Ultra-high temperature heat pump dehumidification unit and papermaking drying cylinder circulation system

Abstract

The present application relates to a super-high-temperature heat pump dehumidifying unit and a papermaking drying cylinder circulation system, the super-high-temperature heat pump dehumidifying unit has a dehumidifying and cooling air duct and a drying and heating air duct connected together, the dehumidifying and cooling air duct is provided with first and second evaporation modules at intervals, and the drying and heating air duct is provided with first and second condensation modules at intervals; the external humid and hot air is sequentially passed through the dehumidifying and cooling air duct and the drying and heating air duct to form hot dry air output; and the dehumidifying and cooling air duct and the drying and heating air duct are respectively passed through first and second heat exchangers to exchange heat. In the papermaking drying cylinder circulation system, the drying cylinder is additionally provided with a hood to input hot dry air from the outside to the inside, so that the water in the wet paper sheet close to the outer surface of the drying cylinder is evaporated by internal and external heating, the inside and outside of the paper sheet are quickly and evenly heated, the drying speed and quality of the paper sheet are improved, and energy and production cost are saved.

Description

Technical Field

[0001] This invention relates to the field of dehumidification equipment technology, and in particular to heat pump dehumidification units and their applications. Background Technology

[0002] The papermaking process generally involves turning raw materials into pulp, followed by various well-known processes, among which drying is essential. Common drying equipment includes heating facilities, but the heating temperature is fixed and not controlled, limiting its applicability to specific types of paper. A paper drying cylinder is a machine used in papermaking machinery to continuously dry paper blanks formed from pulp. The basic working principle of a paper drying cylinder is to introduce steam into the cylinder, heating the outer surface of the cylinder and causing the moisture in the wet paper sheet adhering to it to evaporate, thus achieving the purpose of drying the paper sheet. The heat released by the steam is conducted to the paper sheet through the cylinder wall, and the condensate is discharged from the system through an internal siphon device. However, this method still suffers from the technical problem of uneven heating and a slower drying speed because the paper's adhering surface heats up faster than the outer surface.

[0003] Heat pumps, driven by a small amount of high-grade energy, can absorb heat from a low-temperature heat source and release it to a high-temperature heat source. Currently, heat pumps are widely used for dehumidification. Through a refrigeration cycle, moisture in indoor air can condense into water and be discharged, thereby reducing humidity. How to combine heat pump dehumidifiers with paper drying cylinders for paper drying, and how to improve paper drying efficiency while minimizing energy consumption and waste during paper production, have become key considerations in the industry.

[0004] Against this background, the applicant has proposed an ultra-high temperature heat pump dehumidifier unit and a paper drying cylinder circulation system using the ultra-high temperature heat pump dehumidifier unit, which is the application in this case. Summary of the Invention

[0005] The purpose of this invention is to provide an ultra-high temperature heat pump dehumidifier unit and a paper drying cylinder circulation system using the ultra-high temperature heat pump dehumidifier unit. The dehumidifier unit structure is optimized, the dehumidification and drying capacity is improved, and when used in the paper drying cylinder circulation system, the inner and outer sides of the paper are heated quickly and evenly, thereby improving the speed and quality of paper drying and saving energy and production costs.

[0006] To achieve the above objectives, the present invention provides an ultra-high temperature heat pump dehumidifier unit, which has a dehumidification and cooling air duct and a drying and heating air duct. At least a first evaporation module and a second evaporation module are arranged at intervals on the dehumidification and cooling air duct, and at least a first condensation module and a second condensation module are arranged at intervals on the drying and heating air duct. The end of the dehumidification and cooling air duct and the beginning of the drying and heating air duct are connected together, so that hot and humid air from the outside passes through the dehumidification and cooling air duct and the drying and heating air duct in sequence to form hot and dry air output. It also has at least a first heat exchanger and a second heat exchanger, and the dehumidification and cooling air duct and the drying and heating air duct are both connected to the first heat exchanger and the second heat exchanger, so that the dehumidification and cooling air duct and the drying and heating air duct exchange heat with each other when passing through the first heat exchanger and the second heat exchanger respectively.

