U.S. patent application number 15/385994 was filed with the patent office on 2018-08-16 for methods of providing higher quality liquid kerosene based-propulsion fuels.
The applicant listed for this patent is SHELL OIL COMPANY. Invention is credited to Joanna Margaret BAULDREAY, Brice Nathaniel DALLY, Cynthia Natalie GINESTRA, Gregory HEMIGHAUS, Anton HUNT.
Application Number | 20180230393 15/385994 |
Document ID | / |
Family ID | 57777734 |
Filed Date | 2018-08-16 |
United States Patent
Application |
20180230393 |
Kind Code |
A1 |
BAULDREAY; Joanna Margaret ;
et al. |
August 16, 2018 |
METHODS OF PROVIDING HIGHER QUALITY LIQUID KEROSENE
BASED-PROPULSION FUELS
Abstract
By blending a quantity of synthetic cyclo-paraffinic kerosene
fuel blending component comprising at least 99.5 mass % of carbon
and hydrogen content and at least 50 mass % of cyclo-paraffin into
kerosene base fuel, kerosene based-propulsion fuels can be upgraded
to higher quality kerosene based-propulsion fuels such as jet fuel
or rocket fuel to meet certain specification and/or increase
volumetric energy content of the propulsion fuel.
Inventors: |
BAULDREAY; Joanna Margaret;
(Manchester, GB) ; DALLY; Brice Nathaniel;
(Madison, WI) ; HEMIGHAUS; Gregory; (Richmond,
CA) ; GINESTRA; Cynthia Natalie; (Houston, TX)
; HUNT; Anton; (Houston, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SHELL OIL COMPANY |
Houston |
TX |
US |
|
|
Family ID: |
57777734 |
Appl. No.: |
15/385994 |
Filed: |
December 21, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62270176 |
Dec 21, 2015 |
|
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|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10L 2270/04 20130101;
C10L 1/1691 20130101; C10L 10/02 20130101; C10L 10/06 20130101;
C10L 2200/043 20130101; C10L 1/04 20130101 |
International
Class: |
C10L 1/16 20060101
C10L001/16; C10L 10/02 20060101 C10L010/02; C10L 1/04 20060101
C10L001/04 |
Claims
1. A method for producing a liquid rocket fuel useful as RP-1 or
RP-2 grade rocket fuels comprising; a. providing a quantity of
kerosene range hydrocarbon component having a boiling point in the
range of 145.degree. C. to 300.degree. C., at atmospheric pressure,
flash point of at least 60.degree. C. or above measured by ASTM
D56, a density at 15.degree. C. of at most 815 kg/m.sup.3; b.
providing a quantity of synthetic cyclo-paraffinic kerosene fuel
blending component comprising component comprising at least 99.5
mass % of carbon and hydrogen content and at least 50 mass % of
cyclo-paraffin, said cyclo-paraffinic kerosene fuel blending
component having a boiling point of at most 300.degree. C., at
atmospheric pressure, flash point of at least 38.degree. C.,
preferably at least 45.degree. C., preferably at least 50.degree.
C., more preferably at least 55.degree. C., more preferably at
least 60.degree. C. a density at 15.degree. C. of at least 799
kg/m.sup.3, and freezing point of -60.degree. C. or lower; and c.
blending a quantity of the synthetic cyclo-paraffinic kerosene fuel
blending component and the kerosene range hydrocarbon component in
amount sufficient to meet a flash point of at least 60.degree. C.
and final boiling point of 274.degree. C. or lower to produce the
blended liquid rocket fuel.
2. The method of claim 1 wherein the freezing point of the blended
rocket fuel is -51.degree. C. or lower.
3. The method of claim 1 wherein the blended rocket fuel have a
density in the range of 799 to 815 kg/m.sup.3 at 15.degree. C.
4. The method of claim 1 wherein the rocket fuel blend has a
-34.degree. C. kinematic viscosity (measured according to ASTM D445
method) that is less than 10 cSt.
5. The method of claim 1 wherein the blended rocket fuel has a
volumetric energy density in the range of 34,380 to 35,070
MJ/m.sup.3.
6. The method of claim 1 wherein the hydrogen content is at least
13.8 mass %.
7. The method of claim 1 wherein the net heat of combustion is at
least 43.03 MJ/kg.
8. The method of claim 1 wherein the sulfur content of the
synthetic cyclo-paraffinic kerosene fuel blending component is no
more than 0.0030 mass %.
9. The method of claim 1 wherein the sulfur content of the blended
liquid rocket fuel is no more than 0.0030 mass %.
10. The method of claim 1 wherein the liquid rocket fuel is blended
to meet a thermal stability requirement at a temperature of at
least 355.degree. C.
11. The method of claim 1 wherein the cyclo-paraffinic kerosene
fuel blending component has a boiling point of 290.degree. C. or
below.
12. The method of claim 1 wherein the cyclo-paraffinic kerosene
fuel component is bio-based.
13. The method of claim 1 wherein the amount of cyclo-paaffinie
kerosene fuel blending component in the liquid rocket fuel is at
least 1 vol. %.
14. The method of claim 13 wherein the amount of cyclo-paraffinie
kerosene fuel blending component in the liquid rocket fuel is at
least 3 vol. %
15. A liquid rocket fuel comprising a cyclo-paraffinic kerosene
fuel blending component produced according to any of the methods of
claim 1.
16. A liquid rocket fuel comprising a cyclo-paraffinic kerosene
fuel blending component produced according to any of the methods of
claim 4.
17. A liquid rocket fuel comprising a cyclo-paraffinic kerosene
fuel blending component produced according to any of the methods of
claim 13.
18. A liquid rocket fuel comprising a cyclo-paraffinic kerosene
fuel blending component produced according to any of the methods of
claim 14.
19. A liquid rocket fuel having a flash point of at least
60.degree. C. and final boiling point of 274.degree. C. or lower
comprising a blended fuel comprising a quantity of kerosene range
hydrocarbon component having a boiling point in the range of
145.degree. C. to 300.degree. C., at atmospheric pressure, flash
point of at least 60.degree. C. or above measured by ASTM D56, a
density at 15.degree. C. of at most 815 kg/m.sup.3; a quantity of
synthetic cyclo-paraffinic kerosene fuel blending component
comprising component comprising at least 99.5 mass % of carbon and
hydrogen content and at least 50 mass % of cyclo-paraffin, said
cyclo-paraffinic kerosene fuel blending component having a boiling
point of at most 300.degree. C., at atmospheric pressure, flash
point of at least 38.degree. C., preferably at least 45.degree. C.,
preferably at least 50.degree. C., more preferably at least
55.degree. C., more preferably at least 60.degree. C. a density at
15.degree. C. of at least 799 kg/m.sup.3, and freezing point of
-60.degree. C. or lower.
20. The liquid rocket fuel of claim 19 wherein the liquid rocket
fuel has a -34.degree. C. kinematic viscosity (measured according
to ASTM D445 method) that is less than 10 cSt.
21. The liquid rocket fuel of claim 20 wherein the liquid rocket
fuel has a -34.degree. C. kinematic viscosity (measured according
to ASTM D445 method) that is less than 9 cSt.
22. The liquid rocket fuel of claim 20 wherein the liquid rocket
fuel has a -34.degree. C. kinematic viscosity (measured according
to ASTM D445 method) that is less than 8 cSt.
Description
[0001] The present application claims the benefit of pending U.S.
Provisional Application Ser. No. 62/270,176, filed 21 Dec. 2015,
the entire disclosure of which is hereby incorporated by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to methods of providing higher
quality kerosene-based propulsion fuels.
BACKGROUND OF THE INVENTION
[0003] Typical jet fuels and liquid kerosene rocket fuels are
prepared in a refinery from a crude mineral oil source. Typically
the crude mineral oil is separated by means of distillation into a
distillate kerosene fraction boiling in the aviation fuel range or
a more purified liquid kerosene rocket fuel. If required, these
fractions are subjected to hydroprocessing to reduce sulfur,
oxygen, and nitrogen levels.
[0004] Increasing demand for jet fuel and the environmental impact
of aviation related emissions places the aviation industry at the
forefront of today's global energy challenge. The increased demand
for petroleum-based fuels has resulted in a higher production of
greenhouse gases. In particular, the aviation industry accounts for
about 2% of global CO.sub.2 emissions. The aviation transport
sector is growing 3-5% year on year, and due to the projected
increasing demand for fuel and increasing production of CO.sub.2
emissions, there is a need to explore methods to increase
environmentally-friendly fuel sources while meeting jet fuel
specifications.
[0005] Perhaps more tangible than the global impact of greenhouse
gases is the impact of local emissions from aircraft. Emissions
near and around airports have a direct impact on the air
composition and therefore have been linked with poor local air
quality, which can be further linked to impacts on human health.
Sooty particulates and oxides of sulfur and nitrogen are considered
to be contributors to poor local air quality. Thus, local air
quality is seen as an integral element in the pursuit of
environment-friendly fuels.
