AERIAL PIPELINE SURVEILLANCE SYSTEM

SYSTEME DE SURVEILLANCE AERIENNE DE PIPE-LINE

English Abstract

A method of pinpointing pipeline chemical leaks from an aircraft is disclosed. The method works best when wind speeds are under 10 knots and for liquid chemical leaks when temperatures are above freezing. The method comprises flying the aircraft over the pipeline; continuously collecting an air sample from the exterior of the aircraft; feeding the collected air sample into an air analyzer which tests for high concentrations of the chemical potentially leaking from the pipeline; inputting the output signal from the analyzer to a computer; concurrently inputting a global positioning system receiver output to the computer; programming the computer to correlate the outputs from the air analyzer and the receiver; and checking the correlated output from the computer to locate high concentrations of the chemical and thereby identify pipeline chemical leaks. An apparatus for aircraft surveillance of pipelines is disclosed comprising: an air analyzer to measure concentrations of the potentially leaking chemical connected to an air sample probe outside the aircraft; a computer electrically connected to the output of the air analyzer; and, a GPS receiver electrically connected to the computer. In a preferred embodiment the apparatus further comprises a video camera mounted in the nose of the aircraft, and a VCR in the instrument platform inside the aircraft to monitor the pipeline and surrounding terrain beneath the aircraft to facilitate location of the leaks in the pipeline.

French Abstract

Une méthode pour localiser des fuites chimiques dans un pipeline depuis un avion est divulguée. La méthode fonctionne mieux lorsque les vents sont de moins de 10 nuds et, pour des fuites de produit chimique liquide, lorsque la température est au-dessus de zéro. La méthode consiste à survoler le pipeline par avion; à collecter en continu un échantillon d'air de l'extérieur de l'aéronef; à introduire l'échantillon d'air collecté dans un analyseur d'air qui teste la présence de fortes concentrations du produit chimique susceptible de s'échapper du pipeline; à introduire le signal de sortie de l'analyseur dans l'ordinateur; à introduire au même moment une sortie du récepteur du système de positionnement global dans l'ordinateur; à programmer l'ordinateur pour mettre en corrélation les sorties de l'analyseur d'air et du récepteur; et à vérifier la sortie corrélée de l'ordinateur pour localiser les fortes concentrations du produit chimique et ainsi identifier des fuites chimiques dans un pipeline. Un dispositif pour la surveillance aérienne des pipelines est divulgué, qui comprend : un analyseur d'air pour mesurer les concentrations du produit chimique susceptible de s'échapper connecté à une sonde pour échantillon d'air située à l'extérieur de l'avion; un ordinateur connecté électriquement à la sortie de l'analyseur d'air; et un récepteur GPS connecté électriquement à l'ordinateur. Dans un mode de réalisation préféré, le dispositif comprend en outre une caméra vidéo montée dans le nez de l'avion et un magnétoscope dans la plate-forme de l'instrument à l'intérieur de l'avion pour surveiller le pipeline et le terrain environnant situé sous l'avion afin de faciliter la localisation des fuites dans le pipeline.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of aircraft surveillance of pipelines for chemical leaks
comprising the following steps:
flying the aircraft over the pipeline;
continuously collecting an air sample from the exterior of the aircraft;
feeding the collected air sample into an air analyzer which tests for
high concentrations of the fluid potentially leaking from the pipeline;
inputing the output signal received from the analyzer to a computer;
concurrently inputing a GPS receiver output to the computer;
programming the computer to correlate the outputs from the air
analyzer and the receiver; and
checking the correlated output from the computer to locate high
concentrations of the chemical and thereby identify pipeline chemical leaks.
2. A method as in claim 1 wherein the analyzer is set up to output only
differences between chemical concentrations in the sample air in ambient air.
3. A method as in claim 2 wherein the computer includes a hard drive,
and the computer is programmed to store the correlated outputs on the hard
drive.
4. A method as in claim 3 wherein the computer includes a monitor and
the computer is programmed to graphically display the correlated outputs on
the
monitor.
5. A method as in claim 4 wherein the computer is programmed to
produce an audio signal wren the measured relative concentration exceeds a
predetermined level.

