Automatic ash removal type thermal cycle supercritical CO2 flue gas heat exchanger and using method

Abstract

The invention discloses an automatic ash removal type thermal cycle supercritical CO2 flue gas heat exchanger which comprises a connecting frame, a first sealing cover and a second sealing cover are connected to the front side and the rear side of the connecting frame through bolts correspondingly, a dust suction assembly is arranged on the front side of the first sealing cover, and a heat exchange pipe is fixedly connected to the interior of the connecting frame; a plurality of heat conduction fins are fixedly connected to the heat exchange pipe, and one end of the heat exchange pipe is fixedly connected with a first air inlet pipe. According to the cleaning device, a servo motor drives a corresponding reciprocating lead screw to rotate, a cleaning assembly can be driven to reciprocate along a limiting rod through a mounting plate through transmission of a first chain wheel and a first chain, in the moving process of the cleaning assembly, an arranged gear is meshed with a rack, a corresponding rotating shaft can be driven to rotate, and through transmission of a second chain wheel and a second chain, the cleaning assembly is driven to rotate. And the rotating shafts can be driven to rotate, so that the connecting shafts arranged between the rotating shafts are driven to rotate, and the cleaning brushes can be driven to rotate to clean the exteriors of the heat exchange tubes and the heat conduction fins.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and in particular to an automatic dust-cleaning thermal cycle supercritical CO2 flue gas heat exchanger and a use method thereof. Background Art

[0002] The energy crisis in the world is becoming increasingly prominent. The energy-saving and emission-reduction technology of internal combustion engines has attracted more and more attention from the world. The waste heat recovery of internal combustion engines has huge energy-saving potential. The transcritical power cycle with CO2 as the working fluid is selected for the waste heat recovery power generation of internal combustion engines because of its outstanding miniaturization ability, strong applicability, safety and environmental protection. The CO2 flue gas heat exchanger is an important component in the cycle. The CO2 working fluid in the cycle absorbs the waste heat of the high-temperature exhaust gas of the internal combustion engine in the flue gas heat exchanger. Therefore, the performance of the CO2 flue gas heat exchanger directly determines the quality of the waste heat recovery performance.

[0003] After long-term use, the existing thermal cycle supercritical CO2 flue gas heat exchanger will have a reduced heat exchange effect because dust in the flue gas adheres to the heat exchange tubes. In addition, it is troublesome to disassemble the heat exchanger, and the heat exchange process needs to be stopped when cleaning. In order to overcome these disadvantages, the present invention provides an automatic cleaning thermal cycle supercritical CO2 flue gas heat exchanger and a method of use. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and to propose an automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger and a method of use.

[0005] In order to achieve the above-mentioned objectives, the present invention adopts the following technical scheme: an automatic dust cleaning type thermal cycle supercritical CO2 flue gas heat exchanger, comprising a connecting frame, a first sealing cover and a second sealing cover are bolted to the front and rear sides of the connecting frame respectively, a dust collection assembly is arranged on the front side of the first sealing cover, a heat exchange tube is fixedly connected to the inside of the connecting frame, a plurality of heat conducting fins are fixedly connected to the heat exchange tube, one end of the heat exchange tube is fixedly connected to the first air inlet pipe, the other end of the heat exchange tube is fixedly connected to the first air outlet pipe, the second air inlet pipe and the second air outlet pipe are fixedly connected to the middle positions of the upper and lower ends of the connecting frame respectively, a cleaning assembly is arranged inside the connecting frame, the upper and lower ends of the first sealing cover are fixedly connected to the limit rod, the upper and lower ends of the second sealing cover are rotatably connected to the reciprocating screw rod, and the rear sides of the upper ends of the first and second sealing covers are fixedly connected to the racks.

[0006] Furthermore, the front and rear outer rings of the connection frame are fixedly connected with first sealing frames, and the middle position of the first sealing frame is provided with a sealing groove.

[0007] Furthermore, the first sealing cover and the second sealing cover are both fixedly connected to a second sealing frame at the outer ring on one side, and the second sealing frame is fixedly connected to a sealing ring at the middle position, and the sealing rings are respectively connected to the corresponding sealing grooves.

