The present invention is a method and apparatus for gelling liquid propane and other liquefied gasses. The apparatus includes a temperature controlled churn mixer, vacuum pump, liquefied gas transfer tank, and means for measuring amount of material entering the mixer. The method uses gelling agents such as silicon dioxide, clay, carbon, or organic or inorganic polymers, as well as dopants such as titanium, aluminum, and boron powders. The apparatus and method are particularly useful for the production of high quality rocket fuels and propellants

DiSalvo, Roberto

Elliott, Adam

Kosier, Ryan

Shepherd, Phillip

NASA Technical Reports Server

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4
(12) United States Patent
Elliott et al.
(54) APPARATUS AND METHOD FOR GELLING
LIQUEFIED GASSES
(75) Inventors: Adam Elliott, Scotsborro, AL (US);
Roberto DiSalvo, Madison, AL (US);
Phillip Shepherd, Fort Payne, AL (US);
Ryan Kosier, Huntsville, AL (US)
(73) Assignee: CFD Research Corporation,
Huntsville, AL (US)
(*) Notice: Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 999 days.
(21) Appl. No.: 11/584,954
(22) Filed:	 Oct. 23, 2006
(65)	 Prior Publication Data
US 2007/0245750 Al	 Oct. 25, 2007
Related U.S. Application Data
(63) Continuation-in-part of application No. 11/292,442,
filed on Dec. 2, 2005.
(51) Int. Cl.
B01F 11/00	 (2006.01)
(52) U.S. Cl . ....................... 366/256; 366/241; 366/242;
366/255
(lo) Patent No.:	 US 7,810,990 B2
(45) Date of Patent:	 Oct. 12 9 2010
(58) Field of Classification Search ................ 48/127.3;
62/54.1, 66, 68; 149/108.8; 336/241-335
See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
5,288,915 A *	 2/1994 Walters ...................... 568/323
2002/0196704 Al * 12/2002 May ........................... 366/256
2003/0159811 Al *	 8/2003 Nurmi ........................ 165/132
2005/0158477 Al *	 7/2005 Vezin et al . .............. 427/430.1
* cited by examiner
Primary Examiner Jerry Lorengo
Assistant Examiner Jared Wood
(74) Attorney, Agent, or Firm Tomas Friend, LLC
(57) ABSTRACT
The present invention is a method and apparatus for gelling
liquid propane and other liquefied gasses. The apparatus
includes a temperature controlled churn mixer, vacuum
pump, liquefied gas transfer tank, and means for measuring
amount of material entering the mixer. The method uses gel-
ling agents such as silicon dioxide, clay, carbon, or organic or
inorganic polymers, as well as dopants such as titanium,
aluminum, and boron powders. The apparatus and method are
particularly useful for the production of high quality rocket
fuels and propellants.
13 Claims, 2 Drawing Sheets
6?
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FIG. 1
1^1)
U.S. Patent	 Oct. 12 9 2010	 Sheet 1 of 2	 US 7,810,990 B2
515
45
U.S. Patent	 Oct. 12 9 2010	 Sheet 2 of 2	 US 7,810,990 B2
FIG. 2
US 7,810,990 B2
1
APPARATUS AND METHOD FOR GELLING
LIQUEFIED GASSES
CROSS-REFERENCE TO RELATED
APPLICATIONS
This Application in a Continuation in Part of application
Ser. No. 11/292,442, filed 2 Dec. 2005, whichis incorporated
by reference in its entirety.
STATEMENT REGARDING FEDERALLY
SPONSORED RESEARCH OR DEVELOPMENT
The U.S. Government may have certain rights in this inven-
tionpursuant to SBIR Contract No. NNM05AA56C awarded
by NASA.
INCORPORATED-BY-REFERENCE OF
MATERIAL ON A CD
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods and apparatuses
for gelling liquefied gasses such as liquidpropane (LP), liquid
methane (LCH4), liquidmixed oxides of nitrogen, (MON-X),
or cryogenic liquids such as liquid oxygen (LOX). The appa-
ratus includes a churn mixer specially adapted for liquefied
gasses and the associated method produces gelled rocket
propellants and other useful gelled liquefied gasses.
