Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02391846 2002-06-27
Patent Applica3:ion
ROTATING PIG LAUNCHER
FIELD OF THE INVENTION
This invention relates to an apparatus for manual or automatic launching of
pigs into a
pipeline.
BACKGROUND OF THE INVENTION
The movement of petroleum products through pipelines is complicated by the
fact that
substances deposit on the walls or bottom of the pipe. In gas pipelines, water
and
hydrocarbons such as paraffin condense to the liquid phase, and the condensate
collects at
points where the pipeline is low relative to neighboring sections of pipeline.
The production
of condensate is a problem that is particularly acute in colder environments:
By forming
obstructions in the pipe, condensates, deposits and sediment reduce the
efficiency of a
pipeline by causing increases in pressure and a reduction in flow.
Pipelines are therefore regularly cleaned of deposits, condensates and other
debris that may
be present by use of a cleaning device commonly known as a "pig". Pigs are
passed through
the pipeline along with the flowing gas, which provides the pressure for
forward momentum
of the pig. The pig pushes ahead of it any foreign material that would
obstruct the flow
through the pipeline. The pig and the collected material is removed from the
pipeline at
various intervals.
Pipeline pigs can also be used for product separation, measuring volumes and
velocities, to
actuate signals and controls, for meter calibration and for testing of
pipelines. An ideal
pigging system, whether used for cleaning or otherwise; will get pigs into and
out of the
pipeline without flow interruption.
Various types of pigs have been described; such as spheres and cylinders, line
scrapers,
bullets, and cup pigs. As well, various devices for launching pigs into
pipelines have been
disclosed in a number of US Patents, including US Patent Nos. 4;073,303 to L.
E. Foley;
4,401,133 to R. J. Lankston; 4,435,872 to V. Leikam; 4,709,719 to J. Littleton
and G.W.
CA 02391846 2002-06-27
Davis; 5,139,576 to G. W. Davis; 5,873,139 to G. Goth; 6;022,421 to W: R. Bath
and C. R.
Yemington, and 6,079,074 to J.R. Ellett.
Many of these pig launching apparatuses use a storage mechanism that stacks
pigs one on top
of the other which causes unsafe heighf problems. See for example, US Patent
Nos.
4,709,719, 6,079,074 and 6,022,421. When pigs are stacked in this manner,
there is also the
possibility that two or more pigs would be launched into the pipeline at the
same time: If the
storage mechanism stores pigs horizontally, then the launching mechanism is
often more
complex as gravity alone will not suffice for launching the pigs. See for
example US Patent
Nos. 5,873,139. In yet other designs, the pig launching apparatus is designed
in such a way
that it only works with a particular style of pig; which limits the
adaptability of the apparatus
to new situations. See for example US Patent IVos. 4,401,133; 4,435,872;
4,709;719.
Therefore there is a need in the industxy for a pig launching apparatus that
is vertically
compact, simple to operate and which can accommodate various kinds of pigs.
SUMMARY OF TI3E INVENTION
IS It is thus the aim of this invention to provide an apparatus for launching
pigs that is vertically
compact, simple to operate; automatic, launches pigs by gravity, holds a
plurality of pigs and
which can accommodate various kinds of pigs:
There is therefore provided an apparatus for launching pigs into a pipeline
comprising a
housing, a supply magazine arranged in the housing with at least two pig-
holding chambers,
said pig-holding chambers each having an open bottom end, a closeable inlet
port through the
housing and providing access to the supply magazine, a launching chute
connectable to the
pipeline and positioned beneath, as determined by gravity, the supply
magazine, a drive
operatively connected to the supply magazine, said drive causing the supply
magazine to
rotate about a substantially vertical axis and position the holding chambers
each in turn
generally above the launching chute.
It is thus a feature of this invention to provide an apparatus that uses
gravity to introduce a
pig into a pipeline. This invention avoids the complexity of using pushing
devices, valves or
levers to position a pig onto launch a pig into a pipeline. Further, this
invention enables the
release of pigs in a controlled manner with 1i tle risk of inadvertently
releasing more than one
at a time.
