Automatic nitrogen charging device and method for low-temperature electrical and signal isolation bin

Abstract

The invention relates to an automatic nitrogen charging device and method for a low-temperature electrical and signal isolation bin, and the device comprises the electrical and signal isolation bin, and a pressure regulator, a needle valve, a one-way valve, a two-position three-way electromagnetic valve and a pressure transmitter are sequentially arranged on a nitrogen header pipe connected with the electrical and signal isolation bin. The two-position three-way electromagnetic valve comprises a first port A, a second port B and a third port C, the first port A and the second port B are respectively connected with a nitrogen header pipe, the third port C of the two-position three-way electromagnetic valve is connected with the emptying pipeline, the two-position two-way electromagnetic valve is arranged on the emptying pipeline, and the pressure transmitter is used for detecting the pressure in the electrical and signal isolation bin. And the control system is in communication connection with the two-position three-way electromagnetic valve, the two-position two-way electromagnetic valve and the pressure transmitter, and controls opening and closing of the two-position three-way electromagnetic valve and the two-position two-way electromagnetic valve according to detected pressure. Automatic nitrogen charging can be achieved, and the situation that a pump system in a low-pressure tank jumps due to excessive nitrogen charging is avoided.

Description

TECHNICAL FIELD

[0001] The application relates to a low-temperature electrical and signal isolation bin automatic nitrogen charging device and method. BACKGROUND

[0002] An LNG cryogenic pump is a relatively key device in a liquefied natural gas (LNG) receiving station, and if the device fails, the receiving station will reduce production or even stop production, so the protection measures for the device must be timely and accurate. In the protection measures for the LNG cryogenic pump, in addition to the electrical protection in the transformer substation, the vibration signal detection of the pump body itself is particularly important.

[0003] Due to the particularity of the working condition of the LNG cryogenic pump, the LNG cryogenic pump needs to be immersed in LNG cryogenic liquid during normal operation, and the power cable and vibration detection signal cable need to be transmitted to the rear-end transformer substation and vibration management system through a special device. Considering the possibility of maintenance and disassembly of the LNG cryogenic pump, the electrical and signal connectors need to be designed to be detachable, which requires the use of an electrical and signal special isolation bin. The isolation bin is in normal operation, one end is in contact with low-temperature natural gas, and the other end is in contact with the atmospheric environment. In order to ensure the normal operation of the isolation bin, dry nitrogen needs to be filled in the isolation bin, and the nitrogen pressure needs to be much higher than the pressure of the low-temperature natural gas. In this way, the possibility of explosive gas entering the isolation bin can be realized, and on the other hand, low-temperature conduction can be avoided, which affects the heat preservation performance of the equipment.

[0004] In a large storage tank in an LNG receiving station, atmospheric storage is usually used, and such a storage tank generally uses a top opening. Therefore, when LNG needs to be exported, the LNG needs to be pressurized and lifted out of the storage tank by a cryogenic pump, and then sent to downstream equipment. The isolation bin is installed on the electrical and vibration signal transmission cable of the cryogenic pump, and a detachable terminal is arranged inside the isolation bin. One end of the isolation bin is connected to the pump well of the cryogenic pump, and the other end is connected to the electrical control cabinet or the vibration transmitter terminal box, which is responsible for transmitting power or transmitting vibration detection signals to the cryogenic pump. It is a key equipment for safe operation of the cryogenic pump, as shown in Figure 3 .

[0005] The isolation bin is a cylindrical structure, and the two ends are connected by flanges. The pressure seal design is adopted to realize the isolation of the internal space of the isolation bin and the atmospheric environment. After the nitrogen gas with pressure is filled in the internal space of the isolation bin, the low-temperature natural gas in the pump well of the cryogenic pump can be isolated from the internal air of the cable duct.

[0006] The current common nitrogen supplement measure is manual nitrogen supplement. The operator needs to go to the site to supplement nitrogen by opening the manual valve. The installation position of the LNG cryogenic pump is generally relatively remote, and the sealing measures of the isolation bin are not easy to achieve stable sealing. Therefore, the pressure loss of the isolation bin occurs from time to time, and it is random and has no fixed rule, which brings unpredictable workload to the operator.

