CN212538541U

CN212538541U - Multistage heat pump drying system

Info

Publication number: CN212538541U
Application number: CN202022187365.3U
Authority: CN
Inventors: 苑亚; 杨鲁伟; 董建; 魏娟; 李博; 金建龙
Original assignee: Technical Institute of Physics and Chemistry of CAS
Current assignee: Technical Institute of Physics and Chemistry of CAS
Priority date: 2020-09-29
Filing date: 2020-09-29
Publication date: 2021-02-12
Anticipated expiration: 2030-09-29

Abstract

The utility model relates to a heat pump drying equipment technical field especially relates to a multistage heat pump drying system. This multistage heat pump drying system includes: the main machine room is internally provided with a plurality of heat pump units in parallel; the drying units are connected to the same main machine room in parallel, air outlets and air return inlets are respectively arranged at the connection positions of the drying units and the main machine room, and the air outlets and the air return inlets of each group are respectively arranged around each heat pump unit in a one-to-one correspondence manner; wherein, each group of drying units is provided with a feeding door, internal circulation airflow can be formed among the air return inlet, the feeding door and the air outlet in the drying units, and external circulation airflow can be formed among the drying units, the main machine room and the external environment. In the system, a plurality of drying units share the same main machine room, so that the distribution of the energy consumption of the system can be ensured to be more uniform, and under the condition that the waste heat of any drying unit is insufficient, the waste heat of other drying units can be utilized to quickly make up for the deficiency, and the high-efficiency utilization of the waste heat at the low-ring temperature is realized.

Description

Multistage heat pump drying system

Technical Field

The utility model relates to a heat pump drying equipment technical field especially relates to a multistage heat pump drying system.

Background

Drying is the major energy consuming part of industrial energy consumption, accounting for up to about 15%. In the drying process, the heat pump system can recover waste heat in the drying process, and has the advantages of low energy consumption, high temperature and humidity control precision, high drying efficiency and the like. Therefore, the heat pump drying technology has significant advantages in the drying field.

At present, a part of heat pump drying devices generally adopt a parallel air supply mode to dry materials, but a heat storage device is required to buffer the recycling of waste heat in the drying process. In the other part of the heat pump drying device, different drying working conditions are controlled in a subarea mode on a plurality of heat pump drying units based on subarea control of belt type drying, and the whole drying processing process is realized. In the drying process, the problems of discharge and recycling of waste heat at low ring temperature, uneven energy consumption distribution of the system and the like exist, and the problems cause that the overall energy consumption of the existing heat pump drying system is relatively high. Particularly in the cold environment in winter in the north, the above problems cause the heat pump systems in semi-open and open systems to have low energy efficiency and even fail to operate normally, and cause the heat load of the heat pump to be reduced, failing to meet the design requirements.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that exists among the prior art at least.

Therefore, the utility model provides a multistage heat pump drying system to it is on the low side to solve current heat pump drying device system performance under the low ring temperature, and the emission recycle of used heat is not enough, and the uneven problem of energy consumption distribution of system.

According to the utility model discloses multistage heat pump drying system of first aspect embodiment includes:

the main machine room is internally provided with a plurality of heat pump units in parallel;

the drying units are connected to the same main machine room in parallel, air outlets and air return openings are formed in the connection positions of the drying units and the main machine room respectively, and the air outlets and the air return openings of each group are arranged around the heat pump units in a one-to-one correspondence mode respectively;

the drying unit is characterized in that a feeding door is arranged on each group of drying units, internal circulation airflow can be formed among the air return inlet, the feeding door and the air outlet in each drying unit, and external circulation airflow can be formed among the drying units, the main machine room and the external environment.

According to the utility model discloses an embodiment, be separated for heating chamber, drying chamber and return-air chamber in the drying unit, the heating chamber with the drying chamber is constructed according to the preface in the feeding gate with between the return-air inlet, the return-air chamber is constructed in the feeding gate with between the air exit, the return-air chamber respectively with the heating chamber with the drying chamber intercommunication.

