Hot air recycling mechanism

Abstract

The utility model relates to the technical field of coating machine especially relates to hot -blast recycling mechanism. Its technical scheme includes exhaust main pipeline, fresh wind cold -blast air supply pipeline, hot -blast recycling pipe, one end of hot -blast recycling pipe is linked with RTO device, first oven assembly, second oven assembly, third oven assembly, fourth oven assembly, first oven assembly, second oven assembly, third oven assembly, fourth oven assembly are linked with exhaust main pipeline, fresh wind cold -blast air supply pipeline, hot -blast recycling pipe respectively through the pipeline and communicate. The utility model can realize the dynamic deployment of oven heat energy, accurately match the heat demand difference of different ovens, reduce the additional energy consumption input of the heat -demanding oven, solve the problem that the prior art leads to high energy consumption and difficult carbon emission control due to the lack of heat energy deployment capacity, realize efficient energy saving and emission reduction.

Description

Technical Field

[0001] This utility model relates to the field of coating machine technology, and in particular to a hot air recycling mechanism. Background Technology

[0002] In the coating process of a coating machine, the hot air recycling mechanism is one of the core supporting equipment. Its main function is to exhaust the waste gas containing volatile organic compounds generated during the drying of substrates in each oven of the coating machine, treat it through a regenerative thermal oxidizer, recover the high-temperature heat generated by the RTO unit, and reintroduce it into each oven through the hot air recycling pipe, replacing part of the fresh heating air. This satisfies the drying requirements for solvent evaporation and curing of the substrate coating, achieves energy recovery and utilization, reduces production energy consumption, and meets environmental emission requirements. Existing hot air recycling mechanisms do not have the ability to allocate and reuse the heat energy of the oven waste. This results in some ovens being idle due to process adjustments, batch changes, etc., and a large amount of residual heat inside cannot be recovered and can only be naturally dissipated, causing serious heat energy waste, which in turn increases production energy consumption and carbon emissions, making it difficult to achieve high-efficiency energy saving and emission reduction. Therefore, this utility model proposes a hot air recycling mechanism. Utility Model Content

[0003] The purpose of this invention is to address the problem that in the background technology, the hot air recycling mechanism does not have the ability to allocate and reuse the heat energy of the oven waste heat. This results in some ovens being idle due to process adjustments, batch switching, etc., and a large amount of residual heat inside cannot be recovered and can only be naturally dissipated, causing serious waste of heat energy, which in turn increases production energy consumption and carbon emissions, making it difficult to achieve high-efficiency energy saving and emission reduction. Therefore, a hot air recycling mechanism is proposed.

[0004] The technical solution of this utility model is as follows: a hot air recycling mechanism, including an exhaust main duct, a fresh air and cold air supply duct, and a hot air recycling pipe, one end of which is connected to an RTO device; a first oven assembly, a second oven assembly, a third oven assembly, and a fourth oven assembly, which are respectively connected to the exhaust main duct, the fresh air and cold air supply duct, and the hot air recycling pipe through pipes.

[0005] Optionally, the first oven assembly includes a first chamber, on which a first air outlet pipe and a first air inlet pipe are connected. A first exhaust fan is installed at one end of the first air outlet pipe, and a first connecting pipe is connected to the output end of the first exhaust fan. One end of the first connecting pipe is connected to the main exhaust pipe, and a first supply fan is connected to one end of the first air inlet pipe. The first supply fan is connected to a fresh air / cold air supply pipe and a hot air return pipe, respectively. A first connecting pipe is fixedly installed on the first chamber, and one end of the first connecting pipe is connected to the first supply fan.

[0006] Optionally, the second oven assembly includes a second chamber, on which a second air outlet pipe and a second air inlet pipe are connected. A second exhaust fan is installed at one end of the second air outlet pipe, and a second connecting pipe is connected to the output end of the second exhaust fan. One end of the second connecting pipe is connected to the main exhaust pipe. A second blower is connected to one end of the second air inlet pipe. The second blower is connected to a fresh air / cold air supply pipe and a hot air return pipe, respectively. A second connecting pipe is fixedly installed on the second chamber, and one end of the second connecting pipe is connected to the second blower.