[0006] Petroleum-derived jet fuels inherently contain both
paraffinic and aromatic hydrocarbons. In general, paraffinic
hydrocarbons offer the most desirable combustion cleanliness
characteristics for jet fuels. Aromatics generally have the least
desirable combustion characteristics for aircraft turbine fuel. In
aircraft turbines, certain aromatics, such as naphthalenes, tend to
burn with a smokier flames and release a greater proportion of
their chemical energy as undesirable thermal radiation than other
more saturated hydrocarbons.
[0007] The closest current option for reducing aviation emissions
is blending synthesized paraffinic kerosene ("SPK") from
Fischer-Tropsch or hydrogenated vegetable oil with conventional jet
fuel. Up to 50% by volume of SPK is permitted by the alternative
jet fuel specification ASTM D7566. If the resulting blend meets the
specification, it can be certified and considered equivalent to
conventional, petroleum-derived jet fuel. Typically, these
synthesized paraffinic kerosenes contain a mixture of normal and
branched paraffin according to ASTM D7566.
[0008] It is important that novel fuels meet their respective jet
fuel specifications without having a detrimental impact on safety
or aircraft performance. Because SPK is purely paraffinic and
absent of both aromatics and sulfur, it does not exhibit all of the
desired properties expected from a jet fuel. For example, a gas to
liquids Fischer-Tropsch-derived fuel is not considered an on-spec
fuel in its pure state due to its lower density. Further, SPK fuels
tend to have low volumetric energy density, which may require more
fuel than can be accommodated in aircraft fuel tanks for long
distance flights.
[0009] Kerosene fuels can also be used as liquid rocket fuels.
MIL-DTL-25576 defines two grades of kerosene fuels, rocket
propellant (RP) fuels known as RP-1 and RP-2, for use in rocket
engines. These fuels, while still kerosene-type fuels, have some
different property requirements from jet fuels. RP fuels have a
higher minimum flash point at 60.degree. C., a lower maximum
freezing point at -51.degree. C., higher temperature thermal
stability requirement at 355.degree. C., lower maximum total
aromatics content of 5% volume, and reduced density range of
799-815 kg/m.sup.3 at 15.degree. C., and reduced distillation
range, with T10 between 185.degree. C. and 210.degree. C. and
maximum distillation end point of 274.degree. C.
SUMMARY OF THE INVENTION
[0010] In accordance with certain of its aspects, provided is a
method for producing a liquid rocket fuel useful as RP-1 or RP-2
grade rocket fuels comprising;
[0011] a. providing a quantity of kerosene range hydrocarbon
component having a boiling point in the range of 145.degree. C. to
300.degree. C., at atmospheric pressure, flash point of at least
60.degree. C. or above measured by ASTM D56, a density at
15.degree. C. of at most 815 kg/m.sup.3;
[0012] b. providing a quantity of synthetic cyclo-paraffinic
kerosene fuel blending component comprising component comprising at
least 99.5 mass % of carbon and hydrogen content and at least 50
mass % of cyclo-paraffin, said cyclo-paraffinic kerosene fuel
blending component having a boiling point of at most 300.degree.
C., at atmospheric pressure, flash point of at least 38.degree. C.,
a density at 15.degree. C. of at least 799 kg/m.sup.3, and freezing
point of -60.degree. C. or lower; and
[0013] c. blending a quantity of the synthetic cyclo-paraffinic
kerosene fuel blending component and the kerosene range hydrocarbon
component in amount sufficient to meet a flash point of at least
60.degree. C. and final boiling point of 274.degree. C. or lower to
produce the blended liquid rocket fuel.
[0014] The features and advantages of the invention will be
apparent to those skilled in the art. While numerous changes may be
made by those skilled in the art, such changes are within the
spirit of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] The drawings illustrate certain aspects of some of the
embodiments of the invention, and should not be used to limit or
define the invention.
[0016] FIG. 1 shows the volumetric energy density (MJ/m.sup.3) of
the jet fuel blends based on paraffinic kerosene content (vol. %)
in Jet A of various fuels from Examples described herein.
[0017] FIG. 2 shows a plot of the aromatics content (vol. %) versus
volumetric energy density (MJ/m.sup.3) of the various jet fuel
blends from Examples described herein.
[0018] FIG. 3 shows the smoke point increase of jet fuel with
volumetric energy density (MJ/m.sup.3) of the various jet fuel
blends from Examples described herein.
[0019] FIG. 4 shows the freezing point (.degree. C.) of various jet
fuel blends from Examples described herein versus volumetric energy
density (MJ/m.sup.3).
[0020] FIG. 5 shows the comparison of sub-zero viscosities of
commercial RP rocket fuels versus the rocket fuel of the invention
from Example 6.
DETAILED DESCRIPTION OF THE INVENTION
[0021] It has been found that by blending a quantity of certain
synthetic cyclo-paraffinic kerosene fuel blending components
comprising at least 99.5 mass % of carbon and hydrogen content and
at least 50 mass % of cyclo-paraffin into a kerosene base fuel, the
fuel can be upgraded or blended to meet certain specifications
and/or increase its volumetric energy content for jet and rocket
fuel applications. More specifically, it has been found that by
blending a quantity of the certain synthetic cyclo-paraffinic
kerosene fuel blending components into certain kerosene base fuel
or a kerosene range hydrocarbon component, a fuel useful as a
liquid rocket fuel (such as RP-1 or RP-2 grade rocket fuels) may be
produced.
[0022] Such liquid rocket fuel may be produced by:
[0023] a. providing a quantity of kerosene range hydrocarbon
component having a boiling point in the range of 145.degree. C. to
300.degree. C., at atmospheric pressure, flash point of at least
60.degree. C. or above measured by ASTM D56, a density at
15.degree. C. of at most 815 kg/m.sup.3;
[0024] b. providing a quantity of synthetic cyclo-paraffinic
kerosene fuel blending component comprising component comprising at
least 99.5 mass % of carbon and hydrogen content and at least 50
mass % of cyclo-paraffin, said cyclo-paraffinic kerosene fuel
blending component having a boiling point of at most 300.degree.
C., at atmospheric pressure, flash point of at least 38.degree. C.,
a density at 15.degree. C. of at least 799 kg/m.sup.3, and freezing
point of -60.degree. C. or lower; and
[0025] c. blending a quantity of the synthetic cyclo-paraffinic
kerosene fuel blending component and the kerosene range hydrocarbon
component in amount sufficient to meet a flash point of at least
60.degree. C. and final boiling point of 274.degree. C. or lower to
produce the blended liquid rocket fuel.
[0026] In one embodiment, it has also been found that the
volumetric energy content of a fuel can be increased without
increase in its aromatic content by:
[0027] a. providing a quantity of kerosene base fuel having a
boiling point in the range of 130.degree. C. to 300.degree. C., at
atmospheric pressure, flash point of 38.degree. C. or above
measured by ASTM D56, and a density at 15.degree. C. of at least
760 kg/m.sup.3, preferably at least 770 kg/m.sup.3;
[0028] b. providing a quantity of a synthetic cyclo-paraffinic
kerosene fuel blending component comprising at least 99.5 mass % of
carbon and hydrogen content and at least 50 mass % of
cyclo-paraffin, said cyclo-paraffinic kerosene fuel blending
component having a boiling point of at most 300.degree. C., at
atmospheric pressure, flash point of 38.degree. C. or above, a
density at 15.degree. C. of at least 800 kg/m.sup.3, and freezing
point of -60.degree. C. or lower; and
[0029] c. blending a quantity of the synthetic cyclo-paraffinic
kerosene fuel blending component to the kerosene base fuel in
amount effective to increase the volumetric energy content,
preferably at least 0.1% increase in the volumetric energy
content.
[0030] Volumetric energy content can be calculated as energy per
unit volume using the following equation:
Energy per unit volume (MJ/m.sup.3)=(energy per unit mass
(MJ/kg))*(density (kg/m.sup.3))
Energy per unit mass can be obtained by one of several methods,
including ASTM D4529, D3338, D4809, or IP12 by way of example. The
increase in volumetric energy content is relative so any of these
methods can be used as long as the same method is used.
[0031] As used herein, "lower" in context of freezing points (e.g.,
the term "X.degree. C. or lower") means that the temperature is
equal to or lower than the X temperature. For example, for a
freezing point of "-60.degree. C. or lower", the temperature may
be, for example, -60.degree. C., -61.degree. C., -65.degree. C.,
-70.degree. C., etc., as long as the temperature is not higher than
-60.degree. C.
[0032] In certain embodiments, the kerosene-based fuel component
may originate from petroleum or be synthetically derived from
biomass or other non-biomass resources. Aromatics content in a jet
fuel can be determined by ASTM D1319. Aromatics content for
synthetic blend components can be determined by ASTM D2425. The
aromatic content of the blended jet fuel is typically determined by
ASTM D1319. Equivalent total aromatic content between two fuels
means the total aromatic content measured by these methods give an
aromatic content within +/-1.5 vol. %. Minimal increase of aromatic
content is generally less than 3 vol. %, preferably less than 2
vol. %, more preferably less than 1.5 vol. %, or more preferably
without an increase that is within the precision of measurement for
aromatic content, or even a decrease in aromatic content.