[0007] In actual operation, in order to protect the LNG low-pressure pump, if the seal of the isolation bin fails, causing combustible gas to leak into the isolation bin, it is very likely to cause an explosion accident, so it is necessary to set up the logic of the isolation bin overpressure interlocking LNG low-temperature pump trip. Therefore, during manual nitrogen charging, if the operator is not careful, it is easy to cause the nitrogen charging valve to close too late, causing the isolation bin to be overcharged and overpressure, thereby causing the LNG low-temperature pump to be interlocked and tripped, causing unnecessary trouble. SUMMARY

[0008] In view of the above-mentioned long-standing problems in the art, the inventors have conducted in-depth research and developed a set of automatic nitrogen supplementing device, which realizes automatic nitrogen supplementing without human intervention, reduces the workload of the operator, and also avoids overcharging caused by human error.

[0009] The application is realized by the following technical scheme: A low-temperature electrical and signal isolation bin automatic nitrogen charging device, comprising an electrical and signal isolation bin, a pressure regulator, a needle valve, a check valve, a two-position three-way electromagnetic valve, and a pressure transmitter are sequentially arranged on a nitrogen main pipe connected to the electrical and signal isolation bin, The two-position three-way electromagnetic valve comprises a first port A, a second port B, and a third port C, wherein the first port A and the second port B are respectively connected to the nitrogen main pipe, an emptying pipeline is connected to the third port C of the two-position three-way electromagnetic valve, a two-position two-way electromagnetic valve is arranged on the emptying pipeline, the pressure transmitter is arranged on a nitrogen supplementing pipeline between the two-position three-way electromagnetic valve and the electrical and signal isolation bin, and is used for detecting the pressure in the electrical and signal isolation bin; a control system is in communication connection with the two-position three-way electromagnetic valve, the two-position two-way electromagnetic valve, and the pressure transmitter, and controls the opening and closing of the two-position three-way electromagnetic valve and the two-position two-way electromagnetic valve according to the detected pressure.

[0010] Further, the electrical and signal isolation bin is provided with an air inlet and an air outlet. The air inlet is connected to the nitrogen supplementing pipeline, and can supplement nitrogen to the isolation bin; the air outlet is sealed by a plugging flange (or a plug), to reduce nitrogen leakage.

[0011] Further, when the pressure detected by the pressure transmitter is lower than the set value (generally 0.5±0.1 MPa, preferably 0.5 MPa), the two-position three-way electromagnetic valve is opened by the control system, the A and B ports are conducted, the B and C ports are closed, the A port and the B port are communicated, and then the nitrogen source is communicated with the isolation bin, to supplement the pressure of the electrical and signal isolation bin.

[0012] Further, when the pressure detected by the pressure transmitter is higher than the required value of the isolation chamber (generally 0.8±0.1MPa, preferably 0.8MPa), the two-position three-way electromagnetic valve is closed by the output signal of the control system, the A and B ports are closed, the B and C ports are turned on, the isolation chamber is communicated with the exhaust port, and the air supplement is stopped.

[0013] Further, when the pressure detected by the pressure transmitter is higher than the maximum pressure allowed by the isolation chamber (generally 1.0±0.1MPa, preferably 1.0MPa), the two-position three-way electromagnetic valve is closed by the output signal of the control system, the A and B ports are closed, the B and C ports are turned on, the isolation chamber is communicated with the exhaust port, and the two-position two-way electromagnetic valve is opened to discharge the overpressure gas from the isolation chamber, thereby avoiding the influence of system overpressure on the safety of the isolation chamber.

[0014] Further, in the case of active diffusion of the isolation chamber (when the discharge electromagnetic valve (two-position two-way electromagnetic valve) is opened), the control system sends an alarm signal to prompt the operator to pay attention and timely on-site troubleshooting to detect whether the electrical and signal isolation chamber leaks gas, if so, the low-temperature pump needs to be stopped urgently, and the isolation chamber that leaks gas needs to be replaced in time.

