Liquefied gas filling production leak-proof automatic detection method

Abstract

The invention discloses an automatic leak-proof detection method for liquefied gas filling production, which is used for timely finding and processing leakage conditions and improving the reliability of leakage judgment and the production safety. A temperature acquisition device is arranged at the leakage point to acquire the temperature value of the leakage point in real time; the temperature variation T of the current temperature acquisition time point is calculated at each temperature acquisition time point, and in each leakage detection period, the temperature variation trend in the current leakage detection period is obtained according to the real-time temperature variation T of each temperature acquisition time point in the current leakage detection period; and judging whether leakage is generated or not according to the temperature change trend. According to the method, the principle that the temperature of leaked gas is different from the atmospheric environment temperature, and when leakage occurs, the environment temperature changes is utilized, the automatic detection function is achieved through an indirect method of measuring the temperature of a temperature collecting device installed on a leakage source, interference factors caused by environment temperature changes are eliminated, and the leakage detection accuracy is improved. Accident risks caused by gas leakage are prevented, and the production efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of bottled liquefied gas filling, and more particularly to an automatic anti-leakage detection method for liquefied gas filling production. Background Art

[0002] During the bottled liquefied gas filling process, the filling gun can misalign the gas inlet of the cylinder due to deformation caused by the age of the cylinder, or misalignment caused by improper positioning of the cylinder on the production line. This can lead to liquefied gas leakage between the cylinder inlet and the filling gun muzzle, posing serious safety hazards such as explosion and poisoning. Gas leaks also increase production costs. Currently, manual visual inspection is often relied upon. When employees fail to detect these issues in a timely manner, LPG leaks can occur, resulting in fuel waste and pollution. More seriously, these leaks can become a fire hazard, and failure to properly prevent them can lead to serious accidents.

[0003] The traditional method is to determine whether a leak has occurred through a direct method, that is, using a sensor to measure the gas being measured (i.e., the filling gas). Regardless of the detection principle (semiconductor, catalytic combustion, etc.), the gas sensor has certain defects in gas response time, sensor recovery time, and high-concentration flooding of the sensor. It is not suitable for real-time automatic leak detection of bottled liquefied gas. Therefore, the automatic detection function has not yet been realized in this field. Summary of the Invention

[0004] The purpose of the present invention is to address the technical defects existing in the prior art and provide an automatic detection method for leak prevention in liquefied gas filling production. By using an indirect method, the temperature of the leakage point is detected to obtain the real-time temperature or temperature change trend, thereby realizing the automatic detection function, timely discovering and processing the leakage, improving the reliability of leakage judgment, and improving the safety of filling production.

[0005] The technical solution adopted to achieve the purpose of the present invention is: A method for automatically detecting leakage in liquefied gas filling production is provided. A temperature acquisition device is provided at the leakage point to collect the temperature value of the leakage point in real time. Whether leakage occurs is determined based on the real-time temperature or the detected temperature change value.

[0006] The method for determining whether leakage occurs includes any one of method A, method B and method C; Method A is to judge according to the lower limit set value of temperature: at the temperature collection time point, the real-time temperature at the current temperature collection time point is compared with the lower limit set value of temperature. If the current real-time temperature is less than the lower limit set value of temperature, it is judged that a leak occurs; Method B is to judge based on the temperature change trend: at each temperature collection time point, the real-time temperature change ΔT at the current temperature collection time point is obtained. In each leak detection cycle, the temperature change trend within the current leak detection cycle is obtained based on the real-time temperature change ΔT at each temperature collection time point within the current leak detection cycle, and whether a leak occurs is judged based on the temperature change trend; Method C is to judge according to the temperature change ΔT: obtain the real-time temperature change ΔT at each temperature collection time point, and judge whether a leak occurs based on the comparison of the real-time temperature change ΔT with the temperature change set value.

