Circulating fluidized bed boiler

Abstract

The utility model relates to the technical field of steam boilers, in particular to a circulating fluidized bed boiler which comprises a rack and a hearth fixedly arranged on the rack, and further comprises an air preheater, an igniter, a cyclone separator, a return feeder and an economizer which are fixedly arranged on the rack. A fluidized bed air distribution plate and a water cooling structure are arranged in the hearth, the fluidized bed air distribution plate is located on the inner side of the water cooling structure, a feeding pipeline is obliquely arranged on the hearth, the air preheater and the igniter are both fixedly connected and communicated with the hearth, and the cyclone separator and the return feeder are both fixedly connected and communicated with the hearth. And the economizer is fixedly connected and communicated with the hearth, the air preheater and the water cooling structure. According to the circulating fluidized bed boiler, the igniter realizes automatic ignition, so that the labor intensity of manual operation during operation of the boiler is effectively reduced; high-temperature flue gas exchanges heat with the water cooling structure to generate a large amount of high-temperature steam, and the heat exchange efficiency is high.

Description

Technical Field

[0001] This utility model relates to the field of steam boiler technology, specifically to a circulating fluidized bed boiler. Background Technology

[0002] Circulating fluidized bed (CFB) boilers utilize the most advanced clean coal combustion technology in industrial applications. The main structure of a CFB boiler consists of two parts: a combustion chamber (including dense and dilute phase zones) and a circulating recirculation system (including a high-temperature gas-solid separator and a return system). The biggest difference between CFB boilers and bubbling fluidized bed combustion technology is the higher operating velocity, which enhances heterogeneous reaction processes such as combustion and desulfurization. Boiler capacity can be expanded to large capacities acceptable to the power industry (600MW or higher). CFB boilers have effectively solved fundamental problems in thermodynamics, mechanics, and materials science, as well as engineering problems such as expansion, wear, and overheating, making them an advanced technology for the energy utilization of difficult-to-burn solid fuels (such as coal gangue, oil shale, municipal waste, sludge, and other waste materials). However, existing CFB boilers require manual ignition, and their heat exchange efficiency is low, resulting in a small amount of high-temperature steam production. Therefore, a new CFB boiler is urgently needed to address these issues. Utility Model Content

[0003] To address the technical problems of existing circulating fluidized bed boilers, such as the need for manual ignition, low heat exchange efficiency, and insufficient production of high-temperature steam, this invention provides a circulating fluidized bed boiler with an igniter that enables automatic ignition, effectively reducing the labor intensity of manual operation during boiler operation; high-temperature flue gas exchanges heat with the water-cooled structure to generate a large amount of high-temperature steam, resulting in high heat exchange efficiency.

[0004] This utility model provides a circulating fluidized bed boiler, including a frame and a furnace fixedly mounted on the frame. It also includes an air preheater, an igniter, a cyclone separator, a return feeder, and an economizer, all fixedly mounted on the frame. The furnace interior is equipped with a fluidized bed air distribution plate and a water-cooling structure, with the air distribution plate located inside the water-cooling structure. An inclined feed pipe is arranged on the furnace. The air preheater and igniter are both fixedly connected to and communicate with the furnace. The cyclone separator and the return feeder are fixedly connected to and communicate with each other, and both are fixedly connected to and communicate with the furnace. The economizer is fixedly connected to and communicates with the furnace, the air preheater, and the water-cooling structure.

[0005] Furthermore, the furnace is provided with a first irregular cavity and a second irregular cavity that communicate with each other. The fluidized bed air distribution plate is located in the first irregular cavity. The water-cooling structure is located in the first irregular cavity and the second irregular cavity, and the fluidized bed air distribution plate is located inside part of the water-cooling structure. The bottom of the feed pipe, air preheater, igniter and return feeder are all connected to the first irregular cavity. The top of the cyclone separator is connected to both the second irregular cavity and the first irregular cavity. The air inlet of the economizer is connected to the second irregular cavity. The air outlet of the economizer is connected to the exhaust gas inlet of the air preheater.

