Liquid level monitoring device and monitoring method

Abstract

The present invention provides a liquid level monitoring device and a monitoring method. The device includes: a first temperature sensing optical cable for being laid in a liquid to be measured and perpendicular to the liquid level of the liquid to be measured, with at least a part of the first temperature sensing optical cable exposed above the liquid level of the liquid to be measured. Wherein, the first end of the first temperature sensing optical cable is located below the liquid level of the liquid to be measured, and the second end of the first temperature sensing optical cable is connected to an optical fiber demodulation device; the optical fiber demodulation device is configured to collect optical signals at multiple preset positions on the first temperature sensing optical cable at a preset sampling interval to obtain Raman scattering parameters of the optical signals, calculate the corresponding temperature according to the Raman scattering parameters of the optical signals, and calculate the position of the liquid level of the liquid to be measured based on the temperatures at each preset position. For the monitoring device of the present application, measurement is carried out using the first temperature sensing optical cable. Since the optical cable is not charged in the liquid to be measured, potential hazards such as the fire risk caused by electric leakage are avoided; at the same time, the optical cable is less susceptible to interference from the surrounding electromagnetic field, and the measurement result is more accurate.

Description

Technical Field

[0001] The present invention relates to the technical field of storage tank monitoring, and particularly relates to a liquid level monitoring device and a monitoring method. Background Art

[0002] The monitoring of the liquid level in a storage tank refers to the real-time monitoring and management of the liquid level of the liquid in the storage tank (such as crude oil, water, chemicals, etc.) to avoid potential risks such as overflow and leakage.

[0003] The existing monitoring of the liquid level in storage tanks can generally be divided into three types: magnetostrictive liquid level gauges, radar liquid level gauges, and servo liquid level gauges. These three types of liquid level monitoring are all charged point-type measurements, which inevitably bring certain safety hazards. For example, during the charged measurement process, static electricity may be generated due to factors such as electrical contact, separation, and friction. When the static charge accumulates to a certain extent and is suddenly released, static sparks may be generated. In an environment such as an oil tank where flammable and explosive substances exist, static sparks can easily ignite the oil and gas mixture, causing a fire or explosion. In addition, the charged measurement may be interfered by the surrounding electromagnetic field, affecting the accuracy of the measurement results. This may lead to misjudgment of the liquid level height of the oil tank, thereby affecting the safety management and operation of the oil tank.

[0004] Therefore, there is a need for a liquid level monitoring device with better safety and stronger anti-interference ability at present. Summary of the Invention

[0005] Based on this, it is necessary to provide a liquid level monitoring device and a monitoring method for the above technical problems.

[0006] A liquid level monitoring device includes:

[0007] A first temperature sensing optical fiber cable, which is used to be laid in the liquid to be measured and is perpendicular to the liquid level of the liquid to be measured. At least a part of the first temperature sensing optical fiber cable is exposed above the liquid level of the liquid to be measured. Among them, the first end of the first temperature sensing optical fiber cable is located below the liquid level of the liquid to be measured, and the second end of the first temperature sensing optical fiber cable is connected to the optical fiber demodulation device;

[0008] The optical fiber demodulation device is used to collect the optical signals at multiple preset positions on the first temperature sensing optical fiber cable at a preset sampling interval to obtain the Raman scattering parameters of the optical signals, calculate the temperature corresponding to the Raman scattering parameters of the optical signals at each preset position according to the Raman scattering parameters of the optical signals, and calculate the position of the liquid level of the liquid to be measured based on the temperatures at each preset position.

[0009] In one embodiment, the preset sampling interval is less than or equal to 0.05 meters, the number of the first temperature sensing optical fiber cables is one, and the first temperature sensing optical fiber cable is laid perpendicular to the liquid level of the liquid to be measured.

[0010] In one embodiment, the number of the first temperature sensing optical cables is multiple, and the multiple first temperature sensing optical cables are laid at intervals perpendicular to the liquid level of the liquid to be measured. The optical fiber demodulation device is provided with a plurality of optical cable connection ports, and the second ends of the first temperature sensing optical cables are correspondingly connected to the optical cable connection ports.

[0011] In one embodiment, a waterproof layer is coated on the first end of the first temperature sensing optical cable.

[0012] In one embodiment, a fiber core cutoff ring is provided at the first end of the first temperature sensing optical cable.

[0013] In one embodiment, it further includes:

[0014] An alarm device, which is used to communicate with the optical fiber demodulation device and issue an alarm when the change value of the liquid level position exceeds the liquid level change threshold and / or when the temperature value corresponding to the temperature signal exceeds the temperature threshold.

[0015] In one embodiment, it further includes:

[0016] A display device, which is used to communicate with the optical fiber demodulation device and display the temperature distribution information according to the temperatures at the preset positions.

[0017] In one embodiment, the optical fiber demodulation device is further used to demodulate the acoustic vibration signal, and the device further includes:

[0018] A vibration optical cable, which is used to transmit the acoustic vibration signal generated by the gas leakage and / or liquid leakage of the liquid to be measured. The first end of the vibration optical cable is communicatively connected to a sound monitoring device, and the second end of the vibration optical cable is communicatively connected to the optical fiber demodulation device.

[0019] In one embodiment, it further includes:

[0020] A second temperature sensing optical cable, which is communicatively connected to the optical fiber demodulation device and is laid in a ring shape parallel to the liquid level above the liquid to be measured.

[0021] In one embodiment, it further includes:

[0022] A remote control terminal, which is used to communicate with the optical fiber demodulation device. The remote control terminal is loaded with preset control software, and the remote control terminal is used to remotely obtain the temperatures at the preset positions according to the preset control software.