[0007] Optionally, the third oven assembly includes a third chamber, on which a third air outlet pipe and a third air inlet pipe are connected. A third exhaust fan is installed at one end of the third chamber, and a third connecting pipe is connected to one end of the third exhaust fan. The third connecting pipe is connected to the main exhaust pipe and the hot air return pipe, respectively. A third blower is connected to one end of the third air inlet pipe, and one end of the third blower is connected to the fresh air and cold air supply pipe. A third connecting pipe is fixedly installed on the third chamber, and one end of the third connecting pipe is connected to the third blower.

[0008] Optionally, the fourth oven assembly includes a fourth chamber, on which a fourth air outlet pipe and a fourth air inlet pipe are connected. A fourth exhaust fan is installed at one end of the fourth chamber, and a fourth connecting pipe is connected to one end of the fourth exhaust fan. The fourth connecting pipe is connected to the main exhaust pipe and the hot air return pipe, respectively. A fourth supply fan is connected to one end of the fourth air inlet pipe, and one end of the fourth supply fan is connected to the fresh air and cold air supply pipe. A fourth connecting pipe is fixedly installed on the fourth chamber, and one end of the fourth connecting pipe is connected to the fourth supply fan.

[0009] Optionally, a first exhaust valve is provided at the connection between the first and second connecting pipes and the main exhaust pipe.

[0010] Optionally, the first and second blowers are four-way pipes, and a first return air valve is provided at the connection between the first air inlet pipe and the first blower and the second air inlet pipe and the second blower.

[0011] Optionally, proportional air valves are respectively installed at the connection points of the first and second air blowers with the fresh air / cooled air supply duct and the hot air return duct.

[0012] Optionally, the third and fourth connecting pipes are tee pipes, and a second exhaust air valve and a hot air return air valve are respectively installed at the connection points of the third and fourth connecting pipes with the main exhaust pipe and the hot air return pipe.

[0013] Optionally, a second return air valve is provided at the connection between the third air inlet pipe and the third air supply fan and the fourth air inlet pipe and the fourth air supply fan, and a fresh air valve is provided at the connection between the third air supply fan and the fourth air supply fan and the fresh air / cooled air supply pipe.

[0014] In summary, this application includes at least one of the following beneficial technical effects: This utility model achieves dynamic allocation of oven heat energy by using a four-way pipe structure of the first and second oven components' first and second blowers, and an independent connection structure of the third and fourth oven components' third and fourth blowers. It also incorporates the adjustment functions of proportional air valves, first return air valves, second return air valves, and fresh air valves, as well as an independent connection design between the hot air return pipe, fresh air and cold air supply pipes, and each oven component. This allows for precise matching of the heat demand differences of different ovens, reducing the additional energy input of ovens requiring heat, and solving the problems of high energy consumption and difficult carbon emission control caused by the lack of heat energy allocation capabilities in existing technologies. This results in high efficiency, energy saving, and emission reduction. Furthermore, this utility model, through the connection design of the hot air return pipe with the third and fourth oven components, combined with the three-way pipe structure of the third and fourth connecting pipes, the cooperation of the second exhaust air valve and the hot air return air valve, and the power transmission structure of the third and fourth exhaust fans, realizes the directional recovery and reuse of residual heat inside the empty oven after process adjustment and batch switching. This solves the problem of the waste heat of the empty oven being unable to be recovered and naturally dissipated in the prior art, thus reducing heat energy waste. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the hot air recycling mechanism; Figure 2 yes Figure 1 A schematic diagram of the structure of the first drying oven assembly; Figure 3 yes Figure 1 Schematic diagram of the structure of the second drying oven assembly; Figure 4 yes Figure 1 Schematic diagram of the structure of the third drying oven assembly; Figure 5 yes Figure 1 A schematic diagram of the structure of the fourth drying oven assembly.