[0033] The method above may also produce a fuel having an improved
smoke point as compared with the kerosene base fuel component
without the cyclo-paraffinic kerosene fuel blending component. In
an embodiment, the smoke point is at least 1 mm greater than the
kerosene base fuel as measured by ASTM D1322.
[0034] ASTM International ("ASTM") and the United Kingdom Ministry
of Defence ("MOD") have taken the lead roles in setting and
maintaining specification for civilian aviation turbine fuel and
jet fuel. The respective specifications issued by these two
organizations are very similar, but not identical. Many other
countries issue their own national specifications for jet fuel, but
are very nearly or completely identical to either the ASTM or MOD
specification. ASTM D1655 is the Standard Specification for
Aviation Turbine Fuels and includes specifications for Jet A and
Jet A-1. Defense Standard 91-91 is the MOD specification for Jet
A-1 and is the dominant fuel specification for Jet A-1 outside of
the United States.
[0035] Jet A-1 is the most common jet fuel and is produced to an
internationally standardized set of specifications. In the United
States, Jet A is the primary grade of jet fuel. Another jet fuel
that is used in civilian aviation is called Jet B. Jet B is a
wide-cut, lighter fuel in the naphtha-kerosene region that is used
for its enhanced cold-weather performance Jet A and Jet A-1 are
specified in ASTM D1655. Jet B is specified in ASTM D6615.
[0036] Alternatively, jet fuels are classified by militaries around
the world with a different system of NATO or JP (Jet Propulsion)
numbers. Some are almost identical to their civilian counterparts
and differ only by the amounts of a few additives. For example, Jet
A-1 is similar to JP-8. Both Jet A-1 and JP-8 specifications
require a freezing point of -47.degree. C. or lower. Jet A
specification requires a freezing point of -40.degree. C. or lower
as does the military equivalent F-24. Jet B is similar to JP-4 that
requires a freezing point of -58.degree. C. or lower. Other jet
fuel specifications for militaries may include JP-5 that requires a
freezing point of -46.degree. C. or lower and JP-7 that requires a
freezing point of -43.3.degree. C. or lower and the RP grades that
requires a freezing point of -51.degree. C. or lower.
[0037] Further, some jet fuel specifications have more stringent
requirement for flight in more challenging environments. For cold
climates, such as the Antarctic, AN-8 has a jet fuel specification
with a freezing point of -58.degree. C. or lower. AN-8 fuel is used
for turbine engines and other power applications that require low
freeze point for low temperature applications and storage.
[0038] Typically, jet fuel is a product boiling for more than 90
vol. % at from 130.degree. C. to 300.degree. C. (ASTM D86), having
a density in the range from 775 to 840 kg/m.sup.3, preferably from
780 to 830 kg/m.sup.3, at 15.degree. C. (e.g. ASTM D4052), an
initial boiling point in the range 130.degree. C. to 190.degree. C.
and a final boiling point in the range 220.degree. C. to
300.degree. C., at atmospheric pressure, a flash point of
38.degree. C. or above (ASTM D56), a kinematic viscosity at
-20.degree. C. (ASTM D445) suitably from 1.2 to 8.0 mm.sup.2/s and
a freeze point of -40.degree. C. or below for Jet A specification,
preferably -47.degree. C. or below for Jet A-1 and JP-8
specifications, and preferably -58.degree. C. or below for AN-8
specification.
[0039] Jet fuel will typically meet one or more of the following
civil standards. Jet A-1 requirements are in ASTM D1655 or DEF STAN
91-91 (British Ministry of Defence Standard DEF STAN 91-91/Issue 7
amendment 3 of 2 Feb. 2015 (or later issues) for Turbine Fuel,
Aviation "Kerosene Type," Jet A-1, NATO code F-35, Joint Service
Designation AVTUR, or versions current at the time of testing), as
well as some airport handling requirements of the IATA Guidance
Material for Aviation Turbine Fuels Specifications. Jet A
requirements are in ASTM D1655. Military jet fuel requirements are
similar to civil requirements but usually more stringent for select
properties and in the use of additives; these requirements are
published by respective governments. For example, these can include
MIL-DTL-83133 which defines JP-8 as used by US federal
agencies.
[0040] Due to the differences in the specifications and depending
on locations and intended use, it is desirable to upgrade the fuel
to achieve the specification that the fuel must meet in order to
fly in certain regions. For example, it may be desirable to upgrade
a jet fuel which meets the Jet A specification to a fuel that has a
lower freezing point consistent with the Jet A-1 specification
requirement, particularly without an increase in its aromatic
content. In another example, it may be desirable to upgrade a jet
fuel to a cold climate specification, such as AN-8 jet fuel
specification, which requires an even lower freezing point.
[0041] It has been found that by blending a quantity of synthetic
cyclo-paraffinic kerosene fuel blending component comprising at
least 99.5 mass % of carbon and hydrogen content and at least 50
mass % of cyclo-paraffin, the cyclo-paraffinic kerosene fuel
blending component having a boiling point of at most 300.degree.
C., at atmospheric pressure, flash point of 38.degree. C. or above,
and a density at 15.degree. C. of at least 800 kg/m.sup.3, and
freezing point of -60.degree. C. or below, one can upgrade a
kerosene base fuel to meet certain specifications.
[0042] As used herein, upgrading to meet a fuel specification means
blending a fuel that does not meet the specification standard, to
meeting the standard for such fuel specification. For jet fuels, it
is particularly desirable to upgrade the jet fuel without
increasing its aromatic content. To meet a jet fuel specification
property means that the jet fuel meets the requirements of at least
one of the above mentioned specifications, as determined by
standard test methods, such as from ASTM, IP, or other such
industry-recognized standards bodies. Test methods for determining
if a fuel meets a specification may include:
TABLE-US-00001 TABLE 1 Test for Jet Fuel Specification Properties
Test ASTM Method Acidity (mgKOH/g) D3242 Density at 15.degree. C.
(g/cm.sup.3) D4052 Hydrogen Content (mass %) D7171 Flash Point
(.degree. C.) D56 Freeze Point (.degree. C.) D5972 Viscosity
(mm.sup.2/s) D445 Total Sulfur (mass %) D4294 Mercaptan sulfur
(mass %) D3227 Smoke Point (mm) D1322 Naphthalenes (vol. %) D1840
Aromatics (vol. %) D1319 Net Heat of Combustion (MJ/kg) D3338
Initial Boiling Point (IBP) (.degree. C.) D86 Final Boiling Point
(FBP) (.degree. C.) D86
[0043] It is desirable to produce a quality liquid rocket fuel that
meets the rocket fuel specifications. MIL-DTL-25576E specifies 2
grades of rocket fuel, RP-1 and RP-2, which are identical except
for the maximum sulfur content. RP-1 has a maximum allowable sulfur
content of 0.0030 mass %, while RP-2 has a maximum allowable sulfur
content of 0.00001 mass %. Both RP-1 and RP-2 have a maximum
aromatics content of 5 vol. %, a 10% distillation point between
185.degree. C. and 210.degree. C., a distillation end point maximum
of 274.degree. C., a minimum flash point of 60.degree. C., a
density range at 15.degree. C. of 799-815 kg/m.sup.3, a maximum
freezing point of -51.degree. C., a minimum hydrogen content of
13.8 mass %, and a thermal stability test temperature of
355.degree. C.
Kerosene Base Fuel or Kerosene Range Hydrocarbon Component
[0044] A kerosene base fuel or kerosene range hydrocarbon component
is any kerosene that may be useful as a jet or rocket fuel, or a
jet or rocket fuel blending component (other than the synthetic
cyclo-paraffinic kerosene fuel blending component described herein)
having a boiling point in the range of 130.degree. C. to
300.degree. C., at atmospheric pressure (as measured by ASTM D86),
preferably in the range of 140.degree. C. to 300.degree. C., and
most preferably in the range of 145.degree. C. to 300.degree. C.
For a jet fuel blending component, the kerosene base fuel (whether
single stream or a mixture) can have a flash point of 38.degree. C.
or above (measured by ASTM D56), and a density at 15.degree. C. of
at least 760 kg/m.sup.3 (as measured by D4052). For liquid rocket
fuel, the kerosene range hydrocarbon component can have a boiling
point in the range of 145.degree. C. to 300.degree. C., preferably
in the range of 145.degree. C. to 270.degree. C.; a flash point of
60.degree. C. or above, measured by ASTM D56; and a density at
15.degree. C. of at most 815 kg/m.sup.3. The kerosene base fuel or
kerosene range hydrocarbon component may originate from petroleum
or be synthetically derived from biomass, or other non-biomass
resources. In certain embodiments, the kerosene base fuel may be
any petroleum-derived jet fuel known to skilled artisans, including
kerosene fuels meeting at least one of Jet A, Jet A-1, F-24, JP-8,
Jet B or AN-8 specification. Preferably, the kerosene base fuel is
a kerosene that can meet the jet fuel specification properties
according to the invention.
