A device for detecting leakage of gasoline and diesel oil based on capacitance method

Abstract

The utility model relates to liquid leakage detection technical field discloses a gasoline and diesel oil leakage detection device based on electric capacity method. It aims at solving the technical problem that the float dry spring tube method can not detect internal oil product leakage and still external underground water leakage in prior art. The utility model discloses sensor probe, the sensor probe includes two parallel copper electrodes of setting, is used to form the inductive capacitance with the medium in the environment of detection, sensor probe electric connection capacity frequency conversion circuit is used for converting the capacitance value change of inductive capacitance into corresponding frequency signal, the capacity frequency conversion circuit is the no steady state multivibrator of NE555 timer constitution, and the output frequency of no steady state multivibrator is inversely proportional with the capacity of inductive capacitance. The utility model can realize detecting oil tank, the oil product leakage in pipe or external liquid oil unloading, and precision is high, can detect tiny leakage, and can also detect the narrow oil tank interlayer.

Description

Technical Field

[0001] This utility model relates to the field of liquid leakage detection technology, and in particular to a gasoline and diesel leakage detection device based on the capacitance method. Background Technology

[0002] In petrochemical plants, gas stations, oil depots, tank trucks, and various locations using gasoline and diesel as power or fuel, gasoline and diesel leaks pose a significant safety and environmental hazard. Leaks not only cause direct economic losses, but the resulting oil and gas vapors also pose risks of combustion and explosion, and severely pollute soil and groundwater. Currently, there are several technical approaches for monitoring gasoline and diesel leaks. Manual inspection relies on periodic patrols by personnel, which is inefficient and cannot achieve real-time monitoring. Pressure / flow monitoring methods infer leaks by analyzing parameter changes within the pipeline system, but are insensitive to small, slow leaks and are easily affected by normal operating conditions. Optical / acoustic detection methods, such as oil and gas sensors or ultrasonic leak detectors, offer high accuracy, but the equipment is typically complex in structure, expensive, and its performance is susceptible to environmental factors. Furthermore, simple and low-cost resistive sensors are also used, but they typically only enable fixed-point, on / off detection, unable to detect early, minute leaks, and the electrodes are prone to scaling and corrosion over long-term use.

[0003] Gas station oil storage and oil and gas pipeline connections are all buried underground, which has advantages such as convenient maintenance, safety, and small footprint. However, it has the problem of undetectable leaks. Previously, oil tanks used steel with an outer protective layer, which posed a risk of corrosion and leakage. Since 2017, a double-layer structure has been required, including double-layer pipelines. If a leak occurs, it first leaks to the middle layer, preventing soil contamination; then, technical means are used to detect the leak promptly and take remedial measures. This involves double-layer pipeline and double-layer tank leak detectors. The principle is that when liquid leaks, the liquid moves a float upwards. When it passes a reed switch, the permanent magnet inside the float affects the reed switch's opening and closing, thus detecting the leak. Based on this principle, it is clear that the float-reed switch method cannot detect internal oil leaks or external groundwater leaks.

[0004] Therefore, there is an urgent need to propose a gasoline and diesel leak detection device based on the capacitance method. Summary of the Invention

[0005] In view of the above technical problems, this disclosure provides a gasoline and diesel leak detection device based on the capacitance method, which solves the technical problem that the float reed switch method in the prior art cannot detect whether the leak is internal oil or external groundwater. It is applied to the interlayer space of double-walled oil tanks or double-walled pipelines in gas stations to detect whether the leak is oil, groundwater seepage, or condensation. By identifying the dielectric constant of the medium corresponding to the output frequency, it distinguishes and detects different types of liquids, including gasoline and diesel with a dielectric constant of 2, groundwater with a dielectric constant of 15, and air condensation with a dielectric constant of 80.

[0006] According to one aspect of this disclosure, a gasoline / diesel leak detection device based on capacitance method is provided, including a sensor probe, the sensor probe including two parallel copper electrodes for forming an induced capacitance with the medium in the environment to be detected; The sensor probe is electrically connected to a capacitance-frequency conversion circuit, which is used to convert the change in capacitance of the sensing capacitor into a corresponding frequency signal. The capacitance-frequency conversion circuit is an astable multivibrator composed of an NE555 timer. The output frequency of the astable multivibrator is inversely proportional to the capacitance of the sensing capacitor.

[0007] In some embodiments of this disclosure, the sensor probe has a diameter of 1 cm to accommodate confined installation spaces.

[0008] In some embodiments of this disclosure, the sensor probe is encapsulated in a probe sealant, the capacitance-frequency conversion circuit is encapsulated in a circuit board sealant, and the probe sealant and circuit board sealant are mounted in a housing.

[0009] In some embodiments of this disclosure, the probe sealant is an oleophobic fluoropolymer material.

[0010] In some embodiments of this disclosure, the capacitance-frequency conversion circuit further includes a temperature sensor for acquiring ambient temperature; the capacitance-frequency conversion circuit and the temperature sensor are electrically connected to a microprocessor for receiving frequency signals and temperature data, and compensating the frequency signals based on a temperature-frequency compensation relationship to eliminate the influence of ambient temperature changes on capacitance measurement.

