INFRARED REMOTE MONITORING SYSTEM FORLEAK
CROSS-REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of application serial number 08/770,365 filed November 29,
1996, now allowed.
INTRODUCTION
This invention relates to a method and apparatus for the measurement of hydrocarbon gases and hydrocarbon
related toxic gases and vapors in ambient air. More
particularly, this invention relates to a method and
apparatus for the measurement of such gases by way of
infrared technology combined with an airborne or moving ground based platform.
BACKGROUND OF THE INVENTION
The use of infrared technology to determine the
presence or absence of hydrocarbons in ambient air is known.
Such methods position the technology adjacent the area of
interest and the receiver and transmitter are fixed in place at the location. Such location may, for example, be near a
pipeline which is carrying such gases or in a storage area where such gases are stored for processing or where they may
be transferred. The presence of such gases indicates
leakage and steps can then be taken to remedy the situation.
The use of an airborne or ground based moving
platform for mounting instrumentation is also known. Such
instrumentation may utilize a locator device to determine
the precise position of the platform relative to the ground
and the instrumentation will provide information which is
referenced to the known position. Typically, such
instrumentation as cameras, thermal imaging and the like, have been used on airborne platforms .
Infrared technology has, however, not been used on
an airborne or ground based moving instrument platform for
pipeline surveillance and the use of such technology has
many advantages. Presently, visual identification to
identify pipeline leakage relies on an identification of
dead vegetation to identify leak sources and is limited to
the summer and areas with sufficient green vegetation during
those periods . In rared thermographic evaluations compare temperature differences between an oil or gas leak compared
to the environmental surroundings. The thermographic technique requires relatively lengthy time periods to
develop a thermographic image and does not work well in cold
climates or in areas with a significant vegetation canopy.
A flame ionization (FID) analyzer to evaluate ambient air
for hydrocarbon gases/vapors utilizes relatively small
samples . Thus , if the aircra or ground based vehicle is
moving quickly, the sample may not be representative and the
lag time until the same enters the FID analyzer is lengthy.
Likewise, the flame ionization instrument requires compressed hydrogen gas in order to operate . This presents
a significant explosive and flammable hazard particularly
where the aircraft is flying fast and low and where the
ground based vehicle may be operated in urban areas .
SUMMARY OF THE INVENTION
According to one aspect of the invention, there is provided apparatus to measure predetermined gases present between an infrared transmitter and an infrared receiver
mounted on a movable platform, means to measure the quantity
of predetermined gases present in the area between said
infrared transmitter and said infrared receiver and means to
correlate the measurement of said predetermined gases present between said infrared receiver and said infrared
transmitter and the geographic location of said movable
platform.
According to a further aspect of the invention, -
there is provided a method of measuring predetermined gases
present between an infrared transmitter and an infrared
receiver, said method comprising emitting infrared radiation
from said infrared transmitter, said infrared transmitter
being located on a movable platform, receiving a portion of
said emitted radiation in said receiver from said
transmitter located remotely from said infrared transmitter,
determining the quantity of said predetermined gases present
between said infrared transmitter and said infrared
receiver, and correlating the measurement of said
predetermined gases by said receiver and transmitter to said
geographic position of said movable platform.
According to yet a further aspect of the
invention, there is provided a method to obtain information
concerning charge characteristics of a cathodic protection
device associated with a pipeline and having a transceiver
and circuitry associated therewith, said method comprising
being a vehicle into proximity and line of sight view with
said cathodic protection device, interrogating said
transceiver of said cathodic protection device from said
vehicle, receiving data transmitted from said transceiver of
said cathodic protection device and maintaining said
received data on said vehicle.