[0007] The above scheme is further described as follows: the first evaporation module and the first condensation module are paired to form a heat pump system, and the second evaporation module and the second condensation module are paired to form a heat pump system; and both the first evaporation module and the second evaporation module are composed of two evaporators arranged in parallel, and correspondingly the first condensation module and the second condensation module are also composed of two condensers arranged in parallel, so that when the external hot and humid air passes through the first evaporation module and the second evaporation module, it passes through the two evaporators in sequence to cool down and dehumidify layer by layer, while when the hot and dry air passes through the first condensation module and the second condensation module, it passes through the two condensers to heat up layer by layer.

[0008] The above scheme is further described in that the first evaporation module and the second condensation module are both located between the first heat exchanger and the second heat exchanger, while the second evaporation module is located at the connection between the dehumidification and cooling air duct and the drying and heating air duct, and the first condensation module is located at the output end of the first heat exchanger.

[0009] A further aspect of the above scheme is that the refrigerant pipeline of the first evaporation module is also connected to a water source evaporator, which collects the heat from the steam condensate discharged from external equipment.

[0010] To achieve the above objectives, the paper drying cylinder circulation system provided by the present invention has the following features: Drying cylinder, A fan hood is set around the outer periphery of the drying cylinder. The fan hood is connected to the aforementioned ultra-high temperature heat pump dehumidifier unit through pipes to form a hot dry air circulation system. Steam is introduced into the drying cylinder to heat its outer surface, and hot dry air is blown from the hood to heat the wet paper sheets attached to the outer surface of the drying cylinder, so that the moisture in the wet paper sheets attached to the outer surface of the drying cylinder is evaporated by internal and external heating.

[0011] The above scheme is further described in that the hood is divided into a wet end and a dry end according to the rotation direction of the drying cylinder, and the wet end and the dry end are connected to the ultra-high temperature heat pump dehumidifier unit in parallel through pipes.

[0012] The above scheme is further described as follows: the wet end of the hood has a first air inlet and a first air return outlet, which are connected by a first circulating fan to form a first circulating loop. The first circulating loop also leads out a first bypass air return outlet and a first bypass air inlet. The dry end of the hood has a second air inlet and a second air return outlet, which are connected by a second circulating fan to form a second circulating loop. The second circulating loop also leads out a second bypass air return outlet and a second bypass air inlet. The first bypass air return outlet and the second bypass air return outlet are connected to the dehumidification and cooling duct of the ultra-high temperature heat pump dehumidifier unit through a pipe, so that the hot and humid return air is dehumidified and heated by the ultra-high temperature heat pump dehumidifier unit. The output end of the drying and heating duct of the ultra-high temperature heat pump dehumidifier unit is simultaneously connected to the first bypass air inlet and the second bypass air inlet through a pipe, so that hot and dry air is delivered to the first circulating loop and the second circulating loop respectively through the first bypass air inlet and the second bypass air inlet.

[0013] The above scheme is further provided that the inlet of the dehumidification and cooling air duct is equipped with a waste heat recovery device, so that the hot and humid return air output from the first bypass return air port and the second bypass return air port first passes through the waste heat recovery device before entering the dehumidification and cooling air duct. The waste heat recovery device is also equipped with a fresh air supply channel. The output end of the fresh air supply channel is connected to the first circulation loop and the second circulation loop respectively, so that the outside fresh air is input from the fresh air supply channel and absorbs the heat of the return air in the waste heat recovery device to be heated. The heated fresh air is then supplied to the first circulation loop and the second circulation loop.

[0014] The above scheme is further provided in that the first circulation loop is also provided with a first air heater, and the second circulation loop is also provided with a second air heater. The first air heater and the second air heater are respectively used to heat the hot dry air circulating in the first circulation loop and the second circulation loop.

