Air separation system

Abstract

The invention provides an air separation system. The air separation system comprises a rectification device and a liquid nitrogen backup device. The liquid nitrogen backup device comprises a self-pressurization liquid storage unit, a vaporization unit and a normal-pressure liquid storage unit. The self-pressurization liquid storage unit is connected with the rectification device, and the normal-pressure liquid storage unit is connected with the rectification device through the self-pressurization liquid storage unit; the vaporization unit and the normal-pressure liquid storage unit are respectively connected with the self-pressurization liquid storage unit through a liquid supply pipeline; and the vaporization unit and the rectification device are communicated with a gas supply pipeline. Compared with the prior art, the self-pressurization liquid storage unit has at least one of the following beneficial effects that nitrogen can be automatically supplemented and supplied, the response speed is high, electricity consumption and liquid nitrogen loss are low, the pipe network pressure can be rapidly stabilized, waste of material discharge during pressure relief of the self-pressurization liquid storage unit is reduced, operation is convenient, and energy consumption and operation cost are reduced.

Description

Technical Field

[0001] This application relates to the technical field of air separation, and particularly to an air separation system. Background Art

[0002] The air separation technology principle of the air separation system is to separate components such as nitrogen, oxygen, and argon in the air, and use rectification technology to obtain various products. The products are mainly divided into two categories: gas and cryogenic liquid products, such as oxygen, nitrogen, argon, liquid oxygen, liquid nitrogen, liquid argon, etc. The most typical is to use an air separation nitrogen production system to obtain liquid nitrogen. Currently, the existing air separation nitrogen production systems usually configure a liquid nitrogen backup device so that when the air separation nitrogen production system stops or fails to provide nitrogen abnormally, the liquid nitrogen backup device can provide nitrogen to the pipeline network. On the premise of realizing the nitrogen supply guarantee ability, the existing liquid nitrogen backup devices mainly include the following two types: when the air separation nitrogen production system loses power, the liquid nitrogen is transported to the vaporizer by pressurizing with an emergency pump body for vaporization and then sent to the pipeline network; or without configuring an emergency pump body, the liquid nitrogen is transported to the vaporizer for vaporization and then sent to the pipeline network by utilizing the property that the self-pressurizing vacuum storage tank can also supply gas when powered off.

[0003] However, using an emergency pump body for nitrogen supply guarantee has problems such as a long nitrogen supply response time and pipeline network pressure loss. If the emergency pump body runs at a low speed for a long time to avoid the above problems, it will increase the adverse situations of additional energy consumption and equipment wear, and additionally configuring an emergency pump body also increases the cost. The existing technology uses a self-pressurizing liquid nitrogen storage tank for nitrogen supply guarantee, which will cause evaporation loss of liquid nitrogen and direct discharge resulting in waste, and the operation of replenishing liquid with a pump body is relatively frequent, which will increase equipment wear and cost.

[0004] Therefore, the air separation system in the existing technology still needs to be further improved. Summary of the Invention

[0005] Aiming at the deficiencies existing in the prior art, the purpose of the present invention is to provide an air separation system to at least alleviate or even solve at least one of the problems raised in the above background art to a certain extent.

[0006] In one aspect of the present invention, the present invention provides an air separation system, the air separation system includes a rectification device and a liquid nitrogen backup device, the liquid nitrogen backup device includes a self-pressurizing liquid storage unit, a vaporization unit, and an atmospheric pressure liquid storage unit; the self-pressurizing liquid storage unit is connected to the rectification device, and the atmospheric pressure liquid storage unit is connected to the rectification device through the self-pressurizing liquid storage unit; the vaporization unit and the atmospheric pressure liquid storage unit are respectively connected to the self-pressurizing liquid storage unit through a liquid supply pipeline; the vaporization unit and the rectification device are both connected to a gas supply pipeline.

[0007] Further, the air separation system further includes an exhaust pipeline, one end of the exhaust pipeline is connected to the top of the self-pressurizing liquid storage unit, and the other end is connected to at least one of the high-pressure side of the rectification device and the cold energy recovery device.

[0008] Further, the air separation system further includes an exhaust pipeline and a cold energy recovery device, one end of the exhaust pipeline is connected to the top of the self-pressurizing liquid storage unit, and the other end is connected to the cold energy recovery device.

[0009] Further, the liquid supply pipeline includes a first liquid supply pipeline, a second liquid supply pipeline, and a third liquid supply pipeline; the first liquid supply pipeline connects the high-pressure side of the rectification device and the top of the self-pressurizing liquid storage unit; the second liquid supply pipeline connects the bottom of the self-pressurizing liquid storage unit and the vaporization unit; the third liquid supply pipeline connects the bottom of the self-pressurizing liquid storage unit and the normal-pressure liquid storage unit.

[0010] Further, the liquid supply pipeline further includes a fourth liquid supply pipeline, the fourth liquid supply pipeline connects the normal-pressure liquid storage unit and the self-pressurizing liquid storage unit; and a first regulating valve and a pump body are provided on the fourth liquid supply pipeline.

[0011] Further, the liquid supply pipeline further includes a fifth liquid supply pipeline, the fifth liquid supply pipeline connects the bottom of the self-pressurizing liquid storage unit and the low-pressure side of the rectification device.

[0012] Further, the vaporization unit includes a gas outlet and a liquid inlet, and a first gas valve and a first pressure gauge are provided on the gas supply pipeline connected to one side of the gas outlet.

[0013] Further, the height of the self-pressurizing liquid storage unit is not higher than the height of the rectification device.

[0014] Further, the self-pressurizing liquid storage unit is connected with a second pressure gauge, a liquid level gauge, and a second gas valve; wherein, the second gas valve is located on the exhaust pipeline.

[0015] Further, a second regulating valve is provided on the second liquid supply pipeline.

[0016] Further, a third regulating valve is provided on the third liquid supply pipeline.

[0017] Further, a fourth regulating valve is provided on the fifth liquid supply pipeline.

[0018] In another aspect of the present invention, the present invention provides a method of using the above-mentioned air separation system, and the method includes: conveying liquid nitrogen from the high-pressure side of the rectification device to the self-pressurizing liquid storage unit via a first liquid supply pipeline; conveying the liquid nitrogen in the self-pressurizing liquid storage unit from the bottom to the vaporization unit to generate nitrogen gas, and / or conveying it to the atmospheric-pressure liquid storage unit for backup storage; supplying the nitrogen gas generated in the self-pressurizing liquid storage unit to the high-pressure side of the rectification device for recycling, and / or conveying it to a cold energy recovery device for cold energy recovery; supplying the nitrogen gas on the high-pressure side of the rectification device and the nitrogen gas generated by the vaporization unit to a gas supply pipeline.

[0019] Further, make the pressure difference between the top of the self-pressurizing liquid storage unit and the first liquid supply pipeline not higher than 0.1 MPAG; when the pressure value of the first pressure gauge decreases, open the first gas valve, so that the liquid nitrogen in the self-pressurizing liquid storage unit enters the vaporization unit for vaporization under the action of pressure, and is conveyed to the gas supply pipeline to maintain the stability of the pressure value of the first pressure gauge.

[0020] Further, open the third regulating valve to convey liquid nitrogen to the atmospheric-pressure liquid storage unit.

[0021] Further, keep the third regulating valve slightly open to maintain the liquid level balance in the atmospheric-pressure liquid storage unit.

[0022] Further, when a shutdown condition occurs, it further includes: conveying the liquid nitrogen in the atmospheric-pressure liquid storage unit to the inside of the self-pressurizing liquid storage unit, so as to vaporize the liquid nitrogen into nitrogen gas through the self-pressurizing liquid storage unit.

[0023] Further, when the air separation system is in a hot start state, it further includes: opening the fourth regulating valve to make the liquid nitrogen backflow into the low-pressure side of the rectification device.

[0024] The present invention has at least one of the following beneficial effects at least:

[0025] 1. For the air separation system of the present invention, a liquid nitrogen backup device in which liquid nitrogen first enters the self-pressurizing liquid storage unit and then enters the atmospheric-pressure liquid storage unit is adopted. When the network pressure drops abnormally, the liquid nitrogen backup device can automatically supply nitrogen gas for replenishment, with a fast response speed, low power consumption and liquid nitrogen loss, and can quickly and stably maintain the network pressure;

[0026] 2. For the air separation system of the present invention, the self-pressurizing liquid storage unit is interconnected with the gas and liquid phases of the rectification device, which can maintain the internal pressure balance of the self-pressurizing liquid storage unit, reduce the waste of material discharge during the pressure relief of the self-pressurizing liquid storage unit, and is convenient to operate;

[0027] 3. The air separation system of the present invention provides sufficient pressure and liquid level for the self-pressurizing liquid storage unit by reasonably configuring the material flow between each unit. It can still supply nitrogen externally when the factory power fails, without the need to install accident pump bodies and supporting accessories such as storage batteries and vaporizers, reducing related investments and saving costs.

[0028] 4. The air separation system of the present invention has a reasonable structure. For the liquid nitrogen consumption of the self-pressurizing liquid storage unit caused by short-term abnormalities, it can be directly supplemented by the device without starting the pump body. Only when the plant is shut down for a long time does the pump body need to be started, which can reduce the start-up times and duration of the pump body, reduce energy consumption, and reduce the wear and tear of the pump body.

[0029] 5. In the air separation system of the present invention, the liquid phase of the self-pressurizing liquid storage unit is connected to the low-pressure side of the rectification device through a liquid supply pipeline, which can realize the function of start-up reverse feeding, reduce the start-up time of the system, supply nitrogen externally in advance, and at the same time shorten the supply time of the liquid nitrogen backup device, reduce the overall energy consumption, and lower the operating cost.

[0030] 6. The air separation system of the present invention optimizes the configuration of the liquid nitrogen backup device at a relatively low cost, enhancing its usage function, facilitating operation, and reducing energy consumption.

[0031] The above summary is only for the purpose of the specification and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the present application will be readily apparent by reference to the drawings and the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In the drawings, unless otherwise specified, the same reference numerals throughout the several views denote the same or similar components or elements. These drawings are not necessarily drawn to scale. It should be understood that these drawings only depict some embodiments disclosed in the present application and should not be regarded as limiting the scope of the present application.

[0033] Figure 1 It is a schematic structural diagram of the air separation system according to an embodiment of the present invention;

[0034] Figure 2 It is a schematic structural diagram of an air separation system in the prior art;

[0035] Figure 3 It is a schematic structural diagram of another air separation system in the prior art;

[0036] Figure 4 It is a schematic structural diagram of the air separation system according to an embodiment of the present invention;

[0037] Figure 5 It is a schematic structural diagram of the air separation system according to an embodiment of the present invention;

[0038] Figure 6 Structural schematic diagram of an air separation system according to an embodiment of the present invention;

[0039] Figure 7 Structural schematic diagram of an air separation system according to an embodiment of the present invention.

[0040] Description of reference numerals: 1000 - Liquid nitrogen backup device, 2000 - Rectification device, 100 - Self - pressurizing liquid storage unit, 200 - Vaporization unit, 210 - Liquid inlet, 220 - Gas outlet, 300 - Atmospheric pressure liquid storage unit, 400 - Pump body, 400' - Emergency pump body, 500 - Uninterruptible power supply, 610 - First liquid supply pipeline, 620 - Second liquid supply pipeline, 630 - Third liquid supply pipeline, 640 - Fourth liquid supply pipeline, 650 - Fifth liquid supply pipeline, 700 - Gas supply pipeline, 800 - Exhaust pipeline, 900 - Safety pipeline, 11 - First gas valve, 12 - Second gas valve, 21 - First pressure gauge, 22 - Second pressure gauge, 23 - Third pressure gauge, 31 - Liquid level gauge, 41 - First regulating valve, 42 - Second regulating valve, 43 - Third regulating valve, 44 - Fourth regulating valve, 45 - Fifth regulating valve, 46 - Sixth regulating valve, 47 - Seventh regulating valve, 48 - Eighth regulating valve, 49 - Ninth regulating valve, 50 - Cold energy recovery device. Detailed implementation manners

[0041] In order to more clearly understand the technical features, objectives, and beneficial effects of the present invention, the technical solution of the present invention will now be further described in detail. In the following text, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present application. Therefore, the drawings and the description are considered to be exemplary in nature and not restrictive.

[0042] In one aspect of the present invention, the present invention provides an air separation system. Refer to Figure 1, the air separation system includes a rectification device 2000 and a liquid nitrogen backup device 1000. The rectification device 2000 is connected to the liquid nitrogen backup device 1000, and the liquid nitrogen backup device 1000 includes a self-pressurizing liquid storage unit 100, a vaporization unit 200, and an atmospheric pressure liquid storage unit 300. Among them, the liquid nitrogen backup device 1000 is connected to the rectification device 2000 through the self-pressurizing liquid storage unit 100, and the atmospheric pressure liquid storage unit 300 is indirectly connected to the rectification device 2000 through the self-pressurizing liquid storage unit 100. The vaporization unit 200 and the atmospheric pressure liquid storage unit 300 are respectively connected to the self-pressurizing liquid storage unit 100 through a liquid supply pipeline. The vaporization unit 200 and the rectification device 2000 are both connected to a gas supply pipeline 700. The air separation system has at least one of the following beneficial effects: it can automatically supply nitrogen, has a fast response speed, low power consumption and liquid nitrogen loss, can quickly and stably maintain the pipeline pressure, reduce the waste of material discharge when the self-pressurizing liquid storage unit 100 relieves pressure, is easy to operate, and reduces energy consumption and operating costs.

[0043] For the convenience of understanding, the principle by which the air separation system can achieve the above beneficial effects will be briefly described below:

[0044] As described above, the existing liquid nitrogen backup device 1000 mainly includes two types. Specifically, referring to Figure 2 , it shows the structural diagram of the first type of liquid nitrogen backup device 1000 in the prior art. The liquid nitrogen backup device 1000 mainly includes an atmospheric pressure liquid storage unit 300, a pump body 400, an emergency pump body 400', a vaporization unit 200, and an uninterruptible power supply (UPS) 500. The atmospheric pressure liquid storage unit 300 is a conventional configuration with a large storage capacity but a low working pressure, and a pump body 400 must be added for auxiliary use. Among them, the rectification device 2000 is directly connected to the atmospheric pressure liquid storage unit 300. The bottom of the atmospheric pressure liquid storage unit 300 is respectively connected to the pump body 400 and the emergency pump body 400'. The pump body 400 and the emergency pump body 400' are respectively connected to a separate vaporization unit 200, and the emergency pump body 400' is powered by the uninterruptible power supply 500. More specifically, under normal circumstances, the liquid nitrogen in the rectification device 2000 is sent to the atmospheric pressure liquid storage unit 300 under pressure, and then is pressurized by the pump body 400 and vaporized by the vaporization unit 200 and then sent to the pipeline network. When the system power fails, the liquid nitrogen is pressurized by the emergency pump body 400' and vaporized by the vaporization unit 200 and then sent to the pipeline network. However, when the nitrogen in the air separation system is interrupted and the first type of liquid nitrogen backup device 1000 is activated, it takes a certain amount of time for the emergency pump body 400' to go from preparation to start-up and then to send out nitrogen, resulting in problems such as a long nitrogen supply response time and pipeline network pressure loss. If you want to avoid this situation, you have to make the emergency pump body 400' run at a low speed for a long time to make up for it, which will increase the additional energy consumption and equipment wear. In addition, for the system power failure, an additional emergency nitrogen unit (such as the emergency pump body 400') is configured, increasing a certain investment cost. In addition, referring toFigure 3 , which shows the structural diagram of the second liquid nitrogen backup device 1000 in the prior art. The liquid nitrogen backup device 1000 includes an atmospheric pressure liquid storage unit 300, a self-pressurizing liquid storage unit 100, a pump body 400, and a vaporization unit 200. The self-pressurizing liquid storage unit 100 is generally an optional component with a relatively small storage capacity but has a certain working pressure and does not require the assistance of the pump body 400. Among them, the rectification device 2000 is connected to the atmospheric pressure liquid storage unit 300. The atmospheric pressure liquid storage unit 300 is connected to the self-pressurizing liquid storage unit 100 through the pump body 400, and the bottom of the self-pressurizing liquid storage unit 100 is connected to the vaporization unit 200. More specifically, under normal circumstances, liquid nitrogen is transported to the atmospheric pressure liquid storage unit 300 under pressure, then pressurized by the pump body 400 and transferred to the self-pressurizing liquid storage unit 100, and then enters the vaporization unit 200 for vaporization and is sent to the pipeline network. Since the self-pressurizing liquid storage unit 100 can supply gas even when power is off, such a liquid nitrogen backup device 1000 does not need to be equipped with an emergency pump body 400'. Although this liquid nitrogen backup device 1000 can use the self-pressurizing liquid storage unit 100 for nitrogen supply, has a fast response time, reduces energy consumption, and can still supply gas when the system is powered off, solving the technical problems of the first liquid nitrogen backup device 1000, but when the self-pressurizing liquid storage unit 100 is in long-term standby, affected by the ambient temperature and heat preservation effect, it will generate evaporation loss of liquid nitrogen by itself and directly discharge it, resulting in waste. Moreover, it is also necessary to regularly start the pump body 400 for liquid replenishment. The pre-cooling of the pump body 400 before startup and the residual liquid discharge after the pump stops will both generate a certain amount of liquid nitrogen loss, increasing the use cost. At the same time, the start / stop times of the pump body 400 are relatively many, which will increase equipment wear.

[0045] The air separation system of the present application is different from the above-mentioned prior art in that liquid nitrogen directly enters the atmospheric pressure liquid storage unit 300. It adopts a structure in which liquid nitrogen first enters the self-pressurizing liquid storage unit 100 and then enters the atmospheric pressure liquid storage unit 300. When the pipeline network pressure drops abnormally, the self-pressurizing liquid storage unit 100 has sufficient pressure and liquid level and can still supply nitrogen when the factory is powered off, without the need to install an emergency pump body 400' and the expected supporting accessories, saving costs and reducing energy consumption. And the liquid nitrogen consumption generated by a short-term abnormality in the self-pressurizing liquid storage unit 100 can be directly supplemented by the device. Specifically, the liquid nitrogen backup device 1000 can transport the liquid nitrogen in the atmospheric pressure liquid storage unit 300 to the self-pressurizing liquid storage unit 100 under pressure and automatically supply nitrogen. The response speed is fast, the power consumption and liquid nitrogen loss are low, it can quickly and stably maintain the pipeline network pressure, and the self-pressurizing liquid storage unit 100 and the rectification device 2000 are interconnected, which can maintain the internal pressure balance of the self-pressurizing liquid storage unit 100 and reduce the waste of material discharge when the self-pressurizing liquid storage unit 100 is depressurized.

[0046] It should be specifically noted here that in this application, the term "connected" should be understood in a broad sense, which includes direct connection and indirect connection through other units. There may be a material flow path between the directly or indirectly connected units, and the material can flow between the units through pipelines including but not limited to various pipelines. Or, there may not be a complete material flow path between the directly or indirectly connected units. For example, there may be a flow path for the same material between three sequentially connected units. For example, liquid nitrogen can flow through the pipelines through the first to the third units in sequence. Or, there may not be a connected flow path for the same material between three sequentially connected units. For example, a liquid material can be supplied from the unit at the most upstream in the material flow direction to the second (middle) unit, and then converted into a gaseous material and supplied to the third unit. That is, the first to the third units are sequentially connected, but liquid nitrogen cannot flow through the first to the third units in sequence. For example, in some examples, the atmospheric pressure liquid storage unit 300 is indirectly connected to the rectification device 2000 through the self-pressurizing liquid storage unit 100, that is, liquid nitrogen can be sequentially supplied from the rectification device 2000 to the self-pressurizing liquid storage unit 100 and the atmospheric pressure liquid storage unit 300, but the liquid nitrogen in the atmospheric pressure liquid storage unit 300 cannot be directly supplied in the reverse direction to the rectification device 2000.

[0047] The following further details each unit and component of the air separation system according to specific embodiments of the present invention:

[0048] According to an embodiment of the present invention, such as Figure 1As shown, in this air separation system, the liquid supply pipeline may include one or more of the first to fourth liquid supply pipelines. In one example, it may include a first liquid supply pipeline 610, a second liquid supply pipeline 620, a third liquid supply pipeline 630, and a fourth liquid supply pipeline 640. Specifically, one end of the first liquid supply pipeline 610 is connected to the rectification device 2000, specifically to the high-pressure side of the rectification device 2000. Moreover, the other end of the first liquid supply pipeline 610 is connected to the self-pressurizing liquid storage unit 100, for example, to the side wall at the top of the self-pressurizing liquid storage unit 100, to transport the liquid nitrogen from the high-pressure side of the rectification device 2000 to the self-pressurizing liquid storage unit 100. And in a specific embodiment, the height of the self-pressurizing liquid storage unit 100 may be made not higher than the height of the rectification device 2000. For example, the height of the end of the first liquid supply pipeline 610 connected to the high-pressure side of the rectification device 2000 is higher than the end connected to the self-pressurizing liquid storage unit 100, so that the liquid nitrogen can be transported from the rectification device 2000 to the self-pressurizing liquid storage unit 100 under pressure. More specifically, one end of the second liquid supply pipeline 620 is connected to the bottom of the self-pressurizing liquid storage unit 100, and the other end is connected to the vaporization unit 200, to transport the liquid nitrogen in the self-pressurizing liquid storage unit 100 to the vaporization unit 200 for vaporization to generate nitrogen. And in a specific embodiment, the vaporization unit 200 is used to vaporize the liquid nitrogen into nitrogen. Therefore, the vaporization unit 200 has a liquid inlet 210 and a gas outlet 220, and the liquid inlet 210 is connected to the second liquid supply pipeline 620, and the gas outlet 220 is connected to the gas supply pipeline 700 to send the nitrogen out to the pipe network. One end of the third liquid supply pipeline 630 is connected to the bottom of the self-pressurizing liquid storage unit 100, and the other end is connected to the normal-pressure liquid storage unit 300, for example, it may be connected to the top of the normal-pressure liquid storage unit 300, to transport the liquid nitrogen inside the self-pressurizing liquid storage unit 100 to the inside of the normal-pressure liquid storage unit 300 for storage and standby. In a specific embodiment, the ends of the second liquid supply pipeline 620 and the third liquid supply pipeline 630 connected to the bottom of the self-pressurizing liquid storage unit 100 may be interconnected, that is to say, the second liquid supply pipeline 620 and the third liquid supply pipeline 630 may be connected to the self-pressurizing liquid storage unit 100 through the same pipeline. In addition, one end of the fourth liquid supply pipeline 640 is connected to the normal-pressure liquid storage unit 300, and the other end is connected to the self-pressurizing liquid storage unit 100, such as to the side wall at the top of the self-pressurizing liquid storage unit 100, to transport the liquid nitrogen stored inside the normal-pressure liquid storage unit 300 to the self-pressurizing liquid storage unit 100 under pressure, automatically replenish nitrogen to the self-pressurizing liquid storage unit 100, and ensure that there is enough liquid nitrogen inside the self-pressurizing liquid storage unit 100 to be transported to the vaporization unit 200 to be vaporized into nitrogen and then sent out. That is to say, a circulation loop can be formed between the self-pressurizing liquid storage unit 100 and the normal-pressure liquid storage unit 300 through the third liquid supply pipeline 630 and the fourth liquid supply pipeline 640.

[0049] According to an embodiment of the present invention, referring toFigure 4 , the air separation system further includes an exhaust gas pipeline 800, and the liquid supply pipeline may further include a fifth liquid supply pipeline 650. Specifically, the exhaust gas pipeline 800 is connected to the self-pressurizing liquid storage unit 100 to discharge the nitrogen gas flashed inside the self-pressurizing liquid storage unit 100, so as to avoid excessive pressure affecting the normal operation of the device. To avoid waste of nitrogen gas and cold energy, one end of the exhaust gas pipeline 800 can be connected to the top of the self-pressurizing liquid storage unit 100, and the other end of the exhaust gas pipeline 800 can be connected to the high-pressure side of the rectification device 2000 to discharge the nitrogen gas into the rectification device 2000 for reuse. In addition, in the specific implementation manner, refer to Figure 5 , the air separation system may further include an exhaust gas pipeline 800 and a cold energy recovery device 50, wherein one end of the exhaust gas pipeline 800 is connected to the top of the self-pressurizing liquid storage unit 100, and the other end is connected to the cold energy recovery device 50. Or in a specific example, the other end of the exhaust gas pipeline 800 can be connected to both the high-pressure side of the rectification device 2000 and the cold energy recovery device 50 (not shown in the figure) to realize the recycling of nitrogen gas and avoid energy waste. More specifically, one end of the fifth liquid supply pipeline 650 is connected to the bottom of the self-pressurizing liquid storage unit 100, and the other end is connected to the low-pressure side of the rectification device 2000 to transport the liquid nitrogen inside the self-pressurizing liquid storage unit 100 to the low-pressure side of the rectification device 2000 for start-up backfilling during the start-up of the air separation system, reducing the start-up time of the system, advancing the external supply of nitrogen gas, shortening the supply time of the liquid nitrogen reserve device 1000, and reducing energy consumption and operating costs. In the specific implementation manner, the fifth liquid supply pipeline 650, the second liquid supply pipeline 620, and the third liquid supply pipeline 630 can be connected to the self-pressurizing liquid storage unit 100 through the same pipeline. That is to say, the self-pressurizing liquid storage unit 100 can supply liquid nitrogen to different positions through the fifth liquid supply pipeline 650, the second liquid supply pipeline 620, and the third liquid supply pipeline 630.

[0050] According to an embodiment of the present invention, in order to better control the normal transportation of liquid nitrogen or nitrogen gas and maintain the normal operation of the air separation system, one or more control components can be further provided inside the system. For example, the control components include but are not limited to at least one of a regulating valve, a pump body, a gas valve, a liquid level gauge, and a pressure gauge.

[0051] For example, refer to Figure 6, a first gas valve 11 and a first pressure gauge 21 may be provided on the gas supply pipeline 700 connected to the gas outlet 220 of the vaporization unit 200 to control the external delivery of nitrogen. Specifically, the first gas valve 11 may be provided at one end of the gas supply pipeline 700 close to the vaporization unit 200, and the first pressure gauge 21 may be connected to the first gas valve 11 and the gas supply pipeline 700 away from the vaporization unit 200 to monitor the pressure of the gas supply pipeline 700 by using the first pressure gauge 21. When the pressure drops, the first gas valve 11 is opened to transport nitrogen to maintain the stable pressure in the gas supply pipeline 700. In a specific embodiment, the self-pressurizing liquid storage unit 100 may be respectively connected to a second pressure gauge 22, a liquid level gauge 31, and a second gas valve 12. Specifically, the liquid level gauge 31 may be connected to the self-pressurizing liquid storage unit 100 to monitor the liquid level inside the self-pressurizing liquid storage unit 100 and avoid the liquid nitrogen level inside the self-pressurizing liquid storage unit 100 being too high or too low. The second gas valve 12 may be provided on the exhaust pipeline 800 connected to the self-pressurizing liquid storage unit 100, and the second pressure gauge 22 is connected to the second gas valve 12 and the self-pressurizing liquid storage unit 100 to monitor the pressure inside the self-pressurizing liquid storage unit 100 by using the second pressure gauge 22. When the pressure is too high, the second gas valve 12 is opened to discharge nitrogen, and when the pressure is too low, the second gas valve 12 is closed to reduce the external discharge of nitrogen. That is to say, in this application, by connecting the second pressure gauge 22, the liquid level gauge 31, and the second gas valve 12, the liquid level and pressure inside the self-pressurizing liquid storage unit 100 are kept stable to maintain the normal operation of the system.

[0052] In addition, a first regulating valve 41, a pump body 400, or a combination thereof may be further provided on the fourth liquid supply pipeline 640. Preferably, the first regulating valve 41 and the pump body 400 are provided simultaneously. When the system is shut down for a long time and the pressure difference between the normal-pressure liquid storage unit 300 and the self-pressurizing liquid storage unit 100 is not sufficient to transport the liquid nitrogen stored in the normal-pressure liquid storage unit 300 to the self-pressurizing liquid storage unit 100 for replenishment, the first regulating valve 41 and the pump body 400 may be used to transport the liquid nitrogen stored in the normal-pressure liquid storage unit 300 to the self-pressurizing liquid storage unit 100 to replenish the liquid nitrogen consumption. Specifically, the first regulating valve 41 may be opened, the pump body 400 may be started, and the liquid nitrogen is pressurized and transferred to the self-pressurizing liquid storage unit 100 to maintain the long-term operation of the liquid nitrogen backup device 1000.

[0053] According to an embodiment of the present invention, in addition to Figure 6 the control components shown in, the air separation system of this application may further include other control components. For example, refer to Figure 7, a second regulating valve 42 may be provided on the second liquid supply pipeline 620 to control the flow rate of liquid nitrogen flowing into the vaporization unit 200. In a specific embodiment, the second regulating valve 42 may be provided at one end of the second liquid supply pipeline 620 close to the vaporization unit 200. A third regulating valve 43 may be provided on the third liquid supply pipeline 630 to control the flow rate of liquid nitrogen flowing into the normal pressure liquid storage unit 300. In a specific embodiment, the third regulating valve 43 may be provided at one end of the third liquid supply pipeline 630 close to the normal pressure liquid storage unit 300. A fourth regulating valve 44 may be provided on the fifth liquid supply pipeline 650. When the device is in a hot start state, the fourth regulating valve 44 is opened to inject the liquid nitrogen in the self-pressurizing liquid storage unit 100 back into the rectification device 2000, reducing the start-up time required. In addition, a fifth regulating valve 45 and a third pressure gauge 23 may be further provided on the first liquid supply pipeline 610 to monitor the pressure of the liquid nitrogen in the rectification device 2000 by using the third pressure gauge 23 and control the flow rate of the liquid nitrogen flowing into the interior of the self-pressurizing liquid storage unit 100 through the fifth regulating valve 45. In a specific embodiment, a sixth regulating valve 46 may also be provided at one end of the first liquid supply pipeline 610 close to the self-pressurizing liquid storage unit 100, a seventh regulating valve 47 may be provided at one end of the fourth liquid supply pipeline 640 close to the self-pressurizing liquid storage unit 100, and an eighth regulating valve 48 may be provided on the gas supply pipeline 700 close to the rectification device 2000 to more precisely control the flow rate of the materials at various positions in the above pipelines or to prevent backflow. In addition, the gas supply pipeline 700 close to the rectification device 2000 may be further connected to the safety pipeline 900, and a ninth regulating valve 49 may be provided on the safety pipeline 900. When the pressure on the high-pressure side of the rectification device 2000 is too high, the ninth regulating valve 49 is opened to discharge some nitrogen gas to maintain the stable operation of the system.

[0054] In addition, it should be noted that in the air separation system of the present application, the positions and quantities of the regulating valves, pump bodies, gas valves, liquid level gauges, and pressure gauges, as well as the positions and quantities of other control components, are not limited to those shown in the drawings of the present application and can be adjusted arbitrarily without affecting the normal use of the air separation system.

[0055] According to an embodiment of the present invention, the air separation system can be used for separating, including but not limited to, nitrogen gas, and can also be used for separating or storing other low-temperature gases or low-temperature liquid products. For example, the liquid nitrogen backup device 1000 of the present application can also be used as a backup device for other low-temperature liquid products.

[0056] In another aspect of the present invention, the present invention provides a method of using the above-mentioned air separation system, the method comprising: conveying liquid nitrogen from the high-pressure side of the rectification device to the self-pressurizing liquid storage unit via a first liquid supply pipeline, and flashing off a part of nitrogen in the self-pressurizing liquid storage unit; conveying the liquid nitrogen in the self-pressurizing liquid storage unit from the bottom to the vaporization unit to generate nitrogen, and / or conveying it to the atmospheric pressure liquid storage unit for backup storage; supplying the nitrogen generated in the self-pressurizing liquid storage unit to the high-pressure side of the rectification device for recycling, and / or conveying it to the cold energy recovery device for cold energy recovery; and supplying the nitrogen on the high-pressure side of the rectification device and the nitrogen generated by the vaporization unit to the gas supply pipeline. The method has at least one of the following beneficial effects: fast response time, reduced material discharge, convenient operation, low cost, and low energy consumption.

[0057] According to an embodiment of the present invention, taking the use of Figure 7 the air separation system shown as an example, when the system is operating normally, the nitrogen on the high-pressure side of the rectification device 2000 can be sent to the pipe network via the gas supply pipeline 700, and the liquid nitrogen backup device 1000 is used as a backup to still be able to send nitrogen out when the system operates abnormally. Specifically, when the system is in a normal operating state, it is necessary to ensure the stable internal pressure of the self-pressurizing liquid storage unit 100 in the liquid nitrogen backup device 1000 so that it has sufficient pressure and liquid level to meet the conditions for sending nitrogen out. When the internal pressure of the self-pressurizing liquid storage unit 100 is too high, the liquid nitrogen from the high-pressure side of the rectification device 2000 cannot flow into the self-pressurizing liquid storage unit 100. When the internal pressure of the self-pressurizing liquid storage unit 100 is too low, the pressure conditions for sending nitrogen out cannot be met. In the specific implementation, the pressure difference between the internal pressure of the self-pressurizing liquid storage unit 100 and the pressure of the liquid nitrogen in the rectification device 2000 can be made not higher than 0.1 MPAG, that is, the pressure difference between the pressure at the top of the self-pressurizing liquid storage unit 100 and the first liquid supply pipeline 610 is made not higher than 0.1 MPAG. That is, the pressure difference between the gas phase pressure at the top of the self-pressurizing liquid storage unit 100 and the third pressure gauge 23 is made not higher than 0.1 MPAG, that is, the pressure difference between the second pressure gauge 22 and the third pressure gauge 23 is made not higher than 0.1 MPAG. Since the height of the general rectification device 2000 is more than 20 meters, the height difference between the rectification device 2000 and the self-pressurizing liquid storage unit 100 can generate a liquid column static pressure. Under the pressure range conditions defined in this application, the liquid nitrogen in the rectification device 2000 can flow into the self-pressurizing liquid storage unit 100, and the liquid nitrogen generated in the self-pressurizing liquid storage unit 100 can be discharged to the rectification device 2000 via the exhaust pipeline for secondary utilization.

[0058] According to an embodiment of the present invention, the second regulating valve 42 can be kept in an always-open state so that liquid nitrogen can flow into the vaporization unit 200 to be vaporized into nitrogen. When the pressure of the gas supply pipeline 700 decreases, that is, when the pressure value of the first pressure gauge 21 decreases, the first gas valve 11 can be opened to allow the liquid nitrogen in the self-pressurizing liquid storage unit 100 to enter the vaporization unit 200 under the push of pressure for vaporization, and after being reheated, it is transported to the gas supply pipeline 700 to maintain the pressure stability of the gas supply pipeline 700, that is, to maintain the stability of the pressure value of the first pressure gauge 21. In a specific embodiment, the first gas valve 11 can be in an automatic opening and closing state, so that when the pressure value of the first pressure gauge 21 changes, the first gas valve 11 can automatically open and close to adjust the pressure of the gas supply pipeline 700, with a faster response time, lower power consumption and liquid nitrogen loss, and a faster pressure stabilizing effect on the gas supply pipeline 700.

[0059] According to an embodiment of the present invention, when there is too much liquid nitrogen inside the self-pressurizing liquid storage unit 100, that is, when the liquid level is too high, the third regulating valve 43 can be opened to transport the liquid nitrogen to the atmospheric pressure liquid storage unit 300 with a larger volume for storage and standby. Alternatively, in a specific embodiment, the third regulating valve 43 can be kept at a slightly open state all the time, so that the liquid nitrogen inside the self-pressurizing liquid storage unit 100 always slowly flows into the atmospheric pressure liquid storage unit 300 for storage and standby, so as to avoid too much liquid nitrogen inside the self-pressurizing liquid storage unit 100 and maintain the liquid level inside the self-pressurizing liquid storage unit 100 in a balanced state all the time.

[0060] According to an embodiment of the present invention, the nitrogen gas generated in the self-pressurizing liquid storage unit 100 can be transported to the high-pressure side of the rectification device 2000 for recycling, reducing the waste of material discharge when the self-pressurizing liquid storage unit 100 is depressurized, and at the same time being more convenient to operate. In a specific embodiment, the nitrogen gas generated in the self-pressurizing liquid storage unit 100 can also be transported to the cold energy recovery device for cold energy recovery.

[0061] According to an embodiment of the present invention, when the air separation system experiences a shutdown, the liquid nitrogen in the atmospheric pressure liquid storage unit 300 can be transported into the self-pressurizing liquid storage unit 100, so that the self-pressurizing liquid storage unit 100 vaporizes the liquid nitrogen into nitrogen for supplementary supply, replacing the nitrogen sent out by the air separation nitrogen production system. Specifically, when a short-term shutdown occurs, the first regulating valve 41 can be opened to make the liquid nitrogen in the atmospheric pressure liquid storage unit 300 be transported into the self-pressurizing liquid storage unit 100 under pressure to maintain the nitrogen supply. However, when an extreme situation occurs and the air separation system shuts down for too long, it is necessary to continuously use the liquid nitrogen backup device 1000 to supply nitrogen. As the pressure in the atmospheric pressure liquid storage unit 300 gradually decreases and is not sufficient to transport the liquid nitrogen to the self-pressurizing liquid storage unit 100, the pump body 400 can be started to pressurize and transfer the liquid nitrogen into the self-pressurizing liquid storage unit 100, so that the liquid nitrogen backup device 1000 can operate for a long time. That is to say, the air separation system of the present application can reduce the startup times and time of the pump body 400. Only when there is a long-term shutdown is it necessary to start the pump body 400. The liquid nitrogen consumption caused by a short-term abnormality to the self-pressurizing liquid storage unit 100 can be directly supplemented without starting the pump body 400, reducing energy consumption and the usage loss of the pump body 400.

[0062] According to an embodiment of the present invention, when the air separation system is in a hot startup state, the fourth regulating valve 44 can be opened to reverse-inject a certain amount of liquid nitrogen into the low-pressure side of the rectification device 2000, reducing the startup time required, sending out nitrogen in advance, shortening the backup liquid nitrogen supply time at the same time, reducing the overall energy consumption, and reducing the operating cost.

[0063] Generally speaking, the air separation system proposed by the present invention adopts a liquid nitrogen backup device 1000 in which the liquid nitrogen in the rectification device 2000 first enters the self-pressurizing liquid storage unit 100 and then enters the atmospheric pressure liquid storage unit 300. The self-pressurizing liquid storage unit 100 has sufficient pressure and liquid level, and can still send out nitrogen for nitrogen supplementary supply when the factory power fails. The response speed is fast, the power consumption and liquid nitrogen loss are low, the pipe network pressure can be quickly stabilized, and the self-pressurizing liquid storage unit 100 is interconnected with the rectification device 2000, which can maintain the internal pressure balance of the self-pressurizing liquid storage unit 100, reduce the waste of material discharge when the self-pressurizing liquid storage unit 100 relieves pressure, save costs, and reduce energy consumption.

[0064] The foregoing has shown and described the basic principles, main features and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting.

[0065] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present disclosure, "a plurality of" means two or more unless otherwise specifically defined.

[0066] In the present disclosure, unless otherwise clearly specified and defined, terms such as "installed", "connected", "joined", "fixed", etc. shall be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal connection of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0067] The above disclosure provides many different embodiments or examples for implementing different structures of the present disclosure. To simplify the present disclosure, components and settings of specific examples are described above. Of course, they are only examples and are not intended to limit the present disclosure. In addition, the present disclosure may repeat reference numerals and / or reference letters in different examples. Such repetition is for the purpose of simplification and clarity and does not itself indicate the relationship between the various embodiments and / or settings discussed.

[0068] In addition, it should be understood that although this specification is described according to embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An air separation system, characterized in that, It includes a rectification device and a liquid nitrogen backup device, and the liquid nitrogen backup device includes a self-pressurizing liquid storage unit, a vaporization unit, and an atmospheric pressure liquid storage unit; The self-pressurizing liquid storage unit is connected to the rectification device, and the atmospheric pressure liquid storage unit is connected to the rectification device through the self-pressurizing liquid storage unit; The vaporization unit and the atmospheric pressure liquid storage unit are respectively connected to the self-pressurizing liquid storage unit through liquid supply pipelines; The vaporization unit and the rectification device are both connected to a gas supply pipeline.

2. The air separation system according to claim 1, wherein It further includes an exhaust pipeline, one end of the exhaust pipeline is connected to the top of the self-pressurizing liquid storage unit, and the other end is connected to the high-pressure side of the rectification device.

3. The air separation system according to claim 1, wherein, It further includes an exhaust pipeline and a cold energy recovery device, one end of the exhaust pipeline is connected to the top of the self-pressurizing liquid storage unit, and the other end is connected to the cold energy recovery device.

4. The air separation system according to claim 1, wherein The liquid supply pipeline includes a first liquid supply pipeline, a second liquid supply pipeline, and a third liquid supply pipeline; The first liquid supply pipeline connects the high-pressure side of the rectification device and the top of the self-pressurizing liquid storage unit; The second liquid supply pipeline connects the bottom of the self-pressurizing liquid storage unit and the vaporization unit; The third liquid supply pipeline connects the bottom of the self-pressurizing liquid storage unit and the atmospheric pressure liquid storage unit.

5. The air separation system according to claim 4, characterized in that, It further includes a fourth liquid supply pipeline, and the fourth liquid supply pipeline connects the atmospheric pressure liquid storage unit and the self-pressurizing liquid storage unit; And a first regulating valve and a pump body are provided on the fourth liquid supply pipeline.

6. The air separation system according to claim 4, characterized in that, It further includes a fifth liquid supply pipeline, and the fifth liquid supply pipeline connects the bottom of the self-pressurizing liquid storage unit and the low-pressure side of the rectification device.

7. The air separation system according to claim 1, characterized in that The vaporization unit includes a gas outlet and a liquid inlet, and a first gas valve and a first pressure gauge are provided on the gas supply pipeline connected to one side of the gas outlet.

8. The air separation system according to claim 1, wherein The height of the self-pressurizing liquid storage unit is not higher than the height of the rectification device.

9. The air separation system according to claim 1, characterized in that The self-pressurizing liquid storage unit is connected with a second pressure gauge, a liquid level gauge, and a second gas valve; Among them, the second gas valve is located on the exhaust pipeline.

10. The air separation system according to claim 1, characterized in that, Meet at least one of the following conditions: A second regulating valve is provided on the second liquid supply pipeline; A third regulating valve is provided on the third liquid supply pipeline; A fourth regulating valve is provided on the fifth liquid supply pipeline.

11. A method of using the air separation system according to any one of claims 1-10, characterized in that, The method includes: Transport the liquid nitrogen from the high-pressure side of the rectification device to the self-pressurizing liquid storage unit through the first liquid supply pipeline; Transport the liquid nitrogen in the self-pressurizing liquid storage unit from the bottom to the vaporization unit to generate nitrogen gas, and / or transport it to the atmospheric pressure liquid storage unit for backup storage; Supply the nitrogen gas generated in the self-pressurizing liquid storage unit to the high-pressure side of the rectification device for recycling, and / or transport it to the cold energy recovery device for cold energy recovery; Supply the nitrogen gas on the high-pressure side of the rectification device and the nitrogen gas generated by the vaporization unit to the gas supply pipeline.

12. The method according to claim 11, wherein Make the pressure difference between the pressure at the top of the self-pressurizing liquid storage unit and the pressure in the first liquid supply pipeline not higher than 0.1 MPAG; When the pressure value of the first pressure gauge decreases, open the first gas valve, so that the liquid nitrogen in the self-pressurizing liquid storage unit enters the vaporization unit for vaporization under the action of pressure, and is transported to the gas supply pipeline to maintain the stability of the pressure value of the first pressure gauge.

13. The method according to claim 11, wherein It further includes at least one of the following steps: Open the third regulating valve to deliver liquid nitrogen to the atmospheric pressure liquid storage unit; Keep the third regulating valve slightly open to maintain the liquid level balance in the atmospheric pressure liquid storage unit.

14. The method according to claim 11, wherein When a shutdown condition occurs, it further includes: Deliver the liquid nitrogen in the atmospheric pressure liquid storage unit to the inside of the self-pressurizing liquid storage unit to vaporize the liquid nitrogen into nitrogen through the self-pressurizing liquid storage unit.

15. The method according to claim 11, wherein When the air separation system is in the hot start state, it further includes: Open the fourth regulating valve to reverse-inject liquid nitrogen to the low-pressure side of the rectification device.

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