CN118687654A - Liquid level monitoring device and monitoring method - Google Patents

Abstract

The present invention provides a liquid level monitoring device and a monitoring method, the device comprising: a first temperature-sensitive optical cable at least partially exposed to the liquid surface of the liquid to be measured, which is used to be laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured, wherein the first end of the first temperature-sensitive optical cable is located below the liquid surface of the liquid to be measured, and the second end of the first temperature-sensitive optical cable is connected to an optical fiber demodulation device; the optical fiber demodulation device is used to collect optical signals at multiple preset positions on the first temperature-sensitive optical cable according to a preset sampling interval to obtain Raman scattering parameters of the optical signal, calculate the corresponding temperature according to the Raman scattering parameters of the optical signal, and calculate the position of the liquid surface of the liquid to be measured based on the temperature of each preset position. The monitoring device of the present application uses the first temperature-sensitive optical cable for measurement. Since the optical cable is not charged in the liquid to be measured, it avoids hidden dangers such as fire risks caused by power leakage; at the same time, the optical cable can be less interfered by the surrounding electromagnetic field, and the measurement result is more accurate.

Description

Liquid level monitoring device and monitoring method

Technical Field

The present invention relates to the technical field of storage tank monitoring, and in particular to a liquid level monitoring device and a monitoring method.

Background Art

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

Existing tank level monitoring can be roughly divided into three types: magnetostrictive level meter, radar level meter and servo level meter. All three types of level monitoring are charged point measurement, which inevitably brings certain safety hazards. For example, during the charged measurement process, static electricity may be generated due to electrical contact, separation, friction and other factors. The static charge accumulates to a certain extent and is suddenly released, which may generate static sparks. In the flammable and explosive environment of oil tanks, static sparks can easily ignite the oil and gas mixture, causing 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 of the oil tank, which in turn affects the safe management and operation of the oil tank.

Therefore, there is a need for a liquid level monitoring device with better safety and stronger anti-interference ability.

Summary of the invention

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

A liquid level monitoring device, comprising:

A first temperature-sensitive optical cable, which is used to be laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured, wherein the first temperature-sensitive optical cable is at least partially exposed to the liquid surface of the liquid to be measured, wherein the first end of the first temperature-sensitive optical cable is located below the liquid surface 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;

The optical fiber demodulation device is used to collect optical signals at multiple preset positions on the first temperature-sensitive optical cable according to 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 preset position according to the Raman scattering parameters of the optical signals, and obtain the position of the liquid level of the liquid to be measured based on the temperature calculation of each preset position.

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

In one embodiment, 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 of the first temperature-sensitive optical cables is correspondingly connected to each of the optical cable connection ports.

In one embodiment, the first end of the first temperature-sensitive optical cable is coated with a waterproof layer.

In one embodiment, a core cut-off ring is disposed at the first end of the first temperature-sensitive optical cable.

In one embodiment, it further includes:

An alarm device is used to communicate with the optical fiber demodulation device and issue 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.

In one embodiment, it further includes:

The display device is used to communicate with the optical fiber demodulation device and display temperature distribution information according to the temperature of each preset position.

In one embodiment, the optical fiber demodulation device is also used to demodulate the acoustic vibration signal, and the device further comprises:

The vibration optical cable is used to transmit the sound wave 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.

In one embodiment, it further includes:

A second temperature-sensitive optical cable is communicatively connected to the optical fiber demodulation device, and the second temperature-sensitive optical cable is laid in a ring above the liquid to be measured parallel to the liquid surface.

In one embodiment, it further includes:

A remote control terminal is used for communicating with the optical fiber demodulation device. The remote control terminal is loaded with preset control software. The remote control terminal is used for remotely acquiring the temperature of each preset position according to the preset control software.

