Energy-saving drying system

Abstract

The present invention discloses an energy-saving drying system, comprising a first heat exchanger, a second heat exchanger, a third heat exchanger and a fourth heat exchanger arranged in an outlet air duct, and also comprising a throttle, a compressor and a fan. The gas driven by the fan flows through the fourth heat exchanger, the second heat exchanger, the third heat exchanger and the first heat exchanger in sequence, and is finally discharged from the first heat exchanger. A throttle is arranged between the air outlet of the first heat exchanger and the air inlet of the second heat exchanger. The exhaust port of the compressor is connected to the air inlet of the first heat exchanger, the air intake port of the compressor is connected to the air outlet of the second heat exchanger, the third heat exchanger and the fourth heat exchanger are circularly connected, and a pump is arranged on the connecting pipeline between the third heat exchanger and the fourth heat exchanger.

Description

Technical Field

[0001] The invention belongs to the technical field of drying devices, and in particular relates to an energy-saving drying system. Background Art

[0002] A drying device is a device used in a drying room or a drying space. The drying device usually includes a first heat exchanger, a second heat exchanger, a fan and a compressor. The fan drives the air in the drying room or the drying space to the second heat exchanger. After the air contacts the second heat exchanger, it is cooled by the second heat exchanger, so that the water in the air is condensed and liquefied. The air further flows through the first heat exchanger, is heated and heated, and forms high-temperature and low-humidity air to be sent to the drying area. The refrigerant on the inside of the first heat exchanger is condensed to form a liquid refrigerant that flows through the throttle, and then flows into the second heat exchanger to be evaporated to form a low-pressure gas, which is sucked into its air inlet by the compressor, and then compressed into a high-temperature and high-pressure refrigerant by the compressor. Then, the high-temperature and high-pressure refrigerant enters the first heat exchanger again. After the first heat exchanger exchanges heat with the air flowing through its surface, the refrigerant inside is condensed into a liquid refrigerant, and then flows through the throttle, repeating the cycle.

[0003] Since the existing drying device only includes the above-mentioned structure, the drying device consumes a lot of energy, especially in pursuit of supply air with lower relative humidity, resulting in poor drying effect and low efficiency. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention aims to provide an energy-saving drying system.

[0005] According to one aspect of the present invention, an energy-saving drying system is provided, comprising a first heat exchanger, a second heat exchanger, a third heat exchanger and a fourth heat exchanger arranged in an outlet air duct, and also comprising a throttle, a compressor and a fan. The gas driven by the fan flows through the fourth heat exchanger, the second heat exchanger, the third heat exchanger and the first heat exchanger in sequence, and is finally discharged from the first heat exchanger. A throttle is arranged between the air outlet of the first heat exchanger and the air inlet of the second heat exchanger. The exhaust port of the compressor is connected to the air inlet of the first heat exchanger, the air intake port of the compressor is connected to the air outlet of the second heat exchanger, the third heat exchanger and the fourth heat exchanger are circularly connected, and a pump is arranged on the connecting pipeline between the third heat exchanger and the fourth heat exchanger.

[0006] In the present invention, the air driven by the fan first reaches the fourth heat exchanger. After the air contacts the fourth heat exchanger, the air can be pre-cooled, and then reaches the second heat exchanger. After being cooled by the second heat exchanger, the gas in the air is cooled, and the moisture in the air is liquefied and condensed. The third heat exchanger can pre-heat the air. In addition, the water in the fourth heat exchanger can be discharged into the third heat exchanger via a water pump, and the water in the third heat exchanger can be discharged into the fourth heat exchanger by itself, forming a cycle; the pre-heated air reaches the first heat exchanger and contacts the first heat exchanger. The first heat exchanger discharges the heated air, and the discharged air can dry objects. The air after drying the objects can be driven by the fan again into the air intake duct, forming a cycle. In addition, the gas after working in the first heat exchanger can be discharged into the second heat exchanger via a throttle, forming a cycle.