[0015] A further aspect of the above scheme is that the drying cylinder is connected to a water source evaporator via a pipe, so that the steam condensate output by the drying cylinder is delivered to the water source evaporator for heating the refrigerant of the first evaporation module.

[0016] This invention is based on heat pump technology. Through the cooperation of multiple evaporation modules and multiple condensation modules, as well as multiple heat exchangers, external hot and humid air passes through dehumidification and cooling air ducts and drying and heating air ducts in sequence to form hot dry air output. The structure is compact and reasonable, with strong dehumidification and drying capabilities. It can produce ultra-high temperature hot dry air for use in paper drying cylinder circulation systems. In addition to the original internal heating mode, the drying cylinder is also equipped with a fan hood to input hot dry air from the outside in. This allows the moisture in the wet paper sheet that is in close contact with the outer surface of the drying cylinder to evaporate due to internal and external heating. The inner and outer sides of the paper sheet are heated quickly and evenly, improving the speed and quality of paper drying, and saving energy and production costs.

[0017] This invention also optimizes the paper drying cylinder circulation system, which not only improves drying efficiency but also facilitates operation control, reduces energy waste, and significantly improves waste heat recovery, thus helping to enhance paper drying and processing and meeting the requirements for industrial promotion and use. Attached Figure Description

[0018] Appendix Figure 1 This is a schematic diagram of a preferred embodiment of the ultra-high temperature heat pump dehumidifier unit of the present invention; Appendix Figure 2 for Figure 1 A schematic diagram of the embodiment applied to the paper drying cylinder circulation system. Detailed Implementation

[0019] The following will further explain the concept, specific structure, and technical effects of the invention in conjunction with the accompanying drawings, so as to fully understand the purpose, features, and effects of the invention.

[0020] It should be noted that in the description of this invention, the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," which indicate directional or positional relationships, are based on the directional or positional relationships shown in the accompanying drawings. These are used merely for ease of description and do not indicate or imply that the device or element must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0021] See Figure 1 As shown, the ultra-high temperature heat pump dehumidifier unit provided by the present invention is constructed based on heat pump technology. The ultra-high temperature heat pump dehumidifier unit has a dehumidification and cooling air duct 1 and a drying and heating air duct 2. The dehumidification and cooling air duct 1 is at least spaced apart with a first evaporation module 31 and a second evaporation module 32. The drying and heating air duct 2 is at least spaced apart with a first condensation module 41 and a second condensation module 42. The end of the dehumidification and cooling air duct 1 and the beginning of the drying and heating air duct 2 are connected together, so that the external hot and humid air passes through the dehumidification and cooling air duct 1 and the drying and heating air duct 2 in sequence to form hot and dry air output. It also has at least a first heat exchanger 51 and a second heat exchanger 52, and the dehumidification and cooling air duct 1 and the drying and heating air duct 2 are both connected to the first heat exchanger 51 and the second heat exchanger 52, so that the dehumidification and cooling air duct 1 and the drying and heating air duct 2 exchange heat with each other when passing through the first heat exchanger 31 and the second heat exchanger 32 respectively. It features multi-stage cooling and dehumidification as well as multi-stage heating and temperature rise, providing strong dehumidification and drying capabilities. It can produce ultra-high temperature hot dry air and is equipped with multi-stage heat exchange to improve waste heat recovery efficiency. It meets the requirements of dehumidification and drying while saving energy and has low investment costs.