A liquid level monitoring method, comprising:

Collecting optical signals at a plurality of preset positions on a target first temperature-sensitive optical cable according to a preset sampling interval, wherein the target first temperature-sensitive optical cable is laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured, and the first temperature-sensitive optical cable is at least partially exposed to the liquid surface of the liquid to be measured;

Preprocessing the plurality of optical signals to obtain Raman scattering parameters of the optical signals, and calculating the temperature 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;

The position of the liquid level of the liquid to be measured is calculated based on the temperature of each of the preset positions.

In one embodiment, after the step of calculating the position of the liquid level of the liquid to be measured based on the temperature of each of the preset positions, the method further includes:

Detecting 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 issuing a first alarm when the change value of the liquid level position is greater than the liquid level change threshold;

and/or

Detecting whether the temperature value is greater than a temperature threshold; and issuing a second alarm when the temperature value is greater than the temperature threshold.

The above-mentioned liquid level monitoring device and monitoring method install the first temperature-sensitive optical cable in the liquid to be measured. Since the temperature at different depths of the liquid to be measured is 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 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. After that, the position of the liquid level can be determined according to the turning point of the temperature change above and below the liquid surface of the liquid to be measured in different temperature values. The monitoring device of the present application uses the first temperature-sensitive optical cable for measurement. Since the optical cable is not charged in the liquid to be measured, the hidden dangers such as the risk of fire caused by power leakage are avoided, and the magnetic field itself will not directly change the frequency or intensity of the light, so it will not directly affect the Raman scattering process. Therefore, after the first temperature-sensitive optical cable is installed, the Raman scattering parameters of the optical signal collected by the optical fiber demodulation device are less subject to 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 less temperature-sensitive optical cable is used and the laying cost is lower.

In addition, the monitoring device of the present application also simultaneously detects the temperature of the liquid to be tested during the process of monitoring the liquid level, which helps to detect abnormal temperature in a timely manner and avoid fire risks. That is, the device of the present application uses the same optical cable or fiber core to simultaneously realize liquid level height monitoring and temperature monitoring in the same measurement, thereby achieving a more streamlined structure and lower cost, and detecting liquid level abnormalities, leakage and high temperature risks at the same time, which is more practical.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of an application scenario of a liquid level monitoring device in one embodiment;

FIG2 is a schematic diagram of a temperature distribution diagram in one embodiment;

FIG3 is a schematic flow chart of a liquid level monitoring method in one embodiment;

FIG4 is a schematic diagram of bubble aggregation characteristics in a temperature distribution diagram in one embodiment;

FIG5 is a schematic diagram of another liquid level monitoring device in one embodiment;

FIG6 is a schematic diagram of the assembly relationship between the vibration optical cable and the optical fiber demodulation device in one embodiment;

FIG. 7 is a schematic diagram of the assembly relationship between the second temperature-sensitive optical cable and the optical fiber demodulation device in one embodiment.

DETAILED DESCRIPTION

In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with 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.

Embodiment 1

In this embodiment, as shown in FIG1 , a liquid level monitoring device is provided, which includes a first temperature sensing optical cable 110 and an optical fiber demodulation device 120, wherein:

A first temperature-sensitive optical cable 110, which is used to be laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured, wherein the first temperature-sensitive optical cable is at least partially exposed to the liquid surface of the liquid to be measured, wherein the first end of the first temperature-sensitive optical cable is located below the liquid surface 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;

The optical fiber demodulation device 120 is used to collect optical signals at multiple preset positions on the first temperature-sensitive optical cable according to 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 preset position according to the Raman scattering parameters of the optical signals, and obtain the position of the liquid level of the liquid to be measured based on the temperature calculation at each preset position.

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 connected to the optical fiber demodulation device for communication, and the other end penetrates into the bottom of the liquid to be measured, thereby contacting the liquid to be measured at different depths, so that the temperature of the liquid to be measured at different depths affects the optical properties of the first temperature-sensitive optical cable, causing the transmitted optical signal to be attenuated, phase-changed, or reflected/scattered.