2. Description of Related Art
Methods and apparatus for gelling rocket fuels are known
in the art. Methods of gelling liquefied gasses and cryogenic
liquids can be found in the following patents, which are
incorporated by reference. U.S. Pat. No. 4,011,730 discloses
crystals of ice or methyl alcohol as gelling agents to gel
liquefied natural gas in order to improve transportation effi-
ciency by displacing inert gasses normally dissolved in the
fuel. U.S. Pat. No. 4,295,346 discloses a system for gelling
cryogenic liquids, including rocket fuels, using crystallized
vapor droplets as gellant. U.S. Pat. No. 4,305,256 describes a
process for making methane cryogenic liquid gels by forming
a mixture of cryogen vapor and droplets and combining the
mixture with a gelling agent that is a liquid or gas at ambient
temperature but a solid at cryogenic temperatures. U.S. Pat.
No. 5,705,771 provides a cryogenic rocket propellant com-
prising a slurry of solid methane in liquid hydrogen.
The preceding inventions are directed to the large-scale
preparation of gelled liquefied gasses or cryogenic liquids.
Small rocket motors, such as those used to provide attitude
control require fuels of high quality and reliability and in
smaller amounts than booster rockets, and other large rocket
motors. Apparatus and methods are needed for the production
of high quality gelled liquefied gasses with uniform distribu-
tion of gellant and particulate dopants and desirable rheologi-
cal properties. The present invention provides apparatus and
methods to satisfy this need and has been demonstrated for
the production of gelled liquid propane (GLP) and mixed
oxides of nitrogen (MON), including 70% N204+30% NO(MON-30). The products are of high quality and made in
amounts suitable for rocket motors such as those found in
divert and attitude control systems.
BRIEF SUMMARY OF THE INVENTION
The present invention is an apparatus and method for pro-
ducing gelled liquefied gasses, including, for example, GLP
2
and MON-30. The apparatus and method are particularly
well-suited for making gelled propellants for high-perfor-
mance upper stage and Divert and Attitude Control Systems,
but can also be used for the production of gelled liquefied
5 gasses for other purposes such as propellants for automobile
airbag inflators, emergency escape systems for aircraft,
underwater propulsion, and fuel cell fuels. The apparatus and
method produce gels in which gellants, such as silicon diox-
ide, clay, carbon, or organic polymers such as hydroxypropyl
10 cellulose, inorganic polymers and additives, such as powders
of boron, carbon, lithium, aluminum, and/or titanium are
homogeneously dispersed in the final product. The use of
additives produces doped gels with improved function such
as hypergolicity, higher specific impulse (Isp), density
impulse, and desired theological properties.
15
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cut away view of a temperature controlled
churn mixer.
20	 FIG. 2 is a diagram showing components of the gelling
method.
DETAILED DESCRIPTION OF THE INVENTION
25
Gelling Apparatus
In the example provided, LP is gelled using a one-liter,
temperature controlled churn-mixer (FIG. 1). The mixer com-
prises a cylindrical vessel 10 with a heat exchange coil 12
30 located in the side and bottom walls of the ves sel. The exterior
surfaces of vessel 10 are thermally insulated with high density
foam, polystyrene foam, or other high R value insulator (not
shown). The heat exchange coil in this case comprises copper
tubing in liquid communication with a cooling pump that
35 circulates cooling liquid such as chilled ethylene glycol, etha-
nol, acetone, or freon to control temperature inside the mixer.
The vessel volume 14 is set by positioning a piston-like clo-
sure lid, or follower plate, 20 at a set distance from the bottom
of the vessel and securing it in place by compression of
o-rings 24. Follower plate 20, comprises a heat exchange coil
40 22 or a void volume for circulating a cooling liquid. This
arrangement provides temperature control on all surfaces in
contact with vessel lumen volume 14. A rod 30, attached
externally to a pneumatic actuator, goes through the center of
the closure-lid and attaches to a perforated churn-plate 40. In
45 this example, the churn-plate has thirty-six, 6 mm diameter
holes and is pneumatically cycled up and down, through the
entire mixer volume. Ports 50 and 60 are for connection to a
liquefied gas transfer tank and vacuum pump, respectively.
The ability to evacuate the mixing chamber before the intro-
50 duction of liquefied gas prevents the formation of bubbles
during the mixing process. A third port 70 is located at the
bottom of the mixer for removing GLP or other gelled product
from the mixer and can also be used to in some embodiments
as a port for filling the chamber in a manner similar to filling
a syringe. Pneumatically actuated zero void volume valves
55 52, 62, and 72 are used to regulate flow through ports 50, 60,
and 70, respectively. Two thermocouples 80 and two pressure
sensors, not shown, are used to monitor temperature and
pressure inside the vessel.
