Superimposed double-circulation low-temperature drying system, use method and application

Abstract

The present invention belongs to the field of drying systems, and specifically relates to a superimposed double-circulation low-temperature drying system. The drying system is a system with forward Carnot cycle heating and reverse Carnot cycle refrigeration and dehumidification functions. The drying system provided by the present invention includes: a first refrigeration system, a second refrigeration system, a circulating fan, and an air distribution and deflecting plate; a group of first condensers, first evaporators, and second evaporators are arranged on both sides of the circulating fan; the first gas-liquid separator and the first refrigeration compressor of the first refrigeration system are connected to the first condenser in sequence; the second gas-liquid separator and the second refrigeration compressor of the second refrigeration system are connected to the second condenser in sequence; and an air distribution and deflecting plate is arranged in the drying chamber. The drying system of the present invention has the following advantages: the material to be dried is highly safe and does not mildew; less loss of nutrients; energy saving; and also has the characteristics of fast drying speed, consistent drying speed, and environmental protection.

Description

Technical Field

[0001] The present invention belongs to the field of drying systems, and in particular relates to a superimposed double-circulation low-temperature drying system. The drying system is a system with forward Carnot cycle heating and reverse Carnot cycle refrigeration and dehumidification functions. Background Art

[0002] At present, the drying of Chinese herbal medicines, aquatic products, fruits and vegetables mainly adopts several methods such as air drying, natural drying, natural gas heating drying, electric heating drying, heat pump drying and vacuum freeze drying.

[0003] Air drying means placing the material to be dried indoors, using fans for forced ventilation to introduce outdoor air into the room and discharge the wet air generated by the material to be dried indoors to the atmosphere. Although the drying temperature required by the above drying method is relatively low and the loss of nutrients in the material to be dried is small, its drying efficiency is very low. In addition, the above drying method is greatly affected by the weather. In the southern region with relatively high relative humidity, as well as in rainy weather and when the outdoor relative humidity is relatively high, the above drying method not only leads to too long drying time, but also easily breeds bacteria, fungi and other microorganisms, and the material to be dried is easy to mold and deteriorate under the action of microorganisms, and loses its due value.

[0004] Natural drying means placing the material to be dried in an outdoor natural environment and using the sun's radiation heat exchange to evaporate the moisture in the material to be dried. Compared with air drying, this method does not require indoor space and has a relatively low investment cost. However, its disadvantage is that it requires a large amount of outdoor open space and is still greatly affected by the weather and environment. During the day, the sun shines, and at night, water mist falls directly on the material to be dried, especially in rainy weather, which often causes a large amount of material to be dried to mold and deteriorate.

[0005] The principles of gas drying and electric heating drying are similar. Both use high temperature to make the material to be dried lose water quickly to achieve the purpose of drying. The difference is that gas drying uses the high temperature generated by gas combustion to heat the material to be dried; electric heating uses the high temperature generated by the electric heating tube to heat the material to be dried. The loss of nutrients in the material to be dried during the drying process is directly related to the drying temperature. Although the above two drying methods have fast drying speeds and are not affected by the environment and climate, the effective ingredients and nutritional value of the material to be dried are almost completely lost due to the excessively high drying temperature. From the perspective of nutrient retention, the above drying methods are not advisable.

[0006] The heat pump drying temperature is higher than that of air drying and natural drying, and is not affected by the weather. It is slower than natural gas and electric heating drying, but the drying temperature is much lower, and the energy utilization coefficient is much higher than that of natural gas and electric heating drying. However, it is still a kind of drying, but the drying temperature is between 50~80℃, and the loss of effective ingredients and nutritional value of the material to be dried is relatively small. The most basic principle of drying is the loss of water in the material to be dried. At present, although there are heat pump drying devices that use refrigeration systems for dehumidification, they do not recover all heat, which leads to a low energy utilization coefficient in the drying process. Drying only uses fans to circulate the air system in the drying chamber to achieve the purpose of drying, so the drying speed is still very slow.