Specifically, when measuring temperature, the optical fiber demodulation device may generate laser pulses, and the laser is transmitted along the first temperature-sensitive optical cable. When the laser is transmitted in the optical cable and transmitted to the liquid to be measured through the portion of the optical cable located outside the liquid surface, 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 fiber core inside the first temperature-sensitive optical cable, thereby generating Raman scattering phenomena of varying degrees.

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 optical signals obtained are also different. By measuring and analyzing the Raman scattering parameters of these scattered optical signals, such as Raman frequency shift, Stokes frequency and anti-Stokes frequency, the temperature information at different positions along the fiber core can be obtained. Since the propagation speed and time of the laser pulse in the fiber core are measurable, the specific position of the scattering point (i.e., the sensing point) on the fiber core can be calculated based on the propagation speed and time.

In distributed temperature sensors, the fiber demodulation device needs to obtain temperature data as densely as possible, which can be achieved through comprehensive demodulation algorithms, system design, hardware configuration and other aspects. For example, in terms of demodulation algorithms, by developing or optimizing demodulation algorithms, the system can parse out the temperature data at every 0.05m interval on the temperature-sensing optical cable. It is also possible to increase the sampling frequency of the demodulation device to ensure that the system can detect temperature changes more frequently and provide sufficient resolution when necessary to obtain more data points in a shorter time. High-precision position resolution can also be used. For example, 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 time it takes for the optical signal to propagate in the optical fiber, and combining parameters such as the refractive index of the optical fiber to calculate the specific position.

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

It is understandable that the temperature sensed by the temperature-sensing optical cable when it is laid underground, the temperature sensed in the air outside the tank, the temperature sensed in the air inside the tank, and the temperature sensed in the liquid to be tested are all different. When the temperature-sensing optical cable enters the air inside the tank from the air outside the tank, the temperature usually changes in a non-smooth transition. Similarly, when the temperature-sensing optical cable enters the liquid to be tested from the air inside the tank, the temperature also changes in a transition. The change rates of these transitional temperatures are the multiple sub-change rates determined in the above method. Using this objective law, we can find the location where the temperature changes greatly, and combine it with the actual layout of the temperature sensing device to locate the liquid level.

In one embodiment, a temperature distribution diagram is generated based on the temperature information and the corresponding specific position, so as to help the user determine the position of the liquid level more intuitively. As shown in Figure 2, it is a temperature distribution diagram for monitoring the liquid level in a well. The temperature has multiple obvious turning points in different media. The first temperature-sensitive optical cable has the first temperature turning point at the point where the air enters the wellhead. As the well depth increases, the temperature gradually increases until the first temperature-sensitive optical cable enters the well fluid. The temperature again shows a discontinuous turning point. The position of this turning point is the position of the liquid level.

In one embodiment, the bubble aggregation in the liquid to be tested is determined by the temperature fluctuation in the temperature distribution diagram.

In this embodiment, as shown in FIG. 4 , a temperature distribution diagram is obtained by monitoring the temperature inside the crude oil in an oil well, wherein the fluctuating temperature values depict the temperature change caused by the bubbles rising in the fluid, and the phenomenon of the bubbles agglomerating from small to large is described through the change in the fluctuation amplitude.

In some chemical production processes, such as monitoring the liquid level in a reactor or fermentation tank, the liquid level monitoring device of this embodiment can simultaneously monitor the liquid level, temperature, and bubbles using only one fiber core to measure the temperature, thereby determining whether the reaction or fermentation process is proceeding stably, further achieving a one-machine-multiple-purposes effect.

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, 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.

It can be understood that the smaller the sampling interval, the more light signals are collected. When monitoring the liquid level, since the liquid level needs to be judged based on the turning point of temperature change, it is necessary to obtain light signals more densely to more accurately find the turning point of temperature change, so that the calculated liquid level is more accurate. For example, when measuring the liquid level in an oil storage tank, the second sampling interval is set to 0.05m, and the measured liquid level accuracy is ±0.05m, which meets the accuracy requirements of actual liquid level monitoring. When only measuring the temperature, the first sampling interval is set to 1m, which makes the temperature measurement faster and reduces the energy consumption of the device, while also accurately and comprehensively measuring the temperature of the oil.