The churn mixer may be scaled up or down to 500 liters,
60 200 liters, 50 liters, 10 liters, or 0.5 liters, for example. The
mixing vessel components may be made of any material
resistant to the chemicals, temperatures and pressures used in
the gelling process. In the present example, the mixer and
transfer tank are made of aluminum. Other materials such as
65 stainless steel may and borosilicate glass may also be used.
Pneumatically actuated zero void volume valves are preferred
but other types of valves may be used.
US 7,810,990 B2
3
EXAMPLE I
Gelling Liquid Propane
A schematic of the components used in the gelling method
is shown in FIG. 2 and comprises an aluminum storage tank 5
located on scale 15, vacuum pump 25, churn mixer vessel 10,
connecting lines 35, cooling bath 45 for circulating ethanol
chilled with dry ice, and valves 52, 62, 72, and 82. The outer
surfaces of mixer vessel 10 and the follower plate (not shown)
are insulated with a removable, high-density foam insulating
material. Connecting lines 35 are flexible, stainless steel
braided lines coated with Teflon®.
20 grams of Cabot M-58 fumed silica were placed in
mixing vessel 10. The follower plate was lowered into the
mixing vessel until the churn plate contacted the gellant. The
vessel was sealed by compressing o-rings in the flower plate.
Transfer tank 5 and mixing vessel 10 were evacuated using
vacuum pump 25 with valve 72 closed and valves 52, 62, and
82 open. Valves 52, 62, and 82 were then closed and LP was
transferred from an LP tank (not shown) into the evacuated
transfer tank through a fill valve (not shown). Scale 15 was
used to monitor the mass of the propane in the aluminum tank
during transfer. The fill valve was then closed.
The temperature inside the transfer tank and mixing vessel
was lowered to —45° C. to prepare the propane gel mixer for
propane transfer. The mixer was cooled after vacuum was
reached in order to prevent condensation inside the mixer.
Valve 82 was slowly opened to fill connecting line 35 between
the transfer tank and the mixer. The mass of LP lost from the
transfer tank to the transfer line was recorded. Valve 52 was
slowly opened to allow LP from transfer tank 5 into mixing
vessel 10. The follower plate was pulled upward by a pneu-
matic actuator to draw liquid propane into the mixing vessel
until 500 grams of propane was transferred into the mixer and
valve 52 was closed. LP and gellant were mixed with a chum
plate frequency of I Hz for 2 minutes. Valve 72 was opened
and GLP was pressed from the mixer into a storage container
by moving the follower plate to the bottom of the mixing
vessel.
EXAMPLE 2
Gelling MON-30
The apparatus used is the same as for gelling liquid propane
with the exception that the o-rings (24 in FIG. 1) were made
of the MON-resistant material Kalrez(k. Storage tank 5 was
filled with MON-30 from a holding tank rather than LP and
the temperature in the mixer was maintained between —I' C.
and —8° C.
It is possible to gel liquefied gasses having lower boiling
points and higher vapor pressures than LP as long as the
combination of temperature and pressure in the mixing cham-
ber maintain the liquefied gas in the liquid state. Extremely
low temperatures can be achieved by using liquid nitrogen or
liquid helium as the circulating fluid for heat exchange.
The above examples are presented for illustrative purposes
to describe the present apparatus and method. Although par-
ticular embodiments of the present invention have been
described, it is not intended that such references be construed
as limitations upon the scope of this invention except as set
forth in the following claims.
