Freeze dryer and control method thereof

Abstract

The present invention relates to a refrigerated dryer and a control method thereof, the refrigerated dryer comprising: a refrigeration compressor; a first heat exchanger and a second heat exchanger, both comprising a refrigerant inlet and a refrigerant outlet, the refrigeration compressor, the first heat exchanger and the second heat exchanger being interconnected through a pipeline; a control valve, arranged on the pipeline, so that the refrigeration compressor, the second heat exchanger and the first heat exchanger form a first refrigerant circulation loop or the refrigeration compressor, the first heat exchanger and the second heat exchanger form a second refrigerant circulation loop, and realize alternating heat exchange between the first heat exchanger and the second heat exchanger. The present invention can make the refrigerated dryer work and operate in a high-performance range for a long time through alternating heat exchange of two heat exchangers, improve the performance of the refrigerated dryer and avoid failure of the refrigerated dryer.

Description

Technical Field

[0001] The present invention relates to the technical field of dryers, and in particular to a refrigerated dryer and a control method thereof. Background Art

[0002] Traditional refrigerated dryers need to control the evaporation temperature above 0°C (the freezing point of water) with the help of a bypass valve to prevent the condensed water in the compressed air from freezing, thus reducing the performance of the dryer. In the prior art, the pressure drop of compressed air will increase when it passes through the dryer, and in severe cases, the air side channel will be completely blocked. The heat exchanger body may also swell and crack due to ice, causing the dryer to fail. Summary of the invention

[0003] In view of the above-mentioned problems existing in the prior art, the object of the present invention is to provide a refrigerated dryer and a control method thereof, which can utilize another heat exchanger for heat exchange when one heat exchanger needs to be defrosted, and avoid failure of the refrigerated dryer while improving the performance of the refrigerated dryer through the alternating heat exchange of the two heat exchangers.

[0004] In order to achieve the above object, the present invention provides a refrigerated dryer, comprising:

[0005] Refrigeration compressors;

[0006] The first heat exchanger and the second heat exchanger each include a refrigerant inlet and a refrigerant outlet, and the refrigeration compressor, the first heat exchanger and the second heat exchanger are interconnected through a pipeline;

[0007] A control valve is arranged on the pipeline to connect the refrigeration compressor, the second heat exchanger, and the first heat exchanger in sequence to form a first refrigerant circulation loop, or to connect the refrigeration compressor, the first heat exchanger, and the second heat exchanger in sequence to form a second refrigerant circulation loop, thereby realizing alternating heat exchange between the first heat exchanger and the second heat exchanger.

[0008] In some embodiments, the control valve comprises:

[0009] A first reversing valve is provided on a first connecting pipeline between the refrigerant inlet of the first heat exchanger and the second heat exchanger and the outlet of the refrigeration compressor;

[0010] a second reversing valve, provided on a second connecting pipeline between the refrigerant outlets of the first heat exchanger and the second heat exchanger and the inlet of the refrigeration compressor, and the first connecting pipeline and the second connecting pipeline are in communication;

[0011] The flow direction of the refrigerant can be switched by adjusting the first reversing valve and the second reversing valve to form the first refrigerant circulation circuit or the second refrigerant circulation circuit.

[0012] In some embodiments, the first reversing valve and the second reversing valve are four-way reversing valves;

[0013] The first connecting pipeline includes a first pipeline provided between the outlet of the refrigeration compressor and the first inlet of the first reversing valve, a second pipeline provided between the first outlet of the first reversing valve and the refrigerant inlet of the first heat exchanger, and a third pipeline provided between the second outlet of the first reversing valve and the refrigerant inlet of the second heat exchanger, and the first pipeline and the second pipeline can be connected or the first pipeline and the third pipeline can be connected by switching the first reversing valve;

[0014] The second connecting pipeline includes a fourth pipeline provided between the refrigerant outlet of the first heat exchanger and the first inlet of the second reversing valve, a fifth pipeline provided between the refrigerant outlet of the second heat exchanger and the second inlet of the second reversing valve, and a sixth pipeline provided between the first outlet of the second reversing valve and the inlet of the refrigeration compressor, and the fourth pipeline and the sixth pipeline can be connected or the fifth pipeline and the sixth pipeline can be connected by switching the second reversing valve;

[0015] The second inlet of the first reversing valve is connected to the second outlet of the second reversing valve via a third connecting pipeline.

[0016] In some embodiments, the refrigerated dryer also includes a condenser, a drying filter and a throttling device connected in sequence through pipelines, the inlet of the condenser is connected to the refrigerant outlet of the first heat exchanger or the second heat exchanger, and the outlet of the throttling device is connected to the refrigerant inlet of the second heat exchanger or the first heat exchanger.

[0017] In some embodiments, the refrigerated dryer further includes a gas-liquid separator disposed between a refrigerant outlet of the first heat exchanger or the second heat exchanger and an inlet of the refrigeration compressor.

[0018] In some embodiments, the first heat exchanger and the second heat exchanger further include a gas inlet and a gas outlet, respectively, and external compressed air enters the first heat exchanger or the second heat exchanger through the gas inlet for heat exchange and flows out from the gas outlet;

[0019] The gas inlets of the first heat exchanger and the second heat exchanger are respectively connected to compressed air inlet pipelines, and the gas outlets of the first heat exchanger and the second heat exchanger are respectively connected to compressed air outlet pipelines.

[0020] In some embodiments, the compressed air inlet pipeline includes a compressed air inlet main pipe, and compressed air inlet branches connected to the compressed air inlet main pipe and respectively connected to the gas inlets of the first heat exchanger and the second heat exchanger; the compressed air outlet pipeline includes compressed air outlet branches respectively connected to the gas outlets of the first heat exchanger and the second heat exchanger, and a compressed air outlet main pipe respectively connected to the compressed air outlet branches.