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

In this embodiment, only one first temperature-sensitive optical cable is laid perpendicular to the liquid surface of the liquid to be measured, so that liquid surface monitoring and temperature monitoring can be achieved at the lowest cost. Specifically, when monitoring an oil and gas storage tank, the first temperature-sensitive optical cable is vertically fixed to the inner wall of the storage tank, one end of the first temperature-sensitive 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.

The optical cable temperature measuring devices in the prior art generally lay the optical cable in a circle around the top of the tank, or lay it in a circle from top to bottom along the outside of the tank, and then judge whether there is a fire risk based on the measured temperature data. The first method of laying the optical cable in a circle around the top of the tank cannot measure the change in liquid level; the second method of laying the optical cable in a circle from top to bottom along the outside of the tank can obtain more temperature data, but it greatly increases the amount of optical cable used, and increases the detection cost and installation cost. At the same time, due to the insufficient spatial resolution of the existing optical fiber temperature measuring devices, it is difficult to accurately capture small leakage points or small-scale fire points, resulting in inaccurate early warnings.

It is worth mentioning that, since the preset sampling interval of the temperature measuring device of 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 surface of the liquid to be measured. When the preset sampling interval is large or the temperature-sensing size of the first temperature-sensitive optical cable is low, it is difficult to obtain enough temperature data through only one optical cable perpendicular to the liquid surface, so that the liquid surface position corresponding to the temperature turning point in the temperature distribution diagram is much lower than the actual liquid surface position, resulting in inaccurate measured liquid surface height data. When the optical fiber demodulation device can obtain the corresponding temperature data on the first temperature-sensitive optical cable every 0.05 meters at most, the first temperature-sensitive optical cable is laid perpendicular to the liquid surface of the liquid to be measured on the inner wall of the storage tank, and enough temperature data can also be obtained, so that the measured liquid surface height is closer to the actual liquid surface height.

In summary, the above-mentioned liquid level monitoring device and monitoring method install the first temperature-sensitive optical cable in the liquid to be measured. Since the temperature at different depths of the liquid to be measured is 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 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. After that, the position of the liquid level can be determined according to the turning point of the temperature change above and below the liquid surface of the liquid to be measured in different temperature values. The monitoring device of the present application uses the first temperature-sensitive optical cable for measurement. Since the optical cable is not charged in the liquid to be measured, the hidden dangers such as the risk of fire caused by electricity leakage are avoided, and the magnetic field itself does not directly change the frequency or intensity of the light, so it will not directly affect the Raman scattering process. Therefore, after the first temperature-sensitive optical cable is installed, the Raman scattering parameters of the optical signal collected by the optical fiber demodulation device are less disturbed by the outside world, 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 less temperature-sensitive optical cable is used and the laying cost is lower.

In addition, the monitoring device of the present application also simultaneously monitors the temperature of the liquid to be measured in real time during the process of monitoring the liquid level, which helps to detect abnormal temperature in time and avoid fire risks. That is, the device of the present application uses the same optical cable or fiber core to simultaneously realize liquid level height monitoring and temperature monitoring in the same measurement, achieving a more streamlined structure and lower cost, and detecting liquid level abnormalities, leakage and high temperature risks at the same time, which is more practical.

In one embodiment, 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 of the first temperature-sensitive optical cables is correspondingly connected to each of the optical cable connection ports.

In this embodiment, multiple first temperature-sensitive optical cables are laid perpendicularly to the liquid surface of the liquid to be measured and the liquid level is monitored together. On the one hand, the accuracy of the detected liquid level and the accuracy of the liquid temperature measurement can be improved by obtaining more temperature data. On the other hand, the flatness of the liquid surface can also be monitored.

