Fluoroplastic steel air preheater for multi-source tail gas boiler

Abstract

The invention discloses a fluoroplastic steel air preheater for a multi-source tail gas boiler. The fluoroplastic steel air preheater comprises a shell, two heat exchange assemblies arranged in the shell, a pair of supporting plates corresponding to the two heat exchange assemblies and a cleaning device. Two ends of the shell in the length direction are communicated; each heat exchange assembly comprises a plurality of heat exchange pipes, and the ends of the heat exchange pipes penetrate through and extend out of the two sides of the shell in the width direction. The cleaning device comprises a pair of base frames arranged at the two ends of the heat exchange tube, a pair of transmission assemblies, a pair of supporting assemblies and a plurality of cleaning assemblies. The bottom of the base frame extends towards the shell and is fixedly connected with the bottom of the shell. The transmission assemblies are installed in the base frame, the cleaning assemblies are used for moving in the heat exchange tubes to remove dust, the two ends of each cleaning assembly are fixedly connected with traction ropes, and the traction ropes are fixedly connected with the corresponding transmission assemblies so that the transmission assemblies can rotate to drive the traction ropes and the cleaning assemblies to move; the supporting assembly is arranged outside the end of the heat exchange pipe and used for supporting the cleaning assembly moving out of the heat exchange pipe.

Description

Technical Field

[0001] This invention relates to the field of air preheater cleaning technology, specifically to a fluoroplastic steel air preheater for multi-source exhaust gas boilers. Background Technology

[0002] An air preheater is a heat exchange surface in the boiler's tail flue that preheats the air entering the boiler to a certain temperature through internal heat exchange fins. It is a device used to improve the boiler's heat exchange performance and reduce energy consumption. In some special environments, it is difficult to continuously supply a single type of flue gas. The flue gas composition is relatively complex, such as containing high sulfur, high humidity, or high ammonia. If the accumulated ash is not cleaned in time, it is easy to form hard scale, which affects the heat exchange performance. Conventional ash cleaning is time-consuming and increases economic costs.

[0003] CN222143122U discloses an anti-clogging device for a horizontal tubular air preheater, which mainly uses a crossbar to drive a cleaning block into the heat exchange tube for cleaning. This design determines the length of the heat exchange tube, requiring the crossbar to be of a corresponding length, resulting in significant space waste. Furthermore, large areas of hard scale may prevent the cleaning block from moving. Therefore, this invention provides a fluoroplastic steel air preheater for multi-source exhaust gas boilers. Summary of the Invention

[0004] The purpose of this invention is to provide a fluoroplastic steel air preheater for multi-source exhaust gas boilers to solve the problem of inconvenient ash removal mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: A fluoroplastic steel air preheater for a multi-source exhaust gas boiler includes a shell, two sets of heat exchange components disposed within the shell, a pair of support plates corresponding to the two sets of heat exchange components, and a cleaning device; the two ends of the shell are connected in the length direction; each set of heat exchange components includes multiple heat exchange tubes, the ends of which penetrate through and extend out to both sides in the width direction of the shell; the heat exchange tubes of each set of heat exchange components penetrate through the corresponding support plate; The cleaning device includes a pair of base frames disposed at both ends of the heat exchange tubes, a pair of transmission components, a pair of support components, and multiple cleaning components. The bottom of the base frames extends toward the shell and is fixedly connected to the bottom of the shell. The transmission components are installed inside the base frames. The cleaning components are used to move inside the heat exchange tubes to clean dust. Both ends of the cleaning components are fixedly connected to traction ropes, which are fixedly connected to the corresponding transmission components so that the traction ropes and cleaning components can be moved by rotating the transmission components. The support components are disposed outside the ends of the heat exchange tubes and are used to support the cleaning components that move out of the heat exchange tubes, so that the cleaning components remain coaxial with the heat exchange tubes.

[0006] Preferably, the transmission assembly includes multiple spaced rotating rods, multiple take-up shafts, multiple gears, and at least one motor; the two ends of the rotating rods are rotatably connected to the vertical sides of the base frame; multiple spaced take-up shafts are fixedly connected to each rotating rod; gears are meshed between adjacent rotating rods; and the motor drive shaft is fixedly connected to the rotating rod.