[0021] In some embodiments, the compressed air inlet branch pipe and the compressed air outlet branch pipe are provided with gas regulating valves.

[0022] In some embodiments, a first pressure sensor is provided on the compressed air intake manifold, and a second pressure sensor is provided on the compressed air exhaust manifold.

[0023] In some embodiments, both the first reversing valve and the second reversing valve are solenoid valves.

[0024] The present invention also provides a control method for the above-mentioned refrigerated dryer, the method comprising:

[0025] Obtaining the gas inlet pressure and the gas outlet pressure of the gas inlet of the refrigerated dryer;

[0026] Calculating the pressure difference between the inlet pressure and the outlet pressure according to the inlet pressure and the outlet pressure;

[0027] comparing the pressure difference with a preset pressure threshold;

[0028] Based on the comparison result, the first refrigerant circulation circuit and the second refrigerant circulation circuit are controlled to switch between an on state and an off state.

[0029] In some embodiments, when the first refrigerant circulation circuit is turned on and the second refrigerant circulation circuit is turned off, the method specifically includes:

[0030] Obtaining a first gas inlet pressure of a gas inlet and a first gas outlet pressure of a gas outlet of the first heat exchanger;

[0031] Calculating a first pressure difference between the first inlet pressure and the first outlet pressure according to the first inlet pressure and the first outlet pressure;

[0032] comparing the first pressure difference with a preset pressure threshold;

[0033] If the first pressure difference is greater than the preset pressure threshold, the first refrigerant circulation circuit is controlled to be disconnected and the second refrigerant circulation circuit is controlled to be connected; if the first pressure difference is less than or equal to the preset pressure threshold, the first refrigerant circulation circuit is controlled to be connected and the second refrigerant circulation circuit is disconnected.

[0034] In some embodiments, when the second refrigerant circulation circuit is turned on and the first refrigerant circulation circuit is turned off, the method specifically includes:

[0035] Obtaining a second gas inlet pressure of a gas inlet and a second gas outlet pressure of a gas outlet of the second heat exchanger;

[0036] Calculating a second pressure difference between the second inlet pressure and the second outlet pressure according to the second inlet pressure and the second outlet pressure;

[0037] comparing the second pressure difference with a preset pressure threshold;

[0038] If the second pressure difference is greater than the preset pressure threshold, the second refrigerant circulation circuit is controlled to be disconnected and the first refrigerant circulation circuit is connected; if the second pressure difference is less than or equal to the preset pressure threshold, the second refrigerant circulation circuit is controlled to be connected and the first refrigerant circulation circuit is disconnected.

[0039] Compared with the prior art, the refrigerated dryer and the control method thereof provided in the embodiment of the present invention are provided with two heat exchangers interconnected with the refrigeration compressor, and control valves are provided on the corresponding refrigerant inlet and outlet pipelines. Different refrigerant circulation loops can be formed by adjusting the control valves, so that when the air side channel of one of the heat exchangers is blocked or the heat exchanger cannot work normally due to ice formation, the heat exchanger that cannot work normally is de-iced (defrosted), and switched to another heat exchanger for heat exchange work, so as to ensure the normal heat exchange work of the refrigerated dryer, improve the performance of the refrigerated dryer and avoid failure of the refrigerated dryer. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In the drawings, which are not necessarily drawn to scale, the same reference numerals may describe similar parts in different views. The same reference numerals with letter suffixes or different letter suffixes may represent different instances of similar parts. The accompanying drawings generally illustrate various embodiments by way of example and not limitation, and together with the specification and claims, are used to illustrate the embodiments of the invention. When appropriate, the same reference numerals are used throughout the drawings to refer to the same or similar parts. Such embodiments are illustrative and are not intended to be exhaustive or exclusive embodiments of the present device.

[0041] Figure 1 It is a structural schematic diagram of a refrigerated dryer in a first working state according to an embodiment of the present invention;

[0042] Figure 2 It is a structural schematic diagram of a refrigerated dryer in a second working state according to an embodiment of the present invention;

[0043] Figure 3 A control flow chart of a control method for a refrigerated dryer according to an embodiment of the present invention;

[0044] Figure 4 Another control flow chart of the control method of the refrigerated dryer according to the embodiment of the present invention;

[0045] Figure 5 This is another control flow chart of the control method of the refrigerated dryer according to an embodiment of the present invention.

[0046] Reference numerals:

[0047] 1-refrigeration compressor; 21-first heat exchanger, 22-second heat exchanger; 31-first reversing valve, 32-second reversing valve; 4-condenser; 5-drying filter; 6-throttling device; 7-gas-liquid separator; 81-first gas regulating valve, 82-first gas regulating valve, 83-third gas regulating valve, 84-fourth gas regulating valve; 91-first pressure sensor, 92-second pressure sensor;

[0048] 101 - first pipeline, 102 - second pipeline, 103 - third pipeline; 201 - fourth pipeline, 202 - fifth pipeline, 203 - sixth pipeline; 301 - third connecting pipeline; 4011 - compressed air intake main pipe, 4012 - compressed air intake branch pipe; 4021 - compressed air outlet branch pipe, 4022 - compressed air outlet main pipe. DETAILED DESCRIPTION

[0049] In order to make the purpose, technical solution and advantages of the embodiment of the present invention more clear, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiment of the present invention.

[0050] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0051] In order to keep the following description of the embodiments of the present invention clear and concise, detailed descriptions of well-known functions and well-known components are omitted.

