Residual pressure recovery system and recovery and utilization method for pressure regulating system of oxygen production station

Abstract

The invention relates to an excess pressure recovery system and recycling method for a pressure regulating system of an oxygen production station, and the system comprises a nitrogen compression system which is communicated with an air separation system; the first recovery branch is communicated between the nitrogen compression system and a downstream medium-pressure nitrogen user; an inlet of the second recovery branch is communicated with the nitrogen compression system, and an outlet of the second recovery branch is communicated with a downstream low-pressure nitrogen user; the second recovery branch comprises a first branch and a second branch, and the first branch is provided with a residual pressure turbine power generation device and a heat exchanger; and a pressure regulating valve group capable of regulating nitrogen pressure is arranged on the second branch. The residual pressure turbine power generation device, the heat exchanger and the nitrogen delivery process of the air separation device are fused, pressure loss is reduced, and the energy and material utilization rate of the air separation device is increased; the cooling capacity in the expanded nitrogen is recycled, so that the cooling efficiency is improved; the electric energy demand and the production electricity consumption cost in the electricity consumption peak period are reduced, and the purposes of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of air separation equipment, and in particular to a residual pressure recovery system and a recycling method of a pressure regulating system of an oxygen production station. Background Art

[0002] Air separation equipment is an important equipment for large steel enterprises. The nitrogen produced by it is widely used as protective gas, sealing gas, power source, etc. It is an indispensable gas source in the steel smelting process. In order to meet the demand for nitrogen as protective gas and backup, large and medium-sized steel enterprises will have a certain scale of medium-pressure nitrogen. After the nitrogen separated from the air separation oxygen generator is pressurized by the medium-pressure nitrogen compressor unit, part of it is directly delivered to the downstream medium-pressure nitrogen users, and part of it is delivered to the downstream nitrogen users after being reduced in pressure by the pressure regulating valve group. In order to meet the demand for nitrogen as protective gas and backup, part of the low-pressure nitrogen comes from the low-pressure nitrogen compressor, and part of the low-pressure nitrogen is reduced from 2.5MPa medium-pressure nitrogen to 0.8MPa. The current method of reducing the pressure from 2.5MPa medium-pressure nitrogen to 0.8MPa low-pressure nitrogen is to use a pressure regulating valve to reduce the pressure, and this pressure difference is not used.

[0003] Prior art 1: Chinese patent CN 116222150 A, published on September 8, 2022, provides an air separation unit and a material recovery method including a nitrogen energy storage power generation device. The disadvantage of this scheme is that compared with the amount of medium-pressure nitrogen, the amount of nitrogen released in the air separation unit is small and intermittent. The nitrogen release pipes are distributed on each device, which makes collection more difficult and increases the collection cost. In addition, the pressure of the released nitrogen in the air separation unit is low, and it needs to be compressed by a nitrogen compressor before it can enter the subsequent process. The process flow is complicated and the investment is higher. Some energy will be wasted in the entire process, resulting in low power generation efficiency and reduced return on investment.

[0004] Prior art 2: Chinese patent CN 114135352 A, published on March 4, 2022, discloses an experimental system and operation method for residual pressure power generation of natural gas. The disadvantage of this scheme is that the process is only considered for use on natural gas transportation pipelines, and high-pressure buffer tanks and low-pressure storage tanks are added to the process equipment, and the cost increases accordingly. If used in the nitrogen pressure regulating system of the oxygen production station, the source of nitrogen is stable. The operation of the air separation unit can generate pressurized nitrogen, obtain an energy source, reduce equipment costs, and thus reap higher economic benefits.

[0005] As the nitrogen consumption of steel enterprises is gradually increasing, this means more energy waste. Considering the huge power consumption of air separation units and steel smelting, the inventor, based on many years of experience and practice in related industries, proposes a residual pressure recovery system and recycling method for the pressure regulating system of an oxygen production station to overcome the defects of the prior art. Summary of the invention

[0006] The purpose of the present invention is to provide a surplus pressure recovery system and a recycling method for a pressure regulating system of an oxygen production station, which integrates a surplus pressure turbine power generation device, a heat exchanger and a nitrogen delivery process of an air separation device, which can not only reduce pressure loss and improve the energy and material utilization rate of the air separation device, but also recover and reuse the cold in the expanded nitrogen to improve cooling efficiency; reduce the power demand and production power cost during the peak power consumption period, and achieve the purpose of energy saving and emission reduction.