[0007] Vacuum freeze drying is to use the refrigeration system to quickly freeze the material to be dried, so that the water content of the material to be dried freezes, and then use the vacuum pump to evacuate the material to be dried so that the frozen material to be dried is in a vacuum state. At this time, the ice of the material to be dried will sublimate to produce water vapor, and then use the evaporator of the refrigeration system to condense the water vapor to maintain the vacuum state of the material to be dried, so as to ensure the sustainable sublimation of the ice of the material to be dried and achieve the purpose of drying. When the freezing temperature of the material to be dried reaches -30℃, only 97% of the water in it freezes. To freeze 100% of the water in the material to be dried, it needs to reach -60℃. Therefore, although the loss of effective ingredients and nutrients of the material to be dried after drying does not exceed 5%, the energy consumption of the refrigeration system is extremely high, and the initial investment is expensive in the vacuum environment. It is precisely because of the high energy consumption and high initial investment cost that vacuum freeze drying is currently only used in special fields such as medicine and microorganisms.

[0008] To sum up, if we can overcome the existing technical bottlenecks and invent a low-temperature drying device with a relatively low drying temperature, which is not affected by the ambient weather during the drying process, has a refrigeration system evaporator for dehumidification and can achieve 100% waste heat recovery, we can solve the problems of low efficiency and corruption of the materials to be dried by the traditional air drying and natural drying methods, solve the problem of loss of effective ingredients and nutritional value of the materials to be dried by natural gas and electric heating drying methods, solve the problem of large loss of effective ingredients and nutritional value, slow drying speed and low efficiency caused by high drying temperature of heat pumps and inability to recover full heat, and solve all the problems of existing drying methods such as high energy consumption and expensive initial investment of vacuum freeze drying. This will play a huge role in promoting the drying of Chinese herbal medicines, aquatic products, fruits and vegetables, and grains, and will also help reduce the expensive costs and investment in fresh storage and transportation. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a low-temperature drying system with relatively low drying temperature, which is not affected by the ambient weather during the drying process, has a refrigeration system evaporator dehumidification and can achieve 100% waste heat recovery.

[0010] The stacked double-circulation low-temperature drying system provided by the present invention comprises: a first refrigeration system, a second refrigeration system, a circulating fan, and an air distribution and guide plate;

[0011] The first refrigeration system includes: a first gas-liquid separator, a first refrigeration compressor, two first condensers located on both sides of the circulating fan, and two first evaporators;

[0012] The outlet of the first gas-liquid separator is connected to the first refrigeration compressor, and the first refrigeration compressor is divided into two branches, which lead to the first condenser located on both sides of the circulation fan respectively;

[0013] The first condenser is connected to the first evaporator through a pipeline;

[0014] Two pipelines at the inlet of the first gas-liquid separator are respectively connected to the two first evaporators on both sides of the circulation fan;

[0015] The second refrigeration system includes: a second gas-liquid separator, a second refrigeration compressor, two second condensers, and two second evaporators located on both sides of the circulating fan;

[0016] The two second evaporators are respectively located below or on either side of the two first evaporators.

[0017] The second evaporator on one side is connected to the second condenser, and the second evaporator on the other side is also connected to another second condenser. The pipelines of the two second condensers are connected to the second refrigeration compressor and the second gas-liquid separator in turn after being converged; the two pipelines at the inlet of the second gas-liquid separator are respectively connected to the two second evaporators on both sides of the circulation fan;

[0018] The first condenser, the first evaporator, the circulating fan and the second condenser are surrounded by a protective structure to form a drying chamber; an air distribution and guide plate is arranged between the circulating fan and the second condenser, and both ends of the air distribution and guide plate are connected to the two sides of the protective structure.

[0019] Preferably, a first throttle valve is respectively provided on the pipeline between the first evaporator and the first condenser;

[0020] Preferably, a first high-pressure liquid storage tank is respectively provided on the pipeline between the first condenser and the first evaporator.

[0021] A second throttle valve is respectively arranged on the pipeline between the second evaporator and the second condenser;

[0022] Preferably, a second high-pressure liquid storage tank is respectively provided on the pipeline between the second evaporator and the second condenser.

[0023] Two first condensers and two first evaporators are symmetrically arranged on both sides of the circulation fan from inside to outside.

[0024] Two second evaporators are symmetrically arranged on both sides of the circulation fan, and the second evaporators are respectively located below the two first evaporators.

[0025] The two sides of the air distribution and guide plate are porous plates, and the two ends are sealing plates without holes.