[0008] Furthermore, the dust collection assembly includes a dust box and a circulating fan fixedly connected to the first sealing cover, the front end of the dust box is bolted with an end cover, and the bottom end of the dust box is provided with a filter element.

[0009] Furthermore, a first connecting pipe is fixedly connected between the upper end of the dust box and the first sealing cover, a second connecting pipe is fixedly connected between the output end of the circulating fan and the first sealing cover, a third connecting pipe is fixedly connected between the input end of the circulating fan and the dust box, a first valve and a one-way valve are fixedly connected at both ends of the first connecting pipe, and a second valve is fixedly connected to the second connecting pipe.

[0010] Furthermore, a servo motor is fixedly connected to an upper end of one side of the second sealing cover, an output end of the servo motor is fixedly connected to one end of a corresponding reciprocating screw rod, one end of each reciprocating screw rod is fixedly connected to a first sprocket, and the first sprockets are driven by a first chain.

[0011] Furthermore, the cleaning assembly includes mounting plates located on both sides, one end of the mounting plates is meshedly connected to the corresponding reciprocating screw, the other end of the mounting plates is slidably connected to the corresponding limit rod, a plurality of rotating shafts are rotatably connected to the mounting plates, one end of the rotating shaft located at the upper end is fixedly connected to a gear, and the gear is meshedly connected to the corresponding rack.

[0012] Furthermore, one opposite end of the rotating shaft is fixedly connected to a limited prism, the other end of the rotating shaft at the upper end and both ends of the remaining rotating shafts are fixedly connected to a second sprocket, and the corresponding second sprockets are driven by a second chain.

[0013] Furthermore, a connecting shaft is provided between the left and right adjacent rotating shafts, and limiting grooves are provided on both sides of the connecting shaft. The limiting grooves are connected to the corresponding limiting prisms, and a cleaning brush is fixedly connected to the connecting shaft.

[0014] Furthermore, the method comprises the following steps:

[0015] S1, the flue gas enters the sealed shell composed of the connecting frame, the first sealing cover and the second sealing cover through the second air inlet pipe, and then is discharged through the second air outlet pipe, the carbon dioxide gas enters the heat exchange tube through the first air inlet pipe, and then is discharged through the first air outlet pipe, and the carbon dioxide gas absorbs the heat of the flue gas for heat exchange through the heat conduction of the heat conduction fins and the heat exchange tube;

[0016] S2, the servo motor drives the corresponding reciprocating screw to rotate, and the transmission of the first sprocket and the first chain can drive the cleaning component to reciprocate along the limit rod through the mounting plate. During the movement of the cleaning component, the gear and the rack are meshed, which can drive the corresponding rotating shaft to rotate. Through the transmission of the second sprocket and the second chain, multiple rotating shafts can be driven to rotate, thereby driving the connecting shaft set between the rotating shafts to rotate, and then the cleaning brush can be driven to rotate to clean the outside of the heat exchange tube and the heat transfer fin;

[0017] S3. During the cleaning process, the first valve and the second valve are opened, and the circulating fan can draw the air in the sealed shell into the dust box through the first connecting pipe. The one-way valve can prevent air backflow. The filter element in the dust box can filter the drawn air so that the swept dust remains in the dust box. The filtered air flows back to the sealed shell through the third connecting pipe and the second connecting pipe, so that cleaning operations can be performed during the heat exchange process, and then the first valve and the second valve can be closed.

