METHOD FOR MEASURING SLUDGE WITH INFRARED IN PETROLEUM STORAGE TANKS

Description

1 / 11 METHOD FOR MEASURING SLUDGE WITH INFRARED IN PETROLEUM STORAGE TANKS FIELD OF THE INVENTION

[01] The present invention falls within the technical field of petroleum storage and inventory control. More specifically, it relates to the storage of petroleum tanks and the analysis of sludge by means of infrared image capture and processing of the captured images. FUNDAMENTALS OF THE INVENTION

[02] The invention addresses the technical problem of sludge formation and accumulation in petroleum storage tanks. Sludge accumulation reduces tank storage capacity, interrupts operation, and can compromise the stored product. Furthermore, sludge formation and accumulation is a highly relevant phenomenon because it reduces tank storage capacity (useful volume), can interrupt operation, and cause the product to become unsuitable. Additionally, sludge typically has a high salinity and water content which, in permanent contact with the tank bottom, accelerates the consumption of sacrificial anodes, exposing the tank to a corrosive process.

[03] In this sense, the solution achieved by the invention is a non-intrusive sludge measurement method using infrared technology. This method allows quantifying the sludge accumulated in the tank without interrupting its operation, making it possible to monitor the sludge volume and carry out mitigating actions in a planned manner.

[04] This measurement is performed by collecting images of the storage tank at any time, without the need to stop, fill or drain it. Based on these images, it is possible to calculate the total volume of sludge deposited, allowing Petition 870250016176, dated 27 / 02 / 2025, pp. 44 / 61 2 / 11 thus better management of petroleum storage. As evidenced by the analysis of prior art documents, there is no similar method capable of achieving the same effect proposed by the present invention. STATE OF THE ART

[05] Document CN115752960A refers to a device for inspecting leak tightness and identifying leak points in vehicle fuel tanks. The device consists of a base plate, two fastening components, an air pump, a heating tank, a PC controller, a distribution box, an electronic pressure gauge, a solenoid valve, and an infrared camera. However, document CN115752960A is completely different from the technical objective of the present invention, insofar as it relates to inspecting leak tightness and identifying leak points in vehicle fuel tanks, while the initial invention mentioned relates to measuring the volume of sludge in petroleum storage tanks using an infrared camera and other equipment.

[06] Document WO2022200304A1 describes a solution for the visual and sensory inspection of closed storage tanks, citing the possibility of use in the petrochemical industry. This solution consists of a set of devices and methods that allow inspections to be carried out in closed tanks, even when they are pressurized and in potentially explosive environments. However, document WO2022200304A1 fails to describe a solution for measuring the volume of sludge in petroleum storage tanks, using a combination of infrared camera, laser tape measure, image processing software and interpolation algorithms. The present Petition 870250016176, dated 27 / 02 / 2025, pp. 45 / 61 3 / 11 invention, on the contrary, focuses specifically on the precise measurement of the tank sludge volume, using infrared technology and image processing to create a 3D representation of the sludge distribution inside the tank.

[07] The article entitled “SLUDGE INTERFACE MEASUREMENT IN THE STORAGE TANK UTILIZING NEUTRON BACKSCATTERING TECHNIQUE: A FIELD EXPERIMENT”, published in 2023, describes a sludge level inspection technique in crude oil storage tanks using the neutron backscattering technique. This technique involves the use of a neutron scanning system that includes a neutron emitter, a neutron detector, a rate counter, a winch for scanner movement, and a computer for data processing.While the present invention focuses on the use of technologies such as infrared cameras and laser measuring tapes for visual and sensory inspection of storage tanks, this article describes a different technique that uses neutron backscattering to detect the sludge level in crude oil storage tanks. This technique is more expensive and less feasible for large-scale application, as it also requires draining the oil tank.

[08] Document CN116543124A describes a method for identifying and evaluating sludge content in petroleum storage tanks based on images. It is considered the closest. However, document CN116543124A fails to present a suitable solution for very large tanks, yielding worse results when applied to the same scenario as the present invention. Furthermore, it does not stipulate a methodology for complete coverage of the evaluated tank surface in the document itself. In addition, there is no discussion in Petition 870250016176, dated 27 / 02 / 2025, pp. 46 / 61 4 / 11 document that assists in establishing parameters for the image capture steps and use of references for future processing, ensuring that the tank surface is faithfully depicted.

[09] Thus, unlike prior art documents, the present invention proposes a method for measuring sludge in large petroleum storage tanks. Specifically, the invention uses infrared through thermographic imaging of the tank shell to measure sludge levels below 1 meter in height, in tanks with a diameter greater than 75 meters. SUMMARY OF THE INVENTION

[010] The present invention relates to a method for measuring sludge in petroleum storage tanks using infrared technology, allowing the quantification of accumulated sludge without interrupting tank operation. The method involves capturing images of the tank interior and applying image processing algorithms to generate an accurate estimate of the sludge volume. BRIEF DESCRIPTION OF THE DRAWINGS

[011] The present invention will be described below with reference to typical embodiments thereof and also with reference to the attached drawings, in which:

[012] Figure 1 is a representation of thermographic images of the tank surface showing the temperature variations between the oil and the sludge, according to an embodiment of the present invention.

[013] Figure 2 is a representation of an inverted cylindrical panorama of the tank, stitched together from the images. Petition 870250016176, dated 27 / 02 / 2025, pp. 47 / 61 5 / 11 thermal values ​​acquired, according to one embodiment of the present invention.

[014] Figure 3 is a representation of a three-dimensional cylinder of the sludge distribution within the tank, projected from the marked sludge points, according to an embodiment of the present invention.

[015] Figure 4 is a planar representation of the three-dimensional cylinder, indicating the sludge accumulation regions, according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[016] The method for measuring sludge in petroleum storage tanks, as described in this invention, involves the use of a combination of infrared cameras, laser measuring tapes and image processing software to measure, calculate and monitor the volume of sludge without the need to interrupt tank operations.

[017] The process begins with the installation of infrared cameras and laser measuring tapes in the storage tank. Infrared cameras are positioned at strategic points around the tank, typically on the sides and top of the tank, to capture a wide view of the internal surface. Depending on the size of the tank, it may be necessary to install several cameras to cover the entire area. Laser measuring tapes are placed at predetermined measurement points to ensure accurate data collection on the sludge height in various parts of the tank.

[018] Infrared cameras are calibrated to detect temperature differences between stored oil and sludge, since both have distinct thermal properties. Sludge, composed of sedimentary particles, water Petition 870250016176, dated 27 / 02 / 2025, pp. 48 / 61 6 / 11 and residual oil exhibit a different thermal signature than more fluid petroleum, which facilitates its visual detection in captured images. Laser measuring tapes, on the other hand, are configured to perform distance and height measurements of the sludge relative to the bottom of the tank.

[019] With the equipment installed and calibrated, the data capture phase begins. Infrared cameras perform periodic scans of the tank, recording thermographic images of the surface, as can be seen in figure 1. These images clearly show the temperature variations between the oil and the sludge 12, in relation to the markers 10, facilitating the identification of areas where sediment accumulates.

[020] Simultaneously, laser measuring devices perform three-dimensional measurements of the sludge surface. They fire laser pulses towards the bottom of the tank and measure the time it takes for the beam to return, thus calculating the height of the sedimented material. This process is repeated at different points in the tank, generating a three-dimensional map of the sludge distribution.

[021] Infrared images and laser measurements are sent to image processing software. This software is responsible for analyzing and processing the collected images and data, identifying regions where sludge has accumulated. The thermographic images captured by the cameras are automatically segmented by the software, which distinguishes the sludge areas based on the temperature difference relative to the surrounding oil.

[022] The software uses advanced image processing algorithms to generate a three-dimensional representation of the sludge inside the tank. This visualization Petition 870250016176, dated 27 / 02 / 2025, pp. 49 / 61 7 / 11 allows operators to clearly understand the distribution and volume of accumulated sludge in each region. Laser measurements are integrated with image data to increase the accuracy of volumetric estimation, providing additional data on sludge thickness at specific points.

[023] In addition, the software uses interpolation algorithms to calculate the total volume of sludge in the tank. These interpolations are especially useful for estimating the volume of sludge in areas where the visibility of infrared cameras may be limited, or where laser measurements cannot directly cover. The software combines this data to ensure an accurate and comprehensive measurement.

[024] Once the data is processed, the software generates detailed reports that include a three-dimensional graphical representation of the sludge in the tank, as well as numerical estimates of the total volume. These reports are stored in a management system, where they can be analyzed by operators to plan corrective actions, such as sludge removal or preventive maintenance.

[025] The method allows monitoring to be carried out continuously or periodically, according to operational needs. Infrared cameras can be programmed to perform automatic scans at regular intervals, while laser measuring tapes continue to measure the sludge height at pre-established points. This ensures that any unexpected sludge buildup is detected quickly, allowing necessary measures to be taken before it compromises tank operation. Petition 870250016176, dated 27 / 02 / 2025, pages 50 / 61 8 / 11

[026] More specifically, the present invention proposes a method for measuring sludge with infrared radiation in petroleum storage tanks comprising: Mounting a laser measuring tape and an infrared camera on a tripod; the positioning of a metal plate of the support on the tripod; The placement of markers on the tank's side to serve as a measurement reference; The configuration of the infrared camera, adjusting parameters such as apparent reflected temperature, emissivity, acquisition distance, and dynamic temperature range; The acquisition of thermal images of the tank's shell along a circular path around the tank; the processing of the acquired images; The generation of a three-dimensional representation of the sludge distribution inside the tank; and the calculation of the sludge volume.

[027] The infrared camera configuration includes adjusting the ambient temperature and relative humidity; setting the apparent reflected temperature to 90% of the ambient temperature; setting an emissivity of 0.95; setting the image acquisition distance between 10 and 15 meters from the tank; adjusting the dynamic temperature range for image acquisition; and setting it for single-shot image acquisition (one image per trigger).

[028] In addition, markers are positioned on the tank side, where the first marker is positioned to the right of the tank's product inlet / outlet piping; the markers are placed below a black stripe on the side and at a distance that allows only two markers to be seen. Petition 870250016176, dated 27 / 02 / 2025, pages 51 / 61 9 / 11 per image; and the markers are not moved during image acquisition to ensure correlation between them.

[029] In this sense, the distance between two subsequent markers follows the following relationship: distance FOV x DST x (1 - OVP) x (2 DST+DIA / DiA) x DIA\ (2 DST + DIA) where DST represents the distance between the camera and the tank, DIA represents the diameter of the tank, FOV represents the camera's field of view, and OVP represents the overlap between the images.

[030] The thermal image acquisition stage is performed continuously, in a counter-clockwise direction around the tank, until the marker of the first image is registered again, completing a full circle around the tank. The distance between the camera and the tank is kept constant using the laser tape measure, ensuring a 30% overlap between adjacent images.

[031] The thermal image processing stage involves stitching the images into an inverted cylindrical panorama, as shown in Figure 2. Next, the stage of generating a three-dimensional representation of the sludge distribution inside the tank involves unrolling the inverted cylindrical panorama into a long rectangular image; marking the fractions corresponding to the sludge as sludge points; and projecting the sludge points onto a 3D cylinder, as shown in Figure 3. The interior of the cylinder is reconstructed using the kriging technique to interpolate the points within the tank. In addition, a plan view of the cylinder is provided, indicating regions of sludge accumulation, as shown in Figure 4. Petition 870250016176, dated 27 / 02 / 2025, pages 52 / 61 10 / 11

[032] This type of monitoring can be easily integrated into inventory management systems or quality control platforms used by the storage facility. This allows sludge data to be cross-referenced with information on the volume of oil stored, product quality, and tank operating history. In this way, operators can more accurately predict when sludge will reach critical levels, allowing for the planning of interventions before the buildup affects the tank's usable capacity.

[033] The proposed method has the advantage of being non-intrusive, eliminating the need to stop the tank or drain the oil to perform the measurements. By monitoring the sludge in real time and without interrupting operations, the invention offers an efficient and economical way to maximize storage capacity and minimize operating costs associated with cleaning and maintenance.

[034] The method was developed to be applicable to large tanks, such as those found in refineries and storage terminals, which can have diameters exceeding 75 meters. The ability to accurately monitor sludge in large tanks represents a significant advance over conventional techniques, which often fail to fully cover these extensive areas. With the present invention, precise measurement of sludge in large tanks is possible, providing comprehensive monitoring of the integrity of the tank and its contents.

[035] In summary, the method described is capable of providing an accurate and efficient measurement of sludge accumulated in oil storage tanks. By combining infrared cameras, Petition 870250016176, dated 27 / 02 / 2025, pp. 53 / 61 Using 11 / 11 laser measuring tapes and advanced image processing, the method offers a solution for waste management, optimizing tank usage and ensuring continuity of operations without unnecessary interruptions. Petition 870250016176, dated 27 / 02 / 2025, pp. 54 / 61

Claims

1 / 3 CLAIMS 1. Infrared method for measuring sludge in petroleum storage tanks, characterized in that it comprises: mounting a laser tape measure and an infrared camera on a tripod; positioning a metal support plate on the tripod; positioning markers on the tank wall to serve as a measurement reference; setting up the infrared camera; acquiring thermal images of the tank wall along a circular path around the tank; processing the acquired images; generating a three-dimensional representation of the sludge distribution inside the tank; and calculating the sludge volume.

2. Method, according to claim 1, characterized in that the infrared camera configuration includes: adjustment of ambient temperature and relative humidity; setting the apparent reflected temperature to 90% of the ambient temperature; defining an emissivity range; setting the image acquisition distance between 10 and 15 meters from the tank; adjusting the dynamic temperature range for image acquisition; setting for single-shot image acquisition (one image per actuation); adjusting the camera focus to ensure image sharpness of the tank side; Petition 870250016176, dated 27 / 02 / 2025, page 55 / 61 2 / 3 defining the minimum thermal sensitivity of 0.04°C in the temperature range of 0 to 40°C; and defining the minimum camera resolution of 640x480 pixels.

3. Method, according to claim 1, characterized in that the markers are positioned on the tank wall, wherein: the first marker is positioned to the right of the tank's product inlet / outlet pipe; the markers are placed below a black strip on the wall; and the markers are not moved during image acquisition to ensure correlation between them.

4. Method, according to claim 1, characterized in that the distance between two subsequent markers follows the relationship distance FOV X DST X (1 - OVP) X (2 DST + D1A / dí^ X DIA\ (2 DST + DIA) wherein: DST represents the distance between the camera and the tank; DIA represents the diameter of the tank; FOV represents the field of view of the camera; and OVP represents the overlap between the images.

5. Method, according to claim 1, characterized in that the thermal image acquisition step is performed continuously, in a counter-clockwise direction around the tank, until the marker of the first image is registered again, completing a full turn around the tank.

6. Method, according to claim 1, characterized in that the distance between the camera and the tank is kept constant using a laser measuring tape. Petition 870250016176, dated 27 / 02 / 2025, pp. 56 / 61 3 / 3 7. Method, according to claim 1, characterized in that the thermal image processing step comprises stitching the images into an inverted cylindrical panorama.

8. Method, according to claim 1, characterized in that the step of generating a three-dimensional representation of the sludge distribution inside the tank comprises: unrolling the inverted cylindrical panorama into a long rectangular image; demarcating the fractions corresponding to the sludge at sludge points; and projecting the sludge points onto a 3D cylinder.

9. Method, according to claim 8, characterized in that the interior of the cylinder is reconstructed using the kriging technique to interpolate the points inside the tank.

10. Method according to claim 1, characterized in that the sludge measurement can be performed while the tank is in operation. Petition 870250016176, dated 27 / 02 / 2025, pp. 57 / 61

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