[0007] In the present invention, due to the addition of the fourth heat exchanger and the third heat exchanger, the air can be pre-cooled and pre-heated respectively, thereby improving the efficiency of the present invention, and the high-temperature and low-humidity air flow rate discharged is large, and a better drying effect can be achieved when the power of the compressor is reduced. Secondly, a water pump is used to drive water to flow between the fourth heat exchanger and the third heat exchanger, and different temperature differences can be designed to increase the heat exchange capacity of the third and fourth heat exchangers, that is, to improve the pre-cooling and pre-heating capabilities, to achieve better drying effects and more energy saving. Compared with conventional heat pipe technology, the water is driven to flow in the fourth heat exchanger and the third heat exchanger by a water pump and to exchange heat with the air flowing through their surfaces, and the temperature and temperature difference of the heat exchanger inlet and outlet are designed, which is more flexible and has a better heat exchange effect than heat pipe heat exchange, which can only form a unified condensation (or evaporation) temperature.

[0008] In some embodiments, a water receiving container is provided below the second heat exchanger, and a drain pipe is provided at the lower end of the water receiving container, and the drain pipe is used to drain the condensed water to the water inlet side of the pump or to the outside. Thus, the water receiving container can receive the condensed water falling from the second heat exchanger and drain it through the drain pipe.

[0009] In some embodiments, the air outlet duct is divided into a first air outlet duct and a second air outlet duct, the second heat exchanger, the third heat exchanger and the fourth heat exchanger are all arranged in the first air outlet duct, the first part of the first heat exchanger is located in the first air outlet duct, the second part is located in the second air outlet duct, a part of the gas driven by the fan enters the first air outlet duct, and the other part enters the second air outlet duct, wherein the refrigerant side inlet of the first heat exchanger is arranged in the first part of the first heat exchanger, the refrigerant outlet is arranged on the second part of the first heat exchanger, and the refrigerant flows from the first part of the first heat exchanger into the second part. Thus, by dividing the air outlet duct into the first air outlet duct and the second air outlet duct, the temperatures of the air discharged from the two ducts are different, and can be used to dry different objects.

[0010] In some embodiments, a fifth heat exchanger is further included, and the fifth heat exchanger is arranged in the second air outlet duct. The air in the second air outlet duct passes through the fifth heat exchanger and the second part of the first heat exchanger in sequence; one end of the fifth heat exchanger is arranged on the pipeline between the third heat exchanger and the fourth heat exchanger, forming a parallel or series connection, and the other end is connected to the inlet side of the pump, between the third heat exchanger, the fourth heat exchanger and the fifth heat exchanger.

[0011] In some embodiments, a sixth heat exchanger is further included, and the sixth heat exchanger is disposed in the air inlet duct or the air outlet duct, and the inlet of the sixth heat exchanger is connected to the drain pipe, and the outlet is connected to the outside. Thus, the sixth heat exchanger can further pre-cool the air, and at the same time, the sixth heat exchanger can also discharge the liquefied condensed water.

[0012] In some embodiments, a sixth heat exchanger is further included. The sixth heat exchanger is disposed in the air inlet duct or the air outlet duct. The inlet of the sixth heat exchanger is connected to the drain pipe, and the outlet is connected to the inlet side of the pump.

[0013] In some embodiments, a sixth heat exchanger and a seventh heat exchanger are also included, the sixth heat exchanger is arranged in the second air outlet duct, and the seventh heat exchanger is arranged in the first air outlet duct; the inlet of the sixth heat exchanger and the inlet of the seventh heat exchanger are both connected to the drain pipe; the outlet of the sixth heat exchanger and the outlet of the seventh heat exchanger are both connected to the inlet side of the pump, and at this time, the inlet of the sixth heat exchanger and the seventh heat exchanger are connected in parallel; or, the inlet of the sixth heat exchanger and the seventh heat exchanger are connected in series, the inlet of the sixth heat exchanger is connected to the drain pipe, the seventh heat exchanger is connected to the sixth heat exchanger, and the outlet of the seventh heat exchanger is connected to the inlet side of the pump, or, the inlet of the seventh heat exchanger and the sixth heat exchanger are connected in series, the inlet of the seventh heat exchanger is connected to the drain pipe, the sixth heat exchanger is connected to the seventh heat exchanger, and the outlet of the sixth heat exchanger is connected to the inlet side of the pump.