[0006] Furthermore, the water-cooled structure includes a first membrane water-cooled wall, an upper header, a lower header, a second membrane water-cooled wall, an upper boiler drum, and a lower boiler drum, all fixedly connected and communicating with each other. The first membrane water-cooled wall is fixedly installed on the inner wall of the first irregular cavity, and the fluidized bed air distribution plate is located inside the first membrane water-cooled wall. The upper header is fixedly installed on the frame, and the second membrane water-cooled wall is fixedly installed on the inner wall of the second irregular cavity. The upper boiler drum and the lower boiler drum are fixedly installed on the furnace. The upper header is also fixedly connected and communicating with the upper boiler drum through a steam pipe. The outlet of the economizer is fixedly connected and communicating with the upper boiler drum. A steam-water separator is fixedly installed on the upper boiler drum.

[0007] Furthermore, the first membrane water-cooled wall penetrates the first irregular cavity. The top and bottom of the first membrane water-cooled wall are fixedly connected to and communicate with the upper header and lower header, respectively. The upper boiler drum is fixedly connected to and communicates with the lower boiler drum through the second membrane water-cooled wall. The upper header is fixedly connected to and communicates with the upper boiler drum, and the lower header is fixedly connected to and communicates with the lower boiler drum. External cooling water flows in the first membrane water-cooled wall, the upper header, and the lower header, as well as in the second membrane water-cooled wall, the upper boiler drum, and the lower boiler drum.

[0008] Furthermore, multiple upper and lower headers are provided, each fixedly connected and communicating with the top and bottom of the first membrane water-cooled wall. Some of the upper and lower headers are also fixedly connected to the furnace. Multiple upper headers are fixedly connected and communicating with the upper boiler drum via steam pipes. The provision of multiple upper and lower headers ensures that the first membrane water-cooled wall is filled with cooling water, guaranteeing efficient heat exchange.

[0009] Furthermore, two economizers are provided, fixedly connected and communicating with each other. The air inlet of the upper economizer communicates with the second irregular cavity, the air outlet of the lower economizer communicates with the exhaust gas inlet of the air preheater, and the water outlet of the upper economizer is fixedly connected and communicating with the upper boiler drum. Having two economizers further facilitates heat exchange between the high-temperature flue gas and cooling water, maximizing the absorption of heat from the high-temperature flue gas.

[0010] Furthermore, the connection points between the feed pipe and the furnace, the cyclone separator and the furnace, and the return feeder and the furnace are all located above the fluidized bed air distribution plate, while the connection points between the air preheater and the furnace, and the igniter and the furnace, are all located below the fluidized bed air distribution plate.

[0011] Furthermore, a connecting pipe is fixedly installed on the frame. The connecting pipe is fixedly connected to the bottom of the furnace and communicates with the first irregular cavity. The connection point between the connecting pipe and the furnace is located below the fluidized bed air distribution plate. The air outlets of the igniter and the air preheater are both fixedly connected to and communicate with the connecting pipe. When the igniter is activated, a high-temperature flame is generated. The high-temperature flame enters the first irregular cavity through the connecting pipe. At the same time, the heat-exchanged external air enters the first irregular cavity through the air outlet of the air preheater and the connecting pipe.

