Note: Descriptions are shown in the official language in which they were submitted.
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CLEANI~1~ TANK
This invention is in the field of tanks and like storage containers and in
particular
apparatuses and methods used in the cleaning of sediment from tanks such as
are used in
oil storage.
~CKGROUND
Storage tanks and similar containers are used in a number of industries as a
temporary
storage site for a wide variety of materials. One such example is storage
tanks used to
hold crude oil. In areas where access to a pipelinc is not available, storage
of crude oil
aRer extraction from the well is necessary until such time as the oil can be
removed to a
refinery, typically using a tanker truck.
A problem with the storage of crude oil extracted from underground formations
is that it
commonly contains suspended sediments such as sand. During the extraction
process,
these sediments remain in suspension however once the crude oil is in a
storage tank,
these sediments settle to the bottom of the tank, accumulating over time. If
allowed to
accumulate, these sediments will eventually cause blockage of outlet ports in
the tank
through which the oil is normally removed.
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Should these ports become block, it is usually necessary to completely drain
the tank,
disassemble it, and then clean out the sediments. This is an expensive and
time-
consuming process that creates the risk of environmental pollution during the
removal of
the crude oil trapped in the tank. In addition, a replacement tank must be
provided if
continued production from the wellhead is desired during the time the fouled
tank is
being serviced.
As a result, it is common practice in the field to attempt to clean sediments
out of tanks
on a regular basis, in order to keep sediment levels from interfering with the
removal of
oil from the tank. There are a variety of manual and mechanized prior art
methods of
cleaning sediments from oil storage tanks. Manual methods suffer from the
common
problem that they are tedious, time-consuming and that they expose the worker
to
potentially hazardous substances. Mechanized methods have bin developed that
avoid
workers entering tanks.
The typical method for cleaning oil field tank involves inserting a pressure
wand through
a port located in the tank wall just above the floor of the tank. Such ports
are provided on
the tank and have a valve closing the port that has exposed threads for
attachment of
various fittings as might be required. When cleaning is required a crew
arrives at the
tank and threads a cleaning assembly onto the valve. The cleaning assembly
typically
comprises a large vacuum tube threaded into the valve and attached to a vacuum
truck
that applies suction to the interior of the vacuum tube. A smaller pressure
tube or wand is
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slidingly sealed in the outer end of the vacuum tube, and a pressurized water
supply,
typically mounted on a separate pressure truck, is connected to the wand to
supply high-
pressure water to the wand. The valve is then opened and the wand is pushed
into the
tank. The high-pressure water stream dislodges the sediment and then the
resulting slurry
of water and sediment is aspirated into the vacuum truck through the annulus
between the
inner wall of the vacuum tube and the outer wall of the wand. The wand is
pushed
forward, dislodging the sediment as it goes, until it has reached the opposite
wall of the
tank. The wand may be moved, back and forth several Limes to remove as much
sediment
as possible.
The portion of the tank that is effectively cleaned comprises a relatively
narrow strip
emanating from the site of the port to the opposite wall of the tank. As a
result, a
significant portion of the bottom of the tank remains covered in sediment
necessitating
more frequent cleaning in order to prevent blockage of the ports by sediments.
A way in
which this type of limitation has been addressed is to fit a tank with
multiple entry ports.
This is a less than desirable solution as it increases the complexity of the
tanks and hence
the cost to manufacture. 1n addition it means that in order to fully clean the
tank bottom
of sediment, multiple operations are required, increasing the time and effort
needed to
properly clean the tank.
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Considerable prior art is directed to various means and methods for cleaning
tanks, for
example as disclosed by United States Patent plumbers 6,371,137 to Heath,
3,895,756 to
Jaeger, 5,460,331 to Krajicek et al., and 5,195,548 to Roger.
SUM1V1ARY OF THE INVENTION
It is an object of the present invention to provide an adapter apparatus and
method for use
in cleaning sediment from storage tanks that overcomes limitations in the
prior art.