[0045] For example, petroleum-derived kerosene fuels meeting Jet A
or Jet A-1 requirements and a kerosene stream used in Jet A or Jet
A-1 production are listed in Table 2. It is also contemplated that
petroleum-derived kerosene fuels which do not meet Jet A or Jet A-1
specifications may be used as kerosene base fuels that can be
upgraded to meet such specifications according to the present
invention.
TABLE-US-00002 TABLE 2 Jet Fuel Produced Using: Straight run
kerosene stream. Caustic washing of straight run kerosene. A
sweetening process such as Merox .RTM., Merichem .RTM., or Bender
process. Hydroprocessed jet fuel.
[0046] As another example, the low boiling fraction as separated
from a mineral gas oil may be used as such or in combination with
petroleum-derived kerosene, suitably made at the same production
location. As the low boiling fraction may already comply with a jet
fuel specification, it is evident that the blending ratio between
said component and the petroleum-derived kerosene may be freely
chosen. The petroleum-derived kerosene will typically boil for more
than 90 vol. % within the usual kerosene range of 145.degree. C. to
300.degree. C. (ASTM D86), depending on grade and use. It will
typically have an initial boiling point in the range 130.degree. C.
to 190.degree. C., and a final boiling point in the range
220.degree. C. to 300.degree. C. It will typically have a density
from 775 to 840 kg/m.sup.3 at 15.degree. C. (e.g., ASTM D4052 or IP
365). Its kinematic viscosity at -20.degree. C. (ASTM D445) might
suitably be from 1.2 to 8.0 mm.sup.2/s.
[0047] The kerosene base fuel or kerosene range hydrocarbon
component may be a straight run kerosene fraction as isolated by
distillation from a crude oil source or a kerosene fraction
isolated from the effluent of typical refinery conversion
processes, preferably hydrocracking. The kerosene fraction may also
be the blend of straight run kerosene and kerosene as obtained in a
hydrocracking process. Suitably the properties of the mineral
derived kerosene are those of the desired jet fuel as defined
above.
[0048] Aromatic content of the kerosene base fuel may vary in the
range of 0 to 25 vol. %, preferably 3 to 25 vol. %, more preferably
15 to 20 vol. % based on the fuel (as measured by ASTM 1319).
Typical density of the petroleum-derived kerosene at 15.degree. C.
is in the range of 775 kg/m.sup.3 to 840 kg/m.sup.3 (as measured by
D4052). The kerosene base fuel most useful for the inventive
process may have a density of at least 760 kg/m.sup.3, more
preferably at least 775 kg/m.sup.3, to preferably at most 840
kg/m.sup.3, and more preferably at most 820 kg/m.sup.3. The
aromatic content of the kerosene range hydrocarbon component for
liquid rocket fuel may vary in the range of 0 to 10 vol. %,
preferably 0 to 5 vol. %.
[0049] The kerosene base fuel may be a single stream from a
refining stream (petroleum-derived kerosene), or a mixture of one
or more refining streams, or a mixture of refining streams and one
or more synthetic kerosene components, or one or more synthetic
kerosene streams (other than the synthetic cyclo-paraffinic
blending component) approved by ASTM D7566 or equivalent
specifications.
[0050] For Example, kerosene range hydrocarbon component may be
aliphatic mineral spirits having flash points in the range of
60.degree. C. up to 120.degree. C., preferably 63.degree. C. up to
120.degree. C. Preferably, the aliphatic mineral spirits also have
density at 15.degree. C. from 790 to 820 kg/m.sup.3. These
aliphatic mineral spirits are typically mixtures of normal-, iso-
and cyclo-paraffins. Aliphatic mineral spirits are fractionated
from selected feedstock. Their low aromatics content is obtained by
deep hydrogenation. Commercially available kerosene range
hydrocarbon component may include ShellSol.TM. D (de-aromatised)
grades available from Shell Chemical Co. such as for example,
ShellSol D60, D70, D80, D90 and D100 or suitably fractionated
aliphatic mineral spirits having flash points in the appropriate
range. Other aliphatic mineral spirits such as Isopar.TM.
isoparaffinic fluids or NORPAR.TM. fluids may be used. Kerosene
range hydrocarbon component may also be kerosene base fuel so long
as it can meet the kerosene range hydrocarbon component properties
and the final blend can meet the rocket fuel specifications.
Synthetic Cyclo-paraffinic Kerosene Fuel Blending Component
[0051] The synthetic cyclo-paraffinic kerosene fuel blending
component is generally characterized as a liquid composed of
individual hydrocarbons useable as a jet fuel blending component
and having at least the following properties: comprising at least
99.5 mass % of carbon and hydrogen content and at least 50 mass %
of cyclo-paraffin.
[0052] For jet fuel applications, the cyclo-paraffinic kerosene
fuel blending component can typically have a boiling point of at
most 300.degree. C., at atmospheric pressure; flash point of
38.degree. C., or above; a density at 15.degree. C. of at least 800
kg/m.sup.3, preferably at least 810 kg/m.sup.3, preferably at most
845 kg/m.sup.3, more preferably at most 830 kg/m.sup.3, most
preferably in the range of 810 to 818 kg/m.sup.3; and a freezing
point of -60.degree. C. or below, preferably of -65.degree. C. or
below, more preferably of -70.degree. C. or below.
[0053] For rocket fuel applications, preferably the synthetic
cyclo-paraffinic kerosene fuel blending component is generally
characterized as a liquid composed of individual hydrocarbons
useable as a rocket fuel blending component and having at least the
following properties: comprising at least 99.5 mass % of carbon and
hydrogen content and at least 50 mass % of cyclo-paraffin. The
cyclo-paraffinic kerosene fuel blending component can typically
have a flash point of at least 38.degree. C., preferably at least
45.degree. C., preferably at least 50.degree. C., more preferably
at least 55.degree. C., more preferably at least 60.degree. C.; a
density at 15.degree. C. of at least 799 kg/m.sup.3; and a freezing
point of -60.degree. C. or lower, preferably of -65.degree. C. or
lower, more preferably of -70.degree. C. or lower. Further, the
cyclo-paraffinic kerosene fuel blending component can have good
thermal stability for use in rocket fuel. The cyclo-paraffinic
kerosene fuel blending component typically has a final boiling
point below 300.degree. C., more preferably below 290.degree. C.,
more preferably below 280.degree. C., most preferably below
274.degree. C.
[0054] The synthetic cyclo--paraffinic kerosene fuel blending
component preferably has a maximum iso-paraffin and n-paraffin
content of less than 50 mass %, preferably less than 40 mass %,
less than 35 mass %, or less than 30 mass % (ASTM D2425 or
optionally can be measured by GCxGC). The synthetic
cyclo-paraffinic kerosene fuel blending component preferably has at
least 60 mass %, at least 65 mass %, or at least 70 mass % of
cyclo-paraffinic content (ASTM D2425 or optionally can be measured
by GCxGC). The aromatic content of the synthetic cyclo-paraffinic
kerosene fuel blending component is preferably at most L5 mass %,
at most 1 mass %, or at most 0.5 mass %. (ASTM D2425 or optionally
can be measured by GCxGC).
[0055] In certain embodiments, the synthetic cyclo-paraffinic
kerosene fuel blending component is derived from biomass
(bio-derived cyclo-paraffinic kerosene fuel blending component). As
used herein, the term "biomass" refers to, without limitation,
organic materials produced by plants (such as leaves, roots, seeds
and stalks), and microbial and animal metabolic wastes. Common
biomass sources include: (1) agricultural residues, including corn
stover, straw, seed hulls, sugarcane leavings, bagasse, nutshells,
cotton gin trash, and manure from cattle, poultry, and hogs; (2)
wood materials, including wood or bark, sawdust, timber slash, and
mill scrap; (3) municipal solid waste, including recycled paper,
waste paper and yard clippings; and (4) energy crops, including
poplars, willows, switch grass, miscanthus, sorghum, alfalfa,
prairie bluestream, corn, soybean, and the like. The term also
refers to the primary building blocks of the above, namely, lignin,
cellulose, hemicellulose and carbohydrates, such as saccharides,
sugars and starches, among others.
[0056] Common biomass-derived feedstocks include lignin and
lignocellulosic derivatives, cellulose and cellulosic derivatives,
hemicellulose and hemicellulosic derivatives, carbohydrates,
starches, monosaccharides, disaccharides, polysaccharides, sugars,
sugar alcohols, alditols, polyols, and mixtures thereof.
Preferably, the biomass-derived feedstock is derived from material
of recent biological origin such that the age of the compounds, or
fractions containing the compounds, is less than 100 years old,
preferably less than 40 years old, and more preferably less than 20
years old, as calculated from the carbon 14 concentration of the
feedstock.