[0022] Furthermore, in this embodiment, the first evaporation module 31 and the first condensation module 41 are paired to form a heat pump system, and the second evaporation module 32 and the second condensation module 42 are also paired to form a heat pump system, simplifying the structure and facilitating control. Both the first evaporation module 31 and the second condensation module 42 are located between the first heat exchanger 31 and the second heat exchanger 32, while the second evaporation module 32 is located at the connection between the dehumidification and cooling air duct 1 and the drying and heating air duct 2. The first condensation module 41 is located at the output end of the first heat exchanger 31. Both the first evaporation module 31 and the second evaporation module 32 are composed of two evaporators arranged in parallel, and correspondingly, the first condensation module 41 and the second condensation module 42 are also composed of two condensers arranged in parallel. This allows external hot and humid air to pass through the first evaporation module 31 and the second evaporation module 32, where it is cooled and dehumidified layer by layer through the two evaporators, improving dehumidification efficiency. Conversely, hot and dry air passes through the first condensation module 41 and the second condensation module 42, where it is heated layer by layer through the two condensers, facilitating temperature control and greatly increasing the temperature of the hot and dry air to obtain ultra-high temperature hot and dry air.

[0023] In this embodiment, the refrigerant pipeline of the first evaporation module 31 is also connected to a water source evaporator 6. The water source evaporator 6 collects the heat from the steam condensate discharged from external equipment, thereby improving the dehumidification efficiency of the first evaporation module 31. At the same time, it can also utilize external heat sources to recover heat and improve the operating efficiency of the heat pump system, thereby saving operating costs.

[0024] Figure 2 The paper drying cylinder circulation system provided by this invention uses the aforementioned ultra-high temperature heat pump dehumidifier unit, which includes: a drying cylinder 7 and a fan hood 8 arranged around the outer periphery of the drying cylinder. The fan hood 8 is connected to the aforementioned ultra-high temperature heat pump dehumidifier unit through pipes to form a hot dry air circulation system. Steam is introduced into the interior of the drying cylinder 7 to heat the outer surface of the drying cylinder, and hot dry air is blown from the fan hood 8 to heat the wet paper sheets attached to the outer surface of the drying cylinder, so that the moisture in the wet paper sheets tightly attached to the outer surface of the drying cylinder is evaporated by internal and external heating. The inner and outer sides of the paper sheets are heated quickly and evenly, improving the speed and quality of paper drying. During operation, the return air output from the fan hood is dehumidified, dried, and heated by the ultra-high temperature heat pump dehumidifier unit before being sent back to the fan hood for drying and heating. This cycle is repeated to realize the paper drying process using the ultra-high temperature heat pump dehumidifier unit in conjunction with the drying cylinder 7, thereby improving paper production efficiency and quality.

[0025] In this embodiment, the hood 8 is divided into a wet end and a dry end according to the rotation direction of the drying cylinder 7. The wet end and the dry end can be connected or separated, which is not limited here. The wet end and the dry end are connected to the ultra-high temperature heat pump dehumidifier unit in parallel through pipes, with a dual-path working mode for convenient management. The wet end of the hood 8 has a first air inlet 81 and a first return air inlet 82. The first air inlet 81 and the first return air inlet 82 are connected by a first circulating fan 831 to form a first circulation loop 83. The first circulation loop also leads out a first bypass return air inlet 832 and a first bypass air inlet 833. The dry end of the hood 8 has a second air inlet 84 and a second return air inlet 85. The second air inlet 84 and the second return air inlet 85 are connected by a second circulating fan 861 to form a second circulation loop 86. The second circulation loop also leads out a second bypass return air inlet 862 and a second... A bypass air inlet 863 is provided. The first bypass return air inlet 832 and the second bypass return air inlet 862 are connected to the dehumidification and cooling air duct 1 of the ultra-high temperature heat pump dehumidifier unit via pipes, so that the hot and humid return air is dehumidified and heated by the ultra-high temperature heat pump dehumidifier unit. The output end of the drying and heating air duct 2 of the ultra-high temperature heat pump dehumidifier unit is simultaneously connected to the first bypass air inlet 833 and the second bypass air inlet 863 via pipes, so that hot and dry air is delivered to the first circulation loop 83 and the second circulation loop 86 through the first bypass air inlet 833 and the second bypass air inlet 863 respectively. The two circulation loops supply air to the wet end and dry end of the fan hood 8 respectively, ensuring air volume and temperature, improving the heating and drying effect, and facilitating control. In this embodiment, dust screens 87 are further provided on the first return air inlet 82 and the second return air inlet 85 for filtration to ensure the regeneration effect of the return air.