[0015] In the present application, the electrical and signal isolation chamber includes an electrical isolation chamber and a signal isolation chamber.

[0016] The present application further provides an automatic nitrogen charging method for the low-temperature electrical and signal isolation chamber using the above device, which comprises: In the process, dry normal-temperature nitrogen is introduced into the nitrogen main pipe, reduced to a safe pressure (generally 0.6~0.8MPaG) by a self-operated pressure regulator, then passed through a needle valve, and the opening of the needle valve is adjusted to regulate the nitrogen flow charged into the isolation chamber, so that the time for charging nitrogen into the isolation chamber from zero to full is controlled within 6~12 minutes, preferably 8~10 minutes, to avoid the impact on the equipment caused by rapid charging of nitrogen and the triggering of the safety interlock action of the low-temperature pump caused by the pressure fluctuation due to rapid charging of nitrogen, and then a check valve is connected to ensure that nitrogen can only flow from the nitrogen main pipe to the electrical and signal isolation chamber. After the nitrogen comes out of the check valve, it enters the two-position three-way electromagnetic valve, the pressure transmitter and the low-temperature electrical and signal isolation chamber in turn, and the pressure transmitter detects the nitrogen pressure in the low-temperature electrical and signal isolation chamber.

[0017] When the pressure detected by the pressure transmitter is lower than the set value (generally 0.5±0.1MPa, preferably 0.5MPa), the two-position three-way electromagnetic valve is opened by the output signal of the control system, the A and B ports are turned on, the B and C ports are closed, the nitrogen source is communicated with the isolation chamber, and the pressure of the electrical and signal isolation chamber is supplemented.

[0018] When the pressure detected by the pressure transmitter is higher than the required value of the isolation bin (generally 0.8±0.1MPa, preferably 0.8MPa), the two-position three-way electromagnetic valve is closed by the output signal of the control system, the A and B ports are closed, the B and C ports are conducted, the isolation bin is communicated with the exhaust port, and the air supplement is stopped.

[0019] When the pressure detected by the pressure transmitter is higher than the maximum pressure allowed by the isolation bin (generally 1.0±0.1MPa, preferably 1.0MPa), the two-position three-way electromagnetic valve is closed by the output signal of the control system (the A and B ports are closed, and the B and C ports are conducted), and the two-position two-way electromagnetic valve is opened at the same time, so that the overpressure gas is discharged from the isolation bin, and the safety of the isolation bin is avoided from being affected by the overpressure of the system.

[0020] When gas leakage occurs in the isolation bin or nitrogen charging is excessive, in order to avoid danger due to overpressure of the system, the overpressure medium in the isolation bin needs to be actively diffused, and when the isolation bin is actively diffused (the discharge electromagnetic valve is opened), the control system sends an alarm signal to prompt the operator to pay attention and timely on-site troubleshooting to detect whether gas leakage occurs in the isolation bin, if so, the low-temperature pump needs to be stopped urgently, and the isolation bin where gas leakage occurs needs to be replaced. The two-position three-way electromagnetic valve can be randomly switched between the two states of isolation bin charging and discharging, but it is not possible to realize the discharge of the isolation bin by only actuating the two-position three-way electromagnetic valve, and the discharge can only be realized by actuating the two-position two-way electromagnetic valve, which improves the system reliability and avoids the automatic discharge of the system due to the failure of a single electromagnetic valve, thereby affecting the safe operation of the isolation bin. The two-position two-way electromagnetic valve is adopted in the scheme, which can ensure that the system discharge does not occur when only the two-position three-way electromagnetic valve is actuated, and the discharge can only be realized by the cooperation of the two-position two-way electromagnetic valve. The two-position three-way electromagnetic valve and the two-position two-way electromagnetic valve are connected in series, so that the availability and safety of the entire nitrogen supply system of the isolation bin are improved, and the safety of the entire system is ensured.

