Displacement testing device and method for pressure relief valve

Abstract

The invention relates to the technical field of pressure relief valves, in particular to a pressure relief valve displacement testing device and method.The pressure relief valve displacement testing device comprises a gas source and a testing tank, the gas source is suitable for providing testing pressure, a pressure reducing valve and an electromagnetic valve are arranged between the gas source and the testing tank, and the testing tank is suitable for installing a to-be-tested pressure relief valve; compared with the prior art, by means of the double-test design of'pressure relief valve test + sealing cover comparison test ', two key error sources are accurately counteracted: 1, extra air inflow interference caused by switch delay of the air inlet electromagnetic valve, 2, pressure relief valve test, 3, pressure relief valve test, 4, pressure relief valve test, 5, pressure relief valve test, 6, pressure relief valve test and 7, pressure relief valve test are combined, and the test tank is provided with a pressure sensor for monitoring pressure. And secondly, the system recognizes the redundant air inlet influence within the time difference of the valve opening pressure. Meanwhile, a high-frequency pressure sensor and a timer are adopted to collect data in real time, volume conversion in a standard state is completed in combination with an ideal gas state equation, interference of test environment temperature and pressure fluctuation on results is avoided, and accuracy of displacement calculation results is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of pressure relief valves, and particularly to a pressure relief valve displacement test device and method. Background Art

[0002] A pressure relief valve is a pressure protection device for oil-immersed power transformers. The "displacement" of a pressure relief valve refers to the volume / mass of the medium (such as transformer oil, gas) that can be released per unit time, which is a key parameter calculated based on the device volume and potential gas production during design (for example, the valve supporting an 110 kV transformer needs to meet an oil discharge capacity of ≥50 m³ / h).

[0003] A pressure relief valve displacement test device tests the oil / gas discharge capacity of a valve under rated pressure by simulating the gas production scenario inside a transformer, measures the actual displacement of the valve under the rated opening pressure, and determines whether it reaches the design value.

[0004] The pressure relief valve displacement performance test installs the pressure relief valve on a dedicated test device. Under normal temperature and 115 °C conditions, a flowmeter is used to measure the actual displacement of the liquid when the pressure relief valve opens at different pressurization speeds.

[0005] Traditional test methods have significant efficiency bottlenecks in mass production scenarios:

[0006] Firstly, the air source preparation process takes a long time, and during the pressure relief stage, it is necessary to wait for a long time for the system pressure to stabilize before valid data can be collected, directly resulting in an extended test cycle for a single valve. When mass-producing, the overall production and test duration increase significantly, seriously affecting the release of production capacity.

[0007] Secondly, there are obvious lags and accuracy deviations in the opening point judgment. During the test, when the valve is inflated until it opens automatically, the traditional method relies on the pressure peak to determine the opening moment. However, the valve opening is a dynamic and progressive process: in the initial stage, the valve core only opens a tiny gap and medium leakage already occurs. At this time, the system pressure has started to drop but has not reached the theoretical peak, and the actual pressure relief state has already entered. The judgment logic based on the peak cannot capture this early opening signal, easily misjudging subsequent pressure fluctuations as the opening point, or delaying the judgment due to the absence of the peak, resulting in a distorted recognition of the opening moment. Summary of the Invention

[0008] In view of this, the present invention provides a pressure relief valve displacement test device and method, which can not only perform displacement tests on pressure relief valves efficiently and quickly, but also have better accuracy than traditional methods and eliminate delay errors.

[0009] To solve the above-mentioned technical problems, the present invention provides a pressure relief valve displacement testing device, comprising a gas source and a test tank. The gas source is suitable for providing test pressure. A pressure reducing valve and a solenoid valve are provided between the gas source and the test tank. The outlet pressure range of the pressure reducing valve is 400-500 kPa. The test tank is suitable for installing the pressure relief valve to be tested. The test tank is also equipped with a pressure sensor for monitoring pressure and a temperature sensor for monitoring temperature.

[0010] Furthermore, the air source includes an air compressor and an air storage tank connected to the output end of the air compressor.

[0011] Furthermore, the volume of the gas storage tank is not less than 150L, ​​and the gas storage pressure range is 700-800kPa.