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In a preferred embodiment of this invention, the supply magazine is a
generally circular disk
with a plurality of holding chambers spaced in an organized way about the disk
so that the
holding chambers can each in turn be positioned over the pig launching chute
such that any
pigs contained therein can drop by gravity into the chute. Thus the supply
magazine
functions both in pig storage and pig delivery to the pipeline: In this
embodiment many pigs
can be loaded into the supply magazine at once; which provides a savings in
manpower time
as only infrequent visits to the pig launcher are necessary. Further, because
the disk is
oriented on a generally horizontal plane the apparatus is vertically compact
which avoids the
height problems that are encountered with vertical storage mechanisms.
In another embodiment of this invention, two supply magazines are used to
increase pig
storage capacity. In this embodiment an upper supply magazine is positioned
above a lower
supply magazine, such that pigs from the holding chambers in the upper supply
magazine
automatically drop into or through the holding chambers of the lower supply
magazine upon
rotation of the upper supply magazine. The pigs in the lower supply magazine
successively
drop into thepipeline upon rotation of the lower supply magazine.
The supply magazine can be any desired shape that will permit carnage of pigs
and
positioning of the pigs individually over the chute by rotation of the
magazine.. In particular,
the supply magazine can be generally circular, square, rectangular or oblong
members
journalled to rotate about a generally vertical axis.
Preferably, the launcher includes a closable valve so that when the pig
launcher is connected
into a pipeline, the valve can be closed to isolate the interior of the
housing from the pipeline.
The valve can be located in or below the launching chute. Preferably, the
housing also has a
blow-down valve that is used to depre~surize the housing once the isolation
valve is closed
and before the housing is opened. In one embodiment, access to the supply
magazine for the
loading of pigs is gained by opening a quick closure on the inlet port.
Preferably, the holding chambers are formed to accommodate many of the kinds
of pigs used
in pipeline operations. The apparatus includes a floor under the supply
magazine on which
the pigs rest when in their holding chambers: The floor is open to the
launching chute and
prevents the pigs from dropping out of their holding chambers until they are
positioned over
the launching chute. Thus, the pigs are maintained in their holding chambers
until they are
pushed over the launching chute by rotation of the supply magazine. This
arrangement,
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4
which is not dependent on the length, shape, weight or composition of the pigs
being used;
can accommodate various kinds of pigs without modification. Further the
apparatus can be
modified to accommodate changes in the dimensions of the holding chambers that
might be
required to accommodate any pigs that are not or would not be able to be
launched by the
preferred embodiment describes herein.
The supply magazine can be rotated by many different means, including
manually,
electrically, pneumatically or by hydraulics. In a preferred embodiment a
drive mechanism
that is pneumatically operated is used, .which allows the apparatus to be used
in a remote
location with only a small power source.
I0 The drive mechanism can be actuated either manually or automatically. A
preferred
embodiment of this invention provides a :drive mechanism that is actuated
remotely. This
allows the launching of a pig into the pipeline as needed but precludes the
necessity of travel
to the site in order to do so. In yet another embodiment the drive mechanism
is actuated on a
timer to deliver a pig to the pipeline on a regular basis.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure I is a front elevation of a pipeline pig launching apparatus according
to the present
invention with the housing partially cut away to show a supply magazine, in
section along
line I - I of Figure 2. The apparatus is shown mounted on a valve assembly;
shown in
section, and a pipeline.
Figure 2 is a top plan view of the pipeline pig-launching apparatus of Figure
1.
Figure 3 is a cross sectional side view of a supply magazine useful in the
present invention.
The section is taken along line III - IIi of Figure 4:b.
Figure 4a is atop plan View the center support plate of the supply magazine of
Figure 3.
Figure 4b is a sectional view along line IV-IV of Figure 3.
Figure 5 is a top plan view of a rotation mechanism useful in the present
invention.
Figure 6 is a side elevation view of the rotation mechanism of Figure 5.
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Figure 7A is a front elevation view of another pipeline pig launching
apparatus according to
the present invention partially cut away to show a supply magazine, in
section.