[0026] The first condenser is a finned condenser;

[0027] Preferably, the second condenser is two sets of shelf-type heat exchangers;

[0028] The first evaporator is a finned evaporator;

[0029] Preferably, the second evaporator is a finned evaporator;

[0030] Preferably, the second condenser is two sets of flat plate freezers, and the second condenser is located on both sides of the air supply port of the circulating fan;

[0031] Preferably, two circulation fans are provided in the drying chamber.

[0032] Regarding the arrangement of the first evaporator and the second evaporator, they can be arranged in the following ways:

[0033] The first evaporator is located above the second evaporator and the first evaporator is located on a supporting structure shared by the second evaporator and the second evaporator;

[0034] Alternatively, the first evaporator is located above the second evaporator and the first evaporator and the second evaporator have a supporting structure of the first evaporator; and a corresponding supporting structure is located below the second evaporator;

[0035] Alternatively, the first evaporator is arranged in parallel with the second evaporator, and the first evaporator is located outside the second evaporator.

[0036] Preferably, the method for using the above-mentioned superimposed double-circulation low-temperature drying system comprises the following steps:

[0037] S1: Open the enclosure door of the drying chamber, place the material to be dried above the second condenser, and then close the enclosure door;

[0038] S2: Start the first refrigeration system, the second refrigeration system and the circulating fan respectively. The circulating fan starts to run, and the air discharged by it passes over the upper surface of the material to be dried and the lower surface of the second condenser. The superheated refrigerant gas discharged by the second refrigeration compressor enters the second condenser. At this time, the high-pressure superheated refrigerant gas discharged by the second refrigeration compressor passes through the second condenser and transfers heat to the material to be dried, so that the temperature of the lower part of the material to be dried increases;

[0039] S3: The high-pressure superheated refrigerant gas condenses into high-pressure liquid and enters the second high-pressure liquid storage tank through the high-pressure refrigeration pipeline. The high-pressure refrigerant liquid coming out of the second high-pressure liquid storage tank is throttled and depressurized by the second throttle valve to become a low-pressure refrigerant liquid and enters the second evaporator. After absorbing the hot and humid air blown by the circulating fan and passing over the upper surface of the material to be dried and the lower surface of the second condenser, the low-pressure refrigerant liquid evaporates into low-pressure refrigerant gas. After the temperature and humidity of the hot and humid air decrease, it becomes low-temperature and low-humidity air and passes through the first condenser. Since the first refrigeration system is also started, the low-temperature and low-humidity air absorbs the heat of the superheated refrigerant gas discharged by the first refrigeration compressor. The temperature of the low-temperature and low-humidity air increases, and the relative humidity decreases. It is sucked in by the circulating fan and continues to pass over the upper surface of the material to be dried and the second condenser. The lower surface of the dryer, while the refrigerant in the second condenser transfers heat to the low-temperature and low-humidity air in the first condenser, becomes a high-pressure refrigerant liquid, enters the first high-pressure liquid storage tank, is throttled and depressurized by the first throttle valve, becomes a low-pressure refrigerant liquid, enters the first evaporator, and the low-pressure refrigerant liquid absorbs the air blown by the circulating fan and passes through the hot and humid air on the upper surface of the material to be dried and the lower surface of the circulating fan. The low-pressure refrigerant liquid evaporates into a low-pressure refrigerant gas. The hot and humid air temperature and humidity are reduced to become low-temperature and low-humidity air, which is also heated by the first condenser. The low-temperature and low-humidity air absorbs the heat of the superheated refrigerant gas discharged by the first refrigeration compressor, and the temperature of the low-temperature and low-humidity air increases, and the relative humidity decreases. Driven by the circulating fan, it continues to pass over the upper surface of the material to be dried and the lower surface of the second condenser;

[0040] S4: In this way, the steps of S2 and S3 are continuously cycled, and the material to be dried is continuously heated by the low-temperature, humid hot air blown out by the fan and the heat of the second condenser, and its moisture is continuously evaporated into hot and humid water vapor. In addition, under the action of the air distribution and air guide plate, the wind speed of the air distribution and air guide plate is stable, the air volume passing through the dried material is uniform, and the drying effect is consistent. Then, the air is condensed and precipitated through the evaporator of the first independent refrigeration system and the second independent refrigeration system, thereby achieving the purpose of drying the dried material.

[0041] The application of the above-mentioned superimposed double-circulation low-temperature drying system in the drying of Chinese herbal medicines, aquatic products, fruits and vegetables is also within the scope of protection of the present invention.