[0052] Figure 1 and Figure 2 The schematic diagram of the structure of the refrigerated dryer according to the embodiment of the present invention is shown in the figure (the direction of the arrow in the figure indicates the direction of fluid flow). Figure 1 and Figure 2 As shown, an embodiment of the present invention provides a refrigerated dryer (hereinafter referred to as a refrigerated dryer), comprising:

[0053] Refrigeration compressor 1;

[0054] The first heat exchanger 21 and the second heat exchanger 22 each include a refrigerant inlet and a refrigerant outlet, and the refrigeration compressor 1, the first heat exchanger 21 and the second heat exchanger 22 are connected to each other through a pipeline;

[0055] The control valve is arranged on the pipeline so that the refrigeration compressor 1, the second heat exchanger 22, and the first heat exchanger 21 are connected in sequence to form a first refrigerant circulation loop or the refrigeration compressor 1, the first heat exchanger 21, and the second heat exchanger 22 are connected in sequence to form a second refrigerant circulation loop, so as to realize the alternating heat exchange between the first heat exchanger 21 and the second heat exchanger 22. The refrigeration dryer provided in the embodiment of the present invention is provided with two heat exchangers interconnected with the refrigeration compressor 1, and a control valve is arranged on the corresponding refrigerant inlet and outlet pipelines. Different refrigerant circulation loops can be formed by adjusting the control valve, so that when the air side channel of one of the heat exchangers is blocked or the heat exchanger cannot work normally due to ice formation of the heat exchanger, the heat exchanger that cannot work normally is de-iced (defrosted), and switched to another heat exchanger for heat exchange work, so as to ensure the normal heat exchange work of the refrigeration dryer, improve the performance of the refrigeration dryer and avoid failure of the refrigeration dryer.

[0056] In some embodiments, Figure 1 and Figure 2 As shown, the control valve comprises:

[0057] The first reversing valve 31 is provided on the first connecting pipeline between the refrigerant inlet of the first heat exchanger 21 and the second heat exchanger 22 and the outlet of the refrigeration compressor 1;

[0058] The second reversing valve 32 is provided on the second connecting pipeline between the refrigerant outlets of the first heat exchanger 21 and the second heat exchanger 22 and the inlet of the refrigeration compressor 1, and the first connecting pipeline is in communication with the second connecting pipeline;

[0059] The flow direction of the refrigerant can be switched by adjusting the first reversing valve 31 and the second reversing valve 32 to form the first refrigerant circulation circuit or the second refrigerant circulation circuit.

[0060] In this embodiment, a first reversing valve 31 is provided on the connecting pipeline between the refrigerant inlet of the first heat exchanger 21 and the second heat exchanger 22 and the outlet of the refrigeration compressor 1, and a second reversing valve 32 is provided on the connecting pipeline between the refrigerant outlet of the first heat exchanger 21 and the second heat exchanger 22 and the inlet of the refrigeration compressor 1, and the first reversing valve 31 and the second reversing valve are connected. By reversing the reversing valve, the refrigerant flow direction can be switched, and the switching is convenient and fast.

[0061] In other embodiments, the inlets and outlets of the refrigeration compressor 1, the first heat exchanger 21, and the second heat exchanger 22 can be connected respectively by different pipelines, and corresponding one-way valves or stop valves can be arranged on the corresponding pipelines to open or close the corresponding pipelines, thereby realizing the alternating operation of the first refrigerant circulation loop and the second refrigerant circulation loop.

[0062] Further, in a preferred embodiment, if Figure 1 and Figure 2 As shown, the first reversing valve 31 and the second reversing valve 32 are both four-way reversing valves;

[0063] The first connecting pipeline includes a first pipeline 101 (compressor outlet main pipe) provided between the outlet of the refrigeration compressor 1 and the first inlet (A) of the first reversing valve 31, a second pipeline 102 provided between the first outlet (B) of the first reversing valve 31 and the refrigerant inlet of the first heat exchanger 21, and a third pipeline 103 provided between the second outlet (C) of the first reversing valve 31 and the refrigerant inlet of the second heat exchanger 22. By switching the first reversing valve 31, the first pipeline 101 and the second pipeline 102 can be connected or the first pipeline 101 and the third pipeline 103 can be connected;

[0064] The second connecting pipeline includes a fourth pipeline 201 provided between the refrigerant outlet of the first heat exchanger 21 and the first inlet (E) of the second reversing valve 32, a fifth pipeline 202 provided between the refrigerant outlet of the second heat exchanger 22 and the second inlet (F) of the second reversing valve 32, and a sixth pipeline 203 (compressor inlet manifold) provided between the first outlet (G) of the second reversing valve 32 and the inlet of the refrigeration compressor 1. By switching the second reversing valve 32, the fourth pipeline 201 and the sixth pipeline 203 can be connected or the fifth pipeline 202 and the sixth pipeline 203 can be connected;

[0065] The second inlet (D) of the first reversing valve 31 and the second outlet (H) of the second reversing valve 32 are connected via a third connecting pipeline 301 .

[0066] In this embodiment, a four-way reversing valve is used to adjust the flow direction of the fluid, which can reduce the pipeline structure and make the layout of various components and pipelines of the refrigerated dryer more reasonable and compact.

[0067] In some other embodiments, the first reversing valve 31 and the second reversing valve 32 may also be three-way valves. For example, the first reversing valve 31 may not be provided with a second inlet, and the second reversing valve 32 may not be provided with a second outlet. The fifth pipeline 202 and the second pipeline 102 may be connected through a fourth connecting pipeline, so that the refrigerant flowing out of the second heat exchanger 22 flows into the first heat exchanger 21; the fourth pipeline 201 and the third pipeline 102 may also be connected through a fifth connecting pipeline, so that the refrigerant flowing out of the first heat exchanger 21 flows into the second heat exchanger 22. The specific structure of the reversing valve and the arrangement of the corresponding pipelines and components are not specifically limited in this embodiment. For example, when the processing capacity of the two heat exchangers is greatly different, pipelines can be set separately and corresponding control valves can be set.

