U.S. patent application number 13/522008 was filed with the patent office on 2012-11-22 for protection of liquid fuels.
This patent application is currently assigned to PALOX LIMITED. Invention is credited to Matthias Kiefer, David William Martin, Gunter Oetter, Dietmar Posselt.
Application Number | 20120291339 13/522008 |
Document ID | / |
Family ID | 42082556 |
Filed Date | 2012-11-22 |
United States Patent
Application |
20120291339 |
Kind Code |
A1 |
Martin; David William ; et
al. |
November 22, 2012 |
PROTECTION OF LIQUID FUELS
Abstract
A liquid concentrate comprising essentially: (A) 0.1 to 10 wt. %
of one or more amphoteric emulsifying agents; (B) 30 to 95 wt. % of
one or more nonionic alkoxylated surfactants; (C) 0 to 20 wt. % of
one or more glycol-based solubilizers; and (D) 0 to 65 wt. % of one
or more organic solvents; wherein component (B) comprises a mixture
of C.sub.6-C.sub.15-alkanol ethoxylates with different carbon
numbers for the alkanol unit species, the carbon numbers for the
two C.sub.6-C.sub.15-alkanol ethoxylates which have the highest
share in weight in the mixture being at least 1.5 carbon numbers
distant from each other, is useful for reducing or eliminating the
formation in a liquid hydrocarbon fuel of ice particles having a
weight average particle size greater than 1 .mu.m when said liquid
hydrocarbon fuel is cooled to temperatures in the range of from 0
to -50.degree. C.
Inventors: |
Martin; David William;
(Liverpool, GB) ; Posselt; Dietmar; (Heidelberg,
DE) ; Oetter; Gunter; (Frankenthal, DE) ;
Kiefer; Matthias; (Ludwigshafen, DE) |
Assignee: |
PALOX LIMITED
Limassol
CY
|
Family ID: |
42082556 |
Appl. No.: |
13/522008 |
Filed: |
February 7, 2011 |
PCT Filed: |
February 7, 2011 |
PCT NO: |
PCT/GB2011/050206 |
371 Date: |
July 12, 2012 |
Current U.S.
Class: |
44/302 ;
44/353 |
Current CPC
Class: |
C10L 1/2222 20130101;
C10L 2250/084 20130101; C10L 2270/04 20130101; C10L 1/143 20130101;
C10L 1/1826 20130101; C10L 1/328 20130101; C10L 2200/043 20130101;
C10L 1/1824 20130101; C10L 1/1985 20130101; C10L 2200/0254
20130101 |
Class at
Publication: |
44/302 ;
44/353 |
International
Class: |
C10L 1/32 20060101
C10L001/32; C10L 1/18 20060101 C10L001/18 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2010 |
GB |
1001923.0 |
Claims
1. A liquid concentrate comprising essentially (A) 0.1 to 10 wt. %
of one or more amphoteric emulsifying agents; (B) 30 to 95 wt. % of
nonionic alkoxylated surfactants; (C) 0 to 20 wt. % of one or more
glycol-based solubilizers; and (D) 0 to 65 wt. % of one or more
organic solvents; wherein component (B) comprises a mixture of
C.sub.6-C.sub.15-alkanol ethoxylates with different carbon numbers
for the alkanol unit species, the carbon numbers for the two
C.sub.6-C.sub.15-alkanol ethoxylates which have the highest share
in weight in the mixture being at least 1.5 carbon numbers distant
from each other.
2. The concentrate as claimed in claim 1 comprising (A) 0.1 to 10
wt. % of one or more betaine-based emulsifying agents; (B) 30 to 95
wt. % of C.sub.6-C.sub.15-alkanol ethoxylate surfactants; (C) 0 to
20 wt. % of one or more glycol-based solubilizers; and (D) 0 to 65
wt. % of one or more organic solvents.
3. The concentrate as claimed in claim 2 comprising (A) 0.5 to 5
wt. % of one or more fatty
(C.sub.8-C.sub.24)-amido-(C.sub.1-C.sub.6)-alkyl betaine
emulsifying agents; (B) 45 to 75 wt. % of C.sub.6-C.sub.15-alkanol
ethoxylate surfactants; (C) 0.5 to 10 wt. % of one or more
glycol-based solubilizers; and (D) 5 to 50 wt. % of one or more
organic solvents.
4. The concentrate as claimed in claim 1 comprising cocoamidopropyl
betaine as component (A).
5. The concentrate as claimed in claim 1 comprising as component
(B) one or more C.sub.6-C.sub.15-alkanol ethoxylates with 2 to 5
moles of ethylene oxide units on average per mole of alkanol.
6. The concentrate as claimed in claim 1 comprising as component
(B) one or more C.sub.6-C.sub.15-alkanol ethoxylates with an
average degree of methyl branching for the alkanol unit of 3.7 or
less.
7. The concentrate as claimed in claim 1 comprising one or more
C.sub.9-C.sub.14-alkanol ethoxylates as component (B).
8. The concentrate as claimed in claim 7 comprising one or more
C.sub.9-C.sub.14-alkanol ethoxylates with 2 to 12 moles of ethylene
oxide units on average per mole of alkanol as component (B)
9. The concentrate as claimed in claim 1, wherein the carbon number
for one of the two C.sub.6-C.sub.15-alkanol ethoxylates which have
the highest share in weight in the mixture is in the range of 9 to
11 and the other is in the range of 12 to 14.
10. The concentrate as claimed in claim 1 comprising ethylene
glycol as component (C).