[0026] In this embodiment, the inlet of the dehumidification and cooling duct 1 is equipped with a waste heat recovery device 9. The hot and humid return air output from the first bypass return air port 832 and the second bypass return air port 862 first passes through the waste heat recovery device 9 before entering the dehumidification and cooling duct 1. The waste heat recovery device 9 is also equipped with a fresh air supply channel 91. The output of the fresh air supply channel 91 is branched and connected to the first circulation loop 83 and the second circulation loop 86 respectively. Fresh air from outside is input through the fresh air supply channel 91 and absorbs the heat from the return air in the waste heat recovery device 9, thus increasing its temperature. The heated fresh air then replenishes the first circulation loop 83 and the second circulation loop 86, achieving the effects of fresh air supply and waste heat recovery, which helps improve the speed and quality of paper drying. The waste heat recovery device 9 is existing technology. Its working principle is to capture and collect waste heat generated during industrial production through a heat exchanger, transferring the heat energy in the waste heat to the medium that needs to be heated or preheated, thereby realizing the recovery and reuse of heat energy and reducing the demand for other energy sources. In this embodiment, a return air fan 92 is added to one end of the waste heat recovery unit 9 that is connected to the first bypass return air port 832 and the second bypass return air port 862. This improves the speed, balance and stability of the return air when it passes through the waste heat recovery unit 9 in a positive pressure manner. At the same time, a first air supply fan 11 is also provided on the side of the waste heat recovery unit 9 that is connected to the dehumidification and cooling air duct 1. This fan draws the return air in the waste heat recovery unit 9 and inputs it into the dehumidification and cooling air duct 1 in a positive pressure manner to improve the dehumidification and drying efficiency.

[0027] In this embodiment, the first circulation loop 83 is further provided with a first air heater 834, and the second circulation loop 86 is further provided with a second air heater 864. The first air heater 834 and the second air heater 864 are respectively used to heat the hot dry air circulating in the first circulation loop 83 and the second circulation loop 86, so that part of the return air is mixed with the hot dry air conveyed by the drying heating air duct 2 before being heated by the first air heater 834 or the second air heater 864, so as to ensure the temperature of the hot dry air and facilitate the paper drying process. In this embodiment, a second air supply fan 21 is provided on the conveying end of the drying heating air duct 2, which helps to evenly deliver the hot dry air to the first circulation loop 83 and the second circulation loop 86, ensuring the air pressure and air volume in the circulation loop.

[0028] In this embodiment, the first circulation loop 83 also includes a first internal circulation bypass pipe 835, which is connected between the first air inlet 81 and the first return air inlet 82 and controlled by a first air valve 836. At this time, the first air inlet 81 is also controlled by a second air valve 811, and the first return air inlet 82 is also controlled by a third air valve 821. The first circulation loop 83 operates as follows: Firstly, when the first air valve 836 is closed and the second air valve 811 and the third air valve 821 are open, the first circulation loop 83 provides hot dry air through the ultra-high temperature heat pump dehumidifier unit and cooperates with the first air heater 834 to deliver hot dry air to the wet end of the hood 8 for paper drying processing. Secondly, when the first air valve 836 is open, and the second air valve 811 and the third air valve 821 are open, the first circulation loop 83 delivers hot dry air for paper drying, while also partially circulating internally through the first internal circulation bypass pipe 835 to regulate the temperature, humidity, and airflow of the hot dry air in the first circulation loop 83 into the air hood 8. Thirdly, when the first air valve 836 is open, and the second air valve 811 and the third air valve 821 are closed, the first circulation loop 83 is in internal circulation, waiting to supply hot dry air to the air hood 8 again.