[0011] In some embodiments of this disclosure, the positive and negative power input terminals of the NE555 timer are connected to a power supply; the reset terminal of the NE555 timer is connected to a pull-up resistor R1; the control voltage terminal of the NE555 timer is connected to a capacitor C2 to stabilize the internal reference voltage; the trigger terminal and threshold terminal of the NE555 timer are interconnected and jointly connected to capacitor C1 and resistor R2 to output a pulse signal.

[0012] In some embodiments of this disclosure, the capacitance of capacitor C1 is 10 Nf, the resistance of resistor R2 is 6.2 KΩ, the resistance of resistor R1 is 1 KΩ, and the capacitance of capacitor C2 is 10 nF.

[0013] The beneficial effects of this utility model are as follows: It can detect oil leaks in tanks and pipes or external liquid unloading with high accuracy, capable of detecting even minute leaks. It provides continuous detection, and the float-based system only detects leaks when the float moves. It is small in size (1cm diameter), allowing detection even in narrow tank compartments. It is also low-cost, utilizing mature components and technologies available on the market. A capacitance-to-frequency conversion circuit based on the NE555 timer is used to directly convert minute capacitance changes sensed by the sensor probe into frequency signals. Frequency signals have the advantages of strong anti-interference ability, ease of transmission and measurement, and can sensitively capture changes in dielectric constant caused by gasoline and diesel leaks, achieving fast and highly sensitive real-time monitoring.

[0014] The sensor probe adopts a parallel copper electrode design and has a diameter of only 1 cm. Its miniaturized design allows it to be easily installed in narrow spaces such as tank gaps and pipe interfaces, where traditional sensors are difficult to place, greatly expanding the applicable scenarios of the device.

[0015] Multiple layers of protection are achieved by encapsulating the sensor probe and the capacitance-frequency conversion circuit separately with sealant and placing them inside a housing. The probe sealant uses an oleophobic fluoropolymer material, which not only effectively resists the corrosion and adhesion of gasoline and diesel fuel, preventing the sensor performance from deteriorating due to oil contamination, but also possesses excellent chemical stability and hydrophobicity, ensuring the long-term stable operation and service life of the probe in harsh industrial environments.

[0016] A temperature sensor, combined with a microprocessor, is used to construct a temperature compensation mechanism. By using a pre-calibrated temperature-frequency relationship, the output frequency of the capacitance-frequency conversion circuit is compensated in real time, effectively eliminating the systematic errors caused by ambient temperature fluctuations in capacitance measurement and subsequent judgment. This significantly improves the measurement accuracy and reliability of the entire device under different seasons and operating conditions, and greatly reduces the false alarm and missed alarm rates.

[0017] Ordinary encapsulating adhesives can be soaked in gasoline or diesel fuel or swell, causing a shift in dielectric constant and resulting in measurement errors. Using oleophobic fluoropolymers actively repels oils, preventing oil molecules from penetrating the encapsulant or adhering to the surface, thus ensuring the long-term stability and measurement accuracy of the sensor.

[0018] The capacitance value is greatly affected by temperature, and simply measuring the frequency can produce false alarms due to changes in ambient temperature. By adding temperature sensing and compensation techniques, the temperature drift problem is solved, significantly improving the reliability and accuracy of the detection. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a gasoline and diesel leak detection device based on the capacitance method. Figure 2 This is a schematic diagram of the exploded structure of a gasoline and diesel leak detection device based on the capacitance method. Figure 3 This is a schematic diagram of a capacitance-frequency conversion circuit. The components in the diagram are named as follows: 1. Sensor probe; 2. Capacitor-frequency conversion circuit; 3. Probe sealing; 4. Circuit board sealing; 5. Housing. Detailed Implementation

[0020] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention. Example 1

[0021] This example discloses a gasoline / diesel leak detection device based on the capacitance method. See [link to relevant documentation]. Figures 1 to 3 The sensor probe 1 includes two parallel copper electrodes for forming an inductive capacitance with the medium in the environment to be detected. Sensor probe 1 is electrically connected to capacitance-frequency conversion circuit 2, which is used to convert the change in capacitance value of the sensing capacitor into a corresponding frequency signal. The capacitance-frequency conversion circuit 2 is an astable multivibrator composed of NE555 timer. The output frequency of the astable multivibrator is inversely proportional to the capacitance value of the sensing capacitor.

[0022] The sensor probe 1 has a diameter of 1 cm to accommodate small installation spaces.

[0023] The sensor probe 1 is encapsulated in the probe sealant 3, the capacitance-frequency conversion circuit 2 is encapsulated in the circuit board sealant 4, and the probe sealant 3 and the circuit board sealant 4 are installed in the housing 5.

[0024] The probe sealant 3 is made of an oleophobic fluorinated polymer material.

