U.S. patent application number 10/459842 was filed with the patent office on 2004-12-16 for aviation fuel cold flow additives and compositions.
This patent application is currently assigned to General Electric Company. Invention is credited to Carey, William S., Chang, Zen-Yu, Deng, Fang, Eldin, Sherif, Goliaszewski, Alan E..
Application Number | 20040250468 10/459842 |
Document ID | / |
Family ID | 33510883 |
Filed Date | 2004-12-16 |
United States Patent
Application |
20040250468 |
Kind Code |
A1 |
Deng, Fang ; et al. |
December 16, 2004 |
Aviation fuel cold flow additives and compositions
Abstract
Aviation fuel, such as jet fuel, blends and methods for
improving cold flow properties of such fuels at extremely low
temperatures are disclosed. Cold flow properties of, for example,
JP-8 jet fuel are improved by addition to the fuel of an
oil-soluble, polar nitrogen-containing compound. Demonstratable
cold flow improvement of such fuels at temperatures of about
-53.degree. C. and lower is shown.
Inventors: |
Deng, Fang; (Drexel Hill,
PA) ; Carey, William S.; (Wallingford, PA) ;
Chang, Zen-Yu; (North Wales, PA) ; Eldin, Sherif;
(Houston, TX) ; Goliaszewski, Alan E.; (The
Woodlands, TX) |
Correspondence
Address: |
WEGMAN, HESSLER & VANDERBURG
6055 ROCKSIDE WOODS BOULEVARD
SUITE 200
CLEVELAND
OH
44131
US
|
Assignee: |
General Electric Company
Fairfield
CT
|
Family ID: |
33510883 |
Appl. No.: |
10/459842 |
Filed: |
June 12, 2003 |
Current U.S.
Class: |
44/412 |
Current CPC
Class: |
C10L 1/224 20130101;
C10L 1/22 20130101; C10L 1/221 20130101 |
Class at
Publication: |
044/412 |
International
Class: |
C10L 001/22 |
Claims
What is claimed is:
1. Method of improving the cold flow rate of jet fuel comprising
adding to said jet fuel an effective amount of the purpose of a
cold flow rate enhancement agent (CFREA) comprising an oil-soluble,
polar, nitrogen-containing compound.
2. Method as recited in claim 1 comprising adding from a 1-7,500 mg
of said CFREA to said jet fuel, based upon 1 liter of said jet
fuel.
3. Method as recited in claim 1 wherein said jet fuel is a JP-8
based jet fuel.
4. Method as recited in claim 1 wherein said oil-soluble, polar
nitrogen compound comprises an amine salt or amide.
5. Method as recited in claim 4, wherein said oil-soluble, polar
nitrogen compound comprises a reaction product formed from reaction
of a hydrocarbyl acid having two or more carboxyl groups or
anhydride thereof, and a hydrocarbyl secondary amine followed by
neutralization of the resulting product with a hydrocarbyl primary
amine.
6. Method as recited in claim 1 wherein said oil-soluble, polar
nitrogen compound is benzoic acid, 2-[(bis(hydrogenated tallow
alkyl)amino)carbonyl]-C.sub.16-C.sub.22 tert-alkyl amine salt.
7. Method as recited in claim 2 wherein said oil-soluble, polar
nitrogen-containing compound is represented by the formula 3wherein
Z is a divalent organic radical, and R.sub.1, R.sub.2, and R.sub.3
are independently chosen from C.sub.10-C.sub.40 hydrocarbyl
groups.
8. Method as recited in claim 2 wherein said oil-soluble, polar,
nitrogen-containing compound is formed from a reaction of a
hydrocarbyl acid having from about 1 to about 4 carboxyl groups or
anhydrides thereof with a hydrocarbyl substituted primary,
secondary, or tertiary amine.
9. Method as recited in claim 8 wherein said hydrocarbyl acid or
anhydride and hydrocarbyl substituted primary, secondary, and
tertiary amines each have from about 4 to about 24 carbon
atoms.
10. Method as recited in claim 9 wherein said hydrocarbyl acid or
anhydride and hydrocarbyl substituted primary, secondary, and
tertiary amines each have from about 10-24 carbon atoms.
