U.S. patent number RE28,856 [Application Number 05/489,518] was granted by the patent office on 1976-06-15 for low-loss closed-loop supply system for transferring liquified gas from a large container to a small container.
This patent grant is currently assigned to Cryogenic Engineering Company. Invention is credited to Kenneth R. Leonard.
United States Patent |
RE28,856 |
Leonard |
June 15, 1976 |
Low-loss closed-loop supply system for transferring liquified gas
from a large container to a small container
Abstract
A liquified gas is transferred from a supply tank to a saddle
tank by gravity flow. After a predetermined amount of the liquified
gas has been transferred, gravity flow is stopped and pressure is
equalized between the saddle tank and the container to be filled.
Thereafter, vapor from the container flows into the supply tank
causing liquified gas to flow from the saddle tank into the
container. After the container has received a predetermined amount
of liquified gas, liquid flow ends and pressure is equalized
between the supply and saddle tanks. BACKGROUND OF THE
INVENTION
Inventors: |
Leonard; Kenneth R. (Boulder,
CO) |
Assignee: |
Cryogenic Engineering Company
(Denver, CO)
|
Family
ID: |
26769331 |
Appl.
No.: |
05/489,518 |
Filed: |
July 18, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
083460 |
Oct 23, 1970 |
03710584 |
Jan 16, 1973 |
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|
Current U.S.
Class: |
62/48.2; 220/749;
137/210 |
Current CPC
Class: |
F17C
9/00 (20130101); F17C 2250/01 (20130101); Y10T
137/313 (20150401) |
Current International
Class: |
F17C
9/00 (20060101); F17C 013/00 () |
Field of
Search: |
;220/85VR,85VS ;141/37
;137/210 ;62/54,55 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: O'Dea; William F.
Assistant Examiner: Capossela; Ronald C.
Attorney, Agent or Firm: Griffin, Branigan & Butler
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A low-loss method of filling a container for liquified gas from
a supply system comprising the steps of:
transferring liquid from a first vessel into a second vessel, and
transferring vapor from said second vessel to said first vessel
whereby the pressure between said first and second vessels remains
equalized as said liquid is transferred;
isolating said first vessel from said second vessel;
equalizing the pressure between said second vessel and said
container for liquid gas;
connecting said first vessel to said container for liquified gas to
permit vapor to flow therebetween;
connecting said second vessel to said container for liquified gas
so that said liquid from said second vessel flows into said
container for liquified gas, and maintaining the connection between
said first vessel and said container for liquified gas to permit
vapor from said container for liquified gas to flow into said first
vessel.
2. A low-loss method of filling a container for liquified gas from
a supply system as claimed in claim 1 including the additional step
of:
disconnecting said container for liquified gas from said first and
second vessels.
3. A low-loss method of filling a container for liquified gas from
a supply system as claimed in claim 1 wherein said liquified gas is
liquid oxygen.
4. The method of claim 1 including the step of connecting the vapor
phase of said container to the vapor phase of said second vessel
during said step of equalizing the pressure between said second
vessel and said container.
5. The method of claim 1 including the step of isolating the vapor
phase of said second vessel from the vapor phase of said container
after said step of equalizing the pressue between said second
vessel and said container.
6. A low-loss method of filling a container for liquified gas from
a supply system as claimed in claim 1 wherein said liquid is
transferred from said first vessel into said second vessel by
gravity.
7. A low-loss method of filling a container for liquified gas from
a supply system as claimed in claim 6 wherein said liquified gas is
liquified oxygen.
8. The method of claim 1 including the step of condensing vapors
from at least one of said first and second vessels.
9. The method of claim 8 including the step of returning the
condensate to the liquid phase of at least one of said first and
second vessels.
10. The method of claim 1 including an additional equalization step
after said container is filled wherein the vapor phases of said
first and second vessels are connected to bring the pressure of
said second vessel down to the pressure of said first vessel.
11. The method of claim 10 including the step of condensing vapors
from at least one of said first and second vessels.
12. The method of claim 11 including the step of returning the
condensate to the liquid phase of at least one of said first and
second vessels.
