Circulating fluidized bed with low abrasion and stable combustion

Abstract

The invention provides a circulating fluidized bed with low abrasion and stable combustion, and relates to the related field of circulating fluidized beds, the circulating fluidized bed comprises a hearth, a loading frame and a coal briquette crushing mechanism, by arranging the coal briquette crushing mechanism, after coal briquettes are crushed by a coal briquette crusher, the coal briquettes are screened by a screen plate in a screening box firstly, and then the coal briquettes are sieved; screened pulverized coal falls onto a first conveying belt assembly of the adjustable screening assembly, a circulating baffle plate assembly is arranged on the first conveying belt assembly, the pulverized coal conveyed on the first conveying belt assembly is blocked through a circulating baffle plate, and the size of a gap between the circulating baffle plate and the first conveying belt assembly is controlled; the conveying belt assembly is arranged in the hearth and used for blocking pulverized coal particles larger than the gap and pushing the pulverized coal particles leftwards, so that pulverized coal with the needed particle size is conveyed rightwards into a hopper of the pulverized coal feeding machine through the conveying belt assembly, adjusting and screening are conducted according to the pulverized coal with the needed particle size, the pulverized coal with the needed particle size is conveyed according to the working state of the hearth, and the coal particles are fully combusted.

Description

Technical Field

[0001] The invention relates to the field of circulating fluidized beds, in particular to a circulating fluidized bed with low wear and stable combustion. Background Art

[0002] A circulating fluidized bed is a state in which a large number of solid particles are suspended in a moving fluid, so that the particles have certain apparent characteristics of the fluid. This fluid-solid contact state is called a circulating fluidized bed.

[0003] As national environmental protection standards continue to improve, existing and newly built circulating fluidized bed boilers are faced with the problem of further reducing the amount of nitrogen oxides generated in the furnace. In particular, for circulating fluidized bed boilers that burn high-ash, coarse-particle-size, high-volatile, and high-nitrogen content fuels, there is a problem of uneven combustion heat release of the fuel along the height direction of the furnace. The combustion heat release is concentrated in the dense phase area of ​​the furnace, and the heat absorption is weak. A relatively high combustion peak temperature generally appears in the middle and lower parts of the furnace, which increases the generation of thermal nitrogen oxides. According to the working state of the furnace, coal powder of different particle sizes is fed into the furnace or the dense phase area of ​​the furnace. For example, the patent publication No. CN20529949 The Chinese utility model of 7U discloses a circulating fluidized bed fuel coarse and fine grading screening and grading combustion system, comprising a fuel raw material conveying device, a furnace, a secondary air device, and a fuel grading device connected to the fuel raw material conveying device. The fuel grading device is also connected to the furnace and the dense phase area of ​​the furnace respectively. The fuel grading device divides the fuel raw materials conveyed by the fuel raw material conveying device into at least two levels, wherein the coarse coal particles of the first level are conveyed into the dense phase area of ​​the furnace, and the fine coal powder of other levels is conveyed into the furnace by the secondary air device. It is a circulating fluidized bed boiler multi-stage high-efficiency combustion and low-emission combustion system that can reduce the generation of nitrogen oxides and realize efficient combustion of fuel; Although the fuel is classified into different particles through the fuel grading system, the coal powder needs to be crushed before classification. The coal blocks are easy to break when crushed, which is not convenient for controlling the particle size of the coal blocks after crushing. Therefore, screening is required after crushing. Different screens are selected for screening according to the required coal powder particle size. However, the amount of coal powder of different particles cannot be controlled after screening, and since the mesh holes of the screen are fixed, it is not convenient to adjust and screen according to the coal powder particle size required by the furnace, and different screens need to be replaced. Summary of the invention

[0004] In order to solve the above technical problems, the object of the present invention is to provide a circulating fluidized bed with low wear and stable combustion.

[0005] Based on this, the present invention proposes a circulating fluidized bed with low wear and stable combustion, including a furnace, a charging frame and a coal block crushing mechanism, the bottom end of the charging frame is connected with a feeding pipe, and two feeding pipes are provided, the two feeding pipes are respectively connected to the middle part and the bottom of the left end of the furnace, the coal block crushing mechanism is used to crush and screen the coal blocks, the right side of the coal block crushing mechanism is connected to the charging frame, the coal block crushing mechanism includes a coal block crusher, a coal powder feeder, a feeder one, a feeder two, a screening mechanism and a feeder three, the upper Feeder one is used to transport coal blocks to the coal block crusher, and the coal block crusher is used to crush coal blocks. The bottom of the coal block crusher is connected to the material frame of feeder two. Feeder two is used to transport the crushed coal powder to the screening mechanism, and the screening mechanism is used to screen the coal powder. The screening mechanism performs secondary screening on the coal powder through the screen plate and the adjustable screening component. The qualified coal powder after screening is transported to the loading frame through the coal powder feeder, and the unqualified coal powder after screening is transported to the coal block crusher through feeder three for secondary crushing.