[0007] Preferably, the spacing between the rotating rods is the same as the spacing between adjacent heat exchange tubes arranged vertically, the spacing between the take-up spools is the same as the spacing between adjacent heat exchange tubes arranged horizontally, and the take-up spools are fixedly connected to the end of the traction rope.

[0008] Preferably, the support assembly includes a limiting ring with an internal air passage, an air outlet ring, multiple horizontal pipes, and multiple vertical pipes; the air outlet ring is fixedly connected to the outer wall of the limiting ring; each air outlet ring has multiple air outlet rods with internal cavities fixedly connected to its end away from the heat exchange tube, so as to communicate with the air passage; horizontal pipes are fixedly connected between adjacent air outlet rings; vertical pipes are fixedly connected between adjacent horizontal pipes, and the bottommost vertical pipe extends downward and is fixedly connected to the bottom of the base frame.

[0009] Preferably, the end of the air outlet rod away from the heat exchange tube is bent, and an air outlet facing the heat exchange tube is opened at the bend; the inner diameter of the limiting ring is the same as the inner diameter of the heat exchange tube.

[0010] Preferably, the cleaning assembly includes a cleaning ring and a pair of support rings. The inner wall of the cleaning ring extends further in the middle to increase the wall thickness, and the two ends of the further extended portion are inclined to form an angle with the inner walls at both ends of the cleaning ring. One end of the pair of support rings is fixedly connected to the two ends of the further extended portion, so that an angled region is formed between the outer wall of the support ring and the inner wall of the end of the cleaning ring.

[0011] Preferably, the included angle area is set as the storage area, and the storage area corresponds to the air outlet of the air outlet rod; the outer wall of the other end of the pair of support rings is bent outward to form a limiting part; the cleaning ring is made of flexible material.

[0012] Preferably, the cleaning assembly further includes a pair of support rods, which are disposed inside the cleaning ring and are arranged crosswise, with their ends respectively fixedly connected to the inner walls of the pair of support rings.

[0013] Preferably, each support ring has an internal clearance cavity, and the clearance cavity also has a clearance component; the clearance component includes a spring, a connecting ring, and multiple clearance ropes; the connecting ring is fixedly connected to the end of the spring away from the limiting part, one end of each clearance rope is fixedly connected to the inner wall of the end of the cleaning ring, and the other end passes through the support ring and is fixedly connected to the connecting ring; the end of the traction rope is divided into multiple ends, each end extending into the clearance cavity and fixedly connected to the connecting ring.

[0014] Preferably, the avoidance rope is elastic; the elastic force required for the spring to be fully compressed is greater than the force required to move the cleaning ring and the support ring, and the force required for the spring to move the cleaning ring and the support ring is less than the force required for the cleaning ring to deform itself.

[0015] Compared with the prior art, the beneficial effects of the present invention are: It has high dust removal efficiency and can achieve routine cleaning; the cleaning component moves back and forth inside the heat exchange tube under the drive of the traction rope, which can scrape off the dust adhering to the tube wall in time, and prevent it from accumulating for a long time and reacting with complex flue gas components to form hard scale.

[0016] Adaptive cleaning enhances cleaning reliability. The cleaning ring features a flexible material design and an obstacle avoidance mechanism consisting of a spring and an obstacle avoidance rope. When encountering hard, unscratch-like scale inside the tube, the spring compresses, causing the cleaning ring's end to elastically deform and "jump over" the scale, then automatically resumes cleaning. This avoids the risk of jamming or damage during cleaning; it also improves the heat exchange performance of heat exchange tubes with hard scale and prevents further scale buildup. Accumulated dust in the storage area is blown out by the exhaust fan, ensuring more thorough cleaning.