[0016] Figure label: 1. Main exhaust duct; 2. Fresh air / cooled air supply duct; 3. Hot air recirculation duct; 4. First oven assembly; 41. First chamber; 42. First air outlet duct; 43. First air inlet duct; 44. First exhaust fan; 45. First connecting pipe; 46. First blower; 47. First connecting pipe; 5. Second oven assembly; 51. Second chamber; 52. Second air outlet duct; 53. Second air inlet duct; 54. Second exhaust fan; 55. Second connecting pipe; 56. Second blower; 57. Second connecting pipe; 6. Third oven assembly; 61. Third chamber; 62. Third air outlet duct; 63. Third air inlet duct; 64. Third exhaust fan; 65. Third connecting pipe; 66. Third supply fan; 67. Third connecting pipe; 7. Fourth oven assembly; 71. Fourth chamber; 72. Fourth air outlet duct; 73. Fourth air inlet duct; 74. Fourth exhaust fan; 75. Fourth connecting pipe; 76. Fourth supply fan; 77. Fourth connecting pipe; 8. First exhaust air valve; 9. First return air valve; 10. Proportional air valve; 11. Second exhaust air valve; 12. Hot air return valve; 13. Second return air valve; 14. Fresh air valve. Detailed Implementation

[0017] The technical solution of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this utility model, but not all embodiments.

[0018] The components of the present invention embodiments described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0019] Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0020] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0022] Example like Figure 1 As shown, the hot air recycling mechanism proposed in this utility model includes an exhaust main duct 1, a fresh air / cold air supply duct 2, and a hot air recycling pipe 3. The three main ducts are arranged parallel to the main body of the equipment and fixed by a bracket. One end of the hot air recycling pipe 3 is connected to the RTO device through a flange seal. The four oven assemblies, namely the first oven assembly 4, the second oven assembly 5, the third oven assembly 6, and the fourth oven assembly 7, are symmetrically distributed and are respectively connected to the exhaust main duct 1, the fresh air / cold air supply duct 2, and the hot air recycling pipe 3 through branch pipes with sealing gaskets.

[0023] like Figure 1 and Figure 2 As shown, the first oven assembly 4 includes a first chamber 41. The first chamber 41 has a built-in temperature sensor that can monitor the temperature inside the chamber in real time. A first air outlet pipe 42 and a first air inlet pipe 43 are connected to the first chamber 41 by a flange seal. The first air outlet pipe 42 serves as a waste gas discharge channel, and the first air inlet pipe 43 serves as a hot air input channel. A first exhaust fan 44 is bolted to one end of the first air outlet pipe 42. The output end of the first exhaust fan 44 is connected to a first connecting pipe 45 through a reducing joint. One end of the first connecting pipe 45 is connected to the main exhaust pipe 1. Vertically connected, the first connecting pipe 45 is connected to the exhaust main pipe 1 by a flange and a first exhaust valve 8 is installed. The first exhaust valve 8 is a shut-off valve. One end of the first air inlet pipe 43 is connected to a first air supply fan 46 by a quick connector. The first air supply fan 46 is connected to the fresh air and cold air supply pipe 2 and the hot air return pipe 3 by pipes with valve interfaces. The first connecting pipe 47 is fixedly installed on the first housing 41 by welding. The first connecting pipe 47 is made of 304 stainless steel and one end is connected to the return air interface of the first air supply fan 46.

