A low-pressure oxygen emergency supply system for air separation unit backup

Abstract

The application discloses a kind of air separation device backup low-pressure oxygen emergency supply system, including backup oxygen converter, water bath gasifier, emergency supply pipeline and control unit, high-pressure liquid oxygen inlet pipeline of backup oxygen converter is connected with high-pressure liquid oxygen source, and the outlet end of backup oxygen converter is connected with water bath gasifier, the outlet end of water bath gasifier is connected with low-pressure oxygen pipe network, import manual valve is installed on the outside of import pipeline of water bath gasifier, outlet manual valve is installed on the outside of outlet pipeline of water bath gasifier, emergency supply pipeline includes first branch pipeline and second branch pipeline;The beneficial effects of the application: the special low-pressure oxygen emergency supply pipeline is built in the application, and continuous and stable supply of low-pressure oxygen can be realized when air separation main device stops;By matching setting safety facilities such as pressure reducing valve and safety valve, accurate control of pressure and overpressure protection can be realized, and the safety risk of high-pressure string low-pressure is avoided.

Description

Technical Field

[0001] This invention relates to the field of oxygen supply technology for air separation units, specifically to a backup low-pressure oxygen emergency supply system for air separation units. Background Technology

[0002] Low-pressure oxygen in air separation units is the core raw material for subsequent process units such as sulfur recovery. In the existing technology, the conventional supply path for low-pressure oxygen in air separation is as follows: after the high-pressure liquid oxygen in set C air separation is depressurized, it enters the high-pressure plate heat exchanger for heat exchange, forming low-pressure oxygen, which is then supplied to the subsequent pipeline network.

[0003] When the C-set air separation cold box malfunctions and shuts down, high-pressure oxygen can be supplied as an emergency through the backup oxygen system. However, the existing system lacks a dedicated emergency supply pipeline for low-pressure oxygen; it can only supply oxygen to the second-phase low-pressure oxygen network via a connecting pipeline from the first-phase low-pressure oxygen process pump. The design pressure and rated flow rate of the first-phase low-pressure oxygen process pump cannot meet the operating requirements of the second-phase sulfur recovery unit, directly causing the sulfur recovery unit to shut down. This would lead to environmental problems such as excessive exhaust emissions, and also cause unplanned shutdowns of the production system, resulting in significant economic losses.

[0004] Therefore, there is an urgent need to develop an emergency supply system that can stably supply low-pressure oxygen when the main air separation unit is shut down, in order to solve the technical deficiency of existing technologies that lack a reliable emergency supply path for low-pressure oxygen. Summary of the Invention

[0005] The purpose of this invention is to provide a backup low-pressure oxygen emergency supply system for air separation units, so as to solve the technical defects in the prior art where there is no reliable emergency supply path for low-pressure oxygen when the main air separation unit is shut down, which leads to the shutdown of subsequent process units and causes environmental problems.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a backup low-pressure oxygen emergency supply system for an air separation unit, comprising a backup oxygenator, a water bath vaporizer, an emergency supply pipeline, and a control unit. The high-pressure liquid oxygen inlet pipeline of the backup oxygenator is connected to a high-pressure liquid oxygen source, and the outlet end of the backup oxygenator is connected to the water bath vaporizer. The outlet end of the water bath vaporizer is connected to a low-pressure oxygen pipeline network. An inlet manual valve is installed on the outside of the inlet pipeline of the water bath vaporizer, and an outlet manual valve is installed on the outside of the outlet pipeline of the water bath vaporizer.

[0007] The emergency supply pipeline includes a first branch pipeline and a second branch pipeline. One end of the first branch pipeline is connected to the high-pressure liquid oxygen inlet pipeline of the backup oxidizer, and the other end of the first branch pipeline is connected to the pipeline after the inlet manual valve of the water bath vaporizer. A first manual valve and a pressure reducing valve are installed sequentially on the outside of the first branch pipeline. One end of the second branch pipeline is connected to the pipeline before the outlet manual valve of the water bath vaporizer, and the other end of the second branch pipeline is connected to the reserved port of the third phase of the low-pressure oxygen pipeline network.