[0023] A liquid level monitoring method includes:

[0024] Collect optical signals at multiple preset positions on a target first temperature-sensitive optical cable at a preset sampling interval. The target first temperature-sensitive optical cable is laid in the liquid to be measured and is perpendicular to the liquid level of the liquid to be measured, and at least part of the first temperature-sensitive optical cable is exposed outside the liquid level of the liquid to be measured;

[0025] Preprocess the multiple optical signals to obtain Raman scattering parameters of the optical signals, and calculate the temperature corresponding to the Raman scattering parameters of the optical signals at each preset position according to the Raman scattering parameters of the optical signals;

[0026] Calculate the position of the liquid level of the liquid to be measured based on the temperatures at each preset position.

[0027] In one embodiment, after the step of calculating the position of the liquid level of the liquid to be measured based on the temperatures at each preset position, the method further includes:

[0028] Detect whether the change value of the liquid level position within a preset time period is greater than or equal to a liquid level change threshold, and issue a first alarm when the change value of the liquid level position is greater than the liquid level change threshold;

[0029] and / or

[0030] Detect whether the temperature value is greater than a temperature threshold; issue a second alarm when the temperature value is greater than the temperature threshold.

[0031] For the above liquid level monitoring device and monitoring method, the first temperature-sensitive optical cable is installed in the liquid to be measured. Since the temperatures at different depths of the liquid to be measured are different, when the first temperature-sensitive optical cable contacts the liquid to be measured at different depths, its optical properties will change, resulting in different degrees of Raman scattering of the transmitted optical signals at different temperatures. These optical signals with different Raman scattering parameters are captured by the fiber optic demodulation device and converted into electrical signals. After the fiber optic demodulation device analyzes and processes the electrical signals, different temperature values are obtained. Then, according to the turning point of the temperature change above and below the liquid level of the liquid to be measured among different temperature values, the position of the liquid level can be determined. For the monitoring device of the present application, measurement is carried out using the first temperature-sensitive optical cable. Since the optical cable is not charged in the liquid to be measured, potential hazards such as the fire risk caused by electrical leakage are avoided. Moreover, the magnetic field itself does not directly change the frequency or intensity of light, so it does not directly affect the Raman scattering process. Therefore, after the first temperature-sensitive optical cable is installed, the Raman scattering parameters of the optical signals collected by the fiber optic demodulation device are less affected by external interference, thereby improving the measurement accuracy of the liquid level. It is worth mentioning that in the present application, the temperature-sensitive optical cable is vertically laid in the liquid to be measured, so that the amount of the temperature-sensitive optical cable used is less and the laying cost is lower.

[0032] In addition, during the process of monitoring the liquid level, the monitoring device of the present application also synchronously detects the temperature of the liquid to be measured, which helps to promptly detect abnormal temperatures and avoid fire risks. That is, the device of the present application realizes both liquid level height monitoring and temperature monitoring with the same optical cable or fiber core in the same measurement, achieving the detection of liquid level anomalies, leakage, and high-temperature risks with a more concise structure and lower cost, and is more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 FIG. is a schematic diagram of an application scenario of a liquid level monitoring device in an embodiment;

[0034] Figure 2 FIG. is a schematic diagram of a temperature distribution map in an embodiment;

[0035] Figure 3 FIG. is a schematic flowchart of a liquid level monitoring method in an embodiment;

[0036] Figure 4 FIG. is a schematic diagram of the bubble aggregation characteristics in the temperature distribution map in an embodiment;

[0037] Figure 5 FIG. is a schematic diagram of another liquid level monitoring device in an embodiment;

[0038] Figure 6 FIG. is a schematic diagram of the assembly relationship between a vibrating optical cable and an optical fiber demodulation device in an embodiment;

[0039] Figure 7 FIG. is a schematic diagram of the assembly relationship between a second temperature-sensitive optical cable and an optical fiber demodulation device in an embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0040] In order to make the objectives, technical solutions, and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0041] Embodiment 1

[0042] In this embodiment, as Figure 1 shown, a liquid level monitoring device is provided, which includes a first temperature-sensitive optical cable 110 and an optical fiber demodulation device 120, wherein:

[0043] The first temperature-sensitive optical cable 110 is used to be laid in the liquid to be measured and perpendicular to the liquid level of the liquid to be measured. At least a part of the first temperature-sensitive optical cable is exposed above the liquid level of the liquid to be measured. Among them, the first end of the first temperature-sensitive optical cable is located below the liquid level of the liquid to be measured, and the second end of the first temperature-sensitive optical cable is connected to the optical fiber demodulation device;

[0044] An optical fiber demodulation device 120 is configured to collect optical signals at multiple preset positions on the first temperature sensing optical cable at a preset sampling interval, so as to obtain Raman scattering parameters of the optical signals, calculate temperatures corresponding to the Raman scattering parameters of the optical signals at each of the preset positions according to the Raman scattering parameters of the optical signals, and calculate the position of the liquid level of the liquid to be measured based on the temperatures at each of the preset positions.

[0045] In this embodiment, the liquid to be measured can be crude oil, water, chemical solvent, etc. The first temperature sensing optical cable is laid in the liquid to be measured. One end of the first temperature sensing optical cable is communicatively connected to the optical fiber demodulation device, and the other end extends to the bottom of the liquid to be measured, so as to contact the liquid to be measured at different depths, such that the temperatures of the liquid to be measured at different depths affect the optical characteristics of the first temperature sensing optical cable, causing attenuation, phase change, or reflection / scattering of the transmitted optical signals.

[0046] Specifically, when measuring the temperature, the optical fiber demodulation device can generate laser pulses, and the laser is transmitted along the first temperature sensing optical cable. When the laser is transmitted in the optical cable and reaches the liquid to be measured through the part of the optical cable outside the liquid level, due to the difference between the temperature of the external environment and the temperature of the liquid to be measured, photons of the laser interact with molecules in the core of the first temperature sensing optical cable, thereby generating Raman scattering phenomena of different degrees.