[0024] like Figure 1 and Figure 3As shown, the second oven assembly 5 includes a second chamber 51. The second chamber 51 has a built-in temperature sensor and is identical in specifications to the first chamber 41. A second air outlet duct 52 and a second air inlet duct 53 are connected to the second chamber 51 via a flange seal. The second air outlet duct 52 serves as a waste gas discharge channel, and the second air inlet duct 53 serves as a hot air input channel. A second exhaust fan 54 is bolted to one end of the second air outlet duct 52. The output end of the second exhaust fan 54 is connected to a second connecting pipe 55 via a reducing connector. One end of the second connecting pipe 55 is connected to the main exhaust pipe. The second connecting pipe 55 is vertically connected to the main exhaust pipe 1. A first exhaust valve 8 is installed at the connection between the second connecting pipe 55 and the main exhaust pipe 1 via a flange. The first exhaust valve 8 is a shut-off valve. One end of the second air inlet pipe 53 is connected to a second air supply fan 56 via a quick connector. The second air supply fan 56 is connected to the fresh air and cold air supply pipe 2 and the hot air return pipe 3 via pipes with valve interfaces. A second connecting pipe 57 is fixedly installed on the second housing 51 by welding. The second connecting pipe 57 is made of 304 stainless steel and one end is connected to the return air interface of the second air supply fan 56.

[0025] like Figure 1 and Figure 4 As shown, the third oven assembly 6 includes a third chamber 61. The third chamber 61 has a built-in temperature sensor for real-time monitoring of the internal temperature. A third exhaust duct 62 and a third inlet duct 63 are connected to the third chamber 61 via a flange seal. The third exhaust duct 62 serves as a waste gas discharge channel, and the third inlet duct 63 serves as a cold air input channel. A third exhaust fan 64 is bolted to one end of the third chamber 61. A third connecting pipe 65 is connected to one end of the third exhaust fan 64 via a reducing connector. 5 adopts a three-way pipe structure, the pipe body is made of 304 stainless steel, and is connected to the main exhaust pipe 1 and the hot air return pipe 3 through flanges respectively. One end of the third air inlet pipe 63 is connected to the third air supply fan 66 through a quick connector. One end of the third air supply fan 66 is connected to the fresh air and cold air supply pipe 2 through a pipe with a valve interface. The third housing 61 is fixedly installed with a third connecting pipe 67 by welding. The third connecting pipe 67 is made of 304 stainless steel, and one end is connected to the return air interface of the third air supply fan 66. like Figure 1 and Figure 5As shown, the fourth oven assembly 7 includes a fourth chamber 71, which is identical in specifications to the third chamber 61. A fourth exhaust duct 72 and a fourth inlet duct 73 are connected to the fourth chamber 71 via a flange seal. The fourth exhaust duct 72 serves as a waste gas discharge channel, and the fourth inlet duct 73 serves as a cold air input channel. A fourth exhaust fan 74 is bolted to one end of the fourth chamber 71, and a fourth connecting pipe 75 is connected to one end of the fourth exhaust fan 74 via a reducing connector. The fourth connecting pipe 75 is a tee. The pipe structure is made of 304 stainless steel and is connected to the main exhaust pipe 1 and the hot air return pipe 3 through flanges. One end of the fourth air inlet pipe 73 is connected to the fourth air supply fan 76 through a quick connector. One end of the fourth air supply fan 76 is connected to the fresh air and cold air supply pipe 2 through a pipe with a valve interface. The fourth connecting pipe 77 is fixedly installed on the fourth housing 71 by welding. The fourth connecting pipe 77 is made of 304 stainless steel and one end is connected to the return air interface of the fourth air supply fan 76.

[0026] like Figures 1 to 4 As shown, the first blower 46 and the second blower 56 are integrated four-way pipe structures, and all four interfaces are provided with sealing grooves. The connection ports of the first air inlet pipe 43 and the first blower 46, and the connection ports of the second air inlet pipe 53 and the second blower 56 are respectively provided with a first return air valve 9 through flanges. The first return air valve 9 is an adjustable air valve.