The invention provides, in one embodiment, a cleaning adapter apparatus for
attachment
to a lower portion of a tank wall. The apparatus comprises a swivel support
device
adapted to be fixed to the tank wall over a wall aperture in the lower portion
of the tank
wall such that the swivel support device is sealed to the tank wall. A
swiveling body
defines a cleaning channel therethrough and is sealed in the swivel support
device such
that the swiveling body can move at least horizontally and such that an outer
end of the
cleaning channel is exposed on an outside of the tank, and an inner end of the
cleaning
channel is exposed on an inside of the tank when the swivel support device is
fixed to the
tank wall. A valve is connected to the outer end of the cleaning channel and
is adapted
for connection to a vacuum tube with an internal pressure wand such that the
pressure
wand can pass through the valve and cleaning channel into the tank, and the
wand then
connected to pressure truck for cleaning the tank.
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'fhe invention provides in a second embodiment a tank and cleaning apparatus
comprising a swiveling body defining a cleaning channel therethrough and
scaled in a
lower portion of a tank wall such that the swiveling body can move at least
horizontally
and such that an outer end of the cleaning channel is exposed on an outside of
the tank,
and an inner end of the cleaning channel is exposed on an inside of the tank.
A valve is
connected to the outer end of the cleaning channel and is connected by a
vacuum tube to
a vacuum source. A pressure wand is operatively connected io a pressurized
liquid
source and slidably sealed inside the vacuum tube such that the pressure wand
can slide
inside the vacuum tube and through the valve and the cleaning channel such
that a nozzle
end of the pressure wand is inside the tank.
The invention provides in a third embodiment method of cleaning sediment from
a tank
with a vacuum tube that includes a pressure wand slidably sealed inside the
vacuum tube.
The method comprises providing a swiveling body defining a cleaning channel
therethrough and sealed in a lower portion of a tank wall such that the
swiveling body can
move at least horizontally and such that an outer end of the cleaning channel
is exposed
on an outside of the tank, and an inner end of the cleaning channel is exposed
on an
inside of the tank, and providing a valve having a first port connected to the
outer end of
the cleaning channel; connecting the vacuum tube to a second port of the valve
and
opening the valve; pushing the pressure wand through the valve and the
cleaning channel
into the tank and pushing the pressure wand back and forth and substantially
horizontally
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fmm side to side while directing a flow of pressurized water through the
pressure wand
and drawing a sediment slurry out of the tank through the vacuum tube.
A high-pressure pressure wand is inserted through the swiveling body into the
tank in a
conventional manner. Horizontal movement of the swiveling body permits an
operator to
achieve improved coverage of the tank bottom during cleaning operations. The
dislodged
sediments can be sucked out of the tank in the space between the walls of the
vacuum tube
and the wand by a vacuum truck in a conventional manner.
1Q The adapter apparatus of the invention provides for removal of a greater
amount of the
sediments in a tank, without the need to empty, decommission or disassemble
the tank,
and via a single port of entry into the tank. The adapter apparatus is simple
and readily
adapted to existing oil ston~ge tanks. In construction of new tanks a
swiveling body and
swivel support device can be incorporated into a lower portion of the tank
wall
1S
DESCRIPTION OF THE DRAWINf'~
While the invention is claimed in the concluding portions hereof, prefetxed
embodiments
20 are provided in the accompanying detailed description which may be best
understood in
conjunction with the accompanying diagrams where like parts in each of the
several
diagrams are labeled with like numbers, and where:
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Fig. 1 is a schematic side view of an embodiment of the present invention as
installed in
the side of an oil storage tank;
Fig 2A is a schematic top view showing the cleaning pattern obtained with a
prior art
device the apparatus of the present invention; and
Fig 2B is a schematic top view showing the cleaning pattern obtained with the
apparatus
of the present invention.
Fig. 3 is a perspective exploded more detailed view of the embodiment of Fig.