6. A method as in claim 2 further comprising a video camera monitoring
and a VCR recording of the pipeline and surrounding terrain beneath the
aircraft.
7. A method as in claim 6 wherein the air analyzer output is mixed with
the video camera output prior to the video cassette recording.
8. A method as in claim 6 wherein the GPS output is also mixed with
the video camera output prior to video cassette recording.
9. A method as in claim 2 wherein the air analyzer is a hydrocarbon
analyzer.
10. An apparatus for aircraft surveillance of pipelines for finding chemical
leaks comprising:
an air analyzer to measure concentrations of the potential leaking
chemical;
an air sample probe to collect air from outside the aircraft;
a tube having one end connected to the air sample probe and the
other end connected to the air analyzer to conduct sample air drawn from
outside
the aircraft to the air analyzer;
a computer electrically connected to the output of the air analyzer;
and
a GPS receiver electrically connected to the computer.
11. An apparatus as in claim 10 wherein the air analyzer is set up to
output only differences between chemical concentrations in the sample air and
in
ambient air.
12. An apparatus as in claim 11 wherein the air analyzer is equipped with
a pump to increase the velocity of air received from the air sample probe.

13. An apparatus as in claim 12 wherein the computer includes a hard
disk, and the computer is programmed to correlate data inputs received from
the
GPS receiver and the air analyzer outputs said correlated data to the hard
disk for
storage.
14. An apparatus as in claim 13 wherein the computer includes a monitor
and the computer is programmed to graphically display the correlated data on
the
monitor.
15. An apparatus as in claim 11 wherein the computer is programmed to
produce an audio signal when the measured relative chemical concentration
exceeds a predetermined level.
16. An apparatus as in claim 11 further comprising a video camera and a
VCR to monitor the pipeline and surrounding terrain beneath the aircraft.
17. An apparatus as in claim 16 wherein the air analyzer output is mixed
with the video camera output prior to video cassette recording.
18. An apparatus as in claim 17 wherein the GPS output is also mixed
with the video camera output prior to video cassette recording.
19. An apparatus as in claim 11 wherein the air analyzer is a
hydrocarbon analyzer.

