Liquid-liquid layered interface and liquid level measurement method based on radar and differential pressure combination

Abstract

The application discloses an epoxy chloropropane and water liquid-liquid layered interface and liquid level measurement method based on radar and differential pressure. The method adopts a 80GHz frequency-modulated continuous wave radar installed on the tank top to measure the water-gas interface distance, calculate the total liquid level, and monitor the echo amplitude in real time; adopts a double-flange differential pressure transmitter to measure the differential pressure of the gas phase space between the tank bottom and the tank top; adopts a temperature sensor to measure the temperature in real time and correct the densities of water and epoxy chloropropane online. The total liquid level, differential pressure and corrected density are substituted into the static pressure equation, and the water layer height and the epoxy chloropropane layer height are obtained by simultaneous solution. When the echo amplitude is lower than the preset threshold, it is determined that there is an emulsion layer, the emulsion layer thickness is back calculated according to the echo amplitude attenuation rate, and three simultaneous static pressure equation groups are established to solve the water layer, emulsion layer and epoxy chloropropane layer height. The application realizes non-contact, corrosion-resistant liquid level and interface measurement, has emulsion layer compensation, temperature compensation and signal self-diagnosis functions, and is stable and reliable in measurement.

Description

Technical Field

[0001] This invention belongs to the field of liquid level measurement technology, specifically relating to a liquid-liquid separation interface and liquid level measurement method based on radar and differential pressure. Background Technology

[0002] In the production of epichlorohydrin (ECH), distillation dehydration is a crucial step in removing moisture from crude ECH. After distillation separation, water and ECH are allowed to separate into layers in a vertical storage tank at the top of the column. Because the density of ECH (approximately 1.18 g / cm³) is greater than that of water (approximately 1.00 g / cm³), a "water on top, ECH below" distribution is formed. To control separation efficiency and prevent product entrainment, it is necessary to monitor the total liquid level (water-gas interface) and the position of the water-ECH interface in real time.

[0003] Currently, the commonly used measurement schemes in existing technologies mainly include the following: 1. Single radar level gauge measurement scheme A non-contact radar level gauge is installed on the top of the tank. Because the dielectric constant of water (approximately 80) is much higher than that of ECH (approximately 7-10), electromagnetic waves experience significant attenuation when penetrating the upper water layer, resulting in a significantly weaker echo signal upon reaching the ECH surface. In actual operation, it was found that when the water layer thickness exceeds 1 meter or when fluctuations in ECH purity cause changes in the dielectric constant, the radar frequently experiences interface echo loss of lock, failing to stably output the total liquid level and accurately identify the interface between water and ECH. Furthermore, when an emulsion layer forms between the water and ECH layers due to temperature fluctuations or feed disturbances, the tiny droplets in the emulsion layer scatter and absorb radar waves, further attenuating the echo amplitude and exacerbating the signal loss problem.

[0004] 2. Single differential pressure level gauge measurement scheme A differential pressure transmitter is used to measure the differential pressure between the bottom and top of the tank. This method can only obtain the total static pressure value and cannot distinguish the individual heights of the water layer and the ECH layer. When process temperature fluctuations cause changes in the density of water or ECH, the correspondence between the differential pressure value and the liquid level shifts, resulting in a large measurement error and making it difficult to meet the requirements of accurate interface control.

[0005] 3. Magnetostrictive or float level gauge measurement scheme Interface measurement is performed using contact floats or magnetostrictive level gauges. ECH has strong chemical corrosiveness and permeability. Floats that are submerged in ECH for a long time are prone to corrosion, jamming, or changes in buoyancy, leading to frequent instrument failures, high maintenance costs, and the inability to achieve non-contact measurement.

[0006] In summary, existing technologies lack a non-contact measurement method that can simultaneously adapt to the density inversion characteristics of ECH-water, resist media corrosion, and stably output the total liquid level and interface height. In particular, when an emulsion layer exists between the water layer and the ECH layer, existing methods cannot effectively identify the presence of the emulsion layer and compensate for its measurement errors. Summary of the Invention

[0007] To address the aforementioned problems in existing technologies, this invention proposes a liquid-liquid stratification interface and liquid level measurement method based on radar and differential pressure. The method is rationally designed, overcomes the shortcomings of existing technologies, and has good performance.

[0008] A liquid-liquid separation interface and liquid level measurement method based on radar and differential pressure combined is applied to a vertical storage tank of an epichlorohydrin and water two-phase separation system, wherein water is the upper liquid and epichlorohydrin is the lower liquid. The method is characterized by the following steps: Step 1: Establish a measurement system, which includes a non-contact radar level gauge installed on the top of the tank, a differential pressure transmitter installed between the bottom and top of the tank, a temperature sensor installed on the side wall of the tank, and a computing unit connected to the radar level gauge, differential pressure transmitter, and temperature sensor. Step 2: Measure the distance from the radar antenna reference point to the water-air interface using the radar level gauge, and calculate the total liquid level height based on the total reference height of the storage tank; Step 3: Measure the differential pressure between the gas phase space at the bottom and top of the tank using the differential pressure transmitter and establish the static pressure equation; Step 4: Use the temperature sensor to measure the temperature of the medium inside the tank in real time, and correct the density of water and the density of epichlorohydrin according to the pre-calibrated density-temperature function; Step 5: Compare the amplitude value of the radar echo signal with a preset threshold: When the echo amplitude is greater than or equal to the preset threshold, it is determined that there is no emulsion layer or the thickness of the emulsion layer is negligible. The water layer height and epichlorohydrin layer height are solved by solving the two-phase simultaneous equations. When the echo amplitude is less than the preset threshold and greater than zero, it is determined that an emulsion layer exists. Based on the pre-calibrated correspondence between the echo amplitude attenuation rate and the emulsion layer thickness, the emulsion layer thickness is deduced from the current echo amplitude. Then, the height of the water layer, the height of the emulsion layer, and the height of the epichlorohydrin layer are solved using a set of three simultaneous static pressure equations including the water layer, the emulsion layer, and the epichlorohydrin layer. When the echo amplitude is zero or below the minimum detectable threshold, it is determined that the emulsion layer is too thick or the radar signal is completely ineffective, and the system automatically switches to standby mode. Step 6: Monitor the echo signal amplitude of the radar level gauge in real time. When the system switches to standby mode, suspend the use of radar measurement values, calculate the interface trend based on the historical data of the differential pressure transmitter and temperature sensor, and issue an alarm signal.

[0009] Furthermore, in step 2, the total liquid level height Calculate using the following formula: ; in, This is the reference total height of the storage tank. This is the distance from the radar antenna reference point to the water-air interface.

[0010] Furthermore, in step 3, the differential pressure The following static equations are satisfied: ; in, The density of water, The density of epichlorohydrin, It is the acceleration due to gravity. The height of the water layer. This represents the height of the epichlorohydrin layer.

[0011] Further, in step 4, the density-temperature function is: ; ; in, For standard reference temperature, , Water and ECH at standard temperatures, respectively. The density below, , These are the density temperature coefficients of water and ECH, respectively.

[0012] Furthermore, in step 5, the solution using a two-phase simultaneous equation specifically involves: based on the total liquid level relationship... The water layer height can be obtained by solving the hydrostatic equation using the following formula. and epichlorohydrin layer height : ; .

[0013] Furthermore, in step 5, the three-stage static pressure equation set includes: ; ; ; in, This is a pre-calibrated function relating the echo amplitude attenuation rate to the emulsion layer thickness. This represents the currently measured radar echo amplitude value. The height of the emulsion layer. This represents the equivalent density of the emulsion layer.

[0014] Furthermore, the equivalent density of the emulsion layer Calculate using the following formula: ; in, This represents the volume fraction of water in the emulsion layer.

[0015] Furthermore, the relationship between the echo amplitude attenuation rate and the emulsion layer thickness mentioned in step 5 is obtained through laboratory calibration: under the same tank structure and radar installation conditions, simulated emulsion layers of different thicknesses are prepared, the corresponding echo amplitude attenuation rates are measured, and calibration curves or lookup tables are established.

[0016] Furthermore, the radar level gauge is a frequency-hopping continuous wave radar with an operating frequency of not less than 80 GHz; The differential pressure transmitter is a dual-flange capillary type differential pressure transmitter, with its high-pressure side flange installed at the lowest point of the bottom of the storage tank and its low-pressure side flange installed in the gas phase space at the top of the storage tank. The diaphragm of the dual-flange capillary differential pressure transmitter is made of tantalum or Hastelloy, and the capillary filling fluid is inert fluorinated oil.

[0017] The temperature sensor is a Pt100 platinum resistance thermometer.

[0018] Furthermore, when the radar echo signal stabilizes and its amplitude exceeds the minimum detectable threshold, the system automatically switches back from standby mode to combined mode.

[0019] The beneficial technical effects of this invention are as follows: 1. Adaptable to density reversal conditions, stable and reliable measurement: Taking advantage of the fact that ECH has a density greater than that of water, this invention utilizes the characteristic of strong reflection of radar waves at the water-air interface (high dielectric constant difference) to measure the total liquid level. This avoids the signal attenuation and loss of lock caused by radar waves penetrating the heavy ECH layer in traditional solutions, thus ensuring the stability of the measurement signal.

[0020] 2. Achieve non-contact interface measurement and eliminate the effects of corrosion: This invention uses radar and differential pressure that do not need to be in direct contact with ECH (the differential pressure transmitter uses an isolation diaphragm), avoiding the problem of frequent damage to contact instruments such as floats and magnetostrictive instruments in the corrosive medium of ECH, reducing maintenance costs and equipment failure rate.

[0021] 3. Introducing temperature compensation to eliminate density fluctuation errors: By using online temperature measurement and density-temperature function correction, the density values ​​of water and ECH are corrected in real time, solving the problem that a single differential pressure level gauge cannot accurately distinguish the height of the two phases due to density drift caused by temperature changes, thus improving the accuracy of interface measurement.

[0022] 4. Emulsion layer identification and compensation capability: By analyzing the amplitude attenuation of radar echo signals, this invention can automatically determine whether an emulsion layer exists between the water layer and the ECH layer, and use the pre-calibrated correspondence between the echo amplitude attenuation rate and the emulsion layer thickness to infer the emulsion layer thickness. Then, a three-stage hydrostatic equation system is established to solve for the respective heights of the water layer, emulsion layer and ECH layer, effectively eliminating the error caused by the emulsion layer to the interface measurement and broadening the applicability of the method.

[0023] 5. Intelligent diagnostic and redundancy functions: Through self-diagnosis of echo signal quality, the system can automatically switch measurement modes when the radar signal is abnormal, preventing control failure due to temporary instrument malfunctions and enhancing the system's fault tolerance and security. Attached Figure Description

[0024] Figure 1 A flowchart of a liquid-liquid stratification interface and liquid level measurement method based on radar and differential pressure combined; Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to specific examples: A method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure, such as... Figure 1 As shown, a vertical storage tank is used in a two-phase stratified system of epichlorohydrin and water, wherein water is the upper liquid and epichlorohydrin is the lower liquid. Wherein: Water: Industrial water, density varies with temperature in the range of 997~1000 kg / m³ (0~40℃). Epichlorohydrin: purity ≥99.5%, density varies with temperature from 1.16 to 1.19 kg / m³ (0 to 40℃).

[0026] The measurement method includes the following steps: Step 1: Establish a measurement system, which includes a non-contact radar level gauge installed on the top of the tank, a differential pressure transmitter installed between the bottom and top of the tank, a temperature sensor installed on the side wall of the tank, and a computing unit connected to the radar level gauge, differential pressure transmitter, and temperature sensor. Among them, the vertical storage tank is used to hold the layered medium of epichlorohydrin and water, and the tank height is [missing information]. The cross-sectional area is uniform.

[0027] Radar level gauge: Installed on top of the storage tank, it is a non-contact frequency-modulated continuous wave (FMCW) radar with an operating frequency of not less than 80 GHz. This radar is used to measure the distance from the antenna reference point to the water-air interface. In this embodiment, an 80 GHz FMCW radar is selected, with a measurement accuracy of ±2 mm and a protection rating of IP67. Differential pressure transmitter: A dual-flange capillary type differential pressure transmitter is used. The high-pressure side flange is installed at the lowest point of the tank bottom, and the low-pressure side flange is installed in the gas phase space at the top of the tank. It is used to measure the differential pressure between the tank bottom and the gas phase. The differential pressure transmitter has a range of 0~50 kPa and an accuracy of ±0.075%. The diaphragm is made of tantalum or Hastelloy to resist ECH corrosion.

[0028] Temperature sensor: Installed in the middle of the side wall of the storage tank, used to measure the average temperature of the medium inside the tank in real time. This serves as the input parameter for density compensation. The temperature sensor is a Pt100 platinum resistance thermometer with an accuracy class A.

[0029] Calculation unit: Using a PLC or DCS control system, it receives signals from the radar level gauge, differential pressure transmitter and temperature sensor, performs logic operations and outputs the water layer height, ECH layer height and total liquid level.

[0030] Step 2: Measure the distance from the radar antenna reference point to the water-air interface using a radar level gauge, and calculate the total liquid level height based on the total reference height of the storage tank; The radar level gauge emits an 80 GHz frequency-modulated continuous wave, which penetrates the gas phase and the upper water layer sequentially. Because the dielectric constant of water (approximately 80) is much higher than that of ECH (approximately 7-10), the electromagnetic wave is strongly reflected at the water-gas interface, and the echo signal is received by the radar. Total liquid level height. Calculate using the following formula: ; in, This is the reference total height of the storage tank. This is the distance from the radar antenna reference point to the water-air interface.

[0031] at this time, That is, the height of the water layer. With ECH layer height sum: .

[0032] Step 3: Measure the differential pressure between the gas phase space at the bottom and top of the tank using the differential pressure transmitter and establish the static pressure equation; Differential pressure It equals the sum of the static pressure generated by the water layer and the static pressure generated by the ECH layer, satisfying the following static equation: ; in, The density of water, The density of epichlorohydrin, It is the acceleration due to gravity. The height of the water layer. This represents the height of the epichlorohydrin layer.

[0033] Step 4: Use the temperature sensor to measure the temperature of the medium inside the tank in real time. Since the density of water and the density of ECH both change with temperature, correct the density of water and the density of epichlorohydrin according to the pre-calibrated density-temperature function. The density-temperature function is: ; ; in, This is the standard reference temperature (usually 20℃). , Water and ECH at standard temperatures, respectively. The density below, , These are the density temperature coefficients of water and ECH, respectively.

[0034] Step 5: Compare the amplitude value of the radar echo signal with a preset threshold, which is determined based on on-site debugging. Establish a clear water-ECH stratification interface (without emulsion layer) in the storage tank and wait for the liquid level to stabilize; record the echo amplitude value output by the radar level gauge. Set the preset threshold to The threshold should be 30% to 50%, with the specific value determined through on-site debugging: if the system is too sensitive (frequent switching to standby mode), the threshold should be appropriately lowered; if an emulsion layer has appeared but the system has not switched, the threshold should be appropriately increased. When the echo amplitude is greater than or equal to the preset threshold, it is determined that there is no emulsion layer or the thickness of the emulsion layer is negligible. The water layer height and epichlorohydrin layer height are solved by solving the two-phase simultaneous equations. When the echo amplitude is less than the preset threshold and greater than zero, it is determined that an emulsion layer exists. Based on the pre-calibrated correspondence between the echo amplitude attenuation rate and the emulsion layer thickness, the emulsion layer thickness is deduced from the current echo amplitude. Then, the height of the water layer, the height of the emulsion layer, and the height of the epichlorohydrin layer are solved using a set of three simultaneous static pressure equations including the water layer, the emulsion layer, and the epichlorohydrin layer. When the echo amplitude is zero or below the minimum detectable threshold, it is determined that the emulsion layer is too thick or the radar signal is completely ineffective, and the system automatically switches to standby mode. The solution using a two-phase simultaneous equation is as follows: based on the total liquid level relationship... The water layer height can be obtained by solving the sum and differential pressure equations using the following formula. and epichlorohydrin layer height : ; .

[0035] The three-part static pressure equation set includes: ; ; ; in, The corresponding function of echo amplitude attenuation rate and emulsion layer thickness is pre-calibrated. The relationship between echo amplitude attenuation rate and emulsion layer thickness is obtained through laboratory calibration: under the same tank structure and radar installation conditions, simulated emulsion layers of different thicknesses are prepared, the corresponding echo amplitude attenuation rates are measured, and calibration curves or lookup tables are established. This represents the currently measured radar echo amplitude value. The height of the emulsion layer. This represents the equivalent density of the emulsion layer.

[0036] Equivalent density of emulsion layer Calculate using the following formula: ; in, The volume fraction of water in the emulsion layer was used to determine the echo amplitude attenuation rate and the water volume fraction in the emulsion layer through laboratory calibration. .

[0037] The calculation unit outputs the above calculation results to the control system for interface control, alarm, and process optimization.

[0038] Step 6: Monitor the echo signal amplitude of the radar level gauge in real time. When the system automatically switches to standby mode, it suspends the use of radar measurements, calculates the interface trend based on historical data from the differential pressure transmitter and temperature sensor, and issues an alarm signal to prompt instrument maintenance. After the echo signal stabilizes, the system automatically switches back to the combined operation mode.

[0039] Example: This method was used to measure the water washing tank in the epichlorohydrin production unit of a chemical company. The tank is a vertical cylindrical tank with a total height of 4230 mm, an inner diameter of 1600 mm, and a design pressure of atmospheric pressure.

[0040] 1. Equipment installation and parameter settings The radar level gauge uses an 80 GHz FMCW radar, which is installed at the center flange interface on the top of the tank. The measurement range is set to 200~3900 mm, that is, 200 mm below the top of the tank is the measurement blind zone, and the end point of the range is 3900 mm from the top of the tank. The empty height calibration is completed in the DCS system.

[0041] The differential pressure transmitter is a double-flange capillary type with a range of 0~43.78 kPa. The high-pressure side flange is installed at the lowest point of the tank bottom, and the low-pressure side flange is installed at the highest point of the gas phase space at the top of the tank. The capillary filling fluid is inert fluorinated oil, and the diaphragm material is tantalum to resist ECH corrosion.

[0042] The temperature sensor is a Pt100 platinum resistance thermometer, installed on the side wall of the tank 1500mm from the bottom of the tank, and the signal is connected to the DCS.

[0043] The computing unit uses a DCS control system, within which the aforementioned computing logic modules are programmed.

[0044] 2. Density calibration Under laboratory conditions, water and ECH samples were taken, and their densities were measured at a standard temperature of 20°C. Water: 998.2 kg / m³; ECH: 1180.0 kg / m³; The density temperature coefficient was calibrated through variable temperature experiments. Water: 0.21 kg / (m³·℃); ECH: 0.95 kg / (m³·℃); 3. Actual measurement process During a certain measurement, the process conditions were as follows: The internal temperature of the tank is 15℃; Radar level gauge output value: 63.8% (range 0-4230 mm, corresponding to a total liquid level of 2700 mm). Differential pressure level gauge output value: 68.3% (range 0-43.78 kPa, corresponding differential pressure 29.92 kPa); Temperature compensation calculation density: ; ; After receiving the above signals, the computing unit, combined with temperature-compensated density (water 999.25 kg / m³, ECH 1184.75 kg / m³), solves the simultaneous equations and finally outputs: Water level: 810 mm; Epichlorohydrin layer height: 1890 mm; 4. Result Verification To verify the accuracy of the measurement, the drain valve at the bottom of the tank was opened for inspection. The initial discharged medium was pure ECH, and discharge continued until the volume corresponding to a drop of 1890 mm in the liquid level was reached, after which the aqueous phase was discharged. The measurement results obtained by this method were consistent with those obtained through manual inspection.

[0045] 5. Handling Abnormal Operating Conditions When an emulsion layer appears between the water layer and the ECH layer, the radar level gauge echo amplitude decreases. If the echo amplitude is below a preset threshold but still detectable, the system automatically activates the emulsion layer compensation mode, inferring the emulsion layer thickness based on the echo amplitude attenuation rate, and using a three-stage hydrostatic equation system to solve for the heights of the water layer, emulsion layer, and ECH layer. If the echo amplitude is below the minimum detectable threshold, the system suspends the use of radar measurements and only calculates the interface position based on historical trends of differential pressure and temperature compensation. After the emulsion layer dissipates and the radar echo recovers, the system automatically switches back to the combined operation mode.

[0046] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the examples given above. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should also fall within the protection scope of the present invention.

Claims

1. A method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure combined, characterized in that, A vertical storage tank for a two-phase stratified system of epichlorohydrin and water, wherein water is the upper liquid and epichlorohydrin is the lower liquid, characterized by comprising the following steps: Step 1: Establish a measurement system, which includes a non-contact radar level gauge installed on the top of the tank, a differential pressure transmitter installed between the bottom and top of the tank, a temperature sensor installed on the side wall of the tank, and a computing unit connected to the radar level gauge, differential pressure transmitter, and temperature sensor. Step 2: Measure the distance from the radar antenna reference point to the water-air interface using the radar level gauge, and calculate the total liquid level height based on the total reference height of the storage tank; Step 3: Measure the differential pressure between the gas phase space at the bottom and top of the tank using the differential pressure transmitter and establish the static pressure equation; Step 4: Use the temperature sensor to measure the temperature of the medium inside the tank in real time, and correct the density of water and the density of epichlorohydrin according to the pre-calibrated density-temperature function; Step 5: Compare the amplitude value of the radar echo signal with a preset threshold: When the echo amplitude is greater than or equal to the preset threshold, it is determined that there is no emulsion layer, and the water layer height and epichlorohydrin layer height are solved by a two-phase simultaneous equation. When the echo amplitude is less than the preset threshold and greater than zero, it is determined that an emulsion layer exists. Based on the pre-calibrated correspondence between the echo amplitude attenuation rate and the emulsion layer thickness, the emulsion layer thickness is deduced from the current echo amplitude. Then, the height of the water layer, the height of the emulsion layer, and the height of the epichlorohydrin layer are solved using a set of three simultaneous static pressure equations including the water layer, the emulsion layer, and the epichlorohydrin layer. When the echo amplitude is zero or below the minimum detectable threshold, it is determined that the emulsion layer is too thick or the radar signal is completely ineffective, and the system automatically switches to standby mode. Step 6: Monitor the echo signal amplitude of the radar level gauge in real time. When the system switches to standby mode, suspend the use of radar measurement values, calculate the interface trend based on the historical data of the differential pressure transmitter and temperature sensor, and issue an alarm signal.

2. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 1, characterized in that, In step 2, the total liquid level height Calculate using the following formula: ； in, This is the reference total height of the storage tank. This is the distance from the radar antenna reference point to the water-air interface.

3. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 1, characterized in that, In step 3, the differential pressure The following static equations are satisfied: ； in, The density of water, The density of epichlorohydrin, It is the acceleration due to gravity. The height of the water layer. This represents the height of the epichlorohydrin layer.

4. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 1, characterized in that, In step 4, the density-temperature function is: ； ； in, For standard reference temperature, , Water and ECH at standard temperatures, respectively. The density below, , These are the density temperature coefficients of water and ECH, respectively.

5. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 1, characterized in that, In step 5, the solution using the two-phase simultaneous equations specifically involves: based on the total liquid level relationship... The water layer height can be obtained by solving the hydrostatic equation using the following formula. and epichlorohydrin layer height : ； 。 6. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 1, characterized in that, In step 5, the three-stage static pressure equation set includes: ； ； ； in, This is a pre-calibrated function relating the echo amplitude attenuation rate to the emulsion layer thickness. This represents the currently measured radar echo amplitude value. The height of the emulsion layer. This represents the equivalent density of the emulsion layer.

7. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 6, characterized in that, The equivalent density of the emulsion layer Calculate using the following formula: ； in, This represents the volume fraction of water in the emulsion layer.

8. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 6, characterized in that, The relationship between the echo amplitude attenuation rate and the emulsion layer thickness mentioned in step 5 is obtained through laboratory calibration: under the same tank structure and radar installation conditions, simulated emulsion layers of different thicknesses are prepared, the corresponding echo amplitude attenuation rates are measured, and calibration curves or lookup tables are established.

9. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 1, characterized in that, The radar level gauge is a frequency-hopping continuous wave radar with an operating frequency of not less than 80 GHz; The differential pressure transmitter is a dual-flange capillary type differential pressure transmitter, with its high-pressure side flange installed at the lowest point of the bottom of the storage tank and its low-pressure side flange installed in the gas phase space at the top of the storage tank. The diaphragm of the dual-flange capillary differential pressure transmitter is made of tantalum or Hastelloy, and the capillary filling fluid is inert fluorinated oil. The temperature sensor is a Pt100 platinum resistance thermometer.

10. The method for measuring liquid-liquid stratification interface and liquid level based on radar and differential pressure as described in claim 1, characterized in that, When the radar echo signal stabilizes and its amplitude exceeds the minimum detectable threshold, the system automatically switches back from standby mode to joint mode.

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