Description
FIELD OF THE INVENTION
[0001] The invention pertains to jet fuel blends and methods in
which a cold flow enhancement agent is added to the jet fuel to
improve fuel flow rates and flow characteristics at low fuel
temperatures.
BACKGROUND OF THE INVENTION
[0002] It is important that aviation fuel exhibits a freeze point
that is sufficiently low to allow adequate fuel flow through fuel
system lines and filters to the engine. It is known that fuel
temperature decreases as flight time increases and that longer
duration flights typically require lower freezing point fuels than
do shorter duration flights.
[0003] Additionally, high altitude flights, such as those conducted
under military operational conditions, also require lower freezing
point fuels than do lower altitude conventional flights. Quite
obviously then, there is a need to provide freeze point
depressant/cold flow enhancement aids for aviation fuels,
particularly for jet fuels, which will allow for sufficient fuel
flow to desired combustion locations at the extremely low fuel
temperatures encountered at high altitude and long duration
flights. Publications WO 01/32811 A1 and WO 01/62874 A2 discuss
details of aviation fuels and the need for lowered freeze point
fuel blends.
[0004] One such means of enhancing the cold flow properties of wax
containing hydrocarbon fluids is via use of polymeric pour point
depressant additives. For example, use of poly[(meth)acrylates] as
a pour point depressant for hydrocarbon lubricating oil is taught
by U.S. Pat. Nos. 5,312,884 and 5,368,761. Additionally, the use of
poly[.alpha.-olefins] to improve the cold flow properties of gas
oil is taught by E1-Gamal et al., J. of Polym. Sci. 61, pp.
1265-1272 (1966). The use of a low molecular weight highly branched
polymer of normal .alpha.-olefin to improve the cold flow
properties of residual fuel oil is taught in U.S. Pat. No.
4,022,590.
[0005] The use of nitrogen compounds, such as amides, amine salts,
and ammonium salts of carboxylic acids or anhydrides, or sulpho
anhydrides, as an adjuvant to polymeric pour point additives in
middle distillate fuels is also known to those skilled in the art.
These compounds act as wax crystal modifiers and/or
anti-agglomeration agents to provide enhanced cold flow properties
relative to the polymeric pour point additive as a stand-alone
treatment. For example see U.S. Pat. Nos. 3,982,909; 4,211,534; and
5,516,443; and EP applications Nos. 0 261 959 A2; 0 261 957 A2; and
0 272 889 A2.
[0006] WO 01/62874 A2 teaches the use of various chemical
additives, including certain copolymers of vinyl acetate and
ethylene, to lower the freeze point of aviation fuels. It is
further taught that certain classes of pour point additives known
to those skilled in the art for treating middle distillates, such
as heating oils and diesel fuels, are not necessarily effective in
the treatment of aviation fuel and actually may be detrimental.
DESCRIPTION OF THE INVENTION
[0007] Methods for improving the cold flow rate of aviation fuels,
and jet fuels in particular are provided wherein the jet fuel is
blended with a cold flow rate enhancement agent (CFREA). The CFREA
is an oil-soluble, polar, nitrogen-containing compound.
[0008] The oil-soluble, polar nitrogen-containing compounds are set
forth in U.S. Pat. No. 4,211,534 (Feldman) incorporated by
reference herein. Basically, as stated in the '534 specification,
these compounds are oil-soluble amine salts and/or amides that are
generally formed by reaction of at least one molar proportion of
hydrocarbyl acid having 1-4 carboxyl groups or their anhydrides,
with a hydrocarbyl substituted primary, secondary, and/or tertiary
amine.
[0009] In the case of the polycarboxylic acids, or anhydrides, all
of the acid groups may be converted to amine salts or amides, or
part of the acid groups may be left unreacted.
[0010] The term "hydrocarbyl" as defined in U.S. Pat. No. 4,211,534
includes groups that may be branched or straight chain, saturated
or unsaturated, aliphatic, cycloaliphatic, aryl, alkaryl,
substituted derivatives thereof and the like. Typically, these
hydrocarbyl groups will consist from about 4-24 carbon atoms, more
preferably 10-20 carbon atoms. In general, the resultant compound
should contain sufficient hydrocarbyl content so as to be soluble
in the fuel matrix.
