Multi-stage heat pump drying unit parallel system

Abstract

The present invention provides a multi-stage heat pump drying unit parallel system, including a plurality of dryers arranged in parallel and a main engine room shared by the plurality of dryers, the dryers are divided into a pair of drying chambers, a return air chamber arranged between the pair of drying chambers, and a buffer chamber, the side walls of the return air chamber adjacent to each drying chamber are provided with a shunt structure connected to the drying chamber, a circulating fan and a condenser are arranged in the return air chamber, a return air valve and an exhaust air valve are arranged on the side walls adjacent to the return air chamber and the buffer chamber, respectively, a first fresh air valve is arranged on the top wall of the buffer chamber; the exhaust air valve is connected to the exhaust duct of the main engine room through the buffer chamber, and the return air valve is directly connected to the main engine room through the buffer chamber; a plurality of heat pump units are arranged in the main engine room, and a second fresh air valve and a dehumidification valve fan assembly are arranged on the side walls of the main engine room. The present invention can solve the technical problems that the performance of the heat pump system is low under low temperature conditions in cold areas in winter and the energy efficiency of the closed-loop circulation heat pump drying system is relatively low under high temperature conditions in summer.

Description

Technical Field

[0001] The invention relates to the technical field of heat pump drying technology, and in particular to a multi-stage heat pump drying unit parallel system. Background Art

[0002] The heat pump system can recycle waste heat from the drying process, and it has the advantages of low energy consumption, high temperature and humidity control accuracy, and high drying efficiency. In the cold northern regions, the heat pump drying system is currently mainly a semi-open system, which has significant advantages in summer conditions, but in cold winter regions, the evaporation temperature of the heat pump system is too low, reducing the performance of the heat pump system, and even failing to operate normally. Summary of the invention

[0003] The embodiment of the present invention provides a multi-stage heat pump drying unit parallel system to solve the technical problems of low performance of the heat pump system under low temperature conditions in cold areas in winter and relatively low energy efficiency of the closed-loop heat pump drying system under high temperature conditions in summer.

[0004] The embodiment of the present invention provides a multi-stage heat pump drying unit parallel system, comprising a plurality of dryers arranged in parallel and a main engine room arranged on one side of the plurality of dryers and shared by the plurality of dryers, each of the dryers being divided into a pair of drying chambers, a return air chamber arranged between the pair of drying chambers, and a buffer chamber separated from the pair of drying chambers and the return air chambers and located at the top of the pair of drying chambers and the return air chambers, a feeding door being arranged on the end side wall of the drying chamber away from the main engine room, a shunt structure being communicated with the drying chamber being arranged on the side wall of the return air chamber adjacent to each of the drying chambers, a circulating fan and a buffer chamber for heating the return air chamber being arranged in the return air chamber A condenser for hot circulating air, the side walls of the return air chamber and the buffer chamber adjacent to each other are respectively provided with a return air valve and an exhaust air valve, the return air chamber is provided with a first partition separating the return air valve and the exhaust air valve, the top wall of the buffer chamber is provided with a first fresh air valve; the exhaust valve is connected to the exhaust duct of the main engine room through the buffer chamber, and the return air valve is directly connected to the main engine room through the buffer chamber; a heat pump unit corresponding to each dryer is provided in the main engine room, a second fresh air valve is provided on one side wall of the main engine room, a fresh air duct connected to the second fresh air valve is provided in the main engine room, and a dehumidification valve fan assembly is provided on the other side wall of the main engine room.

[0005] According to one embodiment of the present invention, heat storage material is provided in the main engine room, and each of the heat pump units includes an evaporator and the condenser provided in the return air room, and the evaporator is provided in the main engine room.

[0006] According to one embodiment of the present invention, the return air chamber is provided with a temperature and humidity sensor.

[0007] According to one embodiment of the present invention, the return air chamber is provided with a pair of exhaust valves spaced apart along its length direction, which are a first exhaust valve and a second exhaust valve, respectively. The first exhaust valve and the second exhaust valve are respectively arranged on both sides of the condenser, and a guide plate is provided at each exhaust valve in the return air chamber.

[0008] According to one embodiment of the present invention, the return air chamber is provided with a pair of return air valves spaced apart along its length direction, which are a first return air valve and a second return air valve, respectively. The first return air valve and the second return air valve are respectively arranged on both sides of the condenser; a pair of the exhaust valves and a pair of the return air valves are separated by the first partition plate.