What is claimed is:
1. An apparatus for gelling a liquefied gas comprising a
churn mixer comprising:
a) a cylindrical mixing vessel open at one end, sealed at the
other end, and comprising a means of circulating heat
exchange fluid in the walls of the vessel,
4
b) a closure lid that fits inside the open end of the mixing
vessel, said closure lid comprising o-rings configured to
seal the mixing vessel upon compression of said o-rings,
an opening, and means for circulating a heat exchange
5	 fluid within the closure lid,
c) a rod passing through the opening in the closure lid, said
rod attached to a perforated plate located inside the
mixing vessel and mechanically coupled to a means for
moving the perforated plate back and forth between the
10 ends of the mixing vessel, said perforated plate being
oriented parallel to the ends of the cylindrical mixing
vessel,
d) a first valved port in the mixing vessel or closure lid
configured to deliver liquefied gas into and optionally
configured to remove gelled liquefied gas from the mix-
15	 ing vessel,
e) a second valved port in the mixing vessel or closure lid
configured to evacuate the mixing vessel and connected
to a means for producing a vacuum, and
f) a supply of heat exchange fluid in fluid communication
20 with said means of circulating heat exchange fluid in the
walls of the vessel and said means for circulating a heat
exchange fluid within the closure lid, said supply of
chilled heat exchange fluid configured to maintain said
heat exchange fluid at a temperature of 0° C. or lower,
25	 wherein exterior surfaces of the mixing vessel are covered
with a thermally insulating material.
2. The apparatus of claim 1, further comprising a transfer
tank containing a liquefied gas to be gelled in liquid commu-
nication with the first valved port.
30 3. The apparatus of claim 2, wherein the transfer tank rests
on a scale configured to measure the mass of liquefied gas
transferred into and from the transfer tank.
4. The apparatus of claim 1, wherein the means for moving
the perforated plate is a pneumatic drive configured to move
35 the perforated plate through the entire mixer volume.
5. The apparatus of claim 1, wherein the perforated plate
consists of a metal plate containing holes with diameters of
between 4 and 8 mm.
6. The apparatus of claim 1, wherein the volume of the
40 mixing vessel is between 0.1 liters and 500 liters.
7. The apparatus of claim 1, and further comprising a third
valved port configured to remove gelled liquefied gas from
the mixing vessel.
8. The apparatus of claim 7, wherein the closure lid is
45 mechanically coupled to a means for moving said closure lid
and the closure lid is configured to serve as a piston config-
ured to push contents of the mixing vessel out and to draw
materials into the mixing vessel through the third port.
9. The apparatus of claim 7, wherein the first and second
50 valved ports are located in the closure lid and the third valved
port is located in a wall of the mixing vessel opposite the
closure lid.
10. The apparatus of claim 1, wherein the heat exchange
fluid is a chilled cooling fluid selected from the group con-
55 sisting of ethylene glycol, ethanol, acetone, and freon.
11. The apparatus of claim 1, wherein the first and second
valved ports comprise pneumatically actuated zero void vol-
ume valves.
12. The apparatus of claim 1, and further comprising a
60 thermocouple in the mixing vessel or closure lid configured to
measure the temperature inside the mixing vessel.
13. The apparatus of claim 1, wherein the liquefied gas is
liquidpropane and the supply of chilled heat exchange fluid is
configured to maintain said heat exchange fluid at a tempera-
65 ture of —45° C.


Apparatus and method for gelling liquefied gasses

A method and apparatus for gelling liquid propane and other liquefied gasses includes a temperature controlled churn mixer, vacuum pump, liquefied gas transfer tank, and means for measuring amount of material entering the mixer. The apparatus and method are particularly useful for the production of high quality rocket fuels and propellants

10
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(12) United States Patent
Elliott et al.
(54) APPARATUS AND METHOD FOR GELLING
LIQUEFIED GASSES
(75) Inventors: Adam Elliott, Hollywood, AL (US);
Roberto DiSalvo, Madison, AL (US);
Phillip Shepherd, Hollywood, AL (US);
Ryan Kosier, Athens, AL (US)
(73) Assignee: CFD Research Corporation,
Huntsville, AL (US)
(*) Notice: Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 0 days.
(21) Appl. No.: 12/874,242
(22) Filed:	 Sep. 2, 2010
(65)	 Prior Publication Data
US 2010/0319822 Al	 Dec. 23, 2010
Related U.S. Application Data
(62) Division of application No. 11/584,954, filed on Oct.
23, 2006, now Pat. No. 7,810,990.
(51) Int. Cl.
BOIF 3112	 (2006.01)
BOIJ13/00	 (2006.01)
(lo) Patent No.:	 US 8,047,703 B2
(45) Date of Patent:	 Nov. 1, 2011
(52) U.S. Cl. ........ 366/256; 366/139; 366/149; 366/241;
366/242; 366/255; 516/98; 516/99; 516/110;
516/111
(58) Field of Classification Search ...... 149/1; 366/139,
366/149, 241, 242, 255, 256; 516/98, 99,
516/110,111
See application file for complete search history.