[0014] In some embodiments, a constant pressure water replenishment device is further included, and the water of the sixth heat exchanger reaches the constant pressure water replenishment device through the outlet and enters the pipeline between the third heat exchanger and the fourth heat exchanger; or the water of the sixth heat exchanger and the seventh heat exchanger reaches the constant pressure water replenishment device through the outlet and enters the pipeline between the third heat exchanger and the fourth heat exchanger. Thus, the constant pressure water replenishment device can replenish the third heat exchanger and the fourth heat exchanger with water at a certain pressure.

[0015] In some embodiments, the temperatures of the gas upstream and downstream of the fourth heat exchanger are Ta1 and Ta2, respectively, the other temperatures upstream and downstream of the third heat exchanger are Ta3 and Ta4, respectively, and the inlet and outlet temperatures of the liquid of the third heat exchanger are Tw1 and Tw2, respectively, and the following relationships are set: Ta1>Tw1>Ta4>Ta2>Tw2>Ta3, Ta1>Ta2+5°C, Ta3>Ta4+5°C, Ta1>Tw1>Ta1-3°C, Ta2>Tw2>Ta2-3°C. Thus, the limitations of these several heat exchange temperature differences can be used to achieve better heat exchange efficiency, and the cost problem can be taken into account, so as to achieve more pre-cooling and pre-heating heat exchange, making the baking of the present invention more energy-saving.

[0016] In some embodiments, heat storage material and phase change material are also included, and heat storage material or phase change material is also provided in the pipeline connecting the pump with the third heat exchanger and the fourth heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic structural diagram of an energy-saving drying system according to Embodiment 1 of the present invention;

[0018] Figure 2 This is a structural schematic diagram of an energy-saving drying system according to a second embodiment of the present invention;

[0019] Figure 3 This is a schematic structural diagram of an energy-saving drying system according to Embodiment 3 of the present invention;

[0020] Figure 4 This is a schematic structural diagram of an energy-saving drying system according to a fourth embodiment of the present invention;

[0021] Figure 5 This is a structural schematic diagram of an energy-saving drying system according to a fifth embodiment of the present invention;

[0022] Figure 6 This is a structural schematic diagram of an energy-saving drying system according to a sixth embodiment of the present invention;

[0023] Figure 7 This is a structural schematic diagram of an energy-saving drying system according to Embodiment 7 of the present invention;

[0024] Figure 8 This is a schematic structural diagram of an energy-saving drying system according to Embodiment 8 of the present invention;

[0025] Fig. 9 This is a structural schematic diagram of an energy-saving drying system according to Embodiment 9 of the present invention;

[0026] Fig.10 This is a schematic structural diagram of an energy-saving drying system according to a tenth embodiment of the present invention;

[0027] Fig.11This is a schematic structural diagram of an energy-saving drying system according to an eleventh embodiment of the present invention;

[0028] Fig.12 It is a structural schematic diagram of an energy-saving drying system according to the twelfth embodiment of the present invention.

[0029] In the figure: 1-first heat exchanger; 11-throttle; 12-exhaust duct; 121-first exhaust duct; 122-second exhaust duct; 2-second heat exchanger; 21-water container; 3-third heat exchanger; 31-pump; 4-fourth heat exchanger; 5-compressor; 6-fan; 61-intake duct; 7-sixth heat exchanger; 71-constant pressure water replenishment device; 8-sixth heat exchanger; 9-seventh heat exchanger. DETAILED DESCRIPTION

[0030] 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.

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0032] Implementation Benefit 1:

[0033] like Figure 1 As shown, an energy-saving drying system includes a first heat exchanger 1, a second heat exchanger 2, a third heat exchanger 3 and a fourth heat exchanger 4 arranged in an outlet air duct 12, and also includes a throttle 11, a compressor 5 and a fan 6 arranged in an inlet air duct 61.

