Note: Descriptions are shown in the official language in which they were submitted.
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FLOATING COVER SYSTEM FOR LARGE OPEN CONTAINERS
This invention is in the field of liquid storage and in particular large
liquid tanks,
containers, reservoirs and the like with open tops containing liquid such as
are used for
heating large quantities of water for formation fracturing in the petroleum
recovery and
like industries, and also for storing large quantities of water in dry
climates where
evaporation is problematic.
BACKGROUND
In some mining, industrial, and agricultural applications, very large
quantities of liquid
are required to be stored. For example in petroleum oil and gas recovery
operations, it is
common practice to fracture an underground formation by injecting liquid at
high
pressure into the formation. Fracturing operations, commonly called fracking,
can
require very large amounts of heated liquid, which must be stored and heated
in a
temporary container typically a tank or pit set up at the work site. Some of
the these
tanks can be twelve to fourteen feet high, and 150 or more feet across, and
contain two
million gallons of liquid.
Frack tanks are transported to the work site where they are set up and filled
with liquid
that typically must be heated to a desired temperature for use in the fracking
operation.
Because of their large size, it is not practical to close the tops of the
tanks and so they are
open, such that very significant heat loss occurs from the large exposed top
surface of the
water as it is being heated. Also in hot summer temperatures a significant
amount of
water can be lost to evaporation.
The liquid used in fracking operations is water mixed with a variety of
chemicals. Once
erected, the frack tank is filled by hauling or pumping water from a river or
the like, and
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this filling operation can take three to four days. The water is heated during
and/or after
filling by large mobile heating units, and once heated the water is used
within a day or so,
unless there are operational delays, which may result in needing to reheat the
water.
With the significant heat losses from the open water surface, it may be
required to add
heat constantly to maintain a satisfactory temperature during use. The large
mobile
heating units are costly and in demand so rentals costs are high and it is
sometimes
difficult to schedule the filling of the tanks to coordinate with the arrival
of the heating
units. The heating operation is therefore costly.
To reduce heat loss and evaporation these tanks can be covered with a flexible
membrane
however wind often makes this process problematic. Canadian Patent Application
Number 2836954 of Bleile et al. discloses a system for securing such membrane
covers.
Floating insulated tank covers are also known. Canadian Patent Application
Number
2,832,802 of Hindbo discloses a cover for large frack tanks comprising a
plurality of
inflatable bladders that are shaped generally like pie slices, and tied
together. The
bladders are also connected by an air channel such that pressurized air can be
continuously pumped into each of the bladders to keep them inflated.
Other floating tank covers are disclosed for example in United States Patent
Numbers
7,240,804 to King et al., 6,922,956 to Johnson, et al., and 5,704,509 to
Rosenkrantz.
In other industries, containers, reservoirs or open pits are covered in dry
climates to
preserve water and substantially reduce evaporation losses when it is used for
livestock or
industrial uses.
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SUMMARY OF THE INVENTION
The present disclosure provides a floating cover system for tanks, open pits,
or like
containers that overcomes problems in the prior art.
The present disclosure provides a floating cover system for a container with
an open top.
The system comprises a plurality of cover sections, each cover section adapted
to float on
a water surface, and a plurality of cover connector devices attached to, and
equally
spaced along, a periphery of each cover section at a connector spacing. A
ballast tube has
a plurality of tube connector devices attached to, and equally spaced along, a
length of an
exterior of the ballast tube at the same connector spacing. The ballast tube
is open at
each end thereof such that water enters an interior of the ballast tube
through the open
ends thereof The cover sections are configured such that when all the cover
sections are
installed in the container, the open top of the container is substantially
covered by cover
sections joined together at seams where adjacent cover connector devices are
connected
together, and the tube connectors are connected to the cover connectors along
a ballast
seam such that the ballast tube is located under the ballast seam.
The presently disclosed floating cover system is highly resistant to wind
forces which can
be significant depending on the location of the container. The system is also
convenient
to transport and can be readily installed on the floor of an empty container,
or can be
installed on a filled container if The system is also readily transportable
and adaptable to
different sizes of containers.
DESCRIPTION OF THE DRAWINGS
While the invention is claimed in the concluding portions hereof, preferred
embodiments
are provided in the accompanying detailed description which may be best
understood in
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conjunction with the accompanying diagrams where like parts in each of the
several
diagrams are labeled with like numbers, and where:
Fig. 1 is a schematic top view of an embodiment of a floating cover system of
the
present disclosure installed in a container with an open top;
Fig. 2 is a schematic sectional side view along line 2-2 in Fig. 1;
Fig. 3 is a schematic top view of a rectangular cover section attached to an
edge cover
section in the embodiment of Fig. 1;
Fig. 4 is a perspective end view of the open end of a ballast tube of the
embodiment of
Fig. 1;
Fig. 5 is a schematic top view of the fabric strip, connector rings and weight
member
attached along a periphery of a cover section;
Fig. 5A is a schematic end view of the connector rings of one cover section
attached to
the connector rings of an adjacent cover section in the embodiment of Fig. 1,
with the
fabric strips weighted down into the water by a cable, chain, or the like;
Fig. 6 is a schematic top view of the embodiment of Fig. 1 installed in a
container with
a smaller diameter than the container of Fig. 1;
Fig. 7 is a schematic top view of the embodiment of Fig. 1 installed in a
container with
a smaller diameter than the container of Fig. 6;
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Fig. 8 is a schematic end view of an inflatable cover section of the
embodiment of Fig.
1 showing the attachment of the ballast tube;
Fig. 9 is a schematic sectional view along line 9-9 in Fig. 8;
Fig. 10 is a schematic sectional view of the resilient air tight section tubes
and fabric
shell of the inflatable cover section of Fig. 8;
Fig. 11 is a schematic sectional view showing the construction of a cover
section made
from a floating sheet material covered by a fabric material;
Fig. 12 is a schematic side sectional view of a cover sheet comprising a
flexible bubble
sheet with air bubbles defined on the bottom surface thereof.
DETAILED DESCRIPTION OF TIIE ILLUSTRATED EMBODIMENTS
Figs. 1 and 2 schematically illustrate an embodiment of a floating cover
system 1 of the
present disclosure installed in a container 3 with an open top 5. The system 1
comprises
a plurality of cover sections 7, each cover section 7 adapted to float on a
water surface.
Cover connector devices 9 are attached to, and equally spaced along, a
periphery of each
cover section 7 at a connector spacing CS, as shown in Fig. 3.
A ballast tube 11, as shown in Fig. 4, has a plurality of tube connector
devices 13
attached to, and equally spaced along, a length of an exterior of the ballast
tube 11 at the
connector spacing CS. The ballast tube 11 is open at each end thereof such
that water
enters an interior of the ballast tube 11 through the open ends 17 thereof
Longer ballast =
tubes 11 further define a plurality of access holes 15 spaced along a length
thereof such
that water enters the interior of the ballast tube 11 through the open ends 17
thereof and
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the access holes 15. In these longer tubes as well, the access holes 15 allow
air to be
pushed out of the ballast tube 11 by water flowing into the ballast tube 11
from each open
end.
The cover sections 7 are configured such that when all the cover sections 7
are installed
in the container 3, the open top 5 of the container 3 is substantially covered
by cover
sections 7 joined together at seams 19 where adjacent cover connector devices
9 are
connected together, and the tube connectors 13 are connected to the cover
connectors 9
along a ballast seam 19A such that the ballast tube 11 is located under the
ballast seam
19A.
The ballast tubes 11 fill with water and anchor the cover sections 7 along the
ballast
seams 19A. As shown in Fig. 1, the ballast seams 19A, with the ballast tubes
11
suspended below them, are placed at locations that are selected depending on
the strength
of winds expected, the direction of the prevailing winds, and like
considerations.
The cover connector devices are conveniently provided by connector rings 21 as
schematically illustrated in Fig. 5 and 5A. Conveniently the connector rings
21 are
attached to a fabric strip 23 and the fabric strip 23 is attached along the
periphery of each
cover section 7. Adjacent connector rings 21 on adjacent cover sections 7 are
connected
together by a tie member, such as a carabiner 25 or like metal loop with a
spring-loaded
gate.
To reduce the occurrence of wind entering under the edges of the cover
sections 7 an
inner edge 23A of each fabric strip 23 is attached along the periphery of the
corresponding cover section 7, and the connector rings 21 are attached in
proximity to the
inner edges 23A of the fabric strips 23 such that the fabric strips 23 extend
outward from
the connector rings 21. Conveniently the connector rings 21 are attached to a
fabric tape
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23C which can be readily sewn onto the fabric strips 23. When placed in the
water the
outer edges 23B of the fabric strips 23 hang down in the water where the wind
cannot get
under them. A weight member 23D, such as a chain, cable, weighted rope, or the
like,
can be attached along the outer edge 23B of the fabric strips 23 to ensure
same sink into
the water.
Conveniently the system comprises a plurality of rectangular cover sections 7A
with the
same dimensions, and wherein each rectangular cover section 7A has a width
dimension
W and a length dimension L substantially equal to twice the width dimension W.
The
fabric strip 23 is attached along each edge of each rectangular cover section
7A such that
a connector ring 21 is located at each corner 27 of each rectangular cover
section 7A, and
the connector spacing CS is an even multiple of the width dimension W. It is
contemplated for example that a rectangular cover section 7A with a width
dimension of
18 feet, a length dimension of 36 feet, and a connector spacing of three feet
will allow for
convenient covering of a variety of tank sizes. Other dimensions can be used
depending
on circumstances.
The container 3 comprises a substantially cylindrical wall 29 and the open top
5 is
circular. The cover sections 7 include a plurality of rectangular cover
sections 7A, and a
plurality of edge cover sections 7B that are configured to substantially cover
edge areas
of the open top 5 between the rectangular cover sections 7A and the
cylindrical wall 29
when the cover sections 7 are installed. The cover sections 7 are also
configured such
that when all the cover sections 7 are installed as shown in Fig. 1, a small
space 31 is
formed between the cover sections 7 and the wall 29 such that the cover
sections 7 not
tight against the wall 29 and so are able to move up and down as a level of
water 33 in
the container 3 moves up and down.
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Figs. 1 and 2 schematically illustrate the system 1 in use on a first
container 3 with a
circular top 5 with a first diameter Dl. Fig. 6 schematically illustrates the
system 1 in use
on a second container 3' with a circular top 5' with a second diameter D2
smaller than the
first diameter Dl. The system 1 thus comprises a plurality of rectangular
sections 7A
with the same dimensions as illustrated in Fig. 3, a plurality of first edge
cover sections
7B configured to substantially cover edge areas of the open top 5 between the
rectangular
cover sections 7A and the cylindrical wall 29 when the cover sections 7 are
installed in
the first container 3, and a plurality of second edge cover sections 7C
configured to
substantially cover edge areas of the open top 5' between the rectangular
cover sections
7A and the cylindrical wall 29' when the cover sections 7 are installed in the
second
container 3'.
Fig. 7 schematically illustrated a third container 3" with a circular top 5"
with a third
diameter D3 smaller than the second diameter D2. Here the system includes a
plurality
of third edge cover sections 7D configured to substantially cover edge areas
of the open
top 5" between the rectangular cover sections 7A and the cylindrical wall 29"
when the
cover sections 7 are installed in the third container 3". It can be seen that
by using a
standard rectangular sheet section 7A, virtually any diameter container can be
covered by
providing edge cover sections configured for a particular size open top.
As seen in Fig. 4, the tube connector devices 13 are provided by a flap 35
extending from
the ballast tube 11 and a connector hole 37 defined in the flap 35. As can be
seen in Fig.
8 the connector holes 37 are aligned with the cover connector devices 9, such
as rings 21,
attached along each cover section 7 at the same connector spacing, such that
the tie
member passes through the connector holes connected to adjacent connector
rings 21
along the ballast seams 19A by the carabiner 25. Conveniently the flap 35 is
continuous
along the exterior length of the ballast tube 11 and the holes 37 are spaced
along the flap
at the connector spacing CS.
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The ballast tube 11 could be made of a rigid material however to facilitate
transport the
ballast tube 11 is conveniently formed from a flexible fabric material with a
stiff ring 39
attached at each open end 17 thereof The stiff ring 39 holds the fabric
material open
such that water flows into each open end 17 of the ballast tube 11. When
filled with
water the ballast tube 11 resists upward movement of the attached cover
sections 7 and
prevents them from blowing away.
Figs. 8 - 10 illustrate cover sections 7 that are inflatable. Each cover
section 7 comprises
a plurality of flexible and resilient air tight section tubes 41, as seen in
Fig. 9, each
defining a closable air filling orifice 43. The sections tubes 41 are joined
together to
form each cover section 7 by a fabric shell 45 comprising an upper sheet of
fabric shell
material 45A and a lower sheet of fabric shell material 45B that holds the
tubes 41
together and also defines the diameter of the tubes 41 which will stretch when
inflated.
The upper and lower sheets of fabric shell material 45A, 45B are joined
together between
adjacent section tubes 41, as shown in Fig. 10, s by sewing, adhesives, or the
like. The
cover sections 7 can conveniently be deflated and folded for transport at one
work site,
then unfolded and inflated at the next work site. Inflation pressures are low,
simply
enough to maintain the shape of the caver sections 7.
Fig. 11 schematically illustrates a cover section 7' comprising a sheet of
flexible foam
material 47 encased in a fabric material 49 with connector rings 21 attached
to the
periphery thereof The flexible foam and fabric cover allows the cover sections
to be
rolled into a compact shape for transport.
The cover sheets can also be provided by flexible bubble sheets 51 with air
bubbles 53
defined on the bottom surface 51A thereof as schematically illustrated in Fig.
12. The
bubbles 53 provide an enlarged surface area in contact with the water surface
when the
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bottom surface of the sheet 51 is laid on the water surface. It is
contemplated that this
will increase the resistance of the bubble sheets 51 to lifting off the water
surface.
The inflatable cover sections 7 and sheet material cover sections 7' are
typically only 1/4
inch to one inch thick depending on the material used, with a ballast tube
diameter of for
example about one foot for cover sections that are 18 feet by 36 feet.
The floating cover system 1 of the present disclosure is highly resistant to
wind forces
which can be significant depending on the location of the container. The
system 1 is
convenient to transport and can be readily installed on the floor of an empty
container, or
can be installed on a filled container if necessary by floating the cover
sections out over
the water surface as they are attached, with some assistance likely required
by a person
floating on the surface as well. The system 1 is also readily transportable
and adaptable
to different sizes of containers.
The foregoing is considered as illustrative only of the principles of the
invention.
Further, since numerous changes and modifications 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.
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