Composite pipe flue gas shunting type anti-corrosion air preheater and ash removal device thereof

Abstract

The invention discloses a composite pipe flue gas shunting type anti-corrosion air preheater and an ash removal device thereof, and belongs to the technical field of pipeline ash removal equipment, the composite pipe flue gas shunting type anti-corrosion air preheater comprises a shell and a pipe box used for sealing the end parts of the two sides of the shell, the pipe box is connected with the shell through a pipe plate, a pipe bundle is loaded in the shell, and the pipe bundle is composed of a plurality of bundle plates and a plurality of heat exchange pipes; the bundle plates at least comprise the first bundle plates and the second bundle plates, a plurality of vertical baffle rods are installed in the middles of the first bundle plates, a plurality of transverse baffle rods are installed in the middles of the second bundle plates, and the first bundle plates and the second bundle plates are arranged in the shell in a staggered mode. The heat exchange tubes are inserted into the second mounting grooves between the transverse baffle rods along the first mounting grooves between the adjacent vertical baffle rods, the ends, away from each other, of the heat exchange tubes are inserted into the tube plate, and the ash removal devices are placed in the heat exchange tubes and used for removing scaling on the inner walls of the heat exchange tubes.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pipeline ash removal equipment, and particularly relates to a composite pipe flue gas shunt type anti-corrosion air preheater and an ash removal device thereof. BACKGROUND

[0002] As a key heat exchange equipment of thermal systems such as coal-fired boilers and industrial furnaces, the core function of the air preheater is to preheat the combustion air through flue gas waste heat, thereby significantly improving the thermal efficiency of the system. The traditional tubular air preheater generally adopts a fixed tube bundle structure, and the flue gas longitudinally washes the outer wall of the heat exchange tube in the shell side, and the air flows in the tube side. However, this structure faces two major bottleneck problems in actual operation: low-temperature acid dew point corrosion at the flue gas outlet, and the air preheater is in the lowest temperature zone of the flue gas in the boiler. A large amount of sulfur trioxide contained in the flue gas condenses to form dew drops, i.e. "dew", when the heat exchange temperature drops to the dew point temperature of the sulfur trioxide. The sulfuric acid and sulfurous acid solution formed after "dew" has strong corrosiveness and is easy to cause corrosion to metal equipment, affect the heat exchange performance of the boiler, and cause safety hazards.

[0003] The air preheater ash blockage causes poor flue gas passage or even blockage, and the ash removal device has poor adaptability. The accumulated ash acts as a heat insulator between the flue gas and the tube wall, causing the wall temperature to decrease, and low-temperature dew point corrosion occurs under the accumulated ash. After the air preheater is corroded, the large pressure difference between the inside and outside of the tube wall makes the air leakage point larger and larger, and the surface finish deteriorates seriously, making the ash more likely to adhere and aggravating the air preheater ash blockage. The fixed scraper brush has a rigid structure and is difficult to fit the tube wall in different wear states, and there are ash removal dead angles. Excessive scraping can accelerate the thinning of the tube wall. Based on this, the composite pipe flue gas shunt type anti-corrosion air preheater and ash removal device are developed to replace the prior art. SUMMARY

[0004] The purpose of the present application is to provide a composite pipe flue gas shunt type anti-corrosion air preheater and ash removal device to solve the technical problem of the fixed scraper brush, which has a rigid structure and is difficult to fit the tube wall in different wear states, and there are ash removal dead angles, and excessive scraping can accelerate the thinning of the tube wall.

[0005] The above technical purpose of the present application is achieved by the following technical scheme: a composite pipe flue gas shunt type anti-corrosion air preheater and ash removal device, comprising a shell and a tube box for closing the two side ends of the shell, the tube box and the shell are connected through a tube plate, any one side of the tube box at the two side ends of the shell is an air side, and the other end is a closed side, the tube box on the air side is separated by an extension plate, one end of the extension plate is connected to the inner wall of the air side tube box, and the other end is fixedly connected with a tube bundle, characterized in that a tube bundle is loaded in the shell, and the tube bundle is composed of a plurality of bundle plates and a plurality of heat exchange tubes.