[0047] The optical fiber demodulation device obtains multiple optical signals at different positions on the first temperature sensing optical cable at a preset sampling interval. Since the temperatures at different positions on the first temperature sensing optical cable are different, the obtained optical signals also correspond differently. By measuring and analyzing the Raman scattering parameters of these scattered optical signals, such as Raman frequency shift, Stokes frequency, and anti-Stokes frequency, etc., temperature information at different positions along the core can be obtained. Since the propagation speed and time of the laser pulse in the core are measurable, the specific position of the scattering point (i.e., the sensing point) on the core can be calculated according to the propagation speed and time.

[0048] In a distributed temperature measurement sensor, for the optical fiber demodulation device to obtain a temperature data as densely as possible, it can be achieved through multiple aspects such as comprehensive demodulation algorithms, system design, and hardware configuration. For example, in terms of demodulation algorithms, by developing or optimizing demodulation algorithms, the system can resolve temperature data at intervals of every 0.05 m on the temperature sensing optical cable. The sampling frequency of the demodulation device can also be increased to ensure that the system can detect temperature changes more frequently and provide sufficient resolution when needed, so as to obtain more data points in a shorter time. High-precision position resolution can also be used. Such as using optical time domain reflectometry (OTDR) technology or other position resolution methods to accurately determine the position of each temperature data point on the optical cable. This can be achieved by measuring the propagation time of the optical signal in the optical fiber and combining parameters such as the refractive index of the optical fiber to calculate the specific position.

[0049] In one embodiment, the optical fiber demodulation device is used to calculate the change rate of the corresponding temperature between adjacent optical signals; and determine the liquid level height according to the position information corresponding to multiple change rates whose change rates exceed a preset rising threshold and / or falling threshold.

[0050] It can be understood that the temperatures sensed by the temperature-sensitive optical cable during underground laying, in the air outside the storage tank, in the air inside the storage tank, and in the liquid to be measured are all different. When the temperature-sensitive optical cable enters from the air outside the storage tank into the air inside the storage tank, the temperature usually shows a non-smooth turning change. Similarly, when the temperature-sensitive optical cable enters from the air inside the storage tank into the liquid to be measured, the temperature also shows a turning change. The change rates of these temperatures with turning changes are the multiple sub-change rates determined in the above method. By using this objective law, finding the positions with large temperature changes and combining with the actual layout scenario of the temperature-sensing device, the liquid level position can be located.

[0051] In one embodiment, a temperature distribution map is generated according to the temperature information and the corresponding specific positions, which more intuitively helps the user to judge the liquid level position. As Figure 2 shown, it is a temperature distribution map for monitoring the liquid level height in a well. The temperature shows multiple obvious turns in different media. When the first temperature-sensitive optical cable enters the wellhead from the outside air, the first temperature turn occurs. As the well depth increases continuously, the temperature gradually increases. Until the first temperature-sensitive optical cable enters below the well fluid, the temperature shows a discontinuous turning change again. The position of this turning point is the position of the liquid level.

[0052] In one embodiment, the aggregation situation of bubbles in the liquid to be measured is judged by the temperature fluctuation situation in the temperature distribution map.

[0053] In this embodiment, as Figure 4 shown, it is a temperature distribution map obtained by monitoring the temperature inside the crude oil in an oil well. The fluctuating temperature values depict the temperature changes caused by the rising of bubbles in the fluid, and the phenomenon of the aggregation of bubbles growing from small to large is described by the change of the fluctuation amplitude.

[0054] In some chemical productions, such as monitoring the liquid levels in reaction kettles and fermentation tanks, through the liquid level monitoring device of this embodiment, it is possible to simultaneously monitor the liquid level, temperature, and bubbles under the condition of only using one fiber core to measure temperature, so as to determine whether the reaction or fermentation process is proceeding stably, and further achieve the effect of multi-purpose use of one machine.

[0055] In one embodiment, the range of the preset sampling interval is adjustable. When the liquid level monitoring device is only used to measure the temperature of the liquid to be measured, a plurality of optical signals at different positions on the first temperature sensing optical cable are obtained according to the first sampling interval. When the liquid level monitoring device is used to monitor the liquid surface, a plurality of optical signals at different positions on the first temperature sensing optical cable are obtained according to the second sampling interval, and the second sampling interval is smaller than the first sampling interval.

[0056] It can be understood that the smaller the sampling interval is, the more optical signals are collected. When monitoring the liquid surface height, since it is necessary to judge the liquid surface height according to the temperature change turning point, it is necessary to obtain optical signals more densely in order to more accurately find the temperature change turning point and make the calculated liquid surface height more accurate. For example, when measuring the liquid surface in an oil storage tank, the second sampling interval is set to 0.05 m, and the measured liquid surface height accuracy is ±0.05 m, which meets the accuracy requirements of actual liquid surface monitoring. When only measuring the temperature, the first sampling interval is set to 1 m, which makes the temperature measurement faster, reduces the energy consumption of the device, and can also accurately and comprehensively measure the temperature of the oil.

[0057] In one embodiment, the preset sampling interval is less than or equal to 0.05 meters, the number of the first temperature sensing optical cables is one, and the first temperature sensing optical cable is laid perpendicular to the liquid surface of the liquid to be measured.

[0058] In this embodiment, only one first temperature sensing optical cable is laid perpendicular to the liquid surface of the liquid to be measured, and the liquid surface monitoring and temperature monitoring can be realized at the lowest cost. Specifically, when monitoring an oil and gas storage tank, the first temperature sensing optical cable is vertically fixed on the inner wall of the storage tank. One end of the first temperature sensing optical cable extends to the bottom of the storage tank, and the other end passes through the storage tank and is connected to the optical fiber demodulation device.