Figure 7B is a schematic top plan view of the apparatus of Figure 7A showing
the positions
of the pig: launching chute, the inlet part and the access opening between the
upper and lower
5 magazines.
DETAILED DESCRIPTION Oh' PI2lrr)vRRED EMBODIMENTS
Figures 1 and 2 show a pig launching apparatus IO of this invention including
a housing I2, a
pressure release valve 14, a pig inlet 15 with a quick loading closure 16; a
supply magazine
18 including a plurality of holding chafinbers 20, each capable of
accommodating a pig 21,
and a rotation shaft 22, a rotation mechanism 24 for rotating the rotation
shaft of the
magazine and a pig launching chute 2b. Apparatus 1O is in communication with a
pipeline 28
through pig launching chute 26.
Housing 12 can be any shape that will accommodate supply magazine 18 and allow
supply
magazine 18 to rotate about a generally vertical axis within housing 12. The
housing is
preferably constructed of carbon steel, but can be made with any suitable
material that will
enable housing I2 to withstand the fluid pressures associated with an
operating pipeline,
since when the pig launching apparatus is in operation, the pressure in
internal chamber 30,
within housing I2 is equal to the pressure in pipeline 28.
To permit isolation of internal chamber 30 of housing 12 from pipeline 28; as
will be
necessary when opening the housing; a valve 32, such as a ball valve; is
provided between
pig launching chute 26 and the pipeline. The valve can be a part of the
existing pipeline, can
be installed with the apparatus of the present invention, or can be formed
integral thereto. A
pressure release valve 14 is also provided to equalize, as 'by controlled
release, the pressure in
the internal chamber with external pressure: once valve 32 is closed.
Pigs are loaded to the supply magazine through pig inlet 15: The pig inlet is
positioned
above, as determined by gravity, supply magazine I8 and the supply magazine is
rotatabIe
such that the holding chambers can each, in turn; be aligned with the pig
inlet and a pig
dropped therein. Thus, the pigs can be dropped-through the pig inlet and
loaded by gravity
into the holding chambers. The pig inlet can be in other orientations,
provided that it allows
for loading of the pigs into the magazine. Pig launching chute 26, shown in
phantom in
CA 02391846 2002-06-27
Figure 2; is offset from pig inlet 15 such that once a pig is placed into a
particular holding
chamber of supply magazine 18, the pig can only be released into the pipeline
by rotating
magazine 18 until that holding chamber is positioned over chute 26.
A floor SO is positioned directly below supply magazine 18 and prevents, by
obstruction, the
loaded pigs from dropping out of the holding chambers 20. When stored in the
magazine, the
pigs rest on the floor and extend up into their holding chambers. Upon
rotation of the
magazine, the pigs stored therein are pushed over he surface of floor S0.
Floor 50 includes
an opening 54 positioned above pig launching chute 26, said opening 54 being
sufficiently
large and correctly positioned to enable a pig to drop from an aligned one of
the holding
chambers into pig launching chute 26 when the rotation mechanism 24 positions
one of the
holding chambers above pig launching chute 2G. The lower ends of the holding
chambers
extend down to a point just above floor 50. The gap therebetween, is selected
to be
insufficient to allow the pig to jam therein.
On the bottom of housing 12 is drain valve 36; which can be opened to release
any fluid that
I5 may be trapped in housing 12. On either side of housing I2 are support tabs
37 which are
used to hold pig launching apparatus 10 in place at the site where it is
installed.
Figs: 3 and 4 show a preferred embodiment of supply magazine 18, which
includes an upper
support plate 38, a lower support plate 40, a center support plate 42 and
seven holding
chambers 20 equally spaced about a centrally located rotation shaft 22.
Holding chambers 20 are formed as tubes extending between at least the upper
support plate
and the lower support plate. A generally cylindrical tube is particularly
useful as it will
accommodate various kinds of pigs. In particular, the diameter of a pig which
is useful in a
particular pipeline is generally fixed based on' the diameter of the pipeline.