[0006] Preferably, a wind chamber is provided at the bottom of the furnace, and the wind chamber is connected to the fan, the top right side of the furnace is connected to the cyclone separator, the bottom end of the cyclone separator is connected to a return pipe, and the other end of the return pipe is connected to the bottom right side of the furnace, the top of the cyclone separator is connected to the exhaust gas flue, the right side of the exhaust gas flue is connected to the dust removal device, and the right side of the dust removal device is connected to the exhaust chimney.

[0007] Preferably, the screening mechanism includes an outer frame, an adjustable screening component, a screening box, a screen plate, a return material frame and a guide plate. The adjustable screening component is installed inside the outer frame, the screening box is fixed to the left side of the top end of the outer frame, the screen plate is installed inside the screening box, the right side of the return material frame is fixedly connected to the outer frame and the screening box, and the bottom end of the return material frame is connected to the hopper of the loader three, the guide plate is fixed to the right side of the bottom of the outer frame, and the bottom end of the guide plate is connected to the hopper of the coal powder loader.

[0008] Preferably, the sieve plate is arranged to be inclined downward from left to right.

[0009] Preferably, the right side of the return material frame is respectively connected with the outer frame and the screening box.

[0010] Preferably, the adjustable screening assembly includes a support frame 1, a conveyor belt assembly 1 and a circulating baffle plate assembly, the support frame 1 is installed with a conveyor belt assembly 1, the conveyor belt assembly 1 is used to convey coal powder, the top of the conveyor belt assembly 1 is provided with a circulating baffle plate assembly, a gap is provided between the bottom of the circulating baffle plate assembly and the conveyor belt assembly 1, the support frame 1 is fixed to the inner bottom of the outer frame, and the circulating baffle plate assembly is fixed to the inner top of the outer frame.

[0011] Preferably, the length of the conveyor belt assembly is greater than the length of the circulating baffle plate assembly, and the circulating baffle plate assembly is arranged on the top right side of the conveyor belt assembly, and the top left side of the conveyor belt assembly is vertically aligned with the screening box.

[0012] Preferably, the circulating material baffle plate assembly includes a support frame 2, a gantry, an electric push rod, a conveyor belt assembly 2 and a circulating baffle, the front and rear sides of the top of the support frame 2 are respectively fixedly connected to the gantry, an electric push rod is installed on the top of the gantry, and the electric push rod is fixed to the top of the outer frame, the conveyor belt assembly 2 is arranged inside the support frame 2, and a circulating baffle is fixed on the outside of the conveyor belt assembly 2, and the bottom of the circulating baffle is arranged with a gap between it and the conveyor belt assembly 1.

[0013] Preferably, the width of the conveyor belt component 2 is consistent with the length of the circulation baffle, and the width of the conveyor belt component 2 is consistent with that of the conveyor belt component 1.

[0014] The present invention has the following advantages: The present invention provides a circulating fluidized bed with low wear and stable combustion through improvement, which has the following improvements compared with the same type of equipment: The present invention provides a circulating fluidized bed with low wear and stable combustion. A coal block crushing mechanism is provided. After the coal blocks are crushed by the coal block crusher, they are first screened by the screen plate in the screening box, and the screened coal powder falls onto the conveyor belt component 1 of the adjustable screening component. A circulating material baffle plate component is provided on the conveyor belt component 1, and the coal powder transported on the conveyor belt component 1 is blocked by the circulating baffle plate. By controlling the size of the gap between the circulating baffle plate and the conveyor belt component 1, coal powder particles larger than the gap are blocked, so that the coal powder with too large particles is screened and blocked, and pushed to the left, so that the coal powder of the required particle size is transported to the right through the conveyor belt component 1 to the hopper of the coal powder feeder, so that the coal powder can be adjusted and screened according to the required particle size, so that the coal powder of the required particle size can be transported according to the working state of the furnace, the coal particles can be fully burned, the generation of coal coke can be reduced, the wear on the boiler can be reduced, and the generation of pollutants such as nitrogen oxides can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the structure of the coal block crushing mechanism of the present invention; Figure 3 It is a schematic diagram of the structure of the screening mechanism of the present invention; Figure 4 This is a schematic diagram of the structure of the adjustable screening component of the present invention; Figure 5 It is a front view of the adjustable screening assembly structure of the present invention; Figure 6 It is a schematic structural diagram of the circulating baffle plate assembly of the present invention.