[0068] In this embodiment, the first reversing valve 41 and the second reversing valve 42 are preferably solenoid valves. The flow direction of the fluid in the reversing valve can be switched by turning the solenoid valve on and off, which is convenient to control and the solenoid valve is sensitive to response.

[0069] In some embodiments, the refrigerated dryer further comprises a condenser 4, a drying filter 5 and a throttling device 6 which are sequentially connected by pipelines. The inlet of the condenser 4 is connected to the refrigerant outlet of the first heat exchanger 21 or the second heat exchanger 22, and the outlet of the throttling device 6 is connected to the refrigerant inlet of the second heat exchanger 22 or the first heat exchanger 21, so that the medium-temperature gaseous (or gas-liquid mixed) refrigerant formed in the heat exchanger after the deicing operation enters the condenser 4 for condensation to form a medium-temperature and high-pressure pure liquid refrigerant. After a part of the impurities are filtered out by the drying filter 5, the refrigerant enters the throttling device 6 for throttling to form a low-temperature and low-pressure gas-liquid mixed refrigerant, and then enters the other heat exchanger to work.

[0070] In this embodiment, the condenser 4, the drying filter 5 and the throttling device 6 connected in sequence are arranged between the second outlet (H) of the second reversing valve 32 and the second inlet (D) of the first reversing valve 31 and are connected through the third connecting pipe 301.

[0071] In some embodiments, the refrigerated dryer further includes a gas-liquid separator 7 disposed between the refrigerant outlet of the first heat exchanger 21 or the second heat exchanger 22 and the inlet of the refrigeration compressor 1 .

[0072] In this embodiment, since the refrigerant outlets of the first heat exchanger 21 and the second heat exchanger 22 are respectively connected to the inlet of the second reversing valve, the gas-liquid separator 7 is arranged between the second outlet of the second reversing valve 32 and the inlet of the refrigeration compressor 1, that is, the refrigerant inlet of the gas-liquid separator 7 is connected to the second outlet of the second reversing valve 32, and the refrigerant outlet of the gas-liquid separator 7 is connected to the inlet of the refrigeration compressor 1. The gas-liquid separator 7 can separate a small amount of liquid refrigerant contained in the low-temperature and low-pressure gaseous refrigerant flowing out of the first heat exchanger 21 or the second heat exchanger 22 after heat exchange, so as to prevent the liquid refrigerant from flowing into the refrigeration compressor 1 and causing damage to the refrigeration compressor 1.

[0073] The first heat exchanger 21 and the second heat exchanger 22 further include a gas inlet and a gas outlet, respectively. External high-temperature and high-pressure compressed air enters the first heat exchanger 21 or the second heat exchanger 22 through the gas inlet, exchanges heat with the low-temperature and low-pressure gas-liquid mixed refrigerant entering the first heat exchanger 21 or the second heat exchanger 22 from the refrigerant inlet, and processes the compressed air. The compressed air after heat exchange flows out from the gas outlet.

[0074] Furthermore, the gas inlets of the first heat exchanger 21 and the second heat exchanger 22 are connected to compressed air intake pipelines, and the gas outlets of the first heat exchanger 21 and the second heat exchanger 22 are connected to compressed air intake pipelines to realize the entry and exit of compressed air in each heat exchanger.

[0075] In this embodiment, the compressed air intake pipeline includes a compressed air intake main pipe 4011 and a compressed air intake branch pipe 4012 connected to the compressed air intake main pipe 4011 and respectively connected to the second inlet of the first heat exchanger 21 and the second heat exchanger 22; the compressed air outlet pipeline includes a compressed air outlet branch pipe 4021 respectively connected to the second outlet of the first heat exchanger 21 and the second heat exchanger 22, and a compressed air outlet main pipe 4022 respectively connected to the compressed air outlet branch pipes 4021.

[0076] like Figure 1 and Figure 2 As shown, a gas regulating valve is provided on the compressed air inlet branch pipe 4012 and the compressed air outlet branch pipe 4021 to control the compressed air entering and leaving the heat exchanger. Figure 1As shown, when the first heat exchanger 21 is exchanging heat, the first gas regulating valve 81 on the compressed air inlet branch pipe 4012 connected to the gas inlet of the first heat exchanger 21 and the second gas regulating valve 82 on the compressed air outlet branch pipe 4021 connected to the gas outlet of the first heat exchanger 21 are controlled to be opened, so that the compressed air can enter and exit the first heat exchanger 21; at the same time, the third gas regulating valve 83 on the compressed air inlet branch pipe 4012 connected to the gas inlet of the second heat exchanger 22 and the fourth gas regulating valve 84 on the compressed air outlet branch pipe 4021 connected to the gas outlet of the second heat exchanger 22 are controlled to be closed. Similarly, as Figure 2 As shown, when the second heat exchanger 22 performs heat exchange, the third gas regulating valve 83 and the fourth gas regulating valve 84 are controlled to be opened, and the first gas regulating valve 81 and the second gas regulating valve 82 are controlled to be closed. Further, a first pressure sensor 91 is provided on the compressed air intake manifold 4011, and a second pressure sensor 92 is provided on the compressed air exhaust manifold 4022 to respectively detect the pressure of the compressed air inlet and outlet, and then judge whether the heat exchanger needs to be de-iced (whether it needs to be switched to another heat exchanger for heat exchange) according to the pressure difference between the inlet and outlet pressures. For example, after detecting that the pressure drop of the compressed air inlet and outlet (the pressure drop caused by energy loss when the compressed air flows in the gas pipeline) reaches a preset value, it can be determined that the heat exchanger connected to the inlet and outlet of the compressed air may be frozen or the ice reaches a certain degree, which will cause the performance of the cold dryer to be reduced, and may even cause the air side channel to be completely blocked.