[0012] Furthermore, the pressure sensor is a high-frequency dynamic pressure sensor with a response frequency of not less than 20kHz and a range of 0 to 300kPa.

[0013] Another aspect of the present invention provides a method for testing the discharge capacity of a pressure relief valve, the method comprising:

[0014] Clamp the pressure relief valve to be tested onto the test tank, ensuring a tight seal between the pressure relief valve and the test tank.

[0015] Turn on the air intake and pressure regulation, turn on the air compressor to supply air into the air tank, and adjust the pressure reducing valve at the outlet of the air tank to make the pressure inside the test tank rise steadily.

[0016] Real-time monitoring and recording, and real-time calculation of the pressure change rate inside the test tank;

[0017] Determine the opening pressure and record the time. When the pressure inside the test tank changes significantly, the pressure corresponding to that node is set as the opening pressure P0 of the pressure relief valve, and the time t1 from the actual opening of the pressure relief valve to the system determining that it is open is recorded.

[0018] After the intake and stability monitoring are turned off, the solenoid valve is turned off when the system determines that the pressure relief valve is open, until the pressure and temperature in the test tank are stable. At this time, the pressure P1 and temperature T1 in the test tank are recorded.

[0019] Remove the pressure relief valve and seal the test container. Repeat the above steps until the pressure inside the test container reaches P0. Continue to supply air and maintain this pressure for time t1. Close the solenoid valve until the pressure and temperature inside the test container stabilize. At this point, record the pressure P inside the test container. ２ and temperature T ２ ;

[0020] Calculate the gas volumes V1 and V in the test tank. ２Based on the perfect gas law PV=nRT, calculate the volume V of the gas in the test tank at standard atmospheric pressure and a temperature of 20℃. １ and V ２， The displacement of the pressure relief valve under test is obtained by calculating the difference between V2 and V1.

[0021] Furthermore, during the inlet opening and pressure regulation steps, the pressure inside the test tank steadily increases at a rate of 25–40 kPa / s.

[0022] Furthermore, in the real-time monitoring and recording step, the pressure sensor collects pressure change data inside the test tank in real time, the timer records the corresponding time synchronously, and the pressure change rate inside the test tank is calculated in real time based on the pressure and time data.

[0023] Furthermore, in the steps of determining the opening pressure and recording time, when the pressure relief valve reaches the opening pressure, the pressure relief valve opens and releases gas, at which point the pressure inside the test tank changes significantly.

[0024] The beneficial effects of the above-described technical solution of the present invention are as follows:

[0025] 1. Compared with existing technologies, this invention, through a dual-test design of "pressure relief valve test + sealing cap comparison test," accurately offsets two key error sources: first, the additional air intake interference caused by the delay in the opening and closing of the intake solenoid valve; and second, the redundant air intake effect within the time difference in the system's identification of the valve opening pressure. Simultaneously, it employs a high-frequency pressure sensor and timer to collect data in real time, and combines this with the ideal gas law to complete the volume conversion under standard conditions, avoiding the interference of temperature and pressure fluctuations in the test environment on the results and ensuring the accuracy of the displacement calculation results.

[0026] 2. This invention calculates the pressure change rate inside the test tank in real time. Based on the point of sudden drop in the rate of change, the exhaust behavior will immediately change the pressure change pattern inside the test tank. Regardless of the displacement, the rate of change will show a significant sudden change. This sudden change point is almost synchronous with the actual start of exhaust by the valve. The lag is only the sampling interval of the high-frequency sensor, which is usually on the order of milliseconds. This "effect correlation judgment" can accurately lock the critical moment when the valve goes from "closed" to "open for exhaust", ensuring that the recording error of the opening time T1 is minimized. This provides an accurate time reference for subsequent displacement calculation and avoids the deviation in intake volume calculation caused by the lag in the judgment of the moment. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0028] Figure 2 This is one of the schematic diagrams illustrating the pressure and time changes in the test tank during the opening process of the pressure relief valve, according to one embodiment of the present invention.

[0029] Figure 3 This is a second schematic diagram illustrating the pressure and time changes in the test tank during the opening process of the pressure relief valve, according to one embodiment of the present invention.