[0016] Explanation of reference numerals: 1. furnace; 2. charging frame; 3. feeding pipe; 4. coal crushing mechanism; 5. air chamber; 6. fan; 7. cyclone separator; 8. return pipe; 9. tail gas flue; 10. dust removal device; 11. exhaust chimney; 41. coal crusher; 42. coal powder feeder; 43. feeder 1; 44. feeder 2; 45. screening mechanism; 46. feeder 3; 451. external Frame; 452, adjustable screening component; 453, screening box; 454, sieve plate; 455, return frame; 456, guide plate; 4521, support frame one; 4522, conveyor belt component one; 4523, circulation baffle plate component; 45231, support frame two; 45232, gantry; 45233, electric push rod; 45234, conveyor belt component two; 45235, circulation baffle. DETAILED DESCRIPTION

[0017] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0018] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0019] Furthermore, in the description of the present invention, unless otherwise specified, “plurality” means two or more.

[0020] For those skilled in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0022] Please refer to Figure 1-2 The present embodiment provides a circulating fluidized bed with low wear and stable combustion, comprising a furnace 1 and a charging frame 2, wherein a feed pipe 3 is connected to the bottom end of the charging frame 2, and two feed pipes 3 are provided, and the two feed pipes 3 are respectively connected to the middle part and the bottom of the left end of the furnace 1, and gate valves are provided at the left ends of the two feed pipes 3, and the connection between the feed pipe 3 and the charging frame 2 is controlled by the gate valve, thereby controlling the transportation of pulverized coal to the middle part or the dense phase area of ​​the furnace 1; The coal crushing mechanism 4 is used to crush and screen the coal blocks. The right side of the coal crushing mechanism 4 is connected to the loading frame 2. The coal crushing mechanism 4 includes a coal crusher 41, a coal powder feeder 42, a feeder one 43, a feeder two 44, a screening mechanism 45 and a feeder three 46. The feeder one 43 is used to transport the coal blocks to the coal crusher 41. The coal crusher 41 is used to crush the coal blocks. The bottom of the coal crusher 41 is connected to the material frame of the feeder two 44. The feeder two 44 is used to transport the crushed coal powder to the screening mechanism 45. The screening mechanism 45 is used to screen the coal powder. The screening mechanism 45 performs secondary screening on the coal powder through the sieve plate 454 and the adjustable screening component 452. The qualified coal powder after screening is transported to the loading frame 2 through the coal powder feeder 42, and the unqualified coal powder after screening is transported to the coal crusher 41 through the feeder three 46 for secondary crushing.

[0023] The furnace 1 is provided with a detection device, which detects the working characteristics of the furnace 1, so as to add coal powder of required particle size according to the detection characteristics of the furnace 1. The Chinese invention patent with the publication number CN108460508B discloses an online energy-saving monitoring method based on the working characteristics of the circulating fluidized bed boiler. By establishing an overall mathematical model of the circulating fluidized bed boiler, the established overall mathematical model of the circulating fluidized bed is used to calculate the operating parameter values. The operating parameters include the temperature parameters in the furnace, the inlet and outlet temperature parameters of each heat exchanger of the flue at the tail end of the furnace, and the pressure parameters in the furnace; refined monitoring of the furnace can be achieved; The detection equipment uses the above patented detection technology to detect the working status of the furnace 1.

[0024] The coal powder feeder 42, the feeder one 43, the feeder two 44 and the feeder three 46 all adopt the model ‌‌, which has a good feeding effect on particles and powders and is suitable for feeding coal block particles and coal powder.

[0025] The coal block crushing mechanism 4 adopts a PE600 type coal crusher, which is suitable for crushing materials such as coal and ore, and has a good crushing effect on coal.

[0026] A wind chamber 5 is provided at the bottom of the furnace 1, and the wind chamber 5 is connected to the fan 6. The top right side of the furnace 1 is connected to the cyclone separator 7. The bottom end of the cyclone separator 7 is connected to a return pipe 8, and the other end of the return pipe 8 is connected to the bottom right side of the furnace 1. The top of the cyclone separator 7 is connected to the exhaust gas flue 9. The right side of the exhaust gas flue 9 is connected to the dust removal device 10. The right side of the dust removal device 10 is connected to the exhaust chimney 11.