Thus, the
diameter of the holding chambers will be readily selectable depending on the
pipeline on
which the apparatus is to be used. In particular, a holding chamber should
have a diameter
slightly larger than the-pig to be launched therefrom:: This permits the pig
to sit loosely in the
chamber, without engaging therein but prevents a longer pig from tipping over
in the
chamber and becoming jammed therein or in the launching chute.
While the diameter of a pig may be generally fixed for any pipeline, the
length and shape of
the pig may vary and the cylindrical tube form of the present holding chamber
can
accommodate various lengths and shapes of pigs without changing the
functioning of the
CA 02391846 2002-06-27
apparatus. It will be appreciated, however, that the dimensions and number of
holding
chambers 20, and the dimensions of supply magazine L8 can be modified to
conform to the
size or type of pig that is to be used in any particular pipeline.
Support plates 38, 40: and 42 are used to- position and secure holding
chambers 20 in a
generally vertical position: Holding chambers 20 are atEached to upper, center
and lower
support plates 38, 40 and 42, as by welding. Rotation shaft 22 is rigidly
connected, as by
welding, to support plates 38, 40 and 42 and includes a guide collar 46 at its
lower end.
Support plates 38, 40 and 42, holding chambers 20 and shaft 22 are preferably
constructed of
stainless steel. The magazine is preferably stress -relieved at least once
during manufacture.
It will be appreciated hat there may be other designs of support plates; which
perForm the
functions of spacing holding chambers 20 and maintaining holding chambers 20
in a
substantially vertical position: These ~ilternate designs are intended to be
included herein.
However, this illustrated arrangement lias been found to substantially
eliminate twisting of
the structure during manufacture, for example during the stress relieving
process:
Supply magazine I8 can be constructed in other ways to achieve the same result
of
positioning substantially vertical holding chambers 20 about a central
rotation point. For
instance, rather than using support plates 38, 40 and 42 to hold and position
holding
chambers 20, supply magazine 18 can be constructed from a solid and generally
circular disk,
through which vertical through holes are drilled for holding chambers, the
through holes
being spaced in a way that will permit regulated pig launching through the pig
launching
chute.
For simplicity of operation, preferably the holding chambers are substantially
equally spaced
apart and spaced equally from the axis of rotation. As such, the rotation
mechanism need
only rotate the magazine a known degree for each launch and the launching
chute can be
positioned directly below the holding chambers so that the pigs drop directly
into the chute.
However, it is to be understood that other arrangements of holding chambers
can be
accommodated by adjusting the rotation mechanism or funneling the opening to
the chute.
In addition, in order to function in 'this invention, supply magazine 18 need
not be
substantially circular and holding chambers 20 and/or the axis of rotation
need not be close to
vertical. For example, a supply magazine that is square; rectangular, notched
or oval will also
function within the scope of this invention, provided that supply magazine can
be rotated to
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successively and controllably drop pigs into the pig launching chute by
gravity. In addition,
holding chambers 2U and the axis of rotation need only be vertically oriented
enough t4
permit pigs contained therein to drop with the force of gravity, into
pig,launching chute 26,
when a holding chamber is positioned above the chute; or generally above it.
These alternate
designs are intended to be included in the scope of this invention.
Referring again to Figure I, rotation shaft 22 extends through the housing and
up to rotation
mechanism. Rotation-shaft 22 at its upper end is attached to rotation
mechanism 24 via a
rotator hub 25. Therefore, when rotator hub 25 is turned by rotation mechanism
24, shaft 22
and supply magazine I8 rotate with it:
Magazine I8 is supported on a support 44 extending up from the housing. In
particular,
guide collar 46 of the shaft nests over the tip of support 44: Shaft 22 is
journalled between
support 44 and a collar 58, which is aligned ,with an opening through housing.
Collar 58 is
welded to housing 12 and is hollow; thus enabling rotation of shaft 22
therein: Collar 58
extends down to an end disposed just above upper support plate 38, and also
functions to hold
supply magazine 18 against movement upwardly in the housing. Tn particular,
when
operating the apparatus, the pressure from pipeline 28; especially when
opening valve 32,
will sometimes tend to force supply magazine 1$ upwards: However, collar 58
will maintain
the magazine in position by abutment thereagainst.
