Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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This invention relates to apparatus and
methods of storing two liquids of different densities in
contact with each other in the same storage tank and the
simultaneous removal of one of the liquids from the tank
while the other liquid is fed into the tank.
Background of the Invention
It is recognized as useful to be able to store
two liquids of different density under conditions which
maintain them essentially separate, even when the compo-
sition of both liquids is identical. Such separation
can be achieved by two independent vessels, a single
vessel with internal compartmentalization, a vessel with
simple or labyrinthine fixed baffles, a vessel with a
movable rigid baffle or a vessel with a flexible
diaphragm or membrane. Such systems, however, have
technical, operational or economic drawbacks.
A more desirable system is to maintain
separation of the two different density liquids as
separate layers by stratification with the lower density
liquid layer above the higher density liquid layer.
Even though the density of the two liquids is different,
they have the same composition. This can occur because
the density of the liquid used increases as its temper-
ature decreases and the density decreases as its temper-
ature increases. Examples of such liquids, at least
over some of the most useful temperature ranges, are
water, aqueous solutions of organic liquids such as
methanol and ethylene glycol, aqueous solutions of
inorganic salts such as sodium chloride, carbon dioxide,
oil and molten salts. Such liquids are stored in
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stratified layers as sources of thermal energy and for
refrigeration and for cooling purposes. See, for
example, the U.S. patents of Haynie 4,449,368; Schmitt
et al 4,315,404; and Rothrock 4,643,212.
When the lower cold layer is used for
refrigeration or cooling, a stream of the cold liquid is
withdrawn, used for cooling and then returned warm or
hot, and at a lower density, to the top layer while cold
liquid is simultaneously removed from the bottom
layer. In this way, essentially the entire stored
volume can be used for cooling so that the entire liquid
content returned to the tank becomes heated. At an
appropriate time the warm or hot liquid can be withdrawn
from the tank and cooled and then returned to the tank
as a lower stratified cold layer of higher density with
a hot layer of lower density on top unless, of course,
cooling continues until all of the hot liquid in the
tank is withdrawn and returned as cold liquid.
Maintaining the described stratification of
the two liquid layers having different densities
requires that the liquids be withdrawn and fed to the
tank without promoting undue mixing at the tank inlet
and outlet and at the interface of the two liquids. The
desired result can be achieved by the use of manifolds,
usually including a myriad of nozzles. ports, holes,
slots, perforations or other openings, but they have
been determined to be cumbersome and costly in fabri-
cation, support, erection and maintenance. Accordingly,
there is a need for simpler apparatus and methods for
storing such stratified liquids in a tank and then
simultaneously removing liquid of one density from the
tank while feeding liquid of a second density to the
tank.
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SUMMARY OF THE INVENTION
According to the invention an enclosed storage
tank for the simultaneous addition and removal, and
storage, of two liquid layers of different density is
provided comprising a tank shell having a bottom, a side
wall extending upwardly from the bottom, a roof
supported at least in part by the side wall and by at
least one vertical tubular column extending upwardly
from the shell bottom to at least close to the roof; a
substantially horizontal first distributor plate above
which the column extends and with the plate spaced above
but adjacent to the shell bottom; first opening means in
the column between the first distributor plate and the
shell bottom; a high density liquid conduit extending
from outside the shell into communication with the
column interior whereby high density liquid can be fed
to the column interior and then flow out the first
opening means into the lower portion of the tank beneath
the first distributor plate and the nigh density liquid
can be withdrawn from the tank through the first opening
means and then through the high density liquid conduit;
a substantially horizontal second distributor plate
above and below which the column extends and with the
second distributor plate spaced below but adjacent to
the shell roof; second opening means in the column
between the second distributor plate and the shell roof;
a low density liquid conduit extending from outside the
shell into communication with the column interior
whereby low density liquid can be fed to the column
interior and then flow out the second opening means into
the upper portion of the tank above the second
distributor plate while high density liquid is withdrawn
from the tank through the high density liquid conduit,
and the low density liquid can be withdrawn from the
tank through the second opening means and then through
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the low density liquid conduit while the high density
liquid is fed to the tank through the high density
liquid conduit.
