Abstract:
Sensors locate troublesome leaks in pipes or conduits that carry a flowing medium. These sensors, through tailored physical and geometric properties, preferentially seek conduit leaks or breaches due to flow streaming. The sensors can be queried via transceivers outside the conduit or located and interrogated inside by submersible unmanned vehicle to identify and characterize the nature of a leak. The sensors can be functionalized with other capabilities for additional leak and pipeline characterization if needed. Sensors can be recovered from a conduit flow stream and reused for future leak detection activities.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional patent application Ser. No. 61/811,931, filed 15 Apr. 2013 (15.04.2013), which is hereby incorporated by reference in its entirety. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
       [0002]    This invention was made with government support under Contract No. DE-AC05-00OR22725 awarded by the U.S. Department of Energy. The government has certain rights in the invention. 
     
    
     THE NAMES OF THE PARTIES TO A JOINT RESEARCH AGREEMENT 
       [0003]    None. 
       BACKGROUND OF THE INVENTION 
       [0004]    1. Field of the Invention 
         [0005]    The present disclosure relates to sensors and more particularly to sensors and methods for locating a breach in a fluid-carrying conduit such as a pipeline. 
         [0006]    2. Description of the Related Art 
         [0007]    There are over 52,000 municipal water systems in the United States alone. Many of these systems are 100 years old or more and are experiencing large losses in the delivery of water due to infrastructure degradation. This so called “non-revenue water” can reduce system throughput by as much as 40% or more. A new business opportunity exists for a company that can quickly identify compromised water systems, and repair and maintain them for less than the expense of production of non-revenue water supplies. 
         [0008]    Several approaches have been attempted to identify and locate municipal water line leaks. In general, there are two primary methodologies for identifying leakage including aerial surveillance and pipeline inspection gauges (pigs). For aerial surveys, LiDAR mapping and high resolution videography are typically employed. In the case of pipeline pigs, several technologies have been applied including acoustic tomography, laser scanning or structured lighting, video imaging and even neutron tomography. For tunnel systems that are not near the surface or are covered by urban clutter, aerial surveillance is ineffective. Furthermore, methods employing pipeline pigs also provide sub-optimal performance due to the conditions within the water tunnel (e.g. water turbidity, presence of debris, complex pipeline geometries and size, etc.), or, in the case of neutron tomography, is exceedingly expensive. 
         [0009]    What is needed is a low-cost system and method for inspecting conduits to determine if a breach is present and, if so, locate the breach. 
       BRIEF SUMMARY OF THE INVENTION 
       [0010]    Disclosed are examples of a breach detection and location system and methods of detecting and locating breaches in a fluid-carrying conduit. Brief descriptions are provided here and more detailed descriptions follow. The term breach includes all leaks, openings, cracks, holes, gaps, misalignments, ruptures, breaks, separations, collapses, and other structural or assembly flaws that will allow a fluid medium (liquid or gas) to escape from a conduit such as a pipe, tube, vessel, duct, or the like. 
         [0011]    In one example, a breach detection and location system includes a plurality of uniquely identifiable Radio Frequency (RF) identification tags for introducing into an upstream point of a conduit that carries a fluid medium. A first transceiver is disposed on the outside of the conduit at a location that is proximate to the upstream point. A second transceiver is disposed on the outside of the conduit at a location that is proximate to a downstream point, with the downstream point being located downstream of the upstream point in the direction that the fluid medium flows. Each of the uniquely identifiable RF tags communicate individually with the first transceiver at a first time but only the uniquely identifiable RF tags that do not encounter a breach in the conduit communicate with the second transceiver at a later time. 
         [0012]    In yet another example, a method of detecting and locating a breach in a conduit carrying a flowing medium comprises the steps of: a) locating a first transceiver on the outside of the conduit at a location that is proximate to an upstream point; b) locating a second transceiver on the outside of the conduit at a location that is proximate to a downstream point, the downstream point being located downstream of the upstream point in the direction that the medium flows; c) introducing a plurality of uniquely identifiable Radio Frequency (RF) tags into the flowing medium at the upstream point; d) communicating with said plurality of uniquely identifiable Radio Frequency (RF) tags with said first transceiver at a first time; e) communicating with those uniquely identifiable Radio Frequency (RF) tags that pass through the conduit without encountering a breach with said second transceiver at a second time that is later than the first time; and f) comparing the communications of steps d) and e) to determine if any of the plurality of uniquely identifiable Radio Frequency (RF) tags are not present at the downstream point. 
         [0013]    These and other examples will now be described in greater detail below. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0014]    The system and method may be better understood with reference to the following drawings and description. Non-limiting and non-exhaustive descriptions are described with reference to the following drawings. The components in the figures are not necessarily to scale, emphasis instead being placed upon illustrating principles. In the figures, like referenced numerals may refer to like parts throughout the different figures unless otherwise specified. 
           [0015]      FIG. 1  illustrates an exemplary RF ID sensor in relation to the size of a typical human index finger. 
           [0016]      FIG. 2  illustrates an exemplary breach detection and location system. 
           [0017]      FIG. 3  illustrates an exemplary, two-piece, sensor pod. 
           [0018]      FIG. 4  illustrates an exemplary, one-piece, sensor pod. 
           [0019]      FIG. 5   illustrates  a time-lapse sequence of an exemplary sensor pod having increased buoyancy as it travels the length of a conduit. 