[0011] Exemplary hydrocarbyl substituted acids and anhydrides
include, but are not limited to, hexanoic acid, lauric acid,
palmitic acid, steric acid, behenic acids, benzoic acids,
1,2,4,5-benzenetetracarboxylic dianhydride,
1,2-cyclohexanedicarboxylic anhydride, ethylenediaminetetraacetic
dianhydride, salicylic acid, succinic acid, succinic anhydride,
alkenyl succinic anhydrides, polyisobutenyl succinic anhydrides
(PIBSA), phthalic acids, phthalic anhydride, naphthenic acids,
naphthenic anhydrides, and the like. Particularly preferred is
phthalic anhydride.
[0012] The hydrocarbyl substituted amines may be primary,
secondary, or tertiary; preferably primary or secondary.
[0013] Exemplary hydrocarbyl substituted primary amines include,
but are not limited to, coco amine, tallow amine, hydrogenated
fatty primary amine, 2-ethylhexylamine, n-dodecyl amine,
C.sub.12-14 or C.sub.16-22 tertiary alkyl primary amines from Rohm
and Haas Company marketed under the trade name Primene.RTM.,
mixtures thereof and the like. Particularly preferred is the
C.sub.16-22 tertiary alkyl primary amine marketed by Rohm and Haas
Company under the trade name Primene.RTM. JM-T.
[0014] Exemplary hydrocarbyl substituted secondary amines include,
but are not limited to, dicocoalkylamine, didecylamine,
dioctadecylamine, ditallowamine, dihydrogenated tallowalkylamine,
mixtures thereof and the like. Particularly preferred is
dihydrogenated tallowalkylamine which is commercially available
from Akzo Nobel Corporation under the trade name Armeen.RTM.
2HT.
[0015] As would be understood by one skilled in the art in view of
the present disclosure, it is intended that the aforementioned
examples do not in any way limit the description of the
nitrogen-containing compounds. Furthermore, it is to be understood
that ester analogs derived from a hydrocarbyl alcohol, and
hydrocarbyl sulfo acid analogs such as those derived from
o-sulphobenzoic acid or its anhydride, are also within the purview
of the present invention.
[0016] An especially preferred group of polar nitrogen-containing
compounds are mixed amine salt/amides derived from reaction of
hydrocarbyl acid (having two or more carboxyl groups) or its
anhydrides as set forth above with a hydrocarbyl secondary amine.
The resulting intermediate amide acid is then neutralized with a
primary amine.
[0017] Generally, the preferred group of polar nitrogen containing
compounds can be represented by the formula 1
[0018] wherein Z is a divalent organic radical, and R.sub.1,
R.sub.2 and R.sub.3 are independently chosen from C.sub.10-C.sub.40
hydrocarbyl groups. The hydrocarbyl groups include straight or
branched chain, saturated or unsaturated aliphatic, cycloaliphatic,
aryl or alkylaryl moieties. These hydrocarbyl groups may contain
other groups or atoms such as hydroxy groups, carbonyl groups,
ester groups, oxygen, sulfur, or chlorine groups. As stated above,
the hydrocarbyl groups may be on the order of C.sub.10-C.sub.40
with the range of C.sub.14-C.sub.24 even more preferred. The
R.sub.1, R.sub.2, and R.sub.3 groupings can also represent mixtures
of different hydrocarbyl groups. Preferably, R.sub.3.noteq.R.sub.1
or R.sub.2.
[0019] The resulting compound should contain sufficient hydrocarbon
content to be oil-soluble.
[0020] The preferred oil-soluble, polar nitrogen-containing
compound is prepared by initial reaction of a hydrocarbyl acid or
its anhydride and a secondary amine, such as the Armeen.RTM. 2HT.
Then, the resulting mixed amine salt/amide is neutralized with a
primary amine such as the commercially available Primene.RTM. JM-T
product. Approximately equimolar amounts of the reactants are used,
resulting in a mixed substituted amide/amine salt.
[0021] The most preferred polar nitrogen containing compound is an
oil-soluble mixed amide/amine salt formed via reaction of equimolar
amounts of phthalic anhydride with the secondary amine, Armeen.RTM.