[0077] In this embodiment, since the first heat exchanger 21 and the second heat exchanger 22 work alternately, it is sufficient to set a pressure sensor on the compressed air intake main pipe 4011 and the compressed air exhaust main pipe 4022. In a specific implementation, a pressure sensor can also be set on each compressed air intake branch pipe 4012 and the compressed air outlet branch pipe 4021, which is not specifically limited in this embodiment.

[0078] The specific working process of the refrigerated dryer provided by the embodiment of the present invention is as follows:

[0079] Specifically, the first heat exchanger 21 and the second heat exchanger 22 have two working states, namely, a deicing state and a heat exchange state. The heat exchange state is the normal working state of the heat exchanger, and the deicing state is the state in which the heat exchanger performs deicing after ice may form or ice reaches a certain degree after a certain period of heat exchange. Figure 1As shown, when the second heat exchanger 22 is frozen, the compressed air is stopped from being passed into the second heat exchanger 22, and compressed air is passed into the first heat exchanger 21 to enable the first heat exchanger 21 to perform heat exchange work. At this time, the first heat exchanger 21 is in a normal working heat exchange state, and the second heat exchanger 22 is in a deicing state: the first pipeline 101 is connected to the third pipeline 103, the fifth pipeline 202 is connected to the third connecting pipeline 301, the third connecting pipeline 301 is connected to the second pipeline 102, and the fourth pipeline 201 is connected to the sixth pipeline 203. The refrigerant is compressed by the refrigeration compressor 1 to become a high-temperature and high-pressure gaseous refrigerant, and enters the second heat exchanger 22 through the first pipeline 101, the first reversing valve 31, and the third pipeline 103 to de-ice the second heat exchanger 22. The de-iced refrigerant releases a certain amount of heat to become a medium-temperature gaseous (or gas-liquid mixed) refrigerant, which flows out through the fifth pipeline 202, and enters the condenser 4 through the second reversing valve 32 and the third connecting pipeline 301 for condensation, and is filtered out of impurities through the drying filter 5. The filtered refrigerant enters the throttling device 6 for throttling and cooling to form a low-temperature and low-pressure gas-liquid mixed refrigerant. The compressed gas-liquid mixed refrigerant enters the first heat exchanger 21 through the third connecting pipeline 301, the first reversing valve 31 and the second pipeline 102 to process the compressed air entering the heat exchanger to reduce the dew point of the compressed air; after the dew point of the compressed air is reduced, the low-temperature and low-pressure gas-liquid mixed refrigerant absorbs heat to form a low-temperature and low-pressure gaseous refrigerant, which flows out through the fourth pipeline 201, enters the gas-liquid separator 7 through the second reversing valve 32 for gas-liquid separation, and then returns to the refrigeration compressor 1 through the sixth pipeline 203, thereby completing the heat exchange work of the first heat exchanger 21 and the deicing work of the second heat exchanger 22.

[0080] like Figure 2As shown, when the first heat exchanger 21 is frozen, the compressed air is stopped from being introduced into the first heat exchanger 21, and the compressed air is introduced into the second heat exchanger 22, and the internal fluid flow direction of the first reversing valve 31 and the second reversing valve 32 is switched at the same time. At this time, the first heat exchanger 21 is in a deicing state, and the second heat exchanger 22 is in a normal working heat exchange state: the first pipeline 101 is connected to the second pipeline 102, the fourth pipeline 201 is connected to the third connecting pipeline 301, the third connecting pipeline 301 is connected to the third pipeline 103, and the fifth pipeline 202 is connected to the sixth pipeline 203. The high-temperature and high-pressure refrigeration compressor 1 exhaust gas enters the first heat exchanger 21 through the first pipeline 101, the first reversing valve 31 and the second pipeline 102 for deicing. The medium-temperature gaseous (or gas-liquid mixed) refrigerant formed after deicing flows out from the fourth pipeline 201, and enters the condenser 4 through the second reversing valve 32 and the third connecting pipeline 301 to condense to form a medium-temperature liquid refrigerant, and then enters the throttling device 6 after being filtered by the drying filter 5 to throttle and cool down, forming a low-temperature and low-pressure gas-liquid mixed refrigerant. The low-temperature and low-pressure gas-liquid mixed refrigerant passes through the third connecting pipeline 301, The first reversing valve 31 and the third pipeline 103 enter the second heat exchanger 22 to cool the compressed air entering the second heat exchanger 22 to reduce the dew point of the compressed air in the second heat exchanger 22. After the dew point of the compressed air is reduced, the refrigerant absorbs heat to form a low-temperature and low-pressure gaseous refrigerant. The low-temperature and low-pressure gaseous refrigerant flows out through the fifth pipeline 202, and enters the gas-liquid separator 7 through the second reversing valve 32 for gas-liquid separation, and then returns to the inlet of the refrigeration compressor 1 through the sixth pipeline 203, thereby completing the deicing work of the first heat exchanger 21 and the heat exchange work of the second heat exchanger 22.

[0081] When the performance of the second heat exchanger 22 drops to a set value (for example, ice forms), the first heat exchanger 21 is switched back to perform heat exchange, and the second heat exchanger 22 performs deicing. The two modes are cycled, so that the refrigerated dryer can continue to operate in a high-performance range (lower dew point and lower pressure drop) for a long time.

[0082] In this embodiment, the dew point performance of the compressed air can reach -10°C to -20°C, thereby preventing the refrigerated dryer from failing while improving the performance of the refrigerated dryer.