(56) References Cited
U.S. PATENT DOCUMENTS
2002/0196704 Al * 12/2002 May .............................. 366/256
2005/0158477 Al * 	 7/2005 Vezin et al . ................ 427/430.1
* cited by examiner
Primary Examiner Jerry A Lorengo
Assistant Examiner Jared Wood
(74) Attorney, Agent, or Firm Tomas Friend
(57) ABSTRACT
A method and apparatus for gelling liquid propane and other
liquefied gasses includes a temperature controlled churn
mixer, vacuum pump, liquefied gas transfer tank, and means
for measuring amount of material entering the mixer. The
apparatus and method are particularly useful for the produc-
tion of high quality rocket fuels and propellants.
9 Claims, 2 Drawing Sheets
r')
https://ntrs.nasa.gov/search.jsp?R=20110023491 2019-08-30T18:12:25+00:00Z
'.2
10
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FIG. 1
Q?
U.S. Patent	 Nov. 1, 2011	 Sheet 1 of 2	 US 8,047,703 B2
15
45
U.S. Patent	 Nov. 1, 2011	 Sheet 2 of 2	 US 8,047,703 B2
FIG. 2
US 8,047,703 B2
1
APPARATUS AND METHOD FOR GELLING
LIQUEFIED GASSES
CROSS-REFERENCE TO RELATED
APPLICATIONS
This Application is a Divisional of and claims priority
under 35 U.S.C. 120 to U.S. application Ser. No. 11/584,954,
filed 23 Oct. 2006.
FEDERALLY SPONSORED RESEARCH OR
DEVELOPMENT
2
but can also be used for the production of gelled liquefied
gasses for other purposes such as propellants for automobile
airbag inflators, emergency escape systems for aircraft,
underwater propulsion, and fuel cell fuels. The apparatus and
5 method produce gels in which gellants, such as silicon diox-
ide, clay, carbon, or organic polymers such as hydroxypropyl
cellulose, inorganic polymers and additives, such as powders
of boron, carbon, lithium, aluminum, and/or titanium are
homogeneously dispersed in the final product. The use of
io additives produces doped gels with improved function such
as hypergolicity, higher specific impulse (Isp), density
impulse, and desired theological properties.
The U.S. Government may have certain rights in this inven-	 BRIEF DESCRIPTION OF THE DRAWINGS
tion pursuant to SBIR Contract No. NNM05AA56C awarded 15
by NASA.	 FIG. 1 shows a cut away view of a temperature controlled
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods and apparatuses
for gelling liquefied gasses such as liquidpropane (LP), liquid
methane (LCH4), liquidmixed oxides of nitrogen, (MON-X),
or cryogenic liquids such as liquid oxygen (LOX). The appa-
ratus includes a churn mixer specially adapted for liquefied
gasses and the associated method produces gelled rocket
propellants and other useful gelled liquefied gasses.
2. Description of Related Art
Methods and apparatus for gelling rocket fuels are known
in the art. Methods of gelling liquefied gasses and cryogenic
liquids can be found in the following patents, which are
incorporated by reference. U.S. Pat. No. 4,011,730 discloses
crystals of ice or methyl alcohol as gelling agents to gel
liquefied natural gas in order to improve transportation effi-
ciency by displacing inert gasses normally dissolved in the
fuel. U.S. Pat. No. 4,295,346 discloses a system for gelling
cryogenic liquids, including rocket fuels, using crystallized
vapor droplets as gellant. U.S. Pat. No. 4,305,256 describes a
process for making methane cryogenic liquid gels by forming
a mixture of cryogen vapor and droplets and combining the
mixture with a gelling agent that is a liquid or gas at ambient
temperature but a solid at cryogenic temperatures. U.S. Pat.
No. 5,705,771 provides a cryogenic rocket propellant com-
prising a slurry of solid methane in liquid hydrogen.
The preceding inventions are directed to the large-scale
preparation of gelled liquefied gasses or cryogenic liquids.
Small rocket motors, such as those used to provide attitude
control require fuels of high quality and reliability and in
smaller amounts than booster rockets, and other large rocket
motors. Apparatus and methods are needed for the production
of high quality gelled liquefied gasses with uniform distribu-
tion of gellant and particulate dopants and desirable rheologi-
cal properties. The present invention provides apparatus and
methods to satisfy this need and has been demonstrated for
the production of gelled liquid propane (GLP) and mixed
oxides of nitrogen (MON), including 70% N204+30% NO
(MON-30). The products are of high quality and made in
amounts suitable for rocket motors such as those found in
divert and attitude control systems.