[0029] In this embodiment, the second circulation loop 86 also includes a second internal circulation bypass pipe 865, which is connected between the second air inlet 84 and the second return air inlet 85 and controlled by a fourth air valve 866. The second air inlet 84 is also controlled by a fifth air valve 841, and the second return air inlet 85 is controlled by a sixth air valve 851. The operation of the second circulation loop 86 is similar to that of the first circulation loop 83 and will not be described further here.

[0030] like Figure 2 As shown, in this embodiment, the drying cylinder 7 is connected to the water source evaporator 6 through a pipe, so that the steam condensate output by the drying cylinder 7 is delivered to the water source evaporator 6 to heat the refrigerant of the first evaporation module 31, thereby realizing efficient heat recovery and utilization, saving energy, and reducing system operating costs.

[0031] This invention, based on heat pump technology, utilizes multiple evaporation and condensation modules in collaboration with multiple heat exchangers. External humid air sequentially passes through dehumidification and cooling ducts and drying and heating ducts before being output as hot, dry air. The structure is compact and rational, with strong dehumidification and drying capabilities, producing ultra-high temperature hot, dry air for use in paper drying cylinder circulation systems. In addition to the traditional inside-out heating mode, the drying cylinder is equipped with a fan hood that introduces hot, dry air from the outside in. This ensures that the moisture in the wet paper sheet adhering to the outer surface of the drying cylinder evaporates due to internal and external heating, resulting in rapid and even heating of both the inner and outer surfaces of the paper sheet. This improves the speed and quality of paper drying, while saving energy and production costs. Furthermore, by optimizing the paper drying cylinder circulation system, not only is drying efficiency improved, but operation is also easier to control, reducing energy waste and significantly enhancing waste heat recovery. This contributes to improving paper drying processing and is suitable for widespread industrial application.

[0032] While preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention should not be limited to structures and operations that are exactly the same as those described above and shown in the drawings. Those skilled in the art can make many equivalent improvements and variations to the above embodiments through logical analysis, reasoning, or limited experiments without departing from the concept and scope of the present invention, but all such improvements and variations should fall within the scope of protection claimed by the present invention.

Claims

1. An ultra-high temperature heat pump dehumidifier unit, characterized in that, It has a dehumidification and cooling air duct (1) and a drying and heating air duct (2). The dehumidification and cooling air duct (1) is at least spaced apart with a first evaporation module (31) and a second evaporation module (32). The drying and heating air duct (2) is at least spaced apart with a first condensation module (41) and a second condensation module (42). The end of the dehumidification and cooling air duct (1) and the beginning of the drying and heating air duct (2) are connected together, so that the external hot and humid air passes through the dehumidification and cooling air duct (1) and the drying and heating air duct (2) in sequence to form hot and dry air output. It also has at least a first heat exchanger (51) and a second heat exchanger (52), and the dehumidification and cooling air duct (1) and the drying and heating air duct (2) are both connected to the first heat exchanger (51) and the second heat exchanger (52), so that the dehumidification and cooling air duct (1) and the drying and heating air duct (2) exchange heat with each other when passing through the first heat exchanger (31) and the second heat exchanger (32).

2. The ultra-high temperature heat pump dehumidifier unit according to claim 1, characterized in that, The first evaporation module (31) and the first condensation module (41) are paired to form a heat pump system, and the second evaporation module (32) and the second condensation module (42) are paired to form a heat pump system. The first evaporation module (31) and the second evaporation module (32) are both composed of two evaporators arranged in parallel. Correspondingly, the first condensation module (41) and the second condensation module (42) are also composed of two condensers arranged in parallel. When the hot and humid air passes through the first evaporation module (31) and the second evaporation module (32), it passes through the two evaporators in sequence to cool down and dehumidify layer by layer. When the hot and dry air passes through the first condensation module (41) and the second condensation module (42), it passes through the two condensers to heat up layer by layer.

3. The ultra-high temperature heat pump dehumidifier unit according to claim 1 or 2, characterized in that, The first evaporation module (31) and the second condensation module (42) are both located between the first heat exchanger (31) and the second heat exchanger (32), while the second evaporation module (32) is located at the connection between the dehumidification and cooling air duct (1) and the drying and heating air duct (2), and the first condensation module (41) is located at the output end of the first heat exchanger (31).

