Heat pump drying system and control device and control method thereof

Abstract

The invention discloses a heat pump drying system and a control device and method thereof, and relates to the technical field of heat pump drying, and the heat pump drying system comprises a heat pump part which comprises at least one heat pump unit and is used for providing drying hot air; the drying part is used for carrying out drying operation by utilizing the drying hot air and outputting moisture-containing tail gas; the dehumidification heat exchange part comprises at least one fin evaporator, the number of the fin evaporators is the same as that of the heat pump units, the fin surfaces of the fin evaporators are provided with adsorbents, the adsorbents are used for carrying out adsorption dehumidification on the moisture-containing tail gas and generating heat and dry return air, and when the system runs, the heat is absorbed by the heat pump units, and the dry return air is used for drying the moisture-containing tail gas. The dry return air is heated by the heat pump unit to form dry hot air; and the adsorption regeneration part is used for desorbing the adsorbent by using the dry hot air. The power consumption of the heat pump system can be reduced, and the energy efficiency of the heat pump system is improved. Meanwhile, the capacity of the heat pump system can be reduced, and the effect of reducing system investment is achieved.

Description

Technical Field

[0001] The present application relates to the technical field of heat pump drying, and in particular to a heat pump drying system and a control device and a control method thereof. Background Art

[0002] As a new drying method, heat pump drying has the advantages of high efficiency and energy saving, low cost, no pollution to the environment, and accurate and independent automatic control of the temperature and humidity of the drying medium. Therefore, it has good drying quality and has been widely used in wood drying, seed drying, food processing, sludge drying and other fields. However, as a thermal conversion device that converts low-grade thermal energy into high-grade thermal energy, the application of heat pump is greatly affected by the heat source and heating temperature. Therefore, how to save energy while ensuring the working efficiency of the drying system is the focus and difficulty of the research.

[0003] At present, there is technology that uses air source heat pumps in drying systems. However, air source heat pumps are restricted by time and space in extracting heat from the environment. For example, in winter and cold northern regions, air source heat pumps are difficult to operate or have high energy consumption and low efficiency. There are also drying systems that combine solar energy with heat pumps. In areas and times with sufficient sunshine, they can effectively reduce energy consumption and shorten drying time. However, solar energy cannot be used as a reliable heat source to ensure the long-term and efficient operation of heat pump drying systems. There are also time and space application limitations. There are also heat pump systems that recover the waste heat of exhaust gas from closed drying systems. While absorbing the waste heat of exhaust gas through the evaporator, the system cools and condenses the dry exhaust gas with high moisture content and supplies hot air at the same time. However, the heat pump of this system needs to provide a higher heating capacity. Summary of the invention

[0004] In order to solve the above technical problems, the present application designs a heat pump drying system and its control device and control method, which reduces the temperature rise of the heat pump system, thereby reducing the power consumption of the heat pump system and improving the energy efficiency of the heat pump system. At the same time, the return air temperature of the heat pump system is relatively high, so that the heat pump system heats the return air to the required temperature with a smaller heating capacity, thereby reducing the capacity of the heat pump system and achieving the effect of reducing system investment.

[0005] To achieve the above objectives, this application provides the following technical solutions:

[0006] A first aspect of the present application provides a heat pump drying system, comprising:

[0007] The heat pump unit includes at least one heat pump unit, and the heat pump unit is used to provide dry hot air;

[0008] A drying section, used for performing a drying operation using the dry hot air and outputting a wet tail gas;

[0009] The dehumidification heat exchange part includes at least one fin evaporator, and the number of the fin evaporators is the same as the number of the heat pump units, wherein:

[0010] The fin surface of each fin evaporator has an adsorbent, and the adsorbent is used to adsorb and dehumidify the humid exhaust gas and generate heat and dry return air. When the system is running, the heat is absorbed by the heat pump unit, and the dry return air is heated by the heat pump unit to form the dry hot air;

[0011] The adsorption regeneration section is used to utilize the dry hot air to perform a desorption operation on the adsorbent.

[0012] A second aspect of the present application provides a control device, which is used to control the heat pump drying system as described in the first aspect, and the control device includes:

[0013] A first detection module is used to detect the weight of each fin evaporator;

[0014] A second detection module, used for detecting a first temperature of the wet exhaust gas input to each of the fin evaporators;

[0015] A third detection module is used to detect the second temperature of the dry hot air output by each heat pump unit;

[0016] A main control module is respectively connected to the first detection module, the second detection module, the third detection module, the heat pump unit, the drying part, the dehumidification heat exchange part and the adsorption regeneration part;

[0017] Wherein, when the desorption operation of the adsorbent of one of the fin evaporators is to be performed, the main control module is used to obtain the weight of the corresponding fin evaporator measured by the first detection module, and obtain the moisture content of the adsorbent based on the weight, and compare the moisture content with the desorption completion standard value;

[0018] When the moisture content does not reach the desorption completion standard value, the main control module is further used to obtain the first temperature measured by the second detection module, and set the evaporation temperature, condensation temperature and compressor frequency of the corresponding heat pump unit based on the first temperature and the regeneration temperature of the adsorbent, and control the adsorption regeneration unit to perform desorption operation on the adsorbent of the corresponding fin evaporator;

[0019] When the desorption operation of the adsorbent of one of the fin evaporators is completed, the main control module is also used to control the adsorption regeneration part to stop working, and obtain the second temperature measured by the third detection module, and set the condensing temperature of the corresponding heat pump unit based on the target drying temperature, and adjust the compressor frequency of the corresponding heat pump unit based on the second temperature and the target drying temperature, until the temperature difference between the second temperature and the target drying temperature reaches the target value, and then control the drying part and the dehumidification heat exchange part to start working.

[0020] A third aspect of the present application provides a control method, which is used to control the heat pump drying system according to the first aspect, and the control method includes:

[0021] Controlling the heat pump unit of the heat pump section to heat the dry return air to provide dry hot air;

[0022] Controlling the drying section to perform drying operation using the dry hot air and outputting the wet tail gas;

[0023] Controlling the finned evaporator of the dehumidification heat exchange part to perform adsorption dehumidification on the humid tail gas and generate heat and the dry return air, wherein the heat is absorbed by the heat pump unit;

[0024] The adsorption regeneration unit is controlled to perform a desorption operation on the adsorbent on the fin surface of the fin evaporator by using the dry hot air.

[0025] Compared with the prior art, the technical solution of the present application has the following beneficial effects:

[0026] The present application achieves adsorption dehumidification of dry exhaust gas by arranging an adsorbent on the fin surface of the fin evaporator, and in the process of adsorption dehumidification, the adsorption condensation heat generated is recycled by the heat pump system. By improving the quality of the heat pump system, high-temperature dry hot air supply is achieved. The heat pump system is used to replace the original fuel boiler or the electric boiler with higher power consumption, so as to achieve low-energy drying.

