Total reflux hydrogen isotope rectification separation device and method

Abstract

The invention discloses a total reflux hydrogen isotope rectification separation device which comprises a rectification tower and a refrigeration system, the refrigerating system comprises a normal-temperature compressor, a compressor cooler, a regenerative heat exchanger and a low-temperature expansion machine; the normal-temperature compressor is connected with the compressor cooler, the compressor cooler is connected with the regenerative heat exchanger, the regenerative heat exchanger is connected with the low-temperature expansion machine, and the outlet end of the low-temperature expansion machine enters the condenser through a pipeline, then returns to the regenerative heat exchanger and then returns to the normal-temperature compressor; one end of the parallel pipeline is connected between the condenser and the regenerative heat exchanger, and the other end of the parallel pipeline is connected between the regenerative heat exchanger and the low-temperature expansion machine; the low-temperature compressor is connected to the parallel pipeline and located at the inlet end of the reboiler. The invention also discloses a total reflux hydrogen isotope rectification separation method. The reboiler has the beneficial effects that no extra heat source is needed for heating the reboiler, heat exchange loss of the heat regenerator is avoided, and the low-temperature pressurizing efficiency is higher.

Description

Technical Field

[0001] The invention relates to the field of refrigeration and cryogenic engineering, and in particular to a full reflux hydrogen isotope distillation separation device and method. Background Art

[0002] A hydrogen isotope cryogenic distillation tower is a device that uses the slight difference in boiling point of hydrogen isotope components at the same pressure for separation and purification. During use, the hydrogen isotope cryogenic distillation tower needs to provide cooling capacity to the condenser for the continuous liquefaction of the gas components at the top of the tower, and heat to the reboiler for the continuous vaporization of the liquid at the bottom of the tower. The components liquefied by the condenser have a lower temperature and flow downward, and the components vaporized by the reboiler have a higher temperature and flow upward. The gas phase and the liquid phase perform mass transfer and heat transfer during the up and down flow process to achieve the separation of the components, thereby obtaining the separation and concentration effect of different isotope components. For example, CN114383383A-A hydrogen isotope cryogenic distillation purification device and method, the full reflux distillation method is a separation method that can be regarded as having an infinite number of tower plates. It has a wide range of applications in the field of isotope separation with extremely small differences in component boiling points, and can achieve efficient isotope separation and concentration.

[0003] In the traditional hydrogen isotope distillation tower, an independent refrigeration system needs to be designed to provide a cold source for the condenser during full reflux distillation. At the same time, an independent heating system (usually heated by an electric heater) needs to be designed to provide heat for the reboiler. The refrigeration system usually adopts throttling, expansion or a combination of the two to achieve refrigeration. Regardless of the method, the refrigerant needs to be pressurized, and the pressurization process is generally carried out at room temperature. The compression heat is taken away by the room temperature cooler and cannot be used. In addition, a heat recovery heat exchanger is required between low temperature and room temperature, resulting in serious heat exchange losses, low system efficiency and poor economy.

[0004] The information disclosed in this background technology section is only intended to enhance the understanding of the overall background of the invention and should not be regarded as an acknowledgment or any form of suggestion that the information constitutes the prior art known to a person skilled in the art. Summary of the invention

[0005] The technical problem to be solved by the present invention is: how to solve the problem that the current refrigeration pressurization process is carried out at room temperature, the compression heat is taken away by the room temperature cooler, and the heat exchange loss is serious.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A full reflux hydrogen isotope distillation separation device comprises a distillation tower and a refrigeration system; the top and bottom of the distillation tower are respectively connected to a condenser and a reboiler; the refrigeration system comprises a normal temperature compressor, a compressor cooler, a regenerative heat exchanger, and a low temperature expander; the normal temperature compressor is connected to the compressor cooler, the compressor cooler is connected to the regenerative heat exchanger, the regenerative heat exchanger is connected to the low temperature expander, and the outlet end of the low temperature expander enters the condenser through a pipeline, then returns to the regenerative heat exchanger, and then returns to the normal temperature compressor;

[0008] The refrigeration system also includes a parallel pipeline and a low-temperature compressor. One end of the parallel pipeline is connected between the condenser and the heat recovery heat exchanger, and the other end is connected between the heat recovery heat exchanger and the low-temperature expander. The low-temperature compressor is connected to the parallel pipeline and is located at the inlet end of the reboiler.