2HT. The product of this reaction is then further reacted with an
equimolar amount of the primary amine, Primene.RTM. JM-T to form
benzoic acid, 2-[(bis(hydrogenated tallow alkyl)amino)
carbonyl]-C.sub.16-C.sub.22 tert-alkyl amine salt having the
structural formula: 2
[0022] wherein R.sub.1 and R.sub.2 are mixtures of C.sub.16 and
C.sub.18 hydrocarbons from the commercially available tallowamine
product, and R.sub.3 is a mixture of C.sub.18-22 hydrocarbons from
the commercially available Primene.RTM. JM-T product.
[0023] The CFREAs of the present invention should be added to an
aviation fuel, for which improved cold flow performance is desired,
in an amount effective for the purpose. In the preferred embodiment
of the invention, the aviation fuel is selected from Jet Fuel A,
Jet Fuel A-1, Jet Fuel B, JP-4, JP-8, and JP-8+100. Most preferably
the jet fuel is a JP-8 based fuel such as neat JP-8 or the
formulated JP-8+100.
[0024] Jet Fuel A and Jet Fuel A-1 are kerosene-type fuels with Jet
Fuel B being a "wide cut" fuel. Jet A is used for many domestic
commercial flights in the U.S. Most preferably, the CFREAs of the
invention are used to increase the cold flow characteristics of
military jet fuels such as JP-5, JPTS, JP-7, JP-8, and JP-8+100.
JP-5 is currently used by the U.S. Navy with JP-8 and JP-8+100 used
by the Air Force.
[0025] These fuel types are described in the following Table 1.
1TABLE 1 U.S. Military Jet Fuel Year Freeze Point Flash Fuel
Introduced Type .degree. C. Max Point Comments JP-5 1952 kerosene
-46 60 U.S. Navy obsolete JPTS 1956 kerosene -53 43 High thermal
stability JP-7 1960 kerosene -43 60 Lower higher thermal stability
JP-8 1979 kerosene -47 38 U.S. Air Force JP-8 + 100 1998 kerosene
-47 38 U.S. Air Force contains additives for improved thermal
stability JP = jet propulsion Source: Chevron "Aviation Fuels"
Technical Review.
[0026] On a 100% actives basis, the CFREA is preferably added to
the jet fuel in an amount of about 1-7,500 mg/L of the jet fuel.
More preferably, the CFREA is added in an amount of between about
200-5,000 mg/L, most preferably about 4,000 mg/L. The jet
fuel/CFREA blend is capable of improving the cold flow rate of jet
fuel, specifically, JP-8 based jet fuel, at fuel temperatures on
the order of about -53.degree. C. and below. Experimental results
have indicated that the CFREAs when blended with JP-8 based jet
fuel in accordance with the invention improve cold flow rates of
the fuel so that they are, as measured in accordance with Table 2
and the test system described, on the order of about 0.60 (g/s) and
greater at fuel temperatures of about -53.degree. C. and lower.
[0027] The CFREAs of the invention can be employed in combination
with conventional fuel additives such as dispersants, antioxidants,
and metal deactivators. Such additives are known to those skilled
in the art, for example see U.S. Pat. Nos. 5,596,130 and
5,614,081.
[0028] The invention will be described further in conjunction with
the following examples that are included for illustrative purposes
only and should not be construed to limit the invention.
EXAMPLE 1
Preparation of Benzoic Acid, 2-[(bis(hydrogenated tallow
alkyl)amino)carbonyl]-C.sub.16-C.sub.22 tert-alkyl Amine Salt
[0029] To a four-necked reaction flask equipped with a mechanical
overhead stirrer, thermocouple, reflux condenser, nitrogen sparge
tube, addition port with septum and a heating mantle was added
phthalic anhydride (99%, 5.0 g, 0.03342 mole) and Armeen.RTM. 2HT
(17.0 g, 0.03342 mole amine). The resulting wax mixture was then
heated to 90.degree. C. under nitrogen with mixing and held for
four hours. Primene.RTM. JM-T (10.9 g, 0.03342 mole amine) was then
added to the reactor at 90.degree. C. over an eight-minute period,
after which the batch was maintained at 90.degree. C. for an
additional four hours before cooling to room temperature to yield a
wax like material. This was then diluted in Aromatic 100 to yield a
25 wt % solution of the nitrogen-containing compound.
