Refrigerating system of freeze dryer and heat exchange method of refrigerating system

Abstract

The invention discloses a refrigeration system of a freeze dryer and a heat exchange method of the refrigeration system. The refrigeration system comprises a freeze-drying box body, a condenser body, a condenser refrigeration heat exchange module, a freeze-drying box refrigeration heat exchange module, a liquid nitrogen input pipeline and an air return pipeline. The condenser body communicates with the freeze-drying box body, and a heat exchange assembly used for condensing water vapor is arranged in the condenser body. The condenser refrigeration heat exchange module communicates with the liquid nitrogen input pipeline and an inlet of the heat exchange assembly and is used for conducting multi-stage heat exchange on the condenser body. The freeze-drying box refrigeration heat exchange module communicates with the liquid nitrogen input pipeline and is used for conducting multi-stage heat exchange on the freeze-drying box body. The air return pipeline communicates with an outlet of the heat exchange assembly and an outlet of the freeze-drying box refrigeration heat exchange module. Through the arrangement, the functions of reducing the refrigeration inertia and increasing the temperature response speed are achieved, the heat exchange process can be prolonged so as to improve the liquid nitrogen utilization efficiency, and the purpose of reducing the equipment and maintenance cost is achieved.

Description

Technical Field

[0001] The present invention relates to the field of freeze dryers, and in particular to a refrigeration system of a freeze dryer and a heat exchange method thereof. Background Art

[0002] In the freeze-drying industry, liquid nitrogen refrigeration technology, due to its environmentally friendly and efficient properties, is widely used in applications such as pharmaceuticals, where refrigeration precision is critical. Currently, mainstream freeze-drying systems utilize shell-and-tube cryogenic heat exchangers as core components, providing cooling for the freeze-drying chamber and condenser through indirect liquid nitrogen refrigeration, direct expansion refrigeration, or a combination with a compressor.

[0003] However, existing shell-and-tube heat exchanger systems have certain technical limitations. First, the large volume and mass of the shell-and-tube structure lead to significant refrigeration inertia. During system startup, shutdown, or adjustment, the temperature response lags, making it difficult to quickly adapt to changes in process parameters. Second, the condenser often uses liquid nitrogen direct expansion refrigeration technology. When liquid nitrogen directly absorbs heat and vaporizes within the coil, the temperature of the contact area fluctuates violently, resulting in large temperature differences across the coil, affecting the uniformity of water vapor condensation and ice capture, and thus affecting the operating conditions of the freeze-drying process. Third, the heat exchange process between liquid nitrogen and the heat transfer medium (such as silicone oil) in the shell-and-tube heat exchanger is highly coupled. When operating conditions change and the liquid nitrogen flow rate does not match the actual cooling capacity demand, the liquid nitrogen is prone to insufficient vaporization, reducing energy efficiency and increasing operating costs. In addition, the large weight and volume of the shell-and-tube heat exchanger are not conducive to integrated and modular applications.

[0004] Therefore, a refrigeration system of a freeze dryer and a heat exchange method thereof are needed to solve the above problems. Summary of the Invention

[0005] The object of the present invention is to provide a refrigeration system for a freeze dryer and a heat exchange method thereof, so as to reduce the volume and mass of the refrigeration system, thereby achieving the purpose of reducing refrigeration inertia and improving temperature response speed. It can also avoid the risk of freezing of the heat transfer medium due to a sharp drop in the temperature of the heat transfer medium caused by phase change of liquid nitrogen when liquid nitrogen directly cools the heat transfer medium through a plate heat exchanger. It can also avoid the problem of large temperature fluctuations at the coil outlet caused by temperature differences caused by direct contact between liquid nitrogen and the coil, thereby achieving the function of extending the heat exchange process to improve the utilization efficiency of liquid nitrogen and reduce equipment and maintenance costs.

[0006] In order to solve the above technical problems, the present invention provides a refrigeration system for a freeze dryer, comprising a freeze drying chamber body, a condenser body, a condenser refrigeration and heat exchange module, a freeze drying chamber refrigeration and heat exchange module, a liquid nitrogen input pipeline, and a return air pipeline;

[0007] The condenser body is in communication with the freeze drying chamber body and has a built-in heat exchange component for condensing water vapor;

[0008] The condenser refrigeration and heat exchange module is in communication with the liquid nitrogen input pipeline and the inlet of the heat exchange component, and is used to perform multi-stage heat exchange on the condenser body;

[0009] The freeze drying chamber refrigeration and heat exchange module is connected to the liquid nitrogen input pipeline and is used to perform multi-stage heat exchange on the freeze drying chamber body;

[0010] The return air pipeline is communicated with the outlet of the heat exchange component and the outlet of the freeze drying box refrigeration and heat exchange module.

[0011] Furthermore, the condenser refrigeration and heat exchange module includes multiple groups of first plate heat exchangers arranged in parallel;

[0012] The first plate heat exchanger has a first flow channel for gasifying liquid nitrogen and a second flow channel for circulating nitrogen;

[0013] The inlets and outlets of the plurality of first flow channels are respectively connected to the liquid nitrogen input pipeline and the inlet of the heat exchange component;

[0014] The outlets of the plurality of first flow channels are connected to the inlet of the heat exchange component through a first confluence pipe;

[0015] Both ends of the plurality of second flow channels are connected to the heat exchange component to form a first heat exchange loop, and the first heat exchange loop is used for performing multi-stage heat exchange with the first flow channel.

[0016] Furthermore, the heat exchange assembly includes multiple groups of coils arranged in series;

[0017] The outlets and inlets of two adjacent groups of the coils are respectively connected to the same second flow channel through a pipeline to form the first heat exchange circuit;

[0018] The inlet of the upstream coil is connected to the output end of the first plate heat exchanger, and the outlet of the downstream coil is connected to the return air pipeline;

[0019] The ratio of the number of the first plate heat exchangers to the number of the coils is N:N+1.