According to an embodiment of the present invention, the drying unit includes a closed box, a partition and a return air plate, one end of the closed box is connected to the main room through the partition, the other end of the closed box is configured with the feeding door, the return air plate is disposed in the closed box, the return air plate is used for dividing the interior of the closed box into a drying space and a return air chamber which are vertically arranged in parallel, and the heating chamber and the drying chamber which are communicated with each other are sequentially configured from the partition to the feeding door in the drying space; one end of the air return plate faces the partition plate, a first air supply opening is reserved between the air return plate and the partition plate, and the other end of the air return plate faces the feeding door, and a second air supply opening is reserved between the air return plate and the feeding door; the air return inlet and the air outlet are both arranged on the partition board in the air return chamber.

According to the utility model discloses an embodiment, be equipped with circulating fan and condenser in the drying unit, circulating fan transversely arranges in the heating chamber with the hookup location of drying chamber, and be connected the return air board dorsad the surface of return air room, the condenser transversely arranges in the heating chamber.

According to the utility model discloses an embodiment, drying unit still includes the exhaust airway, the exhaust airway wears to establish in the air exit, the one end of exhaust airway is located in the return air is indoor, the other end of exhaust airway is located the host computer is indoor and be located one side of heat pump set.

According to the utility model discloses an embodiment, the wind channel includes first passageway and second passageway, first passageway with the junction of second passageway is worn to establish in the air exit, first passageway is located in the return air chamber and the laminating is in the surface of return air plate, the second passageway is located the host computer is indoor and the laminating is in the surface of baffle.

According to the utility model discloses an embodiment, the exhaust airway is located exhaust valve is installed to indoor tip of host computer.

According to the utility model discloses an embodiment, the lateral wall of return-air chamber is equipped with the fresh air inlet that is used for communicateing external environment, the fresh air inlet orientation first supply-air outlet sets up, the fresh-air valve is installed to the fresh air inlet.

According to the utility model discloses an embodiment, the return air valve is installed to the return air inlet.

According to the utility model discloses an embodiment, the lateral wall of host computer room is equipped with the inspection door that can open and close the outer wall of host computer room is equipped with the hydrofuge mouth that is used for communicateing the external environment, the hydrofuge valve is installed to the hydrofuge mouth.

The embodiment of the utility model provides an in above-mentioned one or more technical scheme, one of following technological effect has at least:

the utility model discloses multistage heat pump drying system of embodiment includes: the main machine room is internally provided with a plurality of heat pump units in parallel; the drying units are connected in the same host room in parallel, air outlets and air return inlets are formed in the joints of the drying units and the host room, and the air outlets and the air return inlets of each group are arranged around the heat pump units in a one-to-one correspondence mode. The system can be with a plurality of drying unit parallel connection on same host computer room, so that the same host computer room of a plurality of drying unit sharing, thereby under the condition that there is the used heat of arbitrary drying unit not enough, can utilize the used heat of other drying units to compensate, realize the used heat source sharization of a plurality of drying units, guarantee that each drying unit all has used heat utilizability in the system preheating stage promptly, and can both make full use of used heat at all drying unit in the in-process that carries out drying process, can improve the multistage heat pump drying system under the low temperature environment (promptly "low ring temperature") at the operating performance in preheating stage, improve preheating efficiency and reduce preheating stage required time, can guarantee again that the distribution of system's energy consumption is more even, the high-efficient utilization of used heat in the realization system.

Further, multistage heat pump drying system in, be equipped with the feed gate on the drying unit, can form the inner loop air current between inherent return air inlet of drying unit, feed gate and the air exit, can form the extrinsic cycle air current between drying unit, host computer room and the external environment. The multistage heat pump drying system can realize a closed drying operation mode, a semi-open drying operation mode or a coupling drying operation mode, the dehumidification amount of the heat pump unit is adjusted by utilizing the inner circulation airflow in the closed drying operation mode, the dehumidification amount of the heat pump unit is adjusted by utilizing the outer circulation airflow in the semi-open drying operation mode, and the dehumidification amount of the heat pump unit is synchronously adjusted by utilizing the inner circulation airflow and the outer circulation airflow in the coupling drying operation mode, so that the operation performance of the multistage heat pump drying system is greatly improved, particularly, the operation performance of the system in a low-environment-temperature state is improved, the adverse influence of the external environment on the heat pump performance is avoided, and energy conservation and emission reduction are realized.