[0034] The air driven by the fan 6 flows through the fourth heat exchanger 4, the second heat exchanger 2, the third heat exchanger 3 and the first heat exchanger 1 in sequence, and is finally discharged from the first heat exchanger 1. A throttle 11 is installed between the air outlet of the first heat exchanger 1 and the air inlet of the second heat exchanger 2. The exhaust port of the compressor 5 can be connected to the air inlet of the first heat exchanger 1, and the air intake port of the compressor 5 is connected to the air outlet of the second heat exchanger 2. The outlet of the third heat exchanger 3 is connected to the inlet of the fourth heat exchanger 4, and the inlet of the third heat exchanger 3 is connected to the outlet of the fourth heat exchanger 4. Furthermore, a (water) pump 31 is provided on the connecting pipeline between the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4.

[0035] The above connection methods are all connected through pipelines (i.e. pipes).

[0036] like Figure 1 As shown, in this embodiment, a water receiving container 21 is installed under the second heat exchanger 2, and a drain pipe is provided at the lower end of the water receiving container 21. The water receiving container 21 can receive the condensed water falling from the second heat exchanger 2 and discharge it through the drain pipe.

[0037] Embodiment 2:

[0038] Based on the first embodiment, Figure 2 As shown, in this embodiment, the air outlet duct 12 is divided into two, that is, the air outlet duct 12 is divided into a first air outlet duct 121 and a second air outlet duct 122, the fourth heat exchanger 4, the second heat exchanger 2 and the third heat exchanger 3 are arranged in the first air outlet duct 121, half of the first heat exchanger 1 is arranged at the second air outlet duct (port), and the other half is arranged at the first air outlet duct (port), and the remaining structure is exactly the same as that of the first embodiment, and will not be repeated. Through this arrangement, the gas temperatures discharged from the first air outlet duct (port) and the second air outlet duct (port) are different, which can meet different needs.

[0039] Embodiment three:

[0040] Based on the second embodiment, Figure 3 As shown, in this embodiment, a fifth heat exchanger 7 is added, the outlet of the third heat exchanger 3 is connected to the inlet of the fourth heat exchanger 4, the outlet of the fourth heat exchanger 4 is connected to the inlet of the fifth heat exchanger 7, the outlet of the fifth heat exchanger 7 is connected to the inlet of the third heat exchanger 3, and the pump 31 is arranged between the outlet of the fifth heat exchanger 7 and the inlet of the third heat exchanger 3. The remaining structure is exactly the same as that of the second embodiment and will not be repeated here.

[0041] Embodiment 4: Based on Embodiment 2, Figure 4 As shown, in this embodiment, a fifth heat exchanger 7 is added, the inlet of the fifth heat exchanger 7 is connected to the pipeline (the outlet of the third heat exchanger 3 and the inlet of the fourth heat exchanger 4 are connected), the outlet of the fifth heat exchanger 7 is connected to the pipeline (the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4 are connected), and the remaining structure is exactly the same as that of the second embodiment and will not be repeated.

[0042] Embodiment 5: Based on the implementation of benefit 1, Figure 5 As shown, in this embodiment, a constant pressure water replenishment device 71 is added, the drain pipe is connected to the pipeline (connecting the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4), the constant pressure water replenishment device 71 is arranged between the drain pipe and the pipeline (connecting the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4), and the constant pressure water replenishment device 71 is located upstream of the pump 31, and the remaining structure is exactly the same as that of the first embodiment and will not be repeated.

[0043] Embodiment 6: Based on Embodiment 2, Figure 6As shown, in this embodiment, a constant pressure water replenishment device 71 is added, the drain pipe is connected to the pipeline (connecting the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4), the constant pressure water replenishment device 71 is arranged between the drain pipe and the pipeline (connecting the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4), and the constant pressure water replenishment device 71 is located upstream of the pump 31, and the remaining structure is exactly the same as that of the second embodiment and will not be repeated.