1 showing
stop plates added to the outer retaining flange;
Fig. 4 is a side view of the adapter apparatus of Fig. 3.
DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS
Fig.l schematically illustrates a tank cleaning system comprising an
embodiment of the
cleaning adapter apparatus 1 of the invention mounted on a lower portion of
the wall 2 of
a tank, such as an oil storage tank. The cleaning adapter apparatus 1
comprises a swivel
support device adapted to be Fuced to the tank wall ovcr a wall aperture in
the tower
portion of the tank wall such that the swivel support device is sealed to the
tank wall. In
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the illustrated embodiment the swivel support device is provided by inner and
outer
retaining flanges 3, 5.
A swiveling body defines a cleaning channel therethrough and is sealed in the
swivel
support device such that the swiveling body may move horizontally and such
that an
outer end of the cleaning channel is exposed on an outside of the tank, and an
inner end
of the cleaning channel is exposed. In the illustrated embodiment the
swiveling body is
provided by a spherical gimbal 6.
In the illustrated embodiment the inner retaining flange 3, is attached over
an aperture in
the wall 2 of the tank. The inner retaining flange 3 cwt be attached by
permanent
methods such as welding as illustrated, or by non-permanent methods using
conventional
fasteners such as nut and bolt combinations and the like. The outer retaining
flange 5 is
attached to the inner retaining flange 5 by bolts 4 threaded into threaded
holes in the inner
retaining flange 3.
The spherical gimbal 6 is sealed between the retaining flanges 3, 5. The inner
surfaces of
the inner and outer retaining flanges 3, 5 are formed such that when affixed
to each other
they form a cavity operative to receive and hold the gimbal 6 in place.
Conveniently, the
dimensions of the cavity formed by the flanges 3, 5 are such that when the
gimbal 6 is
placed between the inner and outer retaining flanges 3, 5, fastening of the
flanges clamps
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the gimbal 6 in place with sufficient force to seal the gimbal 6 while still
allowing it to
move relatively freely.
In the illustrated embodiment, fastening of the two flanges is by bolts 4 as
illustrated in
Fig. 3, allowing for ease of access to the gimbal 6 that is mounted between
the inner and
outer retaining flanges 3, 5, for routine maintenance or repairs as may be
required from
time to time. As illustrated in Fig. 3, the flange and gimbal assembly further
comprises
seals 18 engaging grooves in the retaining flanges 3, 5, which are operative
to prevent
leakage of the tank contents past the outer surface of the gimbal 6.
The gimbal b defines a cleaning channel 7 therethrough such that an outer end
of the
cleaning channel 7 is exposed on an outside of the tank, and an inner end of
the cleaning
channel 7 is exposed on an inside of the tank, and through which a wand may be
inserted
to gain access to the interior of the tank. A nipple 17 is threaded into
threads 8 in the
outer end of the cleaning channel 7. The nipple 17 is hollow, and closed at an
outer end
with a gate valve 16.
The gimbal 6, flanges 3, 5, nipple 17 and gate valve 16 are installed on a
tank in place of
the fixed port and gate valve that is conventionally used to attach a cleaning
assembly to
clean sediment from the tank. The conventional cleaning assembly comprises a
hollow
vacuum tube 9, and a pressure wand 14 sealed to the vacuum tube 9 and slidable
along an
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axis of the vacuum tube 9 such that the pressure wand 10 can move in and out
of the tank
along the axis of the vacuum tube 9.
Conventionally, the vacuum tube 9 is threaded into the gate valve 16 and the
valve is
S opened to allow the pressure wand 10 to move into the tank 2. A pressure
truck supplies
high-pressure water to the pressure wand 10 to produce a focused high-pressure
jet 13 of
water through the nozzle 12 which dislodges the sediment 14. The resulting
slurry of
water and sediment is aspirated out through the outer portion of the nipple
17, valve 16,
and vacuum tube 9, around the pressure wand 10, into a vacuum track through
the
vacuum outlet 11. The pressure wand 10 can be pushed through the fixed port to
the
opposite side of the tank 2, dislodging sediment 14 in a strip from the port
to the opposite
wall as illustrated in Fig. 2A.