[0027] Adsorption dehumidification with adsorbent can reduce the condensation load demand (i.e. increase the moisture condensation temperature and the heat pump evaporation temperature) while achieving more efficient dehumidification. Therefore, the heat pump system is more energy-efficient. At the same time, the return air temperature after dehumidification of the wet exhaust gas is higher, and the heating capacity of the condenser of the heat pump system required to heat the return air to the required temperature is smaller, which can reduce the capacity of the heat pump system and achieve the effect of reducing system investment.

[0028] The operating control logic designed for the heat pump drying system in this application detects the moisture content of the adsorbent and performs start and stop control of the heat pump system, thereby ensuring that more than two heat pumps operate alternately, providing continuous dry hot air and completing desorption and regeneration of the adsorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following drawings describe in detail the exemplary embodiments disclosed in this application. The same reference numerals represent similar structures in several views of the drawings. Those skilled in the art will understand that these embodiments are non-limiting, exemplary embodiments, and the drawings are only used for the purpose of illustration and description, and are not intended to limit the scope of this application. Other embodiments may also accomplish the inventive intent in this application. It should be understood that the drawings are not drawn to scale. Among them:

[0030] Figure 1 This is a schematic structural diagram of a heat pump drying system according to Example 1 of the present application;

[0031] Figure 2 The adsorption isotherms of the three silica gels in Example 2 of the present application at different relative humidities;

[0032] Figure 3 These are the adsorption and analysis performance curves of the three silica gels in Example 2 of the present application at different heating rates;

[0033] Figure 4 This is a schematic diagram of the structure of the control device of Example 3 of the present application;

[0034] Figure 5 This is a flow chart of the control method of Example 4 of the present application;

[0035] Figure 6 A schematic flow chart of a method for alternating operation of a heat pump unit and a fin evaporator in Example 4 of the present application;

[0036] Figure 7 A control logic diagram of a heat pump drying system according to Embodiment 4 of the present application;

[0037] Figure 8 It is the energy efficiency comparison curve of the system of the present invention and the existing system;

[0038] Fig. 9 It is a comparison curve of the heating capacity of the system of the present invention and the existing system. DETAILED DESCRIPTION

[0039] The following description provides specific application scenarios and requirements of the present application, with the purpose of enabling those skilled in the art to make and use the content in the present application. It will be apparent to those skilled in the art that various local modifications to the disclosed embodiments are apparent, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present application. Therefore, the present application is not limited to the embodiments shown, but to the widest scope consistent with the claims.

[0040] In the related art, air source heat pump is used for drying, but this method is subject to the influence of time and space. For example, it cannot be operated in winter in some areas. Even if it can be operated, in order to achieve a drying temperature of 70℃~80℃, the heat pump unit will face a temperature rise of more than 70℃ (the temperature difference between the evaporation temperature and the condensation temperature). At this time, the heat supply of the heat pump is difficult to guarantee, and the system energy efficiency is low. The heat pump system using solar energy as a heat source has high efficiency in times and areas with sufficient sunshine, but it is affected by the periodicity of solar energy and the heating supply is unstable. The heat pump system of the exhaust waste heat of the closed drying system can directly recover the high temperature dry exhaust waste heat. The system temperature rise of the heat pump unit is relatively small compared to the air source heat pump. However, in order to achieve the dew point temperature of the wet exhaust gas, the heat pump system still needs to provide a lower evaporation temperature, and the exhaust temperature is reduced after condensation and dehumidification. When the return air is heated by the heat pump system condenser to continue heating, the heat pump system needs to provide a higher heating capacity.

[0041] Based on this, the embodiment of the present application provides a heat pump drying system and its control device and control method. Compared with the method of directly using a heat pump to recover the waste heat of condensation and reaching the dew point temperature through evaporation, the present application uses an adsorbent to dehumidify the wet exhaust gas, and the required evaporation temperature is higher, thereby making the temperature rise of the heat pump system smaller, thereby making the power consumption of the heat pump system smaller. Therefore, compared with the previous waste heat recovery heat pump system, the heat pump system of the present application has higher energy efficiency. At the same time, since the temperature of adsorption dehumidification is higher than the temperature of condensation dehumidification, the heat pump system of the present application has a higher return air temperature, and the heat pump system heats the return air to the required temperature. The heating capacity is smaller, so the system investment can be reduced by reducing the capacity of the heat pump system.

[0042] In the existing heat pump direct dehumidification condensation heat recovery system, the fin evaporator is in direct contact with the wet exhaust gas. For some drying processes that may contain corrosive components, such as sludge drying, the acidic components will directly adhere to the surface of the evaporator and cause corrosion of the evaporator tubes. The fin surface of the fin evaporator of the present application has an adsorbent, which can avoid direct contact between the corrosive components and the evaporator tubes. At the same time, the adsorbent layer on the surface of the fin evaporator can be replaced regularly, which is beneficial to extend the service life of the fin evaporator.

[0043] The existing control methods applied to heat pump drying are only based on meeting the drying requirements and do not involve the control of more than two heat pumps and the adsorption and desorption processes combined with the adsorbent. The control device and control method described in this application provide corresponding control methods and logic, which can ensure continuous and reliable supply of heat pump hot air.

[0044] Example 1

[0045] Embodiment 1 of the present application provides a heat pump drying system, which includes a heat pump unit, a drying unit, a dehumidification heat exchange unit, and an adsorption regeneration unit. The heat pump unit is used to provide dry hot air, and the drying unit is used to use the dry hot air to perform a drying operation and output the wet tail gas. The dehumidification heat exchange unit can adsorb and dehumidify the wet tail gas and generate heat and dry return air. The adsorption regeneration unit is used to use the dry hot air to desorb the adsorbent in the dehumidification heat exchange unit.

[0046] refer to Figure 1 The heat pump unit includes at least one heat pump unit. This embodiment shows two heat pump units, namely heat pump unit I and heat pump unit II, and each heat pump unit can be used as a backup for each other. The heat pump unit I includes a first evaporator 1, a first compressor 2, a first condenser 3 and a first throttle valve 4 that are circulated and connected. The structure of the heat pump unit II is the same as that of the heat pump unit I, including a second evaporator 1', a second compressor 2', a second condenser 3' and a second throttle valve 4' that are circulated and connected. The first evaporator 1 and the second evaporator 1' can be fin evaporators.

