Detection of leaks in vessels

• US 5,675,506 A
• Filed: 02/10/1995
• Issued: 10/07/1997
• Est. Priority Date: 10/09/1992
• Status: Expired due to Fees

• Current Assignee: Rensselaer Polytechnic Institute
• Original Assignee: Rensselaer Polytechnic Institute
• Inventors: Savic, Michael
• Primary Examiner(s): Ramirez, Ellis B.
• Assistant Examiner(s): Stamber, Eric W.
• Application Number:
  US08/386,962
• Time in Patent Office: 970 Days
• Field of Search: 364/509, 364/510, 73/40, 73/40.5 A, 73/40.5 R, 73/49.1, 73/49.2, 73/592, 340/605
• US Class Current: 702/51
• CPC Class Codes: F17D 5/06 using electric or acoustic means
• CPC Class Codes: G01M 3/007 Leak detector calibration, standard leaks G01M3/207 takes precedence
• CPC Class Codes: G01M 3/24 using infrasonic, sonic, or ultrasonic vibrations
• CPC Class Codes: G01M 3/243 for pipes

Abstract

An apparatus and process for determining the existence and location of a leak in a vessel such as a container or an above ground or underground pipe, comprises a plurality of remote acoustic transmission sensor units distributed along the pipe and each containing equipment for analyzing acoustic signals from the pipe. The equipment includes a mechanism for identifying acoustic features of the acoustic signals which distinguish the acoustic signals of a leak from ambient acoustic signals. A control unit is connected to each of the remote units and includes additional equipment for further analyzing the signals to determine the proximity of the signal to a particular remote unit and, using the amplitude of the signal and the transmission characteristics of the pipe, determining the location of the leak.

Claims

1. A method for locating a leak in a vessel which has an acoustic transmission line characteristic, comprising:

placing at least one remote acoustic signal transducer at a selected location adjacent the vessel for converting acoustic signals from the vessel into an electric signal in the transducer;

continuously transmitting the electric signal to a central processing station;

providing transducer location information and the acoustic transmission line characteristic of the vessel, to the central processing station;

identifying acoustic features of an acoustic signal generated by a leak in the vessel using cepstrum analysis at the central processing station, to identify the acoustic features;

extracting from the electric signal, cepstrum coefficients;

detecting the existence of a leak in the vessel by subjecting the electric signal to pattern recognition analysis using the cepstrum coefficients to determine the presence of the acoustic features in the electric signal, the presence of the acoustic features indicating the presence of a leak in the vessel; and

using the acoustic transmission line characteristic of the vessel to locate the leak in the vessel, with respect to the transducer which is at the selected location.

2. A method according to claim 1, including placing a plurality of acoustic signal transducers at spaced selected locations along the vessel, each for converting acoustic signals from the vessel into electric signals, the method including identifying two adjacent spaced selected locations at which the electric signals containing the acoustic features have greatest amplitude, the leak in the vessel being between the two adjacent spaced selected locations.

3. A method according to claim 2, wherein the vessel is an elongated above ground pipeline.

4. A method according to claim 3, wherein the pipeline carries pressurized gas.

5. A method according to claim 3, wherein the pipeline carries pressurized liquid.

6. A method according to claim 1, wherein the vessel is a container containing gas or liquid under pressure.

7. A method according to claim 1, wherein the cepstrum analysis is a linear predictive coding analysis.

8. An apparatus for detecting a leak in a vessel having an acoustic transmission line characteristic, comprising:

at least one remote acoustic transducer at a selected location along the vessel, responsive to acoustic energy from the vessel at the selected location, to generate an electric signal in the transducer;

a central processor remotely located from the transducer and containing data about the acoustic transmission line characteristic for the vessel and data describing acoustic features of an acoustic signal generated by a leak in the vessel;

the central processor also including program and analysis means and being operatively connected to the transducer, the program means subjecting the electric signal to pattern recognition analysis to determine the presence of the acoustic features in each signal using cepstrum coefficients, the presence of the acoustic features indicating the presence of a leak in the vessel and thus detection of the leak, the program means also using an attenuation of an amplitude of the electric signal containing the acoustic features to locate the leak with respect to the selected location of the transducer using the acoustic transmission line characteristic of the vessel.

9. An apparatus according to claim 8, wherein the vessel is a container containing gas or liquid under pressure.

10. An apparatus according to claim 8, wherein the vessel is an elongated pipeline above the ground.

11. An apparatus according to claim 10, wherein the elongated pipeline contains pressurized gas.

12. An apparatus according to claim 10, wherein the elongated pipeline contains pressurized liquid.

13. An apparatus according to claim 8, including a plurality of remote acoustic transducers, each at a selected location along the vessel, a control unit connected to each transducer, at least part of said program and analysis means being in said control unit for identifying two adjacent selected locations at which the electric signals containing acoustic features have greatest amplitude and for calculating a distance of the leak in the vessel from at least one of the adjacent transducers, as a function of the acoustic transmission line characteristic of the vessel.

14. An apparatus according to claim 13, wherein each remote acoustic transducer is engaged to the vessel for receiving acoustic signals from the vessel, analog-to-digital conversion means connected to each transducer for converting analog acoustic signals from the transducer into digital acoustic signals, memory buffer means connected to the analog-to-digital conversion means for storing the digital signal and control logic means connected to the analog-to-digital conversion means and the memory buffer means for transmission of sampled digital analog signals to the program and analysis means.