[0006] The bundle plate includes at least a first bundle plate and a second bundle plate, wherein multiple vertical baffles are installed in the middle of the first bundle plate and multiple horizontal baffles are installed in the middle of the second bundle plate. Multiple sets of the first bundle plate and the second bundle plate are arranged alternately inside the shell. The heat exchange tubes are inserted into the second mounting groove between multiple horizontal baffles along the first mounting groove between adjacent vertical baffles. The ends of the heat exchange tubes that are far apart from each other are inserted into the tube sheet.

[0007] A cleaning device is placed inside the heat exchange tube and is used to remove scale buildup on the inner wall of the heat exchange tube.

[0008] Furthermore: the dust removal device includes a first sealing plate and a second sealing plate, a rotating shaft is installed between the first sealing plate and the second sealing plate, the rotating shaft is driven by a micro motor, and a scraping component is installed on the rotating shaft.

[0009] Further: The scraping assembly includes a first fixed ring, a sliding ring, and a second fixed ring. The first fixed ring and the second fixed ring are mounted on a rotating shaft. The first fixed ring is hinged to a first swing rod, and the second fixed ring is hinged to a second swing rod. The other ends of the first swing rod and the second swing rod are rotatably connected to a mounting base. A flexible brush is mounted on the mounting base. A sliding ring is also mounted on the rotating shaft. A third swing rod is hinged to the sliding ring. The other end of the third swing rod is hinged to the mounting base. A first tension spring is sleeved on the rotating shaft between the sliding ring and the first fixed ring or the second fixed ring. One end of the first tension spring is connected to the sliding ring, and the other end of the first tension spring is connected to the first fixed ring or the second fixed ring.

[0010] Furthermore, the flexible brush is a nylon brush, a wire brush, or a spring scraper, selected according to the material of the heat exchange tube.

[0011] Furthermore: the scraping assembly includes a connecting rod and an adjusting seat connected to the connecting rod. The adjusting seat has an adjusting groove for mounting the brush. A spring swing arm is rotatably connected to the adjusting seat. The spring swing arm is connected to a pressure plate. The pressure plate contacts the bottom of the brush. A second tension spring is fixedly installed on the adjusting seat. The other end of the second tension spring is fixedly connected to the spring swing arm.

[0012] Compared with the prior art, the present invention has the following advantages: by using staggered first and second bundle plates, the shell is divided into multiple flow zones, and the flue gas changes direction when flowing through each flow zone, thereby improving the heat exchange efficiency. The vertical baffle of the first bundle plate guides the flue gas to flow longitudinally and prolongs the flue gas residence time. The transverse baffle of the second bundle plate forces the flue gas to laterally flush the heat exchange tube. On the other hand, through a specially designed cleaning device, the sliding ring slides on the rotating shaft under the action of the first tension spring, so that the flexible brush is always in close contact with the inner wall of the heat exchange tube during the swinging process of the first swing rod, the second swing rod and the third swing rod, automatically compensating for local deformation of the tube diameter or local structural problems. Attached Figure Description

[0013] Figure 1 is a structural diagram of the air preheater of the present application;

[0014] Figure 2 is a structural diagram of the first bundle plate of the present application;

[0015] Figure 3 is a structural diagram of the second bundle plate of the present application;

[0016] Figure 4 is a structural diagram of the ash cleaning device of the present application Figure 1 ;

[0017] Figure 5 is a structural diagram of the ash cleaning device of the present application Figure 2 ;

[0018] Figure 6 is a partial enlarged view of A in the present application Figure 5 .

[0019] In the figure: 1, shell; 2, tube box; 3, tube plate; 4, tube bundle; 5, heat exchange tube; 6, first bundle plate; 7, second bundle plate; 8, vertical baffle rod; 9, transverse baffle rod; 10, first mounting groove; 11, second mounting groove; 12, first sealing plate; 13, second sealing plate; 14, rotating shaft; 15, first fixed ring; 16, sliding ring; 17, second fixed ring; 18, first swing rod; 19, second swing rod; 20, mounting seat; 21, flexible brush; 22, third swing rod; 23, first tension spring; 24, connecting rod; 25, adjusting seat; 26, brush; 27, adjusting groove; 28, spring swing arm; 29, pressing plate; 30, second tension spring; 31, micro motor; 32, extension plate; 33, first push rod; 34, tube clamp; 35, second push rod. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application.