The adapter apparatus 1 of the present invention provides a swiveling port to
which the
nipple 17 and valve 16 is atxached. The conventional cleaning assembly is
attached to the
valve 16 in the same manner as before, by threading the vacuum tube 9 into the
threads
on the gate valve 16. However the gimbal 6 allows the pressure wand to be
moved not
only in and out, but from side to side and, if desired, up and down, allowing
sediment 14
in the much larger area shown in Fig. 2B to be removed.
The valve 16 and nipple 17 can cvnveruently be mounted on a pivoting support
arm 15.
The support arm 15 serves to keep the tube 9 in a substantially horizontal
orientation,
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while still permitting a side to side motion of the pressure wand, such that
the pressure
wand 10 is placed in a position suited for efficient cleaning of the tank
bottom. Mounting
the tube 9 on the support arm 15 provides relief for the operator, such that
the operator is
not required to manually control the tube 9. Typically when cleaning such
tanks it is not
desirable to have the nozzle 12 drag or rub along the tank floor, causing
wear. As well
when using the illustrated gimbal 6 that allows movement vertically as well as
horizontally the pressure wand 10 tends to rise as it encounters sediment, and
it is
necessary to hold the nozzle end down. The support arm 15 thus limits vertical
movement of the pressure wand 10, decreasing the effort that must be expended
by an
operator when using the cleaning system.
With the support arm 15 removed, the gimbal 6 can be moved up and down as well
as
side to side. Figs. 3 and 4 illustrate an alternate device for limiting
vertical movement of
the nipple 17, and thus the attached valve and vacuum tube. Upper and lower
stop plates
20 are fixed to the outer retaining flange 5 such that the nipple 17 extends
between the
stop plates 20 and vertical movement thereof is limited. In the illustrated
embodiment
the stop plates 20 are welded to the outer retaining flange 5 and so this
particular device
will only be used where it is contemplated that vertical movement will not be
required at
any time. Alternatively the stop plates 20 could be attached to the outer
retaining flange
5 by bolts or like fasteners.
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Although the spherical gimbal 6 and cooperating retaining flanges 3, 5 are
convenient
and economical to manufacture, other shapes for the swiveling body and swivel
support
could provide the required function as well. For example a vertically oriented
cylindrical
or oblong body evuld be substituted for the spherical gimbal 6, and suitably
sealed to the
tank wall 2 suds that side to side movement is available, but up and down
movement is
prevented.
Thus the invention provides a swiveling body defining a cleaning channel
therethrough,
for example ss illustrated as gimbat b. The swiveling body is sealed in a
lower portion of
the tank wall such that the swiveling body may move at least horizontally and
such that
an outer end of the cleaning channel is exposed on an outside of the tank, and
an inner
end of the cleaning channel is exposed on as inside of the tank, for example
as illustrated
by the swivel support device comprising retaining flanges 3, 5. A valve is
operative to
close the cleaning channel and has a first port connected to the outer end of
the cleaning
channel and a second port adapted for connection to a tube from a vacuum truck
in a
conventional manner, as illustrated by gate valve 16 and nipple 17. V~hen the
vacuum
tube is connected the valve can be opened, and the tank cleaned by pushing the
pressure
wand through the valve and the cleaning channel into the tank and pushing the
pressure
wand back and forth and substantially horizontally from side to side while
directing a
flow of pressurized water through the pressure wand and drawing a sediment
slurry out of
the tank through the vacuum tube.
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The foregoing is considered as illustrative only of the principles of the
invention.
Further, since numerous changes and mod~cations will readily occur to those
skilled in
the art, it is not desired to limit the invention to the exact construction
and operation
shown and described, and accordingly, all such suitable changes or
modifications in
structure or operation which may be resorted to are intended to fall within
the scope of
the claimed invention.