[0047] When the system is running, taking the heat pump unit 1 as an example, the heat generated by adsorption dehumidification is absorbed by the first evaporator 1, and the refrigerant in the first evaporator 1 evaporates from liquid to form refrigerant vapor, enters the first compressor 2 to be compressed, and then enters the first condenser 3 to condense and release heat to form refrigerant liquid, wherein the heat generated by condensation and heat release can heat the dry return air generated by the dehumidification heat exchange unit to form dry hot air, which can be used for drying operation. The refrigerant liquid enters the first throttle valve 4 to reduce temperature and pressure, and then returns to the first evaporator 1.

[0048] The drying part is used to perform drying operation using the drying hot air and output the wet tail gas. In this embodiment, the drying part includes a dried space 9, a drying hot air channel and a wet tail gas channel 13. The drying space 9 is used to accommodate the dried material, for example, the dried material can be wood, seeds, food, sludge, etc. The drying space 9 is provided with an inlet and an outlet for the dried material.

[0049] One end of the dry hot air channel is connected to each of the heat pump units, and the other end is connected to the dried space 9 and the adsorption regeneration unit. A plurality of dry hot air branch channels can be provided at one end of the dry hot air channel connected to each of the heat pump units, and the number of the dry hot air branch channels is connected to the number of the heat pump units and uniquely corresponds. This embodiment shows two dry hot air branch channels, namely a first dry hot air branch channel 10 and a second dry hot air branch channel 10', wherein the first dry hot air branch channel 10 is connected to the heat pump unit I, and the second dry hot air branch channel 10 is connected to the heat pump unit II.

[0050] In some embodiments, a dry hot air output control valve 11 is further provided on the dry hot air channel, and the dry hot air output control valve 11 allows the dry hot air outputted by the corresponding heat pump unit to pass through. As an example, the dry hot air output control valve 11 may be a three-way valve. As an example, the first dry hot air branch channel 10 is opened by the dry hot air output control valve 11, and the second dry hot air branch channel 10' is closed, at which time the dry hot air is provided by the heat pump unit I, or the first dry hot air branch channel 10 is closed by the dry hot air output control valve 11, and the second dry hot air branch channel 10' is opened, at which time the dry hot air is provided by the heat pump unit II.

[0051] One end of the wet exhaust gas channel 13 is connected to the dried space 9, and the other end is connected to the dehumidification heat exchange part.

[0052] When the system is running, taking the heat pump unit I as an example, the dry hot air provided by the heat pump unit I enters the dried space 9 through the first dry hot air branch channel 10. After the dry hot air dries the dried material, a humid exhaust gas is formed. The humid exhaust gas enters the dehumidification heat exchange part through the humid exhaust gas channel 13.

[0053] The dehumidification heat exchange part includes at least one fin evaporator, and the number of the fin evaporators is the same as the number of the heat pump units. The fin surface of each fin evaporator has an adsorbent, which is used to adsorb and dehumidify the humid exhaust gas and generate heat and dry return air. This embodiment shows two fin evaporators, namely a first fin evaporator 18 and a second fin evaporator 18', respectively. The fin surface of the first fin evaporator 18 has a first adsorbent 5, and the fin surface of the second fin evaporator 18' has a second adsorbent 5'.

[0054] When the system is running, taking the first fin evaporator 18 as an example, when the wet exhaust gas output by the wet exhaust gas channel 13 enters the first fin evaporator 18, the first adsorbent 5 on its fins adsorbs and dehumidifies the wet exhaust gas, and the adsorption and dehumidification process generates heat and dry return air, wherein the heat can be absorbed by the first evaporator 1 of the heat pump unit I, and the dry return air can be transported to the first condenser 3 of the heat pump unit I, and the first condenser 3 can heat the dry return air to form the dry hot air required for the drying operation.

[0055] In some embodiments, the dehumidification heat exchange unit further includes a dehumidification air duct, which is connected to the drying unit and each of the fin evaporators, and is used to transport the humid exhaust gas to each of the fin evaporators. As an example, the dehumidification air duct may include a first dehumidification air duct 6 and a second dehumidification air duct 6', wherein the first dehumidification air duct 6 is connected to the drying unit and the first fin evaporator 18, and the second dehumidification air duct 6' is connected to the drying unit and the second fin evaporator 18'.

[0056] In some embodiments, the dehumidification air duct is further provided with an exhaust gas dehumidification control valve 14 for controlling the delivery of the humid exhaust gas to the corresponding fin evaporator. As an example, the exhaust gas dehumidification control valve 14 may be a three-way valve. As an example, the first dehumidification air duct 6 is opened by the exhaust gas dehumidification control valve 14, and the second dehumidification air duct 6' is closed, and the humid exhaust gas is controlled to be delivered to the first fin evaporator 18, or the first dehumidification air duct 6 is closed by the exhaust gas dehumidification control valve 14, and the second dehumidification air duct 6' is opened, and the humid exhaust gas is controlled to be delivered to the second fin evaporator 18'.

[0057] In some embodiments, the heat pump drying system further includes: a dry return air channel 17, which is used to transport the dry return air generated after adsorption and dehumidification of each fin evaporator to each heat pump unit.

[0058] In some embodiments, a dry return air output control valve 19 is provided on the dry return air passage 17, and the dry return air output control valve 19 allows the dry return air generated by the corresponding fin evaporator after adsorption and dehumidification to pass through. As an example, the dry return air output control valve 19 can be a three-way valve.

[0059] In some embodiments, the heat pump drying system also includes an environmental fresh air channel 16, which is connected to the drying return air channel 17. When the amount of the drying return air does not meet the requirements of the drying operation, environmental fresh air can be supplemented into the drying return air channel 17 through the environmental fresh air channel 16.

[0060] The adsorption regeneration section may include a regeneration air duct 7 and a regeneration wet exhaust gas channel, wherein the regeneration air duct 7 is used to transport the dry hot air to each of the fin evaporators to perform a desorption operation on the adsorbent. The regeneration wet exhaust gas channel is used to discharge the regeneration wet exhaust gas generated by the desorption operation. The number of the regeneration wet exhaust gas channels is connected to the number of the fin evaporators and is uniquely corresponding. This embodiment shows a first regeneration wet exhaust gas channel 8 and a second regeneration wet exhaust gas channel 8', wherein the first regeneration wet exhaust gas channel 8 is used to discharge the regeneration wet exhaust gas generated after the first adsorbent 5 is desorbed, and the second regeneration wet exhaust gas channel 8' is used to discharge the regeneration wet exhaust gas generated after the second adsorbent 5' is desorbed.

[0061] In some embodiments, the regeneration air duct 7 is further provided with a first regeneration air duct control valve 12, and the first regeneration air duct control valve 12 is used to allow the dry hot air to pass through. When the system is running, taking the first fin evaporator 18 as an example, if the moisture content of the first adsorbent 5 reaches the adsorption limit value, that is, when the adsorption is saturated, a desorption operation is required. At this time, the regeneration air duct 7 needs to be opened through the first regeneration air duct control valve 12 to enable the adsorption regeneration unit to start working.