Both the first and second distributor plates
can be circular.
The first opening means and the second opening
means can include openings or ports substantially
uniformly spaced around the column periphery. Also, the
column can be circular in horizontal section.
A bulkhead can be positioned inside the column
to prevent the low density liquid from contacting the
high density liquid in the column.
A horizontal vortex breaker plate, through
which the column extends, can be positioned above, but
adjacent to, the second opening means.
The enclosed storage tank can have a pre-
determined minimum liquid storage capacity which places
the liquid level above the second opening means.
The high density liquid conduit can com-
municate with the column below the bulkhead and the low
density liquid conduit can communicate with the column
above the bulkhead.
The tank shell can be made of metal or wholly
or partly of non-metallic material, and the bottom can
be flat and circular, the side wall can be cylindrical
and circular in section and the roof periphery can be
circular.
In use the tank can be filled to at least a
minimum storage capacity with a top layer of a low
density liquid and a bottom layer of a high density
liquid and the two liquids can have the same composition
but be at different temperatures.
The invention also provides a method for
simultaneously adding and/or withdrawing low density and
high density liquids from the tank.
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BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a side elevational view, partially
broken away and in section, of one embodiment d~ a
storage tank provided by the invention;
Figure 2 is a side elevational view, partially
broken away and in section, of a second embodiment of a
storage tank provided by the invention;
Figure 3 is an enlarged elevational view of
the central portion of the storage tank shown in Figure
2;
Figure 4 is a sectional view taken along the
line 4-4 of Figure 3;
Figure 5 is a sectional view taken along the
line 5-5 of Figure 4; and
Figure 6 is a sectional view taken along the
line 6-6 of Figure 5.
DETAILED DESCRIPTION OF THE DRAWINGS
To the extent it is reasonable and practical
the same or similar elements which appear in the various
drawing figures will be identified by the same numbers.
Figure 1 illustrates an enclosed storage tank
10 supported on a foundation or ground 12. The tank has
a flat circular metal bottom 14 and a circular
cylindrical side wall 16 and a conical roof 18 which is
supported by beams 20 which have their inner ends
supported by ring 22 on the upper portion of column
30. An overflow outlet pipe 24 is positioned in the top
of side wall 16 slightly above the maximum liquid
storage capacity of the tank.
The column 30 has a circular base plate 32
mounted on the center of tank bottom 14. The column 30
is a vertical hollow tube which is circular in hori-
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zontal section. Slightly above base plate 32 the column
30 has a plurality of holes or openings 34 which permit
high density liquid 100 to be fed into and out of the
lower part of column 30. Pipe 36 extends from outside
of tank side wall 16 into liquid communication with the
interior lower part 38 of column 30 below baffle plate
40 which extends completely across the interior hori-
zontal area of the column and thereby prevents passage
of liquid past the baffle. High density liquid fed by
pipe 36 into the column lower part 38 flows out holes 34
below a first circular horizontal liquid distributor
plate 42 supported by rods 44 attached to gussets 46
positioned radially on the outside of column 30.
The removal of high density liquid from tank
10 is achieved by having it flow through holes 34 into
column 30 and out through pipe 36. Thus, pipe 36
functions as an inlet pipe and an outlet pipe.
Pipe 50 extends from outside of tank 10 into
liquid communication with the interior part of column 30
above baffle 40. Pipe 50 is used to feed lower density
liquid into, and withdraw it from, the tank 10. When
lower density liquid 200 is fed by pipe 50 into column
the liquid flows upwardly in the column until it
reaches the plurality of radially positioned holes 52.
25 The lower density liquid 200 flows out of the column
through holes 52 into the upper space of the tank but
above the second or upper horizontal circular liquid
distributor plate 54. The second distributor plate is
connected to column 30 and is further supported by rods
30 56 which are joined to radial gussets 58 on the side of
column 30. A horizontal circular vortex plate 60 is
axially mounted on column 30 above the holes 52.