[0030] Figure 4 This is the third schematic diagram of the pressure change of the test tank over time during the opening process of the pressure relief valve in one embodiment of the present invention.

[0031] In the diagram: 1. Air compressor; 2. Air tank; 3. Pressure reducing valve; 4. Solenoid valve; 5. Test tank; 6. Pressure sensor; 7. Temperature sensor. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will be described in conjunction with the accompanying drawings of the embodiments of the present invention. Figure 1-4 The technical solutions of the embodiments of the present invention will be clearly and completely described herein. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0033] like Figure 1 As shown: A pressure relief valve displacement testing device includes an air source and a test tank 5. The air source includes an air compressor 1 and an air storage tank 2 connected to the output end of the air compressor 1. The air source is suitable for providing test pressure. A pressure reducing valve 3 and a solenoid valve 4 are provided between the air storage tank 2 and the test tank 5. The outlet pressure range of the pressure reducing valve 3 is 400-500 kPa. The pressure reducing valve 3 can adjust to provide a stable test air source. The test tank 5 is suitable for installing the pressure relief valve to be tested. The test tank 5 is also equipped with a pressure sensor 6 and a temperature sensor 7 for monitoring pressure.

[0034] In the above embodiments,

[0035] The volume of the gas storage tank 2 is not less than 150L, ​​and the gas storage pressure range is 700~800kPa;

[0036] The volume of gas storage tank 2 is greater than the volume of test tank 5;

[0037] Pressure sensor 6 is a high-frequency dynamic pressure sensor with a response frequency of not less than 20kHz and a range of 0 to 300kPa.

[0038] Air compressor 1 has a rated pressure of 800 kPa;

[0039] Solenoid valve 4 control response frequency: 20kHz.

[0040] Specifically, a method for testing the discharge capacity of a pressure relief valve includes:

[0041] Experimental preparation:

[0042] Equipment configuration: Prepare an air compressor 1 with a rated pressure of 800 kPa to provide air source for the test; prepare an air storage tank 2 with a volume of 300 L, the outlet of which needs to be equipped with a pressure reducing valve 3. The outlet pressure of the pressure reducing valve 3 can be adjusted within the range of 400 kPa-500 kPa to achieve a stable rate of test air source output; prepare a test tank 5 with a volume of 250 L (i.e. 0.25 m³) as the pressure and gas container for the test; a high-frequency pressure sensor 6 for real-time pressure monitoring; a timer for recording time; and an intake solenoid valve 4 for controlling the intake on / off.

[0043] Equipment inspection: It was confirmed that the air compressor 1, air tank 2, pressure reducing valve 3, test tank 5, high frequency pressure sensor 6, timer, and intake solenoid valve 4 were all in normal working condition. The adjustment function of pressure reducing valve 3 was normal. The accuracy of high frequency pressure sensor 6 and timer met the test requirements. All equipment connections were well sealed and there was no air leakage.

[0044] First trial:

[0045] Clamp the pressure relief valve: Accurately clamp the pressure relief valve to be tested onto the test tank 5, ensuring a tight seal between the pressure relief valve and the calibration bench and test tank 5 to prevent air leakage during the test.

[0046] Intake and pressure regulation: Start the system and the intake solenoid valve 4 will be opened automatically. By adjusting the pressure reducing valve 3 at the outlet of the air storage tank 2, the pressure in the test tank 5 will rise steadily at a rate of 30 kPa / s.

[0047] Real-time monitoring and recording: The system uses a high-frequency pressure sensor 6 to collect pressure change data in the test tank 5 in real time, and uses a timer to record the corresponding time synchronously. The system calculates the pressure change rate in real time based on the collected pressure and time data.

[0048] Determine the opening pressure and record the time: When the pressure inside test tank 5 reaches the opening pressure of the pressure relief valve, the pressure relief valve begins to open and release air. At this time, the original pressure change rate inside test tank 5 will change significantly.

[0049] like Figure 2-4 As shown: Depending on the discharge capacity of the pressure relief valve, there are three possible rates of pressure change within test tank 5:

[0050] When the displacement is less than the intake volume, the pressure still rises, resulting in a sudden drop in the rate of rise.