Description

2~7s~s~
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AERIAL PIPELINE SURVEILLANCE SYSTEM
BACKGROUND OF THE I2JVENTION
This invention relates to detection of chemical leaks in
pipelines. More particularly this invention relates to
detection from an aircraft of such chemical leaks.
The problem of locating leaks of chemicals in pipelines
has been a problem existent since such chemicals were transported
in pipelines. The laborious method of testing ground air
samples taken along the length of a pipeline and looking for dead
vegetation in summer still offers advantages to state of the art
infrared systems.
In an infrared system heat dissipated by the leaking
chemical is searched for by an aircraft. The problem with an
infrared system is that it yields poor results if the leak is
small, on the underside of a pipeline, if the pipeline is
submerged in water, or where the pipeline is surrounded by
vegetation. Another limitation of this technology is the length
of time required to develop an image. Recent environmental
legislation creates demandifor a more effective means of locating
chemical leaks in pipelines.
It is an object of this invention to disclose a more
effective means of detecting a chemical leak from a pipeline.
It is an object of this invention to disclose a system which can
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more quickly and inE~xpensively, pinpoint the location of small
leaks previously unperceptible from a fast moving aircraft. It
is yet a further ob=ject of this invention to disclose a data
storage and retrieval method and apparatus which allows fast
access and physical identification of problematic points along a
system of pipelines.
One aspect of this invention provides for a method of
aircraft surveillance of pipelines for chemical leaks comprising
the following steps: flying the aircraft over the pipeline;
continuously collecting an air sample from the exterior of the
aircraft; feeding t:he collected air sample into an air analyzer
which tests for high concentrations of the chemical potentially
leaking from the pipeline; inputing the output signal from the
analyzer to a computer; concurrently imputing a GPS receiver
output to the computer; programming the computer to correlate
the outputs from the: air analyzer and the receiver; and checking
the correlated output from the computer to locate high
concentrations of the fluid and thereby identify pipeline
chemical leaks. In one aspect of this invention the computer is
programmed to graphically display the correlated outputs on its
monitor, in another aspect of this invention a video camera
monitors and a VCR records the pipeline and surrounding terrain
beneath the aircraft.
An apparatus to perform the above described method is
provided. A preferred aspect of this apparatus provides for an
air analyzer which is set up to output differences between
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chemical concentrations in the collected air sample and the
ambient air. This rep>ults in a focus on the pipeline, rather
than on high levels of: chemicals in the background generated from
other sources.
Various other objects, advantages and features of this
invention will become apparent to those skilled in the art from
the following description in conjunction with the accompanying
drawings.
FIGURES OF THE INVENT7:ON
Figure 1 is a perspective view of a schematic diagram
of the aerial pipeline: surveillance system.
Figure 2 is a graphical summary of results taken along
a length of pipeline.
The following is a discussion and description of the
preferred specific embodiments of this invention, such being made
with reference to the drawings, wherein the same reference
numerals are used to indicate the same or similar parts and/or
structure. It should be noted that such discussion and
description is not me~~nt to unduly limit the scope of the
invention.
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DESCRIPTION OF THE I1VVENTION
Turning now to the drawings and more particularly to
figure 1 we have a s~~hematic diagram of the Aerial Pipeline
Surveillance System :20, hereinafter referred to as the APSS.
The APSS 20 is housed in the nose baggage compartment of an
aircraft 26. It ha;s been found that both the Piper Seneca and
the Navajo twin engine aircraft have adequate room to house the
APSS 20, two pilots and a systems operator. Two pilots are
required because the aircraft 26 is usually flown at the high
stress altitudes of less than two hundred feet above ground and
at speeds of about one hundred knots.
The APSS 20 comprises a sample probe 22 and an optional
video camera 24 which is housed in the nose baggage compartment
of the aircraft 26. The video camera 24 sees outside through a
plexiglass aperture 23 in the nose baggage compartment of the
aircraft 26. The sample probe 22 is a half inch diameter
stainless steel pipe which extends 18 inches into the undisturbed
air beyond the aircraft 26 nose. It is made of stainless steel
to minimize hydrocarbon absorption. The video camera 24 is
positioned to display about a 30 degree view of the flight path.
The APSS 20 also comprises an instrument platform 30 and a tube
28 extending thereto from the sample probe 22. The instrument
platform 30, housed in the cabin of the aircraft 26 measures 3.5
ft wide by 2.5 ft high by 2.5 ft deep and weighs less than 200
pounds. The instrument platform 30 comprises an air analyzer
32 which most typically is a hydrocarbon analyzer 32
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aerodynamically connecaed to the sample probe 22 by the tube 28,
and a computer 34 which receives inputs from the hydrocarbon
analyzer 32 and a global positioning system (GPS) 33; and,
outputs to a video recorder 36 which is connected to the video
camera 24.
A continuous; stream of air flows through the air sample
probe 22 at a high speed. A portion of this air stream, the air
sample 21 is drawn through the tube 28 to the air analyzer 32
where it is measured continuously for changes in chemical content
relative to previously drawn air samples 21. This relative
chemical air content measurement of the air sample 21 is inputed
to the computer 34 in a digital form (some chemical analyzers 32
output a digital signal, others output an analog signal which
must be subsequently converted to a digital signal). The
computer 34 is also fe:d an input from a global positioning system
(GPS) 33 which outputs. exact longitudinal and latitude
coordinates determined from satellite signals every two seconds.
The computer 34 is programmed to correlate the chemical content
in the air measurements read every half second with the GPS 33
coordinates received every two seconds. The computer 34 stores
this correlated data an its hard drive.
Alternatively, or additionally the GPS 33 and chemical
content data may be outputted through a video mixer 35 to the
video recorder 36 where it may be recorded concurrently with the
view of the pipeline a.nd surrounding terrain so that the video
cassette recording contains a complete record of the longitude