To increase the stored volume of a higher
density liquid 100, which can be cold water, in tank 10
the higher density liquid can be fed into the tank
through pipe 36. Simultaneously, an equal volume of a
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lower density liquid, which can be hot water, is removed
from the tank through pipe 50 while the nominal maximum
liquid capacity of the tank is maintained at level 64
located slightly below overflow outlet 24. By reversing
the described procedure the volume of higher density
water in the tank can be increased.
The described embodiment of the invention uses
the column 30 as the liquid riser or fluid conduit for
the inlet and outlet flow of liquid to and from the dis-
tribution plates. This arrangement uses less material
and is more economical to fabricate and erect than
others which might be used. Another advantage of the
column 30 is that it simultaneously serves to support
roof 18. Furthermore, the primary liquid flow side or
surface of each of the distributor plates 42,54 is
essentially smooth, thus permitting the radial liquid
flow desired for optimum liquid distribution.
The small vortex plate 60 functions as a
liquid vortex breaker when lower density liquid is
withdrawn from the tank and as a splash plate during
addition of lower density liquid, such as warm water.
For insulation purposes the tank bottom 14,
side wall 16 and roof 18 can be externally or internally
insulated. The column 30 can be similarly insulated as
can the internal flow conduits 36 and 50, as well as
baffle 40. Baffle 40, if desired, can constitute two
horizontal vertically spaced apart plates to thereby
obtain an insulating effect. Furthermore, the tank and
all other elements therein can be made wholly ar
partially of non-metallic materials such as poly-
propylene, polyvinylchloride or of a glass fiber-
containing solid polymeric material.
The tank 10 is especially useful for thermal
energy storage of a liquid which changes density with
change in temperature, such as water, salt water,
natural or synthetic oils, molten salts, carbon dioxide,
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lower alcohols such as methanol and ethanol, liquefied
natural gas, liquid hydrocarbons and liquid metals in
pure form or as mixtures. The tank 10 is also useful
for storing two chemically different liquids having
different densities. In both cases, however, the liquid
volumes remain separated by stratification with the
lower density liquid volume stratified on top of the
higher density liquid volume.
With reference to the second embodiment of the
invention as illustrated in Figures 2 to 6, the tank 70
is supported on a foundation or earth 12. The tank 70
also has a flat circular metal bottom 14, a circular
cylindrical side wall 16 and a conical roof 18 which is
supported by radial beams 20 which have their inner ends
supported by ring 22 on the upper portion of vertical
column 80. The column 80 is mounted in alignment with
the vertical center of tank bottom 14. An overflow
outlet pipe 24 is positioned in the top of side wall 16
of tank 70 at the maximum liquid storage capacity of the
tank.
Beneath the lower end of column 80, and
mounted on the upper surface of tank bottom plate 14, is
a circular base plate 82 in contact with plate 14. A
series of eight radially positioned vertical plates 84
extend outwardly from the vertical axis of column 80
which is also the vertical axis of the tank. Adjacent
plates 84 are angularly equally spaced apart. Circular
horizontal plate 86 is supported on the top of radial
vertical plates 84. A circular axially located hole 88
(Figure 5) is located in circular plate 86 so as to
provide liquid communication between the column 80
internal lower space and the column external space.
A circular ring plate 90 is axially mounted on
top of plate 86. The ring plate 90 has a circular hole
88 (Figure 5) with a diameter somewhat less than the
outer diameter of circular plate 86 thereby providing
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supporting contact between the two plates. Each hori-
zontal ring plate 90 is fabricated from either
identically sized and shaped plates 92, each in the
general shape of a sector of a circle. The two radial
edge portions 94 of each circular sector plate 92 are
bent vertically upwardly and the adjacent edge portions
94 of each circular sector 92 are joined together by
bolts 96. The ring plate 90 can be provided with
hatches or other closeable openings to permit access
below the plate for inspection, painting and other
maintenance.
Eight equally spaced apart vertical bars 98
are joined along the perimeter of circular plate 86.
Each bar 98 fits into a slot on the inner edge of a
circular sector 92. The bar 98 is then joined to the
respective circular sector 92.