[0057] The biomass-derived feedstocks may be derived from biomass
using any known method. Solvent-based applications are well known
in the art. Organosolv processes use organic solvents such as ionic
liquids, acetone, ethanol, 4-methyl-2-pentanone, and solvent
mixtures, to fractionate lignocellulosic biomass into cellulose,
hemicellulose, and lignin streams (Paszner 1984; Muurinen 2000; and
Bozell 1998). Strong-acid processes use concentrated hydrochloric
acid, phosphoric acid, sulfuric acid or other strong organic acids
as the depolymerization agent, while weak acid processes involve
the use of dilute strong acids, acetic acid, oxalic acid,
hydrofluoric acid, or other weak acids as the solvent. Enzymatic
processes have also recently gained prominence and include the use
of enzymes as a biocatalyst to deconstruct the structure of the
biomass and allow further hydrolysis to useable feedstocks. Other
methods include fermentation technologies using microorganisms,
Fischer-Tropsch reactions and pyrolysis technologies, among
others.
[0058] In one embodiment, the synthetic cyclo-paraffinic kerosene
fuel blending component is derived from the conversion of a
biomass-derived feedstock containing one or more carbohydrates,
such as starch, monosaccharides, disaccharides, polysaccharides,
sugars, and sugar alcohols, or derivatives from lignin,
hemicellulose and cellulose using a bioreforming processes. As used
herein, the term "bioreforming" refers to, without limitation,
processes for catalytically converting biomass-derived oxygenated
hydrocarbons to lower molecular weight hydrocarbons and oxygenated
compounds using aqueous phase reforming, hydrogenation,
hydrogenolysis, hydrodeoxygenation and/or other conversion
processes involving the use of heterogeneous catalysts. Examples of
various bioreforming processes include those technologies described
in U.S. Pat. Nos. 8,053,615, 8,017,818 and 7,977,517 (all to
Cortright and Blommel, and entitled "Synthesis of Liquid Fuels and
Chemicals from Oxygenated Hydrocarbons"); U.S. Pat. No. 8,642,813
(to Qiao et al., and entitled "Reductive Biomass Liquefaction");
U.S. Patent Application Publication No. 2012/0198760 (to Blommel et
al., and entitled Methods and Systems for Making Distillate Fuels
from Biomass); and U.S. Patent Application Publication No.
2013/0263498 (to Kania et al., and entitled Production of
Distillate Fuels from Biomass-Derived Polyoxygenates); and U.S.
Patent Application Pub. No. 2013/0036660 (to Woods et al. and
entitled "Production of Chemicals and Fuels from Biomass"), all of
which are incorporated herein by reference.
[0059] Alternatively, the synthetic cyclo-paraffinic kerosene fuel
blending component may be produced using natural gas or
syngas-derived feedstocks used in a bioreforming process. For
example, certain alkanols and other mixed oxygenated hydrocarbons
derived from natural gas or syngas using Fischer-Tropsch type
reactions may have application in the above described bioreforming
processes, and can be used as a feedstock to provide the synthetic
cyclo-paraffinic kerosene fuel blending component of the present
invention.
[0060] In its application, a bioreforming process is used to
convert oxygenated hydrocarbons to an intermediate stream of mixed
oxygenates, with the resulting mixed oxygenates subsequently
converted to C.sub.8+ compounds containing the desired synthetic
cyclo-paraffinic kerosene fuel blending component. Examples of
various oxygenated hydrocarbons include any one or more sugars,
such as glucose, fructose, sucrose, maltose, lactose, mannose or
xylose, or sugar alcohols, such as arabitol, erythritol, glycerol,
isomalt, lactitol, malitol, mannitol, sorbitol, xylitol, arabitol,
glycol, and other oxygenated hydrocarbons. Additional non-limiting
examples of oxygenated hydrocarbons include various alcohols,
ketones, aldehydes, furans, hydroxy carboxylic acids, carboxylic
acids, diols and triols.
[0061] The oxygenated hydrocarbons are reacted in an aqueous
solution with hydrogen over a deoxygenation catalyst to produce a
stream of mixed oxygenates. The oxygenates will generally include,
without limitation, oxygenated hydrocarbons having 1 to 4 oxygen
atoms (e.g., mono-, di-, tri- and tetra-oxygenated hydrocarbons).
The mono-oxygenated hydrocarbons typically include alcohols,
ketones, aldehydes, cyclic ethers, furans, and pyrans, while the
di-oxygenated hydrocarbons typically include diols, hydroxy
ketones, lactones, furfuryl alcohols, pyranyl alcohols, and
carboxylic acids.
[0062] The deoxygenation catalyst is a heterogeneous catalyst
having one or more active materials capable of catalyzing a
reaction between hydrogen and the oxygenated hydrocarbons to remove
one or more of the oxygen atoms from the oxygenated hydrocarbon to
produce the oxygenates described above. The active materials may
include, without limitation, Cu, Re, Fe, Ru, Ir, Co, Rh, Pt, Pd,
Ni, W, Os, Mo, Ag, Au, alloys and combinations thereof, adhered to
a support. The deoxygenation catalyst may include these elements
alone or in combination with one or more Mn, Cr, Mo, W, V, Nb, Ta,
Ti, Zr, Y, La, Sc, Zn, Cd, Ag, Au, Sn, Ge, P, Al, Ga, In, Tl, Ce
and combinations thereof. The support may be any one of a number of
supports, including a support having carbon, silica, alumina,
zirconia, titania, tungsten, vanadia, chromia, zeolites,
heteropolyacids, kieselguhr, hydroxyapatite, and mixtures thereof.
The deoxygenation catalyst may also include an acidic support
modified or constructed to provide a desired functionality.
Heteropolyacids are a class of solid-phase acids exemplified by
such species as H.sub.3+xPMo.sub.12-xV.sub.xO.sub.40,
H.sub.4SiW.sub.12O.sub.40, H.sub.3PW.sub.12O.sub.40, and
H.sub.6P2W.sub.18O.sub.62, and have a well-defined local structure,
the most common of which is the tungsten-based Keggin
structure.
[0063] To produce oxygenates, a stream of oxygenated hydrocarbons
is combined with water to provide an aqueous feedstock solution.
The feedstock solution is then reacted with hydrogen in the
presence of the deoxygenation catalyst at deoxygenation temperature
and pressure conditions, and weight hourly space velocity,
effective to produce the desired oxygenates. In condensed phase
liquid reactions, the pressure within the reactor must be
sufficient to maintain the reactants in the condensed liquid phase
at the reactor inlet. For liquid phase reactions, the reaction
temperature may be from about 80.degree. C. to 300.degree. C., and
the reaction pressure from about 72 psig to 1300 psig. For vapor
phase reactions, the reaction should be carried out at a
temperature where the vapor pressure of the oxygenated hydrocarbon
is at least about 0.1 atm (and preferably a good deal higher), and
the thermodynamics of the reaction are favorable. This temperature
will vary depending upon the specific oxygenated hydrocarbon
compound used, but is generally in the range of from about
100.degree. C. to 600.degree. C. for vapor phase reactions.
[0064] The synthetic cyclo-paraffinic kerosene fuel blending
component is subsequently produced using an acid condensation
catalyst and a reactant stream that includes the mixed oxygenate
stream above as a first reactant and a second reactant having an
average oxygen to carbon ratio of 0.2 or less, in the presence of
water. The first reactant (i.e., the mixed oxygenates produced
above) can be generally described as having the formula
C.sub.xH.sub.yO.sub.z, with x representing 2 to 12 carbon atoms and
z representing 1 to 12 oxygen atoms, and an average oxygen to
carbon ratio of between 0.2 and 1.0. Collectively, the average
oxygen to carbon ratio of the first reactant should be about 0.2 to
1.0, calculated as the total number of oxygen atoms (z) in the
oxygenates of the first reactant divided by the total number of
carbon atoms (x) in the oxygenates of the first reactant.
Alternatively, the first reactant may have an average oxygen
content per molecule of about 1 to 4, calculated as the total
number of oxygen atoms (z) in the oxygenates of the first reactant
divided by the total number of molecules of oxygenates in the first
reactant. The total number of carbon atoms per molecule, oxygen
atoms per molecule and total molecules in the first reactant may be
measured using any number of commonly known methods, including (1)
speciation by gas chromatography (GC), high performance liquid
chromatography (HPLC), and other methods known to the art and (2)
determination of total oxygen, carbon, and water content by
elemental analysis. Oxygen present in water, carbon dioxide, or
carbon monoxide is excluded from the determination of reactant
oxygen to carbon ratio.
[0065] The second reactant includes one or more hydrocarbons and/or
oxygenated hydrocarbons having a general formula
C.sub.pH.sub.rO.sub.s, with p representing 2 to 7 carbon atoms ands
representing 0 to 1 oxygen atoms. When the second reactant is
derived from a recycle stream as described below, the second
reactant may also contain residual oxygenated hydrocarbons
containing 2 oxygen atoms. Collectively, the average oxygen to
carbon ratio of the second reactant should be less than 0.2,
calculated as the total number of oxygen atoms(s) in the oxygenated
hydrocarbons of the second reactant divided by the total number of
carbon atoms (p) in the hydrocarbons and oxygenated hydrocarbons of
the second reactant. Alternatively, the second reactant may have an
average oxygen per molecule ratio of less than 1.5, calculated as
the total number of oxygen atoms (s) in the oxygenated hydrocarbons
of the second reactant divided by the total number of molecules of
hydrocarbons and oxygenated hydrocarbons in the second reactant.
