Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE OF THE INVENTION:
Low Temperature Heating System for a Hydrocarbon Storage
Tank
FIELD OF THE INVENTION
The present invention relates to a low temperature
heating system for a hydrocarbon storage tank
BACKGROUND OF THE INVENTION
Hydrocarbon storage tanks in use in the oil industry
commonly use a fire tube as a heat source. A fire tube is a
tube that extends through the storage tank. Each end of the
fire tube is accessible from outside the storage tank. A
burner is externally mounted at one end of the fire tube. As
the name °'fire tube" implies, a flame from the burner is
directed into the tube.
It will be understood that the use of a fire tube
distributes heat unevenly in the storage tank. Hydrocarbons
in close proximity to the flame receive more heat than
hydrocarbons at a distance from the flame. It has recently
been determined that product in the storage tank in close
proximity to the flame is invariably subjected to excessive
heat from the fire tube. This excessive heat adversely
affects the product and makes additional processing
necessary. The change in the hydrocarbons as a result of
excessive heat, has been compared to the change in an egg
when subjected to heat.
S'U1~1ARY OF THE INVENTION
What is required is a low temperature heating system for
a hydrocarbon Storage tank that will not adversely affect the
stored hydrocarbons.
According to the present invention there is provided a
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low temperature heat3_ng system for a hydrocarbon storage tank
which includes a storage tank with several open face tubular
helical coils disposed within the storage tank. Each helical
coil has an inlet end and an outlet end. Means are provided
for circulating heated heat transfer fluids through each the
helical coils, whereby heat is transferred from the heat
transfer fluids in the helical coils to liquids in the tank.
Heating the storage tank by circulating heated fluids
through the helical coils has proven to be an effective low
temperature heating system. Enough helical coils are used to
ensure adequate heat is generated within the storage tank.
The larger heating surface allows the storage tank to be
heated at a lower heating temperature.
Although beneficial results may be obtained through the
use of the low temperature heating system, as described
above, even more beneficial results may be obtained when the
means for circulating the heated fluid through the helical
coils includes at least one heat exchanger having a first
inlet, a first outlet, a first fluid circulation path
extending from the first inlet to the first outlet, a second
inlet, a second outlet and a second fluid circulation path
extending from the second inlet to the second outlet. A
closed loop circulation conduit connects the outlet end of
the at least one heat exchanger with the inlet end of each of
the helical coils, and the outlet end of each of the helical
coils to the first inlet of the at least: one heat exchanger,
such that heat transfer fluids are heated as they pass along
the first fluid circulation path of the at least one heat
exchanger. A pump is connected to the closed loop circulation
conduit and adapted to circulate heat transfer fluids through
the closed loop circulation conduit. An engine is provided
with an engine fluids conduit communicating with the second
inlet. Hot engine fluids produced by the engine are passed
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along the second fluid path of the at least one heat
exchanger, whereby a heat transfer occurs between the hot
engine fluids passing along the second fluid path and the
heat transfer fluids passing along the first fluid path. The
low temperature heating system, as described above, can be
heated with exhaust gases from the eng~_ne, engine coolant or
both.
It is preferred that some means be provide to
accommodate expansion and contraction of the heat transfer
fluids circulating within the closed loop circulation
conduit. Even more beneficial results may, therefore, be
obtained when the closed loop circulation conduit has an
expansion tank adapted to receive excess heat transfer fluids
from the closed loop circulation conduit resulting from
expansion brought about by increased temperatures. Even more
beneficial results may be obtained when the closed loop
circulation conduit has a make up tank adapted to inject
additional heat transfer fluids into the closed loop
circulation conduit resulting from a contraction brought on
by decreases in temperature.
Although the helical coils can be laid on their sides,
the best results have been obtained when the helical coils
are placed in a vertical orientation. It is preferred that
the helical coils are positioned off the bottom of the
storage tank, extending upwardly from a hydrocarbon/water
interface zone.