11. The concentrate as claimed in claim 1 comprising one or more
C.sub.1-C.sub.4 alkanols as component (D).
12. The concentrate as claimed in claim 11 comprising ethanol as
component (D).
13. The process for manufacturing a concentrate as claimed in claim
1, characterised in that components (A) to (D) are mixed together
at a temperature in the range of from -10.degree. C. to 60.degree.
C., preferably 0.degree. C. to 40.degree. C.
14. A stable water-in-oil-emulsion comprising (a) a liquid fuel or
oil which is immiscible with water; (b) up to 1 wt. %, preferably
up to 0.1 wt. %, based on the amount of (a), water; and (c) 10 to
10,000 wt. ppm, preferably 10 to 1,000 wt. ppm, based on the amount
of (a), of a concentrate as claimed in claim 1.
15. The water-in-oil-emulsion as claimed in claim 14 which is a
water-in-oil-micro-emulsion.
16. The stable water-in-oil-emulsion or water-in-oil-microemulsion
as claimed in claim 14, characterised in that the liquid fuel or
oil is a jet fuel or kerosene.
17. The use in a liquid fuel or oil for a turbine engined aircraft
of a concentrate as claimed in claim 1, wherein said liquid fuel or
oil is immiscible with water, characterised in that said use is to
scavenge free water which exists in or is introduced into the said
liquid fuel or oil as a contaminant by forming a stable
water-in-oil-emulsion or water-in-oil-microemulsion, thereby to
render or retain the said liquid fuel or oil in a usable state.
18. The use as claimed in claim 17, characterised in that the
liquid fuel or oil is a jet fuel or kerosene.
19. A method of scavenging free water which exists in or is
introduced as a contaminant into a liquid fuel or oil which is
immiscible with water, thereby to render or retain the said liquid
fuel or oil in a usable state, which method comprises: adding to a
substantially water-free liquid fuel or oil or to a liquid fuel or
oil contaminated with free water a concentrate as claimed in claim
1 in order to form a stable water-in-oil-emulsion or
water-in-oil-microemulsion.
20. The method as claimed in claim 19, characterised in that the
liquid fuel or oil is a jet fuel or kerosene.
21. The stable water-in-oil-emulsion or water-in-oil-microemulsion
as claimed in claim 15, characterised in that the liquid fuel or
oil is a jet fuel or kerosene.
Description
FIELD OF THE INVENTION
[0001] The present invention concerns the protection of liquid
fuels, such as liquid fuels typically used in engines employed to
provide motive power in vehicles such as, although not limited,
turbine engined aircraft. In particular, the present invention is
concerned with the protection of such liquid fuels from the
deleterious effects of contamination by water, such as the effect
on engines caused by the presence of water as a separate phase in a
fuel. The present invention more importantly provides protection to
liquid fuels from ice formation, thereby reducing the potential for
ice slugs to be drawn in to the engine.
[0002] The present invention also concerns compositions, a method
for their preparation and use and concentrates. More particularly,
though not exclusively, the present invention concerns water-in-oil
microemulsions, such as are suitable for use as a fuel for a
turbine engine aircraft, and its preparation.
[0003] In summary, the present invention concerns clear aqueous
compositions which comprise at least 99 wt % of a liquid fuel and
concentrates useful in the preparation of such compositions, which
compositions are useful as a fuel for turbine engine aircraft, such
as water-in-oil emulsions wherein the average droplet size of the
water phase in the oil phase is no greater than 0.25 m, preferably
no greater than 0.1 m, and their preparation.
BACKGROUND OF THE INVENTION
[0004] Jet fuel often becomes contaminated in a fuel tank of a
turbine engine aircraft with small quantities of free water from
condensation arising from the changes in temperature due to
altitude changes. On the ground the fuel/tank temperature can range
from -18.degree. C. to +40.degree. C., whilst in flight it
typically ranges from -22.degree. C. to -39.degree. C.
[0005] Over a number of temperature change cycles, for example over
a number flights, condensation of the water vapour can give rise to
the accumulation of water within the fuel tank which may exist as a
separate phase or free water within the fuel. If the free water is
permitted to pool and freeze in the fuel tank, it can form slugs of
ice (ice particles of sufficient size such that they may be trapped
in the fuel filtering system) which can be potentially harmful to
the function of the aircraft engines. Indeed, it is believed a
Boeing 777 aircraft lost sufficient power to cause an emergency
landing at Heathrow in January 2008 due to the formation of ice
reducing the flow of fuel from the fuel tanks to the engines (AAIB
interim report No 2 G-YMMM).
[0006] At present, as an alternative to employing fuel tank
heaters, materials such as diethylene glycol monomethyl ether
(DiEGME) are mixed with aircraft fuel to prevent ice formation in
the fuel. Whilst DiEGME is about equally miscible in both water and
fuel at temperatures above freezing, careful monitoring during the
mixing process must be adhered to at all times to ensure an initial
homogenous fuel. However, no matter how carefully mixed, DiEGME has
a tendency at temperatures significantly below freezing to
preferentially concentrate in the water phase. Thus, due to
disproportionate distribution of DiEGME in the water and fuel at
low temperatures, insufficient DiEGME in the fuel phase can lead to
the formation of a separate aqueous phase (water and DiEGME) in the
fuel. The presence of the DiEGME in the aqueous phase will prevent
some of the water in this phase from turning to ice. However, the
DiEGME/water mixture has an unusual characteristic in that it forms
a gel like substance at low temperatures: the gel like substance is
commonly referred to as "apple jelly" in the aviation industry. The
US Federal Aviation Authority has attributed several aviation
accidents to the formation of this "apple jelly" material in
aircraft fuel tanks.
