Supercritical and ultra-supercritical CFB (Circulating Fluidized Bed) boiler capable of quickly changing load and regulation and control method

Abstract

The invention relates to the technical field of CFB (Circulating Fluidized Bed) boilers, in particular to a supercritical and ultra-supercritical CFB boiler capable of quickly changing load and a regulation and control method. The outer circulation loop comprises a cyclone separator and an integrated material storing and returning device, and the integrated material storing and returning device comprises a direct material returning mechanism and a material storing and returning mechanism; the direct material returning mechanism comprises a first descending channel, a first ascending channel and a material returning channel; the material storing and returning mechanism comprises a second descending channel, a second ascending channel, a material storing structure and a material returning channel; the tail wall enclosure structure comprises a recovery flue, and a plurality of heat exchange devices are arranged in the recovery flue. By improving the structure of the boiler, the concentration of ash materials in a circulating channel of the boiler is regulated and controlled, and the load in the boiler is conveniently and timely regulated, so that the rapid load change of the CFB boiler is realized, and meanwhile, supercritical and ultra-supercritical main steam parameter regulation can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of CFB boilers (Circulating Fluidized Bed Boiler), and in particular to supercritical and ultra-supercritical CFB boilers capable of rapidly changing loads and a control method. Background Art

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

[0003] Based on this, thermal power units will transform from power supply of electric quantity to power supply of regulation. This requires coal-fired units to adapt to the new situation - to absorb new energy and ensure the stability and security of power grid supply through deep peak regulation and flexible operation. In some provinces with outstanding development of new energy, the demand for deep peak regulation of thermal power units is more urgent, requiring existing units to have the ability of deep peak regulation through transformation. Especially after the recent requirements for the new generation of coal-fired power indicators were put forward, the requirements for deep regulation and fast regulation of coal-fired power units were further improved, and the requirements for daytime start and stop were also put forward. This requires boilers to take corresponding measures to ensure the safety, flexibility and economy of the units during deep and fast regulation.

[0004] The deep peak-shaving technology commonly used in thermal power units now mainly achieves the dynamic balance of the power grid by deep load variation of 20% to 50% of the rated load of the thermal power units, thermal-electric decoupling, or unit start-stop. However, the peak-shaving cost of thermal power units using the start-stop method is relatively high, and frequent start-stop will also affect the life of the unit. Deep load variation technology has become the main way for thermal power units to participate in flexible peak-shaving. At present, coal-fired CFB units can usually only achieve a peak-shaving depth of 30%, and the advanced level or through certain transformation technologies can reach about 20%. The new generation of coal-fired power construction action implementation plan has put forward higher requirements for the peak-shaving depth and climbing rate of coal-fired power units, but CFB boilers have a certain disadvantage in terms of load variation due to their unique gas-solid flow and combustion mode, large thermal inertia, and more heat storage.

[0005] Unlike pulverized coal boilers, CFB boilers contain a large amount of circulating ash in the furnace, which circulates continuously in the furnace-separator-returner-furnace main loop, which has an important impact on the flow pattern, combustion and heat transfer in the furnace. A large amount of circulating ash stores most of the heat released by the fuel and circulates in the furnace, ensuring the stability and uniformity of the combustion temperature of the CFB boiler, but brings huge flow inertia to the system, causing the load change rate of the CFB boiler to be slow. The size of the flow inertia can ultimately be reflected in the speed of change of the effective circulating ash amount in the furnace, that is, the faster the effective circulating ash amount changes, the smaller the flow inertia. Therefore, how to quickly change the effective circulating ash amount in the furnace during the load change process has become one of the key issues that need to be solved to increase the CFB load change rate.