[0008] The control unit is connected to the pressure reducing valve, and the control unit is used to control the opening degree of the pressure reducing valve, reducing the pressure of high-pressure liquid oxygen from the first preset pressure to the second preset pressure, and controlling the flow rate of low-pressure oxygen supplied in emergencies to a preset flow rate range.

[0009] Preferably, the preset pressure is 8.5 MPa, the second preset pressure is 0.6 MPa, and the preset flow rate range is 1000-1680 Nm³ / h.

[0010] Preferably, the safety protection unit includes a first safety valve, a second safety valve, and a third safety valve. The first safety valve is installed on the outside of the high-pressure liquid oxygen inlet pipe of the backup oxidizer, and the first safety valve is used to control the pressure of the high-pressure side pipe. The second safety valve is installed on the outside of the first branch pipe between the pressure reducing valve and the inlet pipe of the water bath vaporizer, and the second safety valve is used to control the pressure of the pipe after pressure reduction. The third safety valve is installed on the outside of the outlet pipe of the water bath vaporizer, and the third safety valve is used to control the pressure of the low-pressure oxygen network.

[0011] Preferably, the pressure reducing valve is a DN25 stainless steel regulating valve, model PV-001, with a design pressure of 9.8MPa, a design temperature of -196-60℃, a medium of liquid oxygen, a valve inlet pressure of 8.5MPa, and a valve outlet pressure of 0.6MPa.

[0012] Preferably, the pipes, valves, and flanges of the emergency supply pipeline are all degreased, and the pipe material is 06Cr18Ni11Ti stainless steel.

[0013] Preferably, the original medium of the water bath vaporizer is liquid nitrogen, with a design pressure of 13.2 MPa and a design temperature of -196℃.

[0014] Preferably, the emergency supply pipeline includes 20 meters of DN25 stainless steel pipe and 80 meters of DN80 stainless steel pipe.

[0015] Preferably, the first manual valve has a specification of 600LB DN25; the set pressure of the second safety valve and the third safety valve is 0.8MPa.

[0016] Preferably, the pipeline originally connected to the backup oxygenator at the inlet end of the water bath vaporizer is physically isolated by a blind flange.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. This invention establishes a dedicated low-pressure oxygen emergency supply pipeline, which enables a continuous and stable supply of low-pressure oxygen when the main air separation unit is shut down, thus completely solving the technical defect of no reliable emergency supply path for low-pressure oxygen in the prior art.

[0019] 2. By incorporating safety features such as pressure reducing valves and safety valves, this invention enables precise pressure control and overpressure protection, avoiding the safety risks of high pressure passing through low pressure and ensuring the safe operation of the system.

[0020] 3. This invention can fully meet the low-pressure oxygen requirements of the second-phase sulfur recovery unit, avoid sulfur recovery shutdowns caused by low-pressure oxygen interruptions, thereby eliminating environmental problems and ensuring the stable operation of the production system. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the pipeline connection structure of the backup low-pressure oxygen emergency supply system for the air separation unit of the present invention;

[0022] Figure 2 This is a schematic diagram of the present invention;

[0023] Figure 3 This is a block diagram of the connection control logic between the control unit and the pressure reducing valve of the present invention;

[0024] Figure 4 This is a schematic diagram of the safety protection unit of the present invention.

[0025] In the diagram: 1. Backup oxygen aerator E43; 2. Water bath vaporizer; 3. Emergency supply pipeline; 4. First branch pipeline; 5. Second branch pipeline; 6. Low-pressure oxygen network; 7. High-pressure liquid oxygen source; 8. First safety valve; 9. Inlet manual valve; 10. Outlet manual valve; 11. Control unit; 12. Safety protection unit; 13. Pressure reducing valve; 14. Second safety valve; 15. Third safety valve; 16. First manual valve. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 1-4 The present invention provides a technical solution: a backup low-pressure oxygen emergency supply system for an air separation unit, comprising a backup oxygen aerator 1, a water bath vaporizer 2, an emergency supply pipeline 3, and a control unit 11. The high-pressure liquid oxygen inlet pipeline of the backup oxygen aerator 1 is connected to a high-pressure liquid oxygen source 7, and the outlet end of the backup oxygen aerator 1 is connected to the water bath vaporizer 2. The outlet end of the water bath vaporizer 2 is connected to a low-pressure oxygen pipeline network 6. An inlet manual valve 9 is installed on the outside of the inlet pipeline of the water bath vaporizer 2, and an outlet manual valve 10 is installed on the outside of the outlet pipeline of the water bath vaporizer 2.