21 X6065
and latitude, the local terrain and landmarks, and associated
relative chemical level. The monitor of the video recorder 36
allows the system operator to view the pipeline (not shown) as it
is travelled and identify any obvious chemical sources such as
farming feedlots, compressor stations, valves etc. (all not
shown). The video may be later reviewed to try to identify any
chemical anomalies that were revealed by the analysis of the data
that were not readily apparent during the survey. As well, the
video is useful when planning the logistics of responding to
maintenance or repair of the leak site.
Where a known leak is being searched for, it is also
useful to output the computer 34 data live to its monitor
together with an audible alarm signalling relatively high
chemical content. The computer 34 used is a DOS based laptop. A
software program was written to capture and organize output data
in an ASCII text file protocol. The program has defaults which
can be changed to accommodate alternate file names, sample speeds
and other communications parameters. With the use of the ASCII
data file the output data is then able to be plotted using a
popular off the shelf land survey drafting program such as
Autocad T.M. by Autodesk Inc. Figure 2 shows a printed 3-D
graphical image of relative chemical measurements taken every
half second, correlated with longitude and latitude coordinates
taken every two seconds. The difference between the chemical
content in the air sample 21 drawn from outside the aircraft 26
and previous readings thereof is what is plotted. Addition of
artificial zero gas data points
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are installed a few :hundred feet on either side of the pipeline
(not shown). This 'results in a focus on the pipeline (not
shown) and not on high levels of hydrocarbons in the background
generated from other sources.
The APSS 20 will operate with different hydrocarbon
analyzers 32 currently available; however, the AE 2420 analyzer
manufactured by Airwave Electronics Ltd. in Calgary, Canada is
preferred for its sensitivity, a five second response time (to
read 90% of signal strength), high reliability, and low
maintenance. This analyzer 32 has improved temperature
stability, and radio frequency interference reduction. Response
time is critical.with taking measurements in an aircraft 26
flying at 100 knots. This analyzer 32 employs an external
vacuum pump (not shown) to draw sample air 21 into its detector
(not shown). The analyzer 32 outputs an analog signal accurate
to less than .1 ppm 'which is proportional to the concentration of
hydrocarbons present in the sample air 21. The analyzer 32 is
setup to output the difference between hydrocarbon concentrations
in the sample air 21 and prior measurements taken thereof.
Typically the aircraft 26 is only in the leak plume for 1-3
seconds and there is insufficient time to achieve 100 percent
instrument response to the elevated hydrocarbon levels.
However, it is only necessary to qualitatively identify a larger
than background hydrocarbon anomaly to determine the presence of
a potential leak source. Response time, not accuracy is the
critical issue. None the less, prior to each use of the
analyzer 32, it is recommended that the analyzer's calibration be
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a
verified with a known concentration of chemical to verify proper
operation.
The APSS 20 may also utilize different types of air
analyzers 32. Airwave Electronics Ltd. of Calgary, Canada has a
model Flame Photomei:ric Sulfur Analyzer which has a fast response
time and is suitable: for the monitoring of sulfur dioxide or
other sulfur gases.
Optimal weai~her conditions for pipeline surveillance are
when wind speed is under 10 knots. When surveilling a pipeline
carrying liquid petroleum it is preferable to operate in above
freezing weather since warmer temperatures are required to
promote a suitable evaporization rate in order to yield a well
defined plume. Te:~ts have shown clearly defined detection of
natural gas released at a rate of 1 cfm with a 5 knot wind. In
another test 20 gal:Lons of fuel, placed in a 100 square foot
shallow pan at free;aing temperatures with a 10 knot wind, was
clearly pinpointed.
The APSS 20 is a commercial success. In its first
months of use more 'than ten thousand miles of transmission
systems have been s~srveyed, in typically less than 10 percent of
the time and with a few percent of the labor, previously expended
for the surveillance thereof.
While the invention has been described with preferred
specific embodiments thereof, it will be understood that this
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s
description is intended to illustrate and not to limit the scope
of the invention, wh:Lch is defined by the following claims.
I CLAIM
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Representative Drawing