[0027] Furthermore, at the connection ports of the first blower 46 and the fresh air-cooled air supply duct 2, the connection port of the first blower 46 and the hot air return pipe 3, the connection port of the second blower 56 and the fresh air-cooled air supply duct 2, and the connection port of the second blower 56 and the hot air return pipe 3, a proportional air valve 10 is respectively installed through a flange. The proportional air valve 10 can precisely adjust the opening degree.

[0028] Secondly, the third connecting pipe 65 and the fourth connecting pipe 75 are cast steel tee pipes with guide plates inside. A second exhaust air valve 11 is installed at the connection port of the third connecting pipe 65 and the main exhaust pipe 1, and at the connection port of the fourth connecting pipe 75 and the main exhaust pipe 1, respectively. The second exhaust air valve 11 is a shut-off type air valve. A hot air return air valve 12 is installed at the connection port of the third connecting pipe 65 and the hot air return pipe 3, and at the connection port of the fourth connecting pipe 75 and the hot air return pipe 3, respectively. The hot air return air valve 12 is a shut-off type air valve.

[0029] Furthermore, a second return air valve 13 is installed at the connection port of the third air inlet duct 63 and the third air supply fan 66, and at the connection port of the fourth air inlet duct 73 and the fourth air supply fan 76, respectively, via flanges. The second return air valve 13 is an adjustable air valve. A fresh air valve 14 is installed at the connection port of the third air supply fan 66 and the fresh air-cooled air supply duct 2, and at the connection port of the fourth air supply fan 76 and the fresh air-cooled air supply duct 2, respectively, via flanges. The fresh air valve 14 is a shut-off air valve.

[0030] The working principle of this embodiment is as follows: First, after the system starts, the RTO device continuously provides hot air and inputs it into the hot air return pipe 3, while the fresh air-cooled air supply pipe 2 simultaneously supplies fresh cold air. For the first oven assembly 4 and the second oven assembly 5, which require continuous and stable heating, both the first blower 46 and the second blower 56 adopt a four-way pipe structure. This four-way pipe is connected to the first air inlet pipe 43, the second air inlet pipe 53, the fresh air-cooled air supply pipe 2, the hot air return pipe 3, the first connecting pipe 47, and the second connecting pipe 57, respectively. During temperature adjustment, by adjusting the opening of the proportional air valve 10 at the connection between the first blower 46, the second blower 56, the fresh air-cooled air supply pipe 2, and the hot air return pipe 3, the mixing ratio of fresh cold air and RTO hot air can be precisely controlled, so that the temperature of the mixed air matches the target operating temperature of the first chamber 41 and the second chamber 51.

[0031] Simultaneously, the first return air valve 9 at the connection between the first air inlet pipe 43 and the first blower 46, and the second air inlet pipe 53 and the second blower 56, is opened, allowing some of the waste heat return air in the first housing 41 and the second housing 51 to flow back to the corresponding blower through the first connecting pipe 47 and the second connecting pipe 57. After mixing with fresh air and RTO hot air, it is sent back into the housing, reducing heat loss. The exhaust gas in the first housing 41 and the second housing 51 is discharged through the first air outlet pipe 42 and the second air outlet pipe 52. After being pressurized by the first exhaust fan 44 and the second exhaust fan 54, it is sent into the main exhaust pipe 1 through the first connecting pipe 45 and the second connecting pipe 55, and then through the first exhaust valve 8 at the connection between the first connecting pipe 45 and the second connecting pipe 55 and the main exhaust pipe 1, achieving unified treatment of exhaust gas.

[0032] For the third and fourth oven components 6 and 7, which require low heat input, their third and fourth air supply fans 66 and 76 are independently connected only to the fresh air / cooled air supply duct 2, the third air inlet duct 63, the fourth air inlet duct 73, the third connecting pipe 67, and the fourth connecting pipe 77. During operation, the fresh air valve 14 at the connection between the third and fourth air supply fans 66 and the fresh air / cooled air supply duct 2 is opened to deliver fresh, cool air into the third and fourth chambers 61 and 71. At the same time, the opening of the second return air valve 13 at the connection between the third air inlet duct 63 and the third air supply fan 66, and the fourth air inlet duct 73 and the fourth air supply fan 76 is adjusted so that some of the return air inside the chamber flows back to the corresponding air supply fan through the third connecting pipe 67 and the fourth connecting pipe 77, mixes with the fresh air, maintains the required temperature of the chamber, and avoids energy waste caused by excessive heat input.