The second reactant may also be characterized as having an average
normal boiling point of less than 210.degree. C., or less than
200.degree. C., or less than 190.degree. C.
[0066] The second reactant will generally include C.sub.7- alkanes,
C.sub.7- alkenes, C.sub.7- cycloalkanes, C.sub.7- cycloalkenes,
C.sub.7- alcohols, C.sub.7- ketones, C.sub.7- aryls, and mixtures
thereof. Examples of the second reactant compounds include, without
limitation, C.sub.7- alkanes and C.sub.7- alkenes having from 4 to
7 carbon atoms (C.sub.4-7 alkanes and C.sub.4-7 alkenes), such as
butane, iso-butane, butene, isobutene, pentane, pentene,
2-methylbutane, hexane, hexene, 2-methylpentane, 3-methylpentane,
2,2-dimethylbutane, 2,3-dimethylbutane, cyclohexane, heptane,
heptene, methyl-cyclohexane and isomers thereof. The C.sub.7- aryls
will generally consist of an aromatic hydrocarbon having 6 or 7
carbon atoms, whether in either an unsubstituted (phenyl),
mono-substituted or multi-substituted form. The C.sub.7-
cycloalkanes and C.sub.7- cycloalkenes have 5, 6 or 7 carbon atoms
and may be unsubstituted, mono-substituted or multi-substituted. In
the case of mono-substituted and multi-substituted compounds, the
substituted group may include straight chain C.sub.1-2 alkyls,
straight chain C.sub.2 alkylenes, straight chain C.sub.2 alkynes,
or combinations thereof. Examples of desirable C.sub.7-
cycloalkanes and C.sub.7- cycloalkenes include, without limitation,
cyclopentane, cyclopentene, cyclohexane, cyclohexene,
methyl-cyclopentane, methyl-cyclopentene, ethyl-cyclopentane,
ethyl-cyclopentene, and isomers thereof.
[0067] The second reactant may be provide from any source, but is
preferably derived from biomass or a biomass-derived feedstock. For
example, although a biomass-derived feedstock is preferred, it is
contemplated that all or a portion of the second reactant may
originate from fossil fuel based compounds, such as natural gas or
petroleum. All or a portion of the second reactant may also
originate from any one or more fermentation technologies,
gasification technologies, Fischer-Tropsch reactions, or pyrolysis
technologies, among others. Preferably, at least a portion of the
second reactant is derived from the product stream and recycled to
be combined with the first reactant to provide at least a portion
of the reactant stream.
[0068] When a portion of the second reactant is derived from the
product stream following the condensation reaction, the product
stream is separated into a first portion containing C.sub.8+
compounds and a second portion containing C.sub.7- compounds to be
recycled and used as a portion of the second reactant.
Alternatively, the product stream may be first separated to a water
fraction and an organic fraction, with the organic fraction then
separated into a first portion containing the desired C.sub.8+
compounds and a second portion containing the C.sub.7- compounds to
be recycled and used as a portion of the second reactant. Processes
for separating liquid mixtures into their component parts or
fractions are commonly known in the art, and often involve the use
of a separator unit, such as one or more distillation columns,
phase separators, extractors, purifiers, among others.
[0069] The condensation reaction is performed using catalytic
materials that exhibit acidic activity. These materials may be
augmented through the addition of a metal to allow activation of
molecular hydrogen for hydrogenation/dehydrogenation reactions. The
acid condensation catalyst may be either an acidic support or an
acidic heterogeneous catalyst comprising a support and an active
metal, such as Pd, Pt, Cu, Co, Ru, Cr, Ni, Ag, alloys thereof, or
combinations thereof. The acid condensation catalyst may include,
without limitation, aluminosilicates, tungstated aluminosilicates,
silica-alumina phosphates (SAPOs), aluminum phosphates (ALPO),
amorphous silica alumina (ASA), acidic alumina, phosphated alumina,
tungstated alumina, zirconia, tungstated zirconia, tungstated
silica, tungstated titania, tungstated phosphates, acid modified
resins, heteropolyacids, tungstated heteropolyacids, silica,
alumina, zirconia, titania, tungsten, niobia, zeolites, mixtures
thereof, and combinations thereof. The acid condensation catalyst
may include the above alone or in combination with a modifier or
metal, such as Re, Cu, Fe, Ru, Ir, Co, Rh, Pt, Pd, Ni, W, Os, Mo,
Ag, Au, alloys thereof, and combinations thereof.
[0070] Examples of applicable acidic condensation catalysts include
bifunctional pentasil zeolites, such as ZSM-5, ZSM-8 or ZSM-11. The
zeolite with ZSM-5 type structure is a particularly preferred
catalyst. Other suitable zeolite catalysts include ZSM-12, ZSM-22,
ZSM-23, ZSM-35 and ZSM-48. Zeolite ZSM-5, and the conventional
preparation thereof, is described in U.S. Pat. Nos. 3,702,886, Re.
29,948 (highly siliceous ZSM-5), U.S. Pat. Nos. 4,100,262 and
4,139,600, all incorporated herein by reference. Zeolite ZSM-11,
and the conventional preparation thereof, is described in U.S. Pat.
No. 3,709,979, which is also incorporated herein by reference.
Zeolite ZSM-12, and the conventional preparation thereof, is
described in U.S. Pat. No. 3,832,449, incorporated herein by
reference. Zeolite ZSM-23, and the conventional preparation
thereof, is described in U.S. Pat. No. 4,076,842, incorporated
herein by reference. Zeolite ZSM-35, and the conventional
preparation thereof, is described in U.S. Pat. No. 4,016,245,
incorporated herein by reference. Another preparation of ZSM-35 is
described in U.S. Pat. No. 4,107,195, the disclosure of which is
incorporated herein by reference. ZSM-48, and the conventional
preparation thereof, is taught by U.S. Pat. No. 4,375,573,
incorporated herein by reference. Other examples of zeolite
catalysts are described in U.S. Pat. No. 5,019,663 and U.S. Pat.
No. 7,022,888, also incorporated herein by reference.
[0071] The specific C.sub.8+ compounds produced will depend on
various factors, including, without limitation, the make-up of the
reactant stream, the type of oxygenates in the first reactant, the
hydrocarbons and oxygenated hydrocarbons in the second reactant,
the concentration of the water, condensation temperature,
condensation pressure, the reactivity of the catalyst, and the flow
rate of the reactant stream as it affects the space velocity (the
mass/volume of reactant per unit of catalyst per unit of time), gas
hourly space velocity (GHSV), and weight hourly space velocity
(WHSV). The condensation temperature and pressure conditions may be
selected to more favorably produce the desired products in the
vapor-phase or in a mixed phase having both a liquid and vapor
phase. In general, the condensation reaction should be conducted at
a temperature and pressure where the thermodynamics of the
reactions are favorable. In general, the condensation temperature
should be between 100.degree. C. and 400.degree. C. and the
reaction pressure between 72 psig and 2000 psig.
[0072] The above condensation reactions result in the production of
C.sub.8+ alkanes, C.sub.8+ alkenes, C.sub.8+ cycloalkanes, C.sub.8+
cycloalkenes, C.sub.8+ aryls, fused aryls, C.sub.8+ alcohols,
C.sub.8+ ketones, oxygenated C.sub.8+ aryls, oxygenated fused
aryls, and mixtures thereof. The C.sub.8+ alkanes and C.sub.8+
alkenes have 8 or more carbon atoms, and may be branched or
straight chained alkanes or alkenes. The C.sub.8+ alkanes and
C.sub.8+ alkenes may also include fractions containing C.sub.8,
C.sub.9, C.sub.10, C.sub.11, C.sub.12, C.sub.13, C.sub.14 compounds
(C.sub.8-14 fraction), or C.sub.12, C.sub.13, C.sub.14, C.sub.15,
C.sub.16, C.sub.17, C.sub.18, C.sub.19, C.sub.20, C.sub.21,
C.sub.22, C.sub.23, C.sub.24 compounds (C.sub.12-24 fraction), or
more than 25 carbon atoms (C.sub.25+ fraction), with the C.sub.8-14
fraction directed to the synthetic cyclo-paraffinic kerosene fuel
blending component, the C.sub.12-24 fraction directed to diesel
fuel, and the C.sub.25+ fraction directed to heavy oils and other
industrial applications. Examples of various C.sub.8+ alkanes and
C.sub.8+ alkenes include, without limitation, octane, octene,
2,2,4,-trimethylpentane, 2,3-dimethyl hexane,
2,3,4-trimethylpentane, 2,3-dimethylpentane, nonane, nonene,
decane, decene, undecane, undecene, dodecane, dodecene, tridecane,
tridecene, tetradecane, tetradecene, pentadecane, pentadecene,
hexadecane, hexadecane, heptyldecane, heptyldecene, octyldecane,
octyldecene, nonyldecane, nonyldecene, eicosane, eicosene,
uneicosane, uneicosene, doeicosane, doeicosene, trieicosane,
trieicosene, tetraeicosane, tetraeicosene, and isomers thereof.
