 24 is also provided in the first descending channel 12 and the first ascending channel 13. The first air distribution plate 24 is used to adjust the feeding air pressure in the first descending channel 12 and the first ascending channel 13. When the above scheme is adopted, the first descending channel 12 is connected to the cyclone separator 10 through the riser 11 to receive particulate matter such as ash. At the upper bend connection, the upper partition wall 22 forms a material isolation structure. The ash reaching the upper bend connection can form a certain accumulation and cover the channel surface of the upper bend connection, thereby maintaining the airtightness of the channel and the sealing of the furnace circulation channel. The lower partition wall 23 is higher than the upper partition wall 22, which helps to increase the accumulation height of the ash. When the ash enters the return channel 15 from the ascending channel, it needs to cross a step, which helps to avoid air leakage at the upper bend connection. The first air distribution plate 24 is used to blow the ash in the upper bend connection to the return channel 15. The ash entering the return channel 15 slides into the furnace body 6 along the return channel 15 under the action of wind pressure and gravity.

[0051] Preferably, the height of the ramp in this embodiment is set to 100mm to 500mm.

[0052] like Figures 2-6As shown, the material storage and return mechanism is used to store some ash and other particulate matter. It can adjust the speed at which the material returns to the furnace body 6, thereby flexibly and quickly adjusting the load inside the furnace body 6. The material storage and return mechanism can adopt various schemes, and its structure is not limited to one. This embodiment optimizes and adopts one feasible option: the inlet of the second descending channel is connected to the cyclone separator 10, and the outlet of the second descending channel is connected to the second ascending channel 14 to transport materials and form an upper bend connection port. An upper partition wall 22 is provided at the upper bend connection port; the second ascending channel 14 is connected to the material storage structure to transport materials, and a lower partition wall 23 is provided at the connection point. The upper edge of the lower partition wall 23 is higher than the lower edge of the upper partition wall 22; a second air distribution plate 25 is also provided in the second descending channel and the second ascending channel 14. The second air distribution plate 25 is used to adjust the feeding air pressure in the second descending channel and the second ascending channel 14. When the above scheme is adopted, the functions of the upper partition wall 22 and the lower partition wall 23 are the same as those in the direct return material mechanism, both used to maintain the airtightness of the channel; when the second air distribution plate 25 ventilates, the ash material at the upper bend connection is blown into the storage structure for storage; when the return material channel 26 is opened, the ash material in the storage structure can enter the furnace body 6 through the return material channel 26.

[0053] like Figure 2 As shown, the cyclone separator 10 can be coupled with the direct material return mechanism and the storage material return mechanism in various ways, forming multiple coupling mechanisms. Its structure is not uniquely limited. This embodiment optimizes and adopts one feasible option: the number of cyclone separators 10 is several. When the number of cyclone separators 10 is one, the cyclone separator 10 is simultaneously connected to both the direct material return mechanism and the storage material return mechanism. When the number of cyclone separators 10 is greater than one, the cyclone separator 10 is individually connected to either the direct material return mechanism or the storage material return mechanism, or the cyclone separator is simultaneously connected to both. When adopting the above scheme, the connection and coupling structure of the cyclone separator 10 with the direct material return mechanism and the storage material return mechanism can be set according to the actual equipment layout requirements.

[0054] like Figures 2-6 As shown, in some schemes, to simplify the equipment structure, the direct material return mechanism and the storage material return mechanism can share some structures. This embodiment adopts one feasible option: the first descending channel 12 and the second descending channel are the same channel. When adopting the above scheme, after obtaining the ash material through this channel, it can be blown in different directions to send the ash material to the corresponding direct material return mechanism or storage material return mechanism.

[0055] like Figure 6As shown, the storage structure is used to store ash materials for easy adjustment of the load on the circulation channel. Its structure is not limited to a single type; this embodiment optimizes and adopts one feasible option: the storage structure includes a storage silo 29, with a third air distribution plate 28 at the bottom of the silo 29 to adjust the feeding air pressure within the silo 29; the second descending channel and the second ascending channel 14 are both located on the side of the storage silo 29 and used to convey materials into the silo 29; the return channel 26 is connected to the storage silo 29 and used to transport the materials from the storage silo 29 to the furnace body 6. When using the above scheme, multiple return channels 26 can also be provided, guiding the ash materials to the furnace body 6 under the action of air pressure and gravity.

[0056] When the boiler has been operating for a certain period of time, the total amount of ash in the circulation channel reaches a certain level, exceeding the demand for load adjustment. In this embodiment, the excess ash needs to be discharged. A feasible option is to install an ash discharge channel 27 at the storage silo 29, and an ash discharge control valve at the ash discharge channel 27. When using the above solution, the ash discharge control valve can be a gate valve.

[0057] Preferably, the ash discharge channel 27 is provided with an ash discharge gate valve 2701.