[0012] Furthermore, the return feeder includes a first return feed pipe, a second return feed pipe, and a third return feed pipe fixedly mounted on the frame and communicating with each other. The first return feed pipe is fixedly connected to and communicates with the bottom of the cyclone separator. A backflush pipe is fixedly mounted on the first return feed pipe. The third return feed pipe is fixedly connected to the furnace and communicates with the first shaped cavity. The cyclone separator is inclined in the third return feed pipe to separate solid particles and high-temperature flue gas. The high-temperature flue gas continues to float upward and enters the second shaped cavity. The solid particles return to the first shaped cavity through the first, second, and third return feed pipes for cyclic combustion.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] Material falls through the feed pipe onto the fluidized bed air distribution plate inside the furnace. External cooling water, preheated by the economizer, enters the water-cooled structure. The igniter starts, and simultaneously, external air, preheated by the air preheater, enters the furnace. Combustion is injected into the furnace and mixes with the air to produce a flame. The flame burns the material, generating solid particles and high-temperature flue gas. These particles and gas rise and fall to the cyclone separator, which separates them. The high-temperature flue gas continues to rise, while the solid particles return to the first shaped cavity for recirculation and combustion. The generated high-temperature flue gas exchanges heat with the cooling water in the water-cooled structure, producing a high-temperature steam-water mixture. After steam-water separation, this mixture forms a large amount of high-temperature steam, which is ultimately discharged for further utilization. The high-temperature flue gas, after heat exchange, finally passes through the economizer and air preheater for further heat exchange before being released into the atmosphere.

[0015] The circulating fluidized bed boiler of this utility model,

[0016] The igniter generates a high-temperature flame. External air, preheated by an air preheater, enters the first shaped cavity. The high-temperature flame burns the material on the fluidized bed air distribution plate, producing solid particles and high-temperature flue gas. The external air provides oxygen for the combustion of the high-temperature flame and simultaneously passes through the fluidized bed air distribution plate, maintaining uniformity and driving the solid particles and high-temperature flue gas in fluidized motion. The solid particles and high-temperature flue gas float upwards and downwards to the cyclone separator, where they separate. The high-temperature flue gas continues to float upwards, while the solid particles return to the first shaped cavity via a return feeder for cyclic combustion. The generated high-temperature flue gas exchanges heat with the cooling water in the water-cooled structure, producing a high-temperature steam-water mixture. The steam-water separator separates the steam and water from the mixture, forming a large amount of high-temperature steam, which is then discharged. This high-temperature steam can be reused later. The igniter achieves automatic ignition, effectively reducing the labor intensity of manual operation during boiler operation; the high-temperature flue gas exchanges heat with the water-cooled structure to produce a large amount of high-temperature steam, resulting in high heat exchange efficiency. Attached Figure Description

[0017] Figure 1 This is a cross-sectional structural schematic diagram of a circulating fluidized bed boiler according to the present invention;

[0018] Figure 2 This is a utility model Figure 1 Enlarged structural diagram of A in the middle;

[0019] The numbers in the attached diagram are:

[0020] 1. Frame; 11. Connecting pipes; 2. Furnace; 21. Fluidized bed air distribution plate; 22. Feed pipe; 23. First irregular cavity; 24. Second irregular cavity; 3. Air preheater; 4. Ignition device; 5. Cyclone separator; 6. Return feeder; 61. First return pipe; 62. Second return pipe; 63. Third return pipe; 7. Economizer; 8. Water-cooled structure; 81. First membrane water-cooled wall; 82. Upper header; 83. Lower header; 84. Second membrane water-cooled wall; 85. Upper drum; 86. Lower drum; 87. Steam pipe; 9. Steam-water separator. Detailed Implementation

[0021] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0022] like Figures 1-2As shown, a circulating fluidized bed boiler includes a frame 1 and a furnace 2 fixedly mounted on the frame 1. The frame 1 is equipped with a maintenance ladder for easy maintenance and inspection. The boiler also includes an air preheater 3, an igniter 4, a cyclone separator 5, a return feeder 6, and an economizer 7, all fixedly mounted on the frame 1. The furnace 2 contains a fluidized bed air distribution plate 21 and a water-cooled structure 8, with the air distribution plate 21 located inside the water-cooled structure 8. An inclined feed pipe 22 is installed on the furnace 2. The air preheater 3 and the igniter 4 are both fixedly connected to and communicate with the furnace 2. The cyclone separator 5 and the return feeder 6 are both fixedly connected to and communicate with the furnace 2. The economizer 7 is fixedly connected to and communicates with the furnace 2, the air preheater 3, and the water-cooled structure 8. The connection points of the feed pipe 22 with the furnace 2, the cyclone separator 5 with the furnace 2, and the return feeder 6 with the furnace 2 are all located above the fluidized bed air distribution plate 21. The connection points of the air preheater 3 with the furnace 2 and the igniter 4 with the furnace 2 are all located below the fluidized bed air distribution plate 21. It should be noted that the positions of the fluidized bed air distribution plate 21, the water-cooled structure 8, and the feed pipe 22 do not interfere with each other. The structure and operation of the air preheater 3, igniter 4, cyclone separator 5, economizer 7, and fluidized bed air distribution plate 21 are existing technologies and will not be described in detail here. Generally, gas is supplied to the igniter 4 via a gas pipeline.