[0020] Furthermore, the freeze drying chamber refrigeration and heat exchange module includes multiple sets of second plate heat exchangers and gas nitrogen-heat conducting medium plate heat exchangers arranged in parallel;

[0021] The second plate heat exchanger has a third flow channel for gasifying liquid nitrogen and a fourth flow channel for circulating nitrogen;

[0022] The inlets and outlets of the plurality of third flow channels are respectively connected to the liquid nitrogen input pipeline and the nitrogen flow channel of the upstream gas nitrogen-heat-conducting medium plate heat exchanger;

[0023] The outlets of the plurality of third flow channels are connected to the nitrogen flow channel of the upstream gas-nitrogen-heat-conducting medium plate heat exchanger through a second confluence pipe;

[0024] A plurality of nitrogen flow channels of the gas-nitrogen-heat-conducting medium plate heat exchanger are connected to the fourth flow channel to form a second heat exchange circuit, and the second heat exchange circuit is used to perform multi-stage heat exchange with the third flow channel and the heat-conducting medium flow channel of the gas-nitrogen-heat-conducting medium plate heat exchanger;

[0025] Wherein, a first heat-conducting medium circulation loop is connected between the heat-conducting medium flow channel of the gas-nitrogen-heat-conducting medium plate heat exchanger and the freeze-drying chamber body;

[0026] The return air pipeline is communicated with the outlet of the heat exchange component and the outlet of the nitrogen flow channel of the downstream gas nitrogen-heat conducting medium plate heat exchanger.

[0027] Furthermore, the return air pipeline has a first return air branch pipeline connected to the outlet of the heat exchange component and a second return air branch pipeline connected to the nitrogen flow channel outlet of the downstream gas nitrogen-heat transfer medium plate heat exchanger;

[0028] The first return air branch pipeline and the second return air branch pipeline are both provided with a temperature sensor and a control valve.

[0029] Furthermore, the ratio of the number of the second plate heat exchangers to the number of the gas nitrogen-heat transfer medium plate heat exchangers is N:N+1.

[0030] Furthermore, the first heat transfer medium circulation loop is provided with a balancing cylinder, a circulation pump and a heater in sequence along the heat transfer medium circulation direction.

[0031] On the other hand, the present invention also proposes another refrigeration system for a freeze dryer, comprising a freeze drying chamber body, a condenser body, two sets of refrigeration and heat exchange modules, a liquid nitrogen input pipeline, and a return air pipeline;

[0032] The condenser body is in communication with the freeze drying chamber body, and both the condenser body and the freeze drying chamber body have a second heat transfer medium circulation loop;

[0033] The two groups of refrigeration and heat exchange modules each include multiple groups of plate heat exchanger bodies and gas nitrogen-heat transfer medium plate heat exchangers arranged in parallel, which are used to cool and exchange heat with the second heat transfer medium circulation loop of the condenser body and the freeze drying chamber body respectively;

[0034] The plate heat exchanger body has a fifth flow channel for gasifying liquid nitrogen and a sixth flow channel for circulating nitrogen;

[0035] The inlet and outlet of the fifth flow channel are respectively connected to the liquid nitrogen input pipeline and the nitrogen flow channel of the gas nitrogen-heat conducting medium plate heat exchanger;

[0036] A plurality of nitrogen flow channels of the gas-nitrogen-heat-conducting medium plate heat exchanger are connected to the sixth flow channel to form a third heat exchange circuit, wherein the third heat exchange circuit is used for performing multi-stage heat exchange with the fifth flow channel and the heat-conducting medium flow channel of the gas-nitrogen-heat-conducting medium plate heat exchanger;

[0037] Wherein, the heat transfer medium flow channels of the plurality of gas-nitrogen-heat transfer medium plate heat exchangers are connected to the second heat transfer medium circulation loop.

[0038] Furthermore, a connecting pipe is provided between the two second heat transfer medium circulation loops, and a balancing cylinder is provided on the connecting pipe;

[0039] The two second heat transfer medium circulation loops are both provided with a circulation pump.

[0040] Furthermore, the heat transfer medium in the second heat transfer medium circulation loop is silicone oil.

[0041] On the other hand, the present invention also proposes a heat exchange method for a freeze dryer, which is applied to the refrigeration system of the freeze dryer described above, including a multi-stage heat exchange method on the condenser side and a multi-stage heat exchange method on the freeze drying chamber side;

[0042] The multi-stage heat exchange method on the condenser side includes the following steps:

[0043] S1, liquid nitrogen enters the first flow channel of multiple first plate heat exchangers through the liquid nitrogen input pipeline, absorbs heat and vaporizes to form nitrogen, and then converges and enters the inlet of the heat exchange component;

[0044] S2: Nitrogen flows through the upstream coil of the heat exchange assembly and exchanges heat with the water vapor in the condenser body. The nitrogen then flows back to the second flow channel of the first plate heat exchanger to exchange heat with the liquid nitrogen in the first flow channel. After completing the heat exchange, the nitrogen flows into the next coil and exchanges heat with the water vapor in the condenser body again, thereby forming a first heat exchange loop that performs multi-stage alternating heat exchange with the first flow channel and the water vapor in the condenser body.

[0045] S3. After the nitrogen passes through multiple sets of coils, it is discharged from the outlet of the downstream coil through the return air pipeline;

[0046] The multi-stage heat exchange method on the freeze drying chamber side comprises the following steps:

[0047] T1, liquid nitrogen enters the third flow channel of the second plate heat exchanger through the liquid nitrogen input pipeline, absorbs heat and vaporizes to form nitrogen gas, and then merges and enters the nitrogen flow channel of the upstream gas nitrogen-heat transfer medium plate heat exchanger;

[0048] T2, the nitrogen in the nitrogen flow channel exchanges heat with the heat-conducting medium in the heat-conducting medium flow channel, then flows back to the fourth flow channel of the second plate heat exchanger, exchanges heat with the liquid nitrogen in the third flow channel, and after completing the heat exchange, flows into the nitrogen flow channel of the next-stage gas nitrogen-heat-conducting medium plate heat exchanger, thereby forming a second heat exchange loop that performs multi-stage alternating heat exchange with the third flow channel and the first heat-conducting medium circulation loop;

[0049] T3. After the nitrogen flows through multiple groups of gas nitrogen-heat transfer medium plate heat exchangers in sequence, it is discharged from the nitrogen flow channel outlet of the downstream gas nitrogen-heat transfer medium plate heat exchanger through the return air pipeline. At the same time, the heat transfer medium cools the freeze drying chamber body through the first heat transfer medium circulation loop.

[0050] Compared with the prior art, the present invention has at least the following beneficial effects:

[0051] By setting up multiple sets of parallel first plate heat exchangers to replace the traditional shell-and-tube heat exchangers, the volume and mass of the refrigeration system are significantly reduced, the thermal inertia is reduced, and the system can quickly respond to changes in process parameters and reduce temperature regulation lag; and by configuring the first plate heat exchanger with a first flow channel and a second flow channel, and forming a first heat exchange loop with the heat exchange component, after the liquid nitrogen is vaporized in the first flow channel, the nitrogen first exchanges heat with the water vapor in the heat exchange component, and then flows back to the second flow channel to perform multi-stage alternating heat exchange with the newly input liquid nitrogen, thereby avoiding direct contact of the liquid nitrogen with the heat exchange component. The problem of large temperature fluctuations at the coil outlet caused by temperature differences due to component contact is solved, thereby ensuring the quality stability of freeze-dried products. In addition, by configuring the second plate heat exchanger with a third flow channel and a fourth flow channel, and forming a second heat exchange loop with the gas nitrogen-heat transfer medium plate heat exchanger, the nitrogen gas after being vaporized in the third flow channel can flow back to the fourth flow channel to exchange heat with the newly input liquid nitrogen again after passing through the nitrogen flow channel to exchange heat with the heat transfer medium, thereby extending the heat exchange process and realizing the cascade utilization of cooling capacity, thereby improving the utilization efficiency of liquid nitrogen and reducing energy waste and operating costs.

[0052] In addition, by configuring the second plate heat exchanger with a third flow channel and a fourth flow channel, and forming a second heat exchange circuit with the gas nitrogen-heat transfer medium plate heat exchanger, it is also possible to avoid the risk of the heat transfer medium freezing due to a sharp drop in temperature caused by the phase change of liquid nitrogen when the liquid nitrogen directly cools the heat transfer medium through the plate heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 Schematic diagram of the structure of the refrigeration system of the freeze dryer in Example 1 of the present invention;

[0054] Figure 2 This is a schematic diagram of the structure of the refrigeration system of the freeze dryer in Example 2 of the present invention.

[0055] Figure numbers: 1, freeze drying chamber body; 2, condenser body; 21, coil; 3, liquid nitrogen input pipeline; 4, return air pipeline; 41, first return air branch pipeline; 42, second return air branch pipeline; 43, temperature sensor; 44, control valve; 5, first plate heat exchanger; 51, first flow channel; 511, first confluence pipeline; 52, second flow channel; 6, first heat exchange circuit; 7, second plate heat exchanger; 71, third flow channel; 711, second Converging pipe; 72, fourth flow channel; 8, gas nitrogen-heat transfer medium plate heat exchanger; 81, nitrogen flow channel; 82, heat transfer medium flow channel; 9, second heat exchange circuit; 10, first heat transfer medium circulation circuit; 101, balancing cylinder; 102, circulating pump; 103, heater; 11, second heat transfer medium circulation circuit; 12, plate heat exchanger body; 121, fifth flow channel; 122, sixth flow channel; 13, third heat exchange circuit; 14, connecting pipe. DETAILED DESCRIPTION

[0056] The refrigeration system and heat exchange method of the freeze dryer of the present invention will be described in more detail below with reference to schematic diagrams, which illustrate preferred embodiments of the present invention. It should be understood that those skilled in the art may modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as being generally known to those skilled in the art and not intended to limit the present invention.

[0057] Moreover, based on the teachings of this specification, those skilled in the art may form new technical solutions by cross-combining different implementation methods without generating technical contradictions. Such variations should be deemed to fall within the scope of protection of this patent.

[0058] The following paragraphs describe the present invention in more detail by way of example with reference to the accompanying drawings. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are provided solely for the purpose of assisting in the description of the embodiments of the present invention.

[0059] Example 1

[0060] like Figure 1 As shown, an embodiment of the present invention proposes a refrigeration system for a freeze dryer, including a freeze drying chamber body 1, a condenser body 2, a condenser refrigeration and heat exchange module, a freeze drying chamber refrigeration and heat exchange module, a liquid nitrogen input pipeline 3 and a return air pipeline 4.

[0061] Specifically, the condenser body 2 is communicated with the freeze drying chamber body 1 and has a built-in heat exchange component for condensing water vapor.

[0062] The condenser refrigeration and heat exchange module includes a plurality of first plate heat exchangers 5 arranged in parallel.

[0063] Furthermore, the first plate heat exchanger 5 has a first flow channel 51 for vaporizing liquid nitrogen and a second flow channel 52 for circulating nitrogen gas. That is, the heat exchange operation between liquid nitrogen and nitrogen gas is performed by providing the first flow channel 51 and the second flow channel 52 independently.

[0064] It should be noted that the inlets and outlets of the multiple first flow channels 51 are connected to the liquid nitrogen input pipeline 3 and the inlet of the heat exchange component, respectively. Because the inlet of the first flow channel 51 is connected to the liquid nitrogen input pipeline 3 and the outlet is connected to the inlet of the heat exchange component, liquid nitrogen can directly enter the first flow channel 51 to complete heat absorption and vaporization. The generated low-temperature nitrogen can be directly transported to the heat exchange component to provide cooling for the condenser body 2, thereby achieving the initial transfer of liquid nitrogen cooling to the condenser body 2, laying the foundation for subsequent heat exchange.

[0065] Both ends of the plurality of second flow channels 52 are connected to the heat exchange assembly, forming a first heat exchange loop 6, which is used for multi-stage heat exchange with the first flow channel 51. By connecting the second flow channels 52 to the heat exchange assembly to form the first heat exchange loop 6, the nitrogen that has passed through the heat exchange assembly can flow back to the second flow channels 52 and exchange heat again with the new liquid nitrogen in the first flow channel 51, thereby achieving cascaded utilization of cooling capacity, improving the utilization rate of liquid nitrogen cooling capacity, and avoiding cooling capacity waste caused by direct nitrogen discharge.

[0066] It should also be noted that, in this embodiment, by providing a first plate heat exchanger 5 to replace the traditional shell-and-tube heat exchanger, the volume and mass of the refrigeration system are significantly reduced, the thermal inertia is reduced, and thus it can quickly respond to changes in process parameters and reduce temperature regulation lag.

[0067] The freeze-drying chamber refrigeration and heat exchange module includes multiple sets of parallel second plate heat exchangers 7 and gas nitrogen-heat-conducting medium plate heat exchangers 8. By combining multiple sets of parallel second plate heat exchangers 7 and gas nitrogen-heat-conducting medium plate heat exchangers 8 to form the freeze-drying chamber refrigeration and heat exchange module, the refrigeration requirements of the freeze-drying chamber body 1 can be distributed through a modular structure, thereby improving the stability and flexibility of the system refrigeration and facilitating the adjustment of the cooling capacity according to the freeze-drying chamber load.

[0068] The second plate heat exchanger 7 has a third flow channel 71 for vaporizing liquid nitrogen and a fourth flow channel 72 for circulating nitrogen. By providing the second plate heat exchanger 7 with the third flow channel 71 and the fourth flow channel 72, the liquid nitrogen can absorb heat and vaporize in the third flow channel 71 to produce low-temperature nitrogen. At the same time, an independent channel (i.e., the fourth flow channel 72) is provided for the subsequent circulation heat exchange of the nitrogen. This separates the liquid nitrogen vaporization process from the secondary heat exchange process of the nitrogen, ensuring that the liquid nitrogen is fully vaporized to release cold energy, creating conditions for subsequent multi-stage heat exchange, and helping to improve the accuracy of cold energy transfer.

[0069] Specifically, the inlets and outlets of the plurality of third flow channels 71 are respectively connected to the liquid nitrogen input pipeline 3 and the nitrogen flow channel 81 of the upstream gas nitrogen-heat conducting medium plate heat exchanger 8 for nitrogen transfer.

[0070] It should also be noted that the nitrogen flow channels 81 of the multiple sets of gas-nitrogen-heat-conducting medium plate heat exchangers 8 are connected to the fourth flow channel 72 to form a second heat exchange loop 9. This second heat exchange loop 9 is used for multi-stage heat exchange with the third flow channel 71 and the heat-conducting medium flow channel 82 of the gas-nitrogen-heat-conducting medium plate heat exchanger 8. By connecting the nitrogen flow channels 81 with the fourth flow channel 72 to form the second heat exchange loop 9, nitrogen that has passed through the gas-nitrogen-heat-conducting medium plate heat exchanger 8 can flow back to the fourth flow channel 72 of the second plate heat exchanger 7, where it can exchange heat again with the new liquid nitrogen in the third flow channel 71. This cyclic heat exchange method extends the cold transfer path, allowing the cold energy of the liquid nitrogen to be fully released to the heat-conducting medium in the heat-conducting medium flow channel 82 through multi-stage heat exchange, thereby improving cold energy utilization efficiency.

[0071] Among them, a first heat-conducting medium circulation loop 10 is connected between the heat-conducting medium flow channel 82 of the gas nitrogen-heat-conducting medium plate heat exchanger 8 and the freeze-drying chamber body 1. The connection between the heat-conducting medium flow channel 82 and the first heat-conducting medium circulation loop 10 transports the heat-conducting medium (such as silicone oil) that has absorbed cold energy to the freeze-drying chamber body 1, realizing indirect transfer of cold energy from the heat exchanger to the freeze-drying chamber body 1. The indirect refrigeration method avoids direct contact between liquid nitrogen and the freeze-drying chamber body 1, reduces temperature fluctuations, helps maintain the temperature stability in the freeze-drying chamber body 1, and ensures the precise implementation of the freeze-drying process.

[0072] The return gas line 4 communicates with the outlet of the heat exchange assembly and the outlet of the nitrogen flow channel 81 of the downstream gas-nitrogen-heat-conducting medium plate heat exchanger 8. This return gas line 4 provides a discharge channel for the nitrogen that has released its cooling capacity after multiple stages of heat exchange, ensuring smooth gas circulation within the system. Furthermore, centralized processing of the return gas avoids energy waste and environmental impacts caused by direct nitrogen discharge, and also provides a foundation for potential subsequent nitrogen recovery and utilization.

[0073] This device replaces the traditional shell-and-tube heat exchanger by providing multiple sets of parallel first plate heat exchangers 5, so that the volume and mass of the refrigeration system are significantly reduced, the thermal inertia is reduced, and the device can quickly respond to changes in process parameters and reduce temperature regulation lag.

[0074] Furthermore, by configuring the first plate heat exchanger 5 with a first flow channel 51 and a second flow channel 52, and forming a first heat exchange loop 6 with the heat exchange component, after the liquid nitrogen is vaporized in the first flow channel 51, the nitrogen first exchanges heat with the water vapor in the heat exchange component, and then flows back to the second flow channel 52 to perform multi-stage alternating heat exchange with the newly input liquid nitrogen. This avoids the local drastic temperature difference caused by direct contact of the liquid nitrogen with the heat exchange component, thereby achieving the purpose of improving the uniformity of ice capture in the condenser body 2 and ensuring the quality stability of the freeze-dried product.

[0075] In addition, by configuring the second plate heat exchanger 7 with a third flow channel 71 and a fourth flow channel 72, and forming a second heat exchange loop 9 with the gas-nitrogen-heat-conducting medium plate heat exchanger 8, the nitrogen gas after being vaporized in the third flow channel 71 can be returned to the fourth flow channel 72 to exchange heat with the newly input liquid nitrogen again after passing through the nitrogen flow channel 81 to exchange heat with the heat-conducting medium. This extends the heat exchange process and realizes the cascade utilization of cooling capacity, thereby improving the utilization efficiency of liquid nitrogen and reducing energy waste and operating costs.

[0076] In this embodiment, the heat exchange assembly includes multiple groups of coils 21 arranged in series.

[0077] The outlets and inlets of two adjacent groups of coils 21 are respectively connected to the same second flow channel 52 through pipes to form the first heat exchange circuit 6. This allows the nitrogen to flow through the coils 21, exchange heat with the water vapor in the condenser body 2, and then flow back to the first plate heat exchanger 5 through the second flow channel 52 to exchange heat with the new liquid nitrogen in the first flow channel 51 again. It then enters the next level of coils 21 and repeats the heat exchange process, thereby achieving the recycling of nitrogen and the cascade transfer of cooling capacity. This not only avoids the waste of cooling capacity caused by the direct discharge of nitrogen after a single heat exchange, but also extends the cooling capacity release path through multi-stage heat exchange, thereby improving the overall utilization efficiency of liquid nitrogen cooling capacity.