[0007] It is an object of the present invention to reduce or
eliminate the formation of ice slugs and apple jelly in fuel in the
fuel tanks of turbine engine aircraft.
[0008] The use of water as an additive in fuel oils to reduce
emissions of pollutants and to aid incorporation of other
beneficial performance additives has been known for many years. The
use of water as an additive in lubricant oils to improve the
cooling properties of e.g. cutting oils has also been known for
many years. Water is incorporated into the fuel and lubricant oils
in the form of a water-in-oil emulsion.
[0009] Water-in-oil emulsions formed with a large water droplet
size tend to have a milky appearance. These emulsions require a
number of secondary additives such as corrosion inhibitors and
bactericides to overcome problems associated with addition of the
water phase. These macroemulsions, due to their large water droplet
size, also tend to exhibit instability that leads to oil/water
separation. Naturally, this is unwelcome as it may lead to problems
with not only machine failure but also problems with ignition e.g.
in a diesel-engine.
[0010] Cutting oils, based on water-in-oil emulsions, have been
used to lubricate machine tools. The excellent coolant property of
the water has been demonstrated to improve the life of the tool.
However, the incorporation of water coupled with the instability of
macroemulsions give rise to other problems, such as the lubricity
of the oil, which is decreased with addition of water thereby
affecting the surface finish of the metal.
[0011] Water-in-oil emulsions formed with an average water droplet
size of 0.25 .mu.m or less, preferably of 0.1 .mu.m or less, more
preferably of from 0.03 .mu.m to 0.08 .mu.m (hereafter referred to
as "microemulsions") are translucent. A typical value for the
average water droplet size is about 0.04 .mu.m. This small droplet
size not only gives an appearance which is more aesthetically
pleasing to the user but also offers several major advantages over
the larger droplet-sized systems. These translucent or clear
microemulsions tend to be more stable than the larger droplet sized
milky macroemulsions, as the water droplets remain in dispersion
longer and do not readily undergo macro oil/water phase separation.
The small droplet size also appears to negate the need for both
corrosion inhibitors and bactericides.
[0012] U.S. Pat. No. 3,095,286 (Andress et al) discloses the
problem of water accumulation in fuel oil storage tanks, resulting
from the "breathing" of storage vessels, presenting a problem of
rusting. To inhibit sedimentation, screen clogging and rusting in
fuel oil compositions during storage it is disclosed to use a
compound selected from a phthalamic acid, a tetrahydrophthalamic
acid, a hexahydrophthalamic acid and a nadamic acid and their salts
of primary amines having between 4 and 30 carbon atoms per molecule
as an addition agent to the fuel oil. There is no disclosure of the
addition agents forming water-in-oil microemulsions of the fuel
oil.
[0013] U.S. Pat. No. 3,346,494 (Robbins et al) discloses the
preparation of microemulsions employing a selected combination of
three microemulsifiers, specifically a fatty acid, an amino alcohol
and an alkyl phenol.
[0014] FR-A-2373328 (Grangette et al) discloses the preparation of
microemulsions of oil and salt water by employing sulphur
containing surfactants.
[0015] U.S. Pat. No. 3,876,391 (McCoy et al) discloses a process
for preparing clear, stable water-in-petroleum microemulsions,
which may contain increased quantities of water-soluble additives.
The microemulsions are formed by use of both a gasoline-soluble
surfactant and a water-soluble surfactant. The only water-soluble
surfactants employed in the worked examples are ethoxylated
nonylphenols.
[0016] U.S. Pat. No. 4,619,967 (Emerson et al) discloses the use of
water-in-oil emulsions for emulsion polymerisation processes.
[0017] U.S. Pat. No. 4,744,796 (Hazbun et al) discloses stable
water-in-fuel microemulsions employing a cosurfactant combination
of tertiary butyl alcohol and at least one amphoteric, anionic,
cationic or nonionic surfactant. Cocoamidobetaines are disclosed as
possible amphoteric surfactants.
[0018] U.S. Pat. No. 4,770,670 (Hazbun et al) discloses stable
water-in-fuel microemulsions employing a cosurfactant combination
of a phenyl alcohol and at least one amphoteric, anionic, cationic
or nonionic surfactant. Cocoamidobetaines are disclosed as possible
amphoteric surfactants.
[0019] U.S. Pat. No. 4,832,868 (Schmid et al) discloses surfactant
mixtures useful in the preparation of oil-in-water emulsions. There
is no disclosure of any water-in-oil microemulsion comprising at
least 60 wt % oil phase.
[0020] U.S. Pat. No. 5,633,220 (Cawiezel) discloses the preparation
of a water-in-oil emulsion fracturing fluid including an
emulsifying agent sold by ICI under the trademark Hypermer
(Hypermer emulsifying agents are not disclosed as being
C.sub.6-C.sub.15 alcohol ethoxylates or mixtures thereof).
[0021] Mixtures of C.sub.6-C.sub.15 alcohol ethoxylates are
commercially available surfactants normally sold for use in the
preparation of e.g. washing detergents.
[0022] WO-A-9818884 discloses water-in-fuel microemulsions,
including examples of such emulsions comprising a C.sub.8 alcohol
ethoxylate, with 6 EO groups, mixed with a
polyglyceryl-4-monooleate, and mixtures of C.sub.9-C.sub.11 alcohol
ethoxylates mixed with either polyglyceryl oleates linear alcohols
or POE sorbitan alcohols. The presence of the polyglyceryl oleates
and POE sorbitan alcohols tend to have detrimental effects on the
viscosity properties of the emulsions which, in turn, has a
consequential detrimental effect on the lubricity properties of the
emulsion.