[0042] The beneficial effects of the present invention are:

[0043] (1) The materials to be dried are highly safe and free of mildew:

[0044] Due to the use of the drying system with heating and dehumidification functions in the present invention, the drying process is not affected by the environmental climate, reducing the problem of corruption and deterioration caused by bacteria growth due to the influence of climate in other drying methods, and improving the safety of the material to be dried;

[0045] (2) Less loss of nutrients:

[0046] Since the upper and lower surfaces of the material to be dried are heated at the same time in the present invention, and the dual refrigeration system evaporator dehumidifies, it has a very strong dehumidification capacity, so low-temperature drying can be fully achieved, and the effective ingredients and nutritional value of the material to be dried can be effectively retained;

[0047] (3) Energy saving:

[0048] In the present invention, on the one hand, the hot and humid air generated by the material to be dried is dehumidified and cooled by the evaporator, and then directly enters the condenser for heating and temperature increase, thereby achieving 100% heat recovery of the hot and humid air generated by the material to be dried; on the other hand, the drying system adopts a dual refrigeration system, and the condenser used for heating and the evaporator used for dehumidification share a fan, which not only reduces the number of fans, but also helps to save energy on the fans;

[0049] In addition, the drying system of the present invention has the characteristics of fast drying speed, consistent drying speed and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a schematic diagram of the working principle of the drying system of Example 1;

[0051] Figure 2 This is a position relationship diagram of the circulating fan, the condenser and the evaporator in the drying system of Example 1;

[0052] Figure 3 It is a schematic structural diagram of a condenser of a second refrigeration system of a drying system of Example 1;

[0053] Figure 4 It is a structural schematic diagram of the evaporators of the first refrigeration system and the second refrigeration system of the drying system of Example 1 (same frame);

[0054] Figure 5 It is a schematic diagram of the arrangement of the first refrigeration system condenser, evaporator and the second refrigeration system evaporator of the drying system of Example 1 (same frame);

[0055] Figure 6 It is a structural schematic diagram (independent frame) of a second arrangement of the evaporators of the first refrigeration system and the second refrigeration system of the drying system of Example 2;

[0056] Figure 7 A schematic diagram of a second arrangement of the first refrigeration system condenser, evaporator and the second refrigeration system evaporator of the drying system of Example 2 (independent frame);

[0057] Figure 8 It is a schematic diagram of a third arrangement of the first refrigeration system condenser, evaporator and the second refrigeration system evaporator of the drying system of Example 3;

[0058] In the figure, 10-a first refrigeration system, 101-a first refrigeration compressor, 102-a first condenser, 103-a first throttle valve, 104-a first evaporator, 105-a first gas-liquid separator, 106-a first high-pressure liquid storage tank, 20-a second refrigeration system, 201-a second refrigeration compressor, 202-a second condenser, 203-a second throttle valve, 204-a second evaporator, 205-a second gas-liquid separator, 206-a second high-pressure liquid storage tank, 30-a circulating fan, and 40-a wind distribution guide plate. DETAILED DESCRIPTION

[0059] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in conjunction with specific implementation methods.

[0060] Example 1

[0061] The superimposed double-circulation low-temperature drying system comprises: a first refrigeration system 10, a second refrigeration system 20, two groups of circulating fans 30, and an air distribution and guide plate 40; some intervals are left between the two groups of circulating fans 30;

[0062] The first refrigeration system 10 includes: a first gas-liquid separator 105, a first refrigeration compressor 101,

[0063] Two first condensers 102 and two first evaporators 104 are located on both sides of the two groups of circulating fans 30 and are symmetrically arranged from the inside to the outside;

[0064] The outlet of the first gas-liquid separator 105 is connected to the first refrigeration compressor 101, and the first refrigeration compressor 101 is divided into two branches, which lead to the first condenser 102 located on both sides of the two groups of circulation fans 30 respectively;

[0065] The first condenser 102 and the first evaporator 104 are connected via a pipeline; (the connection relationship between the two sets of first condensers 102 and the first evaporator 104 is the same)

[0066] The two pipes at the inlet of the first gas-liquid separator 105 are respectively connected to the two first evaporators 104 on both sides of the two groups of circulation fans 30;

[0067] The second refrigeration system 20 includes: a second gas-liquid separator 205, a second refrigeration compressor 201, two second condensers 202, and two second evaporators 204 located on both sides of the two groups of circulating fans 30; wherein the two second evaporators 204 are symmetrically arranged on both sides of the two groups of circulating fans 30;

[0068] The two second evaporators 204 are respectively located below or on either side of the two first evaporators 104.