[0021] Through the setting of the device, the workload of the operator can be reduced, the automatic nitrogen charging control process of the electrical and signal isolation bin can be realized, the low-temperature pump trip caused by overcharging of the isolation bin pressure can be avoided, the overpressure of the isolation bin can be emptied in time, the overpressure diffusion function of the LNG low-temperature pump isolation bin is realized, and an alarm signal is generated to prompt the operator to pay attention and timely eliminate the fault, thereby avoiding the safety of the isolation bin affected by the overpressure of the system.

[0022] In the present application, the nitrogen source of the nitrogen main pipe is generally liquid nitrogen or an air compression nitrogen device. Advantages of the present application

[0023] (1) The pressure change is detected in real time online by the control system, and the system automatically judges whether the isolation bin needs to be supplemented, thereby reducing the workload of the operator; (2) Through the real-time detection of the isolation chamber pressure by the control system, the overpressure situation of the isolation chamber leakage is found in time, and the active discharge measures are adopted, thereby improving the safety of the system; (3) Avoiding the system trip caused by excessive nitrogen filling; (4) Through the starting of the discharge valve, the health condition of the isolation chamber is known in time, and the equipment is prevented from running with disease, thereby avoiding serious accidents.

[0024] In summary, the automatic gas supplementing device has the advantages of realizing automatic control, reducing the workload of the operating personnel, reducing the interlocking trip caused by human errors, improving the safety of the equipment operation through automatic detection and control, saving energy and reducing consumption, and controlling the process safely and stably. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 It is a schematic diagram of the prior art nitrogen supplementing device for the electrical and signal isolation chamber.

[0026] Figure 2 It is a schematic diagram of the automatic nitrogen filling device for the low-temperature electrical and signal isolation chamber.

[0027] Figure 3 It is a schematic diagram of the low-temperature storage tank.

[0028] BRIEF DESCRIPTION OF DRAWINGS L1: nitrogen main pipe; 1: pressure regulator; V1: one-way valve; V2: No. 1 on-off valve; P1: pressure transmitter; 2: control system; 3: electrical and signal isolation chamber; V3: No. 2 on-off valve; V4: needle valve; V5: two-position three-way electromagnetic valve; V6: two-position two-way electromagnetic valve; 4: plugging flange; 10: low-temperature storage tank; 11: low-temperature pump in the tank; 12: tank wall; 13: low-temperature pump barrel; 14: low-temperature pump hanger cable; 15: tank hanger roof; 16: power cable; 17: vibration signal cable; 31: electrical isolation chamber; 32: signal isolation chamber; 40: electric control cabinet; 50: vibration signal junction box. DETAILED DESCRIPTION

[0029] The application will be further described below by means of specific embodiments in combination with the drawings.

[0030] Figure 3This is a schematic diagram of a cryogenic storage tank. A cryogenic pump barrel 13 is installed inside the cryogenic storage tank 10, extending to near the bottom of the tank. The cryogenic pump 11 is lowered to the bottom of the cryogenic pump barrel 13 via a cryogenic pump hoisting cable 14. The power cable 16 of the cryogenic pump connects to an electrical isolation chamber 31 and an electrical control cabinet 40. A vibration signal cable 17 connects to a signal isolation chamber 32 and a vibration signal junction box 50. Both the electrical isolation chamber 31 and the signal isolation chamber 32 are connected to a dry nitrogen source. One end of the electrical isolation chamber and the signal isolation chamber is connected to the cryogenic pump well, and the other end is connected to the electrical control cabinet or vibration transmitter junction box. They are responsible for transmitting kinetic energy or vibration detection signals to the cryogenic pump and are key equipment for the safe operation of the cryogenic pump. The isolation chamber has a cylindrical structure and adopts a pressure-bearing and sealed design to isolate the internal space of the isolation chamber from the atmospheric environment. After being filled with pressurized nitrogen, the cryogenic natural gas from the cryogenic pump well is isolated from the air inside the cable conduit. The sealing measures of the isolation chamber are not easy to achieve a stable seal, so depressurization of the isolation chamber occurs frequently, requiring operators to manually replenish nitrogen by opening valves on-site. In actual operation, to protect the LNG low-pressure pump, if the isolation chamber seal fails and flammable gas leaks into the isolation chamber, it could potentially cause an explosion. Therefore, an overpressure interlock logic for tripping the LNG cryogenic pump is required. Thus, during manual nitrogen filling, slight operator inattention can easily lead to the nitrogen filling valve not closing in time, resulting in excessive nitrogen filling and overpressure in the isolation chamber, causing the LNG cryogenic pump to trip and resulting in unnecessary trouble.