[0044] Embodiment 7: Based on Embodiment 5, Figure 7 As shown, in this embodiment, a sixth heat exchanger 8 is added, and the sixth heat exchanger 8 is arranged in the air intake duct 61. The inlet of the sixth heat exchanger 8 is connected to the drain pipe, and the outlet is connected to the constant pressure water replenishment device 71. The remaining structure is exactly the same as that of the fifth embodiment and will not be repeated.

[0045] Embodiment 8: Based on Embodiment 3, Figure 8 As shown, in the present embodiment, a sixth heat exchanger 8 and a constant-pressure water replenishment device 71 are added, the sixth heat exchanger 8 is arranged in the air intake duct 61, the inlet of the sixth heat exchanger 8 is connected to the drain pipe, and the outlet is connected to one end of the constant-pressure water replenishment device 71, and the other end of the constant-pressure water replenishment device 71 is connected to the pipeline (connecting the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4), and the remaining structure is exactly the same as that of the third embodiment and will not be repeated.

[0046] Embodiment 9: Based on Embodiment 4, Fig. 9 As shown, in the present embodiment, a sixth heat exchanger 8 and a constant-pressure water replenishment device 71 are added, the sixth heat exchanger 8 is arranged in the air intake duct 61, the inlet of the sixth heat exchanger 8 is connected to the drain pipe, and the outlet is connected to one end of the constant-pressure water replenishment device 71, and the other end of the constant-pressure water replenishment device 71 is connected to the pipeline (connecting the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4), and the remaining structure is exactly the same as that of the fourth embodiment and will not be repeated.

[0047] Embodiment 10: Based on Embodiment 4, Fig.10 As shown, in the present embodiment, a sixth heat exchanger 8, a seventh heat exchanger 9 and a constant-pressure water replenishment device 71 are added, the sixth heat exchanger 8 is arranged in the second air outlet duct 122, the seventh heat exchanger 9 is arranged in the first air outlet duct 121, the inlet of the sixth heat exchanger 8 and the inlet of the seventh heat exchanger 9 are both connected to the drain pipe; the outlet of the sixth heat exchanger 8 and the outlet of the seventh heat exchanger 9 are both connected to one end of the constant-pressure water replenishment device 71, and the other end of the constant-pressure water replenishment device 71 is connected to the pipeline (connecting the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4).

[0048] Embodiment 11: Based on Embodiment 1, Fig.11 As shown, a sixth heat exchanger 8 is added, the inlet of the sixth heat exchanger 8 is connected to the drain pipe, and the outlet is connected to the outside.

[0049] Embodiment 12: Based on Embodiment 2, Fig.12 As shown, a sixth heat exchanger 8 and a constant-pressure water replenishment device 71 are added, the inlet of the sixth heat exchanger 8 is connected to the drain pipe, and the outlet is connected to the constant-pressure water replenishment device 71, and the constant-pressure water replenishment device 71 is connected to the pipeline (connecting the inlet of the third heat exchanger 3 and the outlet of the fourth heat exchanger 4).

[0050] In summary, it can be known that in the present invention, a fifth heat exchanger 7 can be added, the fifth heat exchanger 7 can be arranged in the second air outlet channel, and the fifth heat exchanger 7 can be connected to the fourth heat exchanger 4 in series or parallel, as long as the water in the fifth heat exchanger 7 can enter the pipeline between the fourth heat exchanger 4 and the third heat exchanger 3; a sixth heat exchanger 8 and a constant pressure water replenishment device 71 can also be added, and the condensed water at the second heat exchanger 2 can enter the sixth heat exchanger 8 and circulate to the pipeline of the third heat exchanger 3 and the fourth heat exchanger 4 through the constant pressure water replenishment device 71. Of course, the water in the sixth heat exchanger 8 can also be directly discharged to the outside. Similarly, a seventh heat exchanger 9 can also be added, and the function of the seventh heat exchanger 9 is the same as that of the sixth heat exchanger 8.