[0083] It is understandable that when both second heat exchangers 22 do not need to be de-iced, any heat exchanger can be used for heat exchange to process high-temperature and high-pressure compressed air. For example, the first heat exchanger 21 can be used for heat exchange, compressed air is introduced into the first heat exchanger 21, and the high-temperature and high-pressure gaseous refrigerant formed after compression by the refrigeration compressor 1 is introduced into the second heat exchanger 22 through the first pipeline 101, the first reversing valve 31, and the third pipeline 103, and flows out through the fifth pipeline 202, and then enters the condenser 4, the drying filter 5 and the throttling device 6 in sequence through the second reversing valve 32 and the third connecting pipeline 301, and the formed low-temperature and low-pressure gas-liquid mixed refrigerant is transported to the first heat exchanger 21 through the third connecting pipeline 301, the first reversing valve 31 and the second pipeline 102 for heat exchange. The specific heat exchange process is similar to the above-mentioned first heat exchanger 21 for heat exchange and the second heat exchanger 22 for de-icing, and will not be repeated here. That is, when de-icing is not performed, the refrigerant passage of the second heat exchanger 22 is only used as a transport passage.

[0084] Figure 3 FIG. 2 is a control flow chart showing a control method for a refrigerated dryer according to an embodiment of the present invention. Figure 3 As shown, the embodiment of the present invention further provides a control method for the above-mentioned refrigerated dryer, comprising:

[0085] S1: Obtaining the gas inlet pressure of the gas inlet and the gas outlet pressure of the gas outlet of the refrigerated dryer;

[0086] S2: Calculating the pressure difference between the inlet pressure and the outlet pressure according to the inlet pressure and the outlet pressure;

[0087] S3: comparing the pressure difference with a preset pressure threshold;

[0088] S4: Based on the comparison result, the first refrigerant circulation circuit and the second refrigerant circulation circuit are controlled to switch between an on state and an off state.

[0089] The control method for a refrigerated dryer provided in an embodiment of the present invention controls the switching of the on and off states of the first refrigeration cycle loop and the second refrigeration cycle loop according to the detected pressure difference between the gas inlet and the gas outlet of the refrigerated dryer. When the air side channel of one of the heat exchangers is blocked or the heat exchanger cannot work normally due to ice formation on the heat exchanger, the heat exchanger that cannot work normally can be de-iced (defrosted) and switched to another heat exchanger for heat exchange work, thereby ensuring the normal heat exchange work of the refrigerated dryer, improving the performance of the refrigerated dryer and avoiding failure of the refrigerated dryer.

[0090] Figure 4 Another control flow chart of the control method of the refrigerated dryer according to the embodiment of the present invention is shown. Figure 4 As shown, combined with Figure 1 When the first refrigerant circulation circuit is turned on and the second refrigerant circulation circuit is turned off, the method specifically includes:

[0091] S11: obtaining a first gas inlet pressure of a gas inlet and a first gas outlet pressure of a gas outlet of the first heat exchanger 21;

[0092] S21: calculating a first pressure difference between the first inlet pressure and the first outlet pressure according to the first inlet pressure and the first outlet pressure;

[0093] S31: comparing the first pressure difference with a preset pressure threshold;

[0094] S41: If the first pressure difference is greater than the preset pressure threshold, the first refrigerant circulation circuit is controlled to be disconnected and the second refrigerant circulation circuit is controlled to be connected; if the first pressure difference is less than or equal to the first preset threshold, the first refrigerant circulation circuit is controlled to be connected and the second refrigerant circulation circuit is disconnected.

[0095] Specifically, when the refrigerated dryer is initially operated, the first heat exchanger 21 is used for heat exchange by default, that is, compressed air is continuously introduced into the first heat exchanger 21 to keep the first heat exchanger 21 in a heat exchange state, and the pressure of the inlet and outlet of the first heat exchanger 21 is detected in real time by the pressure sensors arranged at the gas inlet and gas outlet of the first heat exchanger 21. When it is detected that the first pressure difference between the inlet and outlet is greater than the preset pressure threshold, it is determined that the first heat exchanger 21 may be frozen or the ice has reached a certain degree, and the first heat exchanger 21 needs to be de-iced. Ice, at this time, stop passing compressed air into the first heat exchanger 21, and control the first refrigerant circulation loop to be disconnected, so that the first heat exchanger 21 enters the deicing state; at the same time, control the second refrigerant circulation loop to be turned on, and pass compressed air into the second heat exchanger 22, so that the second heat exchanger 22 enters the heat exchange state for heat exchange; when it is detected that the first pressure difference between the inlet and outlet is less than or equal to the preset pressure threshold, control the first refrigerant circulation loop to remain turned on, and continue to detect the inlet and outlet pressures of the first heat exchanger 21.

[0096] like Figure 1As shown, the first refrigerant circulation circuit is connected, which means that: the first pipeline 101 is connected to the third pipeline 103, the fifth pipeline 202 is connected to the third connecting pipeline 301, the third connecting pipeline 301 is connected to the second pipeline 102, and the fourth pipeline 201 is connected to the sixth pipeline 203. When the refrigerated dryer is initially working, the high-temperature and high-pressure gaseous refrigerant formed after being compressed by the refrigeration compressor 1 first enters the second heat exchanger 22 through the first pipeline 101 and the third pipeline 103 to de-ice the second heat exchanger 22, and the refrigerant after de-icing the second heat exchanger 22 flows out through the fifth pipeline 202 and enters the first heat exchanger 21 for heat exchange, thereby realizing heat exchange of the first heat exchanger 21 and de-icing of the second heat exchanger 22. That is, when the refrigerated dryer is in the initial working state, it can be defaulted to use the first heat exchanger 21 for heat exchange and the second heat exchanger 22 for de-icing. At this time, it is determined whether the operation of the heat exchanger needs to be switched through steps S11 to S41.

[0097] It is understandable that when the refrigerated dryer is in the initial working state, no matter whether ice is formed in the second heat exchanger 22 , the refrigerant compressed by the refrigeration compressor 1 first enters the second heat exchanger 22 through the first pipeline 101 and the third pipeline.