13. A pump-free low-loss supply system for filling a container for
liquified gas comprising:
a supply tank for housing said liquified gas;
an intermediate tank for temporarily storing said liquified
gas;
first interconnecting means for interconnecting said intermediate
tank to said supply tank for allowing liquid to flow from said
supply tank to said intermediate tank and vapor to flow from said
intermediate tank to said supply tank; and
second interconnecting means for interconnecting said intermediate
tank and supply tank to said container so as to allow gas from said
container to flow from said container to said intermediate tank and
thereafter allow liquid from said intermediate tank to flow into
said container while vapor from said container for liquified gas
flows into said supply tank, said liquid being transferred
pump-free from said supply tank to said container.
14. A low-loss supply system for filling a container for liquified
gas as claimed in claim 13 wherein said liquified gas is liquified
oxygen.
15. A low-loss supply system for filling a container for liquified
gas as claimed in claim 13 wherein said intermediate tank is
mounted at a lower elevation than said supply tank whereby liquid
flows from said supply tank to said intermediate tank by
gravity.
16. A low-loss supply system for filling a container for liquified
gas as claimed in claim 15 wherein:
said supply tank includes an input/output vapor line and an
input/output liquid line;
said intermediate tank includes an input/output vapor line and an
input/output liquid line; and,
said first interconnecting means comprises:
a first valve;
a first pipeline for interconnecting said first valve, said
input/output vapor line of said supply tank and said input/output
vapor line of said intermediate tank;
a second valve; and,
a second pipeline for interconnecting said input/output liquid line
of said supply tank, said second valve and said input/output liquid
line of said intermediate tank.
17. A low-loss supply system for filling a container for liquified
gas as claimed in claim 16 wherein said second interconnecting
means comprises:
a third valve;
a fourth valve having first and second terminals on a first side
and first and second terminals on a second side, the first terminal
on said first side connected through an intermediate valve to the
first terminal on said second side and the second terminal on said
first side connected through another intermediate valve to the
second terminal on the second side;
a third pipeline, said third pipeline interconnecting
the input/output liquid line of said supply tank, said third valve
and the first terminal on the first side of said fourth valve;
a fourth pipeline, said fourth pipeline interconnecting the
input/output liquid line of said intermediate tank to the second
terminal on the first side of said fourth valve; and,
a fifth valve, interconnecting the first and second terminals on
the first side of said fourth valve, the first and second terminals
of the second side of said fourth valve connected to said
container.
18. A low-loss supply system for filling a container for liquified
gas as claimed in claim 17 wherein said liquified gas is liquified
oxygen.
19. A low-loss supply system for filling a container for liquified
gas as claimed in claim 17 wherein said supply tank and said
intermediate tank are cryogenic storage vessels and wherein said
first, second, third and fourth pipelines are insulated
pipelines.
20. The structure of claim 13 including condensing loop means for
condensing vapors from at least one of said tanks.
21. The structure of claim 20 wherein said loop means is located so
that condensed vapors are returned to the liquid phase of one of
said tanks.
22. The structure of claim 20 wherein said loop means is located
inside of one of said tanks.
23. The structure of claim 13 including:
a source of condensing fluid;
a condenser; and
means for directing said condensing fluid to said condenser located
so that vapors from at least one of said tanks is brought into
contact therewith and causes said vapors to condense.
24. The structure of claim 23 wherein said condenser is located so
that condensed vapors are returned to the liquid phase of one of
said tanks.
25. The structure of claim 23 wherein said condenser is located
inside of one of said tanks.
26. The structure of claim 13 wherein said second interconnecting
means includes a pipeline for connecting the vapor phase of said
container to the vapor phase of said intermediate tank.
27. The structure of claim 26 including a one-way valve in said
pipeline for preventing the flow of gas in said pipeline in a
direction out of said intermediate tank.
28. The structure of claim 26 including:
a source of condensing fluid; a condenser, and,
means for directing said condensing fluid to said condenser located
so that vapors from at least one of said tanks is brought into
contact therewith and causes said vapors to condense.
29. The structure of claim 28 wherein said condenser is located so
that condensed vapors are returned to the liquid phase of one of
said tanks.