[0009] In the liquefaction process of the present invention, a normal temperature compressor, a compressor cooler, a regenerative heat exchanger, and a low-temperature expander are used to provide cooling capacity for the condenser; in the process of stable operation of full reflux distillation, when the liquid level accumulates to a certain level, a part of the low-temperature helium coming out of the condenser after heat exchange is directly sent to the reboiler after being compressed by the low-temperature compressor, and the compression heat is used as a heat source for heating the reboiler of the distillation tower, and the other part of the low-temperature helium enters the regenerative heat exchanger; the high-pressure low-temperature helium after heat exchange and the high-pressure low-temperature helium after compression by the low-temperature compressor are combined and then enter the low-temperature expander for expansion to obtain helium at a lower temperature; the helium at a lower temperature enters the condenser for heat exchange, and finally forms a closed refrigeration cycle, realizing the stable operation of full reflux distillation of the distillation tower. In the present invention, in the process of full reflux distillation, the gas at the outlet of the low-temperature compressor directly heats the liquid in the reboiler, and no additional heat source is required for heating the reboiler. This part of the helium does not need to be heated back to room temperature for compression, and there is no heat exchange loss in the regenerator, and the low-temperature boosting efficiency is higher.

[0010] Preferably, the compressor cooler is connected to the high-temperature side of the heat exchanger, the heat exchanger is connected to the low-temperature expander, the outlet end of the low-temperature expander enters the condenser through a pipeline and then returns to the low-temperature side of the heat exchanger, and then returns to the normal temperature compressor.

[0011] Preferably, it also includes a low-temperature compressor bypass valve, which is connected to the parallel pipeline and located at the outlet end of the reboiler.

[0012] Preferably, a reflux tank is further included, and one end of the reflux tank is connected to the condenser.

[0013] Preferably, the bottom of the reflux tank is connected to a tower top product discharge valve.

[0014] Preferably, the tower bottom product discharge valve is further included, and the tower bottom product discharge valve is connected to the bottom of the reboiler.

[0015] Preferably, it also includes an air intake valve, which is connected to the middle part of the distillation tower.

[0016] Preferably, it also includes a shell, wherein the distillation tower, the condenser, the reboiler, the heat recovery heat exchanger, the low-temperature expander, the parallel pipeline, and the low-temperature compressor are all located in the shell, and the normal temperature compressor and the compressor cooler are located outside the shell.

[0017] Preferably, the working fluid in the refrigeration system is helium.

[0018] The present invention also discloses a total reflux hydrogen isotope distillation separation method, which uses the total reflux hydrogen isotope distillation separation device.

[0019] During the liquefaction process, the raw gas enters the distillation tower; the normal temperature compressor pressurizes the helium and then cools it to room temperature through the compressor cooler. The high-pressure gas enters the high-temperature side of the regenerative heat exchanger to exchange heat with the low-temperature helium in the reflux low-temperature side. The low-temperature helium after heat exchange enters the low-temperature expander, and obtains helium at a lower temperature after passing through the low-temperature expander. The helium at a lower temperature enters the condenser for heat exchange, and the cold energy is transferred to the condenser to cool and liquefy the raw gas entering the distillation tower. The low-temperature helium after heat exchange enters the low-temperature side of the regenerative heat exchanger to exchange heat with the high-temperature helium in the high-temperature side. The helium that has returned to room temperature then enters the normal temperature compressor for pressurization, forming a closed refrigeration cycle, and the raw gas is liquefied and liquid is gradually accumulated;