BRIEF SUMMARY OF THE INVENTION
The present invention is an apparatus and method for pro-
ducing gelled liquefied gasses, including, for example, GLP
and MON-30. The apparatus and method are particularly
well-suited for making gelled propellants for high-perfor-
mance upper stage and Divert and Attitude Control Systems,
churn mixer.
FIG. 2 is a diagram showing components of the gelling
20 method.
DETAILED DESCRIPTION OF THE INVENTION
In the example provided, LP is gelled using a one-liter,
25 temperature controlled chum-mixer (FIG.1). The mixer com-
prises a cylindrical vessel 10 with a heat exchange coil 12
located in the side and bottom walls of the vessel. The exterior
surfaces of vessel 10 are thermally insulated with high density
foam, polystyrene foam, or other high R value insulator (not
30 shown). The heat exchange coil in this case comprises copper
tubing in liquid communication with a cooling pump that
circulates cooling liquid such as chilled ethylene glycol, etha-
nol, acetone, or freon to control temperature inside the mixer.
The vessel volume 14 is set by positioning a piston-like clo-
35 sure lid, or follower plate, 20 at a set distance from the bottom
of the vessel and securing it in place by compression of
o-rings 24. Follower plate 20, comprises a heat exchange coil
22 or a void volume for circulating a cooling liquid. This
40 arrangement provides temperature control on all surfaces in
contact with vessel lumen volume 14. A rod 30, attached
externally to a pneumatic actuator, goes through the center of
the closure-lid and attaches to a perforated churn-plate 40. In
this example, the churn-plate has thirty-six, 6 mm diameter
45 holes and is pneumatically cycled up and down, through the
entire mixer volume. Ports 50 and 60 are for connection to a
liquefied gas transfer tank and vacuum pump, respectively.
The ability to evacuate the mixing chamber before the intro-
duction of liquefied gas prevents the formation of bubbles
5o during the mixing process. A third port 70 is located at the
bottom of the mixer for removing GLP or other gelled product
from the mixer and can also be used to in some embodiments
as a port for filling the chamber in a manner similar to filling
a syringe. Pneumatically actuated zero void volume valves
55 52, 62, and 72 are used to regulate flow through ports 50, 60,
and 70, respectively. Two thermocouples 80 and two pressure
sensors, not shown, are used to monitor temperature and
pressure inside the vessel.
The churn mixer may be scaled up or down to 500 liters,
6o 200 liters, 50 liters, 10 liters, or 0.5 liters, for example. The
mixing vessel components may be made of any material
resistant to the chemicals, temperatures and pressures used in
the gelling process. In the present example, the mixer and
transfer tank are made of aluminum. Other materials such as
65 stainless steel may and borosilicate glass may also be used.
Pneumatically actuated zero void volume valves are preferred
but other types of valves may be used.
US 8,047,703 B2
3
EXAMPLE 1
Gelling Liquid Propane
A schematic of the components used in the gelling method
is shown in FIG. 2 and comprises an aluminum storage tank 5
located on scale 15, vacuum pump 25, churn mixer vessel 10,
connecting lines 35, cooling bath 45 for circulating ethanol
chilled with dry ice, and valves 52, 62, 72, and 82. The outer
surfaces of mixer vessel 10 and the follower plate (not shown)
are insulated with a removable, high-density foam insulating
material. Connecting lines 35 are flexible, stainless steel
braided lines coated with Teflon®.
20 grams of Cabot M-58 fumed silica were placed in
mixing vessel 10. The follower plate was lowered into the
mixing vessel until the churn plate contacted the gellant. The
vessel was sealed by compressing o-rings in the flower plate.
Transfer tank 5 and mixing vessel 10 were evacuated using
vacuum pump 25 with valve 72 closed and valves 52, 62, and
82 open. Valves 52, 62, and 82 were then closed and LP was
transferred from an LP tank (not shown) into the evacuated
transfer tank through a fill valve (not shown). Scale 15 was
used to monitor the mass of the propane in the aluminum tank
during transfer. The fill valve was then closed.