The upper end of collar 58 extends out through housing l2 arid is welded to a
flange 60. A
packing gland 62 is mounted above Mange 60 and a seal 63 is disposed
therebetween.
Packing material in packing gland 62 is compressed therein by packing gland
follower 64 to
form a tight seal about shaft 22 so that the pressure in housing 12 is
maintained. Bolts 66
secure packing gland GO and packing gland-follower 64 to flange 60 and thereby
to the top of
housing l2. Bolts 66 can be tightened to adjust the seal provided by packing
gland 62.
Referring now to Figures 2; 5 and 6, a rotation mechanism 24 useful in the
present invention
is shown. Rotation mechanism 24 provides a means for rotating the magazine in
regular
intervals corresponding with the position of each holding chamber relative to
the pig
launching chute. In the illustrated embodiment, the rotation of magazine 18 is
driven
pneumatically and the rotation device includes a pneumatic cylinder 72 secured
to a
stationary support, i:e. a cylinder support 68 secured to pig inlet 15. The
use of a pneumatic
drive is preferred for use in the present'apparatus, as it can be operated for
long periods with
CA 02391846 2002-06-27
a small power source such as an automobile battery. Thus, the present pig
launching
apparatus can be used in remote locations even away from power lines.:
Pneumatic cylinder ?2 is attached by a hinge 70 to pneumatic cylinder support
68 and
cylinder rod,73 is connected to an outer linkage plate 74 at pivot 76. Outer
linkage plate 74 is
in turn connected to an inner linkage plate 78 at pivot 80. Inner linkage
plate 78 is connected
to shaft 22 but is free to rotate thereabout as limited by outer linkage plate
74 and cylinder 72.
As moved by extension and retraction of cylinder rod 73, the assembly of
cylinder 72, outer
linkage plate 74 and inner linkage plate 78 is moveable in parallel planes in
an arc about shaft
22.
Outer linkage plate 74 includes a prolrusioa 86 that is engagable info an
aligned one of the
notches 88 on a notched rotator plate 82. Inner linkage plate 78 is shown
partly in phantom
in Figure 5 as it is positioned beneath both outer linkage plate 74 and
notched rotator plate
82. Rotator hub 25 is rigidly secured, as by welding, to notched rotator plate
82 and rigidly
secured to rotation shaft 22 preferably by a keyway or set screws. Thus, any
movement of
plate 82 or rotator hub 25 is directly translated to shaft 22. A nut 98
threads onto the shaft
below inner linkage plate 78 to secure all linkage components together.
However, spacing
washers 100 eliminate friction between linkage components and isolates
movement of inner
linkage plate 78 from rotator plate 82 and shaft 22, except through outer
linkage plate 74.
The notches 88 on notched rotator plate 82 correspond with the positions of
the holding
chambers in the magazine. In particular, preferably; the notches are arranged
similarly to,
and of a number equal to the number of holding chambers in the magazine such
that when
protrusion 86 is engaged in a particular notch, one corresponding holding
chamber will be
positioned over pig launching chute 2G:
In Figure 5, the rotation mechanism is shown in a disengaged position wherein
rod 73 is fully
retracted and protrusion 86 is not engaged-in any notch. In this position, the
shaft is not
driven by the mechanism and the shaft can be rotated manually. This position
is the normal
operating position for the mechanism between advancing the magazine and is the
position
necessary fox loading pigs to the magazine. In particular, during loading of
pigs, it is
desirable that the shaft be free of the mechanism so that magazine can be
rotated manually to
align the holding chambers with pig inlet. Rotator hub 25 is preferably formed
as a hex to
facilitate manual rotation of the shaft, as by engagement with a wrench.