[0027] Please refer to Figure 3 The screening mechanism 45 includes an outer frame 451, an adjustable screening component 452, a screening box 453, a sieve plate 454, a return material frame 455 and a guide plate 456. The adjustable screening component 452 is arranged inside the outer frame 451, the screening box 453 is fixed to the left side of the top of the outer frame 451, the sieve plate 454 is installed inside the screening box 453, the right side of the return material frame 455 is fixedly connected to the outer frame 451 and the screening box 453, and the bottom end of the return material frame 455 is connected to the hopper of the feeder 46, and the guide plate 456 is fixed to the right side of the bottom of the outer frame 451, and the bottom end of the guide plate 456 is connected to the hopper of the coal powder feeder 42.

[0028] The sieve plate 454 is tilted downward from left to right. The sieve plate 454 can be set in multiple layers to perform multi-layer screening of the coal powder, thereby increasing the screening effect of the coal powder. The falling coal powder is guided to the right side of the sieve plate 454 by the guide plate between the sieve plates 454, which is conducive to the coal powder sliding from right to left on the sieve plate 454 for screening. The right side of the return frame 455 is respectively connected with the outer frame 451 and the screening box 453, so that the crushed coal powder is screened through the screen in the sieve plate 454, and the coal powder with larger particles is at the top of the sieve plate 454, guided by the sieve plate 454 to slide into the inside of the return frame 455, and falls into the hopper of the feeder three 46 through the return frame 455.

[0029] Please refer to Figure 4-5 The adjustable screening component 452 includes a support frame 4521, a conveyor belt component 4522 and a circulating baffle plate component 4523. The conveyor belt component 4522 is installed inside the support frame 4521. The conveyor belt component 4522 is used to convey coal powder. The top of the conveyor belt component 4522 is provided with a circulating baffle plate component 4523. A gap is provided between the bottom of the circulating baffle plate component 4523 and the conveyor belt component 4522. The support frame 4521 is fixed to the inner bottom of the outer frame 451, and the circulating baffle plate component 4523 is fixed to the inner top of the outer frame 451.

[0030] The length of the conveyor belt assembly 4522 is greater than the length of the circulating baffle plate assembly 4523, and the circulating baffle plate assembly 4523 is arranged on the top right side of the conveyor belt assembly 4522, and the top left side of the conveyor belt assembly 4522 is vertically aligned with the bottom discharge end of the screening box 453, and the coal powder screened by the screen plate 454 in the screening box 453 falls to the top left side of the conveyor belt assembly 4522, and the coal powder is transported to the right through the conveyor belt assembly 4522.

[0031] Please refer to Figure 6 The circulating material baffle plate assembly 4523 comprises a supporting frame 2 45231, a gantry 45232, an electric push rod 45233, a conveyor belt assembly 2 45234 and a circulating baffle 45235. The front and rear sides of the top of the supporting frame 2 45231 are respectively fixedly connected to the gantry 45232. The top of the gantry 45232 is equipped with an electric push rod 45233, which is fixed to the top of the outer frame 451. The conveyor belt assembly 2 45234 is arranged inside the supporting frame 45231. The outer side of the conveyor belt assembly 2 45234 is fixed with a circulating baffle 45235. The circulating baffles 45235 are equidistantly arranged on the surface of the conveyor belt assembly 2 45234, and the spacing between the circulating baffles 45235 is greater than twenty centimeters. The bottom of the circulating baffle 45235 is arranged with a gap with the conveyor belt assembly 1 4522.

[0032] The electric linear actuator 45233 uses the HTW1000 electric linear actuator, which is suitable for industrial large-load scenarios and has strong supporting force. The width of conveyor belt component 2 45234 is consistent with the length of the circulating baffle 45235, and the width of conveyor belt component 2 45234 is consistent with that of conveyor belt component 1 4522. The coal powder transported on conveyor belt component 1 4522 is blocked by the circulating baffle 45235, and the coal powder particles larger than the gap are blocked by controlling the size of the gap between the circulating baffle 45235 and conveyor belt component 1 4522, so that the coal powder with too large particles can be screened and blocked, and pushed to the left, so that the coal powder of the required particle size is transported to the right through conveyor belt component 2 45234 to the hopper of the coal powder loader 42.