[0017] By improving space utilization and using a traction rope to move the cleaning components, the space occupied is greatly reduced, making it adaptable to more working environments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a schematic diagram of the disassembled structure of the housing and fixing frame of the present invention; Figure 3 This is a schematic diagram of the connection between the cleaning device and the housing of the present invention; Figure 4 This is a front view of the connection between the cleaning device and the housing of the present invention; Figure 5 This is a front view of the connection between the transmission component and the base frame of the present invention; Figure 6 This is a front view of the connection between the support component and the cleaning component 44 of the present invention; Figure 7 This is a schematic diagram of the connection between the heat exchange tube and the cleaning component of the present invention; Figure 8 This is a schematic diagram of the connection between the cleaning component and the support component of the present invention; Figure 9 This is a cross-sectional view of the connection between the heat exchange tube and the cleaning component of the present invention; Figure 10 For the present invention Figure 9 Cross-sectional view of the connection between the cleaning component and the support component at point A in the middle; Figure 11 For the present invention Figure 9 Cross-sectional view showing the positional relationship between the support assembly and the heat exchange tube at point B; Figure 12 This is a cross-sectional view of the connection between the cleaning ring and the limiting ring of the present invention; Figure 13 For the present invention Figure 12 Cross-sectional view of the avoidance component at point C; Figure 14 This is an anatomical diagram of the cleaning ring, limiting ring, and air outlet ring of the present invention. Figure 15 This is a schematic diagram of the connection between the cleaning ring and the support ring of the present invention.

[0019] In the diagram: 1. Shell 1, 11. Fixing frame 1, 2. Heat exchange assembly 2, 21. Heat exchange tube 2, 3. Support plate 3, 4. Cleaning device 4, 41. Base frame 4, 42. Transmission assembly 42, 421. Rotating rod 422. Take-up shaft 422. Gear 423. Motor 424. Support assembly 43. Limiting ring 431. Air outlet ring 432. Air outlet rod 4321. Horizontal pipe 433. Vertical pipe 434. Cleaning assembly 44. Cleaning ring 441. Support ring 442. Limiting part 4421. Avoidance cavity 4422. Guide ring 4423. Support rod 443. Storage area 444. Traction rope 45. Avoidance assembly 46. Spring 461. Connecting ring 462. Avoidance rope 463. Detailed Implementation

[0020] Example 1: Please see Figures 1-15 The present invention provides a technical solution: such as Figures 1-4 As shown, a fluoroplastic steel air preheater for a multi-source exhaust gas boiler includes a shell 1, two sets of heat exchange components 2, a pair of support plates 3 corresponding to the two sets of heat exchange components 2, and a cleaning device 4. The two ends of the shell 1 are connected along its length. The two sets of heat exchange components 2 are arranged inside the shell 1. Each set of heat exchange components 2 includes multiple heat exchange tubes 21, which are arranged along the width of the shell 1 and have their ends extending through and out to both sides of the shell 1 in the width direction. Each support plate 3 is located in the middle of each set of heat exchange components 2. The support plate 3 has multiple through holes corresponding to the outer diameter of the heat exchange tubes 21 for the heat exchange tubes 21 of each set of heat exchange components to pass through, thereby improving the stability of the heat exchange components 2. Fixing frames 11 are also fixedly connected to both sides of the shell 1 in the width direction to surround the ends of the heat exchange tubes 21 extending from both sides within the fixing frames 11. The heat exchange tube 21 is a fluoroplastic steel heat exchange tube 21. The fluoroplastic steel heat exchange tube 21 has advantages such as corrosion resistance, scale and ash resistance, temperature and pressure resistance, low resistance and long service life. It can be used in complex environments and can adapt to complex flue gas composition (such as high sulfur, high humidity and high ammonia, etc.) to avoid ash and scale accumulation on the inner wall of the tube.

