Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
  • G01M3/22—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material for pipes, cables or tubes; for pipe joints or seals; for valves; for welds; for containers, e.g. radiators
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
  • F17D5/00—Protection or supervision of installations
  • F17D5/02—Preventing, monitoring, or locating loss
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
  • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
  • F17D5/00—Protection or supervision of installations
  • F17D5/005—Protection or supervision of installations of gas pipelines, e.g. alarm
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/16—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using electric detection means
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M3/00—Investigating fluid-tightness of structures
  • G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
  • G01M3/04—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point
  • G01M3/20—Investigating fluid-tightness of structures by using fluid or vacuum by detecting the presence of fluid at the leakage point using special tracer materials, e.g. dye, fluorescent material, radioactive material
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
  • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
  • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
  • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
  • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
  • G01N21/314—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry with comparison of measurements at specific and non-specific wavelengths
  • G01N2021/3155—Measuring in two spectral ranges, e.g. UV and visible

Definitions

• the present invention generally relates to the field of monitoring gas leaks and/or monitoring sources emitting particles, more particularly the monitoring of leaks of a gas supplying or intended to supply gas distribution networks, such as natural gas or biomethane.
• Leaks of natural gas or biomethane can occur in a non-limiting way at the level of storage sites for these gases (for example geological reservoirs or tanks), at the level of installations for the transport of gas (for example pipes at high pressure for transporting gas over long distances), at the level of gas distribution facilities (for example injection stations in the distribution network, pipes allowing local distribution to different entities, individuals, companies, etc.), or at the level of installations using these gases (for example gas-fired power stations, certain chemical and petrochemical industries, homes for domestic use, etc.).
• these gases for example geological reservoirs or tanks
• the level of installations for the transport of gas for example pipes at high pressure for transporting gas over long distances
• gas distribution facilities for example injection stations in the distribution network, pipes allowing local distribution to different entities, individuals, companies, etc.
• these gases for example gas-fired power stations, certain chemical and petrochemical industries, homes for domestic use, etc.
• Biomethane results from the purification of a biogas, which is produced by the anaerobic decomposition of waste of organic origin, such as sludge from treatment plants, agricultural waste, landfills.
• Biogas is mainly composed of methane (40 to 70%), CO2 and water vapour, but it also contains impurities, such as sulfur compounds (H2S, SO2, ...), siloxanes, halogens or even VOCs (Volatile Organic Compounds). Biogas is therefore not directly usable. To be able to exploit biogas, it must be purified (or even purified), in particular to eliminate carbon dioxide and hydrogen sulphide, but also other impurities.
• Biomethane is thus obtained which can be injected into a distribution network, which is generally the natural gas distribution network.
• Natural gas is odorless, highly explosive (5-15% in air) and deadly when inhaled in high concentrations. To detect any leaks and avoid any risk of explosion, the natural gas is artificially odorized before being injected into the transmission network. The same is true for biomethane. This makes it possible to differentiate whether the gas emanations result from a leak, in order in particular to trigger an alert, or to detect whether they are natural emanations.
• the odorous molecules used are historically mercaptans such as ethane mercaptan (also called ethanethiol or ethyl mercaptan), methane mercaptan (also called methanethiol or methyl mercaptan).
• ethane mercaptan also called ethanethiol or ethyl mercaptan
• methane mercaptan also called methanethiol or methyl mercaptan
• THT tetrahydrothiophene molecule
• THT is a colorless, flammable liquid with a characteristic sulfur odor (it is an organic sulfur compound).
• the odorous products are injected in very small quantities (approximately 10 ppb) into the gas to be odorised.
• chemistry-transport models make it possible to describe the evolution of atmospheric pollutants or particles (aerosols, gases, dust) released into the atmosphere. This evolution is due to the transport by the wind of pollutants (particles, gas molecules) in the atmosphere and to the chemical reactions in which the pollutants take part.
• the chemistry-transport models make it possible in particular to simulate the quality of the air or to simulate a continuous release of particles.
• the methods used to determine a gas leak point following its release into the atmosphere at a given flow rate are based on solving an inverse problem.
• a description of these methods can be found in the documents (Klein et al., 2016; Kumar et al., 2021 ) More precisely, for this inverse problem, we consider a spatial region of the site studied in which we sense that the point leak is located. Then we subdivide this region using a Cartesian grid composed of cells. Each node of the mesh is then considered as a potential vanishing point.
• the inverse problem consists in searching iteratively for the source flow rate at each node of the mesh, making it possible to best explain (or even satisfy) (for example in the sense of least squares) the concentration measurements.
• the present invention overcomes these drawbacks. More specifically, the present invention relates to a method implemented from concentration measurements carried out by a mobile monitoring station, the method being very inexpensive in terms of calculation time and memory, and making it possible to determine reliably and almost in real time, the location of the origin of a gas and/or particle leak. Moreover, the method according to the invention does not require pre-supposition of a location of the emitting source. Summary of the invention
• the invention relates to a method for determining the position of a source emitting at least one gaseous compound and/or particles in a geographical area, by means of a mobile measurement system comprising at least one sensor for measuring a concentration into said gaseous compound and/or into said particles and a sensor for measuring wind speed and direction.
• the method according to the invention comprises at least the following steps: a) measuring said concentration of said gaseous compound and/or of said particles, said speed and said direction of the wind for a succession of positions of said mobile measuring system forming a trajectory moving said mobile measuring system in said geographical area, each of said positions corresponding to a measurement time of said mobile measuring system, said positions of said succession of positions of said mobile measuring system positions being determined so that each of the segments between two consecutive positions of said succession of positions of said mobile measuring system forms an angle of between 45° and 135° with an instantaneous or mean wind direction coming from said measured wind direction, and a first curve representative of the evolution of said concentration for each of said gaseous compounds and/or for said particles as a function of the measurement time of said mobile measuring system, and of the second and third curves representing respectively the evolution of the speed and the direction of the wind as a function the measurement time of said mobile measurement system; b) on the basis of predefined criteria, for each of said first curves, at least one pair formed by a consecutive minimum and maximum of said first
• said position x 0 of said source emitting a gaseous compound or particles can be determined according to a formula of the type: where NE is the number of said determined pairs, x ne is the said position of said mobile measuring system along said trajectory corresponding to said maximum of said pair ne , ne is the time difference between said maximum and minimum of said pair ne, and v ⁇ e is a vector oriented along said mean wind direction between said measurement times of said mobile measurement system corresponding to said minimum and maximum of said torque ne and whose norm is said mean wind speed between said measurement times of said corresponding mobile measurement system to said minimum and maximum of said torque ne.
• the angle formed between said segment between said first and second positions of said pair of consecutive positions of said trajectory and said wind direction measured for said first position of said pair or said average wind direction measured prior to step a) can be between 80° and 100°, and is preferably 90°.
• a Butterworth filter can be applied to at least one of the first and/or second and/or third curves and steps b) can be applied and/or c) from said first and/or second and/or third filtered curves.
• said predefined criteria of said first curve can be formed from a first and a second threshold value Slext and S2ext defined according to formulas of the type:
• steps ii) and iii) are repeated by continuing the course of said N samples of said curve to determine the set of NI pairs (nmin(i), nmax(i)) formed of said indices nmin(i) and nmax(i ) samples corresponding to a minimum and a maximum of said first curve, with i varying from 1 to NI.
• the invention relates to a computer program product downloadable from a communication network and/or recorded on a computer-readable medium and/or executable by a processor, comprising program code instructions for at least implementation of steps b) and c) described above, when said program is executed on a computer.
• FIG. 1 presents the geographical positions of a mobile measurement system moving along a path of movement for an example of application of the method according to the invention.
• Figure 2A shows the evolution of a measured methane concentration as a function of time along the displacement trajectory of the mobile measuring system shown in Figure 1.
• Figure 2B shows the evolution of a measured wind direction as a function of time along the travel path of the mobile measurement system shown in Figure 1.
• Figure 2C presents the evolution of a measured wind speed as a function of time along the displacement trajectory of the mobile measurement system presented in Figure 1.
• FIG. 3 highlights the minima of the curve of FIG. 2A determined by means of the method according to the invention, each minimum being followed by a maximum.
• Figure 4 shows a portion of Figure 4, including at least a minimum followed by a maximum.
• Figure 5 corresponds to Figure 1, in which the position of the source of the gas leak is also shown, determined by means of the method according to the invention, as well as the actual position of the source emitting the gas.
• the present invention relates to a method for determining the position of a source emitting at least one gaseous compound and/or particles in a geographical area.
• the method according to the invention aims to determine the position of the origin of a gas or particle leak in a geographical area.
• the position of the source emitting a gaseous compound and/or particles, result of the method according to the invention can be in two or in three dimensions.
• the geographic area of interest may, for example, include a portion of an industrial site that generates gaseous and/or particulate pollutants.
• the gaseous compound can be a gaseous hydrocarbon compound such as methane, ethane, butane, but the gaseous compound can also be carbon monoxide, carbon dioxide, hydrogen, or even a gaseous compound used to odorize gases such as tetrahydrothiophene (also denoted THT) or a mercaptan (for example ethanemercaptan or methanemercaptan).
• THT tetrahydrothiophene
• mercaptan for example ethanemercaptan or methanemercaptan.
• particles any solid or liquid body with a dimension of less than 100 ⁇ m, optionally with a volatile phase which can be adsorbed on a solid phase.
• the particles according to the invention may correspond to soot particles which are fine particles (micrometric, submicron and nanometric) rich in PAHs (polycyclic aromatic hydrocarbons), but also particles resulting from the abrasion of parts such as by example metal particles from brake pads, particles from tire abrasion, but also pollen, etc.
• PAHs polycyclic aromatic hydrocarbons
• the particles according to the invention are transported by the ambient air.
• the method according to the invention is implemented by means of a mobile measuring system comprising a sensor for measuring at least one concentration of at least one gaseous compound and/or of particles whose origin it is desired to locate, as well as a sensor for measuring wind speed and direction.
• mobile measurement system is meant a measurement system capable of being moved, the system itself comprising means of movement, or else the system being on board a vehicle, such as a motor vehicle, a truck, a motorized two-wheeler, or even a drone, an airplane, etc.
• the mobile measurement system implemented for the method according to the invention comprises a single sensor for measuring the concentration of a plurality of gaseous compounds.
• a single sensor is for example described in patent application EP3901604.
• the system described in this application comprises an optical measurement system comprising at least:
• At least one light source for emitting UV radiation and IR radiation through the ambient air in a measurement zone
• spectrometer capable of detecting at least part of the UV radiation having passed through the ambient air in the measurement zone and of generating a digital signal of the light intensity as a function of the wavelength of the part of the UV radiation;
• an IR detector capable of detecting at least part of the IR radiation having passed through the ambient air in the measurement zone, and of generating a digital signal of the light intensity as a function of the wavelength of the part of the radiation IR.
• system described in this application further comprises means for processing and analyzing the digital signal or signals (for example by computer means using a microprocessor) to detect and/or characterize a leak of gas from the digital signal or signals according to a method described in this application.
• the method described in patent application EP3901604 is as follows: from the emission by a light source of UV radiation and IR radiation and by means of a UV spectrometer and a detector IR, a digital signal of the light intensity is generated as a function of the wavelength, and at least the concentrations of methane and of the odorous chemical species are estimated from at least the digital signal.
• We detect and we characterizes a gas leak by at least one comparison of the methane concentration with a first threshold and one comparison of the concentration of the odorous chemical species with a second threshold.
• Such a system and such a process make it possible to quantify in the ambient air, simultaneously, and in real time, all the adsorbent gas molecules in the ultraviolet and in the infrared.
• such a measurement system and such a method are suitable for measuring a concentration of methane and of THT.
• the sensor for measuring wind speed and direction may be a weather station.
• the senor for measuring a particle concentration can be the sensor described in document WO2021/170413 A1.
• the method according to the invention comprises at least steps 1 to 3 described below, step 4 being optional.
• the concentration of at least one gaseous compound and/or of particles is measured, as well as the speed and the direction of the wind for a succession of positions of the mobile measurement system forming a displacement trajectory of the mobile measurement system in the geographical area.
• the method according to the invention does not require that the trajectory along which the measurements are carried out pass through the position of the source emitting the gaseous compound and/or the particles.
• the trajectory according to the invention must cross at least once the plume generated by the source emitting the gaseous compound and/or the particles of interest.
• the trajectory according to the invention can cross the plume generated by the source emitting the gaseous compound and/or the particles of interest several times, in order to be able to benefit from a redundancy of information relating to the position of the emitting source, as will be discussed in step 3) below.
• a concentration measurement can be carried out for a plurality of gaseous compounds and/or for a plurality of particles.
• the succession of positions of the mobile measurement system is determined so that each of the segments between two consecutive positions of the succession of positions of the mobile measurement system forms an angle comprised between 45° and 135° with a instantaneous or mean wind direction from said measured wind direction.
• the succession of positions of the mobile measurement system is determined so that, for each pair of consecutive positions comprising a first and a second position, a segment between the first and second positions of the pair considered forms an angle between 45° and 135:
• the trajectory of the mobile measurement system is determined in real time, according to the direction of the wind measured at each position and in order to determine the next position of the mobile measurement system. This is called instantaneous wind direction.
• the trajectory of the mobile measurement system is determined from a prior measurement of the average direction of the wind, a measurement which can be carried out prior to the implementation of step a), or well during the implementation of step a), for example on a plurality of consecutive positions of the mobile measurement system prior to the second position.
• the mobile measuring system implemented for the method according to the invention moves along a trajectory whose segments between two consecutive positions form an angle of between 45° and 135° with a direction of the wind (instantaneous or average).
• a trajectory makes it possible to consider that the measurement curve over time of the concentrations of gaseous compound and/or particles is of Gaussian form (if the plume of gas or particles is crossed once) or is formed of a plurality Gaussian-shaped curves (if the plume of gas or particles is crossed several times).
• the measurement curve of a concentration of gaseous compound or of particles is of general Gaussian form when one deviates up to 45° with respect to the direction perpendicular to the wind.
• the mobile measuring system implemented for the method according to the invention moves along a trajectory whose segments between two consecutive positions form an angle of between 80° and 100°, preferably 90°, with the wind direction (instantaneous or average). The assumption that the shape of the measurement curves of a gaseous compound or particle concentration is of the Gaussian type is thus all the more valid.
• trajectory according to the invention can be of any geometry, as long as the constraint with respect to the direction of the wind stated above is verified.
• the trajectory can in particular have a complex geometry if, at least in the first case stated below, the direction of the wind is particularly changing during step a).
• a measurement of the concentration of at least one gaseous compound and/or of particles of interest is carried out for the succession of consecutive positions of the mobile measurement system thus determined. It is quite clear that to any position of the mobile measuring system corresponds a measuring time (i.e. an instant of measurement) of the mobile measuring system, the mobile measuring system moving during the measurement. It is quite clear that the speed of movement of the mobile measurement system can be variable, and even zero, during the implementation of this step. Preferably, the measurements can be time-stamped during this step, in order to know the measurement time corresponding to a measurement position of the mobile measurement system.
• a discrete function x(t) associating with any measurement time of the mobile measurement system a position of the mobile measurement system. It is quite clear that this function is not necessarily bijective insofar as the same position of the mobile measurement system can correspond to several measurement times of the mobile measurement system when the trajectory of the mobile measurement system includes several passages through the same spatial position. Such repetition of the measurement at the same position can be advantageous to improve the redundancy of information, even if the direction of the wind has changed between the different passages of the mobile measurement system by the same measurement point.
• the succession of positions of the mobile measurement system as a function of an instantaneous or average direction of the wind, but also as a function of a speed of movement of the mobile system and of a measurement frequency of the mobile measurement system.
• the line segments on which the positions of the measurement points must be located are determined according to an instantaneous or average direction of the wind, but the positions on these segments are determined according to a measurement frequency and d 'a displacement speed of the measurement system mobile.
• the speed of movement of the mobile measurement system can be between 10 and 90 km/h, and is preferably 30 km/h.
• the measurement frequency of the mobile measurement system can be between 0.5s and 5s, and is preferably 1 s.
• Such displacement speed values of the mobile measurement system preferably combined with such measurement frequency values, allow sufficient sampling of the curves resulting from these measurements.
• a filter in order to reduce the measurement noise present on at least one of the curves thus measured, a filter can be applied to said curve, for example a low-pass filter of the IIR (Infinite Impulse Response) type, in particular a Butterworth filter.
• IIR Infinite Impulse Response
• Such filters make it possible to eliminate high frequency oscillations while preserving the slowly varying parts of the signal, or in other words such filters make it possible to smooth the curves.
• a concentration measurement has been carried out for a plurality of gaseous compounds and/or for a plurality of particles, it is possible to obtain a plurality of curves representative of the evolution of the concentration of a gaseous compound or of particles as a function of the measuring time of the mobile measuring system. Subsequently and for the purpose of simplifying the reading, we can speak of "concentration curve” instead of "curve representative of the evolution of the concentration of a gaseous compound or of particles as a function of the measurement time of the system mobile measurement”.
• the set of pairs formed by a minimum (local or global) and a maximum (local or global) consecutive (i.e. which follow each other along the along a curve) in each of the curves representative of the revolution of the concentration of a gaseous compound or of particles as a function of the measurement time of the mobile measurement system.
• a minimum local or global
• a maximum local or global
• Such a search can be carried out by means of any search algorithm for extrema in a curve.
• a person skilled in the art knows a plurality of algorithms for searching for extrema in a curve.
• this step it is possible to determine a plurality of pairs formed of a minimum followed by a consecutive maximum of the concentration curve considered, in order to improve the redundancy of information as will be discussed in the step 3) below. It is quite clear that one can determine a plurality of pairs formed by a minimum followed by a consecutive maximum in a concentration curve only on condition that the trajectory defined in the previous step crosses the plume several times. gases and/or particles.
• this step is applied to each of the concentration curves of a gaseous compound or of particles as a function of the measurement time of the mobile measurement system.
• at least one of the curves of concentration in a gaseous compound or in particles can be filtered prior to the application of this step, and the determination of at least a couple formed of a minimum followed by a consecutive maximum for this concentration curve can be made on the filtered curve.
• the predefined criteria can comprise at least one threshold value depending on the measurement error of the measurement system, preferably equal to ten times the measurement error of the measurement system.
• This threshold value denoted Serr thereafter, can then be advantageously used in order to overcome errors in the measurement during the search for the extrema of the concentration curve considered.
• the predefined criteria can be formed from two threshold values depending on the values of the global minimum (denoted Cmin below) and maximum (denoted Cmax below) of the concentration curve considered.
• the first and second thresholds denoted S1 ext and S2ext hereafter, are defined as a function of the value of the global minimum and maximum of the concentration curve considered according to formulas of the type:
• an index corresponding to a minimum of the concentration curve is sought, this minimum being chosen taking into account a maximum slope, a function of the second threshold S2ext as defined above, between the minimum and the measurement according to this minimum in the concentration curve.
• steps ii) and iii) are repeated by continuing the course of the N samples of the concentration curve to determine the set of NI pairs (nmin(i), nmax(i)) formed of the indices nmin and nmax of the samples corresponding at a minimum and at a maximum of the concentration curve considered.
• NE pairs formed by a consecutive minimum followed by a maximum of a given concentration curve are kept for which C(nmax(i)) > Cmin + 0.05 * (Cmax - Cmin) with i varying from 1 to NI, i.e. only the pairs exhibiting a maximum of sufficiently large amplitude to be used reliably for the determination of the position of the transmitting source.
• NE the number of pairs formed of a minimum followed by a consecutive maximum determined for a given concentration curve, NE equaling the maximum NI.
• the position of the mobile measuring system corresponding to the maximum of the torque considered is determined, as well as a deviation time between the measurement time of the mobile measurement system corresponding to the maximum of the torque considered and the measurement time of the mobile measurement system corresponding to the minimum of the torque considered.
• x ne the position of the mobile measuring system corresponding to the maximum of the pair considered, and A ne l time difference between the maximum and the minimum preceding the maximum of the torque considered ne.
• x ne x(t ⁇ x )
• t ⁇ x the measurement time of the mobile system corresponding to the maximum of the torque considered ne
• x(t) the discrete function associating to any measurement time of the mobile measurement system a position of the mobile measurement system described in the previous step.
• the position of the source emitting the gaseous compound and/or the particles considered is determined from the positions of the mobile measurement system corresponding to the maxima of the NE pairs formed d a consecutive minimum and maximum and the time differences between the maximum and minimum of the NE pairs determined in the previous step for the gaseous compound or the particles considered, as well as average wind speeds and directions between the measurement times of the mobile measuring system corresponding to the minimum and maximum of the NE pairs.
• a position of the source emitting each gaseous compound and/or particles measured is determined. Indeed, in the same geographical area, there may be several sources emitting different or same gaseous compounds and/or particles.
• At least the wind direction curve or the wind speed curve has been filtered prior to the application of this step, and the determination of the average direction and speed between the times corresponding to the minimum and maximum of the NE pairs is carried out on the filtered curve(s).
• NE is the number of pairs formed of a consecutive minimum and maximum
• x ne is the position of the mobile measuring system corresponding to the maximum of the torque ne
• ⁇ ne is the time difference between the maximum and minimum of the torque ne
• v ⁇ e is a vector oriented according to the mean direction of the wind between the measurement times of the mobile measurement system corresponding to the minimum and maximum of the torque ne and whose norm is the mean wind speed between the measurement times of the mobile measurement system corresponding to the minimum and maximum of the torque ne.
• the position of the emitting source of the gaseous compound or of the particles considered can be determined from an average of intermediate positions x 0 ,ne determined for each pair ne according to a formula of the type: 0 ,ne ⁇ ( ne ⁇ ⁇ -ne ⁇ ne) ( )-
• an intermediate position for a given torque ne can be obtained by a translation of the position of the mobile measurement system corresponding to the maximum of the torque ne, this translation being a function of the average of the speed vector over the time interval between the torque minimum and maximum, as well as the time for the mobile measurement system to cross the plume until it reaches the measurement point corresponding to a maximum concentration.
• the plurality of intermediate positions allows redundancy of information relating to the position of the source emitting the gaseous compound and/or the particles, and that the average of the intermediate positions makes it possible to attenuate the impact of the errors linked measurements (of concentration, direction and wind speed) as well as the impact of errors related to the assumptions leading to equation (2) above relating to intermediate positions.
• the main assumptions leading to equation (2) above are as follows: the wind is invariant in direction and speed over the time interval between the minimum and maximum of a couple (stationarity assumption) the measurement is made perpendicular to the main wind direction.
• a position of the emitting source of each gaseous compound and/or particles measured in step 1 is obtained. It is quite clear that in the majority of cases, the positions determined for each compound/particle will be close to each other. According to one implementation of the invention, if the relative difference between source positions determined for two different gaseous compounds and/or particles is less than 5%, then it can be considered that it is the same source emitter for the two gaseous compounds and/or particles. The position of the source of these two gaseous compounds can then be obtained by taking the average of the two positions. Otherwise, they are considered to be two different sources.
• the additional characteristic relating to the emitting source of at least one gaseous compound and/or of particles is the diffusion coefficient
• the additional characteristic relating to the source emitting at least one gaseous compound and/or particles is the flow rate of the emitting source
• the flow rate relating to the emitting source of a gaseous compound or particles denoted Q o below, according to a formula of the type: where C max and C min are respectively the global maximum and minimum of the concentration curve.
• the position of the emitting source can be determined in real time at least one gaseous compound and/or particles, as the mobile measurement system moves. More specifically, for each position of the mobile measurement system in step 1), we seek to determine a pair formed by a consecutive minimum and maximum in the curve measured up to the current position of the mobile measurement system , and if a torque is determined, the position of the source emitting at least one gaseous compound and/or particles is determined from torque and from any torque determined for previous positions of the mobile measurement system.
• the method according to the invention comprises steps implemented by means of equipment (for example a computer workstation) comprising data processing means (a processor) and data storage means (a memory, in particular a hard disk), as well as an input and output interface for entering data and restoring the results of the method.
• equipment for example a computer workstation
• data processing means a processor
• data storage means a memory, in particular a hard disk
• the data processing means are configured to at least perform steps 2) and 3) described above, as well as optional step 4).
• the invention relates to a computer program product downloadable from a communication network and/or recorded on a computer-readable medium and/or executable by a processor, comprising program code instructions for at least implementation of steps 2) and 3) and optionally 4) described above, when said program is executed on a computer.
• the method according to the invention was implemented to locate the source of a natural gas leak in a geographical area located near a geological gas storage site.
• the source emitting gas has a known position since it is a leak from a gas tank.
• Step 1 of the method according to the invention was implemented by means of an embodiment of the system and the method described in patent application EP3901604, in order to measure the concentration of methane, ethane, carbon dioxide and in THT (odorant molecule, added to methane for safety reasons) present in the ambient air.
• the measurement system described in this application was embedded in a vehicle, the UV and IR sensors as well as the light source being placed on the roof of the vehicle, the means for processing and the analysis of the digital signals coming from these sensors being arranged inside the car.
• Figure 2A shows the evolution of the methane C-CH4 concentration measured as a function of time T along the trajectory of the mobile measuring system shown in Figure 1. It can be observed that this curve comprises a plurality of concentration peaks, which testify to the fact that the trajectory of the mobile measurement system comprises several passages through the gas plume.
• Figure 2B and Figure 2C respectively present the curves of the evolution of the direction DIR of the wind compared to and the speed of the wind VIT measured according to the time T along the trajectory of the mobile measurement system presented in Figure 1 It can be observed that the direction of the wind can be particularly changing during the measurement.
• step 2 of the method according to the invention led to the identification of 15 pairs formed of a consecutive minimum and maximum according to the invention, comprised between a minimum and a maximum.
• Figure 3 presents the C-CH4 curve of CH4 concentration of Figure 2A, on which the vertical lines correspond to the 15 minima identified, each minima being followed by a maximum of the C-CH4 curve of CH4 concentration.
• FIG. 4 shows an enlargement of a portion of FIG. 4 comprising a pair formed by a consecutive minimum and maximum, and shows the time difference TNE between the maximum (at time TMAX) and the minimum (at time TMIN) preceding the maximum of this torque.
• FIG. 5 repeats FIG.
• the vanishing point determined by means of the method according to the invention has UTM coordinates (-71535.843, 5375049.606) whereas the real vanishing point has UTM coordinates (-71533.905, 5375047.433).
• the error in the position of the source emitting the gas of the method according to the invention is only 2.9 m.
• this result was obtained in less than 2 hundredths of a second on an Intel(R) Xeon(R) CPU E5-1620 v3 @ 3.50GHz type processor.
• the method according to the invention therefore allows an accurate and reliable determination of the position of a source emitting a gas in a geographical area.
• the method according to the invention is also faster and simpler to implement than the methods according to the prior art, because it does not require complex calculations such as the resolution of an inverse problem, very time-consuming calculation and in memory.
• it is possible to implement the method according to the invention in an on-board manner and in real time.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Sampling And Sample Adjustment (AREA)
• Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
• Investigating Or Analysing Materials By Optical Means (AREA)
• Position Fixing By Use Of Radio Waves (AREA)

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• 2021
  • 2021-12-07 FR FR2113054A patent/FR3130031B1/fr active Active
• 2022
  • 2022-11-24 CA CA3236846A patent/CA3236846A1/fr active Pending
  • 2022-11-24 US US18/714,128 patent/US20250043925A1/en active Pending
  • 2022-11-24 WO PCT/EP2022/083076 patent/WO2023104528A1/fr not_active Ceased
  • 2022-11-24 EP EP22822030.7A patent/EP4445111A1/de active Pending

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