[0021] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0022] In the first embodiment of the present application, as Figure 1As shown, the composite tube flue gas split type anti-corrosion air preheater and its ash removal device, comprising a shell 1 and a tube box 2 for closing both ends of the shell 1, the tube box 2 is connected with the shell 1 through a tube plate 3, any one side of the tube box 2 at both ends of the shell 1 is an air side, and the other end is a closed side, the tube box 2 of the air side is separated by an extension plate 32, one end of the extension plate 32 is connected to the inner wall of the air side tube box 2, and the other end is fixedly connected with a tube bundle 4, characterized in that the tube bundle 4 is loaded in the shell 1, and the tube bundle 4 is composed of a plurality of bundle plates and a plurality of heat exchange tubes 5;

[0023] In the above technical solution: the material of the shell 1, the tube box 2 and the heat exchange tube 5 is the same, the heat exchange tube is composed of an outer layer of stainless steel, a middle layer of flexible heat conducting layer and an inner layer of carbon steel, wherein the outer layer material can be made of different stainless steel according to the customer situation, the outer layer stainless steel is selected as 316L stainless steel, the corrosion resistance of the 316L stainless steel is combined with the carbon steel to form a heat conducting composite tube, and flexible heat conducting materials are added between the two composite materials, so that the heat conducting coefficient of the composite material is improved, and the contact thermal resistance problem between the two materials is solved;

[0024] In the embodiment, the provided extension plate 32 is provided with a plurality of first installation grooves 12 and a plurality of second installation grooves 13, the first installation grooves 12 are arranged on the extension plate 32 in a staggered manner, the second installation grooves 13 are arranged on the extension plate 32 in a staggered manner, and the first installation grooves 12 and the second installation grooves 13 are arranged in a staggered manner. Figure 1 For reference, the left side of the shell 1 is an air side, the tube box 2 of the air side is separated into an air inlet side and an air outlet side by the extension plate 32, the left upper part of the shell 1 is provided with a flue gas inlet side, and the right lower part of the shell 1 is provided with a flue gas outlet side,

[0025] High-temperature flue gas enters the shell 1 from the flue gas inlet side on the left side of the shell 1, and is discharged from the flue gas outlet side on the right lower part of the shell 1 as the flue gas volume increases, during which the heat exchange tube 5 is contacted and heat exchanged, normal-temperature air enters the tube box 2 from the air inlet side and is blocked by the extension plate 32 to enter the lower heat exchange tube 5 and flow to the closed side tube box 2, the air entering the closed side tube box 2 enters the upper heat exchange tube 5 of the shell 1 and flows back to the air outlet side to be discharged for use, and the air is heated during the flow in the heat exchange tube 5.

[0026] The bundle plate at least comprises a first bundle plate 6 and a second bundle plate 7, wherein a plurality of vertical baffles 8 are installed in the middle of the first bundle plate 6, a plurality of horizontal baffles 9 are installed in the middle of the second bundle plate 7, the first bundle plate 6 and the second bundle plate 7 are arranged in multiple groups in the shell 1 in a staggered manner, the heat exchange tube 5 is inserted into the second installation groove 11 between the multiple horizontal baffles 9 along the first installation groove 10 between the adjacent vertical baffles 8, and the end parts of the heat exchange tubes 5 away from each other are inserted into the tube plate 3;

[0027] In the above technical solution: the vertical baffle rod 8 of the first baffle plate 6 and the horizontal baffle rod 9 of the second baffle plate 7, each first baffle plate 6 or second baffle plate 7 and the adjacent first baffle plate 6 or second baffle plate 7 form a flow field area, and the flue gas enters the first flow field area from the flue gas inlet side of the shell 1, and then the light flue gas is longitudinally divided when flowing through the vertical baffle rod 8, and the flue gas is forced to flow transversely when flowing through the horizontal baffle rod 9.

[0028] The ash removal device is placed in the heat exchange pipe 5 and is used for removing the scale on the inner wall of the heat exchange pipe 5.

[0029] The ash removal device comprises a first sealing plate 12 and a second sealing plate 13, a rotating shaft 14 is installed between the first sealing plate 12 and the second sealing plate 13, the rotating shaft 14 is driven by a micro motor 31, and a scraping assembly is installed on the rotating shaft 14.