[0007] The method B comprises the following steps: (1) Real-time temperature collection: collect the real-time temperature value of the leakage point according to the preset temperature collection time point; (2) Obtaining real-time temperature change: Compare the real-time temperature data at the current temperature collection time point with the real-time temperature data at the previous temperature collection time point to obtain the real-time temperature change ΔT at the current temperature collection time point; (3) Leakage cycle judgment: judge whether the preset leakage detection cycle is reached. If the preset leakage detection cycle is reached, the change trend of the temperature change in the current leakage detection cycle is obtained based on the real-time temperature change △T at each temperature collection time point in the current leakage detection cycle. If the change trend is a continuous downward trend, it is judged that a leak has occurred.

[0008] The temperature values ​​collected by the methods A, B and C are filtered to eliminate distortion caused by interference of the electrical signal.

[0009] In the method A, if a leak occurs, a leak alarm is issued. After the leak alarm, the alarm valve closing interlock and maintenance and interlock release subroutine are entered, and the following steps are performed: the real-time temperature value of the leakage point is collected in real time and filtered. When the real-time temperature is obtained ≥ the lower limit temperature set value, it is judged that the leakage is completely controlled.

[0010] In the method B, if a leak occurs, a leak alarm is issued. After the leak alarm, the alarm valve closing interlock and post-maintenance and interlock release subroutine is entered, and the following steps are performed: the real-time temperature value of the leak point is collected according to the preset temperature collection time point and filtered, and the real-time temperature change ΔT at the current temperature collection time point is obtained; based on the real-time temperature change ΔT at each temperature collection time point, the change trend of the temperature change is obtained. If the change trend is a continuous upward trend, it is determined that the leakage is gradually controlled until the upward change trend turns into a gentle trend, and it is determined that the leakage is completely controlled.

[0011] The interval between two adjacent temperature collection time points is 10-50 milliseconds, and the leakage detection cycle is 0.1-1 second.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The control method of the present invention utilizes the principle that the temperature of the leaking gas is different from the ambient temperature, and the ambient temperature changes when a leak occurs. By measuring the temperature acquisition device installed at the leak source, it is possible to detect whether the gas is leaking and make a leak judgment. The real-time automatic detection function is achieved through an indirect method, and the leakage can be discovered and handled in time, thereby improving the reliability of the leakage judgment and improving the safety of the filling production.

[0013] 2. The control method of the present invention collects the temperature of a temperature acquisition device installed at the leak point in real time and compares it with the temperature value collected in the previous cycle to determine the temperature change ΔT at the leak point. The method then determines the trend of this temperature change within the leak detection cycle to determine whether a leak has occurred. This method eliminates interfering factors that affect ambient temperature fluctuations (such as winter and summer, morning and evening), effectively detecting temperature changes detected by the sensor caused by actual liquefied gas leaks, resulting in more accurate detection. This method achieves safe control of filling automation, prevents accident risks caused by gas leaks, improves production safety, and eliminates production downtime caused by gas leaks, thereby increasing production efficiency.

[0014] 3. The control method of the present invention determines whether the gas leakage has been controlled by the trend of temperature change during the maintenance and interlock release period after the alarm valve is closed, and realizes the linkage quick unlocking function, so that the maintenance personnel can manually start the equipment at any time to resume normal production after the problem is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Shown is a schematic diagram of the leak point; Figure 2 The figure shows the trend of ambient temperature change in the filling workshop; Figure 3 The figure shows the schematic diagram of the temperature acquisition device detection before and after gas leakage; Figure 4 The diagram shows a case with no gas leakage; Figure 5 The diagram shows that the leakage has been linked and controlled; Figure 6 Shown is the leak detection schematic. DETAILED DESCRIPTION

[0016] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0017] The method of the present invention utilizes the physical properties of liquefied gas during the filling process (the temperature of liquefied gas is -40°C) and the principle that the temperature of the surrounding gas changes at the moment of filling leakage to determine whether there is leakage.