[0007] The object of the present invention is achieved by providing a residual pressure recovery system for a pressure regulating system of an oxygen production station, comprising:

[0008] a nitrogen compression system, connected to the air separation system, for compressing nitrogen extracted from the air separation system;

[0009] A first recovery branch connected between the nitrogen compression system and a downstream medium-pressure nitrogen user;

[0010] A second recovery branch, the inlet of the second recovery branch is connected to the nitrogen compression system, and the outlet of the second recovery branch is connected to a downstream low-pressure nitrogen user; the second recovery branch includes a first branch and a second branch arranged in parallel, a residual pressure turbine power generation device capable of generating electricity using medium-pressure nitrogen and a heat exchanger capable of exchanging heat with the nitrogen flowing out of the residual pressure turbine power generation device are sequentially arranged on the first branch; a pressure regulating valve group capable of adjusting the nitrogen pressure is arranged on the second branch.

[0011] In a preferred embodiment of the present invention, the excess pressure turbine power generation device includes a turbine expander and a generator. The medium-pressure nitrogen compressed by the nitrogen compression system can enter the turbine expander to expand and perform work to drive the generator to generate electricity. The electricity generated by the generator is used to supply power facilities.

[0012] In a preferred embodiment of the present invention, a first heat exchange passage and a second heat exchange passage are provided in the heat exchanger, the inlet of the first heat exchange passage is connected to the outlet of the turbine expander, and the outlet of the first heat exchange passage is connected to a downstream low-pressure nitrogen user; the second heat exchange passage is connected to a circulating water main in a circulation manner, and the low-temperature nitrogen formed after the medium-pressure nitrogen in the turbine expander does work enters the first heat exchange passage to exchange heat with the circulating water in the second heat exchange passage.

[0013] In a preferred embodiment of the present invention, a shut-off valve and a first pressure monitoring device are provided at the inlet of the turbine expander; the turbine expander is interlockedly controlled with the shut-off valve.

[0014] In a preferred embodiment of the present invention, a stop valve, a second pressure monitoring device and a first temperature monitoring device are provided at the outlet of the turbo expander.

[0015] In a preferred embodiment of the present invention, a second temperature monitoring device is provided at the outlet of the first heat exchange passage, and a third temperature monitoring device is provided at the outlet of the second heat exchange passage.

[0016] In a preferred embodiment of the present invention, a third pressure monitoring device is provided at the inlet of the second recovery branch, and a fourth pressure monitoring device and a flow meter are provided at the outlet of the second recovery branch.

[0017] In a preferred embodiment of the present invention, the outlet of the nitrogen compression system is provided with a nitrogen gas tank, which is used to store nitrogen and can buffer peak loads.

[0018] The object of the present invention can also be achieved in this way. A method for recovering and utilizing the residual pressure of a pressure regulating system of an oxygen production station is provided. The residual pressure recovery system of the pressure regulating system of the oxygen production station is connected to an air separation system. The nitrogen extracted from the air separation system is compressed by a nitrogen compression system to form medium-pressure nitrogen. The medium-pressure nitrogen is divided into two paths. The first path is connected to a downstream medium-pressure nitrogen user via a first recovery branch. The second path is connected to a downstream low-pressure nitrogen user via a residual pressure turbine power generation device or a pressure regulating valve group. Under normal circumstances, the medium-pressure nitrogen of the second path enters the turbine expander on the first branch path to expand and perform work to drive a generator to generate electricity. The electricity generated by the generator is used to supply power facilities. The low-temperature nitrogen formed after the work is heated by heat exchange and flows to the downstream low-pressure nitrogen user. When the residual pressure turbine power generation device fails, the first branch path is cut off. The medium-pressure nitrogen of the second path is directly connected to the downstream low-pressure nitrogen user after pressure regulation by the pressure regulating valve group of the second branch path.