[0028] It should be noted that in this embodiment, the backup oxidizer 1 is the backup oxidizer E43, and the water bath vaporizer 2 is the water bath vaporizer E53. The rated operating pressure of the backup oxidizer E43 is 8.5 MPa, the operating temperature is -186℃, and the medium is high-pressure liquid oxygen. The rear outlet of the backup oxidizer E43 is connected to the inlet of the water bath vaporizer E53 through the original pipeline. However, under normal operating conditions, a blind flange is installed on the original pipeline for physical isolation to prevent cross-flow of the medium.

[0029] The emergency supply pipeline 3 includes a first branch pipeline 4 and a second branch pipeline 5. One end of the first branch pipeline 4 is connected to the high-pressure liquid oxygen inlet pipeline of the backup oxidizer 1, and the other end of the first branch pipeline 4 is connected to the pipeline after the inlet manual valve 9 of the water bath vaporizer 2. A first manual valve 16 and a pressure reducing valve 13 are installed sequentially on the outside of the first branch pipeline 4. One end of the second branch pipeline 5 is connected to the pipeline before the outlet manual valve 10 of the water bath vaporizer 2, and the other end of the second branch pipeline 5 is connected to the third-phase reserved port of the low-pressure oxygen pipeline network 6.

[0030] It should be noted that in this embodiment, the pressure reducing valve 13 is a pressure reducing valve PV-001, and there are two first manual valves 16, both of which are 600LB DN25 stainless steel manual valves. The two first manual valves 16 are connected in series on the upstream side of the pressure reducing valve 13 to form a double shut-off isolation to improve the safety and reliability of the system. A second manual valve is installed on the second branch pipeline 5 to control the on / off of emergency oxygen.

[0031] The control unit 11 is connected to the pressure reducing valve 13, and the control unit 11 is used to control the opening degree of the pressure reducing valve 13, reducing the pressure of high-pressure liquid oxygen from the first preset pressure to the second preset pressure, and controlling the flow rate of low-pressure oxygen supplied in emergency to the preset flow rate range.

[0032] It should be noted that in this embodiment, the control unit 11 is electrically connected to the pressure reducing valve 13 and is used to control the opening degree of the pressure reducing valve 13 in order to precisely adjust the outlet pressure.

[0033] The first preset pressure is 8.5 MPa, the second preset pressure is 0.6 MPa, and the preset flow rate range is 1000-1680 Nm³ / h.

[0034] It should be noted that in this embodiment, the control unit 11 is implemented using a DCS (Distributed Control System) or a PLC (Programmable Logic Controller), which has a built-in PID (Proportional-Integral-Derivative) control algorithm. Based on the feedback signal from the pressure transmitter installed on the outlet pipeline of the pressure reducing valve 13, the control unit 11 automatically adjusts the valve opening of the pressure reducing valve 13, reducing the high-pressure liquid oxygen pressure from 8.5 MPa to 0.6 MPa, and controlling the emergency supply of low-pressure oxygen flow rate to 1000-1680 Nm³ / h.

[0035] The control unit 11 can also be adjusted manually on-site, meaning the operator can manually adjust the valve stem opening of the pressure reducing valve 13 based on the readings of the pressure gauge and flow meter. However, in this embodiment, an automatic control method is preferred to improve response speed and adjustment accuracy.