[0069] The second evaporator 204 on one side is connected to the second condenser 202, and the second evaporator 204 on the other side is also connected to another second condenser 202. The pipelines of the two second condensers 202 are connected to the second refrigeration compressor 201 and the second gas-liquid separator 205 in sequence after being converged; the two pipelines at the inlet of the second gas-liquid separator 205 are respectively connected to the two second evaporators 204 on both sides of the circulation fan 30;

[0070] The first condenser 102, the first evaporator 104, the circulating fan 30, and the second condenser 202 are surrounded by a protective structure to form a drying chamber 50; an air distribution and guide plate 40 is provided between the circulating fan 30 and the second condenser 202, and both ends of the air distribution and guide plate 40 are connected to both sides of the protective structure. The air distribution and guide plate 40 is located in the drying chamber and has porous plates on both sides and sealing plates without holes at both ends.

[0071] A first throttle valve 103 is provided on the pipeline between the first evaporator 104 and the first condenser 102 ; a first high-pressure liquid storage tank 106 is provided on the pipeline between the first condenser 102 and the first evaporator 104 .

[0072] A second throttle valve 203 is respectively provided on the pipeline between the second evaporator 204 and the second condenser 202 ; a second high-pressure liquid storage tank 206 is respectively provided on the pipeline between the second evaporator 204 and the second condenser 202 .

[0073] In the above system, the first condenser 102 is a finned condenser;

[0074] The second condenser 202 is two sets of shelf-type heat exchangers; the second condenser 202 is two sets of plate-type freezers, and the second condenser 202 is located on both sides of the air outlet of the circulation fan 30;

[0075] The first evaporator 104 is a finned evaporator; the second evaporator 204 is a finned evaporator; the first evaporator 104 is located above the second evaporator 204 and the first evaporator 104 is located on the supporting structure (ie, frame or frame structure) of the second evaporator 204 shared by the second evaporator 204 .

[0076] Attached Figure 1Schematic diagram of the structure of the system of the present invention; Figure 2 The figure does not show other structures of the drying chamber, and only focuses on the positional relationship between the air distribution and guide plate 40 and the drying chamber 50 and the circulating fan 30.

[0077] The present invention specifically illustrates the working principle of a superimposed double-circulation low-temperature drying system through the structure of the superimposed double-circulation low-temperature drying system in the above-mentioned embodiment 1:

[0078] First, the material to be dried is placed on the second condenser 202 (plate condenser) in the second refrigeration system 20, and then the door of the drying chamber enclosure structure is closed, and the first refrigeration system 10, the second refrigeration system 20 and the circulating fan 30 are started respectively. After the circulating fan 30 starts to run, the exhausted air passes over the upper surface of the material to be dried and the lower surface of the second condenser 202 of the second refrigeration system 20, and the superheated refrigerant gas discharged from the second refrigeration compressor 201 of the second refrigeration system 20 enters the second condenser 202 of the second refrigeration system 20. At this time, the high-pressure superheated refrigerant gas discharged from the second refrigeration compressor 201 passes through the second condenser 202, transferring heat to the material to be dried. The material increases the temperature of the lower part of the material to be dried, and the high-pressure superheated refrigerant gas itself condenses into a high-pressure liquid, which enters the high-pressure liquid storage tank through the high-pressure refrigeration pipeline. The high-pressure refrigerant liquid coming out of the high-pressure liquid storage tank is throttled and depressurized by the second throttle valve 203 to become a low-pressure refrigerant liquid, and enters the second evaporator 204 of the second refrigeration system 20. After the air blown out by the absorption fan passes through the hot and humid air on the upper surface of the material to be dried and the lower surface of the flat plate condenser of the second refrigeration system 20, the low-pressure refrigerant liquid evaporates into a low-pressure refrigerant gas. After the temperature and humidity of the hot and humid air are reduced, it becomes low-temperature and low-humidity air, which passes through the first condenser 102 (finned condenser) of the first refrigeration system 10.