[0021] like Figures 5-7As shown, the cleaning device 4 includes a pair of base frames 41 disposed at both ends of the heat exchange tube 21, a pair of transmission assemblies 42, a pair of support assemblies 43, and multiple cleaning assemblies 44. The base frames 41 have a rectangular cross-section, extending towards the bottom of the housing 1 and fixedly connected to the bottom of the housing 1. The transmission assemblies 42 are installed inside the base frames 41. The cleaning assemblies 44 are used to move inside the heat exchange tube 21 to remove dust accumulated on the inner wall of the heat exchange tube 21. Both ends of the cleaning assemblies 44 are fixedly connected to traction ropes 45, which are fixedly connected to the corresponding transmission assemblies 42, so that the traction ropes 45 and the cleaning assemblies 44 can be moved by the rotation of the transmission assemblies 42. The support assemblies 43 are disposed outside the ends of the heat exchange tube 21 and are used to support the cleaning assemblies 44 that have moved out of the heat exchange tube 21, so that the cleaning assemblies 44 remain coaxial with the heat exchange tube 21.

[0022] like Figures 8-11 As shown, the transmission assembly 42 includes multiple rotating rods 421, multiple take-up shafts 422, multiple gears 423, and at least one motor 424. The multiple rotating rods 421 are spaced apart, with their ends rotatably connected to the vertical sides of the base frame 41, and the spacing between the rotating rods 421 is the same as the spacing between adjacent vertically arranged heat exchange tubes 21. Multiple spaced take-up shafts 422 are fixedly connected to each rotating rod 421, with the spacing being the same as the spacing between adjacent horizontally arranged heat exchange tubes 21. The take-up shafts 422 are fixedly connected to the ends of the traction rope 45, and the traction rope 45 is retracted or released by rotating the take-up shafts 422. Gears 423 are disposed between adjacent rotating rods 421 and mesh with adjacent rotating rods 421, and gears 423 are also rotatably connected to the inner wall of any vertical side of the base frame 41. The motor 424 is mounted on the outer wall of any vertical side of the base frame 41, and the drive shaft passes through the base frame 41 and is fixedly connected to the rotating rod 421 so as to drive multiple rotating rods 421 and gears 423 to rotate synchronously in the same direction.

[0023] The support assembly 43 includes a limiting ring 431, an air outlet ring 432, multiple horizontal pipes 433, and multiple vertical pipes 434. The air outlet ring 432 is fixedly connected to the outer wall of the end of the limiting ring 432 away from the heat exchange tube 21, and the inner diameter of the limiting ring 431 is the same as the inner diameter of the heat exchange tube 21. The end of the limiting ring 431 near the heat exchange tube 21 is funnel-shaped to facilitate the movement of the cleaning assembly 44 into the limiting ring 431. Each air outlet ring 432 is fixedly connected to multiple air outlet rods 4321 with internal cavities at its end away from the heat exchange tube 21. Each air outlet ring 431 has an air passage inside to communicate with the cavity inside the air outlet rod 4321. The end of the air outlet rod 4321 away from the heat exchange tube 21 is bent, and an air outlet facing the heat exchange tube 21 is opened at the bend. Horizontally, horizontal pipes 433 are fixedly connected between adjacent air outlet rings 432; vertically, vertical pipes 434 are fixedly connected between adjacent horizontal pipes 433, so that the horizontal pipes 433, vertical pipes 434 and air outlet rings 432 are interconnected. The bottommost vertical pipe 434 extends downward and is fixedly connected to the bottom of the base frame 41; any vertical pipe 434 is connected to an air supply device (not shown in the figure), such as an air pump, which supplies gas to the horizontal pipes 433, vertical pipes 434 and air outlet rings 432, and finally outputs it from the air outlet of the air outlet rod 4321.