Specifically, in this embodiment, the optical fiber demodulation device is provided with 16 optical cable connection channels, and 16 first temperature-sensitive optical cables are connected at the same time to monitor the liquid level. Each first temperature-sensitive optical cable is evenly spaced along the cylindrical inner wall of the storage tank, and the sampling intervals on each first temperature-sensitive optical cable are set the same. The optical fiber demodulation device obtains the optical signal on each first temperature-sensitive optical cable, and analyzes the optical signal to obtain the temperature distribution map corresponding to each first temperature-sensitive optical cable. It is detected whether the difference in the height corresponding to the liquid surface in each temperature distribution map exceeds the difference threshold. When the difference in the height 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 flatness of the liquid surface is good.

In the chemical, petroleum, and pharmaceutical industries, the tilt of the liquid surface may lead to safety accidents such as overflow and leakage. By monitoring the flatness of the liquid surface, potential risks can be discovered in a timely manner, and measures can be taken to intervene, thereby avoiding or reducing the occurrence of safety accidents. In the coating and paint industries, keeping the liquid surface flat can ensure the uniformity and consistency of the product. The liquid level monitoring device of this embodiment can not only measure the liquid level more accurately, but also monitor the flatness of the liquid surface, further improving the ability to detect liquid leakage risks.

In one embodiment, the first end of the first temperature-sensitive optical cable is coated with a waterproof layer.

In this embodiment, the first end of the first temperature-sensitive optical cable is disposed in the liquid to be tested. When the first end of the first temperature-sensitive optical cable is immersed for a long time, the liquid to be tested easily enters the protective sheath of the outer layer of the fiber core, reacts chemically with the fiber core, and causes hydrogen loss of the fiber core.

Core hydrogen loss refers to the phenomenon that hydrogen molecules in the core react with defects in the core glass, resulting in increased absorption loss in the core. When hydrogen molecules diffuse into the gaps in the silica glass network in the core, they become soluble infrared-activated molecular hydrogen, which triggers absorption loss, aggravates the attenuation of the optical signal in the core, and directly affects the transmission and reception of temperature information.

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 prevent hydrogen molecules in external moisture from entering the fiber core, thereby reducing the possibility of reaction with defects in the core glass and reducing hydrogen loss in the fiber core.

In one embodiment, a core cut-off ring is disposed at the first end of the first temperature-sensitive optical cable.

In this embodiment, by setting a core cut-off ring at the first end of the first temperature-sensitive optical cable, a clear light reflection cross section is provided at the tail end of the first temperature-sensitive optical cable. As shown in FIG2 , there is a vertical cross section at the very end of the temperature distribution diagram, and this part corresponds to the core cut-off ring part. The light reflection cross section provides a clear reflection point, which helps to reduce the scattering and loss of the optical signal in the optical cable, thereby maintaining the intensity and stability of the optical signal, improving the signal quality, and making it easier for the optical fiber demodulation device to detect and identify the optical signal.

In one embodiment, it further 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 issues an alarm when the temperature value corresponding to the temperature signal exceeds a temperature threshold.

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 tested in the temperature data analyzed by the optical fiber demodulation device exceeds the temperature threshold, it indicates that there is a fire risk, and the alarm device is activated accordingly; 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 that there is a leakage risk, and the alarm device is activated accordingly.

In one embodiment, it further includes:

The display device is connected to the optical fiber demodulation device for displaying temperature distribution information according to the temperature of each preset position.

In this embodiment, the display device is used to display the information of the temperature distribution diagram in real time, and multiple display modes can be set. For example, the real-time curve mode, the scene mode and the grid mode can be used to quickly view the temperature distribution information by selecting different display modes. Through different display modes, the user can more intuitively understand the height and temperature information of the liquid level to be measured.

In one embodiment, as shown in FIG6 , the optical fiber demodulation device 710 is also used to demodulate the acoustic vibration signal, and the device further includes:

The vibration optical cable 720 is used to transmit the sound wave 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 730, and the second end of the vibration optical cable 730 is communicatively connected to the optical fiber demodulation device 710.