[0051] In this embodiment, the temperature of the gas upstream and downstream of the fourth heat exchanger is Ta1, Ta2, the other temperatures upstream and downstream of the third heat exchanger are Ta3, Ta4, and the inlet and outlet temperatures of the liquid of the third heat exchanger are Tw1, Tw2, respectively, and the following relationships are set: Ta1>Tw1>Ta4>Ta2>Tw2>Ta3, Ta1>Ta2+5℃, Ta3>Ta4+5℃, Ta1>Tw1>Ta1-3℃, Ta2>Tw2>Ta2-3℃. Therefore, the limitations of these several heat exchange temperature differences can be used to make the heat exchange efficiency better, and the cost problem can be taken into account, so as to achieve more pre-cooling and pre-heating heat exchange, making the baking of the present invention more energy-saving.

[0052] In this embodiment, heat storage material and phase change material are also included, and heat storage material or phase change material is also provided in the pipeline connecting the pump with the third heat exchanger and the fourth heat exchanger.

[0053] In the present invention, the air driven by the fan first reaches the fourth heat exchanger. After the air contacts the fourth heat exchanger, the air can be pre-cooled, and then reaches the second heat exchanger. After being cooled by the second heat exchanger, the gas in the air is cooled, and the moisture in the air is liquefied and condensed. The third heat exchanger can pre-heat the air. In addition, the water in the fourth heat exchanger can be discharged into the third heat exchanger via a water pump, and the water in the third heat exchanger can be discharged into the fourth heat exchanger by itself, forming a cycle; the pre-heated air reaches the first heat exchanger and contacts the first heat exchanger. The first heat exchanger discharges the heated air, and the discharged air can dry objects. The air after drying the objects can be driven by the fan again into the air intake duct, forming a cycle. In addition, the gas after working in the first heat exchanger can be discharged into the second heat exchanger via a throttle, forming a cycle.

[0054] In the present invention, due to the addition of the fourth heat exchanger and the third heat exchanger, the air can be pre-cooled and pre-heated respectively, thereby improving the efficiency of the present invention, and the high-temperature and low-humidity air flow rate discharged is large, and a better drying effect can be achieved when the power of the compressor is reduced. Secondly, a water pump is used to drive water to flow between the fourth heat exchanger and the third heat exchanger, and different temperature differences can be designed to increase the heat exchange capacity of the third and fourth heat exchangers, that is, to improve the pre-cooling and pre-heating capabilities, to achieve better drying effects and more energy saving. Compared with conventional heat pipe technology, the water is driven to flow in the fourth heat exchanger and the third heat exchanger by a water pump and to exchange heat with the air flowing through their surfaces, and the temperature and temperature difference of the heat exchanger inlet and outlet are designed, which is more flexible and has a better heat exchange effect than heat pipe heat exchange, which can only form a unified condensation (or evaporation) temperature.

[0055] The present invention is not limited to the above-mentioned optional implementation modes. Anyone can derive other various forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, all technical solutions that fall within the scope defined by the claims of the present invention fall within the protection scope of the present invention.