[0006] Studies have shown that particle concentration is one of the important factors affecting the heat exchange between the furnace and the heating surface of the CFB boiler, and there is a positive correlation between the heat transfer coefficient and the particle concentration. In the dilute phase region, the particle concentration and the heat transfer coefficient increase with the increase of the circulating ash amount, while in the dense phase region, after the particle concentration reaches the critical concentration of the bubbling bed, the particle concentration and the heat transfer coefficient will no longer increase with the increase of the circulating ash amount. The CFB boiler itself has a large amount of circulating ash. If the amount of circulating ash does not change during the load change process, it will bring huge heat transfer inertia to the system, resulting in a slow load change rate for the CFB boiler. Therefore, how to quickly change the effective circulating ash amount in the furnace during the load change process is an urgent problem to be solved to improve the CFB load change rate. Therefore, it is necessary to propose a more reasonable technical solution to solve the technical problems existing in the prior art. Summary of the invention

[0007] In order to overcome at least one of the defects mentioned above, the present invention proposes a supercritical and ultra-supercritical CFB boiler and a control method that can quickly change load. By adjusting and improving the material storage and return structure, flexible control of particulate matter in the combustion process is achieved, thereby adjusting the combustion situation in the furnace, and timely and quickly adjusting the circulating material load situation in the circulating furnace, thereby achieving rapid load change of the CFB boiler to meet the needs of deep peak regulation.

[0008] In order to achieve the above purpose, the boiler disclosed in the present invention can adopt the following technical solutions:

[0009] Supercritical and ultra-supercritical CFB boilers with rapid load change, including:

[0010] A furnace device, comprising a furnace body and an ignition and combustion assembly matched with a dense phase region 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 material return mechanism and a material storage and return mechanism; the direct material 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; the return channel and the return channel are both connected to the furnace body, wherein the return channel is controlled by a control valve;

[0012] The rear wall structure comprises a recovery flue which is connected with the furnace body and receives the flue gas inside the furnace body, and a plurality of heat exchange devices are arranged in the recovery flue.

[0013] The CFB boiler disclosed above regulates and returns the materials circulating in the furnace through an integrated storage and return device, effectively controls the ash concentration in the furnace, and can quickly adjust the load in the furnace. When the integrated storage and return device reduces the amount of material returned to the furnace body, the ash material concentration in the furnace decreases, which is convenient for reducing the flow inertia and accelerating the reduction of the heat transfer coefficient in the furnace, thereby achieving a rapid response of the steam parameters; when the integrated storage and return device increases the amount of material returned to the furnace body, the ash material concentration in the furnace increases, which is convenient for quickly increasing the amount of ash circulating in the furnace, increasing the material concentration in the furnace, thereby increasing the heat transfer coefficient in the furnace and accelerating the improvement of the steam parameters.

[0014] Furthermore, the direct return mechanism is used to return solid particulate matter such as ash in the circulating furnace to the furnace body for further reaction without storage. Its structure is not limited solely. It is optimized here and one of the feasible options is proposed: the inlet of the first descending channel is connected to the cyclone separator, and the outlet of the first descending channel is connected to the first ascending channel to convey materials and form an upper turning connecting port, and an upper partition wall is arranged at the upper turning connecting port; the first ascending channel is connected to the return channel to convey materials, and a lower partition wall is arranged at the connecting point, and 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 arranged in the first descending channel and the first ascending channel, and 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 the cyclone separator through a vertical pipe to receive particulate matter such as ash. At the upper turning connection port, a material isolation structure is formed by the upper partition wall. The ash reaching the upper turning connection port can form a certain backlog and cover the channel surface of the upper turning connection port, thereby maintaining the airtightness of the channel and the sealing of the circulation channel in the furnace; and the height of the lower partition wall is higher than that of the upper partition wall, which helps to increase the stacking height of the ash. When the ash enters the return channel from the ascending channel, it needs to cross a threshold, which helps to avoid air leakage at the upper turning connection port. The first air distribution plate is used to blow the ash in the upper turning connection port 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 part of the ash and other particulate materials, and can adjust the speed of returning the ash to the furnace body, so as to flexibly and quickly adjust the load in the furnace body. The material storage and return mechanism can adopt a variety of schemes, and its structure is not limited to a single one. It is optimized here and one of the feasible options is proposed: the inlet of the second descending channel is connected to the cyclone separator, and the outlet of the second descending channel is connected to the second ascending channel to convey materials and form an upper turning connecting port, and an upper partition wall is arranged at the upper turning connecting port; the second ascending channel is connected to the material storage structure to convey materials, and a lower partition wall is arranged at the connecting point, and the upper edge of the lower partition wall is higher than the lower edge of the upper partition wall; second air distribution plates are also arranged in the second descending channel and the second ascending channel, and the second air distribution plates are 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, and both are used to maintain the sealing of the channel; when the second air distribution plate is ventilated, the ash material at the upper turn connecting port is blown into the storage structure for storage, and 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 mode of the cyclone separator with the direct material return mechanism and the storage material return mechanism can adopt multiple schemes to form multiple coordination mechanisms, and its structure is not limited to a single one. Here, optimization is carried out and one of the feasible options is proposed: the number of the cyclone separators is several. When the number of cyclone separators is one, the cyclone separators are connected to coordinate with the direct material return mechanism and the storage material return mechanism at the same time; when the number of cyclone separators is greater than one, the cyclone separator is connected to coordinate with the direct material return mechanism or the storage material return mechanism alone, or the cyclone separator is connected to coordinate with the direct material return mechanism and the storage material return mechanism at the same time. When adopting the above scheme, the connection and coordination structure of the cyclone separator with the direct material return mechanism and the storage material return mechanism can be set according to the layout requirements of the actual equipment.