[0033] The conveyor belt assembly 1 4522 and the conveyor belt assembly 2 45234 are both composed of a conveyor belt, a support roller and a driving motor. The conveyor belt assembly 1 4522 conveys the coal powder through the conveyor belt, and the conveyor belt assembly 2 45234 drives the circulating baffle 45235 to move in a circulation manner through the rotation of the conveyor belt.

[0034] The present invention provides a circulating fluidized bed with low wear and stable combustion through improvement, and its working principle is as follows; 1. The coal blocks are transported to the coal crusher 41 through the feeder 1 43 for crushing. After being crushed by the coal crusher 41, the coal blocks fall into the hopper of the feeder 2 44. The crushed coal powder is transported to the upper part of the screening box 453 through the feeder 2 44. The coal powder is screened for the first time through the screen plate 454 in the screening box 453 to screen out coal powder with a particle size close to the required particle size. The screened coal powder falls onto the conveyor belt assembly 1 4522 of the adjustable screening assembly 452, and the coal powder particles with larger particles are introduced into the hopper of the feeder 3 46 through the return frame 455; 2. According to the required coal powder particle size, the gap between the circulating baffle 45235 of the circulating baffle plate assembly 4523 and the conveyor belt assembly 1 4522 is controlled, and the height of the supporting frame 2 45231, the gantry 45232, the conveyor belt assembly 2 45234 and the circulating baffle 45235 is adjusted by controlling the extension and contraction of the electric push rod 45233, thereby adjusting the gap between the circulating baffle 45235 and the conveyor belt assembly 1 4522; 3. The conveyor belt of the conveyor belt assembly 1 4522 is rotated to drive the coal powder to be transported to the right, and the conveyor belt of the conveyor belt assembly 2 45234 is controlled to rotate to drive the circulation baffle 45235 to rotate, and the circulation baffle 45235 moves to the left when it is located at the bottom of the conveyor belt, and the coal powder particles larger than the gap are blocked by the circulation baffle 45235, so that the coal powder with too large particles can be screened and blocked, and pushed to the left, so that the coal powder of the required particle size is transported to the right through the conveyor belt assembly 1 4522 to the hopper of the coal powder feeder 42, and the coal powder can be adjusted and screened according to the required particle size. Since the feeder 1 43 quantitatively transports coal blocks to the coal block crusher 41 each time, the coal blocks fall into the feeder 2 44 after being crushed, and the feed The coal powder is sent to the screening box 453, and the coal powder is screened by the screening box 453 and falls onto the conveyor belt assembly 4522. When the feeder 43 is feeding the next coal block, the coal powder screened by the screening box 453 falls with a certain time gap, and because the conveyor belt assembly 4522 continuously conveys the coal powder to the right, the screening of the coal powder is completed during this time gap, and the large-particle coal powder on the top of the conveyor belt assembly 4522 is conveyed to the left through the circulation baffle 45235 by controlling the coal powder conveyor belt assembly 4522, so that the large-particle coal powder is conveyed to the left and introduced into the hopper of the feeder 46 through the return frame 455, so as to avoid the continuous accumulation of large-particle coal powder on the conveyor belt assembly 4522, which affects the screening effect of the coal powder; Fourth, the pulverized coal is transported to the charging frame 2 by the pulverized coal feeder 42, and the pulverized coal is added into the furnace 1 or into the dense phase area of ​​the furnace 1 according to the position where the pulverized coal is added required by the furnace 1; Fifth, air is blown into the wind chamber 5 by the fan 6, and the wind in the wind chamber 5 is blown into the bottom of the furnace 1, and fluidization is performed when the gas velocity is greater than the free settling velocity of the particles. The particles are carried out to the cyclone separator 7 by the airflow, and after the gas and solid are separated by the cyclone separator 7, the solid is circulated back to the furnace 1, and the gas enters the dust removal device 10 through the exhaust flue 9 for dust removal, and is finally discharged through the exhaust chimney 11.

[0035] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. Claims A circulating fluidized bed with low wear and stable combustion, comprising a furnace (1) and a charging frame (2), wherein the bottom end of the charging frame (2) is connected to a feed pipe (3), and two feed pipes (3) are provided, and the two feed pipes (3) are respectively connected to the middle of the left end and the bottom of the furnace (1); It is characterized in that The machine also includes a coal crushing mechanism (4), the coal crushing mechanism (4) being used to crush and screen coal blocks. The right side of the coal crushing mechanism (4) is connected to the charging frame (2). The coal crushing mechanism (4) includes a coal crusher (41), a coal powder feeder (42), a first feeder (43), a second feeder (44), a screening mechanism (45) and a third feeder (46). The first feeder (43) is used to transport coal blocks to the coal crusher (41). The coal crusher (41) is used to crush coal blocks. The bottom of the pulverizer (41) is connected to the material frame of the second loader (44). The second loader (44) is used to convey the pulverized coal powder to the screening mechanism (45). The screening mechanism (45) is used to screen the coal powder. The screening mechanism (45) performs secondary screening on the coal powder through the screen plate (454) and the adjustable screening component (452). The qualified coal powder after screening is conveyed to the charging frame (2) through the coal powder loader (42), and the unqualified coal powder after screening is conveyed to the coal block pulverizer (41) through the third loader (46) for secondary pulverization.