[0031] like Figure 2 As shown, this application discloses an automatic nitrogen filling device for a cryogenic electrical and signal isolation chamber, which includes an electrical and signal isolation chamber 3. A pressure regulator 1, a needle valve V4, a check valve V1, a two-position three-way solenoid valve V5, and a pressure transmitter P1 (the pressure transmitter P1 is located on the side closer to the electrical and signal isolation chamber 3) are sequentially arranged on the nitrogen main pipe L1 connected to the electrical and signal isolation chamber.

[0032] The two-position three-way solenoid valve V5 includes a first port A, a second port B, and a third port C. The first port A and the second port B are respectively connected to the nitrogen main pipe. The third port C of the two-position three-way solenoid valve is connected to the vent pipe L2. The two-position two-way solenoid valve V6 is installed on the vent pipe L2. The pressure transmitter P1 is installed on the nitrogen replenishment line between the two-position three-way solenoid valve V5 and the electrical and signal isolation chamber 3. It is used to detect the pressure in the electrical and signal isolation chamber 3. The control system 2 is communicatively connected to the two-position three-way solenoid valve V5, the two-position two-way solenoid valve V6, and the pressure transmitter P1. The control system 2 controls the opening and closing of the two-position three-way solenoid valve and the two-position two-way solenoid valve according to the pressure detected by the pressure transmitter P1.

[0033] The electrical and signal isolation chamber is provided with an air inlet and an air outlet. The air inlet is connected with a nitrogen supplement pipeline, and nitrogen can be supplemented to the isolation chamber. The air outlet is sealed by a sealing flange 4 (or a plug), so as to reduce nitrogen leakage.

[0034] When the pressure detected by the pressure transmitter is lower than the set value (generally 0.5±0.1 MPa, preferably 0.5 MPa), the two-position three-way electromagnetic valve is opened by the output signal of the control system, the A and B ports are connected, the B and C ports are closed, the A and B ports are connected, the nitrogen source is connected with the isolation chamber, and the electrical and signal isolation chamber is pressurized.

[0035] When the pressure detected by the pressure transmitter is higher than the required value of the isolation chamber (generally 0.8±0.1 MPa, preferably 0.8 MPa), the two-position three-way electromagnetic valve is closed by the output signal of the control system, the A and B ports are closed, the B and C ports are connected, the isolation chamber is connected with the exhaust electromagnetic valve V6, and the air supplement is stopped (the air outlet of the isolation chamber is sealed and abandoned, and the electromagnetic valve V6 is connected with the air inlet of the isolation chamber to realize the exhaust function of the isolation chamber controlled by the electromagnetic valve V6, and the air inlet of the isolation chamber simultaneously functions as the air outlet).

[0036] When the pressure detected by the pressure transmitter is higher than the maximum pressure allowed by the isolation chamber (generally 1.0±0.1 MPa, preferably 1.0 MPa), the two-position three-way electromagnetic valve is closed by the output signal of the control system, the A and B ports are closed, the B and C ports are connected, the isolation chamber is connected with the exhaust electromagnetic valve V6, and the two-position two-way electromagnetic valve V6 is opened to exhaust the overpressure gas from the isolation chamber, so as to avoid the influence of system overpressure on the safety of the isolation chamber.