30. The structure of claim 29 wherein said condenser is located
inside of one of said tanks. .Iadd. 31. A low-loss method of
filling a container for liquified gas from a supply system
comprising the steps of:
transferring liquid from a first vessel into a second vessel, and
transferring vapor from said second vessel to said first vessel
whereby the pressure between said first and second vessels remains
equalized as said liquid is transferred;
isolating said first vessel from said second vessel;
connecting said second vessel and said container for liquified gas
to equalize the pressure between said second vessel and said
container for liquified gas;
connecting said first vessel to said container for liquified gas to
permit vapor to flow therebetween;
vapor thereby being permitted to flow from said container for
liquified gas into said first vessel and liquid thereby being
permitted to flow from said second vessel into said container for
liquified gas..Iaddend..Iadd. 32. The method of claim 31 including
the step of permitting the pressure of said second vessel to become
higher than the pressure of said container for liquified gas.
.Iaddend. .Iadd. 33. A pump-free low-loss supply system for filling
a container for liquified gas comprising:
a supply tank for housing said liquified gas;
an intermediate tank for temporarily storing said liquified
gas;
first interconnecting means for interconnecting said intermediate
tank to said supply tank for allowing liquid to flow by gravity
from said supply tank to said intermediate tank and vapor to flow
from said intermediate tank to said supply tank; and
second interconnecting means for interconnecting said intermediate
tank and supply tank to said container so as to allow liquid from
said intermediate tank to flow into said container and vapor from
said container for liquified gas to flow into said supply tank,
said liquid thereby being transferred pump-free from said supply
tank to said container. .Iaddend..Iadd. 34. The system of claim 33
including means for raising the pressure of said intermediate tank
above the pressure of said container for liquified gas. .Iaddend.
Description
This invention relates to a method and apparatus for filling small
containers from large containers and more particularly to a method
and apparatus for filling a small container with liquified gas from
a large container, without the loss of gas vapor.
It is often necessary to transfer liquified gases from larger
containers to smaller containers. For example, oxygen converters
used for converting liquified oxygen (LOX) to a gas for use by the
crews of high altitude aircraft are usually filled from larger
tanks; and, in this regard, objects of this invention are to
provide a new and improved method and apparatus for transferring a
liquified gas from one container to another.
Many of the transferred gases are quite volatile and tend to boil
off rapidly during conventional transfer methods. Hence, because
many of these gases are also quite expensive to produce, it is
another object of this invention to provide a particularly low-loss
method of transferring a liquified gas from a large container to a
small container.
Some liquified gas vapors that are released during conventional
transfer methods are highly dangerous because they readily support
combustion. In addition, flammable gases such as hydrogen and
natural gas often must be transferred from large containers to
small containers for use at particular locations. If gas vapors are
released during the transfer of flammable gases, they produce a
highly dangerous environment because of both combustability and
possibly inhalation. Consequently, it is another object of the
invention to provide a safer method and apparatus for performing
the desired transfer without vapor of the transferred gas boiling
off into the atmosphere.
It is still a further object of this invention to provide a new
method and apparatus for transferring cryogenic fluids in a manner
which does not require expensive cryogenic pumps so as to further
reduce boil off losses.
SUMMARY OF THE INVENTION
In accordance with principles of this invention, the liquified gas
is first transferred from a supply tank to an intermediate tank by
gravity flow. After a predetermined amount of the liquified gas has
been transferred in this manner, pressure is equalized between the
intermediate tank and the container to be filled. Thereafter,
pressure from the container is bled down into the supply tank
causing liquified gas to flow from the intermediate tank into the
container. Transfer is ended after the container has received a
desired amount of liquified gas. Thereafter, pressure is equalized
between the supply and intermediate tanks, and the cycle is
repeated to fill a second container.
In accordance with other principles of this invention, the supply
container and the intermediate container are vacuum insulated, as
are the lines interconnecting the supply tank, the intermediate
tank and the converter so as to further conserve gas by preventing
boil-off loss.
It will be appreciated from the foregoing summary that the
invention provides an uncomplicated method and equally
uncomplicated apparatus for transferring a liquid gas from a supply
container or tank to a smaller container or converter with low
vapor loss. By utilizing the pressures in the tanks and gravity to
cause the liquified gas to flow, the need for an expensive
cryogenic pump is eliminated. In addition, the high boil-off
associated with the use of cryogenic pumps is also eliminated.