[0051] With displacement and intake volume being roughly equal, pressure changes are small, and the formation rate drops sharply to near zero.

[0052] When the displacement is greater than the intake volume, the pressure drops significantly, and the formation rate abruptly changes from positive to negative.

[0053] The system detects the first node where the pressure change rate changes abruptly, defines the pressure corresponding to that node as the opening pressure P0 of the pressure relief valve, and records the time T1 from when the pressure relief valve actually opens to when the system determines that it has opened.

[0054] Close the intake and stabilize the monitoring: Once the system detects that the pressure relief valve is open, immediately close the intake solenoid valve 4 and wait for a period of time until the pressure and temperature in the test tank 5 are completely stable. At this time, record the pressure P1 (unit: Pa) and temperature T1 (unit: °C) in the test tank 5.

[0055] Calculate the gas volume V1 under standard conditions: According to the ideal gas law PV=nRT, where P represents pressure (Pa in SI units, e.g., standard atmospheric pressure is approximately 101325 Pa), V is volume (m³), n is amount of substance (mol), R is the universal gas constant (approximately 8.314 J / (mol·K), and T is thermodynamic temperature (K). The volume V1 under the condition of 20℃ (thermodynamic temperature 293.15 K) is calculated using the following formula:

[0056] V1=(P1+101325)×0.25×293.15 / [(T1+273.15)×101325]

[0057] In the formula, 0.25 is the volume of test tank 5 (unit: m³), ​​and T1+273.15 is the thermodynamic temperature corresponding to the temperature during the test (unit: K).

[0058] Second test:

[0059] Replace the sealing cap: Remove the pressure relief valve on the calibration bench and replace it with a sealing cap with the same volume as the pressure relief valve cavity. Ensure that the sealing cap is sealed to the test tank 5 to ensure that the test conditions are consistent with the first test.

[0060] Maintain test conditions: Adjust the pressure inside the gas storage tank 2 and the outlet pressure reducing valve 3 to make them exactly the same as the pressure parameters during the first test, ensuring consistency of the test environment.

[0061] Intake and Pressure Monitoring: The system automatically controls the opening of the intake solenoid valve 4 and uses the high-frequency pressure sensor 6 to monitor the pressure change inside the test tank 5 in real time. When the system detects that the pressure inside the test tank 5 reaches the opening pressure P0 determined in the first test, the timer is started.

[0062] Intake closure and stability monitoring: When the timer reaches the time T1 recorded in the first test, the system immediately controls the intake solenoid valve 4 to close, waits for a period of time until the pressure and temperature in the test tank 5 are completely stable, and records the pressure P2 (unit: Pa) and temperature T2 (unit: °C) in the test tank 5 at this time.

[0063] Calculate the gas volume V2 under standard conditions: Similarly, using the ideal gas law PV=nRT, calculate the volume V2 of the gas in test tank 5 under standard atmospheric pressure (101325 Pa) and temperature of 20℃ (thermodynamic temperature 293.15 K). The calculation formula is as follows:

[0064] V2=(P2+101325)×0.25×293.15 / [(T2+273.15)×101325]

[0065] In the formula, the meaning of each parameter is consistent with the calculation formula for V1.

[0066] Displacement calculation:

[0067] By calculating the difference between V1 obtained in the second test and V1 obtained in the first test (i.e., V2-V1), the volume of gas discharged by the pressure relief valve under test in the first test, from the moment of opening to the complete closure of the intake solenoid valve 4, is obtained under standard atmospheric pressure (101325Pa) and temperature of 20℃. This volume is the discharge capacity of the pressure relief valve under test.

[0068] This test method, through two comparative tests (first with the pressure relief valve installed, second with the sealing cap installed), can effectively offset the influence of the following factors on displacement calculation: First, the time delay in the opening or closing of the intake solenoid valve 4 results in an additional amount of gas entering the test tank 5; second, when the pressure relief valve is opened, the additional amount of gas entering the test tank 5 through the intake port during the time difference between the system's recognition and judgment of the opening pressure, thereby improving the accuracy of the displacement test results.