[0037] In the case of active diffusion of the isolation chamber (when the exhaust electromagnetic valve (two-position two-way electromagnetic valve) is opened), the control system sends an alarm signal to prompt the operator to pay attention and timely on-site investigation to detect whether the electrical and signal isolation chamber leaks gas. If so, the low-temperature pump needs to be stopped immediately, and the isolation chamber that leaks gas needs to be replaced in time. Example 1

[0038] In this process, dry nitrogen is introduced into the nitrogen main pipeline, and is reduced to a safe pressure (generally 0.6-0.8 MPaA) by a self-operated pressure regulator 1. Then, the nitrogen is passed through a needle valve V4, and the opening of the needle valve can be adjusted to regulate the flow of nitrogen charged into the isolation chamber, so as to control the time from zero to full filling of the isolation chamber within 8-10 minutes, avoid the impact of rapid filling of nitrogen on the equipment, and also avoid the pressure fluctuation caused by rapid filling of nitrogen to trigger the safety interlock action of the low-temperature pump. A check valve V1 is connected, which ensures that the nitrogen can only flow from the nitrogen main pipeline to the electrical and signal isolation chamber. A two-position three-way electromagnetic valve V5 and a pressure transmitter P1 are sequentially arranged on the pipeline after the check valve V1, and finally connected to the inlet of the electrical and signal isolation chamber 3.

[0039] Two three-way electromagnetic valve V5 includes first port A, second port B and third port C, wherein the first port A and the second port B are connected with nitrogen main pipe respectively, the third port C of the two three-way electromagnetic valve is connected with exhaust pipeline L2, two two-way electromagnetic valve V6 is arranged on the exhaust pipeline L2, pressure transmitter P1 is arranged on the nitrogen supplement pipeline between the two three-way electromagnetic valve V5 and the electrical and signal isolation bin 3, which is used for detecting the pressure in the electrical and signal isolation bin 3, the control system 2 is in communication connection with the two three-way electromagnetic valve V5, the two two-way electromagnetic valve V6 and the pressure transmitter P1, and the opening and closing of the two three-way electromagnetic valve and the two two-way electromagnetic valve are controlled according to the pressure detected by the pressure transmitter P1.

[0040] 1. When the pressure detected by the pressure transmitter is lower than the set value (0.5 MPa), the two three-way electromagnetic valve is opened by the signal output by the control system, the A and B ports are conducted, the B and C ports are closed, the A port and the B port are communicated, then the nitrogen source is communicated with the isolation bin, and the electrical and signal isolation bin is pressure compensated; 2. When the pressure detected by the pressure transmitter is higher than the required value (0.8 MPa) of the isolation bin, the two three-way electromagnetic valve is closed by the signal output by the control system, the A and B ports are closed, the B and C ports are conducted, then the isolation bin is communicated with the exhaust port, and the air supply is stopped; 3. When the pressure detected by the pressure transmitter is higher than the maximum pressure (1.0 MPa) allowed by the isolation bin, the two three-way electromagnetic valve is closed by the signal output by the control system, the A and B ports are closed, the B and C ports are conducted, and the two two-way electromagnetic valve is opened, so that the overpressure gas is discharged from the isolation bin, and the safety of the isolation bin is avoided due to overpressure of the system; 4. When the gas leakage occurs in the isolation bin or the nitrogen charging is excessive, in order to avoid the danger of the system due to overpressure, the overpressure medium in the isolation bin needs to be actively diffused, under the condition of active diffusion of the isolation bin, the control system sends an alarm signal (when the discharge electromagnetic valve is opened), prompting the operator to pay attention, and timely taking measures to carry out on-site investigation, detecting whether the gas leakage occurs in the isolation bin, if so, the low temperature pump needs to be stopped urgently, and the isolation bin with gas leakage needs to be replaced in time.