It is possible to use different helical coil
configurations. For example, helical coils can be
constructed which have an inner coil and a concentric outer
coil, in order to increase the surface area available for
heat transfer.
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BRIEF DESCRIPTION OF THE DRAWINGS
These and other features of the invention will become
more apparent from the following description in which
reference is made to the appended drawings, the drawings are
far the purpose of illustration only and are not intended to
in any way limit the scope of the invention to the particular
embodiment or embodiments shown, wherein:
FIGURE 1 is a schematic diagram of a low temperature
heating system for a hydrocarbon storage tank constructed in
accordance with the teachings of the present invention.
FIGURE 2 is a side elevation view, in section, of a
hydrocarbon storage tank represented in FIGURE 1.
FIGURE 3 is a top plan view of a hydrocarbon storage
tank represented in FIGURE 1.
FIGURE 4 is a top plan view of an alternative form of
helical coil having a inner coil and a concentric outer coil.
FIGURE 5 is a top plan view of a hydrocarbon storage
tank represented in FIGURE 1 showing coils in pairs.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The preferred embodiment, a low temperature heating
system for a hydrocarbon storage tank generally identified by
reference numeral 10, will now be described with reference to
FIGURES 1 through 5.
Structure and Relationship of Parts:
Referring to FIGURE 1, low temperature heating system 10
includes a closed loop circulation conduit 12 fluidly
connected to a pump 14, an exhaust gas heat exchanger 16, an
engine fluids heat exchanger 18 and a storage tank 20. Closed
loop circulation conduit 12 is further adapted with expansion
tank 22 having exit valve 24 and make up tank 26 having inlet
valve 28. An engine 30 is provided with radiator 32, engine
fluids conduit 34, exhaust manifold 36 and exhaust gases
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conduit 38. A thermostatically controlled diverter valve 39
directs fluid along engine fluids conduit 34 to either
radiator 32 or back to engine 30. Storage tank 20 contains
several open face tubular helical coils 40. Each of exhaust
5 gas heat exchanger 16 and engine fluids heat exchanger 18
have a first inlet 42, a first outlet 44, a first fluid
circulation path 46 extending from first inlet 42 to first
outlet 44, a second inlet 48, a second outlet 50 and a second
fluid circulation path 52 extending from second inlet 48 to
second outlet 50. Each of second fluid circulation paths 52
is positioned in optimum proximity for heat exchange within
each of exhaust gas heat exchanger 16 and engine fluids heat
exchanger 18 respectively. Referring to FIGURES 2 and 3, each
of several open facE: tubular helical coils 40 has an inlet
end 54 and an outlet end 56. Each of several open face
tubular helical coils 40 is oriented off bottom of storage
tank 58, extending vertically upward from a hydrocarbon/water
interface zone 60 to top of storage tank 62. Storage tank 20
is further adapted with coil supports 64. It will be
appreciated that other configurations of open face tubular
helical coils 40 are possible. Referring to FIGURE 4, in the
illustrated embodiment, open face tubular helical coils 40
are inter-wound with a concentric outer coil 66. Referring
to FIGURE 5, open face tubular helical coils 40 are
configured within storage tank 20 in pairs 68.
Operation:
The use and operation of Low Temperature Heating System for a
Hydrocarbon Storage Tank generally referred to as numeral 10,
will now be described with Reference to FIGURES 1 through 5.