Claims

1. An energy-saving drying system, characterized in that: The invention comprises a first heat exchanger (1), a second heat exchanger (2), a third heat exchanger (3) and a fourth heat exchanger (4) arranged in an air outlet duct (12), and further comprises a throttle (11), a compressor (5) and a fan (6); the gas driven by the fan (6) flows through the fourth heat exchanger (4), the second heat exchanger (2), the third heat exchanger (3) and the first heat exchanger (1) in sequence, and is finally discharged from the first heat exchanger (1); a throttle (11) is arranged between the air outlet of the first heat exchanger (1) and the air inlet of the second heat exchanger (2); the exhaust port of the compressor (5) is connected to the air inlet of the first heat exchanger (1); the air intake port of the compressor (5) is connected to the air intake port of the second heat exchanger ( The third heat exchanger (3) and the fourth heat exchanger (4) are connected to each other in a circulation manner, and a pump (31) is provided on the connecting pipeline between the third heat exchanger (3) and the fourth heat exchanger (4); a water receiving container (21) is provided below the second heat exchanger (2), and a drain pipe is provided at the lower end of the water receiving container (21); the air outlet duct (12) is divided into a first air outlet duct (121) and a second air outlet duct (122); the second heat exchanger (2), the third heat exchanger (3) and the fourth heat exchanger (4) are all provided in the first air outlet duct (121); the first part of the first heat exchanger (1) is located in the first air outlet duct (121), and the second part is located in the second air outlet duct (122); In the air outlet duct (122), part of the gas driven by the fan (6) enters the first air outlet duct (121), and the other part enters the second air outlet duct (122), wherein the refrigerant side inlet of the first heat exchanger (1) is arranged in the first part of the first heat exchanger (1), and the refrigerant outlet is arranged on the second part of the first heat exchanger (1), and the refrigerant flows from the first part of the first heat exchanger (1) into the second part; and further comprises a fifth heat exchanger (7), wherein the fifth heat exchanger (7) is arranged in the second air outlet duct (122), and the air in the second air outlet duct (122) passes through the fifth heat exchanger (7) and the second part of the first heat exchanger (1) in sequence; the fifth heat exchanger (7) One end of the heat exchanger (12) is arranged on the pipeline between the third heat exchanger (3) and the fourth heat exchanger (4), forming a parallel or series connection, and the other end is connected to the inlet side of the pump (31); it also includes a sixth heat exchanger (8) and a seventh heat exchanger (9), the sixth heat exchanger (8) is arranged in the second air outlet duct (122), and the seventh heat exchanger (9) is arranged in the first air outlet duct (121); the inlet of the sixth heat exchanger (8) and the inlet of the seventh heat exchanger (9) are both connected to the drain pipe; the outlet of the sixth heat exchanger (8) and the outlet of the seventh heat exchanger (9) are both connected to the inlet side of the pump (31), and the inlet of the sixth heat exchanger (8) and the seventh heat exchanger (9) are connected in parallel;Alternatively, the inlet of the sixth heat exchanger (8) and the seventh heat exchanger (9) are connected in series, the inlet of the sixth heat exchanger (8) is connected to the drain pipe, the seventh heat exchanger (9) is connected to the sixth heat exchanger (8), and the outlet of the seventh heat exchanger (9) is connected to the inlet side of the pump (31); Alternatively, the inlet of the seventh heat exchanger (9) and the sixth heat exchanger (8) are connected in series, the inlet of the seventh heat exchanger (9) is connected to the drain pipe, the sixth heat exchanger (8) is connected to the seventh heat exchanger (9), and the outlet of the sixth heat exchanger (8) is connected to the inlet side of the pump (31). ; 2. The energy-saving drying system according to claim 1, characterized in that: The apparatus further comprises a constant-pressure water replenishment device (71), wherein water from the sixth heat exchanger (8) reaches the constant-pressure water replenishment device (71) via the outlet and enters the pipeline between the third heat exchanger (3) and the fourth heat exchanger (4); or water from the sixth heat exchanger (8) and the seventh heat exchanger (9) reaches the constant-pressure water replenishment device (71) via the outlet and enters the pipeline between the third heat exchanger (3) and the fourth heat exchanger (4).

3. The energy-saving drying system according to claim 2, characterized in that: The temperatures of the gases upstream and downstream of the fourth heat exchanger are Ta1 and Ta2 respectively, the temperatures of the upstream and downstream of the third heat exchanger are Ta3 and Ta4 respectively, and the liquid inlet and outlet temperatures of the third heat exchanger are Tw1 and Tw2 respectively, and the following relationship is set: Ta1>Tw1>Ta4>Ta2>Tw2>Ta3, Ta1>Ta2+5℃, Ta3>Ta4+5℃, Ta1>Tw1>Ta1-3℃, Ta2>Tw2>Ta2-3℃.

4. The energy-saving drying system according to claim 3, characterized in that: It also includes heat storage material and phase change material, and the pipeline connecting the pump (31) and the third heat exchanger and the fourth heat exchanger is also provided with heat storage material or phase change material.

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