[0024] like Figures 12-15 As shown, the cleaning assembly 44 includes a cleaning ring 441, a pair of support rings 442, and a pair of support rods 443. The inner wall of the cleaning ring 441 extends further to increase the wall thickness, and the two ends of the extended portion are inclined to form an angle with the inner walls at both ends of the cleaning ring 441. One end of the pair of support rings 442 is fixedly connected to the two ends of the extended portion, so that an angled area is formed between the outer wall of the support rings 442 and the inner wall at the end of the cleaning ring 441. The outer wall of the other end of the pair of support rings 442 is bent outward to form a limiting portion 4421, and the angled area is set as a storage area 444. The storage area 444 corresponds to the air outlet opened on the air outlet rod 4321. By moving the cleaning ring 441, the accumulated dust on the inner wall of the heat exchange tube 21 can be scraped off and fall to the limiting part 4421. Guided by the limiting part 4421, the accumulated dust slides to the bottom of the heat exchange tube 21. As the cleaning ring 441 moves, the accumulated dust that has slid to the bottom of the heat exchange tube 21 is pushed into the storage area 444 at the bottom. The cleaning ring 441 is made of a material with a certain degree of flexibility, such as rubber, and the support ring 442 is made of metal. A pair of support rods 443 are set inside the cleaning ring 441 and are arranged crosswise, with their ends fixedly connected to the inner walls of the pair of support rings 442 to improve the stability of the support rings 442.

[0025] Each support ring 442 has a clearance cavity 4422 inside, and a clearance assembly 46 is also provided inside the clearance cavity 4422. The clearance assembly 46 includes a spring 461, a connecting ring 462, and multiple clearance ropes 463. The connecting ring 462 is fixedly connected to the end of the spring 461 away from the limiting part 4421. One end of each clearance rope 463 is fixedly connected to the inner wall of the end of the cleaning ring 441, and the other end passes through the support ring 442 and is fixedly connected to the connecting ring 462. The end of the traction rope 45 is divided into multiple ends, each end extending into the clearance cavity 4422, passing through the inside of the spring 461, and fixedly connected to the connecting ring 462.

[0026] The avoidance rope 463 has a certain degree of elasticity; the elastic force required for the spring 461 to be fully compressed is greater than the force required to move the cleaning ring 441 and the support ring 442, and the force required for the spring 461 to move the cleaning ring 441 and the support ring 442 is less than the force required for the cleaning ring 441 to deform itself. The spring 461 is pulled by the movement of the traction rope 45, causing the spring 461 to be partially compressed, which in turn moves the support ring 442 and the cleaning ring 441. At this time, the cleaning ring 441 itself will not deform. One and a pair of guide rings 4423 are fixedly connected to the inner wall of the avoidance cavity 4422 and the outer wall of the support ring 442, respectively, for the avoidance rope 463 to pass through.

[0027] Working principle: Figure 5 Taking the location of the cleaning component 44 as an example, the current position of the cleaning component 44 is defined as the right side, and the other side is defined as the left side. When cleaning is required (the frequency of cleaning can be determined by the operator; if the flue gas components are prone to scaling, the cleaning frequency can be increased, and vice versa, the frequency can be reduced to delay the scaling time or even avoid the structure), the operator starts a pair of motors 424. Each motor 424 drives the corresponding rotating rod 421, take-up shaft 422 and gear 423 to rotate synchronously in the same direction. The left take-up shaft 422 rotates to gradually retract the left traction rope 45. The movement of the traction rope 45 drives the cleaning component 44 from the right side into the heat exchange tube 21 and moves inside the heat exchange tube 21 until it moves out from the left side of the heat exchange tube 21. At the same time, the right take-up shaft 422 rotates to wind out the traction rope 45 and moves with the cleaning component 44. After the cleaning component 44 is removed from the heat exchange tube 21, the operator turns off the motor 424 and then turns on the gas supply equipment to deliver the gas through the horizontal pipe 433, the vertical pipe 434 and the air outlet ring 432 until it is delivered to the air outlet rod 4321. Finally, the gas is blown out from the air outlet of the air outlet rod 4321 and blown towards the storage area 444 to blow out the accumulated dust in the storage area 444.