[0018] The following is a specific example of a leak point at the interface between the filling gun and the cylinder angle valve. The same method can be used to determine the leak point at other locations.

[0019] The schematic diagram of the leakage point in this embodiment is as follows Figure 1 As shown, the device comprises a liquefied gas cylinder 1, an angle valve 2, a filling gun head 3, a temperature acquisition device 4, and an alarm 5. The leakage point between the filling gun head 3 and the cylinder angle valve 2 is considered as the leakage point, and a temperature acquisition device 4 is provided at the leakage point. In this embodiment, the temperature acquisition device is a temperature sensor.

[0020] Leakage schematic diagram Figure 6 As shown in the figure, propane, the main component of liquefied petroleum gas, has a boiling point of -42°C. When leaking gas flows in the direction of the arrow in the figure, the liquefied petroleum gas released into the atmosphere rapidly vaporizes. The more intense the vaporization, the faster it absorbs heat, causing the ambient temperature in the area of ​​release to drop rapidly. The local temperature near the leak point can drop to near the boiling point of propane, but depending on the amount of leakage and its distance from the valve port, it can reach a minimum of -20°C to -30°C or even lower. The microcontroller detects gas leaks by measuring the resistance change of the temperature sensor RT installed at the leak point. At test point A, the microcontroller uses A / D sampling to measure the voltage change at point A and determine the resistance change of the temperature sensor RT. When a leak occurs, a control signal is transmitted to the alarm, which then outputs an alarm and linkage signal.

[0021] The automatic detection method for preventing leakage in liquefied gas filling production of the present invention comprises the following steps: Install the filling gun, connect the filling gun tip to the cylinder angle valve, open the filling valve, and fill the cylinder with fluid. The temperature of the temperature acquisition device installed at the leak point is collected in real time; based on the real-time temperature or the detected temperature change value, it is determined whether a leak has occurred.

[0022] The method for determining whether leakage occurs includes any one of method A, method B and method C; Method A uses the lower temperature setpoint as the basis for judgment: at the temperature collection time point, the real-time temperature at that point is compared with the lower temperature setpoint. If the current real-time temperature is less than the lower temperature setpoint, a leak is determined to have occurred, and a leak alarm is issued. To determine the control status of the leak, after the leak alarm is issued, the alarm valve closing interlock post-maintenance and interlock release subroutine is executed, performing the following steps: real-time temperature values ​​at the leak point are collected and filtered. If the real-time temperature is greater than or equal to the lower temperature setpoint, the leak is determined to be fully controlled.

[0023] When liquefied petroleum gas leaks, it vaporizes rapidly and absorbs heat, causing the temperature near the valve nozzle to drop sharply. The temperature approaches the boiling point of propane, the main component of liquefied petroleum gas, which is around -42 degrees Celsius. Considering that the sensor probe is a little distance away from the interface, the lower limit temperature setting value will generally be set higher than this. The higher the value, the more sensitive it is, but it must be lower than the ambient temperature.

[0024] Figure 2 The figure shows the trend of ambient temperature changes in the filling workshop. The ambient temperature is different in spring, summer, autumn and winter. The ambient temperature in the morning and evening also changes slowly. During the test, it is necessary to eliminate the interference factors of ambient temperature changes (such as winter and summer, morning and evening, etc.) (Note: the temperature changes slowly).

[0025] Due to the interference of ambient temperature changes (such as winter and summer, morning and night, etc.), the judgment method based solely on the lower limit temperature setting value is prone to missed judgments or misjudgments. Moreover, if the lower limit temperature setting value is used alone, after a leak is manually set, the temperature will slowly rise and production cannot be resumed immediately, affecting production efficiency. Therefore, the temperature change △T is used for judgment to avoid the influence of interference factors.