[0079] Since the first refrigeration system 10 is also started, the low-temperature and low-humidity air absorbs the heat of the superheated refrigerant gas discharged by the first refrigeration compressor 101 of the first refrigeration system, the temperature of the low-temperature and low-humidity air increases, the relative humidity decreases, and is sucked into the circulation fan 30, and continues to pass over the upper surface of the material to be dried and the lower surface of the second condenser 202 of the second refrigeration system 20. The refrigerant of the first refrigeration system 10 transfers heat to the low-temperature and low-humidity air in the first condenser 102, and then becomes a high-pressure refrigerant liquid, enters the high-pressure liquid storage tank of the first refrigeration system 10, passes through the second throttle valve 203 of the second refrigeration system 20 to reduce the pressure and become a low-pressure refrigerant liquid, and enters the first evaporator 104 of the first refrigeration system 10. After the low-pressure refrigerant liquid absorbs the hot and humid air blown out by the fan and passes over the upper surface of the material to be dried and the lower surface of the second condenser 202 of the second refrigeration system 20, the low-pressure refrigerant liquid evaporates into a low-pressure refrigerant The hot and humid air turns into low-temperature and low-humidity air after the temperature and humidity are reduced, and is also heated by the first condenser 102 of the first refrigeration system 10. The low-temperature and low-humidity air absorbs the heat of the superheated refrigerant gas discharged by the first refrigeration compressor 101 of the first refrigeration system 10, and the temperature of the low-temperature and low-humidity air increases, and the relative humidity decreases. Driven by the fan, the low-temperature and low-humidity air continues to pass over the upper surface of the material to be dried and the lower surface of the second condenser 202 of the second refrigeration system 20, and the cycle continues in this way. The material to be dried is continuously heated by the low-temperature, hot and humid air blown out by the fan and the heat of the second condenser 202 of the second refrigeration system 20, and its moisture is continuously evaporated into hot and humid water vapor; in addition, under the action of the air distribution and guide plates 40, the wind speeds of the two groups of circulating fans 30 are stable, the air volume passing over the dried material is uniform, and the drying effect is consistent. Then, the air passes through the evaporators of the first independent refrigeration system and the second independent refrigeration system to condense and precipitate, thereby achieving the purpose of drying the dried material.

[0080] like Figure 2 As shown, the first condenser 102 of the first refrigeration system 10, the first evaporator 104 and the second evaporator 204 of the second refrigeration system 20 are divided into two parts according to their heat exchange amounts and placed on both sides of the air intake of the circulation fan 30, which can effectively increase the single drying amount and facilitate the loading and unloading of goods.

[0081] In summary, the stacked double-circulation low-temperature drying system provided by the present invention has the following significant advantages when applied to drying materials such as Chinese herbal medicines, aquatic products, fruits and vegetables:

[0082] First, the materials to be dried are highly safe and free of mildew:

[0083] Due to the use of the drying system with heating and dehumidification functions in the present invention, the drying process is not affected by the environmental climate, reducing the problem of corruption and deterioration caused by bacteria growth due to the influence of climate in other drying methods, and improving the safety of the material to be dried;

[0084] Second, the nutritional value is high. Since the upper and lower surfaces of the material to be dried are heated at the same time, and the dual refrigeration system evaporator dehumidifies, it has a strong dehumidification capacity, so low-temperature drying can be achieved, avoiding the loss of nutrients caused by high temperature in the material to be dried, and effectively retaining the effective ingredients and nutritional value of the material to be dried;

[0085] Third, low energy consumption. On the one hand, during the drying process, the hot and humid air generated by the material to be dried is dehumidified and cooled by the evaporator, and then directly enters the condenser for heating and temperature increase, thus achieving 100% heat recovery of the hot and humid air generated by the material to be dried. On the other hand, the drying system adopts a dual refrigeration system, and the condenser used for heating and the evaporator used for dehumidification share a fan, which not only reduces the number of fans, but also helps to save energy.

[0086] Fifth, the drying speed is fast. During the drying process of the material to be dried, the upper and lower parts are heated at the same time, which is conducive to the evaporation of moisture in the material to be dried and the drying speed is fast.

[0087] Sixth, the drying speed is consistent; the material to be dried is heated at the same time from top to bottom, and each point is heated evenly, ensuring that the drying speed of the material to be dried is consistent;

[0088] Seventh, environmental protection; during the operation of the system, a completely closed cycle is adopted, and no harmful gases are discharged into the ambient atmosphere, so it is very environmentally friendly.