[0023] The working process of the circulating fluidized bed boiler: The material (coal) falls into the fluidized bed air distribution plate 21 inside the furnace 2 through the feed pipe 22. The external cooling water is preheated by the economizer 7 (external cooling water exchanges heat with the high-temperature flue gas passing through the economizer 7) and then enters the water-cooled structure 8. The igniter 4 starts to generate a high-temperature flame. At the same time, the external air is preheated by the air preheater 3 (external air exchanges heat with the high-temperature flue gas passing through the air preheater 3) and then enters the furnace 2. The high-temperature flame burns the material on the fluidized bed air distribution plate 21 and produces solid particles and high-temperature flue gas. The external air provides oxygen for the high-temperature flame combustion. At the same time, the external air also passes through the fluidized bed air distribution plate 21 and is kept uniform, driving the solid particles and high-temperature flue gas to fluidize. The solid particles and high-temperature flue gas float up and down to the cyclone separator 5. The cyclone separator 5 separates the solid particles and high-temperature flue gas. The high-temperature flue gas continues to float upward, while the solid particles return to the first irregular cavity 23 through the return feeder 6 for circulating combustion. The generated high-temperature flue gas exchanges heat with the cooling water in the water-cooled structure 8 to produce a high-temperature steam-water mixture. After steam-water separation, the high-temperature steam is formed into a large amount of high-temperature steam, which is eventually discharged for further utilization. The high-temperature flue gas after heat exchange finally passes through the economizer 7 and the air preheater 3 for further heat exchange before being discharged into the atmosphere.

[0024] In this embodiment of the circulating fluidized bed boiler, the igniter 4 enables automatic ignition, effectively reducing the labor intensity of manual operation during boiler operation; the high-temperature flue gas exchanges heat with the water-cooled structure 8 to generate a large amount of high-temperature steam, resulting in high heat exchange efficiency.

[0025] In one possible implementation, the furnace 2 is provided with a first irregular cavity 23 and a second irregular cavity 24 that communicate with each other. The fluidized bed air distribution plate is located in the first irregular cavity 23. The water-cooling structure 8 is located in the first irregular cavity 23 and the second irregular cavity 24, and the fluidized bed air distribution plate 21 is located inside part of the water-cooling structure 8. The bottom of the feed pipe 22, the air preheater 3, the igniter 4, and the return feeder 6 are all connected to the first irregular cavity 23. The top of the cyclone separator 5 is connected to the first irregular cavity 24. The second irregular cavity 24 and the first irregular cavity 23 are both connected. The connection points between the feed pipe 22 and the furnace 2, the cyclone separator 5 and the furnace 2, and the return feeder 6 and the furnace 2 are all located above the fluidized bed air distribution plate 21. The connection points between the air preheater 3 and the furnace 2, and between the igniter 4 and the furnace 2, are all located below the fluidized bed air distribution plate 21. The air inlet of the economizer 7 is connected to the second irregular cavity 24, and the air outlet of the economizer 7 is connected to the exhaust gas inlet of the air preheater 3. The exhaust gas outlet of the air preheater 3 is used to discharge low-temperature flue gas; the air inlet of the air preheater 3 is used to introduce external air; and the air outlet of the air preheater 3 is connected to the first irregular cavity 23.