[0030] In the above solution, the micro motor 31 is an explosion-proof remote program-controlled motor, the power supply of the micro motor 31 adopts a thread power supply, a propelling rod for propelling the ash removal device in the heat exchange pipe 5 is further installed on the first sealing plate 12, the propelling rod at least comprises a first propelling rod 33 and a second propelling rod 35, the adjacent first propelling rod 33 and second propelling rod 35 are fixedly connected through a pipe clamp 34, and the multi-section propelling rod can be connected according to requirements.

[0031] The scraping assembly comprises a first fixed ring 15, a sliding ring 16 and a second fixed ring 17, the first fixed ring 15 and the second fixed ring 17 are installed on the rotating shaft 14, the first fixed ring 15 is hinged to a first swing rod 18, the second fixed ring 17 is hinged to a second swing rod 19, the other end of the first swing rod 18 and the second swing rod 19 is rotationally connected to a mounting seat 20, a flexible brush 21 is installed on the mounting seat 20, the flexible brush 21 is a nylon brush, a steel wire brush or a spring scraper, and is selected according to the material of the heat exchange pipe 5, the sliding ring 16 is further installed on the rotating shaft 14, a third swing rod 22 is hinged to the sliding ring 16, the other end of the third swing rod 22 is hinged to the mounting seat 20, a first tension spring 23 is sleeved on the rotating shaft 14 between the sliding ring 16 and the first fixed ring 15 or the second fixed ring 17, one end of the first tension spring 23 is connected to the sliding ring 16, and the other end of the first tension spring 23 is connected to the first fixed ring 15 or the second fixed ring 17.

[0032] By adopting the above technical solution: the first sealing plate 12 and the second sealing plate 13 are provided with a seal on the contact surface with the inner wall of the shell 1, the seal is a movable seal, and a sealing ring can be selected, in the initial state, the first tension spring 23 is in a contracted state, so that the sliding ring 16 is in a state close to the second fixed ring 17, and at the same time, the third swing rod 22 is in a maximum outward swing angle when the sliding ring 16 is in the state close to the second fixed ring 17, at this time, the mounting seat 20 is in the highest position, and the highest position is slightly higher than the first sealing plate 12 and the second sealing plate 13.

[0033] In the maintenance and cleaning of the heat exchange pipe 5, the workers remove the pipe box 2 on both sides of the shell 1. After removal, the workers hold the dust cleaning device to press the mounting seat 20 and the steel wire brush to make the first swing rod 18, the second swing rod 19 and the third swing rod 22 swing. In the swing process of the third swing rod 22, the sliding ring 16 slides on the rotating shaft 14 to overcome the resistance of the first tension spring 23, so that the dust cleaning device is inserted into the heat exchange pipe 5. When there is no external force, the first tension spring 23 is reset to pull the sliding ring 16 to slide on the rotating shaft 14. In the sliding process of the sliding ring 16, the first swing rod 18, the second swing rod 19 and the third swing rod 22 swing to make the mounting seat 20 and the steel wire brush rise, so that the steel wire brush is always attached to the inner wall of the heat exchange pipe 5. The micro motor 31 is started to drive the rotating shaft 14 to rotate, which drives the first fixed ring 15, the second fixed ring 17 and the sliding ring 16 to rotate, so that the steel wire brush rotates to remove the dust on the inner wall of the heat exchange pipe 5.

[0034] It needs to be explained that the above scheme is only used for the conventional cleaning of the heat exchange pipe 5, and is used for the structure for brushing the inner wall of the heat exchange pipe 5 and the dust brushing. It cannot be used for the cleaning of viscous materials. In the cleaning process, the flexible compression mode of the first tension spring is used to compensate for the change of the inner diameter caused by the local structure.

[0035] Embodiment 2

[0036] The composite pipe flue gas shunt type anti-corrosion air preheater and its dust cleaning device and its dust cleaning device comprise a shell 1 and a pipe box 2 for closing the two side ends of the shell 1. The pipe box 2 is connected with the shell 1 through a tube sheet 3. The characteristic is that a tube bundle 4 is loaded in the shell 1. The tube bundle 4 is composed of a plurality of bundle plates and a plurality of heat exchange pipes 5.

[0037] In the above technical scheme: the material of the shell 1, the pipe box 2 and the heat exchange pipe 5 is the same. The heat exchange pipe is composed of an outer layer of stainless steel, a middle layer of flexible heat conducting layer and an inner layer of carbon steel. The outer layer material can be made of different stainless steel according to the customer's situation. The outer layer stainless steel is selected to be 316L stainless steel. The corrosion resistance of 316L stainless steel is combined with carbon steel to form a heat conducting composite pipe. Flexible heat conducting materials are added between the two composite materials to improve the heat conductivity of the composite material and solve the contact thermal resistance problem between the two materials.