[0036] Safety protection unit 12 includes a first safety valve 8, a second safety valve 14, and a third safety valve 15. The first safety valve 8 is installed on the outside of the high-pressure liquid oxygen inlet pipe of the backup oxidizer 1. The first safety valve 8 is used to control the pressure of the high-pressure side pipe. The second safety valve 14 is installed on the outside of the first branch pipe 4 between the pressure reducing valve 13 and the inlet pipe of the water bath vaporizer 2. The second safety valve 14 is used to control the pressure of the pipe after pressure reduction. The third safety valve 15 is installed on the outside of the outlet pipe of the water bath vaporizer 2. The third safety valve 15 is used to control the pressure of the low-pressure oxygen network.

[0037] It should be noted that in this embodiment, the first safety valve 8 is the first safety valve PSV-001; the second safety valve 14 is the second safety valve PSV-002; and the third safety valve 15 is the third safety valve PSV-003.

[0038] The first safety valve, PSV-001, is installed on the high-pressure liquid oxygen inlet pipeline of the backup oxidizer E43. Its operating pressure is 8.5 MPa, and its set pressure (i.e., opening pressure) is 9.8 MPa. The medium is liquid oxygen. When the pressure in the high-pressure side pipeline exceeds 9.8 MPa, this safety valve automatically opens to release pressure, preventing the high-pressure liquid oxygen pipeline from rupturing due to overpressure. It is used to control the pressure in the high-pressure side pipeline.

[0039] The second safety valve, PSV-002, is installed in the outlet pipeline of the pressure reducing valve PV-001. Its operating pressure is 0.6 MPa, and its set pressure is 0.8 MPa, with liquid oxygen as the medium. When the pressure reducing valve PV-001 fails or malfunctions, causing the outlet pressure to exceed 0.8 MPa, this safety valve automatically opens to release pressure, preventing high-pressure oxygen from entering the low-pressure pipeline. It is used to control the pressure in the pipeline after pressure reduction. This safety valve effectively avoids the safety risk of high-pressure oxygen entering the low-pressure pipeline.

[0040] The third safety valve, PSV-003, is installed on the outlet pipeline of the water bath vaporizer E53. Its operating pressure is 0.6 MPa, its set pressure is 0.8 MPa, and its medium is oxygen. When the low-pressure oxygen pipeline pressure abnormally rises above 0.8 MPa, this safety valve automatically opens to release pressure, protecting downstream equipment (such as the sulfur recovery unit) from overpressure damage. It is used to control the pressure of the low-pressure oxygen pipeline.

[0041] The discharge ports of the first safety valve PSV-001, the second safety valve PSV-002, and the third safety valve PSV-003 are all connected to the plant's safety venting system to ensure that the discharged medium is safely disposed of.

[0042] Pressure reducing valve 13 is a DN25 stainless steel regulating valve, model PV-001, with a design pressure of 9.8MPa, a design temperature of -196-60℃, a medium of liquid oxygen, a valve inlet pressure of 8.5MPa, and a valve outlet pressure of 0.6MPa.

[0043] It should be noted that, in this embodiment, calculations show that under normal flow rate (1000 Nm³ / h), the valve's calculated Cv value is 0.1739, corresponding to a valve opening of 67.8%; under maximum flow rate (1680 Nm³ / h), the calculated Cv value is 0.2087, corresponding to a valve opening of 73.2%. This valve selection ensures good regulation accuracy and linearity across the entire flow range.

[0044] The pipes, valves and flanges of emergency supply pipeline 3 have all undergone degreasing treatment, and the pipe material is 06Cr18Ni11Ti stainless steel.

[0045] It should be noted that the pipe material of emergency supply pipeline 3 in this embodiment is 06Cr18Ni11Ti stainless steel. This material has good low-temperature toughness and corrosion resistance, and can be used in low-temperature and high-pressure environments of liquid oxygen and gaseous oxygen media. All pipes, valves and flanges have undergone strict degreasing treatment to prevent the risk of combustion or explosion caused by contact between grease and oxygen, and to ensure the safe operation of the system in an oxygen-rich environment.