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During use, the notched rotator plate 82 is moved to rotate by protrusion 86
engaging in a
notch and the cylinder rod being extended to push he outer linkage plate 74
forward and, as
limited by inner linkage plate 78, to rotate the shaft. In particular, in one
advancement cycle,
rod 73 is first extended so that protrusion 86 is moved from the position
shown in Figure 5 to
5 a position wherein it is engaged in a notch 88: In this position, a holding
chamber will be
disposed over pig launching chute 26. That holding chamber will be empty
having already
dropped any pig; once contained therein; into the,pipeline: To advance the
magazine so that
the next holding chamber is located over the pig launching chute and to
release another pig
into the pipeline; rod '73 is further driven to extend which causes outer
linkage plate 74 to
10 pivot around hinge 76 and pivot 80 and move in a direction as indicated by
arrow 93. Since
the connection between outer linkage plate 74 and inner linkage plate 78
restricts the outer
linkage plate to move in an arc about shaft 22, the protrusion remains in
notch 88 and drives
rotator plate 82 to rotate, also in the direction indicated by arrow 93. Once
the rod reaches
the outer extent of its travel, the cylinder then begins to retxact rod 73.
The outer extent of
rod travel can be set by adjustment of the rod itself or by abutment of inner
linkage plate 78;
for example at free end 96, against a stationary object such as inlet 15. The
frictional
resistance to pivotal motion about pivot 80 is selected to be less than that
of inner linkage
plate 78 about shaft 22 such that when the rod is retracted, the outer linkage
plate will first
pivot about pivot 80 and pull protrusion 86 out of the notch in which it was
located
substantially without rotating plate 82: The rod will continue to retract to a
position shown in
Figure 5, moving inner linkage plate 78 and outer linkage plate 74 in a
direction indicated by
arrow 94. The mechanism will remain in the position as shown in Figure 5 until
it receives a
signal to repeat the cycle to advance the magazine, at which point the
protrusion will be
advanced and engage in the next adjacent notch; in the drawing this notch is
indicated as 92.
2S As will be appreciated, the rod, and corresponding configurations of plates
74, 78 and 82
must be selected to provide proper advancement of the magazine and alignment
of the
protrusion with the next adjacent notch on the return cycle.
Although shaft 22 can be rotated manually, it is generally resistant to
rotation. Therefore,
although protrusion 86 is not normally engaged in a notch, the magazine tends
not to rotate
on its own. If it should occur that the rotator plate has been rotated between
cycles and the
protrusion does not directly align with a notch when it is advanced; the
protrusion will tend to
be driven along the outer edge of rotator plate 82 until it drops into a notch
and will then
begin to turn the shaft.
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11
Cylinder 72 can be actuated to move through its cycle of extension and
retraction by any
suitable means such as a timing device, remote control or manual actuation of
a switch on the
apparatus. The cylinder is attached to a fluid pressure device such as a
nitrogen tank, a
compressed air tank and/or a pump.
In the illustrated embodiment, rotation mechanism 24 drives supply magazine 18
to rotate in
a clockwise direction However; by simple modification rotation in a
counterclockwise
direction can be achieved.
To reload supply magazine 18 with pigs, ball valve 32 is closed to isolate
internal chamber 30
from pipeline 28 and pressure in internal chamber 30 is released by opening
pressure release
valve 14 before opening closure 1G. Since protrusion 8~ is normally disengaged
from notch
88, supply magazine 18 can be manually rotated within housing 12, in either
orientation.
Manual rotation can be effected by turning shaft 22, magazine 18, or rotator
hub 25.
The procedure to reload the magazine with pigs vvih be dependent on the
relative positions of
pig inlet 15 and pig launching chute 26. In the illustrated embodiment, the
pig inlet is
positioned to Load into the holding chamber directly clockwise from the one
located over the
pig launching chute. Thus, to reload the apparatus of the illustrated
embodiment, it is first
rotated counterclockwise to count the number of empty holding chambers
therein. The
magazine may contain some pigs or be entirely empty. Counterclockwise rotation
is
discontinued when an occupied holding chamber 20 is located or when it is
determined that
the magazine is completely empty. Then supply magazine 18 is rotated clockwise
and,
beginning with the first empty holding chamber, one pig is dropped through pig
inlet 15 into
the empty holding chamber aligned therebelow. Supply magazine 18 is then
advanced
clockwise so that thenext empty holding chamber 20 aligns with inlet port 15
and one pig is
dropped through the pig inlet into that holding chamber: This process is
repeated until a
selected number of the empty holding chambers 20 have been charged with one
pig each.