[0020] During the stable operation of full reflux distillation, when the liquid level accumulates to a certain level, the raw gas stops intake, the cryogenic compressor is turned on, and part of the cryogenic helium coming out of the condenser after heat exchange is compressed by the cryogenic compressor and directly sent to the reboiler, and the other part of the cryogenic helium enters the low-temperature side of the regenerative heat exchanger for heat recovery and then enters the normal temperature compressor for compression. The pressurized helium is cooled to room temperature by the compressor cooler, and then enters the high-temperature side of the regenerative heat exchanger for heat exchange with the cryogenic helium in the reflux low-temperature side; the high-pressure low-temperature helium after heat exchange and the high-pressure low-temperature helium after compression by the cryogenic compressor are combined and enter the cryogenic expander for expansion to obtain helium at a lower temperature; the helium at a lower temperature enters the condenser for heat exchange, and finally forms a closed refrigeration cycle.

[0021] The advantages of the present invention are:

[0022] In the liquefaction process of the present invention, a normal temperature compressor, a compressor cooler, a regenerative heat exchanger and a low-temperature expander are used to provide cooling capacity for the condenser; in the process of stable operation of full reflux distillation, when the liquid level accumulates to a certain level, a part of the low-temperature helium coming out of the condenser after heat exchange is compressed by the low-temperature compressor and directly sent to the reboiler, and the compression heat is used as a heat source to heat the reboiler of the distillation tower, and the other part of the low-temperature helium enters the regenerative heat exchanger; the high-pressure low-temperature helium after heat exchange and the high-pressure low-temperature helium after compression by the low-temperature compressor are combined and enter the low-temperature expander for expansion to obtain helium at a lower temperature; the helium at a lower temperature enters the condenser for heat exchange, and finally forms a closed refrigeration cycle, so as to realize the stable operation of full reflux distillation of the distillation tower.

[0023] In order to solve the problems that the compression heat in traditional hydrogen isotope distillation cannot be utilized and the heat exchange loss of the regenerator is serious, the present invention uses a low-temperature compressor to replace the traditional normal temperature compression and heat exchanger. The gas at its outlet directly heats the liquid in the reboiler without the need for an additional heat source, thus avoiding the heat exchange loss of the regenerator and improving the low-temperature pressurization efficiency.

[0024] The low-temperature gas at the outlet of the low-temperature expander directly provides cooling for the condenser. The raw gas inlet to the distillation tower does not require an additional cooling source, and the gas can directly enter the distillation tower.

[0025] Both the low-temperature compressor and the normal-temperature compressor are frequency-controlled, and the distillation tower and refrigeration system realize self-coupling of the cold source and the heat source, making the entire distillation system more energy-efficient and economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 2 is a schematic structural diagram of a full reflux hydrogen isotope fractionation and separation device according to an embodiment of the present invention;

[0027] Numbers in the figure:

[0028] 1. Distillation tower; 11. Condenser; 12. Reboiler; 13. Reflux tank; 14. Top product discharge valve; 15. Bottom product discharge valve; 16. Air inlet valve;

[0029] 2. Refrigeration system; 21. Normal temperature compressor; 22. Compressor cooler; 23. Regenerative heat exchanger; 231. High temperature side; 232. Low temperature measurement; 24. Low temperature expander; 25. Low temperature compressor; 26. Low temperature compressor bypass valve;

[0030] 3. Shell. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] Embodiment 1:

[0033] like Figure 1 As shown, the full reflux hydrogen isotope distillation separation device includes a distillation tower 1, a refrigeration system 2 (not shown in the figure), and a shell 3. The refrigeration system 2 forms a closed loop connection with the distillation tower 1, and parts of the distillation tower 1 and the refrigeration system 2 are located in the shell 3.

[0034] Specifically, the top of the distillation tower 1 is connected to the condenser 11, and the bottom of the distillation tower 1 is connected to the reboiler 12; the distillation tower 1 is a typical distillation equipment, and the distillation tower 1 is the core equipment for realizing the distillation process, in which the vapor and liquid two phases are in contact for phase mass transfer. The function of the reboiler 12 is to partially evaporate the liquid, and the generated vapor rises along the tower, providing a certain amount of continuous rising vapor gas flow for the distillation operation. The condenser 11 realizes the condensation of the steam at the top of the tower, and part of the condensate is returned to the distillation tower 1 from the top of the tower as reflux liquid, and the remaining distillate is the top product of the tower.