[0018] Beneficial effects of the present invention:

[0019] 1. In the automatic ash-cleaning heat cycle supercritical CO2 flue gas heat exchanger, the flue gas enters the sealed housing composed of the connecting frame, the first sealing cover and the second sealing cover through the second air inlet pipe, and then is discharged through the second air outlet pipe. The carbon dioxide gas enters the heat exchange tube through the first air inlet pipe, and then is discharged through the first air outlet pipe. After the heat conduction of the heat conduction fins and the heat exchange tube, the carbon dioxide gas absorbs the heat of the flue gas for heat exchange;

[0020] 2. In the automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger, the servo motor drives the corresponding reciprocating screw to rotate, and the first sprocket and the first chain drive the cleaning assembly to reciprocate along the limit rod through the mounting plate. During the movement of the cleaning assembly, the gear and the rack are meshed, which can drive the corresponding rotating shaft to rotate. Through the transmission of the second sprocket and the second chain, multiple rotating shafts can be driven to rotate, thereby driving the connecting shaft set between the rotating shafts to rotate, and then the cleaning brush can be driven to rotate to clean the heat exchange tube and the outside of the heat transfer fins;

[0021] 3. In the automatic dust-cleaning thermal cycle supercritical CO2 flue gas heat exchanger, during the cleaning process, the first valve and the second valve are opened, and the circulating fan provided can draw the air in the sealed shell into the dust box through the first connecting pipe. The one-way valve provided can prevent air backflow, and the filter element in the dust box can filter the drawn air so that the swept dust remains in the dust box. The filtered air flows back into the sealed shell through the third connecting pipe and the second connecting pipe, so that the cleaning operation can be performed during the heat exchange process, and then the first valve and the second valve can be closed. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the description of the specific implementation methods will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0023] Figure 1 : A front view of the present invention;

[0024] Figure 2 : Rear view of the present invention;

[0025] Figure 3 : Schematic diagram of the internal structure of the connection frame of the present invention;

[0026] Figure 4 : A schematic diagram of the cleaning assembly structure of the present invention;

[0027] Figure 5 : Schematic diagram of the connecting shaft structure of the present invention.

[0028] Figure 6 : A schematic diagram of the internal structure of the first sealing cover of the present invention;

[0029] Figure 7 : Schematic diagram of the internal structure of the second sealing cover of the present invention.

[0030] The reference numerals are as follows:

[0031] 1. Connecting frame; 2. First sealing cover; 3. Second sealing cover; 4. Dust collecting box; 5. End cover; 6. Circulating fan; 7. First connecting pipe; 8. Second connecting pipe; 9. Third connecting pipe; 10. First valve; 11. One-way valve; 12. Second valve; 13. Servo motor; 14. First sprocket; 15. First chain; 16. Heat exchange tube; 17. Heat conducting fin; 18. First air inlet pipe; 19. First air outlet pipe; 20. First sealing frame; 21. Sealing groove; 22. Second air inlet pipe; 23. Second air outlet pipe; 24. Cleaning assembly; 25. Mounting plate; 26. Rotating shaft; 27. Limiting prism; 28. Gear; 29. ​​Second sprocket; 30. Second chain; 31. Connecting shaft; 32. Cleaning brush; 33. Limiting groove; 34. Second sealing frame; 35. Sealing ring; 36. Limiting rod; 37. Rack; 38. Reciprocating screw. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] like Figure 1-7 As shown, the present invention has the following specific embodiments.

[0034] A kind of automatic dust cleaning type thermal cycle supercritical CO2 flue gas heat exchanger comprises a connecting frame 1, the front and rear sides of the connecting frame 1 are respectively bolted with a first sealing cover 2 and a second sealing cover 3, a dust collection assembly is arranged on the front side of the first sealing cover 2, a heat exchange tube 16 is fixedly connected inside the connecting frame 1, a plurality of heat conducting fins 17 are fixedly connected to the heat exchange tube 16, one end of the heat exchange tube 16 is fixedly connected with a first air inlet pipe 18, and the other end of the heat exchange tube 16 is fixedly connected with a first air outlet pipe 19, a second air inlet pipe 22 and a second air outlet pipe 23 are respectively fixedly connected at the middle positions of the upper and lower ends of the connecting frame 1, a cleaning assembly 24 is arranged inside the connecting frame 1, the upper and lower ends of the first sealing cover 2 are fixedly connected with a limit rod 36, the upper and lower ends of the second sealing cover 3 are rotatably connected with a reciprocating screw rod 38, and the rear sides of the upper ends of the first sealing cover 2 and the second sealing cover 3 are fixedly connected with a rack 37.