[0028] When the take-up spool 422 on the left side starts to rotate, the left traction rope 45 will be gradually taken up. As the left traction rope 45 is taken up, the left spring 461 will be gradually pulled, causing the spring 461 to be compressed. During the compression process, the spring 461 will pull the avoidance rope 463. Since the avoidance rope 463 is elastic, the avoidance rope 463 will be stretched, but the end of the cleaning ring 441 will not deform. Until the force required to compress the spring 461 is greater than the force required for the cleaning ring 441 and the support ring 442 to move, the cleaning ring 441 and the support ring 442 will begin to move and enter the heat exchange tube 21. As the cleaning ring 441 moves within the heat exchange tube 21, the left end of the cleaning ring 441 scrapes away the accumulated dust on the inner wall of the heat exchange tube 21. The dust falls to the limiting part 4421 and slides down to the bottom of the heat exchange tube 21 under the guidance of the limiting part 4421. As the cleaning ring 441 continues to move, it pushes the dust that has slid to the bottom of the heat exchange tube 21 into the storage area 444 at the bottom, until the cleaning ring 441 is removed from the left end of the heat exchange tube 21. After the cleaning ring 441 is removed, the air delivered through the air outlet of the air outlet rod 4321 blows the dust out of the storage area 444.

[0029] If hard scale is present inside the heat exchange tube 21, the movement process of the cleaning ring 441 within the heat exchange tube 21 is as follows: When the left end of the cleaning ring 441 encounters hard scale during its movement, the cleaning ring 441 temporarily stops moving. At this time, the left take-up spool 422 continues to rotate, which will cause the left traction rope 45 to further compress the spring 461. The compression of the spring 461 will cause the avoidance rope 463 to further lengthen. When the force exerted by the traction rope 45 on the compression spring 461 is greater than the force required for the cleaning ring 441 to deform, The cleaning ring 441 deforms under the pull of the avoidance rope 463, and the left end of the cleaning ring 441 retracts towards the center of the end of the cleaning ring 441, so that the end of the cleaning ring 441 avoids the hard scale. Since the cleaning ring 441 is made of flexible material, the outer wall of the cleaning ring 441 will be compressed when passing through the hard scale, so that the cleaning ring 441 can continue to move. Then, during the movement, the spring 461 gradually returns to the state when the cleaning ring 441 is cleaning the dust, and the end of the cleaning ring 441 gradually resets until it is removed from the heat exchange tube 21.

Claims

1. A fluoroplastic steel air preheater for multi-source exhaust gas boilers, characterized in that: The utility model provides a heat exchange device and cleaning device, including shell (1), two groups of heat exchange components (2) are arranged in shell (1), a pair of support plate (3) and cleaning device (4) correspond to two groups of heat exchange components (2), the both ends of shell (1) length direction are communicated, and each group of heat exchange components (2) includes multiple heat exchange pipes (21), and the end of heat exchange pipe (21) penetrates and extends the both sides of shell (1) width direction, and the heat exchange pipe (21) of each group of heat exchange components (2) penetrates corresponding support plate (3), Cleaning device (4) includes a pair of setting in the base frame (41) of heat exchange pipe (21) both ends, a pair of transmission assembly (42), a pair of support assembly (43) and multiple cleaning assembly (44), the bottom of base frame (41) extends towards shell (1) direction and is fixedly connected with shell (1) bottom, transmission assembly (42) is installed in base frame (41), cleaning assembly (44) is used to move in heat exchange pipe (21), to carry out dust removal, and the both ends of cleaning assembly (44) are fixedly connected with traction rope (45), and traction rope (45) is fixedly connected with corresponding transmission assembly (42), to drive traction rope (45) and cleaning assembly (44) to move through transmission assembly (42) rotation, support assembly (43) is set up outside the end of heat exchange pipe (21), is used to support cleaning assembly (44) moving out of heat exchange pipe (21), makes cleaning assembly (44) keep coaxial with heat exchange pipe (21).

2. A fluoroplastic steel air preheater for multi-source exhaust gas boilers according to claim 1, characterized in that: Transmission assembly (42) includes multiple interval setting rotation rod (421), multiple take-up shaft (422), multiple gear (423) and not less than one motor (424), and the both ends of rotation rod (421) are rotatably connected to the vertical both sides of base frame (41), and each rotation rod (421) is fixedly connected with multiple interval setting take-up shaft (422), gear (423) is engagedly connected between adjacent rotation rod (421), and the drive shaft of motor (424) is fixedly connected with rotation rod (421).