[0062] The regeneration air duct 7 is also provided with a second regeneration air duct control valve 15, and the second regeneration air duct control valve 15 is used to control the dry hot air to be delivered to the corresponding fin evaporator. As an example, the second regeneration air duct control valve 15 is a three-way valve. As an example, when the first adsorbent 5 is saturated with adsorption, the second regeneration air duct control valve 15 controls the dry hot air to be delivered to the first fin evaporator 18 to perform a desorption operation of the first adsorbent 5; when the second adsorbent 5' is saturated with adsorption, the second regeneration air duct control valve 15 controls the dry hot air to be delivered to the second fin evaporator 18' to perform a desorption operation of the second adsorbent 5'.

[0063] Example 2

[0064] This embodiment selects the adsorbent for the heat pump drying system. Common working fluid pairs include silica gel-water, zeolite-water, molecular sieve-water and activated carbon-methanol. The temperature of the wet tail gas output after the drying operation is usually not less than 40°C, and silica gel can work under a heat source of 50°C. Compared with methanol and other traditional refrigerants, water has a greater latent heat of vaporization, so silica gel-water is selected. At the same time, the desorption temperature of silica gel-water is relatively low (about 90°C), which is similar to the temperature required for a normal drying system, and is suitable for drying with heat pump heating. In addition, silica gel has a certain degree of adhesion and can be attached to the surface of the fin evaporator by a foaming method. In summary, silica gel is selected as the adsorbent material for the fin surface.

[0065] Furthermore, the structure of silica gel is selected. Silica gel can be divided into fine-porous silica gel particles (type A), medium-porous silica gel particles (type B) and coarse-porous silica gel particles (type C), and their specific parameters are shown in Table 1.

[0066] Table 1 Pore structure parameters of three silica gels

[0067]

[0068] When selecting silica gel adsorbent suitable for heat pump drying system, it is necessary to consider both its adsorption and desorption properties.

[0069] The determination of the adsorption kinetic curve is carried out in a constant temperature and humidity chamber. An appropriate amount of treated silica gel is placed on a precision waterproof electronic balance in the constant temperature and humidity chamber, and the constant temperature T=293.15K is set. The reading of the electronic balance is recorded once at regular intervals. The adsorption kinetic curve of water vapor (adsorption percentage-time curve) is made based on the recorded time and the corresponding adsorption amount data. The relative humidity of 30% to 90% is selected to make the adsorption isotherms of different types of silica gel at different relative humidities, such as Figure 2 shown. Figure 2 Figure (a) shows the adsorption performance curve of type A silica gel. Figure 2 Figure (b) shows the adsorption performance curve of type B silica gel. Figure 2 Figure (c) is the adsorption performance curve of type C silica gel.

[0070] The desorption characteristics of silica gel were studied by temperature-programmed desorption. Before the experiment, type A, type B, type C and type C silica gel were dried at 373K for 3h, and then saturated with adsorption at relative humidity R = 70% and temperature T = 293.15K. During the experiment, a certain amount of saturated adsorption sample was placed in the differential bed in the gas chromatography column compartment, loaded into the heating furnace, connected to the gas line, opened the nitrogen valve, adjusted the mass controller to control the carrier gas flow rate to 20mL / min, set the program heating rate to 2-10K / min, and heated from 305K to 405K and kept warm for 5min. The desorption curve was obtained as shown in the figure. Figure 3 shown. Figure 3 The adsorption and desorption performance curves of three silica gels at different heating rates are shown in Figure 2. Figure 3 Figure (a) shows the adsorption and desorption performance curve of type A silica gel. Figure 3 Figure (b) shows the adsorption and desorption performance curve of type B silica gel. Figure 3 Figure (c) shows the adsorption and desorption performance curve of type C silica gel.

[0071] Depend on Figure 2 It can be seen that at a higher relative humidity (70%), the adsorption percentage (X (%)) is from large to small: C-type silica gel > B-type silica gel > A-type silica gel. Figure 3The right ordinate dX / dT and the abscissa T form a desorption performance curve. It can be seen that when the desorption heating rate is 2K / min, the desorption rate is the fastest. It takes about 25 minutes to heat from 300K to 350K, which ensures that the desorption operation is completed at 70°C. Therefore, when performing the desorption operation, the heating rate of the dry hot air output by the heat pump unit is preferably 2K / min to achieve efficient desorption, and at this preferred heating rate, the desorption percentage (dX / dT (% / K)) is from large to small: C-type silica gel>B-type silica gel>A-type silica gel. It can be seen that compared with A-type silica gel and B-type silica gel, C-type silica gel is easier to adsorb and desorb. Therefore, this embodiment selects C-type silica gel as the adsorbent for the fin evaporator.

[0072] Example 3

[0073] refer to Figure 4 This embodiment provides a control device for controlling the heat pump drying system described in Example 1. The control device includes a first detection module 100, a second detection module 200, a third detection module 300 and a main control module 400.

[0074] The first detection module 100 is used to detect the weight of each fin evaporator. As an example, the first detection module 100 may include a weight sensor, which may be correspondingly arranged at the corresponding fin evaporator. The number of the weight sensors is the same as the number of the fin evaporators, and they are uniquely corresponding. Figure 4 1 shows two weight sensors, namely a first weight sensor 101 and a second weight sensor 102. As an example, the first weight sensor 101 can be arranged at Figure 1 At the first fin evaporator 18 in the embodiment, the second weight sensor 102 may be arranged at Figure 1 At the second fin evaporator 18' in.

[0075] The second detection module 200 is used to detect the first temperature of the wet exhaust gas input to each of the fin evaporators. As an example, the second detection module may include first temperature sensors corresponding to each of the fin evaporators. The number of the first temperature sensors is the same as the number of the fin evaporators and they are uniquely corresponding. Figure 4 FIG. 2 shows two first temperature sensors, namely, the first temperature sensor 201 and the first temperature sensor 202. As an example, the first temperature sensor 201 may be arranged at Figure 1 At the first dehumidification air duct 6 in the first dehumidification air duct, the first temperature sensor 202 can be arranged at Figure 1 At the second dehumidification air duct 6'.

[0076] The third detection module 300 is used to detect the second temperature of the dry hot air output by each heat pump unit. As an example, the third detection module 300 includes second temperature sensors corresponding to each heat pump unit. The number of the second temperature sensors is the same as the number of the heat pump units and is uniquely corresponding. Figure 4 FIG. 2 shows two second temperature sensors, namely, a second temperature sensor 301 and a second temperature sensor 302. As an example, the second temperature sensor 301 may be provided at Figure 1 At the first drying hot air branch channel 10, the second temperature sensor 302 can be arranged at Figure 1 At the second dry hot air branch channel 10'.