[0019] In a preferred embodiment of the present invention, the low-temperature nitrogen formed after expansion work in the turbine expander flows to the first heat exchange path of the heat exchanger, exchanges heat with the circulating water in the second heat exchange path of the heat exchanger, and the low-temperature nitrogen in the first heat exchange path is reheated and heated up and flows to the downstream low-pressure nitrogen user; the circulating water in the second heat exchange path is cooled and flows to the cold water application device.

[0020] As described above, the residual pressure recovery system and recycling method of the oxygen production station pressure regulating system of the present invention have the following advantages:

[0021] Beneficial effects:

[0022] In the present invention, the residual pressure turbine power generation device is integrated with the nitrogen delivery process of the air separation unit, and the pressure energy of nitrogen is used to generate electric energy, thereby reducing the demand for electric energy during the peak period of electricity consumption, reducing the electricity cost of the steel plant production, and achieving the purpose of energy conservation and emission reduction; the energy conversion inside the air separation unit is realized by the residual pressure turbine power generation device, without the need for external equipment and energy;

[0023] Through heat exchange in the heat exchanger, the cooling capacity of the expanded nitrogen is fully utilized to reduce the circulating water temperature, reach the cooling water temperature required by the compressor process, and improve the cooling efficiency;

[0024] The present invention can adjust the nitrogen pressure and can replace the existing pressure regulating valve group to reduce pressure during operation;

[0025] The present invention makes full use of the surplus pressure in the pressure regulating system of the oxygen production station, recycles the nitrogen pressure of the pressure regulating system in the oxygen production station, recycles the released energy, reduces the pressure loss, and improves the energy and material utilization rate of the air separation device;

[0026] The residual pressure turbine power generation device used in the present invention is mature in development, has controllable cost, a short investment payback period, and has considerable economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The following drawings are only intended to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0028] in:

[0029] Figure 1 : It is a schematic diagram of the residual pressure recovery system of the oxygen production station pressure regulating system of the present invention.

[0030] In the figure:

[0031] 1. The first recovery branch;

[0032] 2. Second recovery branch road; 21. First branch road; 22. Second branch road;

[0033] 3. Nitrogen compression system; 31. Nitrogen balloon tank;

[0034] 4. Excess pressure turbine power generation device; 41. Turbine expander; 42. Generator; 421. Factory lighting; 422. Circulating water pump; 423. Air conditioning;

[0035] 5. Heat exchanger;

[0036] 6. Pressure regulating valve group;

[0037] 7. Circulating water main pipe; 71. Air compressor water supply pipe; 72. Oxygen compressor water supply pipe; 73. Nitrogen compressor water supply;

[0038] 81. Shut-off valve; 821. First pressure monitoring device; 822. Second pressure monitoring device; 823. Third pressure monitoring device; 824. Fourth pressure monitoring device; 83. Shut-off valve; 841. First temperature monitoring device; 842. Second temperature monitoring device; 843. Third temperature monitoring device; 85. Flow meter;

[0039] 91. Downstream medium-pressure nitrogen users; 92. Downstream low-pressure nitrogen users; 93. Air separation system. DETAILED DESCRIPTION

[0040] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0041] The specific embodiments of the present invention described herein are only used to explain the purpose of the present invention and cannot be understood as limiting the present invention in any way. Under the guidance of the present invention, technicians can conceive of any possible variations based on the present invention, which should be considered to belong to the scope of the present invention. It should be noted that when an element is referred to as "arranged on" another element, it can be directly on the other element or there can also be a central element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be a central element at the same time. The terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a mechanical connection or an electrical connection, or it can be the internal communication of two elements, it can be directly connected, or it can be indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "vertical", "horizontal", "up", "down", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only implementation method.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0043] like Figure 1 As shown, the present invention provides a residual pressure recovery system of a pressure regulating system of an oxygen production station, comprising:

[0044] A nitrogen compression system 3, which is connected to the air separation system, is used to compress the nitrogen extracted from the air separation system 93 (air separation unit) to form medium-pressure nitrogen (pressure range 2.0-3.0 MPa);