3. A multi-source exhaust gas boiler fluoroplastic steel air preheater according to claim 2, characterized in that: The interval of rotation rod (421) is same with the interval of adjacent heat exchange pipe (21) vertically, and the interval of take-up shaft (422) is same with the interval of adjacent heat exchange pipe (21) horizontally, and the end of take-up shaft (422) is fixedly connected with traction rope (45).

4. A fluoroplastic steel air preheater for multi-source exhaust gas boilers according to claim 1, characterized in that: Support assembly (43) includes the limiting ring (431) that is internally provided with air channel, air outlet ring (432), multiple horizontal pipes (433) and multiple vertical pipes (434), air outlet ring (432) is fixedly connected to the outer wall of limiting ring (432), and the end of each air outlet ring (432) away from heat exchange pipe (21) is fixedly connected with multiple air outlet rods (4321) internally provided with cavity, to communicate with air channel, horizontal pipe (433) is fixedly connected between adjacent air outlet ring (432), and vertical pipe (434) is fixedly connected between adjacent horizontal pipe (433), and the most bottom vertical pipe (434) extends downward and is fixedly connected to the bottom of base frame (41).

5. A fluoroplastic steel air preheater for multi-source exhaust gas boilers according to claim 4, characterized in that: The end of air outlet rod (4321) away from heat exchange pipe (21) is bent, and the bending portion is provided with air outlet towards heat exchange pipe (21), and the inner wall diameter of limiting ring (431) is same with the inner wall diameter of heat exchange pipe (21).

6. A fluoroplastic steel air preheater for multi-source exhaust gas boilers according to claim 1, characterized in that: The cleaning assembly (44) comprises a cleaning ring (441) and a pair of supporting rings (442). The middle part of the inner wall of the cleaning ring (441) is further extended to increase the wall thickness, and the two ends of the further extended part are inclined to form an included angle with the inner wall at the two ends of the cleaning ring (441). One end of the pair of supporting rings (442) is fixedly connected to the two ends of the further extended part, so that an included angle area is formed between the outer wall of the supporting ring (442) and the inner wall at the end of the cleaning ring (441).

7. A multi-source exhaust gas boiler fluoroplastic steel air preheater according to claim 6, characterized in that: The included angle area is set as a storage area (444) corresponding to the air outlet opened by the air outlet rod (4321). The other end of the outer wall of the pair of supporting rings (442) is bent outwardly to form a limiting part (4421). The cleaning ring (441) is made of a flexible material.

8. A multi-source exhaust gas boiler fluoroplastic steel air preheater according to claim 6, characterized in that: The cleaning assembly (44) further comprises a pair of supporting rods (443) arranged inside the cleaning ring (441) and arranged in cross shape, and the ends are fixedly connected to the inner walls of the pair of supporting rings (442), respectively.

9. A fluoroplastic steel air preheater for multi-source exhaust gas boilers according to claim 6, characterized in that: An avoiding cavity (4422) is arranged inside each supporting ring (442), and an avoiding assembly (46) is further arranged in the avoiding cavity (4422). The avoiding assembly (46) comprises a spring (461), a connecting ring (462) and a plurality of avoiding ropes (463). The connecting ring (462) is fixedly connected to the end of the spring (461) away from the limiting part (4421). One end of each avoiding rope (463) is fixedly connected to the inner wall at the end of the cleaning ring (441), and the other end is fixedly connected to the connecting ring (462) penetrating through the supporting ring (442). The end of the traction rope (45) is divided into a plurality of end heads, each of which extends into the avoiding cavity (4422) and is fixedly connected to the connecting ring (462).

10. A fluoroplastic steel air preheater for multi-source exhaust gas boilers according to claim 9, characterized in that: The avoiding rope (463) is elastic. The elastic force required for completely compressing the spring (461) is greater than the force required for driving the cleaning ring (441) and the supporting ring (442) to move, and the force required for the spring (461) to drive the cleaning ring (441) and the supporting ring (442) to move is less than the force required for the cleaning ring (441) to deform itself.

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