[0041] The embodiment 1 realizes automatic control, reduces the workload of the operator, reduces the interlocking trip caused by human error, improves the safety of the equipment operation through automatic detection and control, saves energy and reduces consumption, and controls the process safely and stably. Comparative example 1

[0042] Use Figure 1The common isolation warehouse supplementary nitrogen device, nitrogen main pipe sets pressure regulator 1, check valve V1, 1# switch valve V2, pressure transmitter P1 in turn, finally connects to the import of electrical and signal isolation warehouse 3, pressure transmitter P1 connects control system 2, and opens 1# switch valve V2 to give isolation warehouse supplementary nitrogen, at this time, two kinds of working conditions are divided.Two kinds of working conditions are that 1# switch valve V2 is fully opened, and 2# switch valve V3 is left with a small opening degree (always has nitrogen flow), to ensure that the nitrogen pressure in the isolation warehouse is stable, and the working state of the isolation warehouse is monitored by real-time monitoring of the pressure of pressure transmitter P1;Another kind of working condition is that 1# switch valve V2 is fully closed, and 2# switch valve V3 is also fully closed, and the operator inspects periodically according to the cycle, checks the nitrogen pressure in the isolation warehouse, and manually opens 1# switch valve V2 to supplement air when the pressure is low, which needs to be particularly careful, and a little bit of attention to overcharge, which is easy to cause the low-temperature pump interlock to stop.

[0043] Obviously, the above embodiments are only examples for clearly illustrating, but not limitation of the embodiments. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and cannot be exhausted. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. An automatic nitrogen filling device for a cryogenic electrical and signal isolation chamber, characterized in that, It includes electrical and signal isolation chambers. A pressure regulator, needle valve, check valve, two-position three-way solenoid valve, and pressure transmitter are sequentially installed on the nitrogen main pipe connecting the electrical and signal isolation chambers. The two-position three-way solenoid valve includes a first port A, a second port B, and a third port C. The first port A and the second port B are respectively connected to the nitrogen main pipe. The third port C of the two-position three-way solenoid valve is connected to an vent pipe. A two-position two-way solenoid valve is installed on the vent pipe. A pressure transmitter is installed on the nitrogen replenishment line between the two-position three-way solenoid valve and the electrical and signal isolation chamber. It is used to detect the pressure in the electrical and signal isolation chamber. The control system is connected to the two-position three-way solenoid valve, the two-position two-way solenoid valve, and the pressure transmitter. It controls the opening and closing of the two-position three-way solenoid valve and the two-position two-way solenoid valve according to the detected pressure.

2. The automatic nitrogen filling device for the cryogenic electrical and signal isolation chamber according to claim 1, characterized in that, The electrical and signal isolation chamber is equipped with an air inlet and an exhaust outlet. The air inlet is connected to a nitrogen replenishment pipeline to replenish the isolation chamber with nitrogen. The exhaust outlet is sealed with a sealing flange or a plug.

3. The automatic nitrogen filling device for the cryogenic electrical and signal isolation chamber according to claim 1 or 2, characterized in that, Electrical and signal isolation chambers include electrical isolation chambers and signal isolation chambers.

4. The automatic nitrogen filling device for the cryogenic electrical and signal isolation chamber according to any one of claims 1-3, characterized in that, When the pressure transmitter detects a pressure lower than the set value (e.g., 0.5 ± 0.1 MPa, preferably 0.5 MPa), the control system outputs a signal to open the two-position three-way solenoid valve. Ports A and B are open, while ports B and C are closed. When ports A and B are connected, the nitrogen source is connected to the isolation chamber, thus pressurizing the electrical and signal isolation chambers.

5. The automatic nitrogen filling device for the cryogenic electrical and signal isolation chamber according to any one of claims 1-4, characterized in that, When the pressure detected by the pressure transmitter is higher than the required value of the isolation chamber (e.g., 0.8±0.1MPa, preferably 0.8MPa), the control system outputs a signal to close the two-position three-way solenoid valve, closing ports A and B, and opening ports B and C, connecting the isolation chamber to the exhaust port and stopping the gas supply.