           [0020]      FIG. 6  illustrates a time-lapse sequence of an exemplary sensor pod having decreased buoyancy as it travels the length of a conduit. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0021]    This disclosure describes systems and methods for conduit leak detection and leak location using miniature wireless radio frequency (RF) identification (ID) sensors RF or RF ID sensors as they are commonly referred to. These wireless sensors leverage the tremendous advancements that have taken place in the RF tagging and tracking industries such as packaging and clothing for example.  FIG. 1  shows a commercially available RF tag  10  that sells for less than ten cents per unit. Exemplary RF tags and other equipment used in this system are available from OMEGA Engineering, Inc. Stamford, Conn. 06907-0047. 
         [0022]    These RF tags  10  can be used directly for detection and location purposes or functionalized by integrating them with other sensors  12  such as pH sensors, temperature sensors and the like. Furthermore, unique packaging concepts also allow the tags/sensors to exhibit tailored buoyancy characteristics or surface properties. Conduits, such as pipelines, carry liquid, solid, and/or gaseous mediums from one location to another and are often difficult to inspect, because they are buried beneath the ground. RF tags  10  or sensor pods  14  (functionalized tags), can be introduced into a municipal water system pipeline of interest, for example, for inspection as shown in the schematic illustration of  FIG. 2 . 
         [0023]    As the RF tags  10  and/or sensor pods  14  move down the conduit (e.g., pipeline, cistern, closed channel, etc. . . . ) the population is monitored with one or more transceivers  16  as shown. For breach detection and location, a population of simple RF tags  10  can be employed. Since each tag has a unique ID associated with it, the tag population can be carefully monitored with the transceivers  16  to determine the location of all the tags  10 . If the tag population decreases over a section of conduit, the missing tag population and their individual IDs are noted. This indicates that the RF tags  10  are either accumulating at an obstruction within the conduit, or exiting the conduit through a breach. The time differential between when an RF tag  10  communicates with a first transceiver  16  and a second transceiver  16  can be monitored by a timing device to aid in calculating fluid flow rate. After the population of RF tags  10  has passed a tracking transceiver  16  and some RF tags  10  are noted as missing, an RF tag location system, or pipeline inspection gauge (pig) having a third transceiver  16  may be launched down the section of conduit to locate and pinpoint the exact position of the missing tags  10 . In another embodiment, the transceivers  16  interrogate the missing tags  10  from outside the conduit, either directly affixed to the conduit, or disposed adjacent to or proximate to the conduit. A timing device may monitor the times that an individual RF tag  10  communicates with a first transceiver  16  and a second transceiver  16  for use in calculating fluid flow rates. 
         [0024]    In addition to miniature RF tags  10  described above, functionalized tags, or sensor pods  14  provide the capability to perform measurements for characterizing the fluid in the conduit in real time. Sensor  12  measurements include flow velocity, bulk flow rate, turbidity, pH, and temperature, for example. When RF tags  10  and other sensors  12  are integrated as illustrated in  FIG. 3 , a packaging material is utilized to form an outer casing  18 . Packaging can be formed of plastic material to create an outer casing  18  shaped like a vitamin capsule as shown in the example. The casing  18  halves may be removable or permanently affixed to one another. The packaging adds unique features to the sensor pod  14  including tailored size, buoyancy, and the ability to agglomerate or cluster. Tailored size is useful for differentiating between small and larger breaches as smaller pods  14  may exit through a certain size breach while larger pods  14  will not. With the unique ID that each RF tag  10  contains, the size of the pods  14  that pass through the breach versus those pods  14  that are lodged within the breach can be readily determined. This ability will allow the engineer to effectively approximate the size of a breach in the conduit. 
         [0025]    Tailored buoyancy allows a conduit to be seeded with pods  14  that either travel within the fluid stream (neutral buoyancy), float on the surface of the fluid stream (positive buoyancy), or sink at the bottom of the fluid stream (negative buoyancy). Depending upon the conduit and fluid medium, variable buoyancy may also be of interest as shown in the sensor pod  14  of  FIGS. 4-6 . Variable buoyancy can be achieved by packaging the sensor pod  14  in a manner that includes ballast  20  that dissolves in the fluid over time. The rate at which the ballast dissolves controls the pod&#39;s buoyancy over time. Note that in the embodiment of  FIG. 4 , there is no casing  18  present as in  FIG. 3 . Beginning with negative or neutral buoyancy, the pod  14  may become more positively buoyant as the ballast  20  dissolves ( FIG. 5 ). Alternately, beginning with positive buoyancy, the pod  14  may become more negatively buoyant as the ballast  20  dissolves ( FIG. 6 ). The ballast  20  can be made of any material that is soluble in the fluid itself. A high solubility material will dissolve at a faster rate than a low solubility material and the buoyancy rate will similarly be faster with the high solubility material. Examples of soluble materials for use as ballast  20  include salts, detergents, and sugars. 
         [0026]    It is highly desirable to not only detect and locate conduit breaches but to repair them as well. The package casing  18  may also include the ability for tags  10  and pods  14  to agglomerate or cluster together at a conduit breach, ultimately forming a patch in a similar manner to how blood platelets inhibit blood from escaping the human body at a wound. Several technologies exist that employ polymeric materials to repair a puncture in a vehicle&#39;s tire or a corrosion breach in a refrigeration system. These technologies employ liquid suspensions that act very much like the blood platelet process. In this patent application, the role of the platelets are provided by the tags  10  and pods  14  themselves and the flowing medium would be the fluid flowing in the conduit. 
         [0027]    While this disclosure describes and enables several examples of a conduit breach detection and location system, other examples and applications are contemplated. Accordingly, the invention is intended to embrace those alternatives, modifications, equivalents, and variations as fall within the broad scope of the appended claims. The technology disclosed and claimed herein may be available for licensing in specific fields of use by the assignee of record.