[0026] Ignition 4 starts to generate a high-temperature flame. External air, preheated by air preheater 3, enters the first shaped cavity 23. The high-temperature flame burns the material on the fluidized bed air distribution plate 21, producing solid particles and high-temperature flue gas. The solid particles and high-temperature flue gas float up and down in the first shaped cavity 23 to the cyclone separator 5, where they separate. The high-temperature flue gas continues to float upwards into the second shaped cavity 24, while the solid particles return to the first shaped cavity 23 via the return feeder 6 for cyclic combustion. In effect, the high-temperature flue gas exchanges heat with the cooling water in the water-cooled structure 8 in the first and second shaped shaped cavities 23 and 24, producing a high-temperature steam-water mixture. After heat exchange, the high-temperature flue gas enters the economizer 7 and air preheater 3 from the second shaped cavity 24 for further heat exchange before being discharged into the atmosphere.

[0027] In one possible implementation, the water-cooled structure 8 includes a first membrane water-cooled wall 81, an upper header 82, a lower header 83, a second membrane water-cooled wall 84, an upper boiler drum 85, and a lower boiler drum 86, all fixedly connected and communicating with each other. The first membrane water-cooled wall 81 is fixedly installed on the inner wall of the first irregular cavity 23, and the fluidized bed air distribution plate 21 is located inside the first membrane water-cooled wall 81. The upper header 82 is fixedly installed on the frame 1, and the second membrane water-cooled wall 84 is fixedly installed on the inner wall of the second irregular cavity 24. The upper boiler drum 85 and the lower boiler drum 86 are fixedly installed on the furnace 2. The upper header 82 is also fixedly connected and communicating with the upper boiler drum 85 through a steam pipe 87. The outlet of the economizer 7 is fixedly connected and communicating with the upper boiler drum 85, and the inlet of the economizer 7 is used to introduce external cooling water. A steam-water separator 9 is fixedly installed on the upper boiler drum 85. The structure and operation of the steam-water separator 9, the first membrane water-cooled wall 81, and the second membrane water-cooled wall 84 are existing technologies and will not be described in detail here. The first membrane water-cooled wall 81 and the second membrane water-cooled wall 84 are square, fully sealed water-cooled walls, providing good boiler sealing and facilitating efficient combustion and heat exchange. It should be noted that the external cooling water, after preheating by the economizer 7, enters the upper drum 85. Ultimately, the external cooling water flows through the first membrane water-cooled wall 81, the upper header 82, and the lower header 83, as well as the second membrane water-cooled wall 84, the upper drum 85, and the lower drum 86.

[0028] High-temperature flue gas exchanges heat with cooling water in the first membrane water-cooled wall 81, upper header 82, and lower header 83 to generate a high-temperature steam-water mixture. The high-temperature flue gas also exchanges heat with cooling water in the second membrane water-cooled wall 84, upper drum 85, and lower drum 86 to generate another high-temperature steam-water mixture. This mixture is ultimately transported to the upper drum 85 via steam pipe 87. The high-temperature steam-water mixture is located in the upper part of the upper drum 85 (occupying one-third of the total area of ​​the upper drum 85). The steam-water separator 9 separates the high-temperature steam-water mixture, forming a large amount of high-temperature steam, which is then discharged. This high-temperature steam can be reused later.

[0029] Preferably, a guide plate is provided on the inner wall of the second irregular cavity 24. The guide plate does not interfere with the position of the second membrane water-cooled wall 84, which further facilitates the entry of high-temperature flue gas from the second irregular cavity 24 into the economizer 7.