[0073] The C.sub.8+ cycloalkanes and C.sub.8+ cycloalkenes have 8
or more carbon atoms and may be unsubstituted, mono-substituted or
multi-substituted. In the case of mono-substituted and
multi-substituted compounds, the substituted group may include a
branched C.sub.3+ alkyl, a straight chain C.sub.1+ alkyl, a
branched C.sub.3+ alkylene, a straight chain C.sub.2+ alkylene, a
straight chain C.sub.2+ alkyne, a phenyl or a combination thereof.
In one embodiment, at least one of the substituted groups include a
branched C.sub.3+ alkyl, a straight chain C.sub.1+ alkyl, a
branched C.sub.3+ alkylene, a straight chain C.sub.2+ alkylene, a
straight chain C.sub.2+ alkyne, a phenyl or a combination thereof.
Examples of desirable C.sub.8+ cycloalkanes and C.sub.8+
cycloalkenes include, without limitation, ethyl-cyclopentane,
ethyl-cyclopentene, ethyl-cyclohexane, ethyl-cyclohexene, and
isomers thereof.
[0074] The C.sub.8+ product compounds may also contain high levels
of alkenes, alcohols and/or ketones, which may be undesirable in
certain fuel applications or which lead to coking or deposits in
combustion engines, or other undesirable combustion products. In
such event, the C.sub.8+ compounds may undergo a finishing step.
The finishing step will generally involve a hydrotreating reaction
that removes a portion of the remaining carbon-carbon double bonds,
carbonyl, hydroxyl, acid, ester, and ether groups.
[0075] The moderate fractions above (C.sub.8-C.sub.18) may be
separated for use as the synthetic cyclo-paraffinic kerosene fuel
blending component, while the C.sub.12-C.sub.24 fraction may be
separated for diesel fuel, and the heavier fraction (C.sub.25+)
separated for use as a heavy oil or cracked to produce additional
gasoline and/or diesel fractions. A C.sub.12-C.sub.18 fraction can
also be separated for rocket fuel applications. Separation
processes are well known in the art and generally involve one or
more distillation columns designed to facilitate the separation of
desired compounds from a product stream. The distillation will be
generally operated at a temperature, pressure, reflux ratio, and
with an appropriate equipment design, to recover the portion of the
C.sub.8+ compounds which conform to the boiling point
characteristics of the synthetic cyclo-paraffinic kerosene fuel
blending component as described above.
Additional Propulsion Fuel Blending Component
[0076] The additional propulsion fuel blending component may be any
fuel blending component which can be considered a kerosene base
fuel as described above. The additional propulsion fuel blending
component may also be naphtha generally used for blending to
manufacture Jet B fuel.
Other Components
[0077] Optionally, the fuel composition may further comprise a fuel
additive known to a person of ordinary skill in the art. In certain
embodiments, the fuel additive can be used from about 0.00005% by
weight to about 0.20% by volume, based on the total weight or
volume of the fuel composition. The fuel additive can be any fuel
additive approved for use in jet fuel or rocket fuel known to those
of skill in the art. In further embodiments, the fuel additive may
be antioxidants, thermal stability improvers, lubricity improvers,
fuel system icing inhibitors, metal deactivators, static
dissipaters, other aviation-approved additives and combinations
thereof.
[0078] The amount of a fuel additive in the fuel composition
disclosed herein may be from about 0.00005% by weight to less than
about 0.20% by volume, based on the total amount of the fuel
composition. In some embodiments, the amount is in wt. % based on
the total weight of the fuel composition. In other embodiments, the
amount is in vol. % based on the total volume of the fuel
composition. In yet other embodiments, the amount is in mass per
volume of the fuel composition. The amount will normally be within
limits mandated or recommended within the appropriate fuel
specification.
[0079] Illustrative examples of fuel additives are described in
greater detail below. Lubricity improvers are one example. They
were first used in aviation fuels as corrosion inhibitors to
protect ferrous metals in fuel handling systems, such as pipelines
and fuel storage tanks, from corrosion. It was discovered that they
also provided additional lubricity performance, reducing the wear
in components of the aircraft engine fuel system, such as gear
pumps and splines, where thin fuel layers separate moving metal
components. Nowadays, these additives are only used for lubricity
improvement. The lubricity improver may be present in the fuel
composition at a concentration up to about 23 mg/L, based on the
total volume of the fuel composition, and in accordance with jet
fuel specification limits.
[0080] Antioxidants can also be used herein. Antioxidants prevent
the formation of gum depositions on fuel system components caused
by oxidation of fuels in storage and/or inhibit the formation of
peroxide compounds in certain fuel compositions. The antioxidant
may be present in the fuel composition at a concentration up to 24
mg/L, based on the total volume of the fuel composition.
[0081] Static dissipaters reduce the effects of static electricity
generated by movement of fuel through high flow-rate fuel transfer
systems. The static dissipater may be present in the fuel
composition at a concentration up to about 5 mg/L, based on the
total volume of the fuel composition.
[0082] Fuel system icing inhibitors (also referred to as anti-icing
additives) reduce the freezing point of water precipitated from jet
fuels due to cooling at high altitudes and prevent the formation of
ice crystals which could restrict the flow of fuel to the engine.
Certain fuel system icing inhibitors can also act as a biocide. The
fuel system icing inhibitor may be present intentionally in the
fuel composition at a concentration from about 0.02 to about 0.2
volume %, based on the total volume of the fuel composition.
[0083] Metal deactivators suppress the catalytic effect that some
metals, particularly copper, have on fuel oxidation. The metal
deactivator may be present in the fuel composition at a
concentration up to about 5.7 mg/L active matter, based on the
total volume of the fuel composition.
[0084] Thermal stability improvers are used to inhibit deposit
formation in the high temperature areas of the aircraft fuel
system. The thermal stability improver may be present in the fuel
composition at a concentration up to about 256 mg/L, based on the
total volume of the fuel composition.
Blending and Using
[0085] In certain embodiments, volumetric energy content of a jet
fuel can be increased with minimal increase of the aromatic content
of the fuel. By the term minimal increase of aromatic content,
typically the increase in aromatic content is less than 2 vol %,
preferably less than 1.5 vol %, or preferably without an increase
that is within the precision of measurement for aromatic content,
or preferably even decreasing, based on the jet fuel. Higher
volumetric energy content is usually associated with higher
aromatics. Thus, it is unexpected to increase the volumetric energy
content of a fuel without an increase in its aromatic content.
[0086] A quantity of kerosene base fuel as described above (which
is different or other than cyclo-paraffinic kerosene fuel blending
component) may be blended with a quantity of the synthetic
cyclo-paraffinic kerosene fuel blending component in an amount
effective or sufficient to increase the volumetric energy content
of the final blended fuel compared to the kerosene base fuel,
preferably at least 0.1% increase in the volumetric energy content
as calculated from the Net Heat of Combustion estimated by ASTM
D3338 and multiplied by density.
[0087] In some embodiments, the smoke point of the blended fuel may
also increase compared with the kerosene base fuel.
[0088] Optionally, the blended fuel may be blended with an
additional propulsion fuel blending component to produce the
kerosene-based propulsion fuel.
[0089] The propulsion fuel may be blended at refineries or
terminals, in tankers, or at the location of application, as well
as at any other location that may have blending capabilities.
Various methods and equipment required for such blending activities
are commonly known in the art, and may be applied as needed
depending on the particular propulsion fuel desired.
[0090] The amount of the synthetic cyclo-paraffinic kerosene fuel
blending component may suitably be in an amount of 1 to 97 vol. %,
preferably 3 to 97 vol. %, preferably 5 to 97 vol. %, more
preferably 10 to 97 vol. %, more preferably 15 to 97 vol. %
provided that the amount is sufficient to increase volumetric
energy content at least 0.1%. The amount may vary depending on the
kerosene base fuel and/or the desired specification to upgrade to
and/or amount of desired volumetric energy content increase
desired. The amount of the synthetic cyclo-paraffinic kerosene fuel
blending component of the blend is preferably at least 1 vol. %,
preferably at least 3 vol. %, more preferably at least 5 vol. %,
more preferably at least 10 vol. %, more preferably at least 15
vol. %, based on the blended fuel. The amount of the synthetic
cyclo-paraffinic kerosene fuel blending component will vary
depending on the kerosene base fuel used.
