A method for controlling medium and low pressure nitrogen connecting valves in an oxygen production system

Abstract

The present invention discloses a method for controlling a medium- and low-pressure nitrogen interconnecting valve of an oxygen production system, and relates to the field of pressure control technology. The method comprises: obtaining a medium-pressure pressure value of a medium-pressure nitrogen pipeline network of an oxygen production system and a low-pressure pressure value of a low-pressure nitrogen pipeline network; determining a target regulating loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulating loop according to the medium-pressure pressure value and / or the low-pressure pressure value; calculating a target opening angle of the medium- and low-pressure nitrogen interconnecting valve; using a preset switch amplitude value to adjust the medium- and low-pressure nitrogen interconnecting valve to the target opening angle, so that the pressure of the medium-pressure nitrogen pipeline network is maintained in a first pressure interval, and the low-pressure nitrogen pipeline network is maintained in a second pressure interval. Through the above method, the first is to improve the pressure stability of the low-pressure nitrogen pipeline network, and the second is to reduce the number of times the medium-pressure nitrogen pipeline network is released due to excessive pressure, thereby increasing the service life of the medium-pressure nitrogen compressor and reducing resource waste.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure control, and in particular to a method for controlling medium- and low-pressure nitrogen connecting valves in an oxygen production system. Background Art

[0002] The oxygen production system may include a medium-pressure nitrogen compressor, a medium-pressure nitrogen pipeline network and a low-pressure nitrogen pipeline network. The pressure of the medium-pressure nitrogen pipeline network is generally controlled at 1.4-1.8MPa. When the pressure of the medium-pressure nitrogen pipeline network is higher than 1.82MPa, the medium-pressure nitrogen pipeline network opens the vent valve to release the pressure to reduce the pressure in the pipeline network; the pressure of the low-pressure nitrogen pipeline network is generally controlled at 0.4MPa-0.6MPa, which is mainly used to ensure the stability of the instrument gas source and the pressure stability of long-distance low-pressure nitrogen users.

[0003] All medium-pressure nitrogen compressors are load-automatically controlled air compressors, which are stopped and started according to the release of the medium-pressure nitrogen network, that is, the medium-pressure nitrogen compressor stops working when the medium-pressure nitrogen network is released, and starts working when the medium-pressure nitrogen network is not released. Since the pressure of the medium-pressure nitrogen network fluctuates greatly due to the impact of the slag splashing of the double-blowing converter, the frequent release operation will reduce the service life of the medium-pressure nitrogen compressor, and the release operation will cause a huge waste of resources. Summary of the invention

[0004] The purpose of the present invention is to solve the above-mentioned problems of the background technology and to provide a method for controlling a medium- and low-pressure nitrogen connecting valve of an oxygen production system.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] An embodiment of the present invention provides a method for controlling a medium- and low-pressure nitrogen connecting valve of an oxygen production system, the method comprising:

[0007] Obtaining a medium pressure value of a medium pressure nitrogen pipeline network and a low pressure value of a low pressure nitrogen pipeline network of an oxygen production system; the normal operating pressures of the medium pressure nitrogen pipeline network and the low pressure nitrogen pipeline network are respectively a first pressure range and a second pressure range;

[0008] Determining a target regulating loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulating loop according to the medium-pressure pressure value and / or the low-pressure pressure value;

[0009] Calculating a target opening angle of a medium- and low-pressure nitrogen connecting valve according to the target regulating loop, the medium-pressure value and the low-pressure value;

[0010] The medium- and low-pressure nitrogen connecting valve is adjusted to the target opening angle using a preset switching amplitude value, so that the pressure of the medium-pressure nitrogen pipeline network is maintained in the first pressure range, and the low-pressure nitrogen pipeline network is maintained in the second pressure range.