Referring to FIGURE 1, several open face tubular helical
coils 40 within storage tank 20, expansion tank 22 having
exit valve 24, make up tank 26 having inlet valve 28, exhaust
gas heat exchanger 16 and engine fluids heat exchanger 18 are
all positioned serially along closed loop circulation conduit
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12. Fluid within closed loop circulation conduit 12 is moved
in a circulation loop by pump 14 which is also in series
along closed loop circulation conduit 12. To uniformly heat
hydrocarbons within storage tank 20, engine 30 is operated at
normal operating temperature. Hot. exhaust gases are
channelled from engine 30 through exhaust manifold 36 into
exhaust gases conduit 38. Exhaust gases conduit 38 further
channels hot exhaust gases through second inlet 48 into
second fluid circulation path 52 within exhaust gas heat
exchanger 16 after which hot exhaust gases are vented to the
atmosphere. Where second fluid circulation path 52 within
exhaust gases heat exchanger 16 is in optimum proximity for
heat exchange, heat is transferred to fluid within first
fluid circulation path 46. As pump 14 is operated, fluid
within first fluid circulation path 4~ is propelled out of
exhaust gas heat exchanger through first outlet 44. As the
heated fluid moves along closed loop circulation conduit 12
it enters first fluid circulation path 46 through first inlet
42 of engine fluids heat exchanger 18. Hot engine fluids from
engine 30 flow into engine fluids conduit 34. Engine fluids
conduit 34 further channels hot engine fluids through second
inlet 48 into second fluid circulation path 52 within engine
fluids heat exchanger 18 after which engine fluids proceed to
thermostatically controlled diverter valve 39 where fluid is
directed to radiator 32 if it remains above a pre-set
temperature or directly back to engine 30 by passing radiator
32 if it is below the pre-set temperature. Where second fluid
circulation path 52 within engine fluid:> heat exchanger 18 is
in optimum proximity for heat exchange, further heat is
transferred to already heated fluid within first fluid
circulation path 46. Propelled by pump 14, heated fluid
within first fluid circulation path 46 exits engine fluids
heat exchanger 18 through first outlet 44. As the further
heated fluid moves a:Long closed loop circulation conduit 12
it enters storage tank 20. Referring to FIGURES 2 and 3. as
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heated fluid circulates through each of several open face
tubular helical coils 40 within storage tank 20, hydrocarbons
within storage tank 20 are evenly and uniformly heated. The
open face, helical design is most efficient, providing a
maximum surface area for heat transfer. The vertical
orientation of each of several open face tubular helical
coils 40 creates a convection current or "chimney effect"
that not only serves to break out gases and reduce foam in
heavy gaseous fluids, but also is self washing and less
susceptible to clogging and sand bridging. It will be
appreciated that other variations in number, length, diameter
and pitch of the several open face tubular helical coils 40
may be manifest based upon the needs and conditions in the
field. One such preferred embodiment: is having open face
tubular helical coils 40 inter-wound with concentric outer
coils 66 as shown in FIGURE 4. Another such preferred
embodiment is having open face tubular helical coils 40
configured in pairs 68 as shown in FIGURE 5. Concentric
coils 66 and pairs 68 can merely be added or removed to suit
the heat requirements of a particular installation.
Referring to FIGURE 1, upon heating hydrocarbons within
storage tank 20, fluid within closed loop circulation conduit
12 leaves storage tank 20 and returns to pump 14 to be re-
propelled to at least one of exhaust gas heat exchanger 16 or
engine fluids heat exchanger 18.
In the preferred embodiment, where low temperature
heating system for a hydrocarbon storage tank 10 is subject
to expansion, exit valve 24 releases fluid from closed loop
circulation conduit 12 into expansion tank 22. Inversely, in
the preferred embodiment, where low temperature heating
system for a hydrocarbon storage tank 10 is subject to
contraction, inlet valve 28 introduces fluid into closed loop
circulation conduit 12 from make up tank 26.
In this document, the word "compr:ising" is used in its
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non-limiting sense to mean that items following the word are
included, but items not specifically mentioned are not
excluded. A reference to an element by the indefinite
article "a" does not exclude the possibility that more than
one of the element is present, unless the context clearly
requires that there be one and only one of the elements..
It will be apparent to one skilled in the art that
modifications may be made to the illustrated embodiment
without departing from the spirit and scope of the invention
as hereinafter defined in the Claims.