[0077] The main control module 400 is respectively connected to the first detection module 100 , the second detection module 200 , the third detection module 300 , the heat pump unit 500 , the drying unit 600 , the dehumidification and heat exchange unit 700 , and the adsorption and regeneration unit 800 for communication.

[0078] When the desorption operation of the adsorbent of one of the fin evaporators is to be performed, the main control module 400 is used to obtain the weight of the corresponding fin evaporator measured by the first detection module 100, and obtain the moisture content of the adsorbent based on the weight, and compare the moisture content with the desorption completion standard value. The moisture content can also be called moisture content.

[0079] Combination Figure 1 and Figure 4 , taking the first fin evaporator 18 as an example, when the desorption operation of the first adsorbent 5 is to be performed, the main control module 400 is used to obtain the weight of the first fin evaporator 18 measured by the first detection module 100, and obtain the moisture content of the first adsorbent 5 based on the weight, and compare the moisture content with the desorption completion standard value. Among them, the desorption completion standard value refers to the moisture content when the desorption is completed. As an example, the desorption completion standard value can be set to 10%. When the calculated moisture content is ≤10%, it means that the desorption is completed. The moisture content of the adsorbent can be calculated by the following formula:

[0080] Moisture content % = (W 总重 -W 初始 ) / W 总重 )×100%;

[0081] Where W 总重 Represents the total weight of the finned evaporator after adsorption dehumidification, W 初始 Represents the initial weight of the finned evaporator when no adsorption dehumidification is performed.

[0082] When the calculated moisture content does not reach the desorption completion standard value, that is, when desorption is not completed, the main control module 400 is also used to obtain the first temperature measured by the second detection module 200, and based on the first temperature and the regeneration temperature (Tzs) of the adsorbent, the evaporation temperature (Te), condensation temperature (Tc) and compressor frequency of the corresponding heat pump unit are set, and the adsorption regeneration part is controlled to perform desorption operation on the adsorbent of the corresponding fin evaporator.

[0083] As an example, combining Figure 1 and Figure 4 When the calculated moisture content of the first adsorbent 5 is less than 10%, the main control module 400 is further used to obtain the first temperature (T6) at the first dehumidification air duct 6, and set the evaporation temperature (Te) of the first evaporator 1, the condensation temperature (Tc) of the first condenser 3 and the frequency of the first compressor 2 in the heat pump unit I based on the first temperature (T6) and the regeneration temperature (Tzs) of the first adsorbent 5, wherein Te = T6-5°C, Tc = Tzs+10°C, and the frequency of the first compressor 2 is gradually increased, so that the temperature rise rate of the dry hot air output by the heat pump unit I is maintained at 2K / min. The first regeneration air duct control valve 12 is opened, and the second regeneration air duct control valve 15 is controlled to transport the dry hot air to the first fin evaporator 18, and the first adsorbent 5 is desorbed.

[0084] When the desorption operation of the adsorbent of one of the fin evaporators is completed, the main control module 400 is also used to control the adsorption regeneration part to stop working, and obtain the second temperature measured by the third detection module 300, and set the condensing temperature of the corresponding heat pump unit based on the target drying temperature, and adjust the compressor frequency of the corresponding heat pump unit based on the second temperature and the target drying temperature, until the temperature difference between the second temperature and the target drying temperature reaches the target value, and then control the drying part and the dehumidification heat exchange part to start working.

[0085] As an example, combining Figure 1 and Figure 4When the first adsorbent 5 completes desorption, the main control module 400 is also used to close the first regeneration air duct control valve 12, obtain the second temperature (T10) at the first dry hot air branch channel 10, and set the condensation temperature (Tc) of the first condenser 3 based on the target drying temperature (Tgz): Tc = Tgz + 10 ° C. Control the operation of the heat pump unit I to determine whether the second temperature (T10) reaches the target drying temperature (Tgz). If T10 < Tgz, increase the frequency of the first compressor 2. If T10 ≥ Tgz, determine whether the difference between T10 and Tgz is not less than 1 ° C. If T10-Tgz ≥ 1 ° C, the first compressor 2 can maintain a fixed frequency operation, otherwise the frequency of the first compressor 2 needs to be reduced. After the frequency of the first compressor 2 is set, the dry hot air output control valve 11 is controlled to open, and the exhaust gas dehumidification control valve 14 is controlled to open the first dehumidification air duct 6 to perform drying operation and dehumidification adsorption operation.

[0086] Example 4

[0087] refer to Figure 5 This embodiment provides a control method for controlling the heat pump drying system described in Embodiment 1, and the control method comprises the following steps:

[0088] S1: Control the heat pump unit of the heat pump part to heat the dry return air to provide dry hot air;

[0089] S2: Controlling the drying section to perform a drying operation using the dry hot air and outputting wet tail gas;

[0090] S3: Controlling the finned evaporator of the dehumidification heat exchange part to perform adsorption dehumidification on the humid exhaust gas and generate heat and the dry return air, wherein the heat is absorbed by the heat pump unit;

[0091] S4: Controlling the adsorption regeneration unit to utilize the dry hot air to perform a desorption operation on the adsorbent on the fin surface of the fin evaporator.

[0092] In some embodiments, before performing step S2, the control method also includes step S2-0: setting the condensing temperature of the corresponding heat pump unit based on the target drying temperature, and regulating the compressor frequency of the corresponding heat pump unit based on the second temperature of the dry hot air output by the corresponding heat pump unit and the target drying temperature, until the temperature difference between the second temperature and the target drying temperature reaches the target value, and then controlling the drying part to start working.

[0093] In some embodiments, before performing step S4, the control method further includes step S4-0: based on the first temperature of the wet exhaust gas input to the corresponding fin evaporator and the regeneration temperature of the corresponding adsorbent, the evaporation temperature, condensation temperature and compressor frequency of the corresponding heat pump unit are set. Particularly preferably, the frequency of the compressor is gradually increased, and the temperature increase rate of the dry hot air output by the corresponding heat pump unit is maintained at 2K / min.

[0094] In some embodiments, each heat pump unit operates alternately, and each fin evaporator also operates alternately. As an example, one of the heat pump units is a first heat pump unit, and the fin evaporator corresponding to the first heat pump unit is a first fin evaporator; the other heat pump unit is a second heat pump unit, and the fin evaporator corresponding to the second heat pump unit is a second fin evaporator, the first heat pump unit and the second heat pump unit operate alternately, and the first fin evaporator and the second fin evaporator operate alternately.