[0059] In the existing optical cable temperature measurement devices, generally, the optical cable is laid in a ring around the top of the tank, or is laid in a loop from top to bottom along the outside of the storage tank, and then whether there is a fire risk is judged according to the measured temperature data. For the first method of laying the optical cable in a ring around the top of the tank, the change in the liquid surface height cannot be measured; for the second method of laying the optical cable in a loop from top to bottom along the outside of the storage tank, although more temperature data can be obtained, the amount of the optical cable is greatly increased, increasing the detection cost and installation cost. At the same time, due to insufficient spatial resolution of the existing optical fiber temperature measurement devices, it is difficult to accurately capture small leakage points or small-scale ignition points, resulting in inaccurate early warning.

[0060] It is worth mentioning that since the preset sampling interval of the temperature measurement device in this embodiment is less than or equal to 0.05 meters, it is possible to lay the first temperature-sensitive optical cable perpendicular to the liquid level of the liquid to be measured. When the preset sampling interval is large or the temperature-sensitive size of the first temperature-sensitive optical cable is low, it is difficult to obtain enough temperature data only through a single optical cable perpendicular to the liquid level, resulting in the liquid level position corresponding to the temperature turning point in the temperature distribution map being much lower than the actual liquid level position, and the measured liquid level height data being inaccurate. When the optical fiber demodulation device can obtain the corresponding temperature data on the first temperature-sensitive optical cable every at most 0.05 meters, laying the first temperature-sensitive optical cable perpendicular to the liquid level of the liquid to be measured on the inner wall of the storage tank can also obtain enough temperature data, so that the measured liquid level height is closer to the real liquid level height.

[0061] In summary, for the above liquid level monitoring device and monitoring method, the first temperature-sensitive optical cable is installed in the liquid to be measured. Since the temperatures at different depths of the liquid to be measured are different, when the first temperature-sensitive optical cable contacts the liquid to be measured at different depths, its optical characteristics will change, resulting in different degrees of Raman scattering of the transmitted optical signal at different temperatures. These optical signals with different Raman scattering parameters are captured by the optical fiber demodulation device and converted into electrical signals. After the optical fiber demodulation device analyzes and processes the electrical signals, different temperature values are obtained. Then, according to the turning point of the temperature change above and below the liquid level of the liquid to be measured among different temperature values, the position of the liquid level can be determined. For the monitoring device of the present application, measurement is carried out using the first temperature-sensitive optical cable. Since the optical cable is not charged in the liquid to be measured, potential hazards such as the fire risk caused by electrical leakage are avoided. Moreover, the magnetic field itself does not directly change the frequency or intensity of light, so it does not directly affect the Raman scattering process. Therefore, after the first temperature-sensitive optical cable is installed, the Raman scattering parameters of the optical signals collected by the optical fiber demodulation device are less affected by external interference, thereby improving the measurement accuracy of the liquid level. It is worth mentioning that in the present application, the temperature-sensitive optical cable is vertically laid in the liquid to be measured, so that the amount of the temperature-sensitive optical cable used is less and the laying cost is lower.

[0062] In addition, during the process of monitoring the liquid level by the monitoring device of the present application, the temperature of the liquid to be measured is also synchronously monitored in real time, which helps to detect abnormal temperatures in a timely manner and avoid fire risks. That is, the device of the present application realizes the simultaneous monitoring of the liquid level height and temperature with the same optical cable or fiber core in the same measurement, and realizes the detection of liquid level anomalies, leaks and high-temperature risks with a more concise structure and lower cost, and is more practical.

[0063] In one embodiment, the number of the first temperature-sensitive optical cables is multiple, and the multiple first temperature-sensitive optical cables are laid at intervals perpendicular to the liquid level of the liquid to be measured. The optical fiber demodulation device is provided with a plurality of optical cable connection ports, and the second ends of the first temperature-sensitive optical cables are correspondingly connected to the optical cable connection ports.

[0064] In this embodiment, multiple first temperature-sensing optical cables are laid at intervals perpendicular to the liquid surface of the liquid to be measured, jointly monitoring the liquid surface height. On the one hand, it can improve the accuracy of the detected liquid surface height and the accuracy of liquid temperature measurement by obtaining more temperature data. On the other hand, it can also monitor the flatness of the liquid surface.

[0065] Specifically, in this embodiment, the optical fiber demodulation device is provided with 16 optical cable connection channels and is simultaneously connected to 16 first temperature-sensing optical cables to monitor the liquid surface. Each first temperature-sensing optical cable is evenly spaced along the cylindrical inner wall of the storage tank, and the sampling intervals on each first temperature-sensing optical cable are set the same. The optical fiber demodulation device acquires the optical signals on each first temperature-sensing optical cable and analyzes the optical signals to obtain the temperature distribution maps corresponding to each first temperature-sensing optical cable. It detects whether the difference in the heights corresponding to the liquid surface in each temperature distribution map exceeds the difference threshold. When the difference in the heights corresponding to the liquid surface in each temperature distribution map exceeds the difference threshold, it indicates that the flatness of the liquid surface is abnormal. Otherwise, it is considered that the liquid surface flatness is good.

[0066] In industries such as chemistry, petroleum, and pharmaceuticals, the inclination of the liquid surface may lead to safety accidents such as spills and leaks. By monitoring the flatness of the liquid surface, potential risks can be detected in a timely manner, and measures can be taken for intervention to avoid or reduce the occurrence of safety accidents. In industries such as coatings and paints, maintaining the flatness of the liquid surface can ensure the uniformity and consistency of the products. The liquid surface monitoring device of this embodiment can not only measure the liquid surface height more accurately but also monitor the flatness of the liquid surface, further improving the detection ability of liquid leakage risks.

[0067] In one embodiment, a waterproof layer is coated on the first end of the first temperature-sensing optical cable.

[0068] In this embodiment, the first end of the first temperature-sensing optical cable is arranged in the liquid to be measured. When the first end of the first temperature-sensing optical cable is immersed for a long time, the liquid to be measured is likely to enter the protective sleeve outside the fiber core and react with the fiber core, resulting in hydrogen loss of the fiber core.