[0069] This invention calculates the pressure change rate within test tank 5 in real time. Based on the point of sudden drop in the rate of change, the exhaust behavior immediately alters the pressure change pattern within test tank 5. Regardless of the displacement, the rate of change will exhibit a significant abrupt change. This abrupt change point is almost synchronous with the actual start of exhaust by the valve, with a lag of only the sampling interval of the high-frequency sensor, typically on the order of milliseconds. This "effect-correlation judgment" can accurately pinpoint the critical moment when the valve transitions from "closed" to "open for exhaust," ensuring that the recording error of the opening moment T1 is minimized. This provides an accurate time reference for subsequent displacement calculations and avoids deviations in intake volume calculation caused by lag in moment judgment.

[0070] In this invention, unless otherwise explicitly specified and limited, for example, it can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two elements or an interaction between two elements. Unless otherwise explicitly limited, those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0071] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A pressure relief valve discharge testing device, characterized in that: include, The gas source and the test tank are provided. The gas source is suitable for providing test pressure. A pressure reducing valve and a solenoid valve are provided between the gas source and the test tank. The outlet pressure range of the pressure reducing valve is 400-500 kPa. The test tank is suitable for installing the pressure relief valve to be tested. The test tank is also equipped with a pressure sensor for monitoring pressure and a temperature sensor for monitoring temperature.

2. The pressure relief valve discharge test device as described in claim 1, characterized in that: The air source includes an air compressor and an air storage tank connected to the output end of the air compressor.

3. The pressure relief valve discharge device as described in claim 2, characterized in that: The volume of the gas storage tank is not less than 150L, ​​and the gas storage pressure range is 700-800kPa.

4. The pressure relief valve discharge test device as described in claim 1, characterized in that: The pressure sensor is a high-frequency dynamic pressure sensor with a response frequency of not less than 20kHz and a range of 0 to 300kPa.

5. A method for testing the discharge capacity of a pressure relief valve, applicable to the pressure relief valve discharge capacity testing apparatus as described in any one of claims 1-4, characterized in that, The method includes: Clamp the pressure relief valve to be tested onto the test tank, ensuring a tight seal between the pressure relief valve and the test tank. Turn on the air intake and pressure regulation, turn on the air compressor to supply air into the air tank, and adjust the pressure reducing valve at the outlet of the air tank to make the pressure inside the test tank rise steadily. Real-time monitoring and recording, and real-time calculation of the pressure change rate inside the test tank; Determine the opening pressure and record the time. When the pressure inside the test tank changes significantly, the pressure corresponding to that node is set as the opening pressure P0 of the pressure relief valve, and the time t1 from the actual opening of the pressure relief valve to the system determining that it is open is recorded. After the intake and stability monitoring are turned off, the solenoid valve is turned off when the system determines that the pressure relief valve is open, until the pressure and temperature in the test tank are stable. At this time, the pressure P1 and temperature T1 in the test tank are recorded. Remove the pressure relief valve and seal the test container. Repeat the above steps until the pressure inside the test container reaches P0. Continue to supply air and maintain this pressure for time t1. Close the solenoid valve until the pressure and temperature inside the test container stabilize. At this point, record the pressure P inside the test container. ２ and temperature T ２ ; Calculate the gas volumes V1 and V in the test tank. ２ Based on the perfect gas law PV=nRT, calculate the volumes V1 and V of the gas inside the test vessel at standard atmospheric pressure and a temperature of 20°C. ２， The displacement of the pressure relief valve under test is obtained by calculating the difference between V2 and V1.

6. The pressure relief valve discharge test method as described in claim 5, characterized in that: During the inlet opening and pressure regulation steps, the pressure inside the test tank steadily increases at a rate of 25–40 kPa / s.

7. The pressure relief valve discharge test method as described in claim 5, characterized in that: In the real-time monitoring and recording step, the pressure sensor collects pressure change data inside the test tank in real time, and the timer records the corresponding time synchronously. Based on the pressure and time data, the pressure change rate inside the test tank is calculated in real time.

8. The pressure relief valve discharge test method as described in claim 5, characterized in that: In the steps of determining the opening pressure and recording time, when the pressure relief valve reaches the opening pressure, the pressure relief valve opens and releases gas, at which point the pressure inside the test tank changes significantly.

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