[0098] In this embodiment, the pressure difference mainly refers to the pressure drop caused by energy loss when the compressed air flows in the gas pipeline.

[0099] Figure 5 FIG. 2 shows another control flow chart of the control method of the refrigerated dryer according to the embodiment of the present invention. Figure 5 As shown, combined with Figure 2 When the second refrigerant circulation circuit is connected and the first refrigerant circulation circuit is disconnected, the method specifically includes:

[0100] S12: obtaining a second gas inlet pressure of the gas inlet and a second gas outlet pressure of the gas outlet of the second heat exchanger 22;

[0101] S22: Calculating a second pressure difference between the second inlet pressure and the second outlet pressure according to the second inlet pressure and the second outlet pressure

[0102] S32: comparing the second pressure difference with a preset pressure threshold;

[0103] S42: If the second pressure difference is greater than the preset pressure threshold, the second refrigerant circulation circuit is controlled to be disconnected and the first refrigerant circulation circuit is connected; if the second pressure difference is less than or equal to the preset pressure threshold, the second refrigerant circulation circuit is controlled to be connected and the first refrigerant circulation circuit is disconnected.

[0104] like Figure 2As shown, when the first refrigerant circulation loop is controlled to be disconnected through step S41, so that the first heat exchanger 21 enters the deicing state, and the second refrigerant circulation loop is controlled to be connected, so that the second heat exchanger 22 enters the heat exchange state, the above step S12 is executed, compressed air is continuously introduced into the second heat exchanger 22, and the pressure of the inlet and outlet of the second heat exchanger 22 is detected in real time through the pressure sensors arranged at the gas inlet and gas outlet of the second heat exchanger 22. When it is detected that the second pressure difference between the inlet and outlet of the second heat exchanger 22 is greater than the preset pressure threshold, it is determined that the second heat exchanger 22 may be frozen or the freezing reaches a certain degree. , it is necessary to de-ice the second heat exchanger 22. At this time, stop introducing compressed air into the second heat exchanger 22, and control the second refrigerant circulation loop to be disconnected, so that the second heat exchanger 22 enters a de-icing state; at the same time, control the first refrigerant circulation loop to be connected, return to step S11 to introduce compressed air into the first heat exchanger 21, so that the first heat exchanger 21 enters a heat exchange state for heat exchange, and detects a first air inlet pressure of the gas inlet and a second air outlet pressure of the gas outlet of the first heat exchanger 21, and repeats this process to continuously realize alternating heat exchange (alternating de-icing) between the first heat exchanger 21 and the second heat exchanger 22.

[0105] like Figure 2 As shown, the second refrigerant circulation circuit is connected, which means that the first pipeline 101 is connected to the second pipeline 102, the fourth pipeline 201 is connected to the third connecting pipeline 301, the third connecting pipeline 301 is connected to the third pipeline 103, and the fifth pipeline 202 is connected to the sixth pipeline 203, so that the high-temperature and high-pressure gaseous refrigerant formed after compression by the refrigeration compressor 1 first enters the first heat exchanger 21 for deicing, and then enters the second heat exchanger 22 for heat exchange.

[0106] The above-mentioned preset pressure threshold is the pressure range value under the normal working condition of the refrigerated dryer, which can be specifically determined according to the heat exchange efficiency of the corresponding heat exchanger, etc., and is not specifically limited in the present invention. It can be understood that since the first refrigerant circulation circuit or the second refrigerant circulation circuit is controlled to be connected by controlling the first reversing valve 31 and the second reversing valve 32 in the above-mentioned embodiment, when the first refrigerant circulation circuit is controlled to be connected, it can be determined that the second refrigerant circulation circuit is disconnected; when the second refrigerant circulation circuit is controlled to be connected, it can be determined that the first refrigerant circulation circuit is disconnected. In this way, through the cooperation of the first reversing valve 31 and the second reversing valve 32, the alternating connection operation of the first refrigerant circulation circuit and the second refrigerant circulation circuit can be guaranteed, and the control is convenient and accurate.

[0107] In this embodiment, the conduction state of the first refrigerant circulation circuit and the second refrigerant circulation circuit are switched according to the pressure difference between the gas inlet pressure of the gas inlet and the gas outlet pressure of the gas outlet of the refrigerated dryer detected in real time, so that the first heat exchanger 21 and the second heat exchanger 22 work alternately, which can ensure that the refrigerated dryer is always in a better working performance state when working.

[0108] The control method of the refrigerated dryer provided in the embodiment of the present invention corresponds to the refrigerated dryer in the above embodiment. Any optional items in the refrigerated dryer embodiment are also applicable to the embodiment of the control method of the refrigerated dryer, which will not be described in detail here.

[0109] The above embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention. The protection scope of the present invention is defined by the claims. Those skilled in the art may make various modifications or equivalent substitutions to the present invention within the essence and protection scope of the present invention, and such modifications or equivalent substitutions shall also be deemed to fall within the protection scope of the present invention.

Claims

1. A refrigerated dryer, characterized in that: include: Refrigeration compressors; The first heat exchanger and the second heat exchanger each include a refrigerant inlet and a refrigerant outlet, and the refrigeration compressor, the first heat exchanger and the second heat exchanger are interconnected through a pipeline; A control valve is provided on the pipeline to connect the refrigeration compressor, the second heat exchanger, and the first heat exchanger in sequence to form a first refrigerant circulation loop or to connect the refrigeration compressor, the first heat exchanger, and the second heat exchanger in sequence to form a second refrigerant circulation loop, so as to realize alternating heat exchange between the first heat exchanger and the second heat exchanger; The refrigerated dryer further comprises a condenser, a drying filter and a throttling device which are sequentially connected through pipelines, the inlet of the condenser is connected to the refrigerant outlet of the first heat exchanger or the second heat exchanger, and the outlet of the throttling device is connected to the refrigerant inlet of the second heat exchanger or the first heat exchanger; The refrigerated dryer further includes a gas-liquid separator disposed between a refrigerant outlet of the first heat exchanger or the second heat exchanger and an inlet of the refrigeration compressor.