[0045] The first recovery branch 1 is connected between the nitrogen compression system 3 and the downstream medium-pressure nitrogen user 91;

[0046] A second recovery branch 2, the inlet of which is connected to a nitrogen compression system 3, and the outlet of which is connected to a downstream low-pressure nitrogen user 92 (the pressure range of the low-pressure nitrogen is 0.8 to 1.0 MPa); the second recovery branch 2 comprises a first branch 21 and a second branch 22 which are arranged in parallel, a residual pressure turbine power generation device 4 and a heat exchanger 5 are arranged in sequence on the first branch 21, the residual pressure turbine power generation device 4 is used to generate electricity using medium-pressure nitrogen to supply electric energy to the electric facilities; the heat exchanger 5 is used to exchange heat with the nitrogen flowing out of the residual pressure turbine power generation device 4; a pressure regulating valve group 6 is arranged on the second branch 22, the pressure regulating valve group 6 is used to adjust the nitrogen pressure of the second branch 22, and when the residual pressure turbine power generation device 4 fails, the nitrogen pressure is adjusted by the pressure regulating valve group 6 and then supplied to the downstream low-pressure nitrogen user 92.

[0047] The air separation unit is an important basic equipment in the field of industrial production and an essential equipment in large steel enterprises. It accounts for a certain proportion of the electricity consumption of the entire steel plant. Considering the huge electricity consumption of the air separation unit and steel smelting, and the fact that part of the low-pressure nitrogen in the steel plant is reduced from the medium-pressure nitrogen, and this pressure difference is not utilized. The present invention can recycle the nitrogen pressure

[0048] In the residual pressure recovery system of the oxygen production station pressure regulating system of the present invention, the residual pressure turbine power generation device 4 is integrated with the nitrogen delivery process of the air separation unit, and the pressure energy of nitrogen is used to generate electric energy, thereby reducing the demand for electric energy during the peak period of electricity consumption, reducing the production electricity cost of the steel plant, and achieving the purpose of energy conservation and emission reduction; the energy conversion inside the air separation unit is realized by the residual pressure turbine power generation device 4, without the need for external equipment and energy;

[0049] By exchanging heat with the heat exchanger, the cooling capacity of the expanded nitrogen is fully utilized to reduce the circulating water temperature, reach the cooling water temperature required by the compressor process, and improve the cooling efficiency;

[0050] The present invention can adjust the nitrogen pressure and can replace the existing pressure regulating valve group to reduce pressure during operation;

[0051] The present invention makes full use of the surplus pressure in the pressure regulating system of the oxygen production station, recycles the nitrogen pressure of the pressure regulating system in the oxygen production station, recycles the released energy, reduces pressure loss, and improves the energy and material utilization rate of the air separation unit; the waste pressure turbine power generation device used in the present invention is mature, cost-controllable, and has a short investment recovery period, and has considerable economic benefits.

[0052] Further, if Figure 1As shown, the residual pressure turbine power generation device 4 includes a turbine expander 41 and a generator 42. The medium-pressure nitrogen compressed by the nitrogen compression system can enter the turbine expander 41 to expand and drive the generator 42 to generate electricity. The electricity generated by the generator 42 is used to supply power facilities, which are auxiliary power facilities in the factory, such as factory lighting 421 (street lights), circulating water pumps 422 and air conditioners 423 (distribution room air conditioners).

[0053] Further, if Figure 1 As shown, a cut-off valve 81 and a first pressure monitoring device 821 are provided at the inlet of the turbine expander 41; the turbine expander 41 is interlocked with the cut-off valve 81. On the second recovery branch 2, the cut-off valve 81 is in a normally open state; when the residual pressure turbine power generation device 4 fails, the cut-off valve 81 can be interlocked and controlled to be quickly cut off, and the medium-pressure nitrogen is directly supplied to the outside after being regulated by the pressure regulating valve group 6, which will not affect the subsequent low-pressure nitrogen users.

[0054] Further, if Figure 1 As shown, a stop valve 83 , a second pressure monitoring device 822 and a first temperature monitoring device 841 are provided at the outlet of the turbo expander 41 .