[0023] WO-A-9850139 discloses a water-in-oil microemulsion,
including a surfactant mixture comprising a fatty acid amine
ethoxylate, a C.sub.6-C.sub.15 alcohol ethoxylate and optionally a
tall oil fatty acid amine. The water-in-oil microemulsion may be an
industrial lubricant.
[0024] WO-A-0053699 discloses a water-in-oil microemulsion,
including emulsifying agents comprising a C.sub.6-C.sub.15 alcohol
ethoxylate, an amine ethoxylate and a polyisobutylsuccininide or
sorbitan ester. The water-in-oil microemulsion may be a fuel.
[0025] EP-A-1101815 discloses a fuel, particularly for diesel
engines, in microemulsion form, comprising a liquid fuel, an
emulsifier and an emulsive agent, the emulsive agent having an HLB
value higher than 9.
[0026] U.S. Pat. No. 6,716,801 discloses a stable, clear
water-in-oil microemulsion consisting of from about 5 to 40 wt %
aqueous phase and from about 95 to about 60 wt % non-aqueous phase.
The microemulsion includes from about 5 to 30 wt % emulsifiers
consisting of i) a mixture of C.sub.6-C.sub.15 alcohol ethoxylates
each comprising from 2 to 12 EO groups, ii) 0 to about 25 wt %
polyisobutylsuccinimide and/or sorbitan ester, and iii) 0 to about
90 wt % amine ethoxylate. The microemulsion is described to be
useful as a fuel and/or lubricant/coolant.
[0027] Mixtures of liquid emulsifying agents suitable for use in
the preparation of water-in-oil microemulsions are disclosed in
WO-A-07083106. Such mixtures, commonly referred to as concentrates,
comprise about 0.5 to about 15 wt % fatty
(C.sub.8-C.sub.24)-amido-(C.sub.1-C.sub.6)alkyl betaine, about 5 to
about 99 wt % C.sub.6-C.sub.15 alcohol ethoxylate comprising from 2
to 12 EO groups or a mixture of such alcohol ethoxylates,
preferably the mixture, 0.5 to about 15 wt %
(C.sub.6-C.sub.24)alkyl amine oxide and 0 or up to about 94 wt %
other non-ionic emulsifying agent based on the total weight of
emulsifying agent in the emulsion.
[0028] None of the above prior art references, however, discloses
the performance of water-in-oil emulsions at low temperatures.
SUMMARY OF THE INVENTION
[0029] The present invention, in its various aspects, is as set out
in the accompanying claims.
[0030] In a first aspect the present invention provides a liquid
concentrate comprising essentially:
(A) 0.1 to 10 wt. % of one or more amphoteric emulsifying agents;
(B) 30 to 95 wt. % of one or more nonionic alkoxylated surfactants;
(C) 0 to 20 wt. % of one or more glycol-based solubilizers; and (D)
0 to 65 wt. % of one or more organic solvents, wherein component
(B) comprises a mixture of C.sub.6-C.sub.15-alkanol ethoxylates
with different carbon numbers for the alkanol unit species, the
carbon numbers for the two C.sub.6-C.sub.15-alkanol ethoxylates
which have the highest share in weight in the mixture being at
least 1.5 carbon numbers, preferably at least 2.0 carbon numbers,
more preferably at least 2.5 carbon numbers, most preferably at
least 3.0 carbon numbers, distant from each other. Preferably, in
the mixture of C.sub.6-C.sub.15-alkanol ethoxylates, the carbon
number for one of the two C.sub.6-C.sub.15-alkanol ethoxylates
which have the highest share in weight in the mixture are in the
range of 9 to 11 for one and in the range of 12 to 14 for the
other. Each of the species of the C.sub.6-C.sub.15-alkanol
ethoxylates mixture can be independently from each other an
ethoxylate of a pure single-carbon alkanol or an ethoxylate of a
mixture of alkanol homologues with a statistical carbon number
distribution.
[0031] In a second aspect, the present invention provides a process
for manufacturing a concentrate of the first aspect, characterised
in that components (A) to (D) are mixed together at a temperature
in the range of from -10.degree. C. to 60.degree. C., preferably
0.degree. C. to 40.degree. C.
[0032] In a third aspect, the present invention provides a stable
water-in-oil-emulsion, preferably a water-in-oil microemulsion
comprising [0033] (a) a liquid fuel or oil which is immiscible with
water; [0034] (b) up to 1 wt. %, preferably up to 0.1 wt. %, based
on the amount of (a), of water; and [0035] (c) 10 to 10,000 wt.
ppm, preferably 10 to 1,000 wt. ppm, based on the amount of (a), of
a concentrate of the first aspect.
[0036] In a fourth aspect, the present invention provides the use
in a liquid fuel for a turbine engined aircraft of a concentrate of
the first aspect, wherein said liquid fuel is immiscible with
water, characterised in that said use is to scavenge free water
which exists in or is introduced into the said liquid fuel or oil
as a contaminant by forming a stable water-in-oil-emulsion or
water-in-oil-microemulsion, thereby to render or retain the said
liquid fuel or oil in a usable state.
[0037] In a fifth aspect, the present invention provides a method
of scavenging free water which exists in or is introduced as a
contaminant into a liquid fuel which is immiscible with water,
thereby to render or retain the said liquid fuel in a usable state,
which method comprises: adding to a substantially water-free liquid
fuel or to a liquid fuel contaminated with free water a concentrate
of the first aspect in order to form a stable water-in-oil-emulsion
or water-in-oil-microemulsion.
[0038] In each aspect of the present invention, the amounts of
components (A) to (D) preferably add up to 100%.
[0039] The term "free-water" refers to water present as a separate
visible liquid phase in a two phase liquid fuel and water mixture.
This may arise from entrained water or water that is dissolved in
the liquid fuel phase. Dissolved water becomes free water with
lower temperatures due to the reduction in solubility of the water
in liquid fuel.
[0040] In the above aspects of invention, the free-water exists in
or is introduced into the liquid fuel as a contaminant i.e. it is
not water which has been deliberately added to the liquid fuel,
such as water added to a liquid fuel in the preparation of a
water-in-oil emulsion or microemulsion. The free-water exists or is
introduced as a contaminant in the liquid fuel or water when e.g.
water is added to the liquid fuel accidentally or inadvertently, or
the water is ambient moisture such as from rain or condensation
water derived from changes in humidity levels in the atmosphere
whilst the liquid fuel is in a tank vented to atmospheric
conditions or in a tank which is subjected to wide temperature
changes such as that on an aircraft. In the above aspects of the
present invention, the free-water is preferably free-water
introduced into the liquid fuel as ambient moisture. Whilst in
extreme conditions the amount of free-water which may be introduced
as a contaminant could comprise 0.5% by weight or more of the
combined weight of water and liquid fuel, it will be apparent to
those skilled in the art that in practice the amount of free-water
contaminant will typically comprise significantly less than 0.5 wt
% of the combined weight of free-water and liquid fuel. For
example, typically the amount of free-water contaminating the
liquid fuel will be less than 0.2 wt % and more typically less than
0.1 wt %, such as 0.05 wt % or less, by weight of the combined
weight of water and liquid fuel.
[0041] The term "scavenge" means to act as a scavenger and a
"scavenger" is a substance added to a chemical reaction or mixture
to counteract the effect of impurities, as defined in Collins
English Dictionary, Fourth Edition 1998, Reprinted 1999 (twice),
HarperCollins Publishers.
[0042] The terms "liquid fuel" is herein used as substantially
equivalent generic terms for liquids such as jet fuels, aviation
gasolines, military grade fuels, diesels; kerosenes;
gasolines/petrols (leaded or unleaded); paraffinic, naphthenic,
heavy fuel oils, biofuels, waste oils or such as esters, poly alpha
olefins; etc, and mixtures thereof. The liquid fuels most suitable
for practising the present invention are the hydrocarbon fuel oils,
most suitably jet fuel, aviation gasoline, military grade fuels,
biodiesel, bioethanol, diesel, kerosene and gasoline/petrol.
[0043] Preferably the liquid fuel is for a turbine engined aircraft
i.e. a liquid turbine fuel. A liquid turbine fuel is a turbine fuel
customary in civilian or military aviation. These include, for
example, fuels of the designation Jet Fuel A, Jet Fuel A-1, Jet
Fuel B, Jet Fuel JP-4, JP-5, JP-7, JP-8 and JP-8+100. Jet A and Jet
A-1 are commercially available turbine fuel specifications based on
kerosene. The accompanying standards are ASTM D 1655 and DEF STAN
91-91. Jet B is a more highly cut fuel based on naphtha and
kerosene fractions. JP-4 is equivalent to Jet B. JP-5, JP-7, JP-8
and JP-8+100 are military turbine fuels, as used, for example, by
the Marines and Air Force. Some of these standards relate to
formulations which already comprise further additives such as
corrosion inhibitors, other icing inhibitors, static dissipators,
detergents, dispersants, antioxidants, metal deactivators, etc.
[0044] The term "liquid fuel which is immiscible with water" refers
to a liquid fuel, such as a hydrocarbon fuel oil, that is not
miscible with water at greater than about 0.1% water, preferably at
greater than 0.05%, i.e. any admixture of liquid fuel and water
above 0.05% separates out on standing in to two phases.
[0045] The term emulsifying agent, surfactant and
microemulsion-forming surfactant as used herein refers to any
suitable surfactant or mixture of surfactants which is capable upon
simple admixture with a mixture comprising two visible immiscible
phases of a liquid fuel and water of forming a water-in-oil
microemulsion. Formation of the microemulsion is substantially
spontaneous upon the addition at ambient temperature (e.g.
10-30.degree. C.) of the surfactant(s) to a mixture comprising two
visible immiscible phases of a liquid fuel and water. Persons
skilled in the art will be familiar with such surfactants or
surfactant mixtures, for example as disclosed in the microemulsion
prior art references mentioned above. Suitable stable, clear,
water-in-oil microemulsion-forming surfactants are amphoteric or
comprise a mixture of surfactants including at least one amphoteric
betaine. The most preferred surfactants are the emulsifying agents
herein below described.
[0046] Though the physical nature of the clear aqueous compositions
is not fully understood, it is believed that the clear aqueous
compositions comprise an aqueous phase distributed within a
non-aqueous phase, wherein that the aqueous phase is distributed in
the non-aqueous phase in the form of droplets, possibly micelles,
having a size no greater than about 0.1 .mu.m.
[0047] By referring to the microemulsion of the present invention
as being "stable", we mean that the water phase in the water-in-oil
emulsion exists as dispersed droplets having an average particles
size of no greater than 0.1 .mu.m in the oil phase for at least 12
months when stored at a constant temperature of 25.degree. C.
without stirring. The microemulsion is of a continuous fuel phase
in which water droplets, having an average droplet size of no
greater than or <0.1 .mu.m is dispersed. The resultant clear
translucent microemulsion remains thermodynamically stable when
used as a fuel for us in jet or diesel engines. The droplets in the
water-in-oil emulsion of the present invention may be in the form
of micelles.
[0048] It has been found, surprisingly, that when a liquid fuel
containing the relevant surfactants is cooled down below freezing,
very few if any visible ice particles are formed in the fuel and no
gel is formed. As a means to try to explain this very surprising
phenomenon, but without wishing to be limited to this explanation,
it is believed that the presence of the surfactants/emulsifying
agents in the liquid fuel prevents the water from freezing but if
it does not prevent the water from freezing at low temperatures it
restricts the sizes of any ice crystals and agglomerates which may
form in the cooled fuel. Thus, even if ice crystals are formed in
the fuel, the surfactants/emulsifying agents in the fuel prevent
the crystals from significant agglomeration and so no ice slugs are
formed. Further, it is observed that no apple jelly is formed.
DETAILED DESCRIPTION
[0049] Liquid fuel is a hydrocarbon feedstock and can consist of
any of the following: jet fuels, aviation gasolines, military grade
fuels, diesel; kerosene; gasoline/petrol (leaded or unleaded);
paraffinic, naphthenic, heavy fuel oils, biofuels, waste oils or
such as esters, poly alpha olefins; etc, and mixtures thereof.
[0050] The present invention may provide a water content fluid that
due to the inherent stability prevents the formation of ice
particles and apple jelly.
[0051] Prior to the present invention, materials such as diethylene
glycol monomethyl ether (DiEGME) have been used to prevent ice
formation in fuel in small and military aircraft (commercial
airlines tend to use tank heaters). Due to their chemical
properties they are more soluble in water than in fuel and take a
great deal of mixing to get into the fuel. Careful monitoring
during the mixing process must be adhered to at all times to ensure
an initial homogenous fuel. However, no matter how carefully mixed
the DiEGME, (the chemistry is such that it will preferentially
reside in the water phase as temperature reduces) it can separate
from the fuel at low temperatures and enter the water phase. The
DiEGME will prevent some of this water from turning to ice.
However, the DiEGME water mixture has an unusual characteristic in
that it forms a gel like substance often referred to as "apple
jelly" in the aviation industry. Federal Aviation authorities have
attributed several aviation accidents to this material. The present
invention overcomes this problem by, it is believed, preventing the
formation of large ice crystals or ice crystal agglomerates.
Indeed, it is believed that if ice crystals and agglomerates are
formed in the fuel, the size of such particles is restricted to
sub-micron particles (<1 .mu.m). The microemulsion offers
several advantages over the use of DiEGME. The latter tends to be
more hygroscopic in nature and will draw water into a system. The
DiEGME is also chemically aggressive and may attack fuel tank
linings etc, and needs to be used at higher levels than the
emulsifying agents. The handling and disposal of DiEGME is also
costly due to the hazardous nature of the product.
Other than in the operating examples, or where otherwise indicated,
all numbers expressing quantities of ingredients used herein are to
be understood as modified in all instances by the term "about".
[0052] The microemulsion of the present invention may be prepared
from fuels that are standard grades available at any service
station or from industrial suppliers. Preferably, the fuel oil is
selected from jet fuels, aviation gasolines, military grade fuels,
diesel, kerosene, gasoline/petrol (leaded or unleaded) and mixtures
thereof. Preferably the liquid fuel is for a turbine engine
aircraft i.e. a liquid turbine fuel. A liquid turbine fuel is a
turbine fuel customary in civilian or military aviation. These
include, for example, fuels of the designation Jet Fuel A, Jet Fuel
A-1, Jet Fuel B, Jet Fuel JP-4, JP-5, JP-7, JP-8 and JP-8+100. Jet
A and Jet A-1 are commercially available turbine fuel
specifications based on kerosene. The accompanying standards are
ASTM D 1655 and DEF STAN 91-91. Jet B is a more highly cut fuel
based on naphtha and kerosene fractions. JP-4 is equivalent to Jet
B. JP-5, JP-7, JP-8 and JP-8+100 are military turbine fuels, as
used, for example, by the Marines and Air Force. Some of these
standards relate to formulations which already comprise further
additives such as corrosion inhibitors, icing inhibitors, static
dissipators, detergents, dispersants, antioxidants, metal
deactivators, etc. Typical classes and species of such further
additives are disclosed in US 2008/0178523 A1, US 2008/0196300 A1,
US 2009/0065744 A1, WO 2008/107371 and WO 2009/0010441.
[0053] The mixture ratios of the fuel and water employed in the
present emulsion are dependent upon many factors. Generally
speaking, the fuel comprises at least about 99%, preferably at
least about 99.5%, more preferably at least about 99.995%, most
preferably about 99.999% by weight, based on the total weight of
the clear aqueous composition or emulsion. Generally speaking, the
fuel phase comprises no greater than about 99.999% by weight, and
preferably no more than about 99.99% by weight.
[0054] Typically, the composition or microemulsion comprises from
about 0.0001 to about 1.0% by weight of surfactants/emulsifying
agents, preferably from about 0.0001 to about 0.50%, more
preferably from about 0.0001 to about 0.1%, and even more
preferably from about 0.0001 to about 0.025%. The emulsifier is
most preferably a mixture of emulsifying agents selected to
minimise the total amount of emulsifier required to form a
microemulsion for a given fluid.
[0055] Where a compound is referred to as being "ethoxylated", we
mean it includes at least 2 EO groups. Preferably ethoxylated
compounds comprise from 2 to 12 EO groups.
[0056] In a preferred embodiment, the one or more C.sub.6-C.sub.15
alkanol ethoxylates as component (B) have an average degree of
methyl branching for the alkanol unit of 3.7 or less, preferably of
2.5 or less, typically of from 1.5 to 2.5, or, as an alternative,
of 3.7 or less, preferably of 1.5 or less, typically of from 1.05
to 1.0.
[0057] The C.sub.6-C.sub.15 alcohol ethoxylates may have a degree
of methyl branching of at least 2 on the alkanol unit.
[0058] When a mixture of C.sub.6-C.sub.15 alcohol ethoxylates is
employed in the microemulsion, it is preferably a mixture of
C.sub.9-C.sub.14 alcohol ethoxylates, such as a mixture of C.sub.9
to C.sub.11 alcohol ethoxylates or a mixture of C.sub.12-C.sub.14
alcohol ethoxylates. The distribution of any of the components in
the mixture can range from 0 to 50% by weight, and are preferably
distributed in a Gaussian format. Commercially available
C.sub.6-C.sub.15 alcohol ethoxylates include relevant products sold
by leading chemical companies. An example of a commercial
C.sub.12-C.sub.14 alcohol ethoxylate is Lauropal 2 (available from
Witco, England).
[0059] In one embodiment, a concentrate comprises:
(A) 0.1 to 10 wt. % of one or more amphoteric emulsifying agents;
(B) 30 to 95 wt. % of nonionic alkoxylated surfactants; (C) 0 to 20
wt. % of one or more glycol-based solubilizers; and (D) 0 to 65 wt.
% of one or more organic solvents, wherein component (B) comprises
a mixture of C.sub.6-C.sub.15-alkanol ethoxylates with different
carbon numbers for the alkanol unit species, the carbon numbers for
the two C.sub.6-C.sub.15-alkanol ethoxylates which have the highest
share in weight in the mixture being at least 1.5 carbon numbers
distant from each other. Preferably, in the mixture of
C.sub.6-C.sub.15-alkanol ethoxylates, the carbon number for one of
the two C.sub.6-C.sub.15-alkanol ethoxylates which have the highest
share in weight in the mixture are in the range of 9 to 11 for one
and in the range of 12 to 14 for the other. Such mixture preferably
comprises two single-carbon C.sub.6-C.sub.15-alkanol ethoxylates
species in a weight ratio of from 10:90 to 90:10, more preferably
of from 30:70 to 70:30, most preferably of about 50:50. A typical
example of such single-carbon C.sub.6-C.sub.15-alkanol ethoxylates
mixture is a mixture of isodecanol ethoxylate with 3 ethylene oxide
units (commercially available from BASF SE under Lutensol.RTM. ON
30) and tridecanol ethoxylate with 5 ethylene oxide units
(commercially available from BASF SE under Lutensol.RTM. TO 5) in
the weight ratio of 50:50; each of these two alkanol ethoxylate
components exhibits an average degree of methyl branching for the
alkanol unit of 2.2.
[0060] In one embodiment of the present invention, the concentrate
consists essentially of components (A) to (D).
[0061] The emulsifying agents employed in the present invention are
liquids at room temperature.
[0062] The emulsifier composition may also include other materials
such as aliphatic alcohols, glycols and other components which can
be added to a fuel as standard additives.
[0063] In another embodiment, the emulsifying agent comprises the
following: (i) 2 parts cocamidopropyl betaine; (ii) 60 parts
C.sub.9-C.sub.11 alcohol ethoxylate; (iii) 4 parts ethylene glycol
and (iv) 34 parts ethanol
[0064] In one embodiment of the present invention, a microemulsion
is prepared by mixing:
(a) about 99.995 to 99.999 parts, e.g. 99.998 parts, fuel, e.g. a
jet fuel; and (b) about 0.0001 to about 0.01 parts, e.g. 0.025
parts, emulsifying agents, wherein the emulsifying agents include
i) a fatty (C.sub.8-C.sub.24)-amido-(C.sub.1-C.sub.6)alkyl betaine,
ii) a C.sub.6-C.sub.15 alcohol ethoxylate comprising from 2 to 12
EO groups or a mixture of such alcohol ethoxylates, wherein all
parts are by volume.
[0065] The present invention may be utilised in, among others, jet
engines, diesel engines, oil burning heating systems and is suited
to all uses within these application areas. Other uses within the
fuels industry will be apparent to those skilled in the art.
[0066] The microemulsion may comprise additional components. These
additional components may be incorporated to improve anti-wear,
extreme pressure properties, improve cold weather performance or
improve fuel combustion. The requirement to add additional
components may be dictated by the application area in which the
microemulsion is used. Suitable additional components, and the
requirement thereof depending on application area, will be apparent
to those skilled in the art.
[0067] The composition may be added at the wing of the aircraft to
prevent unwanted water pick up during the process of transferring
the fuel from refinery to fuel depot. The composition can be
supplied and intimately mixed with the fuel using a standard fuel
bowser that is currently in operation at any airport. The additive
composition can be dosed at the required rate directly into the
fuel as it is pumped into the aircraft wing using e.g. a venturi
system. This allows intimate mixing to occur and due to the nature
of the composition it readily distributes throughout the fuel and
will remain distributed in the fuel even at temperatures down to as
low as -50.degree. C.
[0068] The present invention will now be further described by way
of example.
EXAMPLES
[0069] Reference hereafter to "a water-in-oil microemulsion wherein
the emulsion is a clear translucent emulsion" is believed to be
analogous to "a water-in-oil microemulsion, wherein the average
droplet size of the water phase of the water-in-oil emulsion is no
greater than 0.25 .mu.m, preferably no greater than 0.1 .mu.m". In
the present examples, the emulsions were visually inspected. Those
which were clear were considered to have an average droplet size of
the water phase of the water-in-oil emulsion of no greater than 0.1
.mu.m.
[0070] In the following examples, all "parts" are parts by weight,
unless stated otherwise.
Example 1
[0071] A concentrate suitable for combining jet fuel (kerosene)
with water was prepared by adding the following components in the
quantities stated:
(i) 97 parts of the Lutensol.RTM. ON 30/Lutensol.RTM. TO 5 mixture
in the weight ratio of 50:50, as disclosed above, and (ii) 3 parts
cocamidopropyl betaine.
[0072] The components were gently mixed to form a homogenous
composition.
Example 2
[0073] A concentrate suitable for combining jet fuel with water was
prepared by adding the following components in the quantities
stated:
i) 1 part by wt cocamidopropyl betaine; (ii) 8 parts by wt of the
Lutensol.RTM. ON 30/Lutensol.RTM. TO 5 mixture in the weight ratio
of 50:50, as disclosed above; (iii) 3 parts by wt C.sub.10 alkyl
amine oxide and iv) 90 parts fatty (C.sub.6-C.sub.24) acid amine
ethoxylates comprising from about 2 to 20 EO groups.
[0074] The components were gently mixed to form a homogenous
composition.
Example 3
[0075] A concentrate suitable for combining jet fuel with water was
prepared by adding the following components in the quantities
stated:
(i) 5 parts by wt cocamidopropyl betaine; (ii) 75 parts by wt of
the Lutensol.RTM. ON 30/Lutensol.RTM. TO 5 mixture in the weight
ratio of 50:50, as disclosed above; (iii) 10 parts by wt C.sub.10
alkyl amine oxide and iv) 10 parts fatty (C.sub.6-C.sub.24) acid
amine ethoxylates comprising from about 2 to 20 EO groups.
[0076] The components were gently mixed to form a homogenous
composition.
Example 4
[0077] A concentrate suitable for combining jet fuel with water was
prepared by adding the following components in the quantities
stated:
(i) 2 parts cocamidopropyl betaine; (ii) 60 parts of the
Lutensol.RTM. ON 30/Lutensol.RTM. TO 5 mixture in the weight ratio
of 50:50, as disclosed above; (iii) 4 parts ethylene glycol and
(iv) 34 parts ethanol
[0078] The components were gently mixed to form a homogenous
composition.
Example 5
[0079] 0.001 l of the concentrate from Example 1 was added to 1 l
of jet fuel (kerosene) contaminated with 200 ppm of water. The
composition was introduced to the oil and water from a micro
pipette. The resulting fluid was gently mixed until a clear
translucent fluid was observed. The resulting fluid remains stable
after more than one year.
Example 6
[0080] 0.001 l of the concentrate from Example 2 was added to 1 l
of jet fuel contaminated with 200 ppm of water. The composition was
introduced to the oil and water from a micro pipette. The resulting
fluid was gently mixed until a clear translucent fluid was
observed. The resulting fluid remains stable after more than one
year.
Example 7
[0081] 0.001 l of the concentrate from Example 3 was added to 1 l
of jet fuel contaminated with 200 ppm of water. The composition was
introduced to the oil and water from a micro pipette. The resulting
fluid was gently mixed until a clear translucent fluid was
observed. The resulting fluid remains stable after more than one
year.
Example 8
[0082] 0.001 l of the concentrate from Example 4 was added to 1 l
of jet fuel contaminated with 200 ppm of water. The composition was
introduced to the oil and water from a micro pipette. The resulting
fluid was gently mixed until a clear translucent fluid was
observed. The resulting fluid remains stable after more than one
year.
Example 9
[0083] The concentrate from Example 4 was subject to differential
scanning calorimetry (DSC) in comparison to current anti icing
product diethylene glycol monomethyl ether (DiEGME) in jet fuel.
The resulting scans showed that the composition performed equally
as well as the DiEGME in the absence of water but in the presence
of 200 ppm water contamination the composition showed no phase
changes indicating no ice formation, whereas the DiEGME showed that
ice was forming due to its poor solubility in fuel allowing free
water particularly at lower temperatures i.e. -40.degree. C.
Example 10
[0084] The concentrate from Example 4 was used to evaluate
microbial growth in aviation fuel. A series of tests based upon the
Speed of Kill and the Persistence of Kill were carried out in
comparison to an untreated water contaminated aviation fuel. In all
cases the composition prevented the growth of microbial content
whereas, the untreated control showed growth up to 10.sup.7 colony
forming units.
[0085] Various modifications and variations of the described
methods and system of the invention will be apparent to those
skilled in the art without departing from the scope and spirit of
the invention. Although the invention has been described in
connection with specific preferred embodiments, it should be
understood that the invention as claimed should not be unduly
limited to such specific embodiments. Indeed, various modifications
of the described modes for carrying out the invention which are
obvious to those skilled in chemistry or related fields are
intended to be within the scope of the following claims.
* * * * *