According to still yet a further aspect of the
invention, there is provided apparatus to interrogate a
cathodic protection device associated with a pipeline, said
apparatus comprising a transceiver operably associated with said cathodic protection device and being operable to
transmit charge data associated with said pipeline, a power
source to supply electrical power to said transceiver and an
integrator to interrogate said transceiver and to receive data transmitted from said cathodic protection device.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
Specific embodiments of the invention will now be
described, by way of example only, with the use of drawings
in which:
Figure 1 is a diagrammatic illustration of an open
path infrared detection system mounted on a movable airborne
platform according to the invention;
Figure 2 is a diagrammatic view of a flow through
infrared detection system according to a further aspect of
the invention;
Figure 3 is a diagrammatic view of the open path
configuration utilising a White cell technique within a tube
of the instrument, the White cell technique being used to
increase the optical path of the infrared beam;
Figure 4 is a diagrammatic view of the open path
infrared detection system mounted on a ground based movable platform positioned on a vehicle;
Figure 5 is a diagrammatic view of an open path infrared detection system mounted on an movable airborne plat orm in a location different from the location
illustrated in Figure 1 and further utilising a single instrument body including a tube;
Figures 6A and 6B illustrate a methane "spike"
obtained from the simulated operation of the movable
airborne platform and the actual operation of the movable
ground based platform, respectively, the two "spikes"
representing an unusual condition at the geographical
locations noted;
Figure 7 illustrates the infrared detection system
mounted on a fixed wing aircraft;
Figure 8 illustrates an enlarged view of the instrument of Figure 5 ;
Figure 9 is a diagrammatic aerial view of a
pipeline with a cathodic protection station located adjacent thereto according to a further aspect of the invention;
Figure 10 is an enlarged side view of the cathodic protection station on Figure 9;
Figure 11 is a diagrammatic view of an airborne vehicle used for transmitting and receiving data from the
cathodic protection station; and
Figure 12 is a view of a guidance array used to
direct the aircraft more closely to the cathodic protection
station.
DESCRIPTION OF SPECIFIC EMBODIMENT
The infrared sensor and locator system is
generally illustrated at 10 in Figure 1. It comprises an
infrared transmitter 11 and an infrared receiver 12 , each of
the receiver 12 and transmitter 11 being mounted on an
airborne platform conveniently in the form of a helicopter 13. The transmitter 11 and receiver 12 could, for example, be mounted on the skids 16, 17 of the helicopter 13. The
transmitter 11 and receiver 12 are positioned below the body
of the helicopter 13 and are located a certain distance apart in an open path configuration. The spectrum which
results from the transmitted infrared radiation is gathered
in the infrared receiver 12 and passes to the data
acquisition system 15. The spectrum reflects the identity
of gases present between the transmitter 11 and receiver 12
and, if the gases present are known, the quantity of such
gases present may also be determined.
The helicopter 13 also has a global positioning
system ("GPS") 14 operably connected to the data acquisition
system. As information is obtained from the receiver 12,
the quantity of gases is correlated with the position of the
airborne plat orm 13. Thus , the position of any
contaminating emissions measured by the receiver 12 will be
quickly known and other units can be dispatched to that
location either to repair or to shut in the emission.
The optical path of the infrared beam is illustrated in Figure 3. A "White cell" generally illustrated at 30 comprises a chopper wheel 31 which rotates to allow only a narrow beam 32 to pass therethrough as
illustrated. The beam 32 is reflected between mirrors 33, 34 so as to increase the length of the open path within which the ambient air is analyzed. By increasing the length of the open path, the sensitivity of the instrument increases since the detection limit is inversely proportional to path length. Thus, if the infrared beam 32 is reflected through the air sample, conveniently forty (40) times, an approximate forty (40) fold improvement in sensitivity is obtained. Other multiples are available as may be desired by the user.
The infrared (IR) light 32 generated by an IR source (not illustrated) enters the White cell 30. The IR
light passes between the field mirror 34 and objective mirrors 33 many times, conveniently in the case of methane, forty (40) times. The White cell 30 is open to the sample air, which may or may not contain methane or other analyte gases. The IR light 32 exits the White cell 30 and passes
through a four segment optical chopping wheel 31. Two
segments of the wheel are opaque to all infrared radiation,
one segment being an IR transparent cell containing methane
and the fourth segment being an IR transparent cell
containing nitrogen. After passing through the optical
chopping wheel 31, the IR light 32 is split into two beams
by an IR beam splitter 42. One of the beams passes through
a 3.31 micrometer optical bandpass filter and the intensity of the transmitted beam is measured by detector 44. The second beam passes through a 3.89 micrometer optical
bandpass filter and the intensity of the transmitted beam is
measured by detector 43.
The methane concentration is proportional to the
ratio of the intensity measured by detector 44 when the
nitrogen segment of optical chopper 31 is in the light beam.
The concentration of total hydrocarbon is proportional to the intensity of light measured by detector 44 to the
intensity of light measured by detector 43, both taken when the nitrogen segment of optical chopper 31 is in the light
beam.