[0095] refer to Figure 6 In some embodiments, the fin surface of the first fin evaporator has a first adsorbent, and the fin surface of the second fin evaporator has a second adsorbent; the first heat pump unit and the second heat pump unit are operated alternately, and the method of alternating the operation of the first fin evaporator and the second fin evaporator comprises the following steps:

[0096] S10: controlling the first heat pump unit to start, and detecting the moisture content of the second adsorbent, and if the moisture content of the second adsorbent has not reached the desorption completion standard value, performing a desorption operation on the second adsorbent;

[0097] S20: When it is detected that the moisture content of the second adsorbent reaches a desorption completion standard value, the first heat pump unit and the first fin evaporator are controlled to start operating, and during the operation, the moisture content of the first adsorbent is detected;

[0098] S30: When it is detected that the moisture content of the first adsorbent reaches the adsorption limit value, the first heat pump unit is controlled to be turned off, and the second heat pump unit is controlled to be turned on to perform a desorption operation on the first adsorbent;

[0099] S40: When it is detected that the moisture content of the first adsorbent reaches a desorption completion standard value, the second heat pump unit and the second fin evaporator are controlled to operate, and during the operation, the moisture content of the second adsorbent is detected;

[0100] S50: When it is detected that the moisture content of the second adsorbent reaches the adsorption limit value, the second heat pump unit is controlled to be shut down.

[0101] Combination Figure 1 and Figure 7Taking the heat pump unit including heat pump unit I (referred to as heat pump I) and heat pump unit II (referred to as heat pump II), and the corresponding fin evaporators including a first fin evaporator (having a first adsorbent 5) and a second fin evaporator (having a second adsorbent 5') as an example, the control logic of the heat pump drying system is described in detail as follows.

[0102] (1) Turn on heat pump I.

[0103] (2) Performing a desorption operation on the second adsorbent 5', that is, entering the adsorbent regeneration process corresponding to the heat pump II.

[0104] First, the moisture content of the second adsorbent 5' corresponding to the heat pump II is detected. If the moisture content is ≤10%, the desorption operation is completed, and the heat pump operation process of the heat pump I is directly entered, that is, the drying process of the heat pump I is entered. In addition, the temperature of the second adsorbent 5' can also be detected. If the temperature of the second adsorbent 5' is higher or lower than the target temperature, the temperature of the second adsorbent 5' will be adjusted to achieve the target adsorption rate.

[0105] If the moisture content is greater than 10%, the evaporation temperature Te=T6-5°C and the condensation temperature Tc=Tzs+10°C that the heat pump I needs to reach are set, wherein T6 represents the temperature at the first dehumidification air duct 6, and Tzs represents the regeneration temperature of the second adsorbent 5'. The frequency of the first compressor 2 of the heat pump I is gradually increased to maintain the condensation temperature Tc at a growth rate of 2K / min, thereby maintaining the heating rate of the dry hot air output by the heat pump unit I at a growth rate of 2K / min.

[0106] The first regeneration air duct control valve 12 and the second regeneration air duct control valve 15 are opened to allow the dry hot air to heat and desorb the second adsorbent 5'. The temperature and humidity of the second adsorbent 5' are detected again until the moisture content reaches ≤10%, and the desorption is completed. The first regeneration air duct control valve 12 is closed to enter the heat pump operation process of the heat pump I.

[0107] (3) The temperature (T10) at the first drying hot air branch channel 10 is detected, and the final condensation temperature of the heat pump unit I is set to Tc = Tgz + 10°C, where Tgz is the drying temperature, and the heat pump I is running. In addition, the temperature (T6) of the first dehumidification air duct 6 can also be detected to determine the evaporation temperature Te = T6-5°C.

[0108] It is determined whether T10 meets the drying temperature requirement at this time. If T10 < Tgz, the frequency of the first compressor 2 is increased. If T10 ≥ Tgz, it is determined whether the difference between T10 and Tgz is not less than 1°C. If T10-Tgz ≥ 1°C, the first compressor 2 can maintain a fixed frequency operation, otherwise it is necessary to reduce the frequency of the first compressor 2. After the heat pump I provides the required dry hot air, the dry hot air output control valve 11 is opened.

[0109] The temperature and humidity of the first adsorbent 5 corresponding to the heat pump I are detected. If the moisture content is less than 55%, the first compressor 2 continues to run and performs a drying operation. If the moisture content is ≥55%, the adsorption limit of type C silica gel is reached, and the heat pump II needs to be turned on and the heat pump I is turned off to perform a desorption operation of the first adsorbent 5, which is the adsorbent regeneration process corresponding to the heat pump I.

[0110] (4) Detect the temperature and humidity of the first adsorbent 5. If the moisture content is ≤10%, desorption is completed and the heat pump operation process of the heat pump II is directly entered; if the moisture content is >10%, set the evaporation temperature Te = T6'-5°C and the condensation temperature Tc = Tzs+10°C that the heat pump II needs to reach, where T6' represents the temperature at the second dehumidification air duct 6', and Tzs represents the regeneration temperature of the first adsorbent 5. The frequency of the second compressor 2' in the system is gradually increased, so that the condensation temperature Tc is maintained at a growth rate of 2K / min, thereby maintaining the temperature rise rate of the dry hot air output by the heat pump unit II at a growth rate of 2K / min.

[0111] The first regeneration air duct control valve 12 and the second regeneration air duct control valve 15 are opened to allow the dry hot air to heat and desorb the first adsorbent 5. The temperature and humidity of the first adsorbent 5 are detected again until the moisture content reaches ≤10%, and the desorption is completed. The first regeneration air duct control valve 12 is closed to enter the heat pump operation process of the heat pump II, that is, the heat pump II drying process.

[0112] (5) Detect the temperature (T6') of the second dehumidification air duct 6' and the temperature (T10') at the second dry hot air branch channel 10', set the final condensation temperature of the heat pump unit II to Tc = Tgz + 10°C, where Tgz is the drying temperature, and the heat pump II is running. Determine whether T10' meets the drying temperature requirement at this time. If T10'<Tgz, increase the frequency of the second compressor 2'. If T10'≥Tgz, determine whether the difference between T10' and Tgz is not less than 1°C. If T10'-Tgz≥1°C, the second compressor 2' can maintain fixed frequency operation, otherwise the frequency of the second compressor 2' needs to be reduced. After the heat pump II provides the dry hot air that meets the requirements, open the dry hot air output control valve 11.

[0113] The temperature and humidity of the second adsorbent 5' corresponding to the heat pump II are detected. If the moisture content is less than 55%, the second compressor 2' continues to run and performs a drying operation. If the moisture content is ≥55%, the adsorption limit of type C silica gel is reached, and the heat pump I needs to be turned on, the heat pump II is turned off, and the desorption operation of the second adsorbent 5' is performed.