EXAMPLE 2
Preparation of Benzoic Acid, 2-[(bis(hydrogenated tallow
alkyl)amino)carbonyl]-C.sub.16-C.sub.22 tert-alkyl Amine Salt
[0030] This preparation was a scaleup of Example 1 (basis: phthalic
anhydride, 99%, 344.74 g, 2.30 mole) except the hold times after
the Armeen.RTM. 2HT and Primene.RTM. JM-T additions were decreased
to one-hour each.
Cold Flow Additive Testing
[0031] JP-8 jet fuel was then treated with a known amount of
additive solution and subjected to cold flow testing. Cold flow
tests were conducted utilizing a Cold Additive Screening Test
(CAST) and low temperature viscometer apparatus.
[0032] In general, the CAST apparatus consists of two 500 ml
flasks, one at atmospheric pressure and one sealed, connected via a
1/4" Teflon tube. A known amount of fuel is charged to the flask at
atmospheric pressure, and the apparatus is cooled to the desired
test temperature in an environmental chamber. Once cooled to the
desired temperature vacuum (2" Hg) is applied to the sealed flask.
The to the desired temperature vacuum (2" Hg) is applied to the
sealed flask. The effectiveness of an additive is determine by
measuring the time it takes for the fuel to flow to the sealed
flask, and the amount of fuel remaining in the atmospheric flask
after the fuel flow ceases.
[0033] Screening results of the additives of the present invention
in the CAST apparatus are provided in Table 2 below. At
approximately -53.degree. C. the untreated fuel has solidified and
exhibited 100% holdup and essentially no fuel flow. Addition of the
additives of the present invention to the fuel dramatically
improved the cold flow properties at approximately -53.degree. C.
as evidenced by a substantial decrease in hold up and increase in
fuel flow.
2TABLE 2 CAST Testing Results Conc. Fuel Temp Holdup Flow Rate
Additive 1 (mg/L)* (.degree. C.) (%) (g/s) None N/A -53.5 100 N/A
Example 1 8000 -52.7 10 1.34 Example 1 16000 -53.3 9 0.93 Example 2
12000 -57.8 25 0.47 Example 2 12000 -55.1 7 0.85 Example 2 14000
-57.0 13 0.83 Example 2 14000 -55.2 10 1.06 Example 2 16000 -57.1 8
0.82 Example 2 16000 -55.2 8 0.93
[0034] Low temperature viscosity studies of the treated fuel were
carried out using a scanning Brookfield Viscometer in the
temperature range of -5.degree. C. to -60.degree. C. as described
by S. Zabarnick and M. Vangsness, Petroleum Chemistry Preprints
2002, 47(3), pp. 243-246 (2002). The results of this testing are
given in Table 2. The knee temperature is defined as the
temperature at which a rapid viscosity increase occurs due to
crystal formation. It is desirable to have the "knee temperature"
for a treated fuel to be shifted to a lower temperature relative to
the neat fuel. It is also highly desirable to minimize the rate of
viscosity increase as the fuel is cooled below the knee
temperature.
[0035] Table 3 summarizes the results for the low temperature
viscosity studies. The letter designation corresponds to the
viscosity curve for that treatment in the companion graph presented
in FIG. 1. It can be seen from the data presented that the
additives of the present invention lower the knee temperature of
the fuel. Additionally, as shown in FIG. 1, addition of the
additives of the invention significantly reduces the rate of
viscosity increase. The effect is pronounced to the extent that at
higher additive levels there was no obvious knee temperature (curve
"C" of FIG. 1).
3TABLE 3 Low TemperatureViscosity Results-Knee Temperature in JP-8
Fuel Conc. Ledtter Additive 1 (mg/L)* Knee Temp (.degree. C.) A
None N/A -52.0 B Example 2 12000 -55.2 C Example 2 16000 None
Observed
[0036] While the specification above has been drafted to include
the best mode of practicing the invention as required by the patent
statutes, the invention is not to be limited to that best mode or
to other specific embodiments set forth in the specification. The
breadth of the invention is to be measured only by the literal and
equivalents constructions applied to the appended claims.
* * * * *