[0017] Furthermore, in some solutions, in order to simplify the equipment structure, the direct material return mechanism and the storage material return mechanism can share part of the structure, and one feasible option is proposed here: the first descending channel and the second descending channel are the same channel. When the above solution is adopted, after the ash material is obtained through the 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.

[0018] Furthermore, the storage structure is used to store ash materials, which is convenient for use when adjusting the load of the circulation channel. Its structure is not limited to a single one. Here, it is optimized and one of the feasible options is proposed: the storage structure includes a storage bin, and a third air distribution plate is provided at the bottom of the storage bin, and the third air distribution plate is used to adjust the feeding air pressure in the storage bin; the second descending channel and the second ascending channel are both located at the side of the storage bin and are used to transport materials into the storage bin, and the return channel is connected to the storage bin and is used to transport the materials in the storage bin to the furnace body. When the above scheme is adopted, the number of the return channels can also be set to multiple, and the ash materials are guided and transported to the furnace body under the action of wind pressure and gravity.

[0019] Furthermore, when the total amount of ash material in the circulation channel reaches a certain level after the boiler has been operating for a certain period of time and exceeds the required amount for load regulation, the excess ash material needs to be discharged. Here, a feasible option is proposed: an ash discharge channel is provided at the storage bin, and an ash discharge control valve is provided at the ash discharge channel. When the above solution is adopted, the ash discharge control valve can be a gate valve.

[0020] Furthermore, the ignition and combustion assembly cooperates with the furnace body to realize the ignition of the material, and its structure is not limited to a single one. Here, an optimization is made and one of the feasible options is proposed: the ignition and combustion assembly includes an ignition burner, an ignition channel and a water-cooled air chamber connected in sequence, and the water-cooled air chamber is connected to the port at the bottom of the furnace body; the ignition and combustion assembly also includes a coal feeding device and a secondary air pipeline connected to the bottom of the furnace body; the furnace body is also provided with a furnace heating structure. When the above scheme is adopted, the coal feeding device can use multiple coal feeding ports to add materials into the furnace body from multiple directions.

[0021] Furthermore, the tail wall wrapping mechanism is used to recycle the heat in the flue gas, and its structure is not limited to a single one. Here, an optimization is made and one of the feasible options is proposed: the top of the cyclone separator is provided with an outlet flue, which is connected to the recovery flue and transports high-temperature flue gas. The recovery flue includes a superheating and reheating section, a coal-saving section, a denitrification section and an air preheating section, and an ash hopper is provided at the end of the recovery flue. When the above scheme is adopted, a superheater and a reheater are provided in the superheating and reheating section, an economizer is provided in the coal-saving section, the denitrification section can be connected to the denitrification mechanism to purify the flue gas, and an air preheater is provided in the air preheating section. The ash hopper at the end is used to receive the ash material 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 control method of the boiler.