[0114] Based on the control logic of heat pump I and heat pump II above, the dual heat pump system can continuously supply hot air that meets the drying requirements, and can also realize continuous and efficient adsorption and desorption processes of the adsorbent.

[0115] The performance of the heat pump drying system using adsorbent for adsorption dehumidification and dehumidification waste heat recovery in Example 1 of the present application (hereinafter referred to as "the system of the present invention") is compared with the performance of the heat pump dehumidification drying system without adsorbent (hereinafter referred to as "the existing system").

[0116] According to the enthalpy and humidity properties of air, the change of its dew point temperature with temperature and humidity is shown in Table 2 below.

[0117] Table 2 Dew point temperature changes with temperature and humidity

[0118]

[0119] The heat pump system simulation adopts the commonly used state point method, and the specific assumptions are shown in Table 3.

[0120] Table 3 Parameter settings

[0121] parameter Settings Remark Evaporation temperature <![CDATA[T hs -5℃]]> 5℃ below heat source Condensation temperature <![CDATA[T sp +10℃]]> 10℃ higher than output Compressor suction superheat 5℃ 5℃ higher than evaporation temperature Condenser outlet subcooling 2℃ 2℃ below condensation temperature <![CDATA[Compressor adiabatic efficiency (η is )]]> 0.7～0.9

[0122] The energy efficiency calculation formula of the heat pump system is as follows:

[0123] Compressor suction flow (m r,COM ) is calculated by the compressor exhaust volume (V COM )、Speed(N COM ), suction density (ρ r,Eout ), the compressor outlet enthalpy is determined by the suction enthalpy (h r,COMin ), adiabatic efficiency (η is ), isentropic compression enthalpy (h r,is ), compressor outlet enthalpy (h r,COMout ), the compressor power consumption (P) is calculated by the refrigerant flow rate and the compressor inlet and outlet enthalpy values. The heating capacity (Q) of the heat pump system is determined by the refrigerant flow rate and the condenser inlet and outlet enthalpy values. Therefore, the energy efficiency (COP) of the heat pump system is the ratio of heating capacity to power consumption, as shown in formula (3).

[0124]

[0125] Q=m r (h r,COMout -h r,Cout )=m w c p,w (T w,out -T w,in ) (2)

[0126]

[0127] According to the above simulation method, Figure 8 The system energy efficiency COP of the system of the present invention and the existing system under different drying conditions and the system energy efficiency COP of the existing system under different relative humidity conditions are compared. Fig. 9 The heating capacity of the system of the present invention and the existing system under different drying conditions and the heating capacity of the existing system under different relative humidity conditions are compared. Since the system of the present invention adopts the adsorption principle, the evaporation temperature is not affected by the relative humidity (i.e., it is not affected by the dew point temperature). Figure 8 and Fig. 9 In the present invention, the system only involves a performance curve when the relative humidity is 80%. However, the existing system requires the heat pump evaporation temperature to operate below the dew point, and therefore involves performance curves under different humidity conditions.

[0128] refer to Figure 8 Since the system of the present invention uses an adsorbent, it can directly dehumidify at the dry-bulb temperature, while the existing system needs to reach the dew point temperature for dehumidification. Therefore, as the humidity decreases, the existing system needs to reach a lower evaporation temperature to reach the dew point temperature. Therefore, under the condition of relative humidity below 80%, the performance of the existing system is lower than the performance of the system of the present invention, and as the dry-bulb temperature increases, the performance improvement effect of the system of the present invention is better. Specifically, under the condition of 50% relative humidity, the performance of the system of the present invention is improved by 15.7% to 45.1%, under the condition of 60% relative humidity, the performance of the system of the present invention is improved by 9.1% to 28.1%, and under the condition of 70% relative humidity, the performance of the system of the present invention is improved by 3.1% to 13.6%. Under the condition of 80% relative humidity, the performance of the system of the present invention is similar to that of the existing system.

[0129] refer to Fig. 9 , comparing the heating capacity of the system of the present invention with that of the existing system, under the condition of 50% relative humidity, the heating capacity of the system of the present invention is increased by 26.6% to 32.1%, under the condition of 60% relative humidity, the heating capacity of the system of the present invention is increased by 14.6% to 18.8%, and under the condition of 70% relative humidity, the heating capacity of the system of the present invention is increased by 4.8% to 8.6%. Under the condition of 80% relative humidity, the performance of the system of the present invention is similar to that of the existing system. Therefore, under the same drying heating demand, compared with the existing system, the system of the present invention can reduce the capacity of the heat pump system accordingly. Due to the improvement of system performance, the initial investment cost of the heat pump system can be reduced.

[0130] Finally, it should be understood that the embodiments described in this application are only used to illustrate the principles of the embodiments of the present application. Other variations may also fall within the scope of the present application. Therefore, as an example and not a limitation, the alternative configurations of the embodiments of the present application may be considered to be consistent with the teachings of the present application. Accordingly, the embodiments of the present application are not limited to the embodiments explicitly introduced and described in the present application.

Claims

1. A heat pump drying system, characterized in that: include: The heat pump unit includes at least one heat pump unit, and the heat pump unit is used to provide dry hot air; A drying section, used for performing a drying operation using the dry hot air and outputting a wet tail gas; The dehumidification heat exchange part includes at least one fin evaporator, and the number of the fin evaporators is the same as the number of the heat pump units, wherein: The fin surface of each fin evaporator is provided with an adsorbent, and the adsorbent is used to adsorb and dehumidify the humid exhaust gas and generate heat and dry return air. When the system is running, the heat is absorbed by the heat pump unit, and the dry return air is heated by the heat pump unit to form the dry hot air; the adsorption regeneration part is used to utilize the dry hot air to desorb the adsorbent.

2. The heat pump drying system according to claim 1, characterized in that: Each of the heat pump units includes an evaporator, a compressor, a condenser and a throttle valve that are cyclically connected. When the system is running, the heat generated by adsorption dehumidification is absorbed by the evaporator, and the condenser is used to heat the dry return air.

3. The heat pump drying system according to claim 1, characterized in that: The drying section comprises: A dried space, used for containing the dried material; A drying hot air channel, one end of which is connected to each of the heat pump units, and the other end of which is connected to the dried space and the adsorption regeneration part; The wet exhaust gas channel has one end connected to the dried space and the other end connected to the dehumidification heat exchange part.

4. The heat pump drying system according to claim 3, characterized in that: The dry hot air channel is also provided with a dry hot air output control valve, and the dry hot air output control valve allows the dry hot air output by the corresponding heat pump unit to pass through.

5. The heat pump drying system according to claim 1, characterized in that: The dehumidification heat exchange part further includes: a dehumidification air duct, which is connected with the drying part and each of the fin evaporators and is used to transport the humid exhaust gas to each of the fin evaporators.