[0089] The above advantages are precisely what traditional drying methods such as air drying, natural drying, gas drying, electric heating drying, heat pump drying, and vacuum freeze drying do not have. The drying system of the present invention overcomes the defects of the above drying methods and has significant progress.

[0090] Example 2

[0091] The difference from Example 1 is that the first evaporator 104 is located above the second evaporator 204 and the first evaporator 104 is located on the supporting structure (ie, frame or frame structure) of the second evaporator 204 ; the rest of the structure is the same as Example 1.

[0092] Example 3

[0093] The difference from Example 1 is that, alternatively, the first evaporator 104 is arranged in parallel with the second evaporator 204 , the first evaporator 104 is located outside the second evaporator 204 , and respective supporting structures (ie, frames or frame structures) are arranged below the first evaporator 104 and the second evaporator 204 .

[0094] Although the preferred specific embodiments of the present invention have been described above by way of example, the protection scope of the present invention is not limited to the above description, but is defined by all technical features and their equivalent technical features given in the attached claims. It can be understood by those skilled in the art that any modification and variation may still fall within the protection scope of the claims of the present invention without departing from the essence and spirit taught by the present invention.

[0095] For example, the circulating fans can be set to two groups or to one group according to specific needs; for example, the second condenser can also be set to only one group. Similar changes also fall within the protection scope of the present invention.

Claims

1. Superimposed double-circulation low-temperature drying system, characterized in that: The drying system comprises: a first refrigeration system (10), a second refrigeration system (20), a circulating fan (30), and an air distribution and guide plate (40); The first refrigeration system (10) comprises: a first gas-liquid separator (105), a first refrigeration compressor (101), two first condensers (102) located on both sides of the circulation fan (30), and two first evaporators (104); The outlet of the first gas-liquid separator (105) is connected to the first refrigeration compressor (101), and the first refrigeration compressor (101) is divided into two branches, which respectively lead to the first condenser (102) located on both sides of the circulation fan (30); The first condenser (102) and the first evaporator (104) are connected via a pipeline; Two pipelines at the inlet of the first gas-liquid separator (105) are respectively connected to the two first evaporators (104) on both sides of the circulation fan (30); A first throttle valve (103) is provided on the pipeline between the first evaporator (104) and the first condenser (102); a first high-pressure liquid storage tank (106) is provided on the pipeline between the first condenser (102) and the first evaporator (104); The second refrigeration system (20) comprises: a second gas-liquid separator (205), a second refrigeration compressor (201), two second condensers (202), and two second evaporators (204) located on both sides of the circulation fan (30); The two second evaporators (204) are respectively located below or on either side of the two first evaporators (104). The second evaporator (204) on one side is connected to the second condenser (202), and the second evaporator (204) on the other side is also connected to another second condenser (202); the pipelines of the two second condensers (202) are converged and connected to the second refrigeration compressor (201) and the second gas-liquid separator (205) in sequence; the two pipelines at the inlet of the second gas-liquid separator (205) are respectively connected to the two second evaporators (204) on both sides of the circulation fan (30); A second throttle valve (203) is respectively provided on the pipeline between the second evaporator (204) and the second condenser (202); a second high-pressure liquid storage tank (206) is respectively provided on the pipeline between the second evaporator (204) and the second condenser (202); The first condenser (102), the first evaporator (104), the circulating fan (30), and the second condenser (202) are surrounded by a protective structure to form a drying chamber (50); an air distribution and guide plate (40) is provided between the circulating fan (30) and the second condenser (202), and two ends of the air distribution and guide plate (40) are connected to two sides of the protective structure; The method for using the superimposed double-circulation low-temperature drying system comprises the following steps: S1: opening the enclosure door of the drying chamber (50), placing the material to be dried above the second condenser (202), and then closing the enclosure door of the drying chamber (50); S2: respectively starting the first refrigeration system (10), the second refrigeration system (20) and the circulating fan (30), the circulating fan (30) starts to operate, the air discharged by the circulating fan (30) passes over the upper surface of the material to be dried and the lower surface of the second condenser (202), the superheated refrigerant gas discharged by the second refrigeration compressor (201) enters the second condenser (202), and the high-pressure superheated refrigerant gas discharged by the second refrigeration compressor (201) passes through the second condenser (202) and transfers heat to the material to be dried, thereby increasing the temperature of the lower part of the material to be dried; S3: The high-pressure superheated refrigerant gas condenses into high-pressure liquid and enters the second high-pressure liquid storage tank (206) through the high-pressure refrigeration pipeline. The high-pressure refrigerant liquid coming out of the second high-pressure liquid storage tank (206) is throttled and reduced in pressure by the second throttle valve (203) to become low-pressure refrigerant liquid and enters the second evaporator (204). After the air blown out by the circulation fan (30) passes over the hot and humid air on the upper surface of the material to be dried and the lower surface of the second condenser (202), the low-pressure refrigerant liquid evaporates into low-pressure refrigerant gas. After the temperature and humidity of the hot and humid air decrease, it becomes low-temperature and low-humidity air and passes through the first condenser (102). Since the first refrigeration system (10) is also started, the low-temperature and low-humidity air absorbs the heat of the superheated refrigerant gas discharged by the first refrigeration compressor (101). The temperature of the low-temperature and low-humidity air increases and the relative humidity decreases. The low-temperature and low-humidity air is sucked into the circulation fan (30) and continues to pass over the upper surface of the material to be dried and the second condenser (202). ), and the refrigerant in the second condenser (202) transfers heat to the low-temperature and low-humidity air in the first condenser (102), and then becomes a high-pressure refrigerant liquid, enters the first high-pressure liquid storage tank (106), passes through the first throttle valve (103) to reduce the pressure and become a low-pressure refrigerant liquid, and enters the first evaporator (104). The low-pressure refrigerant liquid absorbs the hot and humid air blown by the circulating fan (30) and passes over the upper surface of the material to be dried and the lower surface of the circulating fan (30). The low-pressure refrigerant liquid evaporates into a low-pressure refrigerant gas. The hot and humid air is reduced in temperature and humidity and becomes low-temperature and low-humidity air. It is also heated by the first condenser (102). The low-temperature and low-humidity air absorbs the heat of the superheated refrigerant gas discharged by the first refrigeration compressor (101). The temperature of the low-temperature and low-humidity air increases, and the relative humidity decreases. Driven by the circulating fan (30), the low-temperature and low-humidity air continues to pass over the upper surface of the material to be dried and the lower surface of the second condenser (202); S4: Steps S2 and S3 are continuously repeated in this way, and the material to be dried is continuously heated by the low-temperature, moist hot air blown out by the fan and the heat of the second condenser (202), and its moisture is continuously evaporated into hot and moist water vapor, thereby drying the material to be dried.