[0030] In one possible implementation, the first membrane water-cooled wall 81 penetrates the first irregular cavity 23. The top and bottom of the first membrane water-cooled wall 81 are fixedly connected to and communicate with the upper header 82 and the lower header 83, respectively. The upper boiler drum 85 is fixedly connected to and communicates with the lower boiler drum 86 through the second membrane water-cooled wall 84. The lower header 83 is fixedly connected to and communicates with the lower boiler drum 86. External cooling water flows in the first membrane water-cooled wall 81, the upper header 82, and the lower header 83, as well as in the second membrane water-cooled wall 84, the upper boiler drum 85, and the lower boiler drum 86. Because the upper header 82 is fixedly mounted on the frame 1, and the first membrane water-cooled wall 81 is fixedly mounted on the inner wall of the first irregular cavity 23, the lower header 83, although suspended, remains stable.

[0031] Preferably, the lower header 83 and the lower boiler drum 86 are connected through multiple first pipes.

[0032] As one possible implementation, multiple upper headers 82 and lower headers 83 are provided. Each upper header 82 and lower header 83 is fixedly connected to and communicates with the top and bottom of the first membrane water-cooled wall 81, respectively. Some of the upper headers 82 and lower headers 83 are also fixedly connected to the furnace 2. Multiple upper headers 82 are fixedly connected to and communicate with the upper boiler drum 85 via steam pipes 87. The provision of multiple upper headers 82 and lower headers 83 ensures that the first membrane water-cooled wall 81 is filled with cooling water, guaranteeing efficient heat exchange. The fixed connection of some upper headers 82 and lower headers 83 to the furnace 2 further ensures the stability of the lower headers 83. In this embodiment, the upper headers 82 are locked to the frame 1 via connecting rods, and some upper headers 82 are also fixedly connected to the furnace 2, ultimately achieving the hanging and fixing of the furnace 2 onto the frame 1. Preferably, there are three upper headers 82, one of which is also fixedly connected to the furnace 2; there are four lower headers 83, two of which are also fixedly connected to the furnace 2.

[0033] In one possible implementation, two economizers 7 are provided, fixedly connected and communicating with each other, and the two economizers 7 are fixedly connected and communicating with each other through a second pipe; the air inlet of the upper economizer 7 communicates with the second irregular cavity 24, the air outlet of the lower economizer 7 communicates with the exhaust gas inlet of the air preheater 3, the water outlet of the upper economizer 7 is fixedly connected and communicating with the upper boiler drum 85, and the water inlet of the lower economizer 7 is used to introduce cold water. Having two economizers 7 further facilitates heat exchange between high-temperature flue gas and cooling water, maximizing the absorption of heat from the high-temperature flue gas. In this embodiment, the economizer 7 adopts a semi-fin structure, which is beneficial for heat exchange and ash removal.

[0034] External cooling water passes through the inlet of the lower economizer 7 and then sequentially through two economizers 7. The high-temperature flue gas, after heat exchange, passes through the second irregular cavity 24 and the inlet of the upper economizer 7, passing through two economizers 7 in sequence. The high-temperature flue gas and cooling water exchange heat again in the economizers 7, resulting in a further decrease in flue gas temperature and an increase in external cooling water temperature. The high-temperature flue gas then enters the air preheater 3 through the outlet of the lower economizer 7, while the cooling water enters the upper boiler drum 85 through the outlet of the upper economizer 7. Through the upper boiler drum 85, the cooling water is distributed to the first membrane water-cooled wall 81, the upper header 82, the lower header 83, the second membrane water-cooled wall 84, and the lower boiler drum 86.

[0035] External air enters the air preheater 3 through its air inlet. The high-temperature flue gas, after heat exchange, enters the air preheater 3 through the outlet of the economizer 7 located below and the exhaust gas inlet of the air preheater 3. The high-temperature flue gas and external air exchange heat again in the air preheater 3. After three heat exchanges, the temperature of the high-temperature flue gas decreases again, forming low-temperature flue gas, while the temperature of the external air increases. The low-temperature flue gas is finally discharged into the atmosphere through the exhaust gas outlet of the air preheater 3. The external air, after heat exchange, finally enters the first irregular cavity 23 through the air outlet of the air preheater 3.