[0035] In this embodiment, the distillation tower 1 further includes a reflux tank 13, one end of which is connected to the condenser 11, and the other end is provided with a tower top product discharge valve 14, which can extract qualified products after the products meet the purity requirements. The reflux tank 13 is used to collect the condensed liquid, a part of which is used as the tower top product (also called distillate), and the other part is sent into the tower as reflux liquid.

[0036] In this embodiment, the bottom of the reboiler 12 is connected to a bottom product discharge valve 15 for extracting a liquid product of a qualified purity.

[0037] In this embodiment, the distillation tower 1 is provided with an air inlet valve 16, and the air inlet valve 16 is arranged in the middle of the distillation tower 1. The feed is added in the middle of the tower, and the liquid in the feed descends along the tower together with the liquid from the upper tower section, and the steam in the feed rises along the tower together with the steam from the lower tower section.

[0038] The refrigeration system 2 includes a normal temperature compressor 21, a compressor cooler 22, a regenerative heat exchanger 23, a low temperature expander 24, and a low temperature compressor 25; the normal temperature compressor 21 is connected to the compressor cooler 22, the compressor cooler 22 is connected to the high temperature side 231 of the regenerative heat exchanger 23, the high temperature side 231 is connected to the low temperature expander 24, the outlet end of the low temperature expander 24 enters the condenser 11 through a pipeline, the pipeline coming out of the condenser 11 is connected to the low temperature side 232 of the regenerative heat exchanger 23, and the outlet end of the low temperature side 232 is connected to the normal temperature compressor 21 through a pipeline. A low temperature compressor 25 is connected in parallel to the pipeline between the condenser 11 and the low temperature side 232 of the regenerative heat exchanger 23, the outlet end of the low temperature compressor 25 enters the reboiler 12 through a pipeline for heat exchange, and then is connected to the pipeline between the low temperature expander 24 and the high temperature side 231 of the regenerative heat exchanger 23 through a pipeline.

[0039] A low-temperature compressor bypass valve 26 is also connected to the pipeline returning from the reboiler 12 to the low-temperature expander 24.

[0040] The working medium in the refrigeration system 2 of this embodiment is helium. Only the normal temperature compressor 21 and the compressor cooler 22 are located outside the shell 3, and the distillation tower 1 and the rest of the refrigeration system 2 are located inside the shell 3.

[0041] The liquefaction process workflow of this embodiment is as follows:

[0042] During the liquefaction process, the raw gas is fed, the intake valve 16 of the distillation tower 1 is opened, the low-temperature compressor bypass valve 26 is closed, the tower top product discharge valve 14 is closed, and the tower bottom product discharge valve 15 is closed; the normal temperature compressor 21 pressurizes the helium and then passes through the compressor cooler 22 to cool it to room temperature, and the high-pressure gas enters the high-temperature side 231 of the regenerative heat exchanger 23 to exchange heat with the low-temperature helium in the reflux low-temperature side 232, and the low-temperature helium after heat exchange enters the low-temperature expander 24, and obtains The helium at a lower temperature enters the condenser 11 for heat exchange, and the cold energy is transferred to the condenser 11 to cool and liquefy the raw gas entering the distillation tower 1. The low-temperature helium after heat exchange enters the low-temperature side 232 of the heat recovery heat exchanger 23 to exchange heat with the high-temperature helium in the high-temperature side 231, so as to recycle the cold energy of the helium. The helium that has returned to room temperature then enters the room-temperature compressor 21 for pressurization. The whole process is carried out continuously to form a closed refrigeration cycle, so as to realize the liquefaction of the raw gas and gradually accumulate the liquid.