[0046] The pipe length, diameter, and number of fittings described above are preferred options based on the specific engineering scenario of this embodiment. In practical applications, those skilled in the art can adaptively adjust the pipe specifications and quantity according to the plant equipment layout, pipeline distance, and flow requirements.

[0047] The original medium of the water bath vaporizer 2 is liquid nitrogen, with a design pressure of 13.2 MPa and a design temperature of -196℃.

[0048] It should be noted that the water bath vaporizer E53 in this embodiment is fully adaptable to the reheating process requirements of liquid oxygen, and can reheat liquid oxygen at -186℃ to gaseous oxygen at 25℃. Its working principle is as follows: through water bath heating, the liquid oxygen absorbs heat in the vaporizer coil and is completely vaporized, and then heated to room temperature to meet the temperature requirements of downstream process units for gaseous low-pressure oxygen.

[0049] As an alternative implementation, the water bath vaporizer 2 can also be an air bath vaporizer or other types of vaporizers, as long as they can achieve the function of reheating and vaporizing liquid oxygen. However, in this embodiment, it is preferable to reuse and modify the existing water bath vaporizer E53 in the original factory area to reduce equipment investment costs.

[0050] Emergency supply pipeline 3 includes 20 meters of DN25 stainless steel pipe and 80 meters of DN80 stainless steel pipe.

[0051] It should be noted that, in this embodiment, the supporting fittings for the emergency supply pipeline 3 include: one DN25 stainless steel tee, one DN40 to DN25 stainless steel tee, one DN100 to DN80 stainless steel tee, eight DN25 stainless steel elbows, and ten DN80 stainless steel elbows.

[0052] The first manual valve 16 has a specification of 600LB DN25; the second safety valve 14 and the third safety valve 15 both have a set pressure of 0.8MPa.

[0053] The pipeline originally connected to the backup oxygen aerator 1 at the inlet end of the water bath vaporizer 2 is physically isolated by a blind flange.

[0054] It should be noted that in this embodiment, physical isolation is achieved by setting a blind plate, which can prevent media crossflow.

[0055] The specific operation process of this invention is as follows:

[0056] Under normal operating conditions, the C-set air separation cold box is operating normally, and low-pressure oxygen is supplied by the conventional supply path. At this time, the emergency supply pipeline 3 of the present invention is in standby mode: the first manual valve 16 on the first branch pipeline 4 is closed, the pressure reducing valve 13 is in the fully closed position, and the water bath vaporizer 2 maintains a low-power standby or intermittent operation state.

[0057] When the C-set air separation cold box malfunctions and shuts down, interrupting the regular low-pressure oxygen supply path, confirm that the water bath vaporizer 2 is ready for operation. Open the heating medium inlet and outlet valves of the water bath vaporizer 2, and slowly open the two first manual valves 16 on the first branch pipeline 4 in sequence, so that high-pressure liquid oxygen is drawn out from the high-pressure liquid oxygen inlet pipeline of the backup oxygen vaporizer 1 and enters the pipeline before the pressure reducing valve 13. Set the outlet pressure of the pressure reducing valve 13 to 0.6MPa through the control unit 11, and gradually open the pressure reducing valve 13. The control unit 11 automatically adjusts the valve opening according to the feedback signal of the outlet pressure transmitter to stabilize the outlet pressure at 0.6MPa. The liquid oxygen after pressure reduction (0.6MPa, -186℃) enters the coil of the water bath vaporizer 2, and rapidly vaporizes and heats up under the action of water bath heating to form low-pressure oxygen at 25℃.

[0058] Once the outlet temperature of the water bath vaporizer 2 reaches 25℃ and the pressure stabilizes at 0.6MPa, the second manual valve on the second branch pipeline 5 is slowly opened to deliver low-pressure oxygen through the second branch pipeline 5 to the reserved port of the third-phase low-pressure oxygen pipeline network. The oxygen then enters the third-phase low-pressure oxygen pipeline network and is transported in reverse through the network to the second-phase sulfur recovery unit. The flow rate of the heating medium in the water bath vaporizer 2 is adjusted to ensure that the outlet oxygen temperature is maintained within the range of 25℃±5℃. The control unit 11 automatically adjusts the opening of the pressure reducing valve 13 according to the downstream flow demand (1000-1680 Nm³ / h) to maintain the supply flow rate matching the downstream demand.