[0055] Further, if Figure 1 As shown, a heat exchanger 5 is arranged on the first branch road 21, and the heat exchanger 5 can adopt a tube-fin heat exchanger; a first heat exchange passage and a second heat exchange passage are arranged in the heat exchanger 5, the inlet of the first heat exchange passage is connected with the outlet of the turbine expander 41, and the outlet of the first heat exchange passage is connected with the downstream low-pressure nitrogen user 92; the second heat exchange passage is connected with the circulating water main pipe 7 in a circulation manner, and the low-temperature nitrogen formed after the medium-pressure nitrogen in the turbine expander 41 does work enters the first heat exchange passage and exchanges heat with the circulating water in the second heat exchange passage.

[0056] Further, if Figure 1 As shown, a second temperature monitoring device 842 is provided at the outlet of the first heat exchange passage, and a third temperature monitoring device 843 is provided at the outlet of the second heat exchange passage.

[0057] The nitrogen coming out of the turbine expander 41 reduces its internal energy and lowers its temperature after doing work to form low-temperature nitrogen (temperature range -40 to -60°C). The low-temperature nitrogen coming out of the turbine expander 41 (temperature detected by the first temperature monitoring device 841) is connected to the circulating water main pipe 7 through the heat exchanger 5 (tube-fin heat exchanger) to adjust the temperature, which can not only reheat the low-temperature nitrogen to room temperature, but also transfer the coldness of the low-temperature nitrogen to the circulating water to cool it down. The reheated nitrogen passes through the second temperature monitoring device 842, and after confirming that it has been reheated to room temperature, it is sent to the downstream low-pressure nitrogen user 92. The cooling water returned to the circulating water main pipe 7 is monitored by the third temperature monitoring device 843. The cooled circulating water can be supplied to a series of devices in the air separation unit that need cold water, such as the air compressor water supply pipe, the oxygen compressor water supply pipe, and the nitrogen compressor water supply pipe. The low-temperature nitrogen is connected to the circulating water main pipe 7 through the heat exchanger 5 to adjust the temperature, so that the circulating water can be cooled and the cooling efficiency can be improved. The low-temperature nitrogen coming out of the residual pressure turbine power generation device 4 is reheated to room temperature before being transported to the downstream low-pressure nitrogen user 92 (low-pressure nitrogen user pipeline network), which reduces the impact on the pipeline network and does not affect the downstream nitrogen users.

[0058] The heat exchange effect can be monitored by the first temperature monitoring device 841, the second temperature monitoring device 842, and the third temperature monitoring device 843 to ensure that the temperature of the gas entering the low-pressure nitrogen pipeline network is at room temperature and does not cause any impact on the pipeline network.

[0059] Further, if Figure 1 As shown, a third pressure monitoring device 823 is provided at the inlet of the second recovery branch 2, and a fourth pressure monitoring device 824 and a flow meter 85 are provided at the outlet of the second recovery branch.

[0060] Further, if Figure 1 As shown, a nitrogen gas ball tank 31 is provided at the outlet of the nitrogen compression system 3, and surplus nitrogen is stored in the nitrogen gas ball tank 31, which plays a role of buffering and peak regulation.

[0061] The present invention also provides a method for recycling the excess pressure of a pressure regulating system of an oxygen production station, wherein the excess pressure recovery system of the pressure regulating system of the oxygen production station is connected to an air separation system 93, and the nitrogen extracted from the air separation system 93 is compressed by a nitrogen compression system 3 to form medium-pressure nitrogen. The medium-pressure nitrogen is divided into two paths, the first path is connected (directly connected) to a downstream medium-pressure nitrogen user 91 via a first recovery branch 1; the second path is connected to a downstream low-pressure nitrogen user 92 via a excess pressure turbine power generation device 4 or a pressure regulating valve group 6.