An alternative or "flow through" infrared detection systems is illustrated in Figure 2. In this
embodiment, the helicopter or airborne platform 20 includes
a probe 21 which extends from the forward end of the
helicopter 20. The probe 21 is typically of stainless steel
and has an inside diameter of approximately 1/2 inch. The gas (not illustrated) enters the open end of the probe 21
and passes to a flow through infrared analyzer 22 through
inlet 23. A data acquisition system 24 is operably connected to the infrared analyzer 22 and a GPS 25 is
operably connected to the data acquisition system 24 so, as described earlier in connection with the open path infrared
detection technique, the geographic location of the airborne
platform 20 together with the aircraft speed, time of day and altitude will be known according to the data obtained by
the data acquisition system 24 in the analyzer 22.
OPERATION
In operation, the helicopter 13 will be flown near
an area where potential leakage of hydrocarbon gases may
occur. The airborne platform, be it the helicopter 13 or a
fixed wing aircraft 70 (Figure 7) will typically be operated
at a speed of 50 to 100 miles per hour and at an altitude of
50 to 100 feet. Such an area of operation would typically
encompass an oil or natural gas or natural gas liquid
pipeline and such gases would typically be hydrocarbon
emissions due to leakage in the aforementioned pipelines .
The operation of the infrared transmitter 11 and
infrared receiver 12 is initiated together with the data
acquisition system and the global positioning system ("GPS") 15.
As the helicopter 13 proceeds down its assigned flying corridor, gases will be present in the atmosphere and
the infrared detection system 10 will be programmed so as
only to respond to those gases which it is desired to detect
as has been described. When such gases are detected, the
quantity of such gases will be determined and this amount
will then be stored in the data acquisition system 15 and
correlated with the geographic position of the instrument
platform of the helicopter 13 as determined by the GPS 14'.
When the helicopter 13 has reached the end of its
route and has returned to its operating base, the
information on the data acquisition system 15 will be
downloaded and reviewed for any predetermined gases present,
such as methane, and their amount. If such gases are
detected and the quantity of such gases are of concern,
remedial action can be taken to determine the source of the gas and how to reduce or terminate its presence.
For example, and with reference to Figures 6A and
6B, spikes 50, 71 have been detected which clearly stand out
from the usual concentration of methane in the atmosphere as shown generally at 54, 72, respectively, as degrees of
longitude are traversed by the helicopter 13 as shown on the abscissa of the plot. The latitude and longitude of the
location of the spike 50 is recorded by the GPS and illustrated at 56. The location of the spike 72 in Figure
6B is shown at 73. The weather conditions under which the
aircraft 13 was operating are also provided at 55 in Figure
6A. Thus, remedial and service units can be deployed to the
proper position to determine the cause of the spikes 50, 72.
Figure 6A was obtained in a simulated test using an open
valve with an airborne helicopter using the infrared
detection system. Figure 6B was an actual occurrence and
was obtained using a movable platform on a ground based vehicle .
The "open path" analyzer 10 of Figures 1 and 5 can constantly analyze a large representative sample of the gases present in the atmosphere. A sample rate of
approximately 3000 liters/second is contemplated. The "flow
through" analyzer illustrated in Figure 2 is a lower rate
sampler, typically about 500 to 1000 cubic centimeters/ in.
Many modifications will readily occur to those skilled in the art to which the invention relates . For
example, rather than an airborne platform on a helicopter
13, the airborne platform 80 could be mounted on the fixed
wing aircraft 72 (Figure 7) with the instrument 81 attached
thereto . Likewise, although the primary area of application
will be in the evaluation of hydrocarbon gases/vapors, the
technology is also applicable to detect other such gases as
carbon dioxide, carbon monoxide, sulfur dioxide, ammonia or
other analyte gases as the user may desire.
A further embodiment of the invention is
illustrated in Figure 4 in which a ground based moving
platform, namely a truck or vehicle generally illustrated at
51, has the infrared detection system generally illustrated
at 52 mounted on the forward end of the vehicle 51. The GPS
acquisition system 53 is located in the interior of the
vehicle 51. The use of the GPS acquisition system 53 on the vehicle 51 is most useful only in rural and sparsely settled areas which, of course, is where many miles of pipelines and other surface facilities are located. However, if the area
of interest is located in an urban area, the GPS system 53 suffers from accuracy problems due to the difficulty in
obtaining line of sight between the plurality of satellites providing triangulated input parameters to the GPS system
because of the presence of buildings, trees, tension lines
and the like. For this reason, it may be desirable to use a
dead reckoning technique under these conditions . The dead
reckoning technique may typically use city maps , compass
means , speedometer means and/or a measuring wheel and the
like .