[0023] A control method for supercritical and ultra-supercritical CFB boilers capable of rapid load change includes:

[0024] Start the boiler to make the materials burn in the furnace to produce smoke and ash;

[0025] The cyclone separator sends the flue gas to the rear wall structure for heat recovery, and the ash is centrally transported to the integrated storage and return device below;

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

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

[0028] When the load in 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 space for material storage.

[0029] The above-disclosed control method can utilize the structural characteristics of the integrated ash storage device to control the amount of ash material entering the furnace circulation channel during the operation of the boiler, thereby adjusting the load in the boiler. Since a direct return mechanism and a storage return mechanism are provided, both the ash material can be regulated, and the concentration of the ash material in the circulation channel can be quickly adjusted, thereby completing the load adjustment of the boiler.

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

[0031] The present invention improves the structure of the boiler to achieve control of the concentration of ash materials in the boiler circulation channel, which is convenient for timely adjustment of the load in the furnace, thereby achieving rapid load change of the CFB boiler and achieving supercritical and ultra-supercritical main steam parameter adjustment. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only represent some embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

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

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

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

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

[0037] Figure 5 for Figure 4 Schematic cross-sectional view at AA in the middle.

[0038] Figure 6 for Figure 4 Schematic cross-sectional view at the middle BB.

[0039] In the above drawings, the meanings of the symbols 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. Heating structure in the furnace; 8. Separator inlet flue; 9. Exit flue; 10. Cyclone separator; 11. Vertical pipe; 12. First descending channel; 13. First ascending channel; 14. Second ascending channel; 15. Return channel; 16. Recovery flue; 17. Overheating and reheating section; 18. Coal saving 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 channel; 2601. Return gate valve; 27. Ash discharge channel; 2701. Ash discharge gate valve; 28. Third air distribution plate; 29. ​​Storage bin. DETAILED DESCRIPTION

[0041] The present embodiment is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0042] In view of the improvement of the performance requirements of the existing CFB boilers, the demand for variable load is relatively large, but the traditional CFB boilers cannot well meet the demand for variable load. The following embodiments are adjusted and overcome the defects in the prior art.

[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] A furnace device, comprising a furnace body 6 and an ignition and combustion assembly matched with a dense phase region 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 material storage and return device, and the integrated material storage and return device includes a direct material return mechanism and a material storage and return mechanism; the direct material return mechanism includes a first descending channel 12, a first ascending channel 13 and a return channel 15, and the material storage and return mechanism includes a second descending channel, a second ascending channel 14, a material storage structure and a return channel 26; the return channel 15 and the return channel 26 are both connected to the furnace body 6, and the return channel 26 is controlled by a control valve;

[0047] The rear wall structure includes a recovery flue 16 which is connected to the furnace body 6 and receives the flue gas inside the furnace body 6 . A plurality of heat exchange devices are arranged 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 regulates and returns the materials circulating in the furnace through an integrated storage and return device, effectively controls the ash concentration in the furnace, and can quickly adjust the load in the furnace. When the integrated storage and return device reduces the amount of return to the furnace body 6, the ash material concentration in the furnace decreases, which is convenient for reducing the flow inertia and accelerating the reduction of the heat transfer coefficient in the furnace, thereby achieving a rapid response of the steam parameters; when the integrated storage and return device increases the amount of return to the furnace body 6, the ash material concentration in the furnace increases, which is convenient for quickly increasing the amount of ash circulating in the furnace, increasing the material concentration in the furnace, thereby increasing the heat transfer coefficient in the furnace and accelerating the improvement of the steam parameters.