[0035] As shown in the figure, the first sealing frame 20 is fixedly connected to the outer rings of the front and rear sides of the connecting frame 1, and a sealing groove 21 is opened in the middle position of the first sealing frame 20. The second sealing frame 34 is fixedly connected to the outer rings of one side of the first sealing cover 2 and the second sealing cover 3, and a sealing ring 35 is fixedly connected to the middle position of the second sealing frame 34. The sealing ring 35 is respectively connected with the corresponding sealing groove 21. The set sealing ring 35 and the sealing groove 21 can improve the sealing between the first sealing cover 2, the second sealing cover 3 and the connecting frame 1, so that the connecting frame 1, the first sealing cover 2, and the second sealing cover 3 are formed into a sealed shell.

[0036] As shown in the figure, the dust collection assembly includes a dust box 4 and a circulating fan 6 fixedly connected to the first sealing cover 2, the front end of the dust box 4 is bolted with an end cover 5, the bottom end of the dust box 4 is provided with a filter element, a first connecting pipe 7 is fixedly connected between the upper end of the dust box 4 and the first sealing cover 2, a second connecting pipe 8 is fixedly connected between the output end of the circulating fan 6 and the first sealing cover 2, a third connecting pipe 9 is fixedly connected between the input end of the circulating fan 6 and the dust box 4, a first valve 10 and a one-way valve 11 are fixedly connected at both ends of the first connecting pipe 7, and a The second valve 12, during the cleaning process, open the first valve 10 and the second valve 12, the circulating fan 6 can draw the air in the sealed shell into the dust box 4 through the first connecting pipe 7, the one-way valve 11 can prevent air backflow, the filter element in the dust box 4 can filter the drawn air, so that the swept dust remains in the dust box 4, the filtered air flows back to the sealed shell through the third connecting pipe 9 and the second connecting pipe 8, so that the cleaning operation can be carried out during the heat exchange process, and then the first valve 10 and the second valve 12 can be closed.

[0037] As shown in the figure, a servo motor 13 is fixedly connected to the upper end of one side of the second sealing cover 3, and the output end of the servo motor 13 is fixedly connected to one end of the corresponding reciprocating screw rod 38, and one end of the reciprocating screw rod 38 is fixedly connected to the first sprocket 14, and the first sprockets 14 are transmitted through the first chain 15. The cleaning component 24 includes mounting plates 25 located on both sides, one end of the mounting plate 25 is meshed and connected with the corresponding reciprocating screw rod 38, and the other end of the mounting plate 25 is slidably connected to the corresponding limit rod 36. A plurality of rotating shafts 26 are rotatably connected to the mounting plate 25, one end of the rotating shaft 26 located at the upper end is fixedly connected to a gear 28, and the gear 28 is meshed and connected with the corresponding rack 37, and the opposite ends of the rotating shaft 26 are fixedly connected to the limited prism 27, and the other end of the rotating shaft 26 located at the upper end and both ends of the remaining rotating shafts 26 are fixedly connected to the second sprocket 29, and the corresponding second sprockets 29 are connected through The second chain 30 is used for transmission, and connecting shafts 31 are provided between the left and right adjacent rotating shafts 26. Limiting grooves 33 are provided on both sides of the connecting shaft 31. The limiting grooves 33 are connected with the corresponding limiting prisms 27 by clamping. Cleaning brushes 32 are fixedly connected to the connecting shafts 31. The servo motor 13 drives the corresponding reciprocating screw rod 38 to rotate. The transmission of the first sprocket 14 and the first chain 15 can drive the cleaning component 24 to reciprocate along the limiting rod 6 through the mounting plate 25. During the movement of the cleaning component 24, the gear 28 is meshed with the rack 7, which can drive the corresponding rotating shaft 26 to rotate. The transmission of the second sprocket 29 and the second chain 30 can drive multiple rotating shafts 26 to rotate, thereby driving the connecting shaft 31 set between the rotating shafts 26 to rotate, and then driving the cleaning brush 32 to rotate to clean the outside of the heat exchange tube 16 and the heat transfer fin 17.

