Ship oil-water separation oil tank with liquid level measurement function and liquid level measurement method

Abstract

The present invention discloses a ship oil-water separation oil tank with a liquid level measurement function and a liquid level measurement method, which includes an oil tank. An oil bladder is connected to the inner wall of the top of the oil tank; the oil-water separation oil tank further includes a pipeline system. The pipeline system includes an oil pipeline communicating with the inside of the oil bladder and a water pipeline communicating with the inside of the oil tank. Flow sensors are provided on both the oil pipeline and the water pipeline; a plurality of pressure sensors are provided on the inner wall of the bottom of the oil tank, and a plurality of ultrasonic sensors are provided on the inner wall of the top of the oil tank; the oil-water separation oil tank further includes a liquid level monitoring box. The liquid level monitoring box includes a data processing module. The pressure sensors and the ultrasonic sensors are both connected to the data processing module. The data processing module is used to calculate the liquid level height of the water in the oil tank and the liquid level height of the oil in the oil bladder according to the data measured by the pressure sensors and the ultrasonic sensors. The present invention can obtain the liquid level height and volume of water and oil in the oil tank in real time and improve the accuracy of oil quantity detection.

Description

Technical Field

[0001] The present invention relates to the field of detecting the liquid level of oil and water in a ship's oil tank, and specifically to a liquid level detection device and method for an oil tank of a ship with oil-water isolation and replacement. Background Art

[0002] With the rapid development of China's economy and foreign trade, the domestic demand for ships shows a continuous growth trend. Improving the utilization efficiency of fuel when the ship's displacement is equal plays an important role in reducing operating costs. In order to prevent pollution caused by traditional oil-water replacement and underwater oil storage, people have begun to use oil bags with oil-water isolation and replacement to store oil. However, the current detection of the oil tank still uses a contact liquid level detector, and the rocking state of the ship at sea, the state of loading and unloading oil, and the current shape of the oil tank are also more irregular, greatly increasing the difficulty of detecting the liquid level of the oil tank and measuring the total amount of oil loaded.

[0003] The Chinese patent with the publication number CN111750278A discloses an invention of a ship oil tank liquid level monitoring and protection system. The system includes a plurality of liquid level switches, which are arranged on each fuel tank. The liquid level switches are sequentially connected to a controller and a relay control unit. The relay control unit is connected to an electric valve control circuit and an alarm. An inlet valve and an inlet electric valve are provided on the inlet oil to the tank. A protection electric valve is connected in parallel at both ends of the inlet valve and the inlet electric valve. The inlet oil pipe is connected to a fuel filling port through a filling flow switch and a filling valve. When the liquid level of a certain fuel tank exceeds the liquid level switch, the controller controls the inlet electric valve of the fuel tank to close and controls the alarm to give an alarm, and controls the protection electric valves of other fuel tanks with a liquid level lower than the liquid level switch to open. However, this invention only considers the liquid level detection and protection during the process of loading and unloading oil in the oil tank, and cannot accurately and real-time detect the liquid level heights of water and oil during the operation of the ship.

[0004] The Chinese patent with the publication number CN113532587A discloses an invention of a sensor for measuring the liquid level position in a marine fuel tank and its working method; the sensor includes a mounting mechanism, a protection cylinder, a rectangular partition, a first capacitance measurement probe, a second capacitance measurement probe and a processing module; the second capacitance measurement probe is wrapped by an insulating layer and the bottom end position of the second capacitance measurement probe is lower than the bottom end position of the first capacitance measurement probe, so that based on the conventional capacitance detection and liquid level height measurement principles after the sensor is installed; according to the fitting function of the calibration data and the two capacitance measurement values collected by the two capacitance measurement probes with different lengths, the fuel liquid level position and the oil-water interface position corresponding to the two capacitance measurement values are determined, so as to achieve the purpose of monitoring the bilge flooding and simultaneously measuring the fuel liquid level, and further improve the safety and anti-damage management ability of the ship operation. However, this invention is in contact with both water and oil, and cannot avoid the pollution caused by the contact between water and oil, and does not solve the problem of traditional oil-water replacement. Summary of the Invention

[0005] To overcome the deficiencies of the above-mentioned prior art, the present invention provides a ship oil-water separation oil tank with a liquid level measurement function and a liquid level measurement method to solve at least one of the above technical problems.

[0006] Based on one aspect of the present invention, there is provided a ship oil-water separation oil tank with a liquid level measurement function, including an oil tank, and an oil bladder is connected to the inner wall of the top of the oil tank; the oil-water separation oil tank further includes a pipeline system, and the pipeline system includes an oil delivery pipeline communicating with the inside of the oil bladder and a water delivery pipeline communicating with the inside of the oil tank. Flow sensors are provided on both the oil delivery pipeline and the water delivery pipeline; a plurality of pressure sensors are provided on the inner wall of the bottom of the oil tank, and a plurality of ultrasonic sensors are provided on the inner wall of the top of the oil tank; the oil-water separation oil tank further includes a liquid level monitoring box, and the liquid level monitoring box includes a data processing module. The pressure sensors and the ultrasonic sensors are both connected to the data processing module, and the data processing module is used to calculate the liquid level height of the water in the oil tank and the liquid level height of the oil in the oil bladder according to the data measured by the pressure sensors and the ultrasonic sensors.

[0007] In the above technical solution, the space inside the oil bladder is used to load oil, and the space between the oil bladder and the oil tank is used to load seawater, thus realizing the isolated storage of oil and water. At the same time, an ultrasonic sensor is used to measure the height from the oil surface in the oil bladder to the top of the oil tank and the height from the bottom of the oil bladder to the top of the oil tank; a pressure sensor is used to measure the water pressure in the oil tank, and the liquid level height of the water is calculated using the water pressure formula.

[0008] Further, the liquid level monitoring box further includes a control module and an alarm module. The control module is connected to the data processing module and the alarm module. When the liquid level height of the water and / or the liquid level height of the oil calculated by the data processing module exceeds the set threshold, the control module controls the alarm module to give an alarm.

[0009] The alarm module gives an alarm when the liquid level height exceeds the warning height to remind the staff to drain the oil or water in time to avoid dangerous situations.

[0010] Further, the alarm module is an audible and visual alarm.

[0011] The audible and visual alarm can give an alarm in various forms and can more effectively warn the staff.

[0012] Further, the oil delivery pipeline includes an oil injection pipeline and an oil discharge pipeline, and flow sensors are provided on both the oil injection pipeline and the oil discharge pipeline.

[0013] Dividing the oil delivery pipeline into an oil injection pipeline and an oil discharge pipeline can adapt to the situation where oil needs to be injected into the oil tank while pumping oil out of the oil tank.

[0014] Further, the water conveyance pipeline includes a water injection pipeline and a drainage pipeline, and flow sensors are arranged on both the water injection pipeline and the drainage pipeline.

[0015] Dividing the water conveyance pipeline into a water injection pipeline and a drainage pipeline can adapt to the situation where it is necessary to inject water into the oil tank while draining water from the oil tank.

[0016] The data processing module is further configured to calculate the volume of water in the oil tank and the volume of oil in the oil bladder according to the liquid level height of water in the oil tank and the liquid level height of oil in the oil bladder.

[0017] By calculating the volume of water and the volume of oil in the oil tank, the volume of the liquid in the oil tank can be grasped in real time, which can provide data support for grasping the weight balance during the ship's navigation.

[0018] Based on another aspect of the present invention, a liquid level measurement method is provided, including the following steps:

[0019] S1: Obtain the water pressure P measured by the pressure sensor, the distance h from the oil liquid surface to the top of the oil tank measured by the ultrasonic sensor, and the height H from the bottom of the oil bladder to the top of the oil tank at the current moment;

[0020] S2: Based on the water pressure P, use the water pressure formula P = ρgh to calculate the liquid level height h1 of water; use H - h to calculate the liquid level height h2 of oil at a single point; determine whether oil is being loaded or unloaded in the oil bladder at the current moment. If so, proceed to step S3;

[0021] S3: Obtain the total volume of oil loaded or unloaded from the start of loading or unloading oil to the current moment, and calculate the change Δh in the oil liquid level height according to the tank volume curve of the oil bladder and the total volume of oil loaded or unloaded;

[0022] S4: Obtain the liquid level height d1 of oil at the start of this loading or unloading operation, calculate the height value d2 through d1 + Δh, and take the average value of h2 and d2 as the optimized value of the liquid level height of oil at a single point in the oil bladder at the current moment, then end.

[0023] In the above technical solution, according to physical principles, when the liquid level height of water in the oil tank changes, the pressure data measured by the pressure sensor also changes accordingly. Therefore, based on the pressure data measured by the pressure sensor located at the bottom of the oil tank and the water pressure formula, the liquid level height of water in the oil tank can be calculated. Since the densities of gas, oil, and the oil bladder are different, when ultrasonic waves are transmitted to the surface of the oil, part of the ultrasonic waves will be reflected and obtained, so that the distance from the oil liquid surface to the ultrasonic sensor (i.e., the distance h from the oil liquid surface to the top of the oil tank) can be obtained. When the ultrasonic waves are transmitted to the position where the oil contacts the oil bladder, the ultrasonic waves are reflected back, so that the distance between the bottom of the oil bladder and the ultrasonic sensor (i.e., the height H from the bottom of the oil bladder to the top of the oil tank) can be obtained. The difference between the two (i.e., H - h) is the liquid level height h2 of oil at a single point.

[0024] If oil loading and unloading (loading and unloading oil) is in progress at the current moment, the detection of the liquid level height of the oil will be affected by the oil loading and unloading. Therefore, the liquid level height of the oil before the start of oil loading and unloading can be obtained by the above method first. Based on the total volume of oil loading and unloading counted by the flowmeter, and combined with the tank volume curve of the oil bladder, the change in the liquid level height of the oil Δh can be obtained (Δh is positive during oil loading and negative during oil unloading). Adding the liquid level height of the oil before oil loading and unloading to the change in the liquid level height can obtain the current liquid level height of the oil (that is, the optimized value of the liquid level height of the oil at a single point in the oil bladder at the current moment).

[0025] Further, in step S2, if it is determined that there is no oil loading and unloading in the oil bladder at the current moment, then go to step S5

[0026] S5: Advance the time t, where t is the time from the most recent stop of oil loading and unloading to the current moment. Divide the t period evenly into n time points t1, t2, t3... t n , and obtain the liquid level height of the oil corresponding to each time point at a single point a1, a2, a3... a n ;

[0027] S6: Calculate and obtain the a corresponding to the minimum n and a n-1 , and take the average value of a n and a n-1 as the optimized value of the liquid level height of the oil at a single point at the current moment.

[0028] From the stop of the last oil loading and unloading to the current moment, the volume of the oil in the oil tank remains unchanged. Since the ship is in a rocking state during navigation, the measured values of the liquid level height of the oil at different moments are different. The average value of the liquid level height of the oil at two adjacent moments when the ship is running most smoothly (that is the a corresponding to the minimum n and a n-1 ) is used as the liquid level height of the current oil, and the obtained result is the most accurate.

[0029] Further, the method further includes calculating the volume of water and oil in a single oil tank based on the optimized value of the liquid level height of the oil at all single points at the current moment and the liquid level height of the water in the oil tank. The specific steps are as follows:[

[0030] S7: Obtain the position information of each pressure sensor and ultrasonic sensor, the shape characteristics of the oil tank, and the attitude characteristics of the oil tank, and convert the measured liquid level height of the water h1 and the optimized value of the liquid level height of the oil at each point into coordinate points;

[0031] S8: Perform cubic spline interpolation based on the coordinate data of each point position, fit the interpolated points and each point position to obtain the water-air surface, oil-water surface, oil-air surface, and oil-oil bladder surface, and simultaneously obtain the water-air surface equation, oil-water surface equation, oil-air surface equation, and oil-oil bladder surface equation; the water-air surface, oil-water surface, and the inner wall of the cabin enclose to form the three-dimensional shape of water, and the oil-air surface and oil-oil bladder surface enclose to form the three-dimensional shape of oil;

[0032] S9: Perform three-dimensional integration on the three-dimensional shape of oil to obtain the volume of oil in a single oil tank; perform three-dimensional integration on the three-dimensional shape of water to obtain the volume of water in a single oil tank.

[0033] Regard the bottom and top of the oil tank as two horizontal coordinate systems respectively (the origins of the two horizontal coordinate systems coincide vertically), and obtain the X coordinate and Y coordinate of each sensor on the horizontal coordinate system. The X coordinate and Y coordinate of the sensor are the X coordinate and Y coordinate of its corresponding measurement point position, and the liquid level depth of the measurement point position (the liquid level depth of water or the liquid level depth of oil) is the Z coordinate of the measurement point position. By this method, each point position can be converted into a coordinate point, and the three-dimensional coordinate data of each coordinate point can be obtained.

[0034] Furthermore, the method further includes calculating the total volume of oil in the current ship based on the volume of oil in a single oil tank. The specific steps are as follows:

[0035] S10: Determine whether oil is being loaded or unloaded at the current moment. If not, proceed to step S11; if so, proceed to step S12;

[0036] S11: Obtain the volume of oil in each oil tank when the last oil loading or unloading stopped, sum up the volumes of oil in each oil tank to obtain the total volume of oil V1 in the ship when the last oil loading or unloading stopped. Calculate the total oil loss volume ΔV1 of the ship from the last oil loading or unloading stop to the current moment according to the daily oil loss rate of the ship. Then the total volume of oil in the ship at the current moment is V1 - ΔV1, and the calculation ends;

[0037] S12: Obtain the volume of oil in each oil tank before the start of this oil loading or unloading, sum up the volumes in each oil tank to obtain the total volume of oil V2 in the ship before the start of this oil loading or unloading;

[0038] S13: Obtain the total loading volume ΔV2 and the total oil discharge volume ΔV3 from the start of oil loading or unloading to the current moment according to the flow data of the flowmeter; then the total volume of oil in the current ship is V2 + ΔV2 - ΔV3, and the calculation ends.

[0039] The daily oil loss rate includes the oil consumption of the ship itself and the evaporation amount of oil. The loading volume refers to the amount of oil loaded into the ship from outside the ship, and the unloading volume refers to the amount of oil discharged from the ship to outside the ship.

[0040] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0041] (1) A ship oil-water separation oil tank with a liquid level measurement function provided by the present invention physically separates water and oil by using an oil bladder, reducing the pollution problem of seawater caused by water-oil contact during traditional oil-water separation and replacement when water is discharged, and also ensuring the quality of oil. Moreover, the water-oil tank body is integrated, improving the fuel loading capacity of the ship. At the same time, an ultrasonic sensor is used to measure the height from the oil surface in the oil bladder to the top of the oil tank and the height from the bottom of the oil bladder to the top of the oil tank; a pressure sensor is used to measure the water pressure in the oil tank, and the water level height is calculated by using the water pressure formula, so as to obtain the water level height and the oil level height in the oil tank in real time.

[0042] (2) The liquid level measurement method provided by the present invention sets a three-level algorithm based on considering the working conditions of the ship oil tank. First, a single liquid level sensor is used to detect the liquid level height at a single point, then multiple liquid level sensors are used to detect the volume of a single oil tank, and finally, multiple liquid level sensors on a single ship are used to detect the total volume of multiple oil tanks. The three-level algorithms match and progress layer by layer, thus greatly improving the calculation efficiency of the oil quantity.

[0043] (3) By considering the structural characteristics of the oil tank and the changes in ship attitudes such as the roll angle, pitch angle, and acceleration of the ship, the present invention improves the accuracy of oil quantity detection.

[0044] (4) By performing third-order spline interpolation on the oil-water interface space coordinate data obtained by the sensor and smoothing the obtained coordinates, integrating with the tank volume curve, and performing three-dimensional integration on the tank bottom-water surface and water surface-oil surface, the volume and three-dimensional shape are obtained, greatly improving the accuracy of non-contact liquid level detection in the ship oil tank. Brief Description of the Drawings

[0045] Figure 1 Schematic diagram of the structure of a ship oil-water separation oil tank according to an embodiment of the present invention;

[0046] Figure 2 Flowchart of the oil-water liquid level measurement method for a single oil tank according to an embodiment of the present invention;

[0047] Figure 3 Flowchart of the oil-water volume detection method for a single oil tank according to an embodiment of the present invention;

[0048] Figure 4 Flowchart of the detection method for the total oil loading capacity of a ship oil tank according to an embodiment of the present invention;

[0049] Figure 5 Schematic diagram of the oil tank control principle according to an embodiment of the present invention;

[0050] Figure 6Sensor location layout diagram according to an embodiment of the present invention;

[0051] Figure 7 Oil-water separation oil tank composition diagram according to an embodiment of the present invention.

[0052] In the figure: 1, oil tank; 101, water injection pipeline; 102, drainage pipeline; 103, breather valve; 2, oil bladder; 201, oil injection pipeline; 202, oil discharge pipeline; 3, ultrasonic sensor; 4, pressure sensor. Detailed implementation manners

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts fall within the scope of protection of the present invention.

[0054] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more unless otherwise specifically defined.

[0055] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection or can communicate with each other; it may be directly connected, or indirectly connected through an intermediate medium, and may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include the direct contact between the first and second features, or may include the situation where the first and second features are not in direct contact but in contact through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes that the first feature is directly above and obliquely above the second feature, or merely indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or merely indicates that the horizontal height of the first feature is less than that of the second feature.

[0057] Embodiment 1

[0058] As Figure 1 and Figure 7 shown, this embodiment provides a ship oil-water separation oil tank with a liquid level measurement function, including an oil tank 1, and an oil bladder 2 is connected to the inner wall of the top of the oil tank 1; the oil-water separation oil tank further includes a pipeline system, the pipeline system includes an oil pipeline communicating with the inside of the oil bladder 2 and a water pipeline communicating with the inside of the oil tank 1, and flow sensors are arranged on both the oil pipeline and the water pipeline; as Figure 6 shown, a plurality of pressure sensors 4 are arranged on the inner wall of the bottom of the oil tank 1, and a plurality of ultrasonic sensors 3 are arranged on the inner wall of the top of the oil tank 1; the oil-water separation oil tank 1 further includes a liquid level monitoring box, the liquid level monitoring box includes a data processing module, the pressure sensors 4 and the ultrasonic sensors 3 are both connected to the data processing module, and the data processing module is used for calculating the liquid level height of water in the oil tank 1 and the liquid level height of oil in the oil bladder 2 according to the data measured by the pressure sensors 4 and the ultrasonic sensors 3.

[0059] The oil bladder 2 is made of a flexible diaphragm and has the property of isolating oil and water. The space inside the oil bladder 2 is used for loading oil, and the space between the oil bladder 2 and the oil tank 1 is used for loading seawater, thus realizing the isolated storage of oil and water.

[0060] This embodiment uses the ultrasonic sensor 3 (ultrasonic liquid level gauge in this embodiment) to measure the height from the oil surface in the oil bladder 2 to the top of the oil tank 1 and the height from the bottom of the oil bladder 2 to the top of the oil tank 1, uses the pressure sensor 4 (40PC100G2A type pressure sensor 4) to measure the water pressure in the oil tank 1, and calculates the liquid level height of water by using the water pressure formula.

[0061] As Figure 5 shown, in this embodiment, the liquid level monitoring box is connected to a signal control box, the signal control box collects the signals transmitted by each sensor and transmits the signals to the liquid level monitoring box, and the signal control box is also used for supplying power to each sensor.

[0062] The liquid level monitoring box further includes a display screen for displaying the collected monitoring data, as well as the calculated liquid level data and volume data, facilitating the staff to intuitively understand the liquid level and volume conditions in the oil tank 1.

[0063] The liquid level monitoring box further includes a data storage module for storing the detection data, as well as the calculated liquid level height data and liquid volume data, which is convenient for later viewing and verification.

[0064] As a preferred embodiment, the liquid level monitoring box further includes a control module and an alarm module. The control module is connected to the data processing module and the alarm module. When the liquid level height of water and / or the liquid level height of oil calculated by the data processing module exceeds the set threshold, the control module controls the alarm module to give an alarm.

[0065] The alarm module gives an alarm when the liquid level height exceeds the warning height to remind the staff to drain the oil or water in time to avoid potential risks.

[0066] As a preferred embodiment, the alarm module is an audible and visual alarm.

[0067] The audible and visual alarm can give an alarm in various forms and can more effectively alert the staff.

[0068] As a preferred embodiment, the oil pipeline includes an oil injection pipeline 201 and an oil drainage pipeline 202, and flow sensors are arranged on both the oil injection pipeline 201 and the oil drainage pipeline 202.

[0069] Dividing the oil pipeline into the oil injection pipeline 201 and the oil drainage pipeline 202 can adapt to the situation where oil needs to be loaded into the oil tank 1 while unloading oil from the oil tank 1.

[0070] As a preferred embodiment, the water pipeline includes a water injection pipeline 101 and a water drainage pipeline 102, and flow sensors are arranged on both the water injection pipeline 101 and the water drainage pipeline 102.

[0071] Dividing the water pipeline into the water injection pipeline 101 and the water drainage pipeline 102 can adapt to the situation where water needs to be injected into the oil tank 1 while draining water from the oil tank 1.

[0072] As a preferred embodiment, a filter is arranged on the water injection pipeline 101, and the filter is used to ensure that the injected water does not contain impurities such as particulate matter.

[0073] As a preferred embodiment, a breather valve 103 is arranged on the oil tank 1, and the breather valve 103 is internally connected to the oil bladder 2. The breather valve 103 is used to prevent overpressure or underpressure in the oil bladder 2.

[0074] As a preferred embodiment, the data processing module is further configured to calculate the volume of water in the oil tank 1 and the volume of oil in the oil bladder 2 according to the liquid level height of water in the oil tank 1 and the liquid level height of oil in the oil bladder 2.

[0075] By calculating the volume of water and the volume of oil in the oil tank 1, the volume of liquid in the oil tank 1 can be grasped in real time, which can provide data support for grasping the weight distribution during the navigation of the ship.

[0076] Embodiment 2

[0077] As Figure 2 and Figure 3 shown, this embodiment provides a liquid level measurement method, including the following steps:

[0078] S1: Obtain the water pressure P measured by the pressure sensor, the distance h from the oil liquid level to the top of the oil tank measured by the ultrasonic sensor, and the height H from the bottom of the oil bladder to the top of the oil tank at the current moment;

[0079] S2: Based on the water pressure P, use the water pressure formula P = ρgh to calculate the liquid level height of water (the height from the bottom of the tank to the water surface) h1; use H - h to calculate the liquid level height of oil at a single point (the height from the bottom of the oil bladder to the oil surface) h2; determine whether oil is being loaded or unloaded in the oil bladder at the current moment. If so, proceed to step S3;

[0080] S3: Obtain the total volume of oil loaded or unloaded from the start of loading or unloading oil to the current moment, and calculate the change in oil liquid level height Δh according to the tank volume curve of the oil bladder and the total volume of oil loaded or unloaded;

[0081] S4: Obtain the liquid level height d1 of oil at the start of this loading or unloading of oil, calculate the height value d2 through d1 + Δh (when loading oil) or d1 - Δh (when unloading oil), and take the average of h2 and d2 as the optimized value of the liquid level height of oil at a single point in the oil bladder at the current moment, then end.

[0082] Before the ship leaves the factory, the first tank volume curve for oil and the second tank volume curve for water are obtained through experiments. The abscissa of the first tank volume curve is the liquid level height of oil, and the ordinate is the volume of oil; the abscissa of the second tank volume curve is the liquid level height of water in the oil tank, and the ordinate is the volume of water. The volume of water at any moment is the volume of the entire oil tank minus the volume of oil in the oil bladder.

[0083] According to physical principles, when the liquid level height of the water in the oil tank changes, the pressure data measured by the pressure sensor also changes accordingly. Therefore, based on the pressure data measured by the pressure sensor located at the bottom of the oil tank and the water pressure formula, the liquid level height of the water in the oil tank can be calculated. Due to the different densities of the three substances, gas, oil, and oil bladder, when ultrasonic waves are transmitted to the surface of the oil, part of the ultrasonic waves will be reflected and obtained, so that the distance from the oil liquid surface to the ultrasonic sensor (i.e., the distance h from the oil liquid surface to the top of the oil tank) can be obtained. When the ultrasonic waves are transmitted to the position where the oil contacts the oil bladder, the ultrasonic waves are reflected back, so that the distance between the bottom of the oil bladder and the ultrasonic sensor (i.e., the height H from the bottom of the oil bladder to the top of the oil tank) can be obtained. The difference between the two (i.e., H - h) is the liquid level height h2 of the oil at a single point.

[0084] If oil loading and unloading (loading oil and unloading oil) is in progress at the current moment, the detection of the oil liquid level height will be affected by the oil loading and unloading. Therefore, the oil liquid level height before the start of oil loading and unloading can be obtained by the above method first. Based on the total volume of oil loading and unloading counted by the flow meter and combined with the tank volume curve of the oil bladder, the change in the oil liquid level height Δh can be obtained. Adding or subtracting the oil liquid level height before oil loading and unloading from the change in the oil liquid level height can obtain the current oil liquid level height (i.e., the optimized value of the oil liquid level height at a single point in the oil bladder at the current moment).

[0085] As a preferred implementation manner, in step S2, if it is determined that there is no oil loading and unloading in the oil bladder at the current moment, then step S5 is entered.

[0086] S5: Advance the time t, where t is the time from the most recent stop of oil loading and unloading to the current moment. Divide the t period evenly into n time points t1, t2, t3...t n and obtain the oil liquid level height a1, a2, a3...a corresponding to each time point at a single point. n ;

[0087] S6: Calculate and obtain the a corresponding to the minimum n and a n-1 and take the average value of a n and a n-1 as the optimized value of the oil liquid level height at a single point at the current moment.

[0088] From the stop of the last oil loading and unloading to the current moment, the volume of the oil in the oil tank remains unchanged. Since the ship is in a rocking state during the voyage, the measured values of the oil liquid level height at different moments are different. The oil liquid level heights at two adjacent moments when the ship is running most smoothly (i.e., the a corresponding to the minimum n and a n-1) The average value is the current liquid level height of the oil, and the obtained result is the most accurate.

[0089] As a preferred embodiment, as Figure 4 shown, the method provided in this embodiment further includes calculating the volume of water and oil in a single oil tank based on the optimized values of the liquid level height of the oil at all single points and the liquid level height of the water in the oil tank at the current moment. The specific steps are as follows:

[0090] S7: Obtain the position information of each pressure sensor and ultrasonic sensor, the shape characteristics of the oil tank, and the attitude characteristics of the oil tank, and convert the measured optimized values of the liquid level height of the water and the liquid level height of the oil at each point into coordinate points;

[0091] S8: Perform cubic spline interpolation according to the coordinate data of each point, fit the interpolated points and each point to form a water-air surface, an oil-water surface, an oil-air surface, and an oil-oil bladder surface, and obtain the water-air surface equation, the oil-water surface equation, the oil-air surface equation, and the oil-oil bladder surface equation at the same time; The water-air surface, the oil-water surface, and the inner wall of the tank enclose to form the three-dimensional shape of the water, and the oil-air surface and the oil-oil bladder surface enclose to form the three-dimensional shape of the oil;

[0092] S9: Perform three-dimensional integration on the three-dimensional shape of the oil to obtain the volume of the oil in a single oil tank; perform three-dimensional integration on the three-dimensional shape of the water to obtain the volume of the water in a single oil tank. In this embodiment, after obtaining the volume of the oil and water in a single oil tank, compare the calculated value with the ideal value under the standard verification state. If the error is less than 0.0003, output the calculated volume data. If the error is greater than 0.0003, return to step S1. Before the ship leaves the factory, obtain the data relationship (i.e., the tank capacity curve) between the liquid level height and the liquid volume through experiments in a stationary state. The liquid volume obtained based on the data relationship and the liquid level height is the ideal value.

[0093] Regard the bottom and top of the oil tank as two horizontal coordinate systems respectively (the origins of the two horizontal coordinate systems coincide vertically), and obtain the X coordinate and Y coordinate of each sensor on the horizontal coordinate system. The X coordinate and Y coordinate of the sensor are the X coordinate and Y coordinate of its corresponding measurement point, and the liquid level depth (the liquid level depth of the water or the liquid level depth of the oil) of the measurement point is the Z coordinate of the measurement point. Through this method, each point can be converted into a coordinate point, and the three-dimensional coordinate data of each coordinate point can be obtained.

[0094] As a preferred implementation manner, the method further includes calculating the total volume of the oil in the current ship based on the volume of the oil in a single oil tank. The specific steps are as follows:

[0095] S10: Determine whether oil is being loaded or unloaded at the current moment. If not, enter step S11. If so, enter step S12;

[0096] S11: Obtain the volume of oil in each oil tank at the last stop of loading and unloading oil, sum up the volumes of oil in each oil tank to obtain the total volume of oil V1 in the ship at the last stop of loading and unloading oil, calculate the total loss of oil volume ΔV1 in the ship from the last stop of loading and unloading oil to the current moment according to the daily oil loss rate of the ship, then the total volume of oil in the ship at the current moment is V1 - ΔV1, and the calculation ends;

[0097] S12: Obtain the volume of oil in each oil tank before the start of this loading and unloading operation, sum up the volumes in each oil tank to obtain the total volume of oil V2 in the ship before the start of this loading and unloading operation;

[0098] S13: Obtain the total amount of loaded oil ΔV2 and the total amount of unloaded oil ΔV3 from the start of loading and unloading oil to the current moment according to the flow rate data of the flowmeter; then the total volume of oil in the current ship is V2 + ΔV2 - ΔV3, and the calculation ends.

[0099] As a preferred implementation manner, after obtaining the total volume of oil in the ship, determine whether the total volume of oil is greater than the sum of the volumes of all oil tanks of the ship. If not, output the volume data of the oil. If so, the alarm module gives an alarm.

[0100] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A liquid level measurement method for realizing the liquid level measurement of the oil-water separation oil tank of a ship with liquid level measurement function, characterized in that, The ship oil-water separation oil tank with liquid level measurement function includes an oil tank, and an oil bladder is connected to the inner wall of the top of the oil tank; the oil-water separation oil tank further includes a pipeline system, which includes an oil pipeline connected to the inside of the oil bladder and a water pipeline connected to the inside of the oil tank. Flow sensors are arranged on both the oil pipeline and the water pipeline; a number of pressure sensors are arranged on the inner wall of the bottom of the oil tank, and a number of ultrasonic sensors are arranged on the inner wall of the top of the oil tank; the oil-water separation oil tank further includes a liquid level monitoring box, and the liquid level monitoring box includes a data processing module. The pressure sensors and ultrasonic sensors are both connected to the data processing module, and the data processing module is used to calculate the liquid level height of water in the oil tank and the liquid level height of oil in the oil bladder according to the data measured by the pressure sensors and ultrasonic sensors; The liquid level measurement method includes the following steps: S1: Obtain the water pressure P measured by the pressure sensor, the distance h from the oil liquid surface to the top of the oil tank measured by the ultrasonic sensor, and the height H from the bottom of the oil bladder to the top of the oil tank at the current moment; S2: Based on the water pressure P, use the water pressure formula to calculate the water level height h1 of the water; use H - h to calculate the oil level height h2 at a single point; determine whether oil is being loaded or unloaded in the oil bladder at the current moment. If so, proceed to step S3; S3: Obtain the total volume of oil loaded or unloaded from the start of oil loading and unloading to the current moment, and calculate the change Δh in the oil liquid level height according to the tank volume curve of the oil bladder and the total volume of oil loaded or unloaded; the total volume of oil loaded or unloaded is obtained through the flow sensor; S4: Obtain the oil liquid level height d1 at the start of this oil loading and unloading, calculate the height value d2 through d1 + Δh, and take the average value of h2 and d2 as the optimized value of the oil liquid level height at a single point in the oil bladder at the current moment, then end.

2. The liquid level measurement method according to claim 1, characterized in that, The liquid level monitoring box further includes a control module and an alarm module. The control module is connected to the data processing module and the alarm module. When the liquid level height of water and / or the liquid level height of oil calculated by the data processing module exceeds the set threshold, the control module controls the alarm module to give an alarm.

3. The liquid level measurement method according to claim 2, characterized in that The alarm module is an audible and visual alarm.

4. The liquid level measurement method according to claim 1, characterized in that, The oil pipeline includes an oil injection pipeline and an oil discharge pipeline, and flow sensors are arranged on both the oil injection pipeline and the oil discharge pipeline.

5. The liquid level measurement method according to claim 1, characterized in that The water pipeline includes a water injection pipeline and a drainage pipeline, and flow sensors are arranged on both the water injection pipeline and the drainage pipeline.

6. The liquid level measurement method according to claim 1, characterized in that, The data processing module is further used to calculate the volume of water in the oil tank and the volume of oil in the oil bladder according to the liquid level height of water in the oil tank and the liquid level height of oil in the oil bladder.

7. The liquid level measurement method according to claim 1, characterized in that, In step S2, if it is judged that there is no oil loading and unloading in the oil bladder at the current moment, then enter step S5. S5: Advance the time t forward, where t is the time from the most recent stop of loading and unloading oil to the current moment, evenly divide the t period into n time points , and obtain the liquid level height of the oil corresponding to each time point at a single point ; S6: Calculate and obtain the corresponding and when it is the smallest. Take the average value of and as the optimized value of the oil liquid level height at the single point at the current moment.

8. The liquid level measurement method according to claim 7, characterized in that The method further includes calculating the volume of water and oil in a single oil tank based on the optimized value of the oil liquid level height at all single points and the liquid level height of water in the oil tank at the current moment. The specific steps are as follows: S7: Obtain the position information of each pressure sensor and ultrasonic sensor, the shape characteristics of the oil tank, and the attitude characteristics of the oil tank, and convert the measured liquid level height h1 of water and the optimized value of the oil liquid level height at each point into coordinate points; S8: Perform cubic spline interpolation based on the coordinate data of each point position, fit the interpolated points obtained by interpolation and each point position to obtain the water-air surface, oil-water surface, oil-air surface and oil-oil bladder surface, and at the same time obtain the water-air surface equation, oil-water surface equation, oil-air surface equation and oil-oil bladder surface equation; The water-air surface, oil-water surface and the inner wall of the cabin enclose to form the three-dimensional shape of water, and the oil-air surface and oil-oil bladder surface enclose to form the three-dimensional shape of oil; S9: Perform three-dimensional integration on the three-dimensional shape of oil to obtain the volume of oil in a single oil tank; Perform three-dimensional integration on the three-dimensional shape of water to obtain the volume of water in a single oil tank.

9. The liquid level measurement method according to claim 8, characterized in that, The method further includes calculating the total volume of oil in the current ship based on the volume of oil in a single oil tank, and the specific steps are as follows: S10: Determine whether oil is being loaded or unloaded at the current moment. If not, go to step S11; if so, go to step S12; S11: Obtain the volume of oil in each oil tank when the last oil loading or unloading stopped, sum up the volume of oil in each oil tank to obtain the total volume of oil in the ship V1 when the last oil loading or unloading stopped, calculate the total loss of oil volume ΔV1 of the ship from the last oil loading or unloading stop to the current moment according to the daily oil loss of the ship, then the total volume of oil in the ship at the current moment is V1 - ΔV1, and the calculation ends; S12: Obtain the volume of oil in each oil tank before the start of this oil loading or unloading, sum up the volume in each oil tank to obtain the total volume of oil in the ship V2 before the start of this oil loading or unloading; S13: Obtain the total amount of oil loaded ΔV2 and the total amount of oil unloaded ΔV3 from the start of oil loading or unloading to the current moment according to the flow data of the flow sensor; then the total volume of oil in the current ship is V2 + ΔV2 - ΔV3, and the calculation ends.

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