[0050] like Figure 2 to Figure 6 As shown, the direct return mechanism is used to return solid particulate matter such as ash in the circulating furnace to the furnace body 6 for further reaction without storage. Its structure is not limited to a single one. This embodiment is optimized and adopts one of the feasible options: 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 convey materials and form an upper turning connecting port, and an upper partition wall 22 is arranged at the upper turning connecting port; the first ascending channel 13 is connected to the return channel 15 to convey materials, and a lower partition wall 23 is arranged at the connecting 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 arranged in the first descending channel 12 and the first ascending channel 13, and 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 vertical pipe 11 to receive particulate matter such as ash. At the upper turning connection port, an isolation structure of the material is formed by the upper partition wall 22. The ash reaching the upper turning connection port can form a certain backlog and cover the channel surface of the upper turning connection port, thereby maintaining the airtightness of the channel and the airtightness of the circulation channel in the furnace; and the height of the lower partition wall 23 is higher than that of the upper partition wall 22, which helps to increase the stacking height of the ash. When the ash enters the return channel 15 from the ascending channel, it needs to cross a threshold, which helps to avoid air leakage at the upper turning connection port. The first air distribution plate 24 is used to blow the ash in the upper turning connection port 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 turning edge described in this embodiment is set to 100 mm to 500 mm.

[0052] like Figure 2 to Figure 6As shown, the material storage and return mechanism is used to store part of the ash and other particulate matter, and can adjust the speed of the material returning to the furnace body 6, so as to flexibly and quickly adjust the load in the furnace body 6. The material storage and return mechanism can adopt a variety of schemes, and its structure is not limited to a single one. This embodiment is optimized and adopts one of the feasible options: 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 convey the material and form an upper turning connecting port, and an upper partition wall 22 is arranged at the upper turning connecting port; the second ascending channel 14 is connected to the material storage structure to convey the material, and a lower partition wall 23 is arranged at the connecting point, and the upper edge of the lower partition wall 23 is higher than the lower edge of the upper partition wall 22; the second descending channel and the second ascending channel 14 are also provided with a second air distribution plate 25, and 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 mechanism, and are both used to maintain the sealing of the channel; when the second air distribution plate 25 is ventilated, the ash material at the upper turn connecting port is blown into the storage structure for storage, and when the return channel 26 is opened, the ash material in the storage structure can enter the furnace body 6 through the return channel 26.

[0053] like Figure 2 As shown, the coordination mode of the cyclone separator 10 with the direct material return mechanism and the storage material return mechanism can adopt multiple schemes to form multiple coordination mechanisms, and its structure is not limited to a single one. This embodiment is optimized and adopts one of the feasible options: the number of the cyclone separators 10 is several. When the number of the cyclone separators 10 is one, the cyclone separator 10 is connected to coordinate with the direct material return mechanism and the storage material return mechanism at the same time; when the number of the cyclone separators 10 is greater than one, the cyclone separator 10 is connected to coordinate with the direct material return mechanism or the storage material return mechanism alone, or the cyclone separator is connected to coordinate with the direct material return mechanism and the storage material return mechanism at the same time. When adopting the above scheme, the connection and coordination structure of the cyclone separator 10 with the direct material return mechanism and the storage material return mechanism can be set according to the layout requirements of the actual equipment.

[0054] like Figure 2 to Figure 6 As shown, in some schemes, in order to simplify the equipment structure, the direct material return mechanism and the storage material return mechanism can share part of the structure. This embodiment adopts one of the feasible options: the first descending channel 12 and the second descending channel are the same channel. When the above scheme is adopted, after the ash material is obtained through the 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, which is convenient for use when adjusting the load of the circulation channel. Its structure is not limited to the only one. This embodiment is optimized and adopts one of the feasible options: 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 at 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. When the above scheme is adopted, the number of the return channels 26 can also be set to multiple, and the ash materials are guided and transported to the furnace body 6 under the action of wind pressure and gravity.