[0038] The working principle is as follows: the flue gas enters into the sealed shell composed of the connecting frame 1, the first sealing cover 2 and the second sealing cover 3 through the second air inlet pipe 22, and is then discharged through the second air outlet pipe 23; the carbon dioxide gas enters into the heat exchange tube 16 through the first air inlet pipe 18, and is then discharged through the first air outlet pipe 19; after the heat conduction of the heat-conducting fins 17 and the heat exchange tube 16, the carbon dioxide gas absorbs the heat of the flue gas for heat exchange; the servo motor 13 drives the corresponding reciprocating screw rod 38 to rotate, and through the transmission of the first sprocket wheel 14 and the first chain 15, the cleaning component 24 can be driven to reciprocate along the limit rod 6 through the mounting plate 25; during the movement of the cleaning component 24, the gear 28 is meshed with the rack 7, which can drive the corresponding rotating shaft 26 to rotate, and through the second sprocket wheel 29 and the second chain The transmission of the strip 30 can drive the multiple rotating shafts 26 to rotate, thereby driving the connecting shaft 31 arranged between the rotating shafts 26 to rotate, and then driving the cleaning brush 32 to rotate to clean the outside of the heat exchange tube 16 and the heat-conducting fin 17. During the cleaning process, the first valve 10 and the second valve 12 are opened, and the circulating fan 6 set can draw the air in the sealed shell into the dust box 4 through the first connecting pipe 7. The one-way valve 11 set can prevent air backflow. The filter element in the dust box 4 can filter the drawn air so that the swept dust remains in the dust box 4. The filtered air flows back to the sealed shell through the third connecting pipe 9 and the second connecting pipe 8, so that the cleaning operation can be performed during the heat exchange process, and then the first valve 10 and the second valve 12 can be closed.

[0039] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An automatic ash-cleaning thermal cycle supercritical CO2 flue gas heat exchanger, comprising a connecting frame (1), characterized in that: The front and rear sides of the connecting frame (1) are respectively bolted to a first sealing cover (2) and a second sealing cover (3); a dust collecting assembly is arranged on the front side of the first sealing cover (2); a heat exchange tube (16) is fixedly connected inside the connecting frame (1); a plurality of heat-conducting fins (17) are fixedly connected to the heat exchange tube (16); one end of the heat exchange tube (16) is fixedly connected to a first air inlet pipe (18); the other end of the heat exchange tube (16) is fixedly connected to a first air outlet pipe (19); a second air inlet pipe (22) and a second air outlet pipe (23) are respectively fixedly connected at the middle positions of the upper and lower ends of the connecting frame (1); a cleaning assembly (24) is arranged inside the connecting frame (1); the upper and lower ends of the first sealing cover (2) are both fixedly connected to a limit rod (36); the upper and lower ends of the second sealing cover (3) are both rotatably connected to a reciprocating screw rod (38); and the upper rear sides of the first sealing cover (2) and the second sealing cover (3) are both fixedly connected to a rack (37).

2. The automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 1 is characterized in that: The front and rear outer rings of the connection frame (1) are both fixedly connected to a first sealing frame (20), and a sealing groove (21) is provided in the middle of the first sealing frame (20).

3. The automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 2 is characterized in that: A second sealing frame (34) is fixedly connected to the outer ring of one side of the first sealing cover (2) and the second sealing cover (3), and a sealing ring (35) is fixedly connected to the middle position of the second sealing frame (34). The sealing ring (35) is respectively connected to the corresponding sealing groove (21).

4. The automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 3 is characterized in that: The dust collection assembly comprises a dust box (4) and a circulating fan (6) fixedly connected to the first sealing cover (2); the front end of the dust box (4) is bolted to an end cover (5); and a filter element is arranged at the bottom end of the dust box (4).