Eight equally spaced apart bars 108 (Figure 5)
are coated around the perimeter of ring plate 90. The
lower end of an angle bar brace 110 is bolted to each
bar 108 and the upper end of each brace 110 is bolted to
one of the gussets 112 on the column tubular portion
120.
Plate 86 and the ring plate 90 fabricated as
described together constitute a liquid distributor plate
and the combination of vertical plates 84, plate 86 and
ring plate 90 constitute a liquid vortex breaker.
The column 80 includes a lower tubular portion
114 which rests on plate 86. A reducing Tee 118 is
joined to the top of tubular portion 114 (Figure 3).
Horizontal circular wall plate 40 is positioned in the
upper part of Tee 118 to prevent liquid flow in either
direction past the plate. Liquid conduit pipe 36 is
connected to the side opening of Tee 118. The column
tubular portion 120 is joined to the top of Tee 118 and,
in turn, Tee 122 is joined to the top of tubular portion
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120. Liquid conduit pipe 50 is connected to the side
opening of Tee 122 (Figure 3).
Column 80 tubular portion 124 is joined at the
bottom to the top of Tee 122. Circular plate 1'26 is
mounted axially and horizontally on the top of column
portion 124 (Figure 3). Plate 126 is provided with a
centrally located circular hole 127 slightly smaller
than the internal diameter of column portion 124. Eight
radially positioned and angularly equally spaced apart
vertical plates 128 are joined to the top of plate
i26. Circular horizontal plate 130 is axially
positioned, with respect to tubular portion 124, on top
of and is joined to the vertical plates 128.
Column tubular portion 132 is axially joined
to the top of plate 130. A circular plate 134, joined
to the top of column tubular portion 132, closes off the
top of the column. The roof supporting ring 22 and
associated structure is in turn joined to, and supported
by, plate 134. Vent pipe 136 is centrally mounted in
the tank roof 18 and it communicates with the tank upper
interior space and the exterior atmosphere.
A horizontal ring plate 140 (Figures 3 and 4)
is axially positioned and joined to the bottom perimeter
of plate 126. The plate 140 can be fabricated or
assembled from eight identically sized and shaped plates
142, each in the general shape of a sector of a
circle. The adjacent radial edges of a pair of
adjoining sector plates 142 are supported by a radially
positioned angle member 144 (Figures 4 and 6).
The horizontal ring plate 140 can be supported
by eight braces 146. The upper end of each brace 146 is
connected to an angle member 144 and the lower end of
the brace 146 is connected to a gusset 148 joined to
column tubular section 124.
The circular plate 130 functions as a splash
plate when liquid is supplied to the tank by means of
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pipe 50. When liquid is withdrawn from the tank by
means of either pipe 36 or 50 the plates 126, 130 and
128 in combination function as a vortex breaker. Plate
126 and ring plate 140 taken together also function as a
S distributor plate when liquid is fed to the tank through
pipe 50 and column 80.
It will be seen that the second embodiment of
the invention eliminates use of the holes 34 and 52
present in the first embodiment (Figure 1) to supply
liquid to the tank and to remove liquid from the tank.
The liquid feed and removal means in the upper part of
the tank comprising plates 126, 128, 130, and in the
lower part of the tank comprising plates 82, 84, 86,
give a more uniform radial flow of liquid than does the
use of holes 34, 52 in the first embodiment (Figure 1).
The operation of the second embodiment of the
invention as illustrated by Figures 2 to 6 is
essentially the same as for the first embodiment
illustrated by Figure 1 and which has been previously
explained herein. That explanation can be referred to
thus making it unnecessary to repeat it again.
It is also within the scope of the invention
to use a plurality of columns in a tank and to provide
each column with apparatus as described above in respect
to the first and/or second embodiments of the invention:
Any and all of parts of the tank can be
thermally insulated and also many parts can be
fabricated of insulating construction materials,
especially the columns-30, 80, feed pipes 36, 50, bulk-
heads 40, braces 110, 146 and plates 82, 84, 86, 92 as
well as plates 126, 128, 130 and 142.
The foregoing detailed description has been
given for clearness of understanding only, and no un-
necessary limitations should be understood therefrom, as
modifications will be obvious to those skilled in the
art.