[0033] Next, the exhaust gas from the third chamber 61 and the fourth chamber 71 is discharged through the third exhaust pipe 62 and the fourth exhaust pipe 72. After being pressurized by the third exhaust fan 64 and the fourth exhaust fan 74, it is sent into the main exhaust pipe 1 through the third connecting pipe 65 and the fourth connecting pipe 75, and then through the second exhaust valve 11 at the connection between the third connecting pipe 65 and the fourth connecting pipe 75 and the main exhaust pipe 1, to ensure that the exhaust gas emission meets the standards.

[0034] When the third oven assembly 6 and the fourth oven assembly 7 complete their production batch and enter an idle state, the large amount of residual heat inside their chambers is reused through a directional recovery structure. The third connecting pipe 65 and the fourth connecting pipe 75 are both tee pipes, connected to the main exhaust pipe 1 and the hot air return pipe 3, respectively. At this time, the fresh air valve 14 at the connection between the third blower 66 and the fourth blower 76 and the fresh air / cold air supply pipe 2, as well as the second return air valve 13 at the connection between the third air inlet pipe 63 and the fourth air inlet pipe 73 and the corresponding blower, are closed, stopping the fresh air input and the return air circulation within the chamber. Simultaneously, the second exhaust air valve 11 at the connection between the third connecting pipe 65 and the fourth connecting pipe 75 and the main exhaust pipe 1 is closed, and the hot air return air valve 12 at the connection between the third connecting pipe 65 and the fourth connecting pipe 75 and the hot air return pipe 3 is opened, so that the airflow channel of the empty oven and the hot air return pipe 3 form a connected loop.

[0035] Under the power of the third exhaust fan 64 and the fourth exhaust fan 74, the residual heat in the third chamber 61 and the fourth chamber 71 is extracted and sent to the hot air return pipe 3 through the third connecting pipe 65 and the fourth connecting pipe 75 of the three-way pipe structure. After mixing with the hot air provided by the RTO device, it is regulated again by the proportional air valve 10 at the first blower 46 and the second blower 56, and mixed with the fresh air and the return air from the first chamber 41 and the second chamber 51 to supplement the heat energy of the continuously operating first oven assembly 4 and second oven assembly 5, reducing the additional energy consumption input of the RTO device.

[0036] The above specific embodiments are merely optional embodiments of the hot air recycling mechanism of this utility model. Based on the technical solution of this utility model and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A hot air recycling mechanism, characterized in that, include: The exhaust main duct (1), the fresh air and cold air supply duct (2), and the hot air return duct (3) are connected at one end to the RTO device. The first oven assembly (4), the second oven assembly (5), the third oven assembly (6), and the fourth oven assembly (7) are respectively connected to the main exhaust pipe (1), the fresh air and cold air supply pipe (2), and the hot air return pipe (3) through pipes.

2. The hot air recycling mechanism according to claim 1, characterized in that, The first oven assembly (4) includes a first housing (41), on which a first air outlet pipe (42) and a first air inlet pipe (43) are connected. A first exhaust fan (44) is installed at one end of the first air outlet pipe (42), and a first connecting pipe (45) is connected to the output end of the first exhaust fan (44). One end of the first connecting pipe (45) is connected to the main exhaust pipe (1), and a first blower (46) is connected to one end of the first air inlet pipe (43). The first blower (46) is connected to the fresh air and cold air supply pipe (2) and the hot air return pipe (3) respectively. A first connecting pipe (47) is fixedly installed on the first housing (41), and one end of the first connecting pipe (47) is connected to the first blower (46).