5. The automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 4 is characterized in that: A first connecting pipe (7) is fixedly connected between the upper end of the dust collecting box (4) and the first sealing cover (2), a second connecting pipe (8) is fixedly connected between the output end of the circulating fan (6) and the first sealing cover (2), a third connecting pipe (9) is fixedly connected between the input end of the circulating fan (6) and the dust collecting box (4), a first valve (10) and a one-way valve (11) are fixedly connected at both ends of the first connecting pipe (7), and a second valve (12) is fixedly connected to the second connecting pipe (8).

6. The automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 5 is characterized in that: A servo motor (13) is fixedly connected to the upper end of one side of the second sealing cover (3); an output end of the servo motor (13) is fixedly connected to one end of a corresponding reciprocating screw rod (38); one end of each reciprocating screw rod (38) is fixedly connected to a first sprocket wheel (14); and the first sprocket wheels (14) are driven by a first chain (15).

7. The automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 6 is characterized in that: The cleaning assembly (24) comprises mounting plates (25) located on both sides, one end of the mounting plates (25) is meshedly connected to a corresponding reciprocating screw rod (38), the other end of the mounting plates (25) is slidably connected to a corresponding limit rod (36), a plurality of rotating shafts (26) are rotatably connected to the mounting plates (25), one end of the rotating shaft (26) located at the upper end is fixedly connected to a gear (28), and the gear (28) is meshedly connected to a corresponding rack (37).

8. The automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 7 is characterized in that: The opposite ends of the rotating shaft (26) are fixedly connected to the limited prism (27), the other end of the rotating shaft (26) located at the upper end and both ends of the remaining rotating shafts (26) are fixedly connected to the second sprocket (29), and the corresponding second sprockets (29) are driven by a second chain (30).

9. The automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 8, characterized in that: A connecting shaft (31) is provided between the rotating shafts (26) adjacent to each other on the left and right sides. Limiting grooves (33) are provided on both sides of the connecting shaft (31). The limiting grooves (33) are connected to corresponding limiting prisms (27) by clamping. A cleaning brush (32) is fixedly connected to the connecting shaft (31).

10. A method for using an automatic cleaning thermal cycle supercritical CO2 flue gas heat exchanger, characterized in that: The method is based on an automatic cleaning type thermal cycle supercritical CO2 flue gas heat exchanger according to claim 9, and the method comprises the following steps: S1, the flue gas enters into a sealed housing composed of a connecting frame (1), a first sealing cover (2) and a second sealing cover (3) through the second air inlet pipe (22), and is then discharged through the second air outlet pipe (23); the carbon dioxide gas enters into a heat exchange tube (16) through the first air inlet pipe (18), and is then discharged through the first air outlet pipe (19); after heat conduction through the heat conducting fins (17) and the heat exchange tube (16), the carbon dioxide gas absorbs heat from the flue gas for heat exchange; S2, the servo motor (13) drives the corresponding reciprocating screw rod (38) to rotate, and through the transmission of the first sprocket (14) and the first chain (15), the cleaning component (24) can be driven to reciprocate along the limit rod (6) through the mounting plate (25). During the movement of the cleaning component (24), the gear (28) is meshed with the rack (7), which can drive the corresponding rotating shaft (26) to rotate. Through the transmission of the second sprocket (29) and the second chain (30), multiple rotating shafts (26) can be driven to rotate, thereby driving the connecting shaft (31) arranged between the rotating shafts (26) to rotate, and then driving the cleaning brush (32) to rotate to clean the outside of the heat exchange tube (16) and the heat transfer fin (17); S3. During the cleaning process, the first valve (10) and the second valve (12) are opened, and the circulating fan (6) can draw the air in the sealed housing through the first connecting pipe (7) into the dust collecting box (4). The one-way valve (11) can prevent air backflow. The filter element in the dust collecting box (4) can filter the drawn air so that the swept dust remains in the dust collecting box (4). The filtered air flows back into the sealed housing through the third connecting pipe (9) and the second connecting pipe (8), so that the cleaning operation can be carried out during the heat exchange process. Then the first valve (10) and the second valve (12) can be closed.

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