[0059] After the C-set air separation cold box malfunction is resolved and normal supply is restored, operate in the reverse order: first close the second manual valve, then close the pressure reducing valve 13, and finally close the first manual valve 16, and restore the water bath vaporizer 2 to standby status.

[0060] In this embodiment, the system also includes a safety interlock protection logic, specifically including:

[0061] When the outlet pressure of pressure reducing valve 13 exceeds 0.7MPa (higher than the operating pressure but lower than the safety valve set pressure), the control unit will issue an audible and visual alarm.

[0062] When the outlet pressure of the pressure reducing valve 13 reaches 0.8MPa, the second safety valve 14 mechanically opens to release pressure, and at the same time the control unit 11 forcibly closes the pressure reducing valve 13 to cut off the source of high-pressure liquid oxygen.

[0063] When the outlet temperature of the water bath vaporizer 2 is below 10℃, the control unit 11 issues a low temperature alarm, and the operator should increase the flow rate of the water bath heating medium; when the outlet temperature is below 0℃, the feed valve is automatically shut off to prevent low temperature oxygen from entering the downstream carbon steel pipeline and causing the risk of brittle fracture.

[0064] The backup low-pressure oxygen emergency supply system for the air separation unit implemented in this study has been applied to the actual production scenario of the air separation unit at Yanzhou Coal Yulin Energy and Chemical Company. In actual verification, when the C-set air separation cold box underwent a simulated fault shutdown, the system successfully established an emergency low-pressure oxygen supply within 3 minutes. The outlet pressure stabilized at 0.60±0.02MPa, the outlet temperature stabilized at 25±3℃, and the supply flow rate was maintained at 1200Nm³ / h (within the range of 1000-1680Nm³ / h). This fully met the low-pressure oxygen requirements of the Phase II sulfur recovery unit, enabling continuous operation of the sulfur recovery unit without shutdown, and preventing any environmental issues such as excessive exhaust gas emissions.

[0065] In summary, this invention, by adding a dedicated emergency supply pipeline to the existing air separation unit, precisely reduces the high-pressure liquid oxygen from the backup oxidizer E43 to 0.6 MPa via the pressure reducing valve PV-001, then introduces it into the water bath vaporizer E53 for reheating into ambient temperature low-pressure oxygen. This oxygen is then transported via a second branch pipeline to the reserved port in the third phase of the low-pressure oxygen pipeline network. This provides an independent and reliable emergency supply path for the subsequent sulfur recovery unit in the event of a main air separation unit shutdown. Simultaneously, the system is equipped with a first safety valve PSV-001, a second safety valve PSV-002, and a third safety valve PSV-003 on the high-pressure side, after pressure reduction, and at the outlet pipeline, forming a three-stage overpressure protection system that effectively avoids the safety risk of high-pressure leakage to low-pressure systems.

[0066] This invention has the advantages of reasonable structure, low modification cost, convenient operation, and safety and reliability. It completely solves the technical defects of the existing technology in that there is no reliable emergency supply path for low-pressure oxygen, and avoids the environmental problems caused by unplanned shutdown of the sulfur recovery unit.

[0067] Furthermore, the terms “first,” “second,” “third,” and “fourth” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as “first,” “second,” “third,” or “fourth” may explicitly or implicitly include at least one of those features.