[0062] Under normal conditions, the shut-off valve 81 is in a normally open state, and the medium-pressure nitrogen enters the residual-pressure turbine power generation device 4, that is, enters the turbine expander 41 on the first branch line 21 to expand and work to drive the generator 42 to generate electricity. The electricity generated by the generator 42 is used to supply power facilities, and the low-temperature nitrogen formed after work is heated by heat exchange and flows to the downstream low-pressure nitrogen user 92;

[0063] When the residual pressure turbine power generation device 4 fails, the first branch line 21 is cut off (the first pressure monitoring device 821 can interlock and control the cut-off valve 81 to quickly cut it off), and the medium-pressure nitrogen is directly connected to the downstream low-pressure nitrogen user 92 after pressure regulation by the pressure regulating valve group 6 of the second branch line 22.

[0064] The low-temperature nitrogen formed after expansion work in the turbine expander 41 flows to the first heat exchange path of the heat exchanger 5, and exchanges heat with the circulating water in the second heat exchange path of the heat exchanger 5. The low-temperature nitrogen in the first heat exchange path is reheated and heated up and flows to the downstream low-pressure nitrogen user 92; the circulating water in the second heat exchange path is cooled and flows to the cold water application device, the specific location:

[0065] The nitrogen coming out of the turbine expander 41 is converted into low-temperature nitrogen after its internal energy is reduced and its temperature is lowered after doing work externally. The low-temperature nitrogen coming out of the turbine expander 41 (the temperature is detected by the first temperature monitoring device 841) is connected to the circulating water main pipe 7 through the heat exchanger 5 (tube-fin heat exchanger) to adjust the temperature mutually, which can not only reheat the low-temperature nitrogen to room temperature, but also transfer the coldness of the low-temperature nitrogen to the circulating water to cool it down. The reheated nitrogen passes through the second temperature monitoring device 842, and after confirming that it has been reheated to room temperature, it is sent to the downstream low-pressure nitrogen user 92. The cooling water returned to the circulating water main pipe 7 is monitored by the third temperature monitoring device 843 for temperature. The cooled circulating water can be supplied to a series of devices in the air separation unit that need cold water, such as the air compressor water supply pipe 71, the oxygen compressor water supply pipe 72, and the nitrogen compressor water supply 73.

[0066] As described above, the residual pressure recovery system and recycling method of the oxygen production station pressure regulating system of the present invention have the following advantages:

[0067] Beneficial effects:

[0068] In the present invention, the residual pressure turbine power generation device is integrated with the nitrogen delivery process of the air separation unit, and the pressure energy of nitrogen is used to generate electric energy, thereby reducing the demand for electric energy during the peak period of electricity consumption, reducing the electricity cost of the steel plant production, and achieving the purpose of energy conservation and emission reduction; the energy conversion inside the air separation unit is realized by the residual pressure turbine power generation device, without the need for external equipment and energy;

[0069] Through heat exchange in the heat exchanger, the cooling capacity of the expanded nitrogen is fully utilized to reduce the circulating water temperature, reach the cooling water temperature required by the compressor process, and improve the cooling efficiency;

[0070] The present invention can adjust the nitrogen pressure and can replace the existing pressure regulating valve group to reduce pressure during operation;

[0071] The present invention makes full use of the surplus pressure in the pressure regulating system of the oxygen production station, recycles the nitrogen pressure of the pressure regulating system in the oxygen production station, recycles the released energy, reduces the pressure loss, and improves the energy and material utilization rate of the air separation device;

[0072] The residual pressure turbine power generation device used in the present invention is mature in development, has controllable cost, a short investment payback period, and has considerable economic benefits.

[0073] The above description is only an illustrative embodiment of the present invention and is not intended to limit the scope of the present invention. Any equivalent changes and modifications made by any person skilled in the art without departing from the concept and principle of the present invention shall fall within the scope of protection of the present invention.

Claims

1. An oxygen production station pressure regulating system residual pressure recovery system, characterized in that: include, a nitrogen compression system, connected to the air separation system, for compressing nitrogen extracted from the air separation system; A first recovery branch connected between the nitrogen compression system and a downstream medium-pressure nitrogen user; A second recovery branch, the inlet of the second recovery branch is connected to the nitrogen compression system, and the outlet of the second recovery branch is connected to a downstream low-pressure nitrogen user; the second recovery branch includes a first branch and a second branch arranged in parallel, a residual pressure turbine power generation device capable of generating electricity using medium-pressure nitrogen and a heat exchanger capable of exchanging heat with the nitrogen flowing out of the residual pressure turbine power generation device are sequentially arranged on the first branch; a pressure regulating valve group capable of adjusting the nitrogen pressure is arranged on the second branch.