[0026] Method B is based on temperature change trends: Calculate the temperature change ΔT at each temperature collection time point. In each leak detection cycle, the temperature change trend within the current leak detection cycle is obtained based on the real-time temperature change ΔT at each temperature collection time point within the current leak detection cycle. Determine whether a leak has occurred based on the temperature change trend. The specific steps are as follows: (1) Real-time temperature collection: collect the real-time temperature value of the leakage point according to the preset temperature collection time point; (2) Obtaining real-time temperature change: Compare the real-time temperature data at the current temperature collection time point with the real-time temperature data at the previous temperature collection time point to obtain the real-time temperature change ΔT at the current temperature collection time point; (3) Leakage period judgment: judging whether the preset leakage detection period is reached, if the preset leakage detection period is reached, the temperature variation trend in the current leakage detection period is obtained according to the real-time temperature variation ΔT of each temperature collection time point, if the variation trend is continuous downward trend, it is judged that leakage occurs. If leakage occurs, leakage alarm is performed. In order to judge the control situation of leakage, after leakage alarm, alarm valve closing interlocking and maintenance and interlocking release subprogram are entered, the following steps are performed: collecting real-time temperature value of leakage point according to preset temperature collection time point and performing filtering processing, and obtaining real-time temperature variation ΔT of current temperature collection time point; obtaining temperature variation trend according to real-time temperature variation ΔT of each temperature collection time point, if the variation trend is continuous upward trend, it is judged that leakage is gradually controlled, until the upward variation trend changes into gentle trend, it is judged that leakage is completely controlled. After maintenance personnel solves the problem, the equipment is manually started to restore normal production at any time.

[0027] The method C is to judge according to temperature variation ΔT: obtaining real-time temperature variation ΔT of current temperature collection time point at each temperature collection time point, and judging whether leakage occurs according to comparison between real-time temperature variation ΔT and temperature variation lower limit set value. The temperature variation lower limit set value can be obtained through experiment according to actual production situation. When real-time temperature variation ΔT is greater than temperature variation lower limit set value, it is judged that leakage occurs, and leakage alarm is performed.

[0028] The temperature values collected by the method A, the method B and the method C are filtered to eliminate distortion caused by interference of electric signal.

[0029] In the embodiment, interval of adjacent two temperature collection time points is 10-50 milliseconds, and leakage detection period is 0.1-1 second. Embodiment

[0030] The leakage detection schematic diagram is shown in Figure 6 When liquefied petroleum gas leaks during filling, it will rapidly gasify, which will cause the ambient temperature around the leakage point to sharply drop. Through change of resistance value of temperature sensor RT installed at the leakage point, single-chip microcomputer judges resistance value change of the temperature sensor through voltage change of A point in test point A, so as to achieve the purpose of gas leakage detection.

[0031] With interval of adjacent temperature collection time points being 50 milliseconds and leakage collection period being 1 second, temperature data is collected every 50 milliseconds, and real-time filtered temperature data is obtained through filtering according to conventional filtering method. And it is stored in single-chip microcomputer. When measured temperature variation is as shown in Figure 3 , it is judged as gas leakage. When measured data is as shown in Figure 4If the measured data is as shown, it is considered that there is no gas leakage. Figure 5 When shown, it is considered that the leakage has been linked and controlled, and the temperature acquisition device is recovering.

[0032] After repeated tests and verification, the method of the present invention has been found to be effective.

[0033] The control method of the present invention utilizes the principle that the temperature of leaking gas differs from the ambient temperature, causing a change in ambient temperature when a leak occurs. By measuring the temperature of a temperature acquisition device installed at the leak source, gas leaks are detected and leak determination is performed, thus achieving automatic detection. By comparing the real-time temperature of the temperature acquisition device installed at the leak with the temperature value collected in the previous cycle, the measured temperature change ΔT is determined. The trend of this change within the leak detection cycle is then determined to determine whether a leak has occurred. This eliminates interference factors caused by ambient temperature fluctuations (such as winter and summer, morning and evening, etc.) (Note: temperature changes slowly), thereby detecting ambient temperature changes caused by actual liquefied gas leaks and making detection more accurate. This achieves safe control of automated filling, prevents accident risks caused by gas leaks, improves production safety, and mitigates production downtime caused by gas leak handling, thereby increasing production efficiency.