[0056] When the boiler has been operating for a certain period of time, the total amount of ash material in the circulation channel reaches a certain level and exceeds the required amount of load regulation, the excess ash material needs to be discharged. This embodiment adopts a feasible option: the storage bin 29 is provided with an ash discharge channel 27, and the ash discharge channel 27 is provided with an ash discharge control valve. When the above solution is adopted, 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 cooperates with the furnace body 6 to realize the ignition of the material. Its structure is not limited to a single one. This embodiment is optimized and adopts one of the feasible options: 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, and 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 pipeline 5 connected to the lower part of the furnace body 6; the furnace body 6 is also provided with a furnace heating structure 7. When the above scheme is adopted, the coal feeding device 4 can adopt multiple coal feeding ports to add materials into the furnace body 6 from multiple directions.

[0059] The tail wall wrapping mechanism is used to recycle the heat in the flue gas, and its structure is not limited to a single one. This embodiment is optimized and adopts one of the feasible options: Figure 1As shown, the top of the cyclone separator 10 is provided with an outlet flue 9, which is connected to the recovery flue 16 and conveys 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, and an ash hopper 21 is provided at the end of the recovery flue 16. When the above scheme is adopted, a superheater and a reheater are provided in the superheating and reheating section 17, an economizer is provided in the coal-saving section 18, the denitrification section 19 can be connected to the denitrification mechanism to purify the flue gas, and an air preheater is provided in the air preheating section 20. The ash hopper 21 at the end is used to receive the ash material 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-mentioned embodiment 1 discloses a supercritical and ultra-supercritical CFB boiler capable of rapid load change. This embodiment provides a control method for the boiler.

[0063] A supercritical and ultra-supercritical CFB boiler control method capable of rapidly changing loads, comprising:

[0064] Start the boiler to burn the materials in the furnace body 6 to produce smoke and ash;

[0065] The cyclone separator 10 sends the flue gas to the rear wall structure for heat recovery, and centrally transports the ash to the integrated storage and return device below;

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

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

[0068] When the load in 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 space for material storage.

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

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

[0071] When the CFB boiler needs to reduce the load quickly during operation, the fluidizing air in the rising section of the storage and return area of ​​the integrated storage and return device is turned on, the return gate valve and the ash discharge gate valve are closed, and part or all of the high-temperature circulating materials separated by the cyclone separator are stored in the storage bin, which quickly reduces the effective circulating ash in the furnace, reduces the flow inertia, and accelerates the reduction of the heat transfer coefficient in the furnace, so as to achieve a rapid response of steam parameters. When the boiler is reduced to the specified load and maintains stable operation at a low load, on the premise of ensuring that the effective circulating ash in the furnace meets the operating load requirements, continue to store materials in the storage bin to ensure that the storage bin maintains a high material level and accumulate energy for the unit to quickly increase the load. When the boiler needs to increase the load quickly, the normal return device in the return area is directly returned, the fluidizing air of the external bed storage bin is turned on, and the return gate valve is opened. A large amount of circulating ash stored in the external bed storage bin quickly enters the furnace through the storage return pipe to participate in the circulation, quickly increasing the circulating ash in the furnace, increasing the material concentration in the furnace, thereby increasing the heat transfer coefficient in the furnace and accelerating the improvement of steam parameters. When the boiler reaches the specified load and maintains stable operation at high load, open the ash discharge gate valve of the external bed storage bin to empty the external bed storage bin and free up storage space to quickly reduce load and expand capacity of the unit.

[0072] The above are the implementation methods listed in this embodiment, but this embodiment is not limited to the above optional implementation methods. Those skilled in the art can arbitrarily combine the above methods to obtain other various implementation methods. Anyone can derive other various implementation methods under the inspiration of this embodiment. The above specific implementation methods should not be understood as limiting the protection scope of this embodiment. The protection scope of this embodiment should be based on the definition in the claims.