2. A circulating fluidized bed with low wear and stable combustion according to claim 1, characterized in that: A wind chamber (5) is provided at the bottom of the furnace (1), and the wind chamber (5) is connected to a fan (6); the top of the right side of the furnace (1) is connected to a cyclone separator (7); the bottom end of the cyclone separator (7) is connected to a return pipe (8), and the other end of the return pipe (8) is connected to the bottom of the right side of the furnace (1); the top of the cyclone separator (7) is connected to an exhaust gas flue (9); the right side of the exhaust gas flue (9) is connected to a dust removal device (10), and the right side of the dust removal device (10) is connected to an exhaust chimney (11).

3. A circulating fluidized bed with low wear and stable combustion according to claim 1, characterized in that: The screening mechanism (45) comprises an outer frame (451), an adjustable screening component (452), a screening box (453), a screen plate (454), a return material frame (455) and a guide plate (456); the outer frame (451) is provided with an adjustable screening component (452); the screening box (453) is fixed to the left side of the top end of the outer frame (451); the screen plate (454) is installed inside the screening box (453); the right side of the return material frame (455) is fixedly connected to the outer frame (451) and the screening box (453); the bottom end of the return material frame (455) is connected to the hopper of the third feeder (46); the guide plate (456) is fixed to the right side of the bottom of the outer frame (451); and the bottom end of the guide plate (456) is connected to the hopper of the coal powder feeder (42).

4. A circulating fluidized bed with low wear and stable combustion according to claim 3, characterized in that: The sieve plate (454) is arranged to be inclined downward from left to right.

5. A circulating fluidized bed with low wear and stable combustion according to claim 3, characterized in that: The right side of the material return frame (455) is respectively connected to the outer frame (451) and the screening box (453).

6. A circulating fluidized bed with low wear and stable combustion according to claim 3, characterized in that: The adjustable screening component (452) comprises a support frame (4521), a conveyor belt component (4522) and a circulating material baffle plate component (4523); the support frame (4521) is internally installed with a conveyor belt component (4522); the conveyor belt component (4522) is used to convey coal powder; the top of the conveyor belt component (4522) is provided with a circulating material baffle plate component (4523); a gap is provided between the bottom of the circulating material baffle plate component (4523) and the conveyor belt component (4522); the support frame (4521) is fixed to the inner bottom of the outer frame (451); and the circulating material baffle plate component (4523) is fixed to the inner top of the outer frame (451).

7. A circulating fluidized bed with low wear and stable combustion according to claim 6, characterized in that: The length of the conveyor belt component 1 (4522) is greater than the length of the circulating material baffle plate component (4523), and the circulating material baffle plate component (4523) is arranged on the top right side of the conveyor belt component 1 (4522), and the top left side of the conveyor belt component 1 (4522) is vertically aligned with the screening box (453).

8. A circulating fluidized bed with low wear and stable combustion according to claim 6, characterized in that: The circulating material baffle plate assembly (4523) comprises a second support frame (45231), a gantry (45232), an electric push rod (45233), a second conveyor belt assembly (45234) and a circulating baffle (45235); the front and rear sides of the top of the second support frame (45231) are respectively fixedly connected to the gantry (45232); the top of the gantry (45232) is equipped with an electric push rod (45233); the electric push rod (45233) is fixed to the top of the outer frame (451); the interior of the second support frame (45231) is provided with a second conveyor belt assembly (45234); the outer side of the second conveyor belt assembly (45234) is fixed with a circulating baffle (45235); the bottom of the circulating baffle (45235) is provided with a gap with the first conveyor belt assembly (4522).

9. A circulating fluidized bed with low wear and stable combustion according to claim 8, characterized in that: The width of the conveyor belt component 2 (45234) is consistent with the length of the circulation baffle (45235), and the width of the conveyor belt component 2 (45234) is consistent with that of the conveyor belt component 1 (4522).

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