[0043] The workflow of the stable operation process of total reflux distillation:

[0044] During the stable operation of the total reflux distillation, when the liquid level accumulates to a certain level, the feed gas stops entering, the intake valve 16 of the distillation tower 1 is closed, the cryogenic compressor 25 is opened, the cryogenic compressor bypass valve 26 is opened, the top product discharge valve 14 is kept closed, and the bottom product discharge valve 15 is kept closed; at this time, the cryogenic compressor 25 is frequency-up regulated, and the normal temperature compressor 21 is frequency-down regulated, and a part of the low-temperature helium coming out of the condenser 11 after heat exchange is compressed by the cryogenic compressor 25 and directly sent to the reboiler 12, and the compression heat is used as a heat source to heat the reboiler 12 of the distillation tower 1, and the other Part of the low-temperature helium enters the low-temperature side 232 of the regenerative heat exchanger 23 for heat recovery and then enters the normal temperature compressor 21 for compression. The pressurized helium is cooled to room temperature by the compressor cooler 22, and then enters the high-temperature side 231 of the regenerative heat exchanger 23 for heat exchange with the low-temperature helium in the reflux low-temperature side 232; the high-pressure low-temperature helium after heat exchange and the high-pressure low-temperature helium compressed by the low-temperature compressor 25 are combined and enter the low-temperature expander 4 for expansion to obtain helium at a lower temperature; the helium at a lower temperature enters the condenser 11 for heat exchange, and finally forms a closed refrigeration cycle, realizing the stable operation of the full reflux distillation of the distillation tower 1. The low-temperature compressor 25 and the normal temperature compressor 21 are adjusted by frequency conversion to achieve the matching of the heating demand of the reboiler 12 and the cooling demand of the condenser 11.

[0045] When the analysis confirms that the liquid purity in the reflux tank 13 and the reboiler 12 meets the requirements, the top product discharge valve 14 and the bottom product discharge valve 15 are opened respectively to extract liquid products of qualified purity from the top and bottom of the tower.

[0046] By alternating the liquefaction process and the full reflux distillation stable operation process, efficient full reflux hydrogen isotope distillation separation is ultimately achieved.

[0047] In this embodiment, in the full reflux distillation process, the gas at the outlet of the low-temperature compressor 25 directly heats the liquid in the reboiler 12, and no additional heat source is required for heating the reboiler 12. This part of helium does not need to be heated back to room temperature for compression, there is no heat exchange loss in the recuperator, and the low-temperature boosting efficiency is higher.

[0048] It should be noted that: Based on the ultra-low temperature and large pressure ratio working conditions in this field, suitable ultra-high speed motors, ultra-low temperature sealing elements, ultra-low friction or frictionless bearings and related advanced control algorithms and other technologies have been developed, which can support the low-temperature compressor in this application at the current technical level. This is also the condition for the first use of a low-temperature compressor in this embodiment. As for the above-mentioned technology, it is sufficient to use the currently developed ones, and this embodiment will not be described in detail.

[0049] The low-temperature gas at the outlet of the low-temperature expander 4 directly provides cooling capacity to the condenser 11 , and the raw gas inlet of the distillation tower 1 does not require an additional cooling source, and the gas can directly enter the distillation tower 1 .

[0050] Both the low-temperature compressor 25 and the normal-temperature compressor 21 are frequency-converted controlled, and the distillation tower 1 and the refrigeration system 2 realize self-coupling of the cold source and the heat source, so that the entire distillation system is more energy-efficient and economical.

[0051] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A full reflux hydrogen isotope distillation separation device, characterized in that: Including distillation tower and refrigeration system; The top and bottom of the distillation tower are connected to a condenser and a reboiler respectively; The refrigeration system comprises a normal temperature compressor, a compressor cooler, a regenerative heat exchanger, and a low temperature expander; the normal temperature compressor is connected to the compressor cooler, the compressor cooler is connected to the regenerative heat exchanger, the regenerative heat exchanger is connected to the low temperature expander, and the outlet of the low temperature expander enters the condenser through a pipeline, then returns to the regenerative heat exchanger, and then returns to the normal temperature compressor; The refrigeration system also includes a parallel pipeline and a low-temperature compressor. One end of the parallel pipeline is connected between the condenser and the heat recovery heat exchanger, and the other end is connected between the heat recovery heat exchanger and the low-temperature expander. The low-temperature compressor is connected to the parallel pipeline and is located at the inlet end of the reboiler.