6. The heat pump drying system according to claim 5, characterized in that: The dehumidification air duct is also provided with: an exhaust gas dehumidification control valve for controlling the delivery of the humid exhaust gas to the corresponding fin evaporator.

7. The heat pump drying system according to claim 1, characterized in that: The adsorption regeneration unit comprises: A regeneration air duct, used for conveying the dry hot air to each of the fin evaporators to perform a desorption operation on the adsorbent; The regenerated wet exhaust gas channel is used to discharge the regenerated wet exhaust gas generated by the desorption operation.

8. The heat pump drying system according to claim 7, characterized in that: The regeneration air duct is also provided with: A first regeneration air duct control valve, used for allowing the dry hot air to pass through; The second regeneration air duct control valve is used to control the dry hot air to be delivered to the corresponding fin evaporator.

9. The heat pump drying system according to claim 1, characterized in that: The heat pump drying system further comprises: a dry return air channel, which is used to transport the dry return air generated after the adsorption and dehumidification of each fin evaporator to each heat pump unit.

10. The heat pump drying system according to claim 9, characterized in that: The dry return air channel is provided with a dry return air output control valve, and the dry return air output control valve allows the dry return air generated after adsorption and dehumidification of the corresponding fin evaporator to pass through.

11. The heat pump drying system according to any one of claims 1 to 10, characterized in that: The adsorbent is coarse-pored silica gel particles, and the mesh number of the coarse-pored silica gel particles is 20-29, the pore size is 10nm-11nm, and the specific surface area is 350m 2 / g~360m 2 / g, pore volume is 0.9cm 3 / g~1.0cm 3 / g.

12. A control device, characterized in that: The control device is used to control the heat pump drying system according to any one of claims 1 to 11, and the control device includes: A first detection module is used to detect the weight of each fin evaporator; A second detection module, used for detecting a first temperature of the wet exhaust gas input to each of the fin evaporators; A third detection module is used to detect the second temperature of the dry hot air output by each heat pump unit; A main control module is respectively connected to the first detection module, the second detection module, the third detection module, the heat pump unit, the drying part, the dehumidification heat exchange part and the adsorption regeneration part; Wherein, when the desorption operation of the adsorbent of one of the fin evaporators is to be performed, the main control module is used to obtain the weight of the corresponding fin evaporator measured by the first detection module, and obtain the moisture content of the adsorbent based on the weight, and compare the moisture content with the desorption completion standard value; When the moisture content does not reach the desorption completion standard value, the main control module is further used to obtain the first temperature measured by the second detection module, and set the evaporation temperature, condensation temperature and compressor frequency of the corresponding heat pump unit based on the first temperature and the regeneration temperature of the adsorbent, and control the adsorption regeneration unit to perform desorption operation on the adsorbent of the corresponding fin evaporator; When the desorption operation of the adsorbent of one of the fin evaporators is completed, the main control module is also used to control the adsorption regeneration part to stop working, and obtain the second temperature measured by the third detection module, and set the condensing temperature of the corresponding heat pump unit based on the target drying temperature, and adjust the compressor frequency of the corresponding heat pump unit based on the second temperature and the target drying temperature, until the temperature difference between the second temperature and the target drying temperature reaches the target value, and then control the drying part and the dehumidification heat exchange part to start working.

13. The control device according to claim 12, characterized in that: The first detection module includes weight sensors corresponding to the fin evaporators; the second detection module includes first temperature sensors corresponding to the fin evaporators; and the third detection module includes second temperature sensors corresponding to the heat pump units.

14. A control method, characterized in that: The control method is used to control the heat pump drying system according to any one of claims 1 to 11, and the control method comprises: Controlling the heat pump unit of the heat pump section to heat the dry return air to provide dry hot air; Controlling the drying section to perform drying operation using the dry hot air and outputting the wet tail gas; Controlling the finned evaporator of the dehumidification heat exchange part to perform adsorption dehumidification on the humid tail gas and generate heat and the dry return air, wherein the heat is absorbed by the heat pump unit; The adsorption regeneration unit is controlled to perform a desorption operation on the adsorbent on the fin surface of the fin evaporator by using the dry hot air.

15. The control method according to claim 14, characterized in that: One of the heat pump units is a first heat pump unit, and the fin evaporator corresponding to the first heat pump unit is a first fin evaporator; the other heat pump unit is a second heat pump unit, and the fin evaporator corresponding to the second heat pump unit is a second fin evaporator; the first heat pump unit and the second heat pump unit operate alternately, and the first fin evaporator and the second fin evaporator operate alternately.

16. The control method according to claim 15, characterized in that: The fin surface of the first fin evaporator has a first adsorbent, and the fin surface of the second fin evaporator has a second adsorbent; the first heat pump unit and the second heat pump unit are operated alternately, and the method of the first fin evaporator and the second fin evaporator being operated alternately includes: Controlling the first heat pump unit to start, and detecting the moisture content of the second adsorbent, and if the moisture content of the second adsorbent has not reached the desorption completion standard value, performing a desorption operation on the second adsorbent; When it is detected that the moisture content of the second adsorbent reaches a desorption completion standard value, the first heat pump unit and the first fin evaporator are controlled to start operating, and during the operation, the moisture content of the first adsorbent is detected; When it is detected that the moisture content of the first adsorbent reaches the adsorption limit value, the first heat pump unit is controlled to be turned off, and the second heat pump unit is controlled to be turned on to perform a desorption operation on the first adsorbent; When it is detected that the moisture content of the first adsorbent reaches a desorption completion standard value, the second heat pump unit and the second fin evaporator are controlled to operate, and during the operation, the moisture content of the second adsorbent is detected; When it is detected that the moisture content of the second adsorbent reaches the adsorption limit value, the second heat pump unit is controlled to be shut down.

17. The control method according to claim 14, characterized in that: Before controlling the drying part to perform a drying operation using the dry hot air, the control method further includes: setting a condensing temperature of the corresponding heat pump unit based on a target drying temperature, and regulating the compressor frequency of the corresponding heat pump unit based on a second temperature of the dry hot air output by the corresponding heat pump unit and the target drying temperature, until the temperature difference between the second temperature and the target drying temperature reaches a target value, and then controlling the drying part to start working.

18. The control method according to claim 14, characterized in that: Before performing the desorption operation, the control method also includes: setting the evaporation temperature, condensation temperature and compressor frequency of the corresponding heat pump unit based on the first temperature of the wet exhaust gas input to the corresponding fin evaporator and the regeneration temperature of the corresponding adsorbent; preferably, the compressor frequency is gradually increased so that the heating rate of the dry hot air output by the corresponding heat pump unit is maintained at 2K / min.

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