Furthermore, in the multi-stage heat pump drying system according to the embodiment of the present invention, since the plurality of drying units are arranged in parallel and are independent from each other, the drying units do not interfere with each other; also, each drying unit may achieve independent drying requirements, e.g., control of temperature, humidity, and airflow rate within the drying unit are independent of each other. Therefore, the multistage heat pump drying system can dry different materials in different drying units, so that the system operation efficiency is further improved, and the production cost is reduced.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic top view of a multistage heat pump drying system according to an embodiment of the present invention;

fig. 2 is a schematic view of the structure in the direction a-a shown in fig. 1.

Reference numerals:

1: a heat pump unit; 2: a condenser; 3: a circulating fan; 4: a return air plate; 5: an exhaust duct; 51: a first channel; 52: a second channel; 6: an exhaust valve; 7: a return air valve; 8: a fresh air valve; 9: a moisture removal valve; 10: a feed gate; 11: an inspection door; 12: a heating chamber; 13: a drying chamber; 14: a main machine room; 15: an air return chamber.

Detailed Description

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings and examples. The following examples are intended to illustrate the invention, but are not intended to limit the scope of the invention.

As shown in fig. 1 and fig. 2, an embodiment of the present invention provides a multistage heat pump drying system (in an embodiment of the present invention, referred to as a "drying system" for short). And based on this drying system, the embodiment of the utility model provides a multistage heat pump drying method (the embodiment of the utility model provides an in short "drying method") still is provided.

As shown in fig. 1 and 2, the drying system includes a main cabinet 14 and a plurality of sets of drying units. Several groups of drying units share the same main cabinet 14. Wherein, a plurality of heat pump units 1 are arranged in parallel in the main room 14. The heat pump unit 1 is preferably a heat pump apparatus not including the condenser 2 for recovering latent heat and sensible heat in the exhaust gas. The plurality of groups of drying units are connected to the same main machine room 14 in parallel, air outlets and air return inlets are respectively arranged at the joints of each group of drying units and the main machine room 14, and the air outlets and the air return inlets of each group are respectively arranged around each heat pump unit 1 in a one-to-one correspondence manner. Because each drying unit shares the main machine room 14, waste heat airflow generated by any heat pump unit 1 can enter any drying unit through any air return opening, but preferentially enters the drying unit corresponding to the heat pump unit 1; the air outlet can send the airflow in the drying unit into the corresponding heat pump unit 1.

It can be seen that, embodiment drying system can be with a plurality of drying unit parallel connection on same host computer room 14, so that same host computer room 14 of a plurality of drying unit sharing, thereby under the condition that there is the used heat of arbitrary drying unit not enough, can utilize the used heat of other drying units to compensate, realize the used heat source sharization of a plurality of drying units, guarantee that each drying unit all has used heat utilizability in the system preheating stage promptly, and can both make full use of used heat at all drying unit in the in-process of carrying out drying process, can improve the operating performance of multistage heat pump drying system under the low temperature environment (promptly "low ring temperature") at the preheating stage, improve preheating efficiency and reduce preheating stage required time, can guarantee again that the distribution of system energy consumption is more even, realize the high-efficient utilization of used heat in the system.

In the drying system provided by the embodiment of the utility model, because a plurality of groups of drying units are arranged in parallel and are mutually independent, the drying units can not interfere with each other; also, each drying unit may achieve independent drying requirements, e.g., control of temperature, humidity, and airflow rate within the drying unit are independent of each other. Therefore, the multistage heat pump drying system can dry different materials in different drying units, so that the system operation efficiency is further improved, and the production cost is reduced.

The embodiment of the utility model provides a drying system in, be equipped with feed gate 10 on every group drying unit respectively, the material carries out drying process in getting into drying unit through feed gate 10. An internal circulating airflow can be formed among the air return inlet, the feeding door 10 and the air outlet in each group of drying units; the drying units, the main machine room 14 and the external environment can form external circulation air flow respectively. The drying system can execute a closed drying operation mode, a semi-open drying operation mode or a coupling drying operation mode, the humidity of the main machine chamber 14 is adjusted by utilizing the inner circulation air flow in the closed drying operation mode, the humidity of the main machine chamber 14 is adjusted by utilizing the outer circulation air flow in the semi-open drying operation mode, and the humidity of the main machine chamber 14 is synchronously adjusted by utilizing the inner circulation air flow and the outer circulation air flow in the coupling drying operation mode, so that the operation performance of the multistage heat pump drying system is greatly improved, particularly, the system operation performance in a low-ring-temperature state is improved, the adverse effect of the external environment on the heat pump performance is avoided, and energy conservation and emission reduction are realized.

Understandably, the embodiment of the utility model provides an air current flow direction of inner loop air current do: the airflow in the air return chamber 15 of the drying unit enters the main machine chamber 14 through an air outlet, and is cooled and dehumidified by the heat pump unit 1; the cooled and dehumidified air flows back into the drying unit through the air return opening, and finally is exhausted into the main machine room 14 through the air outlet after sequentially passing through the heating room 12, the drying room 13 and the air return room 15.

Understandably, the embodiment of the utility model provides an outer circulation air current's air current flow direction do: on one hand, the airflow of the external environment enters the drying unit, and is discharged into the main machine chamber 14 through an exhaust outlet after sequentially passing through the heating chamber 12, the drying chamber 13 and the air return chamber 15 according to the flow direction of the internal circulation airflow in the drying unit; on the other hand, the airflow in the air return chamber 15 of the drying unit enters the main machine chamber 14 through the air outlet, meanwhile, the airflow in the external environment enters the main machine chamber 14, and is cooled and dehumidified by the heat pump unit 1 together with the airflow discharged from the air outlet, and the cooled and dehumidified air is discharged from the main machine chamber 14 to the external environment.

It can be understood that in order to conveniently regulate and control the opening and closing, the flow speed and the flow of the air flow, the return air inlet is preferably provided with a return air valve 7. In order to facilitate the rapid discharge of the airflow from the main machine room 14, it is preferable that a moisture discharge port for communicating with the external environment be provided on the outer wall of the main machine room 14, and the moisture discharge port be provided with a moisture discharge valve 9. The moisture exhaust valve 9 can exhaust the air in the main cabinet 14 to the external environment, and can adjust the flow rate and flow rate of the gas. Preferably, the side wall of the main machine room 14 is provided with an openable inspection door 11, the inspection door 11 can ensure that the main machine room 14 is communicated with the external environment, a semi-open space can be formed in the main machine room 14 by opening the inspection door 11, and the inspection door 11 can also facilitate the maintenance of the heat pump unit 1.

In one embodiment, the interior of the drying unit is divided into a heating chamber 12, a drying chamber 13 and a return air chamber 15. The heating chamber 12 and the drying chamber 13 are sequentially configured between the feeding door 10 and the air return opening, the air return chamber 15 is configured between the feeding door 10 and the air outlet, and the air return chamber 15 is respectively communicated with the heating chamber 12 and the drying chamber 13. The material enters the drying chamber 13 from the feeding door 10 to be dried. As shown in fig. 2, the internal circulation airflow is formed inside the drying unit, specifically: the air flow in the main machine room 14 sequentially enters the heating room 12, the drying room 13 and the air return room 15 through the air return opening, and finally is exhausted into the main machine room 14 again through the air exhaust opening.

In one embodiment, as shown in fig. 2, the drying unit includes an enclosed box, a partition and a return air plate 4. One end of the closed box is connected with the main machine room 14 through a partition plate, and the other end of the closed box is provided with a feeding door 10. The air return plate 4 is arranged in the closed box body, and the air return plate 4 is used for dividing the closed box body into a drying space and an air return chamber 15 which are vertically arranged in parallel, namely as shown in figure 2, the air return chamber 15 is positioned above the drying space. A heating chamber 12 and a drying chamber 13 communicating with each other are formed in the drying space in sequence from the partition wall toward the feed gate 10. One end of the air return plate 4 faces the partition plate and a first air supply opening is reserved between the air return plate and the partition plate, the other end of the air return plate 4 faces the feeding door 10 and a second air supply opening is reserved between the air return plate and the feeding door 10, and the air return opening and the air outlet are both arranged on the partition plate located in the air return chamber 15. The internal circulation air flow enters the drying unit from the air return opening, and directly enters the heating chamber 12 from the air return chamber 15 through the first air supply opening under the condition of not penetrating the air return chamber 15, the air flow flowing through the drying chamber 13 enters the air return chamber 15 through the second air supply opening, and is discharged into the main machine chamber 14 through the air outlet on the partition plate after penetrating the air return chamber 15. The structure makes the internal structure of the drying unit compact, is more beneficial to structural optimization, simplifies the path of the drying air flow and relatively prolongs the time for the air flow to flow through the drying chamber 13 and the air return chamber 15. On one hand, the retention time of the airflow in the drying chamber 13 is increased, so that waste heat carried in the airflow can be more fully utilized in the drying treatment of the materials, the drying treatment efficiency and the drying effect are improved, and the system operation performance is further improved; on the other hand, the retention time of the air flow in the air return chamber 15 is increased, so that more air flow can be stored in the air return chamber 15, and the drying system is convenient to adjust the humidity in the main chamber 14 more accurately and efficiently in the closed drying operation mode and the coupling drying operation mode.

In one embodiment, a circulation fan 3 and a condenser 2 are provided in the drying unit. The circulating fan 3 is horizontally arranged at the connecting position of the heating chamber 12 and the drying chamber 13 and is connected to the surface of the return air board 4 opposite to the return air chamber 15. The circulating fan 3 is used for providing power for the internal circulating airflow. The condenser 2 is disposed across the heating chamber 12, and the condenser 2 is used for heating the internal circulation airflow passing therethrough so that the internal circulation airflow can perform a drying process in the drying chamber 13.

In one embodiment, the drying unit further comprises an exhaust duct 5. The exhaust duct 5 is arranged in the exhaust outlet in a penetrating way. One end of the exhaust duct 5 is located in the air return chamber 15. The air flow sucked from the air return chamber 15 by the air return duct is used as return air flow, the air flow entering the air return chamber 15 through the air return opening and passing through the first air supply opening is used as exhaust air flow, and the end part of the exhaust duct 5 positioned in the air return chamber 15 preferably extends towards the direction of the feeding door 10 and exceeds the position of the first air supply opening, so that the return air flow and the exhaust air flow are not interfered with each other. The other end of the exhaust duct 5 is located in the main room 14 and on one side of the heat pump unit 1, so as to ensure that the airflow discharged from the exhaust duct 5 can act on the heat pump unit 1 corresponding to the current drying unit more directly.

Preferably, as shown in fig. 2, the exhaust duct 5 includes a first passage 51 and a second passage 52. The connection part of the first channel 51 and the second channel 52 is arranged in the air outlet in a penetrating way. A first channel 51 is located in the return air compartment 15 and abuts the surface of the return air panel 4 and a second channel 52 is located in the main compartment 14 and abuts the surface of the partition. The first passage 51 serves to separate the return air flow from the exhaust air flow in the return air chamber 15. The second channel 52 is used to optimize the design of the pipeline structure in the main room 14, and guide the exhaust air flow to the periphery of the corresponding heat pump unit 1, so that the exhaust air flow of each group of drying units can more accurately act on the corresponding heat pump unit 1, and the system operation efficiency is improved.

Understandably, in order to conveniently regulate and control the opening and closing, the flow speed and the flow of the air flow, the end part of the exhaust duct 5 positioned in the main machine room 14 is provided with an exhaust valve 6.

It will be appreciated that the side walls of the return air chamber 15 are preferably provided with fresh air ports for communication with the outside environment. The fresh air inlet is arranged towards the first air supply outlet, so that fresh air energy is more preferentially converged into the internal circulation airflow, and the operation process of the coupling drying operation mode is smoother. Preferably, the fresh air inlet is provided with a fresh air valve 8, and the fresh air valve 8 is used for introducing air flow into the air return chamber 15 from the external environment and can reliably regulate and control the opening and closing, the flow speed and the flow of the air flow.