[0069] Fiber core hydrogen loss refers to the phenomenon that hydrogen molecules in the fiber core react with defects in the fiber core glass, resulting in an increase in the absorption loss of the fiber core. When hydrogen molecules diffuse into the voids of the silica glass network in the fiber core, they will become dissolved infrared-activated molecular hydrogen, thereby triggering absorption loss, intensifying the attenuation of the optical signal in the fiber core, and directly affecting the transmission and reception of temperature information.

[0070] Therefore, in this embodiment, a waterproof layer is provided on the first end of the first temperature-sensitive optical cable to seal the fiber core, prevent water or other hydrogen-containing liquids from entering the optical cable, and avoid hydrogen molecules in external moisture from entering the fiber core, thereby reducing the possibility of reaction with defects in the fiber core glass and reducing the hydrogen loss of the fiber core.

[0071] In one embodiment, a fiber core cutoff ring is provided at the first end of the first temperature-sensitive optical cable.

[0072] In this embodiment, by providing a fiber core cutoff ring at the first end of the first temperature-sensitive optical cable, a clear optical reflection cross-section is formed at the tail end of the first temperature-sensitive optical cable. As Figure 2 shown, there is a vertical cross-section at the very end of the temperature distribution diagram, and this part corresponds to the fiber core cutoff ring part. The optical reflection cross-section provides a clear reflection point, which helps to reduce the scattering and loss of optical signals in the optical cable, thereby maintaining the intensity and stability of the optical signals, improving the signal quality, and enabling the fiber optic demodulation device to more easily detect and identify optical signals.

[0073] In one embodiment, it further includes:

[0074] An alarm device, communicatively connected to the fiber optic demodulation device, which issues an alarm when the change value of the liquid level position exceeds the liquid level change threshold and / or when the temperature value corresponding to the temperature signal exceeds the temperature threshold.

[0075] In this embodiment, the alarm device is communicatively connected to the fiber optic demodulation device. When the temperature value related to the liquid to be measured in the temperature data analyzed by the fiber optic demodulation device exceeds the temperature threshold, it indicates a fire risk, and the alarm device is correspondingly activated; when the change value of the liquid level position data analyzed by the fiber optic demodulation device exceeds the liquid level change threshold, it indicates a leakage risk, and the alarm device is correspondingly activated.

[0076] In one embodiment, it further includes:

[0077] A display device, communicatively connected to the fiber optic demodulation device, which displays the temperature distribution information according to the temperatures at each of the preset positions.

[0078] In this embodiment, the display device is used to display the information of the temperature distribution diagram in real time and can be provided with multiple display modes. For example, it can adopt a real-time curve mode, a scene mode, and a grid mode, and the temperature distribution information can be quickly viewed by selecting different display modes. Through different display modes, users can more intuitively understand the height and temperature information of the liquid to be measured.

[0079] In one embodiment, as Figure 6 shown, the fiber optic demodulation device 710 is further used to demodulate the acoustic vibration signal, and the device further includes:

[0080] The vibrating optical cable 720 is used to transmit the acoustic vibration signals generated by gas leakage and / or liquid leakage of the liquid to be measured. The first end of the vibrating optical cable is communicatively connected to a sound monitoring device 730, and the second end of the vibrating optical cable 730 is communicatively connected to the optical fiber demodulation device 710.

[0081] In this embodiment, the optical fiber demodulation device has the function of demodulating the optical signal transmitted by the first temperature-sensing optical cable into temperature, and also has the function of demodulating the acoustic vibration signal transmitted by the first temperature-sensing optical cable to determine whether there is gas and / or liquid leakage. In vibrating optical fiber sensing, when the optical fiber is subjected to external vibration or strain, the light in the optical fiber will undergo Rayleigh scattering, and the characteristics of the scattered light (such as intensity, phase, etc.) will change with the change of vibration or strain. Therefore, by obtaining the characteristics of the scattered light, it is converted into numbers that can detect and locate the vibration or strain along the optical fiber after being demodulated by the optical fiber demodulation device, so as to realize the real-time monitoring and early warning of vibration or strain.

[0082] As Figure 6 shown, the optical fiber demodulation device 710 has multiple communication channels, and the first temperature-sensing optical cable 740 and the vibrating optical cable 720 are respectively connected to different communication interfaces of the optical fiber demodulation device 710. The vibrating optical cable 720 is connected to a sound monitoring device 730, and the vibrating optical cable is laid above the liquid to be measured so that the sound monitoring device 730 can better capture the acoustic vibration signals generated during gas leakage. The captured acoustic vibration signals are transmitted to the optical fiber demodulation device via the vibrating optical cable 720 for signal processing to determine whether there is gas leakage.

[0083] In practical applications, the vibrating optical cable 720 can be laid in an S shape above the liquid surface to be measured, or can be laid around the outer wall of the storage tank. The specific laying method is determined according to actual needs and is not limited here. Through the device of this embodiment, the functions of liquid level monitoring, gas leakage monitoring, and high-temperature monitoring can be integrated into one, making the application scenario of the device richer, more practical, and the cost controllable.

[0084] In one embodiment, as Figure 7 shown, it further includes:

[0085] A second temperature-sensing optical cable 830, the second temperature-sensing optical cable 830 is communicatively connected to the optical fiber demodulation device 810, and the second temperature-sensing optical cable 830 is laid in a ring shape parallel to the liquid surface above the liquid to be measured.

[0086] When the temperature of the tank body rises, some oil and gas will vaporize with heat to the top of the tank. The accumulation of heat at the top may pose a fire risk. Therefore, when measuring the temperature, the temperature of the top of the storage tank should also be monitored to give an early warning in time to avoid fires and explosions. The installation method is that the temperature sensing optical fiber is passed through a galvanized pipe to the top of the tank, and then fixed to the guardrail on the top of the tank with stainless steel tie straps. This method is to monitor the fires around the top and the tank body of the oil tank, and the temperature will be directly or conducted through the tank body to the temperature sensing optical fiber.