[0091] The kerosene base fuel may be upgraded to meet Jet A-1
specification or JP-8 specification (e.g., when the kerosene base
fuel has a freezing point of above -47.degree. C.) by blending the
synthetic cyclo-paraffinic kerosene fuel blending component in an
amount effective or sufficient to lower the freezing point of the
blended fuel to -47.degree. C. or lower. For example, Jet A or F-24
jet fuel may be upgraded to meet Jet A-1 or JP-8 specification in
such manner
[0092] In some embodiments, the kerosene base fuel may be upgraded
to meet AN-8 specification (e.g., when the kerosene base fuel has a
freezing point of above -58.degree. C.) by blending the synthetic
cyclo-paraffinic kerosene fuel blending component in an amount
effective or sufficient to lower the freezing point of the blended
fuel to -58.degree. C. or lower. For example, any one of Jet A,
F-24, Jet A-1, JP-8, or JP-5 jet fuel may be upgraded to meet Jet
AN-8 specification.
[0093] In some embodiments, the kerosene base fuel is upgraded to
meet Jet A specification (e.g., when the kerosene base fuel have a
freezing point of above -40.degree. C.) by blending the synthetic
cyclo-paraffinic kerosene fuel in an amount effective or sufficient
to lower the freezing point of the blended fuel to -40.degree. C.
or lower. For example, refinery streams, synthetic fuel streams and
mixtures thereof that have a freezing point of above -40.degree. C.
and/or have a density of at least 760 kg/m.sup.3 may be upgraded to
meet Jet A specification.
[0094] In certain embodiments, a kerosene fuel can be upgraded to
meet Jet A-1 specification or JP-8 specification by;
[0095] a. providing a quantity of kerosene base fuel having a
boiling point in the range of 130.degree. C. to 300.degree. C., at
atmospheric pressure, flash point of 38.degree. C. or above
measured by above measured by ASTM D56, a density at 15.degree. C.
of at least 775 kg/m.sup.3 and freezing point of above -47.degree.
C.;
[0096] b. providing a quantity of synthetic cyclo-paraffinic
kerosene fuel blending component described above; and
[0097] c. blending a quantity of the synthetic cyclo-paraffinic
kerosene fuel blending component to the kerosene base fuel in
amount sufficient to lower the freezing point of the blended fuel
to -47.degree. C. or lower.
[0098] In certain embodiments, a kerosene fuel can be upgraded to
meet AN-8 specification by;
[0099] a. providing a quantity of kerosene base fuel having a
boiling point in the range of 130.degree. C. to 300.degree. C., at
atmospheric pressure, flash point of 38.degree. C. or above
measured by ASTM D56, and a density at 15.degree. C. of at least
775 kg/m.sup.3 and freezing point of above -58.degree. C.;
[0100] b. providing a quantity of synthetic cyclo-paraffinic
kerosene fuel blending component described above; and
[0101] c. blending a quantity of the synthetic cyclo-paraffinic
kerosene fuel blending component to the kerosene base fuel in
amount sufficient to lower the freezing point of the blended fuel
to -58.degree. C. or lower.
[0102] In certain embodiments, a kerosene fuel can be upgraded to
meet Jet A specification by;
[0103] a. providing a quantity of kerosene base fuel having a
boiling point in the range of 130.degree. C. to 300.degree. C., at
atmospheric pressure, flash point of 38.degree. C. or above
measured by ASTM D56, a density at 15.degree. C. of at least 760
kg/m.sup.3 and freezing point of above -40.degree. C.;
[0104] b. providing a quantity of synthetic cyclo-paraffinic
kerosene fuel blending component described above; and
[0105] c. blending a quantity of the synthetic cyclo-paraffinic
kerosene fuel blending component to the kerosene base fuel in
amount sufficient to lower the freezing point of the blended fuel
to -40.degree. C. or lower.
[0106] In some embodiments, the blended jet fuel may preferably
have a density of equal or above 800 kg/m.sup.3. The blended jet
fuel may preferably have an aromatic content of less than or equal
to 25 vol %, more preferably less than or equal to 20 vol %.
[0107] In some embodiments, the inventive method may be used to
meet any of the standard specifications for Aviation Turbine fuels
described above.
[0108] The increase in volumetric energy content and/or smoke point
increase can be seen by operating a jet engine comprising burning
the jet fuel produced by the method described above in such jet
engine.
[0109] In another aspect, a fuel system is provided comprising a
fuel tank containing the fuel composition produced by the methods
described above. Optionally, the fuel system may further comprise
an engine cooling system having a recirculating engine coolant, a
fuel line connecting the fuel tank with the internal combustion
engine, and/or a fuel filter arranged on the fuel line. Some
non-limiting examples of internal combustion engines include
reciprocating engines (e.g., diesel engines), jet engines, some
rocket engines, and gas turbine engines.
[0110] In some embodiments, the fuel tank is arranged with a
cooling system so as to allow heat transfer from the recirculating
engine coolant to the fuel composition contained in the fuel tank.
In other embodiments, the fuel system further comprises a second
fuel tank containing a second fuel for a jet engine and a second
fuel line connecting the second fuel tank with the engine.
Optionally, the first and second fuel lines can be provided with
electromagnetically operated valves that can be opened or closed
independently of each other or simultaneously.
[0111] In another aspect, an engine arrangement is provided
comprising an internal combustion engine, a fuel tank containing
the fuel composition disclosed herein, a fuel line connecting the
fuel tank with the internal combustion engine. Optionally, the
engine arrangement may further comprise a fuel filter and/or an
engine cooling system comprising a recirculating engine coolant. In
some embodiments, the internal combustion engine is a jet
engine.
[0112] The smoke point increase can be seen by burning the jet fuel
produced by the methods described above by providing the jet fuel
to the fuel system and/or jet engine and operating such fuel system
and/or jet engine.
[0113] Rocket fuel can be used in a rocket engine system that
includes a combustion chamber, an oxidizer supply, a fuel delivery
circuit connected to a fuel supply, a faceplate having a plurality
of openings therethrough, and an injector assembly positioned at
the combustion chamber. Such a system is described, for example, in
U.S. Pat. No. 7,685,807 and U.S. Pat. No. 7,827,781.
[0114] A liquid rocket fuel useful to meet RP-1 or RP-2 grade
rocket fuels may be produced by blending a quantity of the
synthetic cyclo-paraffinic kerosene fuel blending component and a
quantity of the kerosene range hydrocarbon component in amount
sufficient to meet a flash point of at least 60.degree. C. and a
final boiling point of 274.degree. C. or lower. The blended rocket
fuel preferably have a freezing point of -51.degree. C. or below, a
flash point of at least 60.degree. C., a density in the range of
799-815 kg/m.sup.3 at 15.degree. C., and a volumetric energy
density in the range of 34,380-35,070 MJ/m.sup.3. The blended
rocket fuel can also have a hydrogen content of at least 13.8 mass
%. In one embodiment, the net heat of combustion of the blended
rocket fuel is at least 43.03 MJ/kg. The blended rocket fuel can
also have a sulfur content of no more than 0.0030 mass %. The
sulfur requirement for RP-1 is 0.0030 mass % or below and RP-2
0.00001 mass % or below by ASTM D-5623. The liquid rocket fuel may
also be blended to meet a thermal stability requirement at a
temperature of at least 355.degree. C. The preferable amount of
synthetic cyclo-paraffinic kerosene fuel blending component in the
final liquid rocket fuel is at least 1 vol. %, preferably at least
3 vol. %, preferably at least 5 vol. %, preferably at least 10 vol.
%, preferably at least 15 vol. %, preferably at least 20 vol. %,
preferably at least 25 vol. %, or more preferably at least 30 vol.
%, based on the final rocket fuel blend. The preferable amount of
synthetic cyclo-paraffinic kerosene fuel blending component in the
final liquid rocket fuel is at most 97 vol. %, preferably at most
95 vol. %, preferably at most 90 vol. %, preferably at most 85 vol.
%, preferably at most 80 vol. %, or more preferably at most 75 vol.
%, based on the final rocket fuel blend.
[0115] By blending a quantity of the synthetic cyclo-paraffinnc
kerosene fuel blending component and a quantity of the kerosene
range hydrocarbon component, it was found that a higher quality
liquid fuel suitable for use as liquid rocket fuel may be produced.
The blended liquid rocket fuel may be considered to be a biofuel
containing rocket fuel.
[0116] In an embodiment of the invention, it has been found that a
rocket fuel blend can be produced that has a -34.degree. C.
kinematic viscosity (measured according to ASTM D445 method) that
is less than 10 cSt, more preferably less than 9 cSt, and most
preferably less than 8 cSt. Rocket fuels with lower viscosities at
sub-zero temperatures can be further cooled, maximizing the benefit
of improved fuel densities at lower active fuel cooling
temperatures.
[0117] As used herein, a "low" or "lower" in the context of
propulsion fuel properties embraces any degree of decrease or
reduction compared to an average commercial petroleum jet fuel
property containing equivalent total aromatics content under the
same or equivalent conditions.
[0118] As used herein, a "high" or "higher" in the context of
propulsion fuel properties embraces any degree of increase compared
to an average commercial petroleum jet fuel property containing
equivalent total aromatