Claims:1. A system comprising:
a plurality of passive absorption cells distributed across an asset and configured to allow diffusion of a gas leaked from the asset into the plurality of passive absorption cells resulting in presence of diffused leaked gas inside at least one of the plurality of passive absorption cells;
a fiber optic network;
a remote analyzer operationally and isotropically coupled to the plurality of passive absorption cells via the fiber optic network, wherein the remote analyzer comprises:
a radiation source operationally coupled to the plurality of passive absorption cells via the fiber optic network and configured to emit electromagnetic radiation to irradiate the diffused leaked gas resulting in emission of modified electromagnetic radiation;
a detector operationally coupled to the plurality of passive absorption cells via the fiber optic network and configured to detect one or more characteristics of the modified electromagnetic radiation; and
a processing subsystem operationally coupled to the detector and configured to determine absorption of a portion of the electromagnetic radiation by the diffused leaked gas based on the one or more characteristics of the modified electromagnetic radiation and determine one or more of a presence of a gas leakage and a location of the gas leakage in the asset, based on the absorption of the portion of the electromagnetic radiation,
wherein the electromagnetic radiation is characterized by a wavelength range corresponding to absorption lines of the leaked gas or an individual gas present in the leaked gas if the leaked gas is a gas-mixture, and
wherein each passive absorption cell is further configured to direct the electromagnetic radiation such that an interaction length of the electromagnetic radiation with the diffused leaked gas that is greater than a physical dimension of the corresponding passive absorption cell.

2. The system of claim 1, wherein the processing subsystem is further configured to determine the location of the gas leakage by:
determining concentrations of the diffused leaked gas in the plurality of passive absorption cells;
comparing the concentrations of the diffused gas to a determined threshold;
determining a subset of the concentrations of the diffused gas that exceeds the determined threshold based on the comparison;
selecting a subset of the plurality of passive absorption cells that correspond to the subset of the concentrations; and
determining the location of the gas leakage based on a position of the subset of the plurality of passive absorption cells.

3. The system of claim 1, wherein the processing subsystem is further configured to determine the presence of the gas leakage in the asset further based on an atmospheric temperature.

4. The system of claim 1, further comprising a switch coupled to the plurality of passive absorption cells and configured to selectively switch transmission of the electromagnetic radiation between the plurality of passive absorption cells.

5. The system of claim 4, further comprising a circulator operationally coupled to the radiation source, the switch, and the detector and configured to direct the electromagnetic radiation from the radiation source to the switch and the modified electromagnetic radiation from the switch to the detector.

6. The system of claim 1, wherein the radiation source comprises a coherent source, an incoherent source, a visible light source, an infrared source, or a combination thereof, and wherein the electromagnetic radiation comprises a laser beam.

7. The system of claim 1, wherein the wavelength range is from about 1.6 micrometer to about 1.7 micrometer.

8. The system of claim 1, wherein the leaked gas comprises natural gas including methane, or a gas-mixture comprising individual gases.

9. The system of claim 1, wherein the wavelength range comprises a near-infrared range, a short-wavelength range or a mid-infrared range.

10. The system of claim 1, wherein the plurality of passive absorption cells comprises one or more hollow integrating spheres.

11. The system of claim 1, wherein a passive absorption cell from the plurality of passive absorption cells, comprises:
an integrating sphere comprising a first perforation and a second perforation;
a superhydrophobic scattering layer coated on an inner surface of the integrating sphere; and
a diffusor disposed on the first perforation,
wherein the diffusor is configured to diffuse the gas leaked from the asset into the passive absorption cell and wherein the second perforation is configured to operationally couple the passive absorption cell to the radiation source and the detector.

12. The system of claim 11, wherein the superhydrophobic scattering layer comprises one or more of micro-structured silica, titania, differentially patterned aligned carbon nanotube, plasma polymerization/etching of polypropylene in the presence of polytetrafluoroethylene (PTFE), fluroalkylsilane.

13. The system of claim 11, wherein the diffusor comprises a membrane permeable to the leaked gas.

14. A system comprising:
a plurality of passive absorption cells distributed proximate to an asset and configured to allow diffusion of a gas leaked from the asset into the plurality of passive absorption cells resulting in presence of a diffused leaked gas inside the plurality of passive absorption cells;
a fiber optic network comprising a first optical fiber and a second optical fiber;
a radiation source operationally coupled to the plurality of passive absorption cells via the fiber optic network, and configured to emit electromagnetic radiation to irradiate the diffused leaked gas resulting in emission of modified electromagnetic radiation;
a switch coupled to the plurality of passive absorption cells;
a circulator coupled to the radiation source via the first optical fiber and to the switch via the second optical fiber, wherein the circulator is configured to receive the electromagnetic radiation via the first optical fiber and direct the electromagnetic radiation to the switch via the second optical fiber, wherein the switch is configured to selectively direct the electromagnetic radiation to one of the plurality of passive absorption cells resulting in emission of modified electromagnetic radiation from the corresponding one of the plurality of passive absorption cells;
a detector operationally coupled to the plurality of passive absorption cells via the fiber optic network, and configured to detect one or more characteristics of the modified electromagnetic radiation; and
a processing subsystem operationally coupled to the detector and configured to determine absorption of a portion of the electromagnetic radiation by the diffused leaked gas based on the one or more characteristics of the modified electromagnetic radiation and determine presence of a gas leakage in the asset based on the absorption of the portion of the electromagnetic radiation,
wherein the electromagnetic radiation is characterized by a wavelength range corresponding to absorption lines of the leaked gas or an individual gas present in the leaked gas if the leaked gas is a gas-mixture and wherein each passive absorption cell is further configured to direct the electromagnetic radiation such that an interaction length of the electromagnetic radiation with the diffused leaked gas that is greater than a physical dimension of the corresponding passive absorption cell.

15. The system of claim 14, wherein the switch is coupled to the plurality of passive absorption cells via a plurality of corresponding third optical fibers.

16. The system of claim 15, wherein a passive absorption cell from the plurality of passive absorption cells is coupled to the switch via a corresponding third optical fiber from the plurality of corresponding third optical fibers, and wherein the electromagnetic radiation is directed from the switch to the passive absorption cell via the corresponding third optical fiber and the modified electromagnetic radiation is directed from the passive absorption cell to the switch via the corresponding third optical fiber.

17. A system, comprising:
a plurality of passive absorption cells distributed proximate to an asset and configured to allow diffusion of leaked gas from the asset to at least one of the plurality of passive absorption cells resulting in presence of a diffused leaked gas inside the one of the plurality of passive absorption cells;
a radiation source operationally coupled to the plurality of passive absorption cells via a fiber optic network, and configured to emit laser beam to irradiate the diffused leaked gas resulting in emission of modified laser beam;
a detector operationally coupled to the plurality of passive absorption cells via the fiber optic network, and configured to detect one or more characteristics of the modified laser beam; and
a processing subsystem operationally coupled to the detector and configured to determine absorption of a portion of the laser beam by methane present in the diffused leaked gas based on the one or more characteristics of the modified laser beam and determine presence of a gas leakage in the asset based on the absorption of the portion of the laser beam,
wherein the laser beam is characterized by a wavelength in a range of about 1.6 micrometer to about 1.7 micrometer and wherein each passive absorption cell is further configured to direct the laser beam such that an interaction length of the laser beam with the diffused leaked gas that is greater than a physical dimension of the corresponding passive absorption cell.

18. The system of claim 17, further comprising a switch coupled to the plurality of passive absorption cells and configured to selectively switch transmission of the laser beam between the plurality of passive absorption cells.

19. A method comprising:
passively diffusing a gas leaked from an asset to a plurality of passive absorption cells disposed proximate to the asset resulting in presence of a diffused leaked gas inside the plurality of passive absorption cells;
emitting electromagnetic radiation to the plurality of passive absorption cells to irradiate the diffused leaked gas resulting in emission of modified electromagnetic radiation;
detecting one or more characteristics of the modified electromagnetic radiation;
detecting absorption of a portion of the electromagnetic radiation by the diffused leaked gas based on the one or more characteristics of the modified electromagnetic radiation; and
determining a presence of leakage in the asset and a location of the leakage in the asset based on the absorption of the portion of the electromagnetic radiation,
wherein the electromagnetic radiation is characterized by a wavelength range corresponding to absorption lines of the leaked gas or an individual gas present in the leaked gas if the leaked gas is a gas-mixture and wherein each passive absorption cell is further configured to direct the electromagnetic radiation such that an interaction length of the electromagnetic radiation with the diffused leaked gas that is greater than a physical dimension of the corresponding passive absorption cell.

20. The method of claim 19, wherein determining the location of the gas leakage comprises:
determining concentrations of the diffused leaked gas in the plurality of passive absorption cells;
comparing the concentrations of the diffused gas to a determined threshold;
determining a subset of the concentrations of the diffused gas that exceed the determined threshold based on the comparison;
selecting a subset of the plurality of passive absorption cells that correspond to the subset of the concentrations; and
determining the location of the gas leakage based on a position of the subset of the plurality of passive absorption cells.
, Description:BACKGROUND
[0001] Embodiments of the present invention relate generally to monitoring systems for assets, and more particularly to a system and method for detecting gas leakage in ambient environment and location of leakage in assets.
[0002] Typically assets, such as oil and gas assets, mining wells, and pipelines, are either distributed in large areas and/or located at remote locations from conventional communications equipment, user locations or inhabited locations. For example, pipelines are spread across large areas and are generally located at remote and almost inaccessible locations. Pipelines serve as a means of long-distance transport of gases and fluids and hence are expected to fulfill high demands of safety, reliability and efficiency. However, pipelines may leak due to corrosion at construction joints, low points where moisture collects, or locations with imperfections in the pipe. A pipeline may also leak due to a damage caused by a nearby excavation equipment.
[0003] Early detection of the leaks in assets limits fluid loss and may ensure the safety and integrity of such assets. However, retrieval of data related to the assets and monitoring of the assets is challenging due to remote and inaccessible locations of the assets. A variety of leak detection systems, such as visual based systems, resistivity measurement systems, and/or vibration measurement systems may be employed. Unfortunately, such systems may be expensive to procure, install and maintain, and may not detect leaks in real-time.
[0004] Accordingly, there is a need for an improved method and system to detect leaks and identify the location of the leaks in assets.
BRIEF DESCRIPTION
[0005] In accordance with one embodiment, a system is disclosed. The system includes a plurality of passive absorption cells distributed across an asset and configured to allow diffusion of a gas leaked from the asset into the plurality of passive absorption cells resulting in presence of diffused leaked gas inside at least one of the plurality of passive absorption cells. The system further includes a fiber optic network and a remote analyzer operationally and isotropically coupled to the plurality of passive absorption cells via the fiber optic network. The remote analyzer includes a radiation source operationally coupled to the plurality of passive absorption cells via the fiber optic network and configured to emit electromagnetic radiation to irradiate the diffused leaked gas resulting in emission of modified electromagnetic radiation. The remote analyzer further includes a detector operationally coupled to the plurality of passive absorption cells and configured to detect one or more characteristics of the modified electromagnetic radiation. The remote analyzer further includes a processing subsystem operationally coupled to the detector and configured to determine absorption of a portion of the electromagnetic radiation by the diffused leaked gas based on the one or more characteristics of the modified electromagnetic radiation. The processing subsystem is further configured to determine one or more of a presence of a gas leakage and a location of the gas leakage, in the asset in ambient environment, based on the absorption of the portion of the electromagnetic radiation. The electromagnetic radiation is characterized by a wavelength range corresponding to absorption lines of the leaked gas or an individual gas present in the leaked gas if the leaked gas is a gas-mixture. Each passive absorption cell is further configured to direct the electromagnetic radiation such that an interaction length of the electromagnetic radiation with the diffused leaked gas is greater than a physical dimension of the corresponding passive absorption cell.
[0006] In accordance with another embodiment, a system is disclosed. The system includes a plurality of passive absorption cells distributed proximate to an asset and configured to allow diffusion of a gas leaked from the asset into the plurality of passive absorption cells resulting in presence of a diffused leaked gas inside the plurality of passive absorption cells. The system further includes a fiber optic network comprising a first optical fiber and a second optical fiber. The system further includes a radiation source operationally coupled to the plurality of passive absorption cells via the fiber optic network and configured to emit electromagnetic radiation to irradiate the diffused leaked gas resulting in emission of modified electromagnetic radiation. The system further includes a switch coupled to the plurality of passive absorption cells. The system further includes a circulator coupled to the radiation source via the first optical fiber and to the switch via the second optical fiber. The circulator is configured to receive the electromagnetic radiation via the first optical fiber and direct the electromagnetic radiation to the switch via the second optical fiber. The switch is configured to selectively direct the electromagnetic radiation to one of the plurality of passive absorption cells resulting in emission of modified electromagnetic radiation from the corresponding one of the plurality of passive absorption cells. A detector is operationally coupled to the plurality of passive absorption cells and configured to detect one or more characteristics of the modified electromagnetic radiation. A processing subsystem is operationally coupled to the detector and configured to determine absorption of a portion of the electromagnetic radiation by the diffused leaked gas based on the one or more characteristics of the modified electromagnetic radiation and determine presence of a gas leakage in the asset based on the absorption of the portion of the electromagnetic radiation. The electromagnetic radiation is characterized by a wavelength range corresponding to absorption lines of the leaked gas or an individual gas present in the leaked gas if the leaked gas is a gas-mixture. Each passive absorption cell is further configured to direct the electromagnetic radiation such that an interaction length of the electromagnetic radiation with the diffused leaked gas is greater than a physical dimension of the corresponding passive absorption cell.
[0007] In accordance with yet another embodiment, a system is disclosed. The system includes a plurality of passive absorption cells distributed proximate to an asset and configured to allow diffusion of leaked gas from the asset to at least one of the plurality of passive absorption cells resulting in presence of a diffused leaked gas inside the one of the plurality of passive absorption cells. The system further includes a radiation source operationally coupled to the plurality of passive absorption cells and configured to emit laser beam to irradiate the diffused leaked gas resulting in emission of modified laser beam. Additionally, the system includes a detector operationally coupled to the plurality of passive absorption cells and configured to detect one or more characteristics of the modified laser beam.
[0008] Furthermore, the system includes a processing subsystem operationally coupled to the detector and configured to determine absorption of a portion of the laser beam by methane present in the diffused leaked gas based on the one or more characteristics of the modified laser beam. The processing subsystem is further configured to determine presence of a gas leakage in the asset based on the absorption of the portion of the laser beam. The laser beam is characterized by a wavelength in a range of about 1.6 micrometer to about 1.7 micrometer. Each passive absorption cell is further configured to direct the electromagnetic radiation such that an interaction length of the electromagnetic radiation with the diffused leaked gas is greater than a physical dimension of the corresponding passive absorption cell.
[0009] In accordance with yet another embodiment, a method is disclosed. The method includes passively diffusing a gas leaked from an asset to a plurality of passive absorption cells disposed proximate to the asset resulting in presence of a diffused leaked gas inside the plurality of passive absorption cells. The method further includes emitting electromagnetic radiation to the plurality of passive absorption cells to irradiate the diffused leaked gas resulting in emission of modified electromagnetic radiation and detecting one or more characteristics of the modified electromagnetic radiation. The method additionally includes detecting absorption of a portion of the electromagnetic radiation by the diffused leaked gas based on the one or more characteristics of the modified electromagnetic radiation and determining a presence of leakage in the asset and a location of the leakage in the asset based on the absorption of the portion of the electromagnetic radiation. The electromagnetic radiation is characterized by a wavelength range corresponding to absorption lines of the leaked gas or an individual gas present in the leaked gas if the leaked gas is a gas-mixture. Each passive absorption cell is further configured to direct the electromagnetic radiation such that an interaction length of the electromagnetic radiation with the diffused leaked gas is greater than a physical dimension of the corresponding passive absorption cell.
DRAWINGS
[0010] These and other features and aspects of embodiments of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
[0011] Fig. 1 is a block diagram of a system configured to determine presence of a gas leakage in an asset in accordance with one embodiment of the present invention;
[0012] Fig. 2 is a block diagram of a system configured to determine presence of a gas leakage in an asset in accordance with another embodiment of the present invention;
[0013] Fig. 3 is a schematic diagram of a passive absorption cell in accordance with one embodiment of the present invention;
[0014] Fig. 4 is a flow chart that illustrates an exemplary method to determine presence of a gas leakage in an asset in accordance with one embodiment of the present invention; and
[0015] Fig. 5 is a block diagram of a system configured to determine a location of a gas leakage in an asset in accordance with one embodiment of the present invention.
DETAILED DESCRIPTION
[0016] Unless defined otherwise, technical and scientific terms used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs. The terms “a” and “an” do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items. The term “or” is meant to be inclusive and mean one, some, or all of the listed items. The use of “including,” “comprising” or “having” and variations thereof herein are meant to encompass the items listed thereafter and equivalents thereof as well as additional items.
[0017] As used herein, the terms “processor” and “computer” and related terms, e.g., “processing device”, “computing device”, and “controller” are not limited to just those integrated circuits referred to in the art as a computer, but broadly refers to a microcontroller, a microcomputer, a programmable logic controller (PLC), an application specific integrated circuit, and other programmable circuits, and these terms are used interchangeably herein. In the embodiments described herein, memory may include, but is not limited to, a computer-readable medium, such as a random access memory (RAM), and a computer-readable non-volatile medium, such as flash memory. Alternatively, a floppy disk, a compact disc, – read only memory (CD-ROM), a magneto-optical disk (MOD), and/or a digital versatile disc (DVD) may also be used. Also, in the embodiments described herein, additional input channels may be, but are not limited to, computer peripherals associated with an operator interface such as a mouse and a keyboard. Alternatively, other computer peripherals may also be used that may include, for example, but not be limited to, a scanner. Furthermore, in the exemplary embodiment, additional output channels may include, but not limited to, an operator interface monitor.
[0018] The terms “control system” or “controller” may include either a single component or a plurality of components which are either active and/or passive and are connected or otherwise coupled together to provide the described function or functions.
[0019] Embodiments of the present invention disclose determining presence of a gas leakage in assets in ambient environments. The assets, for example, may include compressor stations, mines, well pads, refineries, pipelines, or other assets susceptible to gas build-up or leakage. Particularly, embodiments of the present invention disclose determining presence of a gas leakage in the assets remotely and in real time. While the embodiments of the present invention are explained with reference to pipelines, it should not be construed as a limitation of the invention. Furthermore, embodiments of the present invention disclose determining the location of a gas leakage in the assets. More specifically embodiments of the present invention disclose distributed/multipoint sensing of trace methane leaked from an asset located over a large area, using a single remotely located laser based analyzer.
[0020] Fig. 1 is a block diagram of a system 100 configured to determine presence of a gas leakage and location of the gas leakage in an asset 102 in accordance with one embodiment of the present invention. In the illustrated embodiment, the asset 102 represents a gas pipeline. It should be noted herein that while the system 100 is explained with reference to the asset 102, it should not be construed as a limitation of the invention. The asset 102, for example, transfers a gas 106 from a first location to a second location. The gas 106, for example, may be a gas-mixture which is a mixture of individual gases. The gas-mixture, for example, may be natural gas and the like. In some embodiments, the system 100 may be configured to identify a leakage in the asset 102 by identifying presence of methane in leaked natural gas.
[0021] The system 100 includes a plurality of passive absorption cells 108, 110, 112 (also referred to herein as the first passive absorption cell 108, the second passive absorption cell 110, and the third passive absorption cell 112) distributed proximate to the asset 102. The passive absorption cells 108, 110, 112, for example, may be located at a distance of less than or equal to 100 meters from the asset 102. The passive absorption cells 108, 110, 112, for example, may be hollow integrating spheres having one or more coatings on an inner surface. The passive absorption cells 108, 110, 112 are configured to allow passive diffusion of a gas that surrounds or is in proximity to the passive absorption cells 108, 110, 112. Whenever one or more gas leaks occur in the asset 102, one or more of the passive absorption cells 108, 110, 112 located adjacent to the gas leak, allows passive diffusion of the gas leaked from the asset 102 into one or more of the passive absorption cells 108, 110, 112. The leaked gas, for example, may contain methane, ethane, hydrogen sulphide (H2S), or the like. The diffusion of the leaked gas or one or more individual gases present in the leaked gas (for example: methane present in leaked natural gas) into the passive absorption cells 108, 110, 112, results in presence of a portion of the leaked gas inside the passive absorption cells 108, 110, 112. Hereinafter, the portion of the leaked gas inside the passive absorption cells may be referred to as “diffused leaked gas.” For example, when a gas leak initiates at a location 114 in the asset 102, due to the proximity of the passive absorption cell 112 to the location 114, the leaked gas (not shown) diffuses into the passive absorption cell 112. It should be noted herein that while the embodiment of Fig. 1 shows three passive absorption cells 108, 110, 112, the number of passive absorption cells in the system 100 may vary depending on the application. For example, for a greater number of distributed assets, a greater number of passive absorption cells may be used. In one embodiment, emitted electromagnetic radiation is directed into the passive absorption cells 108, 110, 112. Each passive absorption cell 108, 110, 112 is configured to enhance an interaction length of the electromagnetic radiation, with the diffused leaked gas that flows into the corresponding passive absorption cell 108, 110, 112, which is greater than a physical dimension of the corresponding passive absorption cell 108, 110, 112. For example, if the passive absorption cells 108, 110, 112 are integrating spheres, each of the absorption cells 108, 110, 112 direct the electromagnetic radiation such that interaction length of the electromagnetic radiation with the diffused leaked gas is greater than a diameter of the passive absorption cells 108, 110, 112. In certain embodiments, the passive absorption cells 108, 110, 112 may be Herriott cell or a white cell.
[0022] The system 100 further includes a remote analyzer 115 isotropically and operationally coupled to the passive absorption cells 108, 110, 112 via a fiber optic network 117. The fiber optic network 117, for example, includes a main optical fiber 118 and branch optical fibers 120, 122, 124. The main optical fiber 118 and the branch optical fibers 120, 122, 124, for example, may be a multi-mode optical fiber or a single mode optical fiber. The remote analyzer 115 is configured to determine the presence of the gas leakage and the location of the gas leakage in the asset 102. The remote analyzer 115 is insensitive to a change in a position and orientation of the passive absorption cells 108, 110, 112 due to the isotropic coupling of the remote analyzer 115 to the absorption cells 108, 110, 112. Hence, the remote analyzer 115 is configured to determine the presence of the gas leakage and location of the gas leakage accurately irrespective of environmental changes or change in position or orientation of the absorption cells 108, 110, 112. Additionally, since the remote analyzer 115 is configured to determine the presence of the gas leakage and the location of the gas leakage, there is no need to transfer a sample of gas to a laboratory for detection of the presence of the gas leakage. The remote analyzer 115 is a quantitative system that is configured to determine a concentration of the diffused leaked gases and the location of the diffused leaked gases based on the concentration of the diffused leaked gases.
[0023] In the illustrated embodiment, the remote analyzer 115 includes a radiation source 116 operationally coupled to the passive absorption cells 108, 110, 112. The radiation source 116 may be a coherent source, an incoherent source, a visible light source, an infrared source, a quantum cascade laser, a light emitting diode, a superluminescent laser diode, or the like. The radiation source 116, for example, may be coupled to each of the passive absorption cells 108, 110, 112 via the main optical fiber 118 and respective branch optical fibers 120, 122, 124. In the illustrated embodiment, the radiation source 116 is coupled to the first passive absorption cell 108 via the main optical fiber 118 and the branch optical fiber 120. Additionally, the radiation source 116 is coupled to the second passive absorption cell 110 via the main optical fiber 118 and the branch optical fiber 122. Similarly, the radiation source 116 is coupled to the third passive absorption cell 112 via the main optical fiber 118 and the branch optical fiber 124.
[0024] The radiation source 116 is configured to emit electromagnetic radiation 126. Due to the coupling of the radiation source 116 to the passive absorption cells 108, 110, 112 via the main optical fiber 118 and respective branch optical fibers 120, 122, 124, the electromagnetic radiation 126 is isotropically coupled to the passive absorption cells 108, 110, 112. The electromagnetic radiation 126, for example, may be infrared rays, visible light, a laser beam, or the like. The electromagnetic radiation 126 transmits through the main optical fiber 118 and one or more of the branch optical fibers 120, 122, 124. Then the electromagnetic radiation 126 irradiates the diffused leaked gas in one or more of the passive absorption cells 108, 110, 112. In one embodiment, the electromagnetic radiation 126 utilized for leak detection, is characterized by a wavelength range corresponding to absorption lines of the leaked gas. In another embodiment, if the leaked gas is a mixture of individual gases, the electromagnetic radiation 126 utilized for leak detection, is characterized by a wavelength range of one of the individual gases present in the leaked gas. For example, if the asset 102 transfers natural gas which is a mixture of individual gases including methane, the electromagnetic radiation 126 utilized for leak detection, may be characterized by a wavelength range corresponding to absorption lines of methane. For example, in the case of methane, the electromagnetic radiation 126 may be characterized by a wavelength range from about 1.6 micrometers to about 1.7 micrometers. In another embodiment, the wavelength range may include a near-infrared range, a short-wavelength range or a mid-infrared range. The irradiation of the diffused leaked gas by the electromagnetic radiation 126 results in absorption of at least a portion of the electromagnetic radiation 126 by the portion of leaked gas, or an individual gas present in the diffused leaked gas in the passive absorption cells 108, 110, 112. The absorption of the portion of the electromagnetic radiation 126 by the diffused leaked gas results in emission of a modified electromagnetic radiation 128. The modified electromagnetic radiation 128 transmits from the passive absorption cells 108, 110, 112 via the respective branch optical fibers 120, 122, 124 and then the main optical fiber 118 back to the remote analyzer 115.
[0025] The remote analyzer 115 further includes a detector 130 operationally coupled to the passive absorption cells 108, 110, 112. The detector 130 is configured to detect one or more characteristics of the modified electromagnetic radiation 128. The characteristics, for example, may include intensity of the modified electromagnetic radiation 128, spectral distribution of intensity of the modified electromagnetic radiation 128, or the like.
[0026] The remote analyzer 115 further includes a processing subsystem 132 operationally coupled to the detector 130. The processing subsystem 132 is configured to determine absorption of a portion of the electromagnetic radiation 126 by the diffused leaked gas based on the one or more characteristics of the modified electromagnetic radiation 128. In one embodiment, the processing subsystem 132 is configured to determine the absorption of the portion of the electromagnetic radiation 126 based on the intensity of the modified electromagnetic radiation 128 and an intensity of the electromagnetic radiation 126. Furthermore, the processing subsystem 132 is configured to determine presence of the gas leakage in the asset 102 based on the absorption of the portion of the electromagnetic radiation 126. For example, if the processing subsystem 132 determines that the absorption of the portion of the electromagnetic radiation 126 is greater than a predefined threshold, then it may be determined that a gas leakage is present in the asset 102. Furthermore, the processing subsystem 132 may be configured to determine a location of the gas leakage based on a location of one or more of the passive absorption cells 108, 110, 112 where the absorption of the portion of the electromagnetic radiation 126 occurs. Determination of the location of the gas leakage is explained in greater detail with reference to Fig. 5.
[0027] Fig. 2 is a block diagram of a system 200 configured to determine presence of a gas leakage in an asset 202 in accordance with another embodiment of the present invention. For ease of description, the asset 202 is shown as a gas pipeline in the illustrated embodiment. The asset 202, for example, transfers a gas 206 from a first location to a second location. The system 200 includes a plurality of passive absorption cells 208, 210 (also referred to herein as the first passive absorption cell 208 and the second passive absorption cell 210) configured to allow passive diffusion of a gas to the passive absorption cells 208, 210. Whenever one or more gas leaks occur in the asset 202, one or more of the passive absorption cells 208, 210 located adjacent the gas leak, allows passive diffusion of the gas leaked from the asset 202. The diffusion of the leaked gas into the passive absorption cells 208, 210 results in presence of a diffused leaked gas inside the passive absorption cells 208, 210.
[0028] Furthermore, the system 200 includes a radiation source 216, a circulator 218, a switch 220, a processing subsystem 222, and a fiber optic network. The fiber optic network includes a first optical fiber 224, a second optical fiber 227, and a third optical fiber 230. The radiation source 216 is operationally coupled to the circulator 218. In the illustrated embodiment, the radiation source 216 is coupled to the circulator 218 via the first optical fiber 224. The radiation source 216 is configured to emit an electromagnetic radiation 226 and direct the electromagnetic radiation 226 to the circulator 218 via the first optical fiber 224.
[0029] The circulator 218 is coupled to the switch 220 via the second optical fiber 227. The circulator 218 is configured to direct the electromagnetic radiation 226 to the switch 220 via the second optical fiber 227. The switch 220 is operationally coupled to the passive absorption cells 208, 210 via the third optical fiber 230. Furthermore, the switch 220 is operationally coupled to the processing subsystem 222. The processing subsystem 222 is configured to control the switch 220 to selectively switch the electromagnetic radiation 226 to one of the passive absorption cells 208, 210. For example, the processing subsystem 222 may be configured to direct the electromagnetic radiation 226 sequentially to the passive absorption cells 208, 210. In the illustrated embodiment, the processing subsystem 222 controls the switch 220 at a time stamp t to direct the electromagnetic radiation 226 to the second passive absorption cell 210. As previously noted, due to the leak in the asset 202 at the location 214, the leaked gas diffuses into the second passive absorption cell 210. Furthermore, since the electromagnetic radiation 226 is directed into the second passive absorption cell 210 the diffused leaked gas is irradiated in the second passive absorption cell 210, resulting in emission of a modified electromagnetic radiation 228.
[0030] The modified electromagnetic radiation 228 transmits via the third optical fiber 230 to the switch 220. The switch 220 directs the modified electromagnetic radiation 228 to the circulator 218. The circulator 218 directs the modified electromagnetic radiation 228 to a detector 232. In the illustrated embodiment, the detector 232 determines an intensity 234 of the modified electromagnetic radiation 228. Furthermore, the detector 232 transmits the intensity 234 of the modified electromagnetic radiation 228 to the processing subsystem 222.
[0031] The processing subsystem 222 is configured to determine absorption of a portion of the electromagnetic radiation 226 by the diffused leaked gas based on the intensity 234 of the modified electromagnetic radiation 228. Particularly, the processing subsystem 222 may determine the absorption of the portion of the electromagnetic radiation 226 based on the intensity 234 of the modified electromagnetic radiation 228 and an intensity of the electromagnetic radiation 226. Furthermore, the processing subsystem 222 is configured to determine the presence of the gas leakage in the asset 202 based on the absorption of the portion of the electromagnetic radiation 226. For example, if the processing subsystem 222 determines that the absorption of the portion of the electromagnetic radiation 226 is greater than a predefined threshold, then it may be determined that a gas leakage is present in the asset 202.
[0032] In one embodiment, the processing subsystem 222 may determine the presence of the gas leakage in the asset 202 further based on an atmospheric temperature. The processing subsystem 222 may be further configured to determine concentrations of the diffused leaked gas in the passive absorption cells 208, 210. The processing subsystem 222 may determine the presence of the gas leakage in the asset 202 and the concentrations of the diffused leaked gas in the passive absorption cells 208, 210 using Beer Lambert law. An example of the Beer Lambert law is shown below:

wherein I is the intensity a modified electromagnetic radiation 228, I0 is an intensity of the electromagnetic radiation 226, C is concentration of diffused leaked gas, L is a path length of the electromagnetic radiation inside the passive absorption cells 208, 210, and a is an absorbance coefficient that is a function of the atmospheric temperature.
[0033] Additionally, the processing subsystem 222 is configured to determine a location of the gas leakage based on the concentrations of the diffused leaked gas and respective locations of one or more of the passive absorption cells 208, 210. In the illustrated embodiment, the processing subsystem 222 determines the location of the gas leakage as the location proximate to the location of the second passive absorption cell 210. An example for determination of the diffused leaked gas is explained with reference to Fig. 5.
[0034] Fig. 3 is a diagrammatic illustration of a passive absorption cell 300 in accordance with one embodiment of the present invention. In the illustrated embodiment, the passive absorption cell 300 is a spherical absorption cell. The passive absorption cell 300, for example, is a metallic hollow integrating sphere. The passive absorption cell 300 includes a first perforation 302 and a second perforation 304. A diffusor 306 is disposed on the first perforation 302 to allow passive diffusion of a portion of a leaked gas surrounding or in-proximity to the location of the passive absorption cell 300. Particularly, the diffusor 306 is configured to diffuse the diffused leaked gas into the passive absorption cell 300. For example, the diffusor 306 may be a membrane permeable to the leaked gas.
[0035] The second perforation 304 is configured to operationally couple the passive absorption cell 300 to a radiation source (not shown) via an optical fiber 308. The radiation source, for example, may be the radiation source 116 or the radiation source 216 shown in Fig. 1 and Fig. 2 respectively. The passive absorption cell 300 may be directly or indirectly coupled to the radiation source. In one embodiment, the passive absorption cell 300 may be coupled to a switch (not shown) via the optical fiber 308. The switch may be coupled to the radiation source via the same optical fiber 308 or another optical fiber. The optical fiber 308, for example, is configured to transmit electromagnetic radiation emitted by the radiation source to the passive absorption cell 300 whereby the electromagnetic radiation interacts with a diffused leaked gas within the passive absorption cell 300 resulting in a modified electromagnetic radiation. Furthermore, the optical fiber 308 may be configured to transmit a modified electromagnetic radiation to a detector. In one embodiment, the optical fiber 308 may transmit the modified electromagnetic radiation from the passive absorption cell 300 to the switch and the switch may thereafter transfer the modified electromagnetic radiation to the detector.
[0036] In the illustrated embodiment, a coupling lens 310 is coupled to the second perforation 304. In one embodiment, the coupling lens 310 covers the second perforation 304. In one embodiment, the coupling lens 310 receives the electromagnetic radiation from the optical fiber 308 and scatters the electromagnetic radiation inside the passive absorption cell 300.
[0037] Furthermore, the passive absorption cell 300 is coated with a superhydrophobic scattering layer 312 on an inner surface 314. The superhydrophobic scattering layer 312, for example, may include micro-structured silica, titania, differentially patterned aligned carbon nanotube, plasma polymerization/etching of polypropylene in the presence of polytetrafluoroethylene (PTFE), fluroalkylsilane, or the like. The superhydrophobic scattering layer 312 provides anti-corrosive and anti-icing properties to the passive absorption cell 300. Additionally, the superhydrophobic scattering layer 312 is configured to prevent dew formation in the passive absorption cell 300.
[0038] Fig. 4 is a flow chart that illustrates an exemplary method 400 to determine presence of a gas leakage in an asset in accordance with one embodiment of the present invention. In the illustrated embodiment, the asset is a gas pipeline. It should be noted herein that while the method is explained with reference to the gas pipeline, it should not be construed as a limitation of the invention. At block 402, a portion of gas leaked from a gas pipeline passively diffuses into one or more passive absorption cells. As noted herein, the passive absorption cells are disposed in proximity to the passive absorption cells and are configured to allow passive diffusion of a gas that surrounds or is in proximity to the passive absorption cells. Whenever one or more gas leaks occur in the gas pipeline, one or more of the passive absorption cells located adjacent the gas leak, allows passive diffusion of the leaked gas from the gas pipeline into one or more of the passive absorption cells. The diffusion of the leaked gas into one or more of the passive absorption cells, results in presence of a diffused leaked gas in one or more of the passive absorption cells.
[0039] Furthermore, at block 404 an electromagnetic radiation is emitted by a radiation source to the passive absorption cells. The electromagnetic radiation, for example, may be a laser beam. The electromagnetic radiation transmits through an optical fiber that connects the radiation source directly or indirectly to the passive absorption cells. Transmission of the electromagnetic radiation via the optical fiber to the passive absorption cells results in irradiation of the diffused leaked gas inside one or more of the passive absorption cells resulting in emission of a modified electromagnetic radiation. At block 406, the modified electromagnetic radiation is emitted from the passive absorption cells to a detector. In one embodiment, the modified electromagnetic radiation is emitted from the passive absorption cell to the detector via a switch and a circulator.
[0040] At block 408, one or more characteristics, such as an intensity of the modified electromagnetic radiation may be determined by the detector. The detector, for example, may transmit the one or more characteristics to a processing subsystem. At block 410, the absorption of the portion of the electromagnetic radiation by the diffused leaked gas is determined. Specifically, the absorption of the portion of the electromagnetic radiation by the diffused leaked gas is determined based on the one or more characteristics of the modified electromagnetic radiation. Furthermore, at block 412 a presence of a leakage in the gas pipeline is determined. For example, if the absorption of the portion of the electromagnetic radiation by the diffused leaked gas in the passive absorption cells is greater than a predefined threshold value, then it is determined that a gas leakage is present in the gas pipeline. In certain embodiments, the location of the gas leakage may be determined based on the location of the passive absorption cells where the absorption of the portion of the electromagnetic radiation occurs.
[0041] Fig. 5 is a block diagram of a system 500 configured to determine a location of a gas leakage in an asset 520 in accordance with one embodiment of the present invention. The system 500 includes a remote analyzer 502 and a plurality of passive absorption cells 504, 506, 508, 510, 512, 514, 516, 518 distributed across the asset 520. The remote analyzer 502 is configured to determine concentrations of diffused leaked gas, if any, in the passive absorption cells 504, 506, 508, 510, 512, 514, 516, 518.
[0042] The remote analyzer 502 is configured to compare the concentrations of the diffused gas to a determined threshold. Furthermore, the remote analyzer 502 is configured to determine a subset of the concentrations that exceed the determined threshold. Thereafter, the remote analyzer 502 is configured to select a subset of the passive absorption cells 504, 506, 508, 510, 512, 514, 516, 518 that correspond to the subset of the concentrations and determine the location of the gas leakage based on the position of the subset of the plurality of passive absorption cells 504, 506, 508, 510, 512, 514, 516, 518. An example of determination of the locations of the gas leakage is explained hereinafter.
[0043] In the illustrated embodiment, the remote analyzer 502 determines the concentrations in the passive absorption cells 504, 506, 508, 510, 512, 514, 516, 518 as shown in the following Table 1:
Passive absorption cell reference numeral Concentrations of diffused leaked gas in the passive absorption cells
504 0.5 ppm
506 1.1 ppm
508 5 ppm
510 6 ppm
512 0.8 ppm
514 2 ppm
516 4 ppm
518 4.5 ppm

[0044] Furthermore, if a value of the determined threshold is 3 ppm, for example, then the remote analyzer 502 compares the concentrations (shown in Table 1) of the diffused gas to 3 ppm. In the illustrated embodiment, the remote analyzer 502 determines that the concentrations of the diffused leaked gas in the passive absorption cells 508, 510, 516, 518 exceed the determined threshold of 3 ppm. Accordingly, the remote analyzer 502 selects the passive absorption cells 508, 510, 516, 518 and determines the location of the gas leakage in proximity to the passive absorption cells 508, 510, 516, 518. The reference numeral 522 is indicative of a region that is in proximity to the passive absorption cells 508, 510, 516, 518. Accordingly, the remote analyzer 502 determines the region 522 as the location of the gas leakage.
[0045] Embodiments of the present system and method relate to a fugitive gas emissions management system that includes a weather-independent multipoint distributed ambient sensing methodology. Embodiments of the present invention disclose real-time, cost-effective and robust techniques for determination of gas leakage along large pipelines. In accordance with the embodiments of the present invention, unlike conventional systems and methods, there is no requirement to carry a sample of fluid from the vicinity of assets to a laboratory. For example, embodiments of the present invention disclose distributed and multipoint sensing of trace methane over a large area, using a single remotely located laser based analyzer. Furthermore, embodiments of the present invention disclose determining location of a gas leakage in an asset.
[0046] While only certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.