[0087] For example, the leakage of a floating roof storage tank is monitored in real time. A floating roof storage tank is composed of a floating roof floating on the surface of the medium and a vertical cylindrical tank wall. The floating roof rises and falls with the increase or decrease of the storage volume of the medium in the tank. There is an annular sealing device between the outer edge of the floating roof and the tank wall. The medium in the tank is always directly covered by the inner floating roof, reducing the volatilization of the medium. The second temperature sensing optical cable is looped near the sealing device. When the stored oil in the tank overflows, heat exchange will occur when the overflowing stored oil flows through the second temperature sensing optical cable, causing the temperature of the second temperature sensing optical cable to change greatly in a short time, achieving the effect of accurately and quickly detecting abnormalities.

[0088] In this embodiment, as Figure 7 shown, the second temperature sensing optical cable 830 and the first temperature sensing optical cable 820 are respectively connected to two channels of the optical fiber demodulation device 810. Through the second temperature sensing optical cable 830, the requirements for safety monitoring can be met, and through the first temperature sensing optical cable 810, the requirements for daily operation monitoring can be satisfied.

[0089] In one embodiment, it further includes:

[0090] A remote control terminal, communicatively connected to the optical fiber demodulation device, the remote control terminal is loaded with preset control software, and the remote control terminal is used to remotely obtain the temperature at each of the preset positions according to the preset control software.

[0091] In this embodiment, the remote control terminal can obtain the temperature data of the monitored positions of the optical fiber demodulation device in real time and continuously, so that the user can access and manage the optical fiber demodulation device through the remote control terminal at any location without having to go to the site in person. This flexibility greatly improves work efficiency and reduces operation and maintenance costs.

[0092] Embodiment 2

[0093] In this embodiment, as Figure 3 shown, a liquid level monitoring method is provided, including:

[0094] Step 410, collecting optical signals at multiple preset positions on a target first temperature sensing optical cable at a preset sampling interval, the target first temperature sensing optical cable is laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured, and at least part of the first temperature sensing optical cable is exposed outside the liquid surface of the liquid to be measured;

[0095] In this embodiment, the liquid to be measured can be crude oil, water, chemical solvents, etc. The first temperature-sensitive optical cable is laid in the liquid to be measured. One end of the first temperature-sensitive optical cable is communicatively connected to the optical fiber demodulation device, and the other end extends to the bottom of the liquid to be measured, so as to contact the liquid to be measured at different depths, such that the temperatures of the liquid to be measured at different depths affect the optical properties of the first temperature-sensitive optical cable, resulting in attenuation, phase change, or reflection / scattering of the transmitted optical signal.

[0096] When measuring the temperature, the optical fiber demodulation device can generate laser pulses, and the laser is transmitted along the first temperature-sensitive optical cable. When the laser gradually reaches the liquid to be measured from the external environment, due to the difference between the temperature of the external environment and the temperature of the liquid to be measured, the photons of the laser interact with the molecules in the core of the first temperature-sensitive optical cable, thereby generating different degrees of scattering phenomena.

[0097] In one embodiment, the preset sampling interval is less than or equal to 0.05 meters, so as to obtain denser optical signals, obtain more comprehensive and denser temperature data, and thus make the liquid level monitoring result more reliable.

[0098] Step 420: Preprocess the multiple optical signals to obtain the Raman scattering parameters of the optical signals, and calculate the temperatures corresponding to the Raman scattering parameters of the optical signals at each of the preset positions according to the Raman scattering parameters of the optical signals;

[0099] The optical fiber demodulation device obtains multiple optical signals at different positions on the first temperature-sensitive optical cable according to the preset sampling interval. Since the temperatures at different positions on the first temperature-sensitive optical cable are different, the obtained optical signals also correspond differently. By measuring and analyzing the characteristics of these scattered optical signals, such as Raman frequency shift, Stokes frequency, and anti-Stokes frequency, etc., the optical signals at different positions along the core are converted into temperature signals.

[0100] The optical fiber demodulation device further analyzes the temperature signal and converts the temperature signal into a temperature value. The signal processing process includes filtering, amplification, and signal calibration and compensation, etc. Since the propagation speed and time of the laser pulse in the core are measurable, the specific position of the scattering point (i.e., the sensing point) on the core can be calculated according to the propagation speed and time, thereby obtaining the mapping relationship between different positions on the first temperature-sensitive optical cable and the corresponding temperature values.

[0101] Step 430: Calculate the position of the liquid level of the liquid to be measured based on the temperatures at each of the preset positions.

[0102] In one embodiment, the step of calculating the position of the liquid level of the liquid to be measured based on the temperatures at each of the preset positions includes:

[0103] Step 431, calculate the change rate of the corresponding temperature at adjacent preset positions;

[0104] Step 432, determine the liquid level height according to the position information corresponding to multiple change rates whose change rates exceed the preset rising threshold and / or falling threshold.

[0105] It can be understood that the temperatures sensed by the temperature-sensitive optical cable during underground laying, in the air outside the storage tank, in the air inside the storage tank, and in the liquid to be measured are all different. When the temperature-sensitive optical cable enters from the air outside the storage tank into the air inside the storage tank, the temperature usually shows a non-smooth turning change. Similarly, when the temperature-sensitive optical cable enters from the air inside the storage tank into the liquid to be measured, the temperature also shows a turning change. The change rates of these temperatures with turning changes are the multiple sub-change rates determined in the above method. Using this objective law, find the positions with large temperature changes, and combine the actual layout scenario of the temperature-sensing device to locate the liquid level position.