2. The residual pressure recovery system of the oxygen production station pressure regulating system according to claim 1, characterized in that: The residual pressure turbine power generation device includes a turbine expander and a generator. The medium-pressure nitrogen compressed by the nitrogen compression system can enter the turbine expander to expand and perform work to drive the generator to generate electricity. The electricity generated by the generator is used to supply power facilities.

3. The residual pressure recovery system of the pressure regulating system of the oxygen production station according to claim 2, characterized in that: A first heat exchange passage and a second heat exchange passage are provided in the heat exchanger, wherein the inlet of the first heat exchange passage is connected to the outlet of the turbine expander, and the outlet of the first heat exchange passage is connected to a downstream low-pressure nitrogen user; the second heat exchange passage is in circulation communication with the circulating water main pipe, and the low-temperature nitrogen formed after the medium-pressure nitrogen in the turbine expander does work enters the first heat exchange passage for heat exchange with the circulating water in the second heat exchange passage.

4. The residual pressure recovery system of the pressure regulating system of the oxygen production station according to claim 2, characterized in that: A cut-off valve and a first pressure monitoring device are arranged at the inlet of the turbine expander; the turbine expander is interlockedly controlled with the cut-off valve.

5. The residual pressure recovery system of the pressure regulating system of the oxygen production station according to claim 2, characterized in that: The outlet of the turbo expander is provided with a stop valve, a second pressure monitoring device and a first temperature monitoring device.

6. The residual pressure recovery system of the pressure regulating system of the oxygen production station according to claim 3, characterized in that: A second temperature monitoring device is provided at the outlet of the first heat exchange passage, and a third temperature monitoring device is provided at the outlet of the second heat exchange passage.

7. The residual pressure recovery system of the pressure regulating system of the oxygen production station according to claim 3, characterized in that: A third pressure monitoring device is provided at the inlet of the second recovery branch, and a fourth pressure monitoring device and a flow meter are provided at the outlet of the second recovery branch.

8. The residual pressure recovery system of the pressure regulating system of the oxygen production station according to claim 1, characterized in that: The outlet of the nitrogen compression system is provided with a nitrogen gas tank, which is used to store nitrogen and can buffer and shave peak.

9. A method for recovering excess pressure in a pressure regulating system of an oxygen production station, characterized in that: The residual pressure recovery system of the pressure regulating system of the oxygen production station according to any one of claims 1 to 8 is connected to the air separation system, and the nitrogen extracted from the air separation system is compressed by the nitrogen compression system to form medium-pressure nitrogen. The medium-pressure nitrogen is divided into two paths, the first path is connected to the downstream medium-pressure nitrogen user through the first recovery branch; the second path is connected to the downstream low-pressure nitrogen user through the residual pressure turbine power generation device or the pressure regulating valve group; under normal circumstances, the medium-pressure nitrogen of the second path enters the turbine expander on the first branch road to expand and do work to drive the generator to generate electricity, and the electricity generated by the generator is used to supply power facilities, and the low-temperature nitrogen formed after the work is heated by heat exchange and flows to the downstream low-pressure nitrogen user; when the residual pressure turbine power generation device fails, the first branch road is cut off, and the medium-pressure nitrogen of the second path is directly connected to the downstream low-pressure nitrogen user after pressure regulation by the pressure regulating valve group of the second branch road.

10. The method for recovering excess pressure of a pressure regulating system of an oxygen production station according to claim 9, characterized in that: The low-temperature nitrogen formed after expansion work in the turbine expander flows to the first heat exchange path of the heat exchanger, exchanges heat with the circulating water in the second heat exchange path of the heat exchanger, and the low-temperature nitrogen in the first heat exchange path is reheated and heated up before flowing to the downstream low-pressure nitrogen user; the circulating water in the second heat exchange path is cooled and flows to the cold water application device.

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