During reloading the holding chamber 20 that; after loading is completed, is
positioned
directly above pig launching chute 26 can be left empty. Alternately, if it is
desired to launch
a pig into the pipeline immediately after reloading, pigs can be loaded into
all empty holding
chambers 20, which will result in the pig from the holding chamber directly
over pig
launching chute 26 dropping into the chute and resting on top of valve 32. As
will be
appreciated, it will be necessary to know the total number of holding chambers
in the
magazine and the number of empty holding chambers prior to reloading in order
to properly
CA 02391846 2002-06-27
12
reload the device, since if a loaded holding chamber is rotated over the chute
prior to being
rotated under the pig inlet, it would appear empty although the pig loaded
thereto had just
dropped into the launching chute. In the; embodiment shown in FIG 3B; a
maximum of seven
pigs could be loaded into empty supply magazine 18:
In the preferred embodiment, the pig islet is positioned to load into the
holding chamber
directly beside the one located over the pig launching chute. Thus, it is easy
to load the
magazine leaving just the holding eharnber over launching chute 2b empty. In
addition, when
looking into the pig inlet, pig launching chute 26 can be seen on the other
side of the supply
magazine, and it is possible to determine whether or not there is a pig
located in the chute.
After loading the magazine, closure 16 is closed and seiiled and valve 32 is
opened: When
the ball valve is opened after the loading operation; any pig in pig launching
chute 26 will
enter the pipeline immediately.
Although this invention will enable pigs to be launched into pipelines using
gravity alone, it
may be desirable to use pressure in addition to gravity, to launch a pig. This
may be useful
where a pig is stuck in the holding chamber or in he launching chute.
Therefore, in an
alternative embodiment of pig launching apparatus 10, additional external
pressure is
introduced into housing 12 via a pressurization nozzle (not. shown) contained
therein: This
additional pressure is applied to the top of the pig and forces it into the
launching chute:
Figures 7A and 7B show an alternative embodiment of this invention that
increases the
storage capacity of pig launching apparatus 10a. In this embodiment, a second
supply
magazine 18b is positioned above the; first supply magazine and a second floor
SOb is
positioned between supply magazines 18 and 18b to support the pigs in supply
magazine 18b.
Supply magazine 18 has holding chambers 20 and supply magazine 18b has holding
chambers ZOb. To simplify operation and manufacture of the pig Iaunahing
apparatus; the
holding chambers in each magazine are similar in number and position.
In this embodiment, rotation shaft 22 xotates both magazines 1$ and 18b
simultaneously.
Shaft 22 has a rotation mechanism 24 in driving communication therewith.
To permit loading and unloading of the two magazines, an opening 98 is
positioned in floor
SOb that is one holding chamber position clockwise from pig launching chute 26
and inlet 15
is aligned with the holding chamber that would be two positions clockwise from
the holding
CA 02391846 2002-06-27
chamber aligned above pig launching chute 2b: With this configuration, both
supply
magazines can be loaded with pigs by turning he shaft, and attached magazines,
clockwise,
as indicated by the arrow in Figure 7B. :Continued clockwise turning of shaft
will unload the
pigs from magazine 18 into launching chute 26 one-by-one. As the supply
of,pigs in bottom
magazine 18 is launched; the upper supply of pigs from magazine 18b will drop
one-by-one
to refill the lower magazine.
The apparatus of Figure 7A with two magazines; each including seven holding
chambers,
will hold 12 or 13 pigs, depending on whether or not one is dropped into the
pig launching
chute during the loading process. The upper holding chamber above opening 98
should
remain empty during the loading Process, to avoid jamming of pigs between the
magazines
and the opening.
Of course, the apparatus could be operated in a counterclockwise direction by
aligning the
inlet port and the floor opening on theotber side of the pig launching chute.
It will be apparent that many other changes may be made to the illustrative
embodiments,
while falling within the scope of the invention and it is intended that all
such changes be
covered by the claims appended hereto:
