Note: Descriptions are shown in the official language in which they were submitted.
CA 02468652 2004-05-28
FLUID SAMPLING DEVICE
FIELD OF THE INVENTION
The present invention relates to a sampling device for sampling fluid
from a fluid line having fluid therein flowing under pressure, and more
particularly
relates to a device for sampling oil from a pipeline flow.
BACKGROUND
In many instances it is desirable to sample a fluid flowing in a pipe to
test various characteristics of the fluid. In the oil industry, it is
particularly desirable to
obtain samples from crude oil flowing in pipes for measuring the water content
thereof. Sampling in this instance is commonly done in a satellite building at
an oil
field where a plurality of wells flow into a common header at the building. A
pressure
vessel is typically provided through which a selected one of the wells may be
diverted
when it is desirable to meter the flow therethrough. Gas is typically removed
at the
pressure vessel and diverted downstream back into the pipe line. A flow meter
downstream from the pressure vessel measures the flow of crude oil from the
selected one of the wells through the pressure vessel.
A known type of sampling involves a rotary valve in the form of co-
operating apertures in plates which rotate past one another to open and close
the
valve. The fluid sample is dispensed to atmosphere and gases are permitted to
escape into the surrounding environment. Rotation of the valve is dependent
upon
rotation of the flow meter to which it is connected resulting in inconsistent
sample
volumes dependent upon flow conditions.
SUMMARY
According to one aspect of the present invention there is provided a
sampling device for sampling fluid from a fluid line having fluid therein
flowing under
pressure, the device comprising:
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a container;
a sampling line for communication between the fluid line and the
container;
a sampling valve mechanism in series with the sampling line, the
sampling valve mechanism being arranged to release a fluid sample of
prescribed
volume through the sampling line with each operating cycle of the sampling
valve
mechanism; and
a control mechanism for operating the sampling valve mechanism
through a plurality of operating cycles at timed intervals throughout a
prescribed
sampling duration to release the fluid samples of prescribed volume into the
container.
By providing a valve mechanism which consistently produces a fluid
sample of prescribed volume with each cycle and a control mechanism for
cycling the
mechanism at evenly spaced intervals, consistent sample sizes over a
prescribed
sample duration can be attained for producing a more accurate overall sample
of the
fluid flowing through the pipe line. Furthermore by providing the valve in
series with
the sampling line, the fluid being sampled remains contained in the sampling
line for
capturing gases dispensed and properly disposing of them once collected. In a
preferred embodiment, the valve mechanism comprises a simple mechanism of two
valves which extracts a predictably sized small sample which remains fixed in
volume
through out the duration of the sampling despite fluid pressures or flows in
the pipe
line, thus permitting many samples to be extracted into a small portable
container
which can then be taken back to a testing area.
The device may be provided in combination with an oil pipe line for
sampling oil from the pipe line.
The sampling line may communicate with the fluid line through an inlet
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tube having a bevelled free end facing into the direction of flow in the fluid
line.
There may be provided a responsive shut-down valve in series with the
sampling line between the fluid line and the sampling valve mechanism, the
responsive shut-down valve being responsive to fluid in the container reaching
a
prescribed fluid level for shutting off flow through the sampling line.
The container may be supported on a scale platform which closes the
responsive shut-down valve when a prescribed weight of fluid corresponding to
the
prescribed level is reached.
The prescribed weight of the scale is preferably adjustable.
A flexible line may couple the sampling line to the container supported
on the scale.
The responsive shut-down valve preferably requires manually resetting.
There may be provided a vent line coupled to the container.
The sampling valve mechanism preferably comprises a pair of sampling
valves in series with the sampling line in which the control mechanism is
configured to
permit only one of the sampling valves to be opened at any given time.
Preferably at least one of the sampling valves is opened at evenly
spaced timed intervals.
Volume of the sampling line between the sampling valves is preferably
approximately between 5 and 10 millilitres so as to be approximately less than
1 % of
the volume of the container when the container volume is 1 litre.
The sampling valves are preferably biased towards the closed position.
The control mechanism may include a cam member having at least one
lobe thereon which deflects a cam follower on a lever arm operating one of the
sampling valves.
Preferably both sampling valves include lever arms with cam followers
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thereon which operate the valves in which both cam followers ride along the
same
cam member to ensure that only one of the valves is opened at any given time.
There may be provided a manually operated shut-down valve coupled in
series with the sampling line between the fluid line and the sampling
mechanism.
There may be provided a cleanout line coupled to the sampling line
between the fluid line and the sampling mechanism, the cleanout line including
a shut-
off valve in series therewith.
BRIEF DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, which illustrate an exemplary
embodiment of the present invention:
Figure 1 is a front elevational view of the sampling device.
Figure 2 is a side elevational view of the sampling.
Figure 3 is a partly sectional top plan view of the inlet tube.
Figure 4 is a schematic view of the operation of the sampling device.
DETAILED DESCRIPTION
Referring to the accompanying drawings, there is illustrated a fluid
sampling device generally indicated by reference numeral 10. The device 10 is
particularly suited for use with an oil pipe line 12 containing a flow of
crude oil under
pressure therein.
The device 10 includes an inlet tube 14 which extends through the side
wall 16 of the pipe line for communication with an interior of the pipe line.
A free end
of the tube 14 is sloped at a 45° bevel which is oriented to face into
the flow direction
20 to ease the flow of fluid into the inlet tube 14.
The inlet tube is coupled in series to a manual shut-off valve 22 which
further connects the inlet tube 14 in series with a sampling line 24. The
manual shut-
off valve 22 includes a suitable manual lever for operating an interior ball
valve to
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open and close the valve as desired.
The sampling line 24 extends between the inlet tube 14 in
communication with the pipe line 12 and a container 26 which receives the
fluid being
sampled from the pipe line. The sampling line 24 couples to the container 26
by a
flexible line 28 coupled therebetween. Connection of the flexible line 28 to
the
container is sealed to ensure that all fluid dispensed therethrough is
delivered into the
container. The flexible line connects to a threaded cap of the container so
that the
cap can be threadably removed from the container for replacing the container
as
desired. Both the sampling line 24 and the flexible line 28 are supported in a
horizontal orientation at a connection point with each other and a vertical
vent line 30
which extends vertically upward therefrom to a suitable vent external from the
building
or to a suitable collection of the gases in an environmentally friendly
manner.
A sampling valve mechanism 32 is provided in the form of two sampling
valves 34 coupled in series with the sampling line 24. Each of the valves 34
is biased
towards a closed position and includes an actuating lever 36 which opens the
valve
when the lever is deflected.
A responsive shut-off valve 38 is coupled in series with the sampling line
between the inlet tube 14 and the sampling mechanism 32 for shutting off the
flow into
the sampling device 10 when a prescribed fluid level is reached within the
container
26. The container is supported on a scale platform 40 which is pivoted along a
rear
side by a hinge 42 for pivotal movement up and down from a horizontal position
when
supporting the container thereon in use. A spring 44 biases the platform
upwardly
while weight of fluid in container acts against the spring to deflect the
platform
downwardly. When a prescribed weight of fluid within the container, indicative
of a
prescribed level being reached, the scale platform 40 is configured so as to
be
sufficiently deflected to engage the actuating lever 46 of the responsive shut-
off valve
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38 and thereby close the valve. The spring tension of the spring 44 is
adjustable by
means of the threaded bolts securing the opposing ends of the spring so that
the
prescribed weight or level of fluid being collected can be adjusted. Once the
shut-off
valve has been closed, manually resetting the valve is required by replacing
the
container and resetting the position of the scale platform 40 in a horizontal
orientation.
A cleanout line 48 is coupled to the sampling line 24 between the
responsive shut-off valve 38 and the settling mechanism 32 to provide an
alternate
route for the fluid to flow through when a cleanout valve 50 in series with
the cleanout
line 48 is opened. The cfeanout valve 50 is a manually operated ball valve
including a
suitable lever for opening and closing the valve. Samples may be directly
taken from
the sampling line manually by operating the cleanout valve 50.
A valve controller 52 comprises an electric motor having a rotary output
which can be selected to operate at one of various speeds. The motor is
battery
powered to readily permit its use in various environments.
A cam member 54 is supported on the rotary output of the valve
controller and includes two diametrically opposed lobes 56. A cam follower 58
is
provided on the actuating lever 36 of each of the sampling valves 34 for
engaging the
cam member 54 throughout its rotation. The cam member preferably includes
smooth
rounded camming faces on the lobes 56 which may be formed of TefIonT"" or
other
suitable self-lubricating materials. The cam followers 58 are also made of a
plastic
material which is smooth and rounded in profile for riding along the camming
faces of
the cam member to deflect the lever 36 and open the respective valve 34 each
time
one of the lobes is rotated therepast.