[0106] In one embodiment, a temperature distribution map is generated according to the temperature information and the corresponding specific positions, which can more intuitively help the user judge the position of the liquid level. As Figure 2 shown, it is a temperature distribution map for monitoring the liquid level height in a well. The temperature shows multiple obvious turns in different media. When the first temperature-sensitive optical cable enters the wellhead from the outside air, the first temperature turn occurs. As the well depth increases continuously, the temperature gradually increases. Until the first temperature-sensitive optical cable enters below the well fluid, the temperature shows a discontinuous turning change again, and the position of this turning point is the position of the liquid level.

[0107] In one embodiment, the bubble aggregation situation in the liquid to be measured is judged by the temperature fluctuation situation in the temperature distribution map.

[0108] In this embodiment, as Figure 4 shown, it is the temperature monitoring situation inside the crude oil in an oil well. The fluctuating temperature values depict the temperature change caused by the bubbles rising in the fluid, and the change of the fluctuation amplitude describes the phenomenon of the bubble aggregation from small to large.

[0109] In some chemical production processes, such as monitoring the liquid level in a reaction kettle or a fermentation tank, by this method, while monitoring the liquid level and temperature, bubble detection can also be carried out to ensure the stable progress of the reaction or fermentation process.

[0110] In one embodiment, after the step of calculating the position of the liquid level of the liquid to be measured based on the temperatures at the respective preset positions, the following further includes:

[0111] Detect whether the change value of the liquid level position within a preset time period is greater than or equal to the liquid level change threshold. When the change value of the liquid level position is greater than the liquid level change threshold, a first alarm is issued;

[0112] and / or

[0113] Detect whether the temperature value is greater than the temperature threshold; when the temperature value is greater than the temperature threshold, a second alarm is issued.

[0114] In this embodiment, the alarm device is communicatively connected to the optical fiber demodulation device. When the temperature value related to the liquid to be measured in the temperature data analyzed by the optical fiber demodulation device exceeds the temperature threshold, it indicates a fire risk, and the alarm device is correspondingly activated; when the change value of the liquid level position data analyzed by the optical fiber demodulation device exceeds the liquid level change threshold, it indicates a leakage risk, and the alarm device is correspondingly activated. The preset time period can be set to one day, one week, or one month, and is specifically set according to the actual monitoring requirements, and is not limited here specifically.

[0115] It should be understood that although Figure 3 the steps in the flowchart of Figure 3 are shown in sequence according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear description in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover,

[0116] Embodiment III

[0117] In this embodiment, as Figure 5 shown, a liquid level monitoring device is provided, including:

[0118] The first temperature sensing optical cable 610 is used to be laid in the liquid to be measured and perpendicular to the liquid level of the liquid to be measured. At least a part of the first temperature sensing optical cable is exposed outside the liquid level of the liquid to be measured. Among them, the first end of the first temperature sensing optical cable is located below the liquid level of the liquid to be measured, and the second end of the first temperature sensing optical cable is connected to the optical fiber demodulation device;

[0119] Measurement host 620, the measurement host includes an optical fiber demodulation device 621 and a display 622, wherein the optical fiber demodulation device is used to collect optical signals at multiple preset positions on the first temperature-sensitive optical cable at a preset sampling interval to obtain Raman scattering parameters of the optical signals, calculate temperatures corresponding to the Raman scattering parameters of the optical signals at each of the preset positions according to the Raman scattering parameters of the optical signals, and calculate the position of the liquid level of the liquid to be measured based on the temperatures at each of the preset positions; the display is used to communicate with the optical fiber demodulation device to display the temperature distribution map;

[0120] User terminal 630, which is used to communicate with the measurement host. The user terminal is loaded with user terminal software, and the control and data calling of the measurement host are realized through the user terminal software.

[0121] The measurement host in this embodiment has multiple external interfaces, can communicate with a local server and a third-party platform, and can transmit the temperature values corresponding to any position at the preset sampling interval externally to reproduce the on-site information at a remote control center, which is of great help for realizing an unmanned control room.

[0122] In the liquid level monitoring of each storage tank position of large storage tanks, the liquid level monitoring devices corresponding to each storage tank can operate independently, and at the same time, the output signals are summarized to the general dispatching room for centralized management by the general dispatcher. According to the on-site needs, the data of each device is displayed in real time, and at the same time, it is transmitted to the monitor (i.e., the user terminal) in the master control room to perform intelligent analysis on the fault trend of the monitored object, accurately locate the fault point, guide the maintenance work, and provide an effective guarantee for the safe operation of the storage tank system.

[0123] Specifically, for the liquid level monitoring of four storage tanks, four first temperature-sensitive optical cables are vertically laid on the inner wall of each storage tank, and the four first temperature-sensitive optical cables are evenly distributed along the inner wall of the storage tank. The sixteen first temperature-sensitive optical cables are jointly connected to the measurement host, and the preset sampling interval of the optical fiber demodulation device is 0.05 m. A first optical cable surplus section is arranged at the starting end of the first temperature-sensitive optical cable, a second optical cable surplus section is arranged at the tail end, and an isolation device is arranged at the tail end to achieve waterproofing at the tail end. In addition, a third surplus section is arranged every 200 meters on each first temperature-sensitive optical cable to further ensure that the optical fiber is not broken during the laying process and improve the transmission efficiency of the optical signal.

[0124] The liquid level monitoring data of the four storage tanks are analyzed by the optical fiber demodulation device to generate corresponding temperature distribution maps, and each temperature distribution map is independently displayed on the measurement host. Through the temperature distribution map, the user monitors the liquid level height, the liquid storage temperature, and the simultaneous situation of internal bubbles in the liquid storage to detect safety risks such as fires and leaks in a timely manner.

[0125] In one embodiment, the measurement host communicates with the fire alarm and can also interact with the third-party platform to actively transmit alarms or partition temperatures externally in a timely manner to remind of risks.