Yet a further embodiment of the invention is
illustrated in Figure 5. An airborne platform, conveniently
a helicopter 60 , will have an infrared detection system 61
mounted on platform 62 similar to the embodiment of Figure
1. However, whereas the receiver 12 and transmitter 11 of
the infrared detection system 10 of Figure 1 were mounted on
opposite skids 16, 17 of the helicopter 13 and do not
utilise a self-contained instrument with a tube 84 (Figure 8) , in the Figure 5 embodiment the receiver (not
illustrated) and transmitter (not illustrated) are both
mounted on the same platform 62 in a single instrument 61
attached to skid 63. The skids 63, 64 of Figure 5 and the
skids 16, 17 of the helicopter 13 in Figure 1 are typically hydraulically mounted so as to more sof ly impact the ground
when landing. During that period, there is relative
movement between the transmitter 16 and receiver 12 of the Figure 1 embodiment since they were mounted on different
skids 16, 17. By mounting both the receiver and transmitter of the infrared detection system 61 on the same skid 63 as
shown in the Figure 5 embodiment, such relative movement is
removed which allows greater integrity in calibrating and
setting the instrument up for operation.
Whereas the analysis of the data obtained by the
data acquisition system has been previously described as
being downloaded for processing and analysis , it would be
desirable to transmit the data obtained directly to a processor located remotely from the data acquisition segment
for real time processing and review by a remotely located
operator . This would be desirable under certain conditions
where analysis was required as early as possible .
Alternatively, an operator on the aircraft or vehicle could
identify anomalies concurrent with its acquisition.
While the White cell technique previously
described covers principally methane, the measurement
technique can be extended to other gases by changing the
wavelengths of the optical bandpass filters in front of
detectors 43, 44 (Figure 3) and. by changing the gases in the
IR transparent segments of the optical chopping wheel 31.
A further aspect of the invention relates to
obtaining charge readings from cathodic protection device .
Cathodic protection devices provide a charge to various
metallic structures which are operably positioned within the
ground. Such structures include pipelines, cathodic
protection anodes , re erence cells , recti iers or other
power sources , casings , storage tanks and the like . The use
of cathodic protection increases the life of such
components , the requirements generally being dictated
according to the local soil conditions where such metallic
structures are located and it is necessary, from time to
time , to monitor the charge readings to ensure that the
charge is being properly transferred to the metallic structure so as to prevent deterioration of the structure and that the charge is appropriate for the soil conditions which may change from time to time .
Heretofore, the readings of such cathodic test
stations were generally obtained by one or a combination of
three techniques . In a first technique , the readings were
obtained manually by a team or individual who travelled to the site of the cathodic test station by foot, ATV vehicle or otherwise. The readings from the terminal board mounted
on the cathodic test station were taken with instrumentation carried by the operator and then analyzed. The difficulties
associated with the technique included the fact that many
test stations are located in remote locations where travel
is only possible during certain seasons. Likewise, the cost
and time associated with the manual instrumentation reading
technique are substantial.
A second technique for taking the readings is by
way of a cellular phone or other wireless radio technique. This method interrogates the test station and the data is
subsequently transmitted to the nearest antenna operably
associated with the cellular phone or wireless radio and
test station. The antenna may be located some distance from
the test station and the power requirements for the transmission of data from the test station are significant.
If the power is supplied from a battery, the battery must be
periodically recharged which may well be inconvenient and,
in any event, is costly. Otherwise, a reliable local power
supply is necessary which may not be available in such a
remote location. For practical . purposes , therefore, the
technique is restricted to rectifier facilities or local
plants where such power facilities are available.
A further or third technique utilizes low earth
orbit satellite networks or AMSC . The test stations are
interrogated when the satellite is overhead and the charge
data is subsequently transmitted to the satellite. Again,
the power required for such transmission from the test
stations limits the use of such techniques to plant and rectifier facilities where reliable local power is
available. Further, sophisticated and expensive hardware is
required for the satellite interrogation and transmission
technique .
The further embodiment of the invention is illustrated in Figures 9, 10, 11 and 12 which relate to the interrogation of cathodic test station locations . In this
embodiment, a cathodic protection monitoring station is generally illustrated at 100. It takes the form of a
cylinder and is located besides and above pipeline 101. It
is buried within the ground 105 adjacent to the pipeline 101
to a distance of approximately one-half its length as seen
in figure 10. Cathodic protection station 100 is wired to receive charge and electrical data from the pipeline 101 or
other metallic structure so that the condition of the charge
flowing from or to the pipeline 101 may be obtained from
appropriate terminals located beneath a plastic cap 110 on
the test station 100 which is used to protect the terminals
and the associated components and circuitry from adverse
weather operating conditions and so that other cathodic
protection data can be obtained and accessed.
The cathodic protection requirements for pipelines
are generally defined by the companies operating the
pipeline, which regulations or operating requirements are
dictated by the particular soil or other conditions to which
the pipeline 101 is subjected. These requirements include
the application of cathodic protection to effective reduce
corrosion of the pipeline or other metallic structure. This
information is important and must be monitored regularly.
A TAG or smart card 111 is mounted at the cathodic
protection station 100 and receives and stores electrical
data from pipeline 101. The smart card 111 also holds data indicating the identity and geographic location of the cathodic protection station 100, the location of the
catnodic protection station 100 being compared with the
location as given on a GPS locator device as will be
described.
A low power transceiver 112 is located at the
cathodic protection station 100 and may be integrated with
the smart cad 111. The low power transceiver 112 is
conveniently powered by a longlife battery, such as a
lithium battery 113 which is intended to provide power fox
transmitting data for a very short distance, approximately 200 feet or so. By operating in this manner, the lithium
battery 113 has a relatively long life and need only be
replaced at fairly long intervals.
An airborne vehicle, conveniently a helicopter 114 contains an integrator 115, an antennae 116, a GPS locator
device 117 and associated circuitry which will interrogate
the transceiver 112 and/or smart card 111 at the cathodic
protection station 100 and receive the data transmitted from
the transceiver 112 when it is interrogated. The integrator
115 will store the received data and download it for
analysis when convenient to do so or, alternatively, it may be shown real time in the helicopter 114 so that any
servicing can be performed at the same time the vehicle 114
is adjacent the station 100.
A guidance array 120 is located within the
aircraft 114 (Figure 9) . The guidance array 120 provides a
plurality of light emitting diodes 121 located generally
transverse to the line of sight of the pilot of the aircraft
114. As the aircraf 114 approaches the location of the
cathodic protection station 100, the integrator 115 will
interrogate the cathodic protection station 100 as to its
location. A beacon or other homing device at the cathodic
protection station 100 will provide the necessary guidance
to the array 120 and will act similarly to an aircraft
transponder to provide data to the LED' s 121 thereby
indicating the proper position of the cathodic protection station 100 relative to the aircraft 114. This will allow
more accurate navigation by the pilot and reduce power
requirements for data transmission. It is intended that the
data received from the cathodic protection station 100 be
transmitted to aircraft 114 when the aircraft 114 is within
500 feet of the station 100 and, preferably, within 200 feet of the station 100.
In operation, the pilot of the aircraft 114 will fly the route of the pipeline 101. He will periodically
interrogate the various cathodic protection stations 100
located intermittently along the pipeline route using
integrator 115 and direct the aircraft 114 to a location
close to each cathodic protection station 100 by using
guidance array 120. When each location is reached, the
transceiver 112 of the cathodic protection station 100
transmits data to the integrator 115 which data has been
received and stored on the TAG or smart card 111 at the
cathodic protection station 100. The data transmitted from
the smart card 111 conveniently includes the location of the
particular cathodic protection station 100 being
interrogated such that it may be compared with the location
of the aircraft 114 by way of a GPS device 117 located in aircraf 114. Likewise , the transmission of data from the
cathodic protection station will be tested for integrity
during initial data transmission to ensure that all transmitting and receiving components on the station 100 are
operating properly. Then the charge characteristics
pertaining to pipeline 100 will then be obtained. Thus,
when the data is received by integrator 115, the location of
the particular cathodic protection station 100 and the charge characteristics associated with the pipeline 100 for
the location of each individual cathodic protection station 100 can be reviewed for determination of any remedial action
necessary. The received data may be stored for downloading
or reviewed in real time mode on the aircraft 114.
While an aircraft 114 has been described as being
useful to obtain the charge information from the cathodic
protection station 100, other vehicles may also be
conveniently used such as a ground based vehicle like a car
or a truck. It is important, however, that the vehicle
used, be it airborne or ground based, be brought relatively
closely to the cathodic protection station 100 in order to
allow the transceiver 112 on the station 100 to transmit the
stored data to the vehicle using a minimum amount of power from the batteries used. This will allow the life of the
batteries to be extended in order to avoid the use of local
based power supplied which may not be available in any event.
Many other modifications will readily occur to
those skilled in the art to which the invention relates and
the specific embodiments described should be taken as s illustrative of the invention only and not as limiting its scope as defined in accordance with the accompanying claims.