[0058] The ignition and combustion assembly, in conjunction with the furnace body 6, ignites the material. Its structure is not uniquely limited; this embodiment optimizes the design and employs one feasible option: such as... Figure 1 As shown, the ignition and combustion assembly includes an ignition burner 1, an ignition channel 2, and a water-cooled air chamber 3 connected in sequence. The water-cooled air chamber 3 is connected to a port at the lower part of the furnace body 6. The ignition and combustion assembly also includes a coal feeding device 4 and a secondary air duct 5 connected to the lower part of the furnace body 6. The furnace body 6 is also equipped with an in-furnace heating structure 7. When adopting the above scheme, the coal feeding device 4 can have multiple coal feeding ports to add materials into the furnace body 6 from multiple directions.

[0059] The tail-end enclosing mechanism is used to recover and utilize heat from the flue gas. Its structure is not limited to a single type; this embodiment optimizes and adopts one feasible option: such as... Figure 1As shown, the cyclone separator 10 has an outlet flue 9 at its top, which connects to a recovery flue 16 and transports high-temperature flue gas. The recovery flue 16 includes a superheating and reheating section 17, an economizing section 18, a denitrification section 19, and an air preheating section 20. An ash hopper 21 is located at the end of the recovery flue 16. In this configuration, the superheating and reheating section 17 contains a superheater and a reheater; the economizing section 18 contains an economizer; the denitrification section 19 can be connected to a denitrification mechanism to purify the flue gas; the air preheating section 20 contains an air preheater; and the ash hopper 21 at the end is used to collect ash materials mixed in the flue gas.

[0060] Preferably, the furnace body 6 is connected to the cyclone separator 10 through the separator inlet flue 8.

[0061] Example 2

[0062] The above-described embodiment 1 discloses a supercritical and ultra-supercritical CFB boiler capable of rapid load change. This embodiment provides a method for controlling the boiler.

[0063] A method for controlling supercritical and ultra-supercritical CFB boilers with rapid load changes, comprising:

[0064] Start the boiler to allow the material to burn in the furnace body 6 to produce flue gas and ash;

[0065] Cyclone separator 10 sends flue gas to the tail wall structure for heat recovery and centrally transports ash to the integrated storage and return device below.

[0066] When it is necessary to control and reduce the effective circulating ash in the furnace, close the control valve of the storage and return mechanism, and at the same time, select to open or close the fluidizing air of the direct ash mechanism according to the set requirements, so as to guide all or part of the ash to the storage and return mechanism for storage.

[0067] When it is necessary to control the effective circulating ash amount in the furnace, the fluidizing air of the direct return mechanism and the storage return mechanism are opened at the same time, and the control valve of the storage return mechanism is opened to guide the ash to the furnace body 6.

[0068] When the load inside the furnace reaches the specified level and runs stably, the ash discharge operation is carried out through the material storage and return mechanism to provide storage space.

[0069] The control method disclosed in this embodiment can utilize the structural characteristics of the integrated ash storage device to control the amount of ash material entering the furnace circulation channel during boiler operation, thereby adjusting the load inside the boiler. Since it is equipped with a direct ash material mechanism and a ash storage and return mechanism, it can control the ash material and quickly complete the concentration adjustment of ash material in the circulation channel, thereby completing the load adjustment of the boiler.

[0070] When implemented in this way, the following results can be achieved:

[0071] When a CFB boiler needs to rapidly reduce its load during operation, the fluidizing air in the rising section of the integrated storage and return device is activated, and the return gate valve and ash discharge gate valve are closed. Some or all of the high-temperature circulating material separated by the cyclone separator enters the storage silo for storage, rapidly reducing the effective circulating ash volume in the furnace. This reduces flow inertia and accelerates the reduction of the furnace's heat transfer coefficient, achieving a rapid response in steam parameters. When the boiler is reduced to a specified load and maintained at a stable low load, while ensuring the effective circulating ash volume meets the operating load requirements, material continues to be added to the storage silo to maintain a high material level, storing energy for rapid load increases. When the boiler needs to rapidly increase its load, the normal return feeder in the direct return zone is activated, the fluidizing air in the external bed storage silo is activated, and the return gate valve is opened. A large amount of circulating ash stored in the external bed storage silo rapidly enters the furnace through the storage return pipe to participate in circulation, quickly increasing the circulating ash volume in the furnace, increasing the material concentration in the furnace, thereby improving the furnace's heat transfer coefficient and accelerating the increase in steam parameters. When the boiler reaches the designated load and maintains a stable high load, open the ash discharge gate valve of the external bed storage silo to empty the external bed storage silo, freeing up storage space and allowing the unit to quickly reduce load and expand capacity.

[0072] The above are the embodiments listed in this example. However, this example is not limited to the optional embodiments described above. Those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments. Anyone can derive other various forms of embodiments under the guidance of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example. The scope of protection of this example should be defined in the claims.

Claims

1. A supercritical and ultra-supercritical CFB boiler capable of rapid load change, characterized in that, include: The furnace assembly includes a furnace body (6) and an ignition and combustion assembly that cooperates with the dense phase zone of the furnace body (6); The external circulation loop includes a cyclone separator (10) connected to the furnace body (6). The lower part of the cyclone separator (10) is connected to an integrated storage and return device. The integrated storage and return device includes a direct return mechanism and a storage and return mechanism. The direct return mechanism includes a first descending channel (12), a first ascending channel (13), and a return channel (15). The storage and return mechanism includes a second descending channel, a second ascending channel (14), a storage structure, and a return channel (26). Both the return channel (15) and the return channel (26) are connected to the furnace body (6). The return channel (26) is controlled by a control valve. The tail wall structure includes a recovery flue (16) that is connected to the furnace body (6) and receives the flue gas inside the furnace body (6). Several heat exchange devices are installed in the recovery flue (16). The inlet of the second descending channel is connected to the cyclone separator (10), and the outlet of the second descending channel is connected to the second ascending channel (14) to transport materials and form an upper bend connection port. An upper partition wall (22) is provided at the upper bend connection port. The second ascending channel (14) is connected to the storage structure to transport materials. A lower partition wall (23) is provided at the connection point. The upper edge of the lower partition wall (23) is higher than the lower edge of the upper partition wall (22). A second air distribution plate (25) is also provided in the second descending channel and the second ascending channel (14). The second air distribution plate (25) is used to adjust the feeding air pressure in the second descending channel and the second ascending channel (14). The storage structure includes a storage bin (29), and a third air distribution plate (28) is provided at the bottom of the storage bin (29). The third air distribution plate (28) is used to adjust the feeding air pressure in the storage bin (29). The second descending channel and the second ascending channel (14) are both located on the side of the storage bin (29) and are used to transport materials into the storage bin (29). The return channel (26) is connected to the storage bin (29) and is used to transport the materials in the storage bin (29) to the furnace body (6). The storage silo (29) is provided with an ash discharge channel (27), and an ash discharge control valve is provided at the ash discharge channel (27).

2. The supercritical and ultra-supercritical CFB boiler and control method capable of rapid load change according to claim 1, characterized in that: The inlet of the first descending channel (12) is connected to the cyclone separator (10), and the outlet of the first descending channel (12) is connected to the first ascending channel (13) to transport materials and form an upper bend connection port. An upper partition wall (22) is provided at the upper bend connection port. The first ascending channel (13) is connected to the return channel (15) to transport materials. A lower partition wall (23) is provided at the connection point. The upper edge of the lower partition wall (23) is higher than the lower edge of the upper partition wall (22). A first air distribution plate (24) is also provided in the first descending channel (12) and the first ascending channel (13). The first air distribution plate (24) is used to adjust the feeding air pressure in the first descending channel (12) and the first ascending channel (13).

3. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to claim 1 or 2, characterized in that: The number of cyclone separators (10) is several. When the number of cyclone separators (10) is one, the cyclone separator (10) is connected to both the direct return mechanism and the storage return mechanism at the same time. When the number of cyclone separators (10) is greater than one, the cyclone separator (10) is connected to either the direct return mechanism or the storage return mechanism individually, or the cyclone separator is connected to both the direct return mechanism and the storage return mechanism at the same time.

4. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to claim 1 or 2, characterized in that: The first descending channel (12) and the second descending channel are the same channel.

5. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to claim 1, characterized in that: The ignition and combustion assembly includes an ignition burner (1), an ignition channel (2), and a water-cooled air chamber (3) connected in sequence. The water-cooled air chamber (3) is connected to the port at the lower part of the furnace body (6). The ignition and combustion assembly also includes a coal feeding device (4) and a secondary air duct (5) connected to the lower part of the furnace body (6). The furnace body (6) is also provided with an in-furnace heating structure (7).

6. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to claim 1, characterized in that: The top of the cyclone separator (10) is provided with an outlet flue (9), which is connected to the recovery flue (16) and transports high-temperature flue gas. The recovery flue (16) includes a superheating and reheating section (17), a coal-saving section (18), a denitrification section (19) and an air preheating section (20). An ash hopper (21) is provided at the end of the recovery flue (16).

7. A method for controlling supercritical and ultra-supercritical CFB boilers with rapid load changes, applied to the boiler according to any one of claims 1 to 6, characterized in that, include: Start the boiler to burn the material in the furnace body (6) to produce flue gas and ash; Cyclone separator (10) sends flue gas to the tail wall structure for heat recovery and concentrates ash material to the integrated storage and return device below. When it is necessary to control and reduce the effective circulating ash in the furnace, close the control valve of the storage and return mechanism, and at the same time, select to open or close the fluidizing air of the direct return mechanism according to the set requirements, so as to guide all or part of the ash to the storage and return mechanism for storage. When it is necessary to control the effective circulating ash amount in the furnace, the fluidizing air of the direct return mechanism and the storage return mechanism are opened at the same time, and the control valve of the storage return mechanism is opened to guide the ash to the furnace body (6). When the load inside the furnace reaches the specified level and runs stably, the ash discharge operation is carried out through the material storage and return mechanism to provide storage space.

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