2. The superimposed double-circulation low-temperature drying system according to claim 1 is characterized in that: Two first condensers (102) and two first evaporators (104) are symmetrically arranged on both sides of the circulation fan (30) from the inside to the outside.

3. The superimposed double-circulation low-temperature drying system according to claim 1 is characterized in that: Two second evaporators (204) are symmetrically arranged on both sides of the circulation fan (30), and the second evaporators (204) are respectively located below the two first evaporators (104).

4. The superimposed double-circulation low-temperature drying system according to claim 1 is characterized in that: The two sides of the air distribution and guide plate (40) are porous plates, and the two ends are sealing plates without holes.

5. The superimposed double-circulation low-temperature drying system according to claim 1 is characterized in that: The first condenser (102) is a finned condenser; The second condenser (202) is two sets of shelf-type heat exchangers; The first evaporator (104) is a fin-type evaporator; The second evaporator (204) is a fin-type evaporator; The second condenser (202) is two sets of flat-plate freezers, and the second condenser (202) is located on both sides of the air outlet of the circulation fan (30); Two circulation fans (30) are arranged in the drying chamber (50).

6. The superimposed double-circulation low-temperature drying system according to claim 1, characterized in that: The first evaporator (104) is located above the second evaporator (204), and the first evaporator (104) is located on a support structure shared by the second evaporator (204) and located on the second evaporator (204); Alternatively, the first evaporator (104) is located above the second evaporator (204), and the first evaporator (104) and the second evaporator (204) have a support structure of the first evaporator (104); and a corresponding support structure is provided below the second evaporator (204); Alternatively, the first evaporator (104) is arranged in parallel with the second evaporator (204), and the first evaporator (104) is located outside the second evaporator (204).

7. Application of the superimposed double-circulation low-temperature drying system according to claim 1 in drying Chinese herbal medicines, aquatic products, fruits and vegetables.

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