[0036] Preferably, a water pump is provided, which is connected to the outlet of the lower economizer 7 and the upper boiler drum 85 through a third pipe. The water pump pumps the cooling water in the economizer 7 to the upper boiler drum 85.

[0037] In one possible implementation, a connecting pipe 11 is fixedly installed on the frame 1. The connecting pipe 11 is fixedly connected to the bottom of the furnace 2 and communicates with the first irregular cavity 23. The connection point between the connecting pipe 11 and the furnace 2 is located below the fluidized bed air distribution plate 21. The igniter 4 is fixedly connected to and communicates with the connecting pipe 11. The air outlet of the air preheater 3 is fixedly connected to and communicates with the connecting pipe 11. When the igniter 4 is activated, a high-temperature flame is generated. The high-temperature flame enters the first irregular cavity 23 through the connecting pipe 11. At the same time, the heat-exchanged external air enters the first irregular cavity 23 through the air outlet of the air preheater 3 and the connecting pipe 11.

[0038] Preferably, the air outlet of the air preheater 3 is fixedly connected to and communicates with the connecting pipe 11 through the fourth pipe.

[0039] In one possible implementation, the return feeder 6 includes a first return pipe 61, a second return pipe 62, and a third return pipe 63, which are fixedly mounted on and communicate with each other on the frame 1. The first return pipe 61 is fixedly connected to and communicates with the bottom of the cyclone separator 5. A backflush pipe is fixedly mounted on the first return pipe. The third return pipe 63 is fixedly connected to the furnace 2 and communicates with the first shaped cavity 23. The third return pipe 63 is inclined. The cyclone separator 5 separates solid particles and high-temperature flue gas. The high-temperature flue gas continues to float upward and enters the second shaped cavity 24. The solid particles return to the first shaped cavity 23 through the first return pipe 61, the second return pipe 62, and the third return pipe 63 for cyclic combustion.

[0040] Preferably, the external backflushing air enters the first return material pipe 61 through the backflushing pipe to ensure that the solid particles passing through the first return material pipe 61 can be discharged smoothly and to avoid blockage of the first return material pipe 61.

[0041] The embodiments described above are merely preferred embodiments of this utility model and are only used to explain this utility model. They are not intended to limit the scope of implementation of this utility model. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made to the principles and process conditions of this utility model should be included within the scope of the patent application of this utility model.

Claims

1. A circulating fluidized bed boiler, comprising a frame (1) and a furnace (2) fixedly mounted on the frame (1), characterized in that, It also includes an air preheater (3), an igniter (4), a cyclone separator (5), a return feeder (6), and an economizer (7) fixedly mounted on the frame (1). The furnace (2) is equipped with a fluidized bed air distribution plate (21) and a water-cooled structure (8), with the fluidized bed air distribution plate (21) located inside the water-cooled structure (8). The furnace (2) is inclinedly equipped with a feed pipe (22). The air preheater (3) and the igniter (4) are both fixedly connected to and communicate with the furnace (2). The cyclone separator (5) and the return feeder (6) are fixedly connected to and communicate with each other, and both are fixedly connected to and communicate with the furnace (2). The economizer (7) is fixedly connected to and communicates with the furnace (2), the air preheater (3), and the water-cooled structure (8).

2. The circulating fluidized bed boiler according to claim 1, characterized in that, The furnace (2) is provided with a first irregular cavity (23) and a second irregular cavity (24) that are connected. The fluidized bed air distribution plate is located in the first irregular cavity (23). The water-cooled structure (8) is located in the first irregular cavity (23) and the second irregular cavity (24), and the fluidized bed air distribution plate (21) is located inside part of the water-cooled structure (8). The bottom of the feed pipe (22), the air preheater (3), the igniter (4) and the return feeder (6) are all connected to the first irregular cavity (23). The top of the cyclone separator (5) is connected to both the second irregular cavity (24) and the first irregular cavity (23). The air inlet of the economizer (7) is connected to the second irregular cavity (24), and the air outlet of the economizer (7) is connected to the exhaust gas inlet of the air preheater (3).