[0068] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "setting," "connection," "fixing," "screw connection," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components or the interaction between two components. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0069] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A backup low-pressure oxygen emergency supply system for an air separation unit, characterized in that, It includes a backup oxidizer (1), a water bath vaporizer (2), an emergency supply pipeline (3), and a control unit (11). The high-pressure liquid oxygen inlet pipeline of the backup oxidizer (1) is connected to a high-pressure liquid oxygen source (7), and the outlet end of the backup oxidizer (1) is connected to the water bath vaporizer (2). The outlet end of the water bath vaporizer (2) is connected to a low-pressure oxygen pipeline network (6). An inlet manual valve (9) is installed on the outside of the inlet pipeline of the water bath vaporizer (2), and an outlet manual valve (10) is installed on the outside of the outlet pipeline of the water bath vaporizer (2). The emergency supply pipeline (3) includes a first branch pipeline (4) and a second branch pipeline (5). One end of the first branch pipeline (4) is connected to the high-pressure liquid oxygen inlet pipeline of the backup oxidizer (1), and the other end of the first branch pipeline (4) is connected to the pipeline after the inlet manual valve (9) of the water bath vaporizer (2). A first manual valve (16) and a pressure reducing valve (13) are installed on the outside of the first branch pipeline (4) in sequence. One end of the second branch pipeline (5) is connected to the pipeline before the outlet manual valve (10) of the water bath vaporizer (2), and the other end of the second branch pipeline (5) is connected to the third-phase reserved port of the low-pressure oxygen pipeline network (6). The control unit (11) is connected to the pressure reducing valve (13), and the control unit (11) is used to control the opening degree of the pressure reducing valve (13), reduce the pressure of high-pressure liquid oxygen from the first preset pressure to the second preset pressure, and control the flow rate of low-pressure oxygen supplied in emergency to the preset flow rate range.

2. The backup low-pressure oxygen emergency supply system for an air separation unit according to claim 1, characterized in that: The preset pressure is 8.5 MPa, the second preset pressure is 0.6 MPa, and the preset flow rate range is 1000-1680 Nm³ / h.

3. The backup low-pressure oxygen emergency supply system for an air separation unit according to claim 1, characterized in that: The safety protection unit (12) includes a first safety valve (8), a second safety valve (14) and a third safety valve (15). The first safety valve (8) is installed on the outside of the high-pressure liquid oxygen inlet pipe of the backup oxygenator (1). The first safety valve (8) is used to control the pressure of the high-pressure side pipe. The second safety valve (14) is installed on the outside of the first branch pipe (4) between the pressure reducing valve (13) and the inlet pipe of the water bath vaporizer (2). The second safety valve (14) is used to control the pressure of the pipe after pressure reduction. The third safety valve (15) is installed on the outside of the outlet pipe of the water bath vaporizer (2). The third safety valve (15) is used to control the pressure of the low-pressure oxygen network.

4. The backup low-pressure oxygen emergency supply system for an air separation unit according to claim 1, characterized in that: The pressure reducing valve (13) is a DN25 stainless steel regulating valve, model PV-001, with a design pressure of 9.8MPa, a design temperature of -196-60℃, a medium of liquid oxygen, a valve inlet pressure of 8.5MPa, and a valve outlet pressure of 0.6MPa.

5. The backup low-pressure oxygen emergency supply system for an air separation unit according to claim 1, characterized in that: The pipes, valves and flanges of the emergency supply pipeline (3) have all been degreased and the pipe material is 06Cr18Ni11Ti stainless steel.

6. The backup low-pressure oxygen emergency supply system for an air separation unit according to claim 1, characterized in that: The original medium of the water bath vaporizer (2) is liquid nitrogen, with a design pressure of 13.2 MPa and a design temperature of -196℃.

7. The backup low-pressure oxygen emergency supply system for an air separation unit according to claim 1, characterized in that: The emergency supply pipeline (3) includes 20 meters of DN25 stainless steel pipe and 80 meters of DN80 stainless steel pipe.

8. The backup low-pressure oxygen emergency supply system for an air separation unit according to claim 1, characterized in that: The first manual valve (16) has a specification of 600LB DN25; the second safety valve (14) and the third safety valve (15) both have a set pressure of 0.8MPa.

9. A backup low-pressure oxygen emergency supply system for an air separation unit according to claim 1, characterized in that: The pipeline originally connected to the backup oxygenator (1) at the inlet end of the water bath vaporizer (2) is physically isolated by a blind flange.

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