3. The hot air recycling mechanism according to claim 2, characterized in that, The second oven assembly (5) includes a second housing (51), on which a second air outlet pipe (52) and a second air inlet pipe (53) are connected. A second exhaust fan (54) is installed at one end of the second air outlet pipe (52), and a second connecting pipe (55) is connected to the output end of the second exhaust fan (54). One end of the second connecting pipe (55) is connected to the main exhaust pipe (1), and a second blower (56) is connected to one end of the second air inlet pipe (53). The second blower (56) is connected to the fresh air and cold air supply pipe (2) and the hot air return pipe (3) respectively. A second connecting pipe (57) is fixedly installed on the second housing (51), and one end of the second connecting pipe (57) is connected to the second blower (56).

4. The hot air recycling mechanism according to claim 3, characterized in that, The third oven assembly (6) includes a third chamber (61), on which a third air outlet pipe (62) and a third air inlet pipe (63) are connected. A third exhaust fan (64) is installed at one end of the third chamber (61), and a third connecting pipe (65) is connected at one end of the third exhaust fan (64). The third connecting pipe (65) is connected to the main exhaust pipe (1) and the hot air return pipe (3) respectively. A third blower (66) is connected at one end of the third air inlet pipe (63), and one end of the third blower (66) is connected to the fresh air and cold air supply pipe (2). A third connecting pipe (67) is fixedly installed on the third chamber (61), and one end of the third connecting pipe (67) is connected to the third blower (66).

5. The hot air recycling mechanism according to claim 4, characterized in that, The fourth oven assembly (7) includes a fourth chamber (71), on which a fourth air outlet pipe (72) and a fourth air inlet pipe (73) are connected. A fourth exhaust fan (74) is installed at one end of the fourth chamber (71), and a fourth connecting pipe (75) is connected at one end of the fourth exhaust fan (74). The fourth connecting pipe (75) is connected to the main exhaust pipe (1) and the hot air return pipe (3) respectively. A fourth blower (76) is connected at one end of the fourth air inlet pipe (73), and one end of the fourth blower (76) is connected to the fresh air and cold air supply pipe (2). A fourth connecting pipe (77) is fixedly installed on the fourth chamber (71), and one end of the fourth connecting pipe (77) is connected to the fourth blower (76).

6. The hot air recycling mechanism according to claim 5, characterized in that, A first exhaust valve (8) is provided at the connection between the first connecting pipe (45) and the second connecting pipe (55) and the exhaust main pipe (1).

7. The hot air recycling mechanism according to claim 5, characterized in that, The first blower (46) and the second blower (56) are four-way pipes. The first air inlet pipe (43) and the first blower (46) are respectively provided with a first return air valve (9) at the connection between the first air inlet pipe (43) and the second air inlet pipe (53) and the second blower (56).

8. The hot air recycling mechanism according to claim 5, characterized in that, A proportional air valve (10) is provided at the connection points of the first blower (46) and the second blower (56) with the fresh air-cooled air supply pipe (2) and the hot air return pipe (3).

9. The hot air recycling mechanism according to claim 5, characterized in that, The third connecting pipe (65) and the fourth connecting pipe (75) are three-way pipes. The third connecting pipe (65) and the fourth connecting pipe (75) are respectively provided with a second exhaust air valve (11) and a hot air return air valve (12) at the connection points of the third connecting pipe (65) and the fourth connecting pipe (75) with the exhaust main pipe (1) and the hot air return pipe (3).

10. The hot air recycling mechanism according to claim 5, characterized in that, A second return air valve (13) is provided at the connection between the third air inlet pipe (63) and the third blower (66) and the fourth air inlet pipe (73) and the fourth blower (76), and a fresh air valve (14) is provided at the connection between the third blower (66) and the fourth blower (76) and the fresh air-cooled air supply pipe (2).

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