The temperature inside the transfer tank and mixing vessel
was lowered to —45° C. to prepare the propane gel mixer for
propane transfer. The mixer was cooled after vacuum was
reached in order to prevent condensation inside the mixer.
Valve 82 was slowly opened to fill connecting line 35 between
the transfer tank and the mixer. The mass of LP lost from the
transfer tank to the transfer line was recorded. Valve 52 was
slowly opened to allow LP from transfer tank 5 into mixing
vessel 10. The follower plate was pulled upward by a pneu-
matic actuator to draw liquid propane into the mixing vessel
until 500 grams of propane was transferred into the mixer and
valve 52 was closed. LP and gellant were mixed with a churn
plate frequency of 1 Hz for 2 minutes. Valve 72 was opened
and GLP was pressed from the mixer into a storage container
by moving the follower plate to the bottom of the mixing
vessel.
EXAMPLE 2
Gelling MON-30
The apparatus used is the same as for gelling liquid propane
with the exception that the o-rings (24 in FIG. 1) were made
of the MON-resistant material Kalrez(k. Storage tank 5 was
filled with MON-30 from a holding tank rather than LP and
the temperature in the mixer was maintained between —I' C.
and —8° C.
It is possible to gel liquefied gasses having lower boiling
points and higher vapor pressures than LP as long as the
combination of temperature and pressure in the mixing cham-
ber maintain the liquefied gas in the liquid state. Extremely
low temperatures can be achieved by using liquid nitrogen or
liquid helium as the circulating fluid for heat exchange.
The above examples are presented for illustrative purposes
to describe the present apparatus and method. Although par-
ticular embodiments of the present invention have been
4
described, it is not intended that such references be construed
as limitations upon the scope of this invention except as set
forth in the following claims.
The invention claimed is:
5	 1. A Method for gelling a liquefied gas comprising the steps
of:
a) placing a gellant in a plate churn mixer,
b) applying a vacuum to the plate churn mixer,
c) cooling the plate churn mixer to a temperature less than
10	 0° C.,
d) introducing liquefied gas into the plate churn mixer, and
e) mixing the gellant with the liquefied gas while maintain-
ing the plate churn mixer at a temperature of less than 0°
C. to form a gelled liquefied gas
15	 wherein said plate churn mixer comprises:
a cylindrical mixing vessel that is open at one end and
sealed at the other end and comprising a means for
circulating heat exchange fluid within walls of the mix-
ing vessel,
20 a closure lid that fits inside the open end of the mixing
vessel, said closure lid comprising an opening and
o-rings configured to seal the closure lid against the
inside walls of the mixing vessel upon compression of
the o-rings and means for circulating a heat exchange
25	 fluid within the closure lid,
a rod passing through the opening in the closure lid and
attached to a perforated plate located inside the mixing
vessel and mechanically coupled to a means for moving
the perforated plate back and forth between the ends of
30	 the mixing vessel,
at least one valved port in the mixing vessel or closure lid
configured for delivering liquefied gas into or removing
gelled liquefied gas from the mixing vessel, and
at least one valved port in the mixing vessel or closure lid
35	 configured for evacuating the mixing vessel, and
a supply of heat exchange fluid in fluid communication
with said means of circulating heat exchange fluid in the
walls of the vessel and the closure lid, said supply of heat
exchange fluid being configured to maintain said heat
40	 exchange fluid at a temperature of 0° C. or lower.
2. The method of claim 1, wherein the plate churn mixer
has a volume of between 0.1 liter and 500 liters.
3. The method of claim 1, wherein the liquefied gas is
propane or a mixed oxide of nitrogen.
45	 4. The method of claim 1, wherein the gellant is silicon
dioxide, clay, carbon, or an organic or inorganic polymer.
5. The method of claim 4, wherein the gellant is doped with
one or more dopants.
6. The method of claim 5, wherein the one or more dopants
5o are selected from the group consisting of boron, carbon,
lithium, aluminum, and titanium.
7. The method of claim 1, wherein the plate churn mixer is
cooled to and maintained at a temperature of —45° C.
8. The method of claim 1, wherein the perforated plate
55 consists of a metal plate comprising holes having diameters of
between 4 and 8 mm.
9. The method of claim 1, wherein the gelled liquefied gas
is a rocket propellant.


Apparatus and method for gelling liquefied gasses

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