2. The refrigerated dryer according to claim 1, characterized in that: The control valve comprises: A first reversing valve is provided on a first connecting pipeline between the refrigerant inlet of the first heat exchanger and the second heat exchanger and the outlet of the refrigeration compressor; a second reversing valve, provided on a second connecting pipeline between the refrigerant outlets of the first heat exchanger and the second heat exchanger and the inlet of the refrigeration compressor, and the first connecting pipeline and the second connecting pipeline are in communication; The flow direction of the refrigerant can be switched by adjusting the first reversing valve and the second reversing valve to form the first refrigerant circulation circuit or the second refrigerant circulation circuit.

3. The refrigerated dryer according to claim 2, characterized in that: The first reversing valve and the second reversing valve are four-way reversing valves; The first connecting pipeline includes a first pipeline provided between the outlet of the refrigeration compressor and the first inlet of the first reversing valve, a second pipeline provided between the first outlet of the first reversing valve and the refrigerant inlet of the first heat exchanger, and a third pipeline provided between the second outlet of the first reversing valve and the refrigerant inlet of the second heat exchanger, and the first pipeline and the second pipeline can be connected or the first pipeline and the third pipeline can be connected by switching the first reversing valve; The second connecting pipeline includes a fourth pipeline provided between the refrigerant outlet of the first heat exchanger and the first inlet of the second reversing valve, a fifth pipeline provided between the refrigerant outlet of the second heat exchanger and the second inlet of the second reversing valve, and a sixth pipeline provided between the first outlet of the second reversing valve and the inlet of the refrigeration compressor, and the fourth pipeline and the sixth pipeline can be connected or the fifth pipeline and the sixth pipeline can be connected by switching the second reversing valve; The second inlet of the first reversing valve is connected to the second outlet of the second reversing valve via a third connecting pipeline.

4. The refrigerated dryer according to claim 1, characterized in that: The first heat exchanger and the second heat exchanger further include a gas inlet and a gas outlet, respectively, and external compressed air enters the first heat exchanger or the second heat exchanger through the gas inlet for heat exchange and flows out from the gas outlet; The gas inlets of the first heat exchanger and the second heat exchanger are respectively connected to compressed air inlet pipelines, and the gas outlets of the first heat exchanger and the second heat exchanger are respectively connected to compressed air outlet pipelines.

5. The refrigerated dryer according to claim 4, characterized in that: The compressed air inlet pipeline includes a compressed air inlet main pipe, and compressed air inlet branches connected to the compressed air inlet main pipe and respectively connected to the gas inlets of the first heat exchanger and the second heat exchanger; the compressed air outlet pipeline includes compressed air outlet branches respectively connected to the gas outlets of the first heat exchanger and the second heat exchanger, and a compressed air outlet main pipe respectively connected to the compressed air outlet branches.

6. The refrigerated dryer according to claim 5, characterized in that: The compressed air inlet branch pipe and the compressed air outlet branch pipe are provided with gas regulating valves.

7. The refrigerated dryer according to claim 5, characterized in that: The compressed air intake manifold is provided with a first pressure sensor, and the compressed air exhaust manifold is provided with a second pressure sensor.

8. The refrigerated dryer according to claim 2, characterized in that: The first reversing valve and the second reversing valve are both solenoid valves.

9. A control method for a refrigerated dryer according to any one of claims 1 to 8, characterized in that: The method comprises: Obtaining the gas inlet pressure and the gas outlet pressure of the gas inlet of the refrigerated dryer; Calculating the pressure difference between the inlet pressure and the outlet pressure according to the inlet pressure and the outlet pressure; comparing the pressure difference with a preset threshold; Based on the comparison result, the first refrigerant circulation circuit and the second refrigerant circulation circuit are controlled to switch between an on state and an off state.

10. The control method of a refrigerated dryer according to claim 9, characterized in that: When the first refrigerant circulation circuit is turned on and the second refrigerant circulation circuit is turned off, the control method specifically includes: Obtaining a first gas inlet pressure of a gas inlet and a first gas outlet pressure of a gas outlet of the first heat exchanger; Calculating a first pressure difference between the first inlet pressure and the first outlet pressure according to the first inlet pressure and the first outlet pressure; comparing the first pressure difference with a preset pressure threshold; If the first pressure difference is greater than the preset pressure threshold, the first refrigerant circulation circuit is controlled to be disconnected and the second refrigerant circulation circuit is controlled to be connected; if the first pressure difference is less than or equal to the preset pressure threshold, the first refrigerant circulation circuit is controlled to be connected and the second refrigerant circulation circuit is disconnected.

11. The control method of a refrigerated dryer according to claim 9, characterized in that: When the second refrigerant circulation circuit is turned on and the first refrigerant circulation circuit is turned off, the control method specifically includes: Obtaining a second gas inlet pressure of a gas inlet and a second gas outlet pressure of a gas outlet of the second heat exchanger; Calculating a second pressure difference between the second inlet pressure and the second outlet pressure according to the second inlet pressure and the second outlet pressure; comparing the second pressure difference with a preset pressure threshold; If the second pressure difference is greater than the preset pressure threshold, the second refrigerant circulation circuit is controlled to be disconnected and the first refrigerant circulation circuit is connected; if the second pressure difference is less than or equal to the preset pressure threshold, the second refrigerant circulation circuit is controlled to be connected and the first refrigerant circulation circuit is disconnected.

Images