4. The ultra-high temperature heat pump dehumidifier unit according to claim 3, characterized in that, The refrigerant pipeline of the first evaporation module (31) is also connected to a water source evaporator (6), which collects the heat of the steam condensate discharged from the external equipment.

5. A paper drying cylinder circulation system, characterized in that, have: Drying cylinder (7) A fan hood (8) is provided around the outer periphery of the drying cylinder. The fan hood (8) is connected to the ultra-high temperature heat pump dehumidifier unit of any one of claims 1 to 4 through a pipe to form a hot dry air circulation system. Steam is introduced into the inside of the drying cylinder (7) to heat the outer surface of the drying cylinder, and hot dry air is blown in the hood (8) to heat the wet paper sheets attached to the outer surface of the drying cylinder, so that the moisture in the wet paper sheets attached to the outer surface of the drying cylinder is evaporated by internal and external heating.

6. The paper drying cylinder circulation system according to claim 5, characterized in that, The hood (8) is divided into a wet end and a dry end according to the rotation direction of the drying cylinder (7), and the wet end and the dry end are connected to the ultra-high temperature heat pump dehumidifier unit in parallel through pipes.

7. The paper drying cylinder circulation system according to claim 6, characterized in that, The wet end of the hood (8) has a first air inlet (81) and a first return air inlet (82), which are connected by a first circulating fan (831) to form a first circulating loop (83). The first circulating loop also leads out a first bypass return air inlet (832) and a first bypass air inlet (833). The dry end of the hood (8) has a second air inlet (84) and a second return air inlet (85), which are connected by a second circulating fan (861) to form a second circulating loop (86). The second circulating loop also leads out a second bypass return air inlet. 862) and the second bypass air inlet (863); the first bypass return air inlet (832) and the second bypass return air inlet (862) are connected to the dehumidification and cooling air duct (1) of the ultra-high temperature heat pump dehumidifier unit through a pipe, so that the hot and humid return air is dehumidified and heated by the ultra-high temperature heat pump dehumidifier unit; the output end of the drying and heating air duct (2) of the ultra-high temperature heat pump dehumidifier unit is connected to the first bypass air inlet (833) and the second bypass air inlet (863) through a pipe, so that the hot and dry air is delivered to the first circulation loop (83) and the second circulation loop (86) through the first bypass air inlet (833) and the second bypass air inlet (863) respectively.

8. The paper drying cylinder circulation system according to claim 7, characterized in that, The dehumidification and cooling air duct (1) is equipped with a waste heat recovery device (9) at its inlet, so that the hot and humid return air output from the first bypass return air port (832) and the second bypass return air port (862) passes through the waste heat recovery device (9) before entering the dehumidification and cooling air duct (1). The waste heat recovery device (9) is also equipped with a fresh air supply channel (91). The output end of the fresh air supply channel (91) is connected to the first circulation loop (83) and the second circulation loop (86) respectively, so that the outside fresh air is input from the fresh air supply channel (91) and absorbs the heat of the return air in the waste heat recovery device (9) to raise its temperature. The raised fresh air is then supplied to the first circulation loop (83) and the second circulation loop (86).

9. The paper drying cylinder circulation system according to claim 7, characterized in that, The first circulation loop (83) is further provided with a first air heater (834), and the second circulation loop (86) is further provided with a second air heater (864). The first air heater (834) and the second air heater (864) are respectively used to heat the hot dry air circulating in the first circulation loop (83) and the second circulation loop (86).

10. The paper drying cylinder circulation system according to claim 5, characterized in that, The drying cylinder (7) is connected to the water source evaporator (6) through a pipe, so that the steam condensate output by the drying cylinder (7) is delivered to the water source evaporator (6) for heating the refrigerant of the first evaporation module (31).

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