[0126] Those of ordinary skill in the art can understand that all or part of the processes of implementing the methods in the above embodiments can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in many forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0127] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0128] The above-described embodiments merely represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A liquid level monitoring device, characterized in that: Including the first temperature-sensitive optical cable and optical fiber demodulation equipment, The first temperature-sensing optical cable is used to be laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured. The first temperature-sensing optical cable is at least partially exposed above the liquid surface of the liquid to be measured. The first end of the first temperature-sensing optical cable is located below the liquid surface of the liquid to be measured, and the second end of the first temperature-sensing optical cable is connected to the optical fiber demodulation device. The optical fiber demodulation device is used to collect optical signals at a plurality of preset positions on the first temperature-sensitive optical cable at a preset sampling interval to obtain Raman scattering parameters of the optical signals, calculate the temperature corresponding to the Raman scattering parameters of the optical signals at each of the preset positions based on the Raman scattering parameters of the optical signals, and calculate the position of the liquid level of the liquid to be measured based on the temperature at each of the preset positions; The range of the preset sampling interval is adjustable. When the liquid level monitoring device is used only to measure the temperature of the liquid to be measured, multiple optical signals at different positions on the first temperature-sensitive optical cable are obtained according to the first sampling interval. When the liquid level monitoring device is used to monitor the liquid level, multiple optical signals at different positions on the first temperature-sensitive optical cable are obtained according to the second sampling interval. The second sampling interval is smaller than the first sampling interval and is less than or equal to 0.05 meters. The liquid level monitoring device is also used to determine the bubble aggregation situation in the liquid to be tested based on the temperature fluctuation situation; The liquid level monitoring device also includes: A second temperature-sensitive optical cable is communicatively connected to the optical fiber demodulation device. The second temperature-sensitive optical cable is laid in a ring above the liquid to be measured parallel to the liquid surface. The second temperature-sensitive optical cable is arranged in a ring on the sealing device of the floating roof storage tank. When the oil stored in the tank leaks, the overflowing liquid undergoes heat exchange when flowing through the second temperature-sensitive optical cable, causing the temperature of the second temperature-sensitive optical cable to change significantly in a short period of time, thereby detecting top leakage.

2. The device according to claim 1, characterized in that, There are multiple first temperature-sensitive optical cables, and the multiple first temperature-sensitive optical cables are laid perpendicularly to the liquid surface of the liquid to be measured and spaced apart. The optical fiber demodulation device is provided with multiple optical cable connection ports, and the second end of each first temperature-sensitive optical cable is correspondingly connected to each optical cable connection port.

3. The device according to claim 1, characterized in that, The first end of the first temperature-sensitive optical cable is covered with a waterproof layer.

4. The device according to claim 1, characterized in that, A core cut-off ring is provided at the first end of the first temperature-sensitive optical cable.

5. The device according to claim 1, characterized in that, Also includes: An alarm device is communicatively connected to the optical fiber demodulation device, and issues an alarm when the change value of the liquid level position exceeds a liquid level change threshold, and / or when the temperature value corresponding to the temperature signal exceeds a temperature threshold.

6. The device according to claim 1, characterized in that, Also includes: A display device is communicatively connected to the optical fiber demodulation device and displays temperature distribution information according to the temperature of each preset position.

7. The device according to claim 1, characterized in that, The optical fiber demodulation device is also used to demodulate the acoustic vibration signal, and the device also includes: The vibration optical cable is used to transmit the acoustic vibration signal generated by the gas leakage and / or liquid leakage of the liquid to be tested. The first end of the vibration optical cable is communicatively connected to the sound monitoring device, and the second end of the vibration optical cable is communicatively connected to the optical fiber demodulation equipment.

8. The device according to any one of claims 1 to 7, characterized in that: Also includes: A remote control terminal, which is communicatively connected to the optical fiber demodulation device. The remote control terminal is loaded with preset control software and is used to remotely obtain the temperatures at each of the preset positions according to the preset control software.

9. A liquid level monitoring method, applied to the liquid level monitoring device according to any one of claims 1 to 8, characterized in that: It includes: Collecting optical signals at multiple preset positions on a target first temperature sensing optical cable at a preset sampling interval. The target first temperature sensing optical cable is laid in the liquid to be measured and is perpendicular to the liquid level of the liquid to be measured. At least a part of the first temperature sensing optical cable is exposed above the liquid level of the liquid to be measured; Preprocessing the multiple optical signals to obtain Raman scattering parameters of the optical signals, and calculating the temperatures corresponding to the Raman scattering parameters of the optical signals at each of the preset positions according to the Raman scattering parameters of the optical signals; Calculating the position of the liquid level of the liquid to be measured based on the temperatures at each of the preset positions; Wherein, the range of the preset sampling interval is adjustable. When the liquid level monitoring device is only used to measure the temperature of the liquid to be measured, multiple optical signals at different positions on the first temperature sensing optical cable are obtained at a first sampling interval. When the liquid level monitoring device is used to monitor the liquid level, multiple optical signals at different positions on the first temperature sensing optical cable are obtained at a second sampling interval. The second sampling interval is smaller than the first sampling interval, and the second sampling interval is less than or equal to 0.05 meters; The liquid level monitoring device further includes: A second temperature sensing optical cable, which is communicatively connected to the optical fiber demodulation device. The second temperature sensing optical cable is laid in a ring parallel to the liquid level above the liquid to be measured. Among them, the second temperature sensing optical cable is looped on the sealing device of the floating roof storage tank. When the stored oil in the tank leaks, heat exchange will occur when the overflowing liquid flows through the second temperature sensing optical cable, causing a large change in the temperature of the second temperature sensing optical cable in a short time to detect the top leakage; The liquid level monitoring device is further used to generate a temperature distribution map based on the temperature information and the corresponding specific positions, and judge the bubble aggregation situation in the liquid to be measured through the temperature fluctuation situation in the temperature distribution map.

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