[0038] In the embodiment, the provided drawings Figure 1 For reference, the left side of the shell 1 is the air side. The pipe box 2 on the air side is divided into an air inlet side and an air outlet side by an extension plate 32. The left upper part of the shell 1 is provided with a flue gas inlet side. The right lower part of the shell 1 is provided with a flue gas outlet side.

[0039] High-temperature flue gas enters the shell 1 from the flue gas inlet side on the left side of the shell 1. As the flue gas volume increases, it is discharged from the flue gas outlet side on the lower right side of the shell 1. During this process, it exchanges heat with the heat exchange tube 5. Room temperature air enters the tube box 2 from the air inlet side and is blocked by the extension plate before entering the lower heat exchange tube 5 and flowing to the closed tube box 2. The air entering the closed tube box 2 enters the heat exchange tube 5 at the upper part of the shell 1 and flows back to the air outlet side for discharge. The air is heated during the flow in the heat exchange tube 5.

[0040] The bundle plate includes at least a first bundle plate 6 and a second bundle plate 7, wherein multiple vertical baffle rods 8 are installed in the middle of the first bundle plate 6, and multiple horizontal baffle rods 9 are installed in the middle of the second bundle plate 7. Multiple sets of the first bundle plate 6 and the second bundle plate 7 are arranged alternately in the shell 1. The heat exchange tube 5 is inserted into the second mounting groove 11 between the multiple horizontal baffle rods 9 along the first mounting groove 10 between adjacent vertical baffle rods 8. The ends of the heat exchange tube 5 that are far apart from each other are inserted into the tube sheet 3.

[0041] A cleaning device is placed inside the heat exchange tube 5 to remove scale buildup on the inner wall of the heat exchange tube 5.

[0042] The dust removal device includes a first sealing plate 12 and a second sealing plate 13, a rotating shaft 14 is installed between the first sealing plate 12 and the second sealing plate 13, and a scraping component is installed on the rotating shaft 14.

[0043] In the above scheme, the micro motor 31 adopts an explosion-proof remote programmable motor, and the power supply of the micro motor 31 adopts thread power supply. A push rod for pushing the dust removal device into the heat exchange tube 5 is also installed on the first sealing plate 12. The push rod includes at least a first push rod 33 and a second push rod 35. The adjacent first push rod 33 and second push rod 35 are fixedly connected by pipe clamps 34. The multi-segment push rod can be connected as needed.

[0044] The scraping assembly includes a connecting rod 24 and an adjusting seat 25 connected to the connecting rod 24. The adjusting seat 25 has an adjusting groove 27 for mounting a brush 26. The brush 26 slides in the adjusting groove 27 and cannot be completely disengaged from the adjusting groove 27. This can be achieved by using a stepped adjusting groove 27 with a matching brush 26. A spring swing arm 28 is rotatably connected to the adjusting seat 25. The spring swing arm 28 is connected to a pressure plate 29, which contacts the bottom of the brush 26. A second tension spring 30 is fixedly mounted on the adjusting seat 25, and the other end of the second tension spring 30 is fixedly connected to the spring swing arm 28.

[0045] By adopting the above technical solution, a seal is installed on the contact surface between the first sealing plate 12 and the second sealing plate 13 and the inner wall of the housing 1. The sealing form is a movable seal, and a sealing ring can be selected.

[0046] When the heat exchange pipe 5 is maintained and cleaned, the staff removes the pipe box 2 on both sides of the shell 1, after removal, the staff holds the dust cleaning device, adjusts the height of the brush 26 and inserts it into the heat exchange pipe 5, when the brush 26 is pressed, the brush 26 is forced to act on the pressing plate 29, the pressing plate 29 is forced to cause the spring swing arm 28 to overcome the resistance of the second tension spring 30 to swing, when there is no external force, the second tension spring 30 is reset so that the pressing plate 29 works on the brush 26, thereby ensuring that the brush 26 is always attached to the inner wall of the heat exchange pipe 5;

[0047] It should be noted that the above scheme is only used for conventional maintenance of the heat exchange pipe, the structure for brushing the inner wall of the heat exchange pipe and the floating dust brush, and cannot be used for cleaning of viscous materials. The flexible pressing mode of the second tension spring is used to compensate for the change in the inner diameter caused by the local structure during the cleaning process.