[0078] It should also be noted that the inlet of the upstream coil 21 is connected to the output end of the first plate heat exchanger 5, and the outlet of the downstream coil 21 is connected to the return air line 4. By connecting the inlet of the upstream coil 21 with the output end of the first plate heat exchanger 5, it is ensured that the low-temperature nitrogen gas generated by vaporization in the first flow channel 51 can directly enter the initial section of the coil 21, providing sufficient cooling capacity for the condenser. Connecting the outlet of the downstream coil 21 with the return air line 4 provides an exhaust channel for the nitrogen that has undergone multiple stages of heat exchange and has basically released all its cooling capacity, ensuring the smooth flow of gas in the entire first heat exchange circuit 6 and allowing the refrigeration process to operate continuously and stably.

[0079] In a specific example, the number of first plate heat exchangers 5 and coils 21 and the number of second plate heat exchangers 7 and gas nitrogen-heat transfer medium plate heat exchangers 8 are further limited to meet the application requirements of cyclic alternating heat exchange.

[0080] Specifically, the ratio of the number of the first plate heat exchangers 5 to the number of the coils 21, and the ratio of the number of the second plate heat exchangers 7 to the number of the gas-nitrogen-heat-conducting-medium plate heat exchangers 8, is N:N+1. That is, when there are two first plate heat exchangers 5 and two second plate heat exchangers 7, there are three corresponding coils 21 and three corresponding gas-nitrogen-heat-conducting-medium plate heat exchangers 8. This enables the first heat exchange circuit 6 and the second heat exchange circuit 9 to perform multi-stage alternating heat exchange operations, thereby improving the cooling effect.

[0081] In other embodiments, the return air pipeline 4 includes a first return air branch pipeline 41 communicating with the outlet of the heat exchange assembly, and a second return air branch pipeline 42 communicating with the outlet of the nitrogen flow channel 81 of the downstream gas-nitrogen-heat-conducting medium plate heat exchanger 8. Specifically, by providing the first return air branch pipeline 41 and the second return air branch pipeline 42, respectively communicating with the outlet of the heat exchange assembly and the outlet of the nitrogen flow channel 81 of the downstream gas-nitrogen-heat-conducting medium plate heat exchanger 8, nitrogen gas discharged separately after heat exchange between the condenser side and the freeze-drying chamber side is discharged, preventing interference between the gas circulations of the two refrigeration circuits and ensuring independent and smooth operation of the airflow within the system.

[0082] In addition, a temperature sensor 43 and a control valve 44 are provided on the first return air branch pipeline 41 and the second return air branch pipeline 42. The temperature sensor 43 can monitor the temperature of the two exhaust nitrogen in real time, thereby reflecting the heat exchange effect and cold capacity utilization of the condenser and the freeze-drying chamber. Based on the temperature monitoring data, the control valve 44 can accurately adjust the return air flow rate, so that when the nitrogen temperature on one side is abnormal (such as too high indicating that the cold capacity is not fully utilized, too low may mean that the liquid nitrogen supply is excessive), the opening of the control valve 44 can be adjusted, and the liquid nitrogen input can be optimized (increased or decreased), thereby achieving dynamic independent control of the two refrigeration circuits, improving the accuracy and stability of the system refrigeration, and avoiding energy waste.

[0083] In a further embodiment, the first heat transfer medium circulation loop 10 is provided with a balancing cylinder 101 , a circulation pump 102 and a heater 103 in sequence along the heat transfer medium circulation direction.

[0084] Among them, the balancing cylinder 101 is connected to the atmosphere. Since the length and volume of the pipeline are fixed, when the temperature of the silicone oil changes and causes its own volume to increase (i.e., expand), the closed pipeline will cause the silicone oil to be overpressured. Therefore, by connecting the balancing cylinder 101 to the atmospheric pressure, the liquid level of the silicone oil in the balancing cylinder 101 can be raised and lowered when it expands, so as to effectively avoid the occurrence of pipeline rupture or leakage caused by the expansion of the silicone oil.

[0085] The circulation pump 102 is used to provide power for the circulation of the heat transfer medium, ensuring that the medium after absorbing cold energy can be continuously transported to the freeze drying chamber body 1 to meet its refrigeration needs.

[0086] The heater 103 is used to perform micro-heating adjustment on the heat-conducting medium according to the precise temperature requirements of the freeze-drying process, to compensate for possible overcooling, and thus to ensure precise control of the temperature inside the freeze-drying chamber body 1, so that the entire freeze-drying process is carried out in a stable temperature environment, thereby improving the quality consistency of the freeze-dried product.

[0087] In addition, the outlets of the plurality of first flow channels 51 are connected to the inlet of the heat exchange assembly through the first confluence pipe 511. By providing the first confluence pipe 511, the nitrogen flow entering the heat exchange assembly is ensured to be stable, avoiding the overall cooling effect affected by the output fluctuation of a single flow channel, and reducing the resistance loss caused by the dispersed pipeline, thereby improving the nitrogen delivery efficiency.

[0088] The outlets of the plurality of third flow channels 71 are connected to the nitrogen flow channel 81 of the upstream gas-nitrogen-heat-conducting medium plate heat exchanger 8 through the second confluence pipe 711 to ensure that the amount of nitrogen entering the gas-nitrogen-heat-conducting medium plate heat exchanger 8 is balanced and stable, thereby providing continuous and uniform cooling capacity for the heat-conducting medium in the heat-conducting medium flow channel 82.

[0089] Example 2

[0090] like Figure 2 As shown, the difference between this embodiment and the first embodiment is that the refrigeration load capacity and anti-power outage capability of the coil 21 are improved, so that the temperature control of the coil 21 is more precise, thereby improving the reproducibility of the freeze-drying system.

[0091] As shown below, a refrigeration system of a freeze dryer includes a freeze drying chamber body 1, a condenser body 2, two sets of refrigeration and heat exchange modules, a liquid nitrogen input pipeline 3 and a return air pipeline 4.

[0092] The condenser body 2 is connected to the freeze drying chamber body 1, and both the condenser body 2 and the freeze drying chamber body 1 have a second heat transfer medium circulation loop 11. It should be noted that the heat transfer medium in the second heat transfer medium circulation loop 11 is silicone oil.