By rotating the cam member 54 the sampling valves 34 are alternately
opened. The cam followers 58 of the respective sampling valves are located
adjacent
one another, within 90 degrees measured circumferencially relative to the cam
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member axis, so that only one of the valves may be opened at any given time by
the
diametrically opposed lobes 56. When a first one of the sampling valves 34
nearest
the pipe line is first opened, a sampling portion 60 of the sampling line
between the
valves 34 is pressurized to the same pressure as the pipe line. The first
sampling
valve 34 then closes and the other sampling valve 34 downstream therefrom is
then
opened to release the fluid under pressure in the sampling portion 60 of the
line into
the container 26. A consistent sample volume is thus released with each cycle
of the
sampling valve mechanism 32 dependent upon the volume of the sampling portion
60
of the line. In the preferred embodiment, the sampling portion has a volume
which is
suitable to produce a sample of approximately 7 millilitres. The cam member 54
is
evenly rotated so that in addition to consistent sample volumes, the samples
are
taken at consistent timed intervals evenly spaced apart regardless of the flow
conditions of the meter of the pipe fine 12 to which the sampling device may
be
connected.
As described herein, the sampling device connects to a pipe or meter
containing a flowing oil/water emulsion. The inlet tube is comprised of '/4
inch
stainless steel tubing approximately 3 inches long. One end which is directed
into the
fluid stream is bevelled to 45 degrees. The other end is press fitted into a
1/8 inch to
'/4 inch swedge. The '/4 inch end of the swedge is connected to a '/4 inch
ball valve ('/4
turn) to permit and stop flow from the source to the sampling device. The
valve is
then fitted to an InvaIcoT"" Microvalve. This valve is bolted to the frame of
the
sampling device. The valve acts as a safety shut down and will close if the
fluid level
reaches a certain level. The valve must be manually reset open in order for a
sample
to be taken. From the safety valve, the fluid will then flow up '/4 inch line
to a stainless
steel T where it can be diverted to a clean out/sample '/4 inch ball valve
which is
normally closed. The flow also goes in the direction of the first of finro
InvaIcoT""
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Microvalves. These two valves are separated by a 3/8 inch holding tube which
has a
capacity of about 7 ml. The first valve is a operated by a spring loaded lever
which
maintains the valve in a normally closed position. The fluid will only pass by
this valve
when a cam rotates past the plastic ball on the end of the valve lever
assembly. The
lobes of the cam will rotate past this ball every 30min or 45min. The cam is
driven by
a battery operated (1.5V) drive system which can be set for different rotation
times (60
or 90 minutes). When the cam passes over the first valve it will open it
allowing the
fluid to flow into the pressure tube. The cam will then pass over the lever of
that valve
allowing the spring loaded lever to close the valve capturing the fluid in the
pressure
tube so that the pressure will be equal to sample inlet pressure. The cam will
then
rotate to the ball lever of the second valve, opening the microvalve and
releasing the
pressure of the pressure tube through the second valve and up into the flow
sample
line. The continuous cycle of releasing pressurized fluid into the sample line
will in
turn flow into the sample jug. This test will continue for a given time or
until the
sample reaches a certain level and trips the safety valve. The sample
jug/container is
held in place by a bracket mounted on a 6 inch T hinge which allows it to move
up
and down on the side of the safety valve. The fluid shut down level can be
adjusted
by the a spring and eye bolt. The gas in the jug is allowed to escape through
a vent
line connected to the top of the sample line by the way of a '/4 inch T
fitting. The fluid
will then flow from the fitting to the jug by the way of a flexible'/4 inch
fuel line allowing
the sample jug to move down in case of a high fluid level(weight). The sample
jug is a
standard 1 L fluid sample jug fitted with a screw top. The fuel line is fitted
into '/4 inch
hole in the center of the cap.
In use, the device is coupled to a pipe line exiting a pressure vessel at a
satellite building of an oil field at the flow meter thereof. All of the
components of the
device as described herein are supported within the building on by a suitable
housing
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as shown in the accompanying figures. Rotation speed of the cam member 54 is
selected on the valve controller 52 so that each rotation of the cam member
produces
two cycles of pressurizing the sampling portion 60 of the line and releasing
the
pressure as a fluid sample into the container when two lobes 56 are provided
thereon.
The response shut-off valve 38 ensures that fluid flow into the sampling
device is cut
off once a desired volume of the fluid has been collected. The container 26 in
the
preferred embodiment has a volume of approximately 1 litre and is coupled to
communicate with the vent line 30 to vent excess gases externally of the
building site
or through any other approved collection or disposal means.
In further embodiments the sampling valve mechanism 32 may
comprises a single high speed solenoid valve which is precisely controlled to
open for
specific durations to control the amount of fluid being sampled upon each
cycle.
While one embodiment of the present invention has been described in
the foregoing, it is to be understood that other embodiments are possible
within the
scope of the invention. The invention is to be considered limited solely by
the scope
of the appended Claims.