While the illustrated use of the herein described invention is to
transfer LOX from a supply container to a converter, and thus
reduce the vapor danger associated with such transfers, it will be
appreciated that the invention can be utilized to transfer other
types of liquified gases. For example, the invention can be
utilized to transfer flammable liquified gases, such as hydrogen
and natural gas.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing objects and many of the attendant advantages of this
invention will become more readily appreciated as the same become
better understood when taken in conjunction with the accompanying
drawings, wherein:
FIG. 1 is a schematic diagram illustrating a preferred embodiment
of the invention;
FIGS. 2, 3, and 4 are schematic diagrams illustrating the sequence
of transfer between the supply container and the container to be
filled;
FIG. 5 is a schematic diagram of a condensing system for use with
the embodiments of the invention illustrated in FIGS. 1 and 6;
and,
FIG. 6 is a schematic diagram illustrating an alternate embodiment
of a portion of the structure illustrated In FIG. 1.
DESCRIPTION OF A PREFERRED EMBODIMENT
FIG. 1 illustrates a preferred embodiment of the invention and
comprises: a supply tank 11; an intermediate tank 13; a converter
15; four primary valves 17, 18, 19 and 21; four secondary valves
23, 25, 27 and 29; an automatic valve 31; two pressure relief
valves 33 and 35; a rupture disc 37; and, three pressure indicators
designated P1, P2 and P3.
The supply tank has a liquid input/output line 39 and a vapor
input/output line 41; the intermediate tank 13 which is of the
saddle-type has a liquid input/output line 43 and a vapor
input/output line 45; and, the converter has a liquid input/output
line 47 and a vapor input/output line 49. The liquid input/output
line 39 of the supply tank is connected by pipes through the first
secondary valve 23 and a filter 51 to an input connection. The
input connection allows liquified oxygen (or another liquified gas,
as the case may be) to be inserted into the supply tank 11 to fill
that tank. The liquid input/output line 39 of the supply tank 11 is
also connected by pipes through the first primary valve 17 and a
first supply saddle coupling member 53 to the liquid input/output
line 43 of the saddle tank 13. The vapor input/output line 45 of
the saddle tank 13 is connected by pipes through a second
supply/saddle coupling member 55 and the second primary vale 18 to
the vapor input/output line 41 of the supply tank 11.
A pressure sensor 57, located in the saddle tank, is connected by
pipes through a heat exchanger coil 58, a pressure regulating valve
59, and the second secondary valve 25 to the pipe line connecting
the vapor input/output lines of the saddle and supply tanks 11 and
13. The same pipe line is also connected to P2 and through the
first pressure relief valve 33 to a vent output. The vapor
input/output line 41 of the supply tank 11 is also connected by a
pipe through the third secondary valve 27 to the vent output,
through the second pressure relief valve 35 to the vent output and
through the rupture disc 37 to the vent output. In addition, the
vapor input/output line 41 of the supply tank 11 is connected to
P1. The liquid input/output line 39 of the supply tank 11 is
connected by a pipe through the fourth secondary valve 29 and a
heat exchanger coil 61 to the vapor input/output line 41 of the
supply tank 11.
The liquid input/output line 43 of the saddle tank 13 is connected
by pipes through a saddle-converter coupling member 63 to a first
terminal on one side of the automatic valve 31. The liquid
input/output line of the supply tank 39 is connected by pipes
through the third primary valve 19 and a supply/converter coupling
element 65 to a second terminal on the same side of the automatic
valve 31. The fourth primary valve 21 is in a pipe connected across
the first and second terminals on this same side of the automatic
valve 31. In addition, P3 is connected to the pipe line that
connects the liquid input/output line 39 of the supply tank 11 to
the automatic valve 31. The other side of the automatic valve 31 is
connected by pipes to the liquid and vapor input/output lines 47
and 49 of the converter 15.
All of the pipe lines connecting the supply tank to the saddle tank
and connecting the supply and saddle tanks to the converter are
vacuum insulated to prevent undesirable boil-off. The remaining
lines are not illustrated as being insulated, however, they may be
insulated, if desired. The insulated lines connecting the supply
tank and the saddle tank and the converter form the primary
apparatus of the invention and are utilized to carry out the method
as hereinafter described with respect to FIGS. 2, 3 and 4. The
remaining lines provide a means for filling the supply tank as well
as for venting the various vapor lines and tanks as necessary to
the normal operation of a liquified gas system, as will be
understood by those skilled in the art. For example, the first
pressure relief valve 33 provides pressure relief for the saddle
tank. Similarly, the second pressure relief valve 35 provides
pressure relief for the supply tank. The heat exchanger coil 58 and
61 allows vaporization of the liquid to build pressure in their
respective saddle and supply tanks, when desired.
Turning now to a description of the operation of the apparatus
illustrated in FIG. 1 for carrying out the method of the invention;
it is initially assumed that the pressure in both the supply tank
and the saddle tank is zero psig. In addition, it is assumed that
the pressure in the converter tank is in the range of 50-100 psig.
Similarly, it is assumed that the temperature of the converter is
substantially at liquified oxygen temperature. Moreover, in
accordance with the principles of the invention, the saddle tank is
at a lower elevation than the supply tank.
The first step of the method of the invention is the opening of the
first and second primary valves 17 and 18 (FIG. 2). When this
occurs, the liquid flows by gravity from the supply tank 11 through
the first valve 17 into the saddle tank and vapor flows from the
saddle tank through the second valve 18 into the supply tank. When
the desired amount of liquid has flowed from the supply tank to the
saddle tank, the first and second primary valves 17 and 18 are
closed. This liquid-vapor flow increases pressure slightly in both
tanks to about 3-5 psig, for example.
Next the converter 15 is coupled to the system and the automatic
valve 31 and the fourth primary valve 21 are opened. In accordance
with this step of the method (FIG. 3), pressure is equalized
between the converter and the saddle tank through the
saddle/converter coupling element 63. When the pressure in these
two tanks has equalized, they will both be at a value of, for
example, 30 psig, depending upon the size of the tanks.
In accordance with the method of the invention, after equalization
between the converter and the saddle tank has been completed, the
fourth primary valve 21 is closed and the third primary valve 19 is
opened (FIG. 4). When the third primary valve is opened and the
fourth primary valve is closed, the pressure differential between
the converter 15 and the supply tank 11 causes vapor to flow from
the converter 15 to the supply tank 11. This action causes liquid
to flow from the saddle tank 13 into the converter 15. Any vapor
produced by this liquid flow passes into the supply tank 11 and
bubbles through the liquid phase in the supply tank to cause
turbulence in the supply tank which reduces thermal stratification
and undue pressure rise in the supply tank. To prevent reverse
vapor flow from the converter 15 to the saddle tank 13 a one-way
valve 67 is included in the automatic valve 31.
When the converter has filled to a satisfactory level, the third
primary valve 19 is closed. In addition, the automatic valve 31 is
closed and the converter is disconnected. The second primary valve
18 is then opened to bring the pressure in the saddle tank down to
the pressure in the supply tank. Because of the accumulation of
vapor in these insulated tanks, the pressure in the tanks will
rise, up to 20 psig, for example.
When it is desired to fill another converter from the supply tank,
the foregoing cycle is repeated. However, in this case, the supply
tank starts at an initial pressure of about 20 psig. Hence, at the
end of the filling of the second converter, the pressure in the
supply and saddle tanks will be about 40 psig, for this example.
Consequently, ultimately, it will become necessary to reduce the
pressure in the supply and saddle tanks.
Pressure in the supply tank 11 and intermediate tank 13 is,
preferably, reduced by either of two methods. In accordance with
the first method, these tanks are removed to a remote area and bled
down by allowing the oxygen vapor to be vented into the atmosphere.
In accordance with the second method, the tanks may be provided
with condensing loops 70 and 71 in FIG. 5 for circulating liquified
nitrogen from a nitrogen supply tank 72.
In the above regard, liquified nitrogen from the condensing fluid
tank 72 is directed by means of suitable valving, not shown,
through insulated lines 74 and 75 into the loops 70 and 71 where
the tank vapors are condensed in the tanks themselves. The nitrogen
vapors are then vented to the atmosphere as illustrated in the FIG.