[0093] Both sets of refrigeration and heat exchange modules include multiple sets of parallel plate heat exchanger bodies 12 and gas-nitrogen-heat-conducting medium plate heat exchangers 8, which are respectively used to cool and exchange heat with the condenser body 2 and the second heat-conducting medium circulation loop 11 of the freeze-drying chamber body 1. By providing two sets of refrigeration and heat exchange modules, respectively for cooling and exchanging heat with the condenser body 2 and the freeze-drying chamber body 1, the scalability of the freeze-drying system is improved through the same modular structure.

[0094] The plate heat exchanger body 12 has a fifth flow channel 121 for vaporizing liquid nitrogen and a sixth flow channel 122 for circulating nitrogen. Specifically, the fifth flow channel 121 vaporizes liquid nitrogen to produce low-temperature nitrogen, serving as a cooling source, while the sixth flow channel 122 serves as a nitrogen circulation channel, allowing the heat-exchanged nitrogen to circulate back for secondary heat exchange.

[0095] The inlet and outlet of the fifth flow channel 121 are respectively connected to the liquid nitrogen input pipeline 3 and the nitrogen flow channel 81 of the gas-nitrogen-heat-conducting medium plate heat exchanger 8. That is, the connection between the fifth flow channel 121, the liquid nitrogen input pipeline 3, and the nitrogen flow channel 81 of the gas-nitrogen-heat-conducting medium plate heat exchanger 8 forms a primary cooling energy delivery path of "liquid nitrogen input → vaporization to produce cooling energy → cooling energy transfer to the nitrogen flow channel 81," providing a low-temperature nitrogen source for subsequent heat exchange with the heat-conducting medium.

[0096] Specifically, multiple groups of nitrogen flow channels 81 of the gas-nitrogen-heat-conducting medium plate heat exchanger 8 are connected to the sixth flow channel 122, forming a third heat exchange loop 13. This third heat exchange loop 13 is used for multi-stage heat exchange with the fifth flow channel 121 and the heat-conducting medium flow channel 82 of the gas-nitrogen-heat-conducting medium plate heat exchanger 8. This allows nitrogen, after exchanging heat with the heat-conducting medium in the nitrogen flow channel 81, to flow back to the sixth flow channel 122 and exchange heat again with the new liquid nitrogen in the fifth flow channel 121, completing the cascade utilization of cold energy. This cycle extends the cold energy transfer path, improving the efficiency of liquid nitrogen utilization and, through multi-stage heat exchange, ensuring smoother cold energy transfer to the heat-conducting medium flow channel 82.

[0097] In addition, the heat transfer medium flow channels 82 of the multiple gas nitrogen-heat transfer medium plate heat exchangers 8 are connected to the second heat transfer medium circulation loop 11 to transport the heat transfer medium (such as silicone oil) that absorbs cold energy to the condenser body 2 and the freeze drying box body 1 respectively, thereby realizing indirect refrigeration. The indirect heat exchange method avoids the drastic temperature fluctuations caused by direct contact with liquid nitrogen, improves the refrigeration load capacity and anti-power outage capability of the coil 21, and can make the temperature control of the coil 21 more precise, thereby improving the reproducibility of the freeze drying system.

[0098] It should be noted that a connecting pipe 14 is provided between the two second heat transfer medium circulation loops 11 , a balancing cylinder 101 is provided on the connecting pipe 14 , and a circulation pump 102 is provided on both the second heat transfer medium circulation loops 11 .

[0099] It should be noted that when the coil 21 is flowing with silicone oil, the silicone oil systems of the freeze drying chamber body 1 and the condenser body 2 are independent of each other. Both circuits have a circulation pump 102, and the circuit of the freeze drying chamber body 1 is additionally provided with a heater 103, and share a set of balancing cylinders 101. Since the balancing cylinder 101 only serves to regulate the volume change of the silicone oil caused by sudden temperature changes, the temperatures of the two circuits will not affect each other.

[0100] This embodiment can effectively improve the refrigeration load capacity of the coil 21 through the collaborative design of "independent dual-module refrigeration + multi-stage cascade heat exchange + silicone oil medium circulation", and enhance the temperature stability during power outages through closed-loop circulation and energy storage medium, and improve the temperature control accuracy through multi-stage buffer heat exchange and independent adjustment mechanism, thereby significantly improving the operating stability and process repeatability of the freeze-drying system, providing more reliable technical support for high-requirement freeze-drying scenarios (such as medicines and biological products).

[0101] Example 3

[0102] This embodiment proposes a heat exchange method for a freeze dryer, which is applied to the refrigeration system of the freeze dryer described in Example 1, including a multi-stage heat exchange method on the condenser side and a multi-stage heat exchange method on the freeze drying chamber side;

[0103] The multi-stage heat exchange method on the condenser side includes the following steps:

[0104] S1, liquid nitrogen enters the first flow channel 51 of the plurality of first plate heat exchangers 5 through the liquid nitrogen input pipeline 3, absorbs heat and vaporizes to form nitrogen gas, and then converges and enters the inlet of the heat exchange component;

[0105] S2, nitrogen flows through the upstream coil 21 of the heat exchange assembly and exchanges heat with the water vapor in the condenser body 2. The nitrogen then flows back to the second flow channel 52 of the first plate heat exchanger 5 to exchange heat with the liquid nitrogen in the first flow channel 51. After the heat exchange is completed, the nitrogen flows into the next coil 21 to exchange heat with the water vapor in the condenser body 2 again, thereby forming a first heat exchange loop 6 that performs multi-stage alternating heat exchange with the first flow channel 51 and the water vapor in the condenser body 2.

[0106] S3. After the nitrogen passes through the multiple groups of coils 21, the nitrogen is discharged from the outlet of the downstream coil 21 through the return air pipeline 4.

[0107] That is, during the refrigeration process of condenser body 2, the nitrogen generated by vaporizing liquid nitrogen in first flow channel 51 first exchanges heat with water vapor in upstream coil 21, then flows back to second flow channel 52 to exchange heat with new liquid nitrogen, and then enters the next coil 21 to repeat the heat exchange. This formed first heat exchange loop 6 allows nitrogen to undergo multi-stage alternating heat exchange with liquid nitrogen and water vapor. This process extends the release path of nitrogen cooling capacity, avoiding the problem of underutilized cooling capacity after a single heat exchange and subsequent discharge. This not only improves the utilization rate of liquid nitrogen cooling capacity, but also buffers temperature fluctuations through multiple heat exchanges, ensuring more uniform condensation and ice capture of water vapor in condenser body 2.