[0009] According to one embodiment of the present invention, the circulation fan is a forward and reverse rotating fan;

[0010] The dehumidification valve and fan assembly includes an independently controlled dehumidification valve and a fan;

[0011] The flow splitting structure includes a flow splitting plate and flow splitting blades.

[0012] According to one embodiment of the present invention, the main engine room and the plurality of dryers are separated by a second partition, the second fresh air valve is arranged near the top of the second partition, and the fresh air duct is fixed on the second partition.

[0013] According to an embodiment of the present invention, an inspection port is provided at a position of the second partition corresponding to each of the dryers.

[0014] According to an embodiment of the present invention, the heat pump unit is provided with a condensate discharge outlet, and the condensate discharge outlet is connected to an underground drainage system.

[0015] According to one embodiment of the present invention, the main engine room is provided with inspection doors on two opposite sides along the length direction thereof.

[0016] A multi-stage heat pump drying unit parallel system provided in an embodiment of the present invention comprises a plurality of dryers arranged in parallel and a main engine room arranged on one side of the plurality of dryers and shared by the plurality of dryers, each of the dryers being divided into a pair of drying chambers, a return air chamber arranged between the pair of drying chambers, and a buffer chamber which is separated from the pair of drying chambers and the return air chambers and is located on the top of the pair of drying chambers and the return air chambers, a feeding door is provided on the end side wall of the drying chamber away from the main engine room, the side wall of the return air chamber adjacent to each of the drying chambers is provided with a diversion structure connected to the drying chamber, a circulating fan and a condenser for heating circulating air are provided in the return air chamber, a return air valve and an exhaust air valve are provided in the side wall of the return air chamber adjacent to the buffer chamber, a first partition separating the return air valve from the exhaust air valve is provided in the return air chamber, and the buffer chamber The top wall is provided with a first fresh air valve; the exhaust valve is connected to the exhaust duct of the main engine room through the buffer chamber, and the return air valve is directly connected to the main engine room through the buffer chamber; a heat pump unit corresponding to each dryer is provided in the main engine room, a second fresh air valve is provided on one side wall of the main engine room, a fresh air duct connected to the second fresh air valve is provided in the main engine room, and a dehumidification valve fan assembly is provided on the other side wall of the main engine room; it can not only realize the semi-open and closed-circuit coupling operation of the system, but also solve the technical problems of low performance of the heat pump system under low temperature conditions in cold areas in winter and relatively low energy efficiency of the closed-circuit circulation heat pump drying system under high temperature conditions in summer; and multiple dryers share one main engine room to realize the sharing of waste heat from different drying units. When a dryer is in the moisturizing stage, its heat pump unit can use the waste heat of other dryers. In addition, the operation mode of summer working conditions is designed in this embodiment, which can realize all-weather operation conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 1 is a schematic diagram of a top view of a multi-stage heat pump drying unit parallel system according to an embodiment of the present invention, showing the flow direction of the airflow in a forward rotation direction;

[0019] Figure 2 is a schematic diagram of a top view of a multi-stage heat pump drying unit parallel system according to an embodiment of the present invention, showing the direction of airflow reversal;

[0020] Figure 3 yes Figure 1 Schematic cross-sectional view of AA in the figure;

[0021] Figure 4 yes Figure 2 Schematic cross-sectional view of AA in the figure;

[0022] Figure 5 yes Figure 1 Schematic diagram of the cross-section of BB.

[0023] Reference numerals:

[0024] 1. Heat pump unit; 2. Condenser; 3. Circulation fan; 4. First exhaust valve; 5. Second exhaust valve; 6. First return valve; 7. Second return valve; 8. First fresh air valve; 9. Exhaust duct; 10. Second fresh air valve; 11. Fresh air duct; 12. Dehumidification valve fan assembly; 13. Inspection door; 14. Feed door; 15. Diversion structure; 16. Drying chamber; 17. Return air chamber; 18. Main machine room; 19. Buffer chamber; 20. First partition; 21. Guide plate. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are 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.

[0026] Combine the following Figure 1-Figure 5 A multi-stage heat pump drying unit parallel system (referred to as a heat pump system in this embodiment) according to an embodiment of the present invention is described.

[0027] like Figure 1 and Figure 2 As shown, a multi-stage heat pump drying unit parallel system provided by an embodiment of the present invention includes a plurality of dryers arranged in parallel and a main engine room 18 arranged on one side of the plurality of dryers and shared by the plurality of dryers, that is, in this embodiment, one main engine room 18 is provided, and the plurality of dryers share the one main engine room 18. In this embodiment, the plurality of dryers arranged in parallel are arranged in parallel.

[0028] Specifically, Figure 1 and Figure 2 As shown, combined with Figure 3 to Figure 4Each of the dryers is divided into a pair of drying chambers 16, a return air chamber 17 disposed between the pair of drying chambers 16, and a buffer chamber 19 which is separated from the pair of drying chambers 16 and the return air chamber 17 and is located on the top of the pair of drying chambers 16 and the return air chamber 17. Specifically, if the height direction of the dryer is used as a reference, the pair of drying chambers 16 and the return air chamber 17 are located on the same layer, and the buffer chamber 19 is located on the upper layer of the drying chambers 16 and the return air chamber 17. In other words, the dryer is divided into upper and lower layers, the pair of drying chambers 16 and the return air chamber 17 are located on the lower layer, and the buffer chamber 19 is located on the upper layer.

[0029] Furthermore, the return air chamber 17 and the pair of drying chambers 16 are separated by a partition, and the buffer chamber 19 and the return air chamber 17 and the pair of drying chambers 16 are also separated by a partition.

[0030] Among them, a feed door 14 is provided on the end side wall of the drying chamber 16 away from the main engine chamber 18, and the end where the drying chamber 16 is connected to the main engine chamber 18 is taken as the head end, and the feed door 14 is arranged on the tail end side wall of the drying chamber 16, so as to facilitate the material to be dried to enter the drying chamber 16 from the feed door 14 for drying.

[0031] Among them, the side walls of the return air chamber 17 adjacent to each of the drying chambers 16 are provided with a diversion structure 15 connected to the drying chamber 16. Specifically, the diversion structure 15 may include a diversion plate and a diversion blade. The diversion plate is provided with flow holes. The diversion blades are arranged relative to the diversion plate, which can accelerate the circulation of airflow and facilitate the uniform distribution of air entering the drying chamber 16. In order to ensure the uniformity of gas circulation, the diversion structure 15 can be set at both ends of the side walls of the return air chamber 17 adjacent to each of the drying chambers 16.

[0032] In this embodiment, a heat pump unit 1 corresponding to each dryer is provided in the main engine room 18. The heat pump unit 1 includes a compressor and a condenser 2 and an evaporator that form a refrigeration circuit with the compressor. In this embodiment, the condenser 2 is used for heating and the evaporator is used for cooling. A circulating fan 3 and a condenser 2 for heating circulating air are provided in the return air chamber 17. The condenser 2 is the condenser 2 of the heat pump unit 1, and the evaporator is still provided in the main engine room 18.

[0033] In this embodiment, the side walls adjacent to the return air chamber 17 and the buffer chamber 19 are respectively provided with a return air valve and an exhaust valve, and a first partition plate 20 is provided in the return air chamber 17 to separate the return air valve and the exhaust valve; the return air valve and the buffer chamber 19 form a return air cavity, and the exhaust air valve and the buffer chamber 19 form an exhaust cavity, and the exhaust valve is connected to the exhaust duct 9 of the main engine room 18 through the buffer chamber 19 (i.e., the exhaust cavity), and the exhaust air of the return air chamber 17 is introduced into the main engine room 18 through the exhaust duct 9, and the return air valve is directly connected to the main engine room 18 through the buffer chamber 19 (i.e., the return air cavity).

[0034] In this embodiment, a first fresh air valve 8 is provided on the top wall of the buffer chamber 19. It can be understood that the first fresh air valve 8 is used to introduce fresh air into the return air chamber 17 when needed.

[0035] In this embodiment, Figure 5 As shown, a second fresh air valve 10 is provided on one side wall of the main engine room 18, and a fresh air duct 11 connected to the second fresh air valve 10 is provided in the main engine room 18, and fresh air is introduced into the main engine room 18 through the second fresh air valve 10, and the fresh air is introduced through the fresh air duct 11; a dehumidification valve fan assembly 12 is provided on another side wall of the main engine room 18, which is used to discharge the gas in the main engine room 18 into the environment. The second fresh air valve 10 and the fresh air duct 11 are operated in conjunction with the dehumidification valve fan assembly 12, and when the drying room 16 is in the moisturizing stage or the high temperature summer working condition, the second fresh air valve 10 and the dehumidification valve fan assembly 12 can be opened at the same time.

[0036] In this embodiment, the temperature of the drying chamber 16 is adjusted by using the heat pump unit 1, which can be controlled by adjusting the frequency of the compressor or starting and stopping the compressor.

[0037] This embodiment adopts a coupled operation mode of closed-loop and semi-open cycles; specifically, the closed-loop operation mode is that the exhaust valve discharges the heated air in the return air chamber 17 into the main engine room 18 through the buffer chamber 19, and the air processed in the main engine room 18 returns to the return air chamber 17 through the return air valve.

[0038] A semi-open operation mode is specifically as follows: the exhaust valve discharges the heated air in the return air chamber 17 into the main engine room 18 through the buffer chamber 19, and then discharges it into the environment through the dehumidification valve fan assembly 12 of the main engine room 18, and then replenishes fresh air into the return air chamber 17 through the first fresh air valve 8 to ensure stable air pressure.

[0039] Another semi-open type is as follows: the exhaust valve discharges the heated air from the return air chamber 17 into the main engine room 18 through the buffer chamber 19, and then discharges it into the environment through the dehumidification valve fan assembly 12 of the main engine room 18, and then introduces fresh air into the main engine room 18 from the second fresh air valve 10.

[0040] This embodiment solves the technical problems of low performance of the heat pump system under low temperature conditions in cold areas in winter and relatively low energy efficiency of the closed-loop heat pump drying system under high temperature conditions in summer.

[0041] This embodiment utilizes the parallel operation mode of multiple heat pump drying units, and the heat pump units 1 of multiple heat pump drying units share a main engine room 18. Multiple dryers share a main engine room 18 to achieve sharing of waste heat from different drying units. When a dryer is in the moisturizing stage, its heat pump unit 1 can utilize the waste heat of other dryers.

[0042] According to one embodiment of the present invention, a heat storage material may be provided in the main engine room 18 to regulate the temperature of the main engine room 18 during the drying process. When the temperature in the main engine room 18 is relatively low, the heat storage material releases heat. When the temperature in the main engine room 18 is relatively high, the heat storage material absorbs heat. In addition, when the drying material has no strict requirements on humidity, the opening of the exhaust valve and the return air valve can realize the control of the temperature of the main engine room 18; when the drying material has strict requirements on humidity, the heat storage material in the main engine room 18 can be used to realize the temperature control of the main engine room 18.

[0043] According to an embodiment of the present invention, the return air chamber 17 is provided with a temperature and humidity sensor to provide a reference for regulating the heat pump unit 1 and the opening angles of each air valve.

[0044] According to one embodiment of the present invention, the return air chamber 17 is provided with a pair of exhaust valves spaced apart along its length direction, namely, a first exhaust valve 4 and a second exhaust valve 5, and the first exhaust valve 4 and the second exhaust valve 5 are provided on both sides of the condenser 2 to facilitate uniform exhaust. In order to introduce the air of the return air chamber 17 into the buffer chamber 19, a guide plate 21 is provided in the return air chamber 17 at each exhaust valve.

[0045] According to an embodiment of the present invention, the return air chamber 17 is provided with a pair of return air valves spaced apart along its length direction, namely, a first return air valve 6 and a second return air valve 7, and the first return air valve 6 and the second return air valve 7 are provided on both sides of the condenser 2 to facilitate the uniformity of the return air. The pair of exhaust valves and the pair of return air valves are separated by the first partition plate 20, so that the return air and the exhaust air do not affect each other.

[0046] According to one embodiment of the present invention, the circulating fan 3 is a forward and reverse rotating fan, which can make the entire circulating airflow rotate forward or reverse, thereby solving the problem of uneven drying of materials in the drying chamber 16 and improving the drying efficiency.

[0047] In one embodiment, the dehumidification valve-fan assembly 12 includes an independently controlled dehumidification valve and a fan, that is, the dehumidification valve can be opened to close the fan, or the dehumidification valve and the fan can be opened, and the opening degree of the dehumidification valve is adjustable.

[0048] This embodiment further includes a control device, which is connected to the exhaust valve, the circulation fan 3 and the heat pump unit 1.

[0049] According to one embodiment of the present invention, the main engine room 18 and the plurality of dryers are separated by a second partition. To facilitate the installation of the second fresh air valve 10 and the fresh air duct 11, the second fresh air valve 10 is arranged near the top of the second partition, and the fresh air duct 11 is fixed on the second partition.

[0050] According to one embodiment of the present invention, an inspection port is provided at a position of the second partition plate corresponding to each of the dryers, so as to facilitate the inspection or maintenance of each dryer.

[0051] According to one embodiment of the present invention, the heat pump unit 1 is provided with a condensate discharge outlet, which is connected to an underground drainage system and is used to discharge the condensate into the underground drainage system to prevent the condensate from accumulating in the main engine room 18 .

[0052] According to one embodiment of the present invention, the main engine room 18 is provided with inspection doors 13 on two opposite sides along the length direction thereof, so as to facilitate the inspection or maintenance of the main engine room 18 .

[0053] The operation modes of the heat pump system in winter and summer are described in detail below with reference to the accompanying drawings.

[0054] The preferred drying mode for low temperature environment in winter:

[0055] Figure 1 and Figure 3 The process of the heat pump system airflow forward rotation is described. First, the air in the drying chamber 16 that exchanges heat and mass with the material enters the return air chamber 17 through the diversion structure 15 (near the side of the feed door 14). A part of the air enters the buffer chamber 19 through the guide plate 21 and the exhaust valve 4, and then enters the main engine room 18 through the exhaust duct 9. In the main engine room 18, it is cooled and dehumidified by the heat pump unit 1. This part of the air can be discharged to the environment through the dehumidification valve fan assembly 12 of the main engine room 18 (it is recommended to only open the dehumidification valve and close the fan) When the dehumidification valve fan assembly 12 is discharged to the environment, it is necessary to open the first fresh air valve 8 to replenish fresh air, and also return to the return air chamber 17 through the first return air valve 6, or this part of the air directly returns to the return air chamber 17 through the first return air valve 6 and mixes with another part of the air in the return air chamber 17. The mixed air is discharged into the condenser 2 through the circulation fan 3, and the mixed air is heated with equal humidity. The heated air is discharged into the drying chamber 16 through the diversion structure 15, and heat and mass exchange is performed with the material in the drying chamber 16.

[0056] Figure 2 and Figure 4The flow of airflow reversal of the system is described. First, the air in the drying chamber 16 that exchanges heat and mass with the material enters the return air chamber 17 through the diversion structure 15 (close to the side of the main engine room 18). A part of the air enters the buffer chamber 19 through the guide plate 21 and the first exhaust valve 4, and then enters the main engine room 18 through the exhaust duct 9. In the main engine room 18, it is cooled and dehumidified by the heat pump unit 1. This part of the air can be discharged to the circulating air through the dehumidification valve fan assembly 12 of the main engine room 18 (it is recommended to only open the dehumidification valve and close the fan) When the dehumidification valve fan assembly 12 is discharged to the environment, it is necessary to open the first fresh air valve 8 to replenish fresh air, and return it to the return air chamber 17 through the second return air valve 7, or this part of the air directly returns to the return air chamber 17 through the second return air valve 7 and mixes with another part of the air in the return air chamber 17. The mixed air enters the condenser 2 and is heated with equal humidity. The heated air is discharged into the air supply port through the circulation fan 3, and then discharged into the drying chamber 16 through the diversion structure 15, and exchanges heat and mass with the material in the drying chamber 16.

[0057] The preferred drying mode for summer conditions:

[0058] Figure 5 The arrangement of the internal pipelines of the main engine room 18 is described. The second fresh air valve 10 is arranged on the top of the main engine room 18. The second fresh air valve 10 is connected to the fresh air duct 11 of the main engine room 18. The exhaust duct 9 is close to the fresh air duct 11. One side of the exhaust duct 9 is connected to the exhaust side of the buffer room 19. A return air port is arranged on the right side of the exhaust duct 9, which is the interface connecting the return air side of the buffer room 19 with the main engine room 18. In the summer drying mode, the second fresh air valve 10 and the dehumidification valve fan assembly 12 need to be continuously opened to introduce outdoor ambient air into the main engine room 18 through the second fresh air valve 10 and the fresh air duct 11 to increase the temperature of the main engine room 18 and provide a heat source for the heat pump unit 1. In the drying process, the air discharged into the main engine room 18 by the return air chamber 17 is directly discharged into the environment through the dehumidification valve fan assembly 12. The first fresh air valve 8 and a pair of return air valves replenish fresh air to the dryer. The positive and reverse airflow circulation process of the drying chamber 16 and the return air chamber 17 is as described in the winter working condition.

[0059] In this embodiment, 1. the problem of low performance of the heat pump system under low ambient temperature is solved, and the energy efficiency of the heat pump system is improved by using closed-loop and semi-open operation models.

[0060] 2. The fresh air circulation in the main engine room 18 can effectively improve the performance of the heat pump system under the summer conditions in the north.

[0061] 3. The control logic of the main engine room 18 is adopted to connect multiple drying units in parallel, so as to realize the sharing of waste heat source and solve the problems of difficult operation, slow preheating and low efficiency of the heat pump system in the preheating stage under low ambient temperature.

[0062] 4. Each unit is independently controlled. The heat pump system can realize the standardized production of the drying processing plant, and each drying unit can realize the drying processing of different materials.

[0063] 5. A horizontally arranged reversible dryer is used to solve the problem of uneven drying of materials in the drying chamber 16 and improve drying efficiency.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-stage heat pump drying unit parallel system, characterized in that: The invention comprises a plurality of dryers arranged in parallel and a main engine room arranged on one side of the plurality of dryers and shared by the plurality of dryers, each of the dryers being divided into a pair of drying chambers, a return air chamber arranged between the pair of drying chambers, and a buffer chamber separated from the pair of drying chambers and the return air chambers and located on the top of the pair of drying chambers and the return air chambers, a feeding door is arranged on the end side wall of the drying chamber away from the main engine room, a shunt structure communicating with the drying chamber is arranged on the side wall of the return air chamber adjacent to each of the drying chambers, a circulating fan and a condenser for heating circulating air are arranged in the return air chamber, The side walls of the return air chamber adjacent to the buffer chamber are respectively provided with a return air valve and an exhaust air valve, the return air chamber is provided with a first partition separating the return air valve and the exhaust air valve, and the top wall of the buffer chamber is provided with a first fresh air valve; the exhaust air valve is connected to the exhaust air duct of the main engine room through the buffer chamber, and the return air valve is directly connected to the main engine room through the buffer chamber; a heat pump unit corresponding to each dryer is provided in the main engine room, a second fresh air valve is provided on one side wall of the main engine room, a fresh air duct connected to the second fresh air valve is provided in the main engine room, and a dehumidification valve fan assembly is provided on the other side wall of the main engine room; The main engine room is provided with heat storage material, each of the heat pump units comprises an evaporator and the condenser provided in the return air room, and the evaporator is provided in the main engine room; The return air chamber is provided with a temperature and humidity sensor.

2. The multi-stage heat pump drying unit parallel system according to claim 1, characterized in that: The return air chamber is provided with a pair of exhaust valves along its length direction, which are a first exhaust valve and a second exhaust valve. The first exhaust valve and the second exhaust valve are respectively arranged on both sides of the condenser. A guide plate is provided at each exhaust valve in the return air chamber.

3. The multi-stage heat pump drying unit parallel system according to claim 2, characterized in that: The return air chamber is provided with a pair of return air valves along its length direction, which are the first return air valve and the second return air valve. The first return air valve and the second return air valve are respectively arranged on both sides of the condenser; the pair of exhaust valves and the pair of return air valves are separated by the first partition.

4. The multi-stage heat pump drying unit parallel system according to claim 2, characterized in that: The circulating fan is a forward and reverse rotating fan; The dehumidification valve and fan assembly includes an independently controlled dehumidification valve and a fan; The flow splitting structure includes a flow splitting plate and flow splitting blades.

5. The multi-stage heat pump drying unit parallel system according to claim 1, characterized in that: The main engine room and the plurality of dryers are separated by a second partition, the second fresh air valve is arranged near the top of the second partition, and the fresh air duct is fixed on the second partition.

6. The multi-stage heat pump drying unit parallel system according to claim 5, characterized in that: The second partition plate is provided with an inspection port at a position corresponding to each of the dryers.

7. The multi-stage heat pump drying unit parallel system according to claim 1, characterized in that: The heat pump unit is provided with a condensed water outlet, and the condensed water outlet is connected to the underground drainage system.

8. The multi-stage heat pump drying unit parallel system according to claim 1, characterized in that: The main engine room is provided with inspection doors on opposite sides along the length direction thereof.

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