[0011] Optionally, the preset regulating loop includes a first regulating loop and a second regulating loop, a first preset value of the first regulating loop is higher than a second preset value of the second regulating loop, and the first preset value and the second preset value are target values ​​for the first regulating loop and the second regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network, respectively;

[0012] Determining a target regulating loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulating loop according to the medium-pressure pressure value includes:

[0013] Determine the relationship between the medium pressure value and a third pressure range preset for the medium pressure nitrogen pipeline network, and determine a target regulation loop; the third pressure range is included in the first pressure range;

[0014] If the medium pressure value is greater than or equal to the maximum value of the third pressure interval, selecting the first regulating loop as the target regulating loop;

[0015] If the medium pressure value is less than or equal to the minimum value of the third pressure interval, the second regulating loop is selected as the target regulating loop.

[0016] Optionally, the preset regulating loop includes a third regulating loop and a fourth regulating loop, the third preset value of the third regulating loop is higher than the fourth preset value of the fourth regulating loop, and the third preset value and the fourth preset value are target values ​​for the third regulating loop and the fourth regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network, respectively;

[0017] Determining a target regulation loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulation loop according to the low-pressure pressure value includes:

[0018] Determine the relationship between the low pressure value and a fourth pressure interval preset for the low pressure nitrogen pipeline network, and determine a target regulation loop; the fourth pressure interval is included in the second pressure interval;

[0019] If the low pressure value is greater than or equal to the maximum value of the fourth pressure interval, selecting the fourth regulating loop as the target regulating loop;

[0020] If the low pressure value is less than or equal to the minimum value of the fourth pressure interval, the third regulating loop is selected as the target regulating loop.

[0021] Optionally, the preset regulating loop includes a fifth regulating loop, a sixth regulating loop, a seventh regulating loop and an eighth regulating loop, the fifth preset value of the fifth regulating loop, the sixth preset value of the sixth regulating loop, the seventh preset value of the seventh regulating loop and the eighth preset value of the eighth regulating loop are decreased in sequence, and the fifth preset value, the sixth preset value, the seventh preset value and the eighth preset value are respectively the target values ​​for the fifth regulating loop, the sixth regulating loop, the seventh regulating loop and the eighth regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network;

[0022] Determining a target regulation loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulation loop according to the medium-pressure pressure value and the low-pressure pressure value includes:

[0023] Determine the relationship between the medium pressure value and the fifth pressure interval preset for the medium pressure nitrogen pipeline network, determine the relationship between the low pressure value and the sixth pressure interval preset for the low pressure nitrogen pipeline network, and determine the target regulation loop; the fifth pressure interval is included in the first pressure interval; the sixth pressure interval is included in the second pressure interval;

[0024] If the medium pressure value is greater than or equal to the maximum value of the fifth pressure interval, and the low pressure value is less than or equal to the minimum value of the sixth pressure interval, then the fifth regulation loop is selected as the target regulation loop;

[0025] If the medium pressure value is greater than or equal to the maximum value of the fifth pressure interval, and the low pressure value is greater than or equal to the minimum value of the sixth pressure interval, then the sixth regulation loop is selected as the target regulation loop;

[0026] If the medium pressure value is less than or equal to the minimum value of the fifth pressure interval, and the low pressure value is less than or equal to the maximum value of the sixth pressure interval, the seventh regulation loop is selected as the target regulation loop.

[0027] If the medium pressure value is less than or equal to the minimum value of the fifth pressure interval, and the low pressure value is greater than or equal to the maximum value of the sixth pressure interval, the eighth regulation loop is selected as the target regulation loop.

[0028] Optionally, the method further comprises:

[0029] When the low pressure value is greater than or equal to the maximum value of the second pressure range, the medium and low pressure nitrogen connecting valve is closed.

[0030] Optionally, the method further comprises:

[0031] When the medium pressure value is greater than or equal to a preset relief pressure value, the medium pressure nitrogen pipeline opens the relief valve to perform a relief operation; the preset relief pressure value is greater than the maximum value of the first pressure range.