In this embodiment, the optical fiber demodulation device has the function of demodulating the optical signal transmitted by the first temperature-sensitive optical cable into temperature, and also has the function of demodulating the acoustic vibration signal transmitted by the first temperature-sensitive optical cable to determine whether there is a gas and/or liquid leak. In vibration 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, the optical fiber demodulation device demodulates it and converts it into a number that can detect and locate the vibration or strain along the optical fiber, so as to realize real-time monitoring and early warning of vibration or strain.

As shown in FIG6 , the optical fiber demodulation device 710 has multiple communication channels, and the first temperature-sensitive optical cable 740 and the vibration optical cable 720 are respectively connected to different communication interfaces of the optical fiber demodulation device 710. The vibration optical cable 720 is connected to a sound monitoring device 730, and the vibration optical cable is laid above the liquid to be tested so that the sound monitoring device 730 can better capture the acoustic vibration signal generated when the gas leaks. The captured acoustic vibration signal is transmitted to the optical fiber demodulation device via the vibration optical cable 720 for signal processing to determine whether there is a gas leak.

In practical applications, the vibration optical cable 720 can be laid in an S-shaped manner above the liquid level to be measured, or can be laid around the outer wall of the storage tank. The specific laying method is stable according to actual needs and is not limited here. Through the device of this embodiment, the liquid level monitoring, gas leakage monitoring and high temperature monitoring functions can be integrated into one, making the application scenarios of the device more abundant, more practical, and cost-controlled.

In one embodiment, as shown in FIG7 , it further includes:

The second temperature-sensitive optical cable 830 is communicatively connected with the optical fiber demodulation device 810 , and the second temperature-sensitive optical cable 830 is laid in a circular manner above the liquid to be measured and parallel to the liquid surface.

When the temperature of the tank rises, some oil and gas will vaporize to the top of the tank with heat. The accumulation of heat on the top may cause a fire risk. Therefore, when measuring the temperature, the temperature of the top of the oil storage tank should also be monitored to provide timely warning to avoid fire and explosion. The installation method is to pass the temperature-sensing optical fiber through the galvanized pipe to the top of the tank, and then fix it to the guardrail on the top of the tank with a stainless steel tie. This method is to monitor the fire on the top of the oil tank and around the tank body. The temperature will be transmitted directly or through the tank body to the temperature-sensing optical fiber.

For example, real-time monitoring of leakage in floating roof tanks, which are composed of a floating roof floating on the surface of the medium and a vertical cylindrical tank wall. The floating roof rises and falls as the amount of medium in the tank increases or decreases. 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 to reduce the volatilization of the medium. The second temperature-sensitive optical cable is arranged near the sealing device. When the oil in the tank leaks, the overflowing oil will exchange heat 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, achieving the effect of accurately and quickly detecting abnormalities.

In this embodiment, as shown in Fig. 7, the second temperature-sensitive optical cable 830 and the first temperature-sensitive optical cable 820 are respectively connected to two channels of the optical fiber demodulation device 810. The second temperature-sensitive optical cable 830 can meet the needs of safety monitoring, and the first temperature-sensitive optical cable 810 can meet the needs of daily operation monitoring.

In one embodiment, it further includes:

A remote control terminal is connected to the optical fiber demodulation device for communication. The remote control terminal is loaded with preset control software and is used to remotely obtain the temperature of each preset position according to the preset control software.

In this embodiment, the remote control terminal can obtain the temperature data of the location monitored by 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.

Embodiment 2

In this embodiment, as shown in FIG3 , a liquid level monitoring method is provided, including:

Step 410, collecting optical signals at a plurality of preset positions on a target first temperature-sensitive optical cable according to a preset sampling interval, wherein the target first temperature-sensitive optical cable is laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured, and the first temperature-sensitive optical cable is at least partially exposed to the liquid surface of the liquid to be measured;

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 connected to the optical fiber demodulation device for communication, and the other end penetrates into the bottom of the liquid to be measured, thereby contacting the liquid to be measured at different depths, so that the temperature of the liquid to be measured at different depths affects the optical properties of the first temperature-sensitive optical cable, causing the transmitted optical signal to be attenuated, phase changed, or reflected/scattered.