The embodiment of the utility model provides a drying method is carried out by foretell multistage heat pump drying system. The drying method can execute a closed drying operation mode, a semi-open drying operation mode and a coupling drying operation mode. The drying method can reliably adjust the dehumidification amount of the heat pump unit 1 in different modes, and reliably adjust the temperature and the humidity in the drying chamber 13 and the main machine chamber 14, so that the system has better operation performance in low-ring temperature, the universality of system operation is improved, and the service life of the system is prolonged.

In the closed drying operation mode, the temperature in the corresponding drying unit is adjusted by adjusting the working parameters of each heat pump unit 1 in the main machine room 14; and when the humidity in the main machine room 14 is lower than a set humidity standard value, forming an internal circulation airflow in the drying unit, and adjusting the dehumidification amount of the heat pump unit 1 by using the internal circulation airflow.

Specifically, the method comprises the following steps: during the drying process, the inspection doors 11 at both sides of the main cabinet 14 are closed, and the fresh air valve 8 and the dehumidifying valve 9 are in a closed state. When the temperature of the drying chamber 13 is lower than a temperature set value, the temperature in the drying chamber 13 is increased by increasing the frequency of a compressor in the heat pump unit 1 or starting the compressor; when the temperature of the drying chamber 13 meets the temperature set value, the current starting situation of the heat pump unit 1 is maintained; when the temperature of the drying chamber 13 is higher than the temperature set value, the frequency of the compressor in the heat pump unit 1 is reduced or the compressor is turned off. When the humidity in the main room 14 is lower than the humidity set value, the exhaust valve 6 and the return valve 7 are opened, the air in the return chamber 15 is exhausted into the main room 14, the air is cooled and dehumidified by the heat pump unit 1, and then exhausted into the heating room 12 through the return valve 7, and the dehumidification capacity of the heat pump unit 1 and the temperature of the main room 14 are controlled by adjusting the opening degrees of the exhaust valve 6 and the return valve 7.

In the semi-open type drying operation mode, the temperature in the corresponding drying unit is adjusted by adjusting the working parameters of each heat pump unit 1; and when the humidity in the drying unit is higher than a set humidity standard value, an external circulation airflow is formed among the drying unit, the main machine room 14 and the external environment, and the dehumidification amount of the heat pump unit 1 is adjusted by using the external circulation airflow.

Specifically, the method comprises the following steps: during the drying process, the inspection doors 11 on both sides of the main cabinet 14 are in an open state, and the return damper 7 is in a closed state. In the semi-open type drying operation mode, the temperature control process of the drying chamber 13 is basically consistent with that of the closed type drying operation mode, and the specific control process is detailed in the closed type drying operation mode part and is not described again; when the humidity of the drying chamber 13 is higher than the humidity set value, the fresh air valve 8, the exhaust valve 6 and the dehumidifying valve 9 are opened, the air in the air return chamber 15 is exhausted into the main machine chamber 14 through the exhaust duct 5 and the exhaust valve 6, the air exhausted into the main machine chamber 14 is cooled and dehumidified by the heat pump unit 1, and then the air is exhausted into the environment through the dehumidifying valve 9.

In the coupling drying operation mode, the temperature in the corresponding drying unit is adjusted by adjusting the working parameters of each heat pump unit 1; and synchronously adjusting the dehumidification amount of the heat pump unit 1 by utilizing the internal circulation airflow and the external circulation airflow.

Specifically, the method comprises the following steps: and carrying out coupling operation on the semi-open type drying mode and the closed type drying mode. In the coupling drying operation mode, the temperature control process of the drying chamber 13 is basically consistent with the semi-open drying mode and the closed drying mode, and the detailed control process is referred to as the closed drying operation mode part and is not described herein again; in the aspect of humidity control, firstly, the temperature of the main machine room 14 and the humidity of the drying room 13 are controlled by adjusting the opening degrees of the exhaust valve 6 and the return air valve 7, and when the humidity requirement of the drying room 13 cannot be met by adjusting and controlling the exhaust valve 6 and the return air valve 7, the new air valve 8, the exhaust valve 6 and the dehumidifying valve 9 are adjusted and controlled.

Therefore, the embodiment of the utility model provides an among the drying method, the dry operation mode of coupling can be more effectual reduces the influence of external factors (for example low temperature environment) to heat pump set 1 performance to semi-open drying mode and closed drying mode's control advantage has been combined.

It can be understood that the drying method is performed by the multi-stage heat pump drying system as described above, so that the multi-stage heat pump drying method also has all the advantages of the multi-stage heat pump drying system, and will not be described herein again.

In the description of the embodiments of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing the embodiments of the present invention and simplifying the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the embodiments of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected" and "connected" should be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meaning of the above terms in the embodiments of the present invention can be understood in specific cases by those skilled in the art.

In embodiments of the invention, unless expressly stated or limited otherwise, the first feature may be directly on or directly under the second feature or indirectly via intermediate members. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of an embodiment of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

The above embodiments are merely illustrative, and not restrictive, of the present invention. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that various combinations, modifications or equivalent substitutions may be made to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention, and all of the technical solutions should be covered by the scope of the claims of the present invention.

Claims

1. A multi-stage heat pump drying system, comprising:

2. The multi-stage heat pump drying system of claim 1, wherein the drying unit is partitioned into a heating chamber, a drying chamber and an air return chamber, the heating chamber and the drying chamber are sequentially configured between the feed gate and the air return opening, the air return chamber is configured between the feed gate and the air outlet, and the air return chamber is respectively communicated with the heating chamber and the drying chamber.

3. The multistage heat pump drying system according to claim 2, wherein the drying unit comprises a closed box, a partition plate and a return air plate, one end of the closed box is connected with the main machine room through the partition plate, the other end of the closed box is provided with the feed door, the return air plate is arranged in the closed box, the return air plate is used for dividing the closed box into a drying space and the return air chamber which are vertically arranged in parallel, and the heating chamber and the drying chamber which are communicated with each other are sequentially arranged in the drying space from the partition plate to the feed door; one end of the air return plate faces the partition plate, a first air supply opening is reserved between the air return plate and the partition plate, and the other end of the air return plate faces the feeding door, and a second air supply opening is reserved between the air return plate and the feeding door; the air return inlet and the air outlet are both arranged on the partition board in the air return chamber.

4. The multi-stage heat pump drying system of claim 3, wherein a circulating fan and a condenser are disposed in the drying unit, the circulating fan is disposed across a connection between the heating chamber and the drying chamber and is connected to a surface of the return air plate facing away from the return air chamber, and the condenser is disposed across the heating chamber.

5. The multi-stage heat pump drying system of claim 3, wherein the drying unit further comprises an exhaust duct, the exhaust duct is arranged in the exhaust outlet in a penetrating manner, one end of the exhaust duct is located in the return air chamber, and the other end of the exhaust duct is located in the main unit chamber and located on one side of the heat pump unit.

6. The multi-stage heat pump drying system of claim 5, wherein the air duct comprises a first channel and a second channel, a connection portion of the first channel and the second channel penetrates through the air outlet, the first channel is located in the return air chamber and attached to the surface of the return air plate, and the second channel is located in the main machine chamber and attached to the surface of the partition plate.

7. The multi-stage heat pump drying system of claim 5, wherein an exhaust valve is installed at an end of the exhaust duct located in the main unit chamber.

8. The multi-stage heat pump drying system of claim 3, wherein a fresh air port for communicating with the external environment is provided on a side wall of the air return chamber, the fresh air port is disposed toward the first air supply port, and a fresh air valve is installed on the fresh air port.

9. The multi-stage heat pump drying system of any one of claims 1 to 8, wherein the return air inlet is fitted with a return air valve.

10. The multistage heat pump drying system according to any one of claims 1 to 8, wherein a side wall of the main machine chamber is provided with an openable and closable inspection door, and a moisture discharge port for communicating with an external environment is provided in an outer wall of the main machine chamber, and the moisture discharge port is provided with a moisture discharge valve.