5 schematic. In this manner the pressures in the supply and saddle
tanks are not only reduced to substantially zero but the tank
vapors are condensed and recovered without the possible danger of
their being released into the atmosphere.
When the method of the invention is used with the above described
structure vapor from the converter 15 flows out of end 78 of line
43 after the converter is coupled to the system and valves 21 and
31 are opened. Hence, the vapor from 78 flows upwardly through the
saddle tank's liquid to cause turbulence which, in many cases is
undesirable. Note in this regard, that the intermediate tank 13 is
not a long term "storage" tank and, therefore, does not have the
thermal stratification problems of the supply tank 11.
Consequently, although it can be advantageous for vapor to bubble
through the liquid phase of the supply tank, this is not generally
the case with the intermediate tank.
The FIG. 6 structure eliminates both the bubbling of vapor from the
converter 15 through the saddle tank's liquid phase and eliminates
the need for the FIG. 1 embodiment's valve 21. In this regard, the
FIG. 6 embodiment includes a vacuum insulated line 80 extending
between point 82 on the supply tank's link 39 and point 84 at the
top of the saddle-type intermediate tank 13. The line 80 includes a
one-way check valve 86 for permitting vapor to flow only in the
direction of the arrow (toward point 84); and does not include
either a valve such as 21 or a line extending between the
converter's liquid-input and vapor-output lines. The remainder of
the FIG. 6 embodiment is the same as FIG. 1 and will not be further
described.
The operation of the FIG. 6 embodiment is similar to that of FIG.
1. In this regard, liquid is first transferred from the supply tank
to the intermediate tank and the pressure therebetween is equalized
before the supply and saddle tanks are isolated. Next, the
converter is coupled to the system at coupling elements 63 and 65;
and vapor from converter 15 flows into the top of the saddle tank
13 through line 80 and the check valve 86. When the pressure in
these tanks in thusly equalized, valve 19 is opened to permit vapor
from converter 15 to flow into the supply tank 11 in the same
manner as was described in connection with the first embodiment.
Similarly, as the pressure in the converter drops, fluid from the
saddle tank is forced through line 43 and check valve 67 into the
converter. It should be noted that the check valve 86 prevents the
vapor from the saddle tank from flowing at this time into either
the supply tank or the converter. In other respects, operation of
the two embodiments is the same.
It will be appreciated from the foregoing description that the
invention comprises a method and apparatus for filling a small
container or converter from a large container or supply tank. In
general, the method comprises the steps of: equalizing the pressure
between first and second vessels in the supply system; transferring
liquid from the first vessel to the second vessel and transferring
vapor from the second vessel to the first vessel; isolating the
first vessel from the second vessel; equalizing the pressure
between the second vessel and the container for receiving the
liquified gas; isolating the vapor phase of the second vessel from
the vapor phase of the container for liquified gas; connecting the
first vessel to the container; connecting the second vessel to the
container for liquified gas so that liquid from said second vessel
flows into said container while vapor from the container flows into
the first vessel; and, isolating the container from said first and
second vessels. It will be appreciated that this method has certain
advantages in that it eliminates the necessity for pumping the
liquified gas from one vessel to a second vessel. In addition it
eliminates some of the other inherent disadvantages of former such
systems. Moreover, because constant interconnections are provided,
vapor loss is greatly reduced over prior art container filling
systems; and the method also has the advantage of reducing
stratification in the supply tank.
In addition to being an uncomplicated method, the invention also
provides for safe recovery of the supply tank vapors; and provides
uncomplicated apparatus for carrying out the method in that only a
small quantity of interconnecting lines and valves are utilized to
carry out the method of the invention.
While a preferred embodiment of the invention has been illustrated
and described, it will be appreciated by those skilled in the art
and others that various changes can be made therein without
departing from the spirit and scope of the invention.
For example, although the vapor condensation step has been
described in terms of both supply tank 11 and saddle tank 13, it
will be apparent that were the vapor phases of the two tanks are
connected together as by valve 18, the condensation step can take
place by connection of either tank into one of the loops 70.
* * * * *