[0032] An embodiment of the present invention provides a method for controlling a medium- and low-pressure nitrogen interconnecting valve of an oxygen production system, the method comprising: obtaining a medium-pressure value of a medium-pressure nitrogen pipeline network and a low-pressure value of a low-pressure nitrogen pipeline network of the oxygen production system; the normal working pressures of the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network are respectively a first pressure interval and a second pressure interval; according to the medium-pressure value and / or the low-pressure value, determining a target regulating loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulating loop; according to the target regulating loop, the medium-pressure value and the low-pressure value, calculating a target opening angle of the medium- and low-pressure nitrogen interconnecting valve; and using a preset switching amplitude value to adjust the medium- and low-pressure nitrogen interconnecting valve to the target opening angle, so that the pressure of the medium-pressure nitrogen pipeline network is maintained in the first pressure interval, and the pressure of the low-pressure nitrogen pipeline network is maintained in the second pressure interval. Through the regulation and control of the medium- and low-pressure nitrogen connecting valve, nitrogen can be transported to the low-pressure nitrogen network through the medium-pressure nitrogen network. The low-pressure nitrogen compressor increases or decreases the load according to the pressure of the low-pressure nitrogen network. The first is to improve the pressure stability of the low-pressure nitrogen network, and the second is to reduce the number of times the medium-pressure nitrogen network is released due to excessive pressure. The service life of the medium-pressure nitrogen compressor is increased and resource waste is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below in conjunction with the accompanying drawings.

[0034] Figure 1 A method for controlling a medium- and low-pressure nitrogen connecting valve of an oxygen production system is provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] The embodiment of the present invention provides a method for controlling a medium- and low-pressure nitrogen connecting valve in an oxygen production system. Figure 1 , Figure 1 A method for controlling a medium- and low-pressure nitrogen connecting valve of an oxygen production system provided in an embodiment of the present invention may include the following steps:

[0037] S101, obtaining a medium pressure value of a medium pressure nitrogen pipeline network and a low pressure value of a low pressure nitrogen pipeline network of an oxygen production system.

[0038] S102, determining a target regulating loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulating loop according to the medium-pressure value and / or the low-pressure value.

[0039] S103, calculating the target opening angle of the medium- and low-pressure nitrogen connecting valve according to the target regulation loop, the medium-pressure value and the low-pressure value.

[0040] S104, using a preset switching amplitude value to adjust the medium- and low-pressure nitrogen connecting valve to a target opening angle, so that the pressure of the medium-pressure nitrogen pipeline network is maintained in a first pressure range, and the pressure of the low-pressure nitrogen pipeline network is maintained in a second pressure range.

[0041] The normal operating pressures of the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network are respectively the first pressure range and the second pressure range.

[0042] Based on the control method of the medium- and low-pressure nitrogen interconnecting valve of an oxygen production system provided by the embodiment of the present invention, the medium- and low-pressure nitrogen interconnecting valve can be adjusted and controlled to supplement nitrogen delivery to the low-pressure nitrogen pipeline network through the medium-pressure nitrogen pipeline network, and the low-pressure nitrogen compressor increases or decreases the load according to the pressure of the low-pressure nitrogen pipeline network. The first is to improve the pressure stability of the low-pressure nitrogen pipeline network, and the second is to reduce the number of times the medium-pressure nitrogen pipeline network is released due to excessive pressure. The service life of the medium-pressure nitrogen compressor is increased and resource waste is reduced.

[0043] In one implementation, the preset switching amplitude value may include the opening amplitude value and the closing amplitude value of the medium and low pressure nitrogen interconnecting valve. The medium and low pressure nitrogen interconnecting valve is adjusted to the target opening angle using the preset switching amplitude value, so as to achieve the purpose of super pool slope control of the medium and low pressure nitrogen interconnecting valve, so that the medium and low pressure nitrogen interconnecting valve is switched to open or close according to the preset switching amplitude value, reducing the impact of the gas in the pipeline network on the valve pipeline network and equipment, and also ensuring the normal safe production under extreme process conditions.

[0044] In one implementation, a ramp controller can be used to control the opening and closing operations of the medium and low pressure nitrogen connecting valves. The ramp controller can receive a preset switching amplitude value and a target opening angle, and use the preset switching amplitude value to adjust the medium and low pressure nitrogen connecting valves to the target opening angle.

[0045] When opening the valve, the target valve opening = target opening angle = current opening + n*M

[0046] When closing the valve, the target valve opening = target opening angle = current opening - n*M

[0047] Among them, n is the number of execution cycles of the controller, and M is the opening and closing amplitude of the medium and low pressure nitrogen connecting valve in each cycle (which can be set by technical personnel), that is, the current opening of the valve gradually approaches the target opening angle after n execution cycles.

[0048] In one embodiment, the target opening angle may also be set by a technician based on experience.

[0049] In one embodiment, the preset regulating loop includes a first regulating loop and a second regulating loop, the first preset value of the first regulating loop is higher than the second preset value of the second regulating loop, and the first preset value and the second preset value are target values ​​for the first regulating loop and the second regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network respectively;

[0050] According to the medium pressure value, the target regulation loop between the medium pressure nitrogen network and the low pressure nitrogen network is determined in the preset regulation loop, including:

[0051] Determine the relationship between the medium pressure value and a third pressure interval preset in the medium pressure nitrogen pipeline network, and determine the target regulation loop; the third pressure interval is included in the first pressure interval;

[0052] If the medium pressure value is greater than or equal to the maximum value of the third pressure interval, the first regulating loop is selected as the target regulating loop;

[0053] If the medium pressure value is less than or equal to the minimum value of the third pressure interval, the second regulating loop is selected as the target regulating loop.

[0054] In one implementation, if the medium pressure value is within the third pressure range, the medium and low pressure nitrogen connecting valve maintains the current opening.

[0055] In one implementation, when the medium pressure value is greater than or equal to the maximum value of the third pressure interval, the medium-pressure nitrogen pipeline network pressure is relatively high. The medium- and low-pressure nitrogen valves can be opened to a greater extent to send gas to the low-pressure nitrogen pipeline network as much as possible. The low-pressure nitrogen pipeline network pressure can be set to be slightly higher. Therefore, the first regulation loop is selected to regulate the low-pressure nitrogen pipeline network with the first preset value.

[0056] When the medium pressure value is less than or equal to the minimum value of the third pressure interval, the medium-pressure nitrogen pipeline network pressure is low. Gas should be supplied to the low-pressure nitrogen pipeline network while ensuring the stability of the medium-pressure nitrogen pipeline network pressure. The medium and low-pressure nitrogen valves should be opened to a smaller extent, and the low-pressure nitrogen pipeline network pressure can be set to a smaller level. Therefore, the second regulation loop is selected to regulate the low-pressure nitrogen pipeline network with the second preset value.

[0057] In one embodiment, the preset regulating loop includes a third regulating loop and a fourth regulating loop, the third preset value of the third regulating loop is higher than the fourth preset value of the fourth regulating loop, and the third preset value and the fourth preset value are target values ​​for the third regulating loop and the fourth regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network, respectively;

[0058] According to the low pressure value, the target regulating loop between the medium pressure nitrogen network and the low pressure nitrogen network is determined in the preset regulating loop, including:

[0059] Determine the relationship between the low pressure value and a fourth pressure interval preset in the low pressure nitrogen pipeline network, and determine the target regulation loop; the fourth pressure interval is included in the second pressure interval;

[0060] If the low pressure value is greater than or equal to the maximum value of the fourth pressure interval, the fourth regulating loop is selected as the target regulating loop;

[0061] If the low pressure value is less than or equal to the minimum value of the fourth pressure interval, the third regulating loop is selected as the target regulating loop.

[0062] In one implementation, if the low pressure value is within the fourth pressure interval, the medium and low pressure nitrogen connecting valve maintains the current opening.

[0063] In one embodiment, the preset regulating loop includes a fifth regulating loop, a sixth regulating loop, a seventh regulating loop and an eighth regulating loop, the fifth preset value of the fifth regulating loop, the sixth preset value of the sixth regulating loop, the seventh preset value of the seventh regulating loop and the eighth preset value of the eighth regulating loop are decreased in magnitude, and the fifth preset value, the sixth preset value, the seventh preset value and the eighth preset value are respectively the target values ​​for the fifth regulating loop, the sixth regulating loop, the seventh regulating loop and the eighth regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network;

[0064] According to the medium pressure value and the low pressure value, determining the target regulating loop between the medium pressure nitrogen pipeline network and the low pressure nitrogen pipeline network in the preset regulating loop includes:

[0065] Determine the relationship between the medium pressure value and the fifth pressure interval preset for the medium pressure nitrogen pipeline network, determine the relationship between the low pressure value and the sixth pressure interval preset for the low pressure nitrogen pipeline network, and determine the target regulation loop; the fifth pressure interval is included in the first pressure interval; the sixth pressure interval is included in the second pressure interval;

[0066] If the medium pressure value is greater than or equal to the maximum value of the fifth pressure interval, and the low pressure value is less than or equal to the minimum value of the sixth pressure interval, the fifth regulation loop is selected as the target regulation loop;

[0067] If the medium pressure value is greater than or equal to the maximum value of the fifth pressure interval, and the low pressure value is greater than or equal to the minimum value of the sixth pressure interval, the sixth regulation loop is selected as the target regulation loop;

[0068] If the medium pressure value is less than or equal to the minimum value of the fifth pressure interval, and the low pressure value is less than or equal to the maximum value of the sixth pressure interval, the seventh regulation loop is selected as the target regulation loop.

[0069] If the medium pressure value is less than or equal to the minimum value of the fifth pressure interval, and the low pressure value is greater than or equal to the maximum value of the sixth pressure interval, the eighth regulation loop is selected as the target regulation loop.

[0070] In one implementation, if the medium pressure value is within the fifth pressure interval and the low pressure value is not lower than the lowest value of the second pressure interval, the medium and low pressure nitrogen connecting valve maintains the current opening.

[0071] In one embodiment, the method further comprises:

[0072] When the low pressure value is greater than or equal to the maximum value of the second pressure interval, the medium and low pressure nitrogen connecting valve is closed.

[0073] In one implementation, when the low-pressure pipeline pressure is greater than or equal to the maximum value of the second pressure interval, the opening of the medium- and low-pressure nitrogen connecting valve can be forced to be 0 without passing through the ramp controller.

[0074] In one embodiment, the method further comprises:

[0075] When the medium pressure value is greater than or equal to the preset relief pressure value, the medium pressure nitrogen pipeline opens the relief valve to perform the relief operation; the preset relief pressure value is greater than the maximum value of the first pressure range.

[0076] The above is a detailed description of an embodiment of the present invention, but the content is only a preferred embodiment of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A method for controlling a medium- and low-pressure nitrogen connecting valve in an oxygen production system, characterized in that: The method comprises: Obtaining a medium pressure value of a medium pressure nitrogen pipeline network and a low pressure value of a low pressure nitrogen pipeline network of an oxygen production system; the normal operating pressures of the medium pressure nitrogen pipeline network and the low pressure nitrogen pipeline network are respectively a first pressure range and a second pressure range; Determining a target regulating loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulating loop according to the medium-pressure pressure value and / or the low-pressure pressure value; Calculating a target opening angle of a medium- and low-pressure nitrogen connecting valve according to the target regulating loop, the medium-pressure value and the low-pressure value; Using a preset switch amplitude value to adjust the medium- and low-pressure nitrogen connecting valve to the target opening angle, so that the pressure of the medium-pressure nitrogen pipeline network is maintained in the first pressure range, and the pressure of the low-pressure nitrogen pipeline network is maintained in the second pressure range; Using a ramp controller to control the opening and closing operations of the medium and low pressure nitrogen connecting valve, the ramp controller receives a preset switching amplitude value and a target opening angle, and uses the preset switching amplitude value to adjust the medium and low pressure nitrogen connecting valve to the target opening angle; When opening the valve, the target valve opening = target opening angle = current opening + n*M; When closing the valve, the target valve opening = target opening angle = current opening - n*M; Among them, n is the number of execution cycles of the controller, and M is the opening and closing amplitude of the medium and low pressure nitrogen connecting valve in each cycle, that is, the current opening of the valve gradually approaches the target opening angle after n execution cycles; The preset regulating loop includes a fifth regulating loop, a sixth regulating loop, a seventh regulating loop and an eighth regulating loop, the fifth preset value of the fifth regulating loop, the sixth preset value of the sixth regulating loop, the seventh preset value of the seventh regulating loop and the eighth preset value of the eighth regulating loop are decreased in order, and the fifth preset value, the sixth preset value, the seventh preset value and the eighth preset value are respectively the target values ​​for the fifth regulating loop, the sixth regulating loop, the seventh regulating loop and the eighth regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network; Determining a target regulation loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulation loop according to the medium-pressure pressure value and the low-pressure pressure value includes: Determine the relationship between the medium pressure value and the fifth pressure interval preset for the medium pressure nitrogen pipeline network, determine the relationship between the low pressure value and the sixth pressure interval preset for the low pressure nitrogen pipeline network, and determine the target regulation loop; the fifth pressure interval is included in the first pressure interval; the sixth pressure interval is included in the second pressure interval; If the medium pressure value is greater than or equal to the maximum value of the fifth pressure interval, and the low pressure value is less than or equal to the minimum value of the sixth pressure interval, then the fifth regulation loop is selected as the target regulation loop; If the medium pressure value is greater than or equal to the maximum value of the fifth pressure interval, and the low pressure value is greater than or equal to the minimum value of the sixth pressure interval, then the sixth regulation loop is selected as the target regulation loop; If the medium pressure value is less than or equal to the minimum value of the fifth pressure interval, and the low pressure value is less than or equal to the maximum value of the sixth pressure interval, then selecting the seventh regulation loop as the target regulation loop; If the medium pressure value is less than or equal to the minimum value of the fifth pressure interval, and the low pressure value is greater than or equal to the maximum value of the sixth pressure interval, the eighth regulation loop is selected as the target regulation loop.

2. The method for controlling the medium and low pressure nitrogen connecting valves of an oxygen production system according to claim 1, characterized in that: The preset regulating loop includes a first regulating loop and a second regulating loop, a first preset value of the first regulating loop is higher than a second preset value of the second regulating loop, and the first preset value and the second preset value are target values ​​for the first regulating loop and the second regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network respectively; Determining a target regulating loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulating loop according to the medium-pressure pressure value includes: Determine the relationship between the medium pressure value and a third pressure range preset for the medium pressure nitrogen pipeline network, and determine a target regulation loop; the third pressure range is included in the first pressure range; If the medium pressure value is greater than or equal to the maximum value of the third pressure interval, selecting the first regulating loop as the target regulating loop; If the medium pressure value is less than or equal to the minimum value of the third pressure interval, the second regulating loop is selected as the target regulating loop.

3. The method for controlling the medium and low pressure nitrogen connecting valves of an oxygen production system according to claim 1, characterized in that: The preset regulating loop includes a third regulating loop and a fourth regulating loop, the third preset value of the third regulating loop is higher than the fourth preset value of the fourth regulating loop, and the third preset value and the fourth preset value are target values ​​for the third regulating loop and the fourth regulating loop to regulate the pressure of the low-pressure nitrogen pipeline network respectively; Determining a target regulation loop between the medium-pressure nitrogen pipeline network and the low-pressure nitrogen pipeline network in a preset regulation loop according to the low-pressure pressure value includes: Determine the relationship between the low pressure value and a fourth pressure interval preset for the low pressure nitrogen pipeline network, and determine a target regulation loop; the fourth pressure interval is included in the second pressure interval; If the low pressure value is greater than or equal to the maximum value of the fourth pressure interval, selecting the fourth regulating loop as the target regulating loop; If the low pressure value is less than or equal to the minimum value of the fourth pressure interval, the third regulating loop is selected as the target regulating loop.

4. The method for controlling the medium and low pressure nitrogen connecting valves of an oxygen production system according to any one of claim 1, characterized in that: The method further comprises: When the low pressure value is greater than or equal to the maximum value of the second pressure range, the medium and low pressure nitrogen connecting valve is closed.

5. The method for controlling the medium and low pressure nitrogen connecting valves of an oxygen production system according to any one of claim 1, characterized in that: The method further comprises: When the medium pressure value is greater than or equal to a preset relief pressure value, the medium pressure nitrogen pipeline opens the relief valve to perform a relief operation; the preset relief pressure value is greater than the maximum value of the first pressure range.

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