3. The circulating fluidized bed boiler according to claim 2, characterized in that, The water-cooled structure (8) includes a first membrane water-cooled wall (81), an upper header (82), a lower header (83), a second membrane water-cooled wall (84), an upper boiler drum (85), and a lower boiler drum (86) that are fixedly connected and communicate with each other. The first membrane water-cooled wall (81) is fixedly installed on the inner wall of the first irregular cavity (23), and the fluidized bed air distribution plate (21) is located inside the first membrane water-cooled wall (81). The upper header (82) is fixedly installed on the frame (1). On the furnace (2), the second membrane water-cooled wall (84) is fixedly installed on the inner wall of the second irregular cavity (24), the upper boiler drum (85) and the lower boiler drum (86) are fixedly installed on the furnace (2); the upper header (82) is also fixedly connected to and communicates with the upper boiler drum (85) through a steam pipe (87), the outlet of the economizer (7) is fixedly connected to and communicates with the upper boiler drum (85), and a steam-water separator (9) is fixedly installed on the upper boiler drum (85).

4. The circulating fluidized bed boiler according to claim 3, characterized in that, The first membrane water-cooled wall (81) penetrates the first irregular cavity (23). The top and bottom of the first membrane water-cooled wall (81) are fixedly connected to and communicate with the upper header (82) and the lower header (83) respectively. The upper boiler drum (85) is fixedly connected to and communicates with the lower boiler drum (86) through the second membrane water-cooled wall (84). The lower header (83) is fixedly connected to and communicates with the lower boiler drum (86).

5. The circulating fluidized bed boiler according to claim 4, characterized in that, Multiple upper headers (82) and lower headers (83) are provided. Multiple upper headers (82) and lower headers (83) are fixedly connected to and communicate with the top and bottom of the first membrane water-cooled wall (81), respectively. Some of the upper headers (82) and lower headers (83) are also fixedly connected to the furnace (2). Multiple upper headers (82) are fixedly connected to and communicate with the upper boiler drum (85) through steam pipes (87).

6. The circulating fluidized bed boiler according to claim 3, characterized in that, Two economizers (7) are provided, and the two economizers (7) are fixedly connected and communicate with each other; the air inlet of the upper economizer (7) is connected to the second irregular cavity (24), the air outlet of the lower economizer (7) is connected to the exhaust gas inlet of the air preheater (3), and the water outlet of the upper economizer (7) is fixedly connected and communicates with the upper boiler drum (85).

7. The circulating fluidized bed boiler according to claim 2, characterized in that, The connection points between the feed pipe (22) and the furnace (2), the cyclone separator (5) and the furnace (2), and the return feeder (6) and the furnace (2) are all located above the fluidized bed air distribution plate (21). The connection points between the air preheater (3) and the furnace (2) and the igniter (4) and the furnace (2) are all located below the fluidized bed air distribution plate (21).

8. The circulating fluidized bed boiler according to claim 7, characterized in that, A connecting pipe (11) is fixedly installed on the frame (1). The connecting pipe (11) is fixedly connected to the bottom of the furnace (2) and communicates with the first irregular cavity (23). The connection point between the connecting pipe (11) and the furnace (2) is located below the fluidized bed air distribution plate (21). The air outlets of the igniter (4) and the air preheater (3) are fixedly connected to and communicate with the connecting pipe (11).

9. The circulating fluidized bed boiler according to claim 7, characterized in that, The return feeder (6) includes a first return pipe (61), a second return pipe (62) and a third return pipe (63) fixedly installed on the frame (1) and connected to each other. The first return pipe (61) is fixedly connected to the bottom of the cyclone separator (5) and connected to it. A backflush pipe is fixedly installed on the first return pipe. The third return pipe (63) is fixedly connected to the furnace (2) and connected to the first irregular cavity (23). The third return pipe (63) is inclined.

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