[0025] The capacitance-frequency conversion circuit 2 also includes a temperature sensor for acquiring ambient temperature. The capacitance-frequency conversion circuit and the temperature sensor are electrically connected to the microprocessor for receiving frequency signals and temperature data, and for compensating the frequency signal based on the temperature-frequency compensation relationship to eliminate the influence of ambient temperature changes on capacitance measurement.

[0026] The positive and negative power input terminals of the NE555 timer are used to connect to the power supply; the reset terminal of the NE555 timer is connected to the pull-up resistor R1; the control voltage terminal of the NE555 timer is connected to the capacitor C2 to stabilize the internal reference voltage; the trigger terminal and threshold terminal of the NE555 timer are interconnected and connected together to the capacitor C1 and the resistor R2 to output a pulse signal.

[0027] The capacitance of capacitor C1 is 10 NF, the resistance of resistor R2 is 6.2 KΩ, the resistance of resistor R1 is 1 KΩ, and the capacitance of capacitor C2 is 10 nF.

[0028] During operation, sensor probe 1 is placed in the area to be monitored, and the two parallel copper electrodes together with the surrounding medium form an inductive capacitor. When no leakage occurs, the medium around the probe is air, which has the lowest dielectric constant, and the capacitance value of the inductive capacitor remains at a low reference value. The inductive capacitor is one of the key external timing components of the capacitance-frequency conversion circuit 2 (NE555 astable multivibrator). The output frequency of the oscillator is determined by the external resistor R2 and the inductive capacitor C (i.e., the capacitance formed by the probe and the medium), and the specific relationship is as follows: .

[0029] Therefore, when the capacitance C changes, the output frequency changes inversely. In the event of a gasoline / diesel leak, the leaking liquid will displace the air surrounding the probe. Since gasoline / diesel has a significantly higher dielectric constant than air, the capacitance C increases, resulting in a decrease in the output frequency signal. This frequency signal is transmitted to the microprocessor. Simultaneously, the temperature sensor collects ambient temperature data in real time. After receiving the frequency signal and temperature data, the microprocessor calls its internal temperature-frequency compensation algorithm to calibrate the currently measured frequency value, eliminating measurement errors introduced by temperature drift. Finally, the microprocessor compares and judges the compensated frequency value with preset frequency threshold ranges corresponding to air, water, and gasoline / diesel states. If the compensated frequency value stably falls within the gasoline / diesel characteristic range, the microprocessor determines that a leak has occurred and immediately activates the alarm device, thus completing a full leak detection and alarm process.

[0030] Although some preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0031] Obviously, those skilled in the art can make various modifications and variations to this utility model without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this application and their equivalents, this utility model also intends to include these modifications and variations.

Claims

1. A gasoline / diesel leak detection device based on capacitance method, characterized in that, include: A sensor probe, comprising two parallel copper electrodes for forming an inductive capacitance with the medium in the environment to be detected; The sensor probe is electrically connected to a capacitance-frequency conversion circuit, which is used to convert the change in capacitance of the sensing capacitor into a corresponding frequency signal. The capacitance-frequency conversion circuit is an astable multivibrator composed of an NE555 timer. The output frequency of the astable multivibrator is inversely proportional to the capacitance of the sensing capacitor.

2. The gasoline and diesel leak detection device based on capacitance method as described in claim 1, characterized in that: The sensor probe has a diameter of 1 cm to accommodate small installation spaces.

3. The gasoline and diesel leak detection device based on capacitance method as described in claim 1, characterized in that: The sensor probe is encapsulated in probe sealant, the capacitance-frequency conversion circuit is encapsulated in circuit board sealant, and the probe sealant and circuit board sealant are installed in the housing.

4. The gasoline and diesel leak detection device based on capacitance method as described in claim 3, characterized in that: The probe sealant is an oleophobic fluoropolymer material.

5. The gasoline and diesel leak detection device based on capacitance method as described in claim 1, characterized in that: The capacitance-frequency conversion circuit also includes a temperature sensor for acquiring ambient temperature. The capacitance-frequency conversion circuit and the temperature sensor are electrically connected to a microprocessor for receiving frequency signals and temperature data, and for compensating the frequency signal based on the temperature-frequency compensation relationship to eliminate the influence of ambient temperature changes on capacitance measurement.

6. The gasoline and diesel leak detection device based on capacitance method as described in claim 1, characterized in that: The positive and negative power input terminals of the NE555 timer are used to connect to the power supply; the reset terminal of the NE555 timer is connected to a pull-up resistor R1; the control voltage terminal of the NE555 timer is connected to a capacitor C2 to stabilize the internal reference voltage; the trigger terminal and threshold terminal of the NE555 timer are interconnected and jointly connected to a capacitor C1 and a resistor R2 to output a pulse signal.

7. The gasoline and diesel leak detection device based on capacitance method as described in claim 6, characterized in that: The capacitance of capacitor C1 is 10 Nf, the resistance of resistor R2 is 6.2 KΩ, the resistance of resistor R1 is 1 KΩ, and the capacitance of capacitor C2 is 10 nF.

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