Claims

1. Supercritical and ultra-supercritical CFB boilers capable of rapid load change, characterized in that: include: A furnace device, comprising a furnace body (6) and an ignition and combustion assembly matched with a dense phase region of the furnace body (6); An external circulation loop comprises a cyclone separator (10) connected to a furnace body (6); the lower part of the cyclone separator (10) is connected to an integrated material storage and return device; the integrated material storage and return device comprises a direct material return mechanism and a material storage and return mechanism; the direct material return mechanism comprises a first descending channel (12), a first ascending channel (13) and a return channel (15); the material storage and return mechanism comprises a second descending channel, a second ascending channel (14), a material storage structure and a return channel (26); the return channel (15) and the return channel (26) are both connected to the furnace body (6); the return channel (26) is controlled to be on and off by a control valve; The rear wall structure comprises a recovery flue (16) which is connected to the furnace body (6) and receives the flue gas inside the furnace body (6), and a plurality of heat exchange devices are arranged in the recovery flue (16).

2. The supercritical and ultra-supercritical CFB boiler capable of rapid load change and the control method according to claim 1 are 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 convey materials and form an upper connecting port, and an upper partition wall (22) is arranged at the upper connecting port; the first ascending channel (13) is connected to the return channel (15) to convey materials, and a lower partition wall (23) is arranged at the connecting 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 arranged in the first descending channel (12) and the first ascending channel (13), and 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, characterized in that: 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 convey materials and form an upper connecting port, and an upper partition wall (22) is arranged at the upper connecting port; the second ascending channel (14) is connected to the material storage structure to convey materials, and a lower partition wall (23) is arranged at the connecting point, and 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 arranged in the second descending channel and the second ascending channel (14), and 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).

4. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to any one of claims 1 to 3, characterized in that: There are a number of cyclone separators (10). When the number of cyclone separators (10) is one, the cyclone separators (10) are simultaneously connected to cooperate with the direct material return mechanism and the storage material return mechanism; when the number of cyclone separators (10) is greater than one, the cyclone separators (10) are individually connected to cooperate with the direct material return mechanism or the storage material return mechanism, or the cyclone separators are simultaneously connected to cooperate with the direct material return mechanism and the storage material return mechanism.

5. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to any one of claims 1 to 3, characterized in that: The first descending channel (12) and the second descending channel are the same channel.

6. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to claim 1, characterized in that: The material storage structure includes a material storage bin (29), and a third air distribution plate (28) is arranged at the bottom of the material storage bin (29), and the third air distribution plate (28) is used to adjust the feeding air pressure in the material storage bin (29); the second descending channel and the second ascending channel (14) are both located on the side of the material storage bin (29) and are used to transport materials into the material storage bin (29); the return channel (26) is connected to the material storage bin (29) and is used to transport the materials in the material storage bin (29) to the furnace body (6).

7. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to claim 6, characterized in that: The storage bin (29) is provided with an ash discharge channel (27), and the ash discharge channel (27) is provided with an ash discharge control valve.

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

9. The supercritical and ultra-supercritical CFB boiler capable of rapid load change according to claim 1, characterized in that: An outlet flue (9) is arranged at the top of the cyclone separator (10), and the outlet flue (9) is connected to a recovery flue (16) and conveys 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 arranged at the end of the recovery flue (16).

10. A method for controlling supercritical and ultra-supercritical CFB boilers capable of rapid load change, characterized in that: include: Starting the boiler to allow materials to burn in the furnace body (6) to generate smoke and ash; The cyclone separator (10) sends the flue gas to the rear wall structure for heat recovery, and centrally transports the ash to the integrated storage and return device below; When it is necessary to control and reduce the effective circulating ash volume in the furnace, close the control valve of the storage and return mechanism, and at the same time, open or close the fluidizing air of the direct return mechanism according to the set requirements, and guide all or part of the ash to the storage and return mechanism for storage; When it is necessary to control and increase the effective circulating ash volume in the furnace, the fluidizing air of the direct material return mechanism and the material storage and material return mechanism is opened at the same time, and the control valve of the material storage and material return mechanism is opened to guide the ash to the furnace body (6); When the load in 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 space for material storage.

Images