6. The automatic nitrogen filling device for the cryogenic electrical and signal isolation chamber according to any one of claims 1-5, characterized in that, When the pressure detected by the pressure transmitter is higher than the maximum allowable pressure of the isolation chamber (e.g., 1.0 ± 0.1 MPa, preferably 1.0 MPa), the control system outputs a signal to close the two-position three-way solenoid valve, closing ports A and B and opening ports B and C, connecting the isolation chamber to the exhaust port. At the same time, the two-position two-way solenoid valve is opened to discharge the overpressure gas from the isolation chamber, preventing the system overpressure from affecting the safety of the isolation chamber.

7. The automatic nitrogen filling device for the cryogenic electrical and signal isolation chamber according to any one of claims 1-6, characterized in that, When the solenoid valve of the isolation chamber is opened under active venting, the control system issues an alarm signal to alert the operator and prompt them to conduct an on-site inspection to check for gas leaks in the electrical and signal isolation chambers. If a gas leak is detected, the cryogenic pump must be stopped immediately and the isolation chamber with the gas leak must be replaced promptly.

8. A method for automatically filling a cryogenic electrical and signal isolation chamber with nitrogen using the automatic nitrogen filling device for cryogenic electrical and signal isolation chambers according to any one of claims 1-7, the method comprising: Dry, room-temperature nitrogen is introduced into the nitrogen main pipe and reduced to a safe pressure via a self-regulating pressure regulator. Then, it passes through a needle valve. By adjusting the opening of the needle valve, the flow rate of nitrogen into the isolation chamber is regulated, ensuring that the time for the isolation chamber to fill from zero to full is controlled within 6-12 minutes, preferably within 8-10 minutes. This avoids the impact of rapid nitrogen filling on the equipment and prevents pressure fluctuations that could trigger the cryogenic pump's safety interlock. A check valve is then connected to ensure that nitrogen flows only from the nitrogen main pipe to the electrical and signal isolation chamber. After exiting the check valve, the nitrogen sequentially enters a two-position three-way solenoid valve, a pressure transmitter, and the cryogenic electrical and signal isolation chamber. The pressure transmitter monitors the nitrogen pressure within the cryogenic electrical and signal isolation chamber. When the pressure transmitter detects that the pressure is lower than the pressure set value, the control system outputs a signal to open the two-position three-way solenoid valve. Ports A and B are open, while ports B and C are closed. The nitrogen source is connected to the isolation chamber to replenish the pressure of the electrical and signal isolation chambers. When the pressure detected by the pressure transmitter is higher than the required value of the isolation chamber, the control system outputs a signal to close the two-position three-way solenoid valve. Ports A and B are closed, while ports B and C are open, connecting the isolation chamber to the exhaust port and stopping the gas supply. When the pressure detected by the pressure transmitter is higher than the maximum allowable pressure of the isolation chamber, the control system outputs a signal to close the two-position three-way solenoid valve, with ports A and B closed and ports B and C open. At the same time, the two-position two-way solenoid valve is opened to discharge the overpressure gas from the isolation chamber, so as to avoid the system overpressure affecting the safety of the isolation chamber. When the solenoid valve of the discharge chamber is opened during active venting of the isolation chamber, the control system issues an alarm signal to alert the operator and prompt them to conduct an on-site inspection to check for gas leaks in the isolation chamber. If a gas leak is detected, the cryogenic pump must be stopped immediately and the isolation chamber with the gas leak must be replaced promptly.

9. The automatic nitrogen filling method for a cryogenic electrical and signal isolation chamber according to claim 8, characterized in that, The nitrogen source for the nitrogen main is either liquid nitrogen vaporization or compressed nitrogen from an air compressor.

10. The automatic nitrogen filling method for a cryogenic electrical and signal isolation chamber according to claim 8, characterized in that, The safe pressure is 0.6~0.8 MPaG; and / or The pressure setpoint is 0.5 ± 0.1 MPa, preferably 0.5 MPa; and / or The required pressure for the isolation chamber is 0.8 ± 0.1 MPa, preferably 0.8 MPa; and / or The maximum allowable pressure of the isolation chamber is 1.0 ± 0.1 MPa, preferably 1.0 MPa.

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