When measuring temperature, the optical fiber demodulation device may 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 through 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 fiber core inside the first temperature-sensitive optical cable, thereby generating scattering phenomena of varying degrees.

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

Step 420, preprocessing the plurality of optical signals to obtain Raman scattering parameters of the optical signals, and calculating the temperature 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;

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

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

Step 430: Calculate the position of the liquid surface of the liquid to be tested based on the temperature of each of the preset positions.

In one embodiment, the step of calculating the position of the liquid level of the liquid to be measured based on the temperature of each of the preset positions includes:

Step 431, calculating the change rate of the temperature corresponding to adjacent preset positions;

Step 432, determining the liquid level according to the position information corresponding to multiple change rates whose change rates exceed a preset rising threshold and/or falling threshold.

It is understandable that the temperature sensed by the temperature-sensing optical cable when it is laid underground, the temperature sensed in the air outside the tank, the temperature sensed in the air inside the tank, and the temperature sensed in the liquid to be tested are all different. When the temperature-sensing optical cable enters the air inside the tank from the air outside the tank, the temperature usually changes in a non-smooth transition. Similarly, when the temperature-sensing optical cable enters the liquid to be tested from the air inside the tank, the temperature also changes in a transition. The change rates of these transitional temperatures are the multiple sub-change rates determined in the above method. Using this objective law, we can find the location where the temperature changes greatly, and combine it with the actual layout of the temperature sensing device to locate the liquid level.

In one embodiment, a temperature distribution diagram is generated based on the temperature information and the corresponding specific position, so as to help the user determine the position of the liquid level more intuitively. As shown in Figure 2, it is a temperature distribution diagram for monitoring the liquid level in a well. The temperature has multiple obvious turning points in different media. The first temperature-sensitive optical cable has the first temperature turning point at the point where it enters the wellhead from the external air. As the well depth increases, the temperature gradually increases until the first temperature-sensitive optical cable enters the well fluid, and the temperature again shows a discontinuous turning change. The position of this turning point is the position of the liquid level.

In one embodiment, the bubble aggregation in the liquid to be tested is determined by the temperature fluctuation in the temperature distribution diagram.

In this embodiment, as shown in FIG. 4 , the temperature inside the crude oil in an oil well is monitored. The fluctuating temperature value depicts the temperature change caused by the bubbles rising in the fluid, and the change in the fluctuation amplitude describes the phenomenon of the bubbles gathering from small to large.

In some chemical production processes, such as monitoring the liquid level in a reactor or fermentation tank, this method can monitor the liquid level and temperature while also detecting bubbles to ensure the stability of the reaction or fermentation process.

In one embodiment, after the step of calculating the position of the liquid level of the liquid to be measured based on the temperature of each of the preset positions, the method further comprises:

Detecting 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 issuing a first alarm when the change value of the liquid level position is greater than the liquid level change threshold;

and/or

Detecting whether the temperature value is greater than a temperature threshold; and issuing a second alarm when the temperature value is greater than the temperature threshold.

In this embodiment, the alarm device is connected to the optical fiber demodulation device for communication. When the temperature value related to the liquid to be tested in the temperature data analyzed by the optical fiber demodulation device exceeds the temperature threshold, it indicates that there is a fire risk, and the alarm device is activated accordingly; 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 that there is a leakage risk, and the alarm device is activated accordingly. The preset time period can be set to one day, one week, or one month, which is specifically set according to the actual monitoring needs and is not limited here.

It should be understood that, although the various steps in the flowchart of Fig. 3 are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps does not have a strict order restriction, and these steps can be executed in other orders. Moreover, at least a part of the steps in Fig. 3 may include a plurality of sub-steps or a plurality of stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily to be carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the sub-steps or stages of other steps.

Embodiment 3

In this embodiment, as shown in FIG5 , a liquid level monitoring device is provided, including:

A first temperature-sensitive optical cable 610, which is used to be laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured, wherein the first temperature-sensitive optical cable is at least partially exposed to the liquid surface of the liquid to be measured, wherein the first end of the first temperature-sensitive optical cable is located below the liquid surface 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;

A measuring host 620, the measuring host comprising 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 according to 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 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 temperature of each preset position; the display is used to communicate with the optical fiber demodulation device to display the temperature distribution diagram;

The user terminal 630 is used for communication connection with the measurement host. The user terminal is loaded with user terminal software, and the control and data call of the measurement host are realized through the user terminal software.

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

In the liquid level monitoring of each tank position of a large storage tank, the liquid level monitoring device corresponding to each tank can operate independently, and the output signal is summarized to the general dispatching room for centralized management. The system configuration is based on the needs of the site, and the data of each device is displayed in real time and transmitted to the monitor in the main control room (i.e. the user end) to intelligently analyze the fault trend of the monitored object, accurately locate the fault point, guide the maintenance work, and provide effective guarantee for the safe operation of the tank system.

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

The liquid level monitoring data of the four tanks are analyzed by the optical fiber demodulation equipment to generate corresponding temperature distribution diagrams, and each temperature distribution diagram is independently displayed on the measurement host. Through the temperature distribution diagram, the user can monitor the liquid level, storage temperature and bubbles inside the storage liquid at the same time, so as to timely discover safety risks such as fire and leakage.

In one embodiment, the measurement host communicates and interacts with the fire alarm, and can also interact with data from a third-party platform, actively transmitting alarms or zone temperatures to the outside world to provide timely risk alerts.

Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and 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-mentioned methods. Among them, any reference to memory, storage, database or other media used in the embodiments provided in this application can include non-volatile and/or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an 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 (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

The technical features of the above embodiments may be arbitrarily combined. To make the description concise, 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, they should be considered to be within the scope of this specification.

The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims (10)

1. A liquid level monitoring device, characterized in that it comprises a first temperature sensing optical cable and an optical fiber demodulation device, The first temperature-sensitive 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, and the first temperature-sensitive optical cable is at least partially exposed to the liquid surface of the liquid to be measured, wherein the first end of the first temperature-sensitive optical cable is located below the liquid surface 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; 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 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 obtain the position of the liquid level of the liquid to be measured based on the temperature calculation at each preset position. 2. The device according to claim 1 is 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 the optical fiber demodulation device is provided with multiple optical cable connection ports, and the second end of each of the first temperature-sensitive optical cables is correspondingly connected to each of the optical cable connection ports. 3 . The device according to claim 1 , wherein the first end of the first temperature-sensitive optical cable is coated with a waterproof layer. 4 . The device according to claim 1 , wherein 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, further comprising: 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 issues an alarm when the temperature value corresponding to the temperature signal exceeds a temperature threshold. 6. The device according to claim 1, further comprising: A display device is communicatively connected with 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 further comprises: The vibration optical cable is used to transmit the sound wave 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 claim 1, characterized in that the device further comprises: A second temperature-sensitive optical cable is communicatively connected to the optical fiber demodulation device, and the second temperature-sensitive optical cable is laid in a ring above the liquid to be measured parallel to the liquid surface. 9. The device according to any one of claims 1 to 8, further comprising: A remote control terminal is communicatively connected 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 temperature of each preset position according to the preset control software. 10. A liquid level monitoring method, comprising: Collecting optical signals at a plurality of preset positions on a target first temperature-sensitive optical cable according to a preset sampling interval, wherein the target first temperature-sensitive optical cable is laid in the liquid to be measured and is perpendicular to the liquid surface of the liquid to be measured, and the first temperature-sensitive optical cable is at least partially exposed to the liquid surface of the liquid to be measured; Preprocessing the plurality of optical signals to obtain Raman scattering parameters of the optical signals, and calculating the temperature 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; The position of the liquid level of the liquid to be measured is calculated based on the temperature of each of the preset positions.