[0108] The multi-stage heat exchange method on the freeze drying chamber side comprises the following steps:

[0109] T1, liquid nitrogen enters the third flow channel 71 of the second plate heat exchanger 7 through the liquid nitrogen input pipeline 3, absorbs heat and vaporizes to form nitrogen gas, and then merges and enters the nitrogen flow channel 81 of the upstream gas nitrogen-heat transfer medium plate heat exchanger 8;

[0110] T2, the nitrogen in the nitrogen flow channel 81 exchanges heat with the heat-conducting medium in the heat-conducting medium flow channel 82, and then flows back to the fourth flow channel 72 of the second plate heat exchanger 7, exchanges heat with the liquid nitrogen in the third flow channel 71, and after completing the heat exchange, flows into the nitrogen flow channel 81 of the next-stage gas nitrogen-heat-conducting medium plate heat exchanger 8, thereby forming a second heat exchange loop 9 that performs multi-stage alternating heat exchange with the third flow channel 71 and the first heat-conducting medium circulation loop 10;

[0111] T3. After the nitrogen flows through multiple groups of gas nitrogen-heat conducting medium plate heat exchangers 8 in sequence, it is discharged from the nitrogen flow channel 81 outlet of the downstream gas nitrogen-heat conducting medium plate heat exchanger 8 through the return air pipeline 4. At the same time, the heat conducting medium cools the freeze drying chamber body 1 through the first heat conducting medium circulation loop 10.

[0112] That is, during the refrigeration process of the freeze-drying chamber body 1, the nitrogen gas after vaporization in the third flow channel 71 first exchanges heat with the heat-conducting medium in the heat-conducting medium flow channel 82, then flows back to the fourth flow channel 72 to exchange heat with the new liquid nitrogen, and then enters the next-stage gas nitrogen-heat-conducting medium plate heat exchanger 8, forming a second heat exchange loop 9 to achieve multi-stage heat exchange between nitrogen, liquid nitrogen, and the heat-conducting medium. This design allows the heat-conducting medium to continuously absorb sufficient cold energy when cooling the freeze-drying chamber body 1 through the first heat-conducting medium circulation loop 10, ensuring the stability of the freeze-drying chamber refrigeration temperature, while reducing liquid nitrogen consumption and improving energy utilization efficiency.

[0113] That is, in the above-mentioned heat exchange process, by adopting the "gasification-heat exchange-reflux-reheat exchange" cycle mode to form a multi-stage heat exchange function, the cold energy is released step by step and utilized step by step during the transmission process, which not only reduces the waste of cold energy, but also balances the temperature fluctuations through multiple heat exchanges, providing stable and efficient cold energy support for the ice capture of the condenser body 2 and the refrigeration of the freeze-drying box body 1.

[0114] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A refrigeration system for a freeze dryer, characterized in that: It comprises a freeze drying chamber body (1), a condenser body (2), a condenser refrigeration and heat exchange module, a freeze drying chamber refrigeration and heat exchange module, a liquid nitrogen input pipeline (3) and a return air pipeline (4); The condenser body (2) is in communication with the freeze drying chamber body (1) and is equipped with a heat exchange component for condensing water vapor; The condenser refrigeration and heat exchange module is in communication with the liquid nitrogen input pipeline (3) and the inlet of the heat exchange component, and is used for performing multi-stage heat exchange on the condenser body (2); The freeze drying box refrigeration and heat exchange module is in communication with the liquid nitrogen input pipeline (3) and is used for performing multi-stage heat exchange on the freeze drying box body (1); The return air pipeline (4) is in communication with the outlet of the heat exchange component and the outlet of the freeze-drying box refrigeration and heat exchange module.

2. The refrigeration system of the freeze dryer according to claim 1, characterized in that The condenser refrigeration and heat exchange module comprises a plurality of first plate heat exchangers (5) arranged in parallel; The first plate heat exchanger (5) has a first flow channel (51) for gasifying liquid nitrogen and a second flow channel (52) for circulating nitrogen; The inlets and outlets of the plurality of first flow channels (51) are respectively connected to the liquid nitrogen input pipeline (3) and the inlet of the heat exchange component; wherein the outlets of the plurality of first flow channels (51) are connected to the inlet of the heat exchange component via a first confluence pipe (511); Both ends of the plurality of second flow channels (52) are connected to the heat exchange component to form a first heat exchange circuit (6), and the first heat exchange circuit (6) is used to perform multi-stage heat exchange with the first flow channel (51).

3. The refrigeration system of the freeze dryer according to claim 2, characterized in that: The heat exchange assembly comprises a plurality of coils (21) arranged in series; The outlets and inlets of two adjacent groups of coils (21) are respectively connected to the same second flow channel (52) through a pipeline to form the first heat exchange circuit (6); The inlet of the coil (21) located upstream is communicated with the output end of the first plate heat exchanger (5), and the outlet of the coil (21) located downstream is communicated with the return air pipeline (4); The ratio of the number of the first plate heat exchangers (5) to the number of the coils (21) is N:N+1.

4. The refrigeration system of the freeze dryer according to claim 1, characterized in that The freeze-drying box refrigeration and heat exchange module includes multiple sets of second plate heat exchangers (7) and gas nitrogen-heat conducting medium plate heat exchangers (8) arranged in parallel; The second plate heat exchanger (7) has a third flow channel (71) for gasifying liquid nitrogen and a fourth flow channel (72) for circulating nitrogen; The inlets and outlets of the plurality of third flow channels (71) are respectively connected to the liquid nitrogen input pipeline (3) and the nitrogen flow channel (81) of the upstream gas nitrogen-heat conducting medium plate heat exchanger (8); The outlets of the plurality of third flow channels (71) are connected to the nitrogen flow channel (81) of the upstream nitrogen-heat-conducting medium plate heat exchanger (8) through a second converging pipe (711); A plurality of nitrogen flow channels (81) of the gas-nitrogen-heat-conducting medium plate heat exchanger (8) are in communication with the fourth flow channel (72) to form a second heat exchange circuit (9), the second heat exchange circuit (9) being used for performing multi-stage heat exchange with the third flow channel (71) and the heat-conducting medium flow channel (82) of the gas-nitrogen-heat-conducting medium plate heat exchanger (8); Wherein, a first heat-conducting medium circulation loop (10) is connected between the heat-conducting medium flow channel (82) of the gas-nitrogen-heat-conducting medium plate heat exchanger (8) and the freeze-drying chamber body (1); The return air pipeline (4) is in communication with the outlet of the heat exchange component and the outlet of the nitrogen flow channel (81) of the downstream nitrogen-heat-conducting medium plate heat exchanger (8).