[0034] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for automatically detecting leakage in liquefied gas filling production, characterized in that: A temperature acquisition device is set at the leakage point to collect the temperature value of the leakage point in real time; whether a leakage occurs is determined based on the real-time temperature or the detected temperature change value.

2. The automatic detection method for preventing leakage in liquefied gas filling production according to claim 1 is characterized in that: The method for determining whether leakage occurs includes any one of method A, method B and method C; Method A is to judge according to the lower limit set value of temperature: at the temperature collection time point, the real-time temperature at the current temperature collection time point is compared with the lower limit set value of temperature. If the current real-time temperature is less than the lower limit set value of temperature, it is judged that a leak occurs; Method B is to judge based on the temperature change trend: at each temperature collection time point, the real-time temperature change ΔT at the current temperature collection time point is obtained. In each leak detection cycle, the temperature change trend within the current leak detection cycle is obtained based on the real-time temperature change ΔT at each temperature collection time point within the current leak detection cycle, and whether a leak occurs is judged based on the temperature change trend; Method C is to judge according to the temperature change ΔT: obtain the real-time temperature change ΔT at each temperature collection time point, and judge whether a leak occurs based on the comparison of the real-time temperature change ΔT with the temperature change set value.

3. The automatic anti-leakage detection method for liquefied gas filling production according to claim 2 is characterized in that: The method B comprises the following steps: (1) Real-time temperature collection: collect the real-time temperature value of the leakage point according to the preset temperature collection time point; (2) Obtaining real-time temperature change: Compare the real-time temperature data at the current temperature collection time point with the real-time temperature data at the previous temperature collection time point to obtain the real-time temperature change ΔT at the current temperature collection time point; (3) Leakage cycle judgment: judge whether the preset leakage detection cycle is reached. If the preset leakage detection cycle is reached, the change trend of the temperature change in the current leakage detection cycle is obtained based on the real-time temperature change △T at each temperature collection time point in the current leakage detection cycle. If the change trend is a continuous downward trend, it is judged that a leak has occurred.

4. The automatic anti-leakage detection method for liquefied gas filling production according to claim 2 or 3, characterized in that: The temperature values ​​collected by the methods A, B and C are filtered to eliminate distortion caused by interference of the electrical signal.

5. The automatic anti-leakage detection method for liquefied gas filling production according to claim 2 is characterized in that: In the method A, if a leak occurs, a leak alarm is issued. After the leak alarm, the alarm valve closing interlock and maintenance and interlock release subroutine are entered, and the following steps are performed: the real-time temperature value of the leakage point is collected in real time and filtered. When the real-time temperature is obtained ≥ the lower limit temperature set value, it is judged that the leakage is completely controlled.

6. The automatic anti-leakage detection method for liquefied gas filling production according to claim 2 or 3, characterized in that: In the method B, if a leak occurs, a leak alarm is issued. After the leak alarm, the alarm valve closing interlock and post-maintenance and interlock release subroutine is entered, and the following steps are performed: the real-time temperature value of the leak point is collected according to the preset temperature collection time point and filtered, and the real-time temperature change ΔT at the current temperature collection time point is obtained; based on the real-time temperature change ΔT at each temperature collection time point, the change trend of the temperature change is obtained. If the change trend is a continuous upward trend, it is determined that the leakage is gradually controlled until the upward change trend turns into a gentle trend, and it is determined that the leakage is completely controlled.

7. The automatic anti-leakage detection method for liquefied gas filling production according to claim 3 is characterized in that: The interval between two adjacent temperature collection time points is 10-50 milliseconds, and the leakage detection cycle is 0.1-1 second.

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