[0048] The above is only the preferred embodiment of the present application, and it should be pointed out that for ordinary skilled persons in the technical field, a number of improvements can be made without departing from the principles of the present application, and these improvements should also be considered as the protection scope of the present application.

Claims

1. A composite tube flue gas split-flow type anti-corrosion air preheater and its ash removal device, comprising a shell (1) and tube boxes (2) for closing both side ends of the shell (1), the tube boxes (2) are connected with the shell (1) through tube sheets (3), any one side of the tube boxes (2) located at both side ends of the shell (1) is an air side, and the other end is a closed side, the tube boxes (2) of the air side are separated by extension plates (32), one end of the extension plates (32) is connected to the inner wall of the tube boxes (2) of the air side, and the other end is fixedly connected with tube bundles (4), characterized in that, A plurality of heat exchange tubes (5) are arranged in the shell (1) and a plurality of bundle plates and a plurality of heat exchange tubes (5) constitute a tube bundle (4); The bundle plates comprise at least a first bundle plate (6) and a second bundle plate (7), wherein a plurality of vertical baffle rods (8) are arranged in the middle of the first bundle plate (6), a plurality of horizontal baffle rods (9) are arranged in the middle of the second bundle plate (7), the first bundle plate (6) and the second bundle plate (7) are arranged in a plurality of groups in the shell (1) in a staggered manner, the heat exchange tubes (5) are inserted into the second installation slot (11) between the plurality of horizontal baffle rods (9) along the first installation slot (10) between adjacent vertical baffle rods (8), and the ends of the heat exchange tubes (5) away from each other are inserted into the tube plate (3). A soot cleaning device is arranged in the heat exchange tube (5) and is used for cleaning the scale on the inner wall of the heat exchange tube (5).

2. The composite tube, flue gas split, erosion control air preheater and its ash cleaning apparatus of claim 1, wherein: The soot cleaning device comprises a first sealing plate (12) and a second sealing plate (13), a rotating shaft (14) is arranged between the first sealing plate (12) and the second sealing plate (13), the rotating shaft (14) is driven by a micro motor (31), and a scraping assembly is arranged on the rotating shaft (14).

3. The composite tube, flue gas split, erosion control air preheater and its ash cleaning apparatus of claim 2, wherein: The scraping assembly comprises a first fixed ring (15), a sliding ring (16) and a second fixed ring (17), the first fixed ring (15) and the second fixed ring (17) are arranged on the rotating shaft (14), the first fixed ring (15) is hinged to a first swing rod (18), the second fixed ring (17) is hinged to a second swing rod (19), the other end of the first swing rod (18) and the second swing rod (19) is rotatably connected to a mounting seat (20), a flexible brush (21) is arranged on the mounting seat (20), the sliding ring (16) is also arranged on the rotating shaft (14), a third swing rod (22) is hinged to the sliding ring (16), the other end of the third swing rod (22) is hinged to the mounting seat (20), a first tension spring (23) is sleeved on the rotating shaft (14) between the sliding ring (16) and the first fixed ring (15) or the second fixed ring (17), one end of the first tension spring (23) is connected to the sliding ring (16), and the other end of the first tension spring (23) is connected to the first fixed ring (15) or the second fixed ring (17).

4. The composite tube, flue gas split, erosion control air preheater and its ash cleaning apparatus of claim 3, wherein: The flexible brush (21) is a nylon brush, a steel wire brush or a spring scraper, which is selected according to the material of the heat exchange tube (5).

5. The composite tube, flue gas split, erosion control air preheater and its ash cleaning apparatus of claim 2, wherein: The scraping assembly comprises a connecting rod (24) and an adjusting seat (25) connected to the connecting rod (24), the adjusting seat (25) is provided with an adjusting slot (27) for arranging a brush (26), a spring swing arm (28) is rotatably connected to the adjusting seat (25), the spring swing arm (28) is connected to a pressing plate (29), the pressing plate (29) is in contact with the bottom of the brush (26), a second tension spring (30) is fixedly arranged on the adjusting seat (25), and the other end of the second tension spring (30) is fixedly connected to the spring swing arm (28).

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