5. The refrigeration system of the freeze dryer according to claim 4, characterized in that: The return air pipeline (4) comprises a first return air branch pipeline (41) communicating with the outlet of the heat exchange component and a second return air branch pipeline (42) communicating with the outlet of the nitrogen flow channel (81) of the downstream gas nitrogen-heat conducting medium plate heat exchanger (8); The first return air branch pipeline (41) and the second return air branch pipeline (42) are both provided with a temperature sensor (43) and a control valve (44).

6. The refrigeration system of the freeze dryer according to claim 4, characterized in that: The ratio of the number of the second plate heat exchangers (7) to the number of the gas nitrogen-heat conducting medium plate heat exchangers (8) is N:N+1.

7. The refrigeration system of the freeze dryer according to claim 4, characterized in that: The first heat-conducting medium circulation loop (10) is provided with a balancing cylinder (101), a circulation pump (102) and a heater (103) in sequence along the heat-conducting medium circulation direction.

8. A refrigeration system for a freeze dryer, characterized in that: It comprises a freeze-drying box body (1), a condenser body (2), two sets of refrigeration and heat exchange modules, a liquid nitrogen input pipeline (3) and a return air pipeline (4); The condenser body (2) is in communication with the freeze drying chamber body (1), and both the condenser body (2) and the freeze drying chamber body (1) have a second heat transfer medium circulation loop (11); The two groups of refrigeration and heat exchange modules each include a plurality of plate heat exchanger bodies (12) and gas nitrogen-heat-conducting medium plate heat exchangers (8) arranged in parallel, which are used to perform refrigeration and heat exchange on the condenser body (2) and the second heat-conducting medium circulation circuit (11) of the freeze-drying box body (1), respectively; The plate heat exchanger body (12) has a fifth flow channel (121) for gasifying liquid nitrogen and a sixth flow channel (122) for circulating nitrogen; The inlet and outlet of the fifth flow channel (121) are respectively connected to the liquid nitrogen input pipeline (3) and the nitrogen flow channel (81) of the gas nitrogen-heat conducting medium plate heat exchanger (8); A plurality of nitrogen flow channels (81) of the gas-nitrogen-heat-conducting medium plate heat exchanger (8) are in communication with the sixth flow channel (122) to form a third heat exchange circuit (13), wherein the third heat exchange circuit (13) is used for performing multi-stage heat exchange with the fifth flow channel (121) and the heat-conducting medium flow channel (82) of the gas-nitrogen-heat-conducting medium plate heat exchanger (8); The heat transfer medium flow channels (82) of the plurality of gas-nitrogen-heat transfer medium plate heat exchangers (8) are in communication with the second heat transfer medium circulation circuit (11).

9. The refrigeration system of the freeze dryer according to claim 8, characterized in that: A connecting pipe (14) is provided between the two second heat-conducting medium circulation loops (11), and a balancing cylinder (101) is provided on the connecting pipe (14); A circulation pump (102) is provided on each of the two second heat-conducting medium circulation loops (11).

10. A heat exchange method for a freeze dryer, applied to the refrigeration system of the freeze dryer according to claims 1-7, characterized in that: It includes a multi-stage heat exchange method on the condenser side and a multi-stage heat exchange method on the freeze drying chamber side; The multi-stage heat exchange method on the condenser side includes the following steps: S1, liquid nitrogen enters the first flow channel (51) of the plurality of first plate heat exchangers (5) through the liquid nitrogen input pipeline (3), absorbs heat and vaporizes to form nitrogen gas, and then flows into the inlet of the heat exchange component after converging; S2, nitrogen flows through the upstream coil (21) of the heat exchange component and exchanges heat with the water vapor in the condenser body (2), then flows back to the second flow channel (52) of the first plate heat exchanger (5), exchanges heat with the liquid nitrogen in the first flow channel (51), and after completing the heat exchange, flows into the next coil (21) to exchange heat with the water vapor in the condenser body (2) again, thereby forming a first heat exchange circuit (6) that performs multi-stage alternating heat exchange with the first flow channel (51) and the water vapor in the condenser body (2); S3. After the nitrogen passes through the multiple coils (21), the nitrogen is discharged from the outlet of the downstream coil (21) through the return air line (4); The multi-stage heat exchange method on the freeze drying chamber side comprises the following steps: T1, liquid nitrogen enters the third flow channel (71) of the second plate heat exchanger (7) through the liquid nitrogen input pipeline (3), absorbs heat and vaporizes to form nitrogen gas, and then merges and enters the nitrogen flow channel (81) of the upstream gas nitrogen-heat conducting medium plate heat exchanger (8); After the nitrogen in the nitrogen flow channel (81) exchanges heat with the heat-conducting medium in the heat-conducting medium flow channel (82), the nitrogen flows back to the fourth flow channel (72) of the second plate heat exchanger (7) to exchange heat with the liquid nitrogen in the third flow channel (71). After the heat exchange is completed, the nitrogen flows into the nitrogen flow channel (81) of the next-stage gas nitrogen-heat-conducting medium plate heat exchanger (8), thereby forming a second heat exchange circuit (9) that performs multi-stage alternating heat exchange with the third flow channel (71) and the first heat-conducting medium circulation circuit (10); T3. After the nitrogen flows through the multiple groups of gas nitrogen-heat conducting medium plate type heat exchangers (8) in sequence, it is discharged from the nitrogen flow channel (81) outlet of the downstream gas nitrogen-heat conducting medium plate type heat exchanger (8) through the return air pipeline (4), while the heat conducting medium cools the freeze drying chamber body (1) through the first heat conducting medium circulation loop (10).

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