2. The full reflux hydrogen isotope distillation separation device according to claim 1, characterized in that: The compressor cooler is connected to the high-temperature side of the heat exchanger, and the heat exchanger is connected to the low-temperature expander. The outlet end of the low-temperature expander enters the condenser through a pipeline and then returns to the low-temperature side of the heat exchanger, and then returns to the normal temperature compressor.

3. The full reflux hydrogen isotope distillation separation device according to claim 1, characterized in that: It also includes a low-temperature compressor bypass valve, which is connected to the parallel pipeline and is located at the outlet end of the reboiler.

4. The full reflux hydrogen isotope distillation separation device according to claim 1, characterized in that: It also includes a reflux tank, one end of which is connected to the condenser.

5. The full reflux hydrogen isotope distillation separation device according to claim 4, characterized in that: The bottom of the reflux tank is connected to the tower top product discharge valve.

6. The full reflux hydrogen isotope distillation separation device according to claim 1, characterized in that: The tower bottom product discharge valve is also included, and the tower bottom product discharge valve is connected to the bottom of the reboiler.

7. The full reflux hydrogen isotope distillation separation device according to claim 1, characterized in that: It also includes an air intake valve, which is connected to the middle part of the distillation tower.

8. The full reflux hydrogen isotope distillation separation device according to claim 1, characterized in that: It also includes a shell, wherein the distillation tower, the condenser, the reboiler, the heat recovery heat exchanger, the low-temperature expander, the parallel pipeline, and the low-temperature compressor are all located inside the shell, and the normal temperature compressor and the compressor cooler are located outside the shell.

9. The full reflux hydrogen isotope distillation separation device according to claim 1, characterized in that: The working medium in the refrigeration system is helium.

10. A total reflux hydrogen isotope distillation separation method, characterized in that: The full reflux hydrogen isotope distillation separation device according to any one of claims 1 to 8 above is used, During the liquefaction process, the raw gas enters the distillation tower; the normal temperature compressor pressurizes the helium and then cools it to room temperature through the compressor cooler. The high-pressure gas enters the high-temperature side of the regenerative heat exchanger to exchange heat with the low-temperature helium in the reflux low-temperature side. The low-temperature helium after heat exchange enters the low-temperature expander, and obtains helium at a lower temperature after passing through the low-temperature expander. The helium at a lower temperature enters the condenser for heat exchange, and the cold energy is transferred to the condenser to cool and liquefy the raw gas entering the distillation tower. The low-temperature helium after heat exchange enters the low-temperature side of the regenerative heat exchanger to exchange heat with the high-temperature helium in the high-temperature side. The helium that has returned to room temperature then enters the normal temperature compressor for pressurization, forming a closed refrigeration cycle, and the raw gas is liquefied and liquid is gradually accumulated; During the stable operation of full reflux distillation, when the liquid level accumulates to a certain level, the raw gas stops entering, the cryogenic compressor is turned on, and part of the cryogenic helium coming out of the condenser after heat exchange is compressed by the cryogenic compressor and directly sent to the reboiler, and the other part of the cryogenic helium enters the low-temperature side of the regenerative heat exchanger for heat recovery and then enters the normal temperature compressor for compression. The pressurized helium is cooled to room temperature by the compressor cooler, and then enters the high-temperature side of the regenerative heat exchanger for heat exchange with the cryogenic helium in the reflux low-temperature side; the high-pressure low-temperature helium after heat exchange and the high-pressure low-temperature helium after compression by the cryogenic compressor are combined and enter the cryogenic expander for expansion to obtain helium at a lower temperature; The helium at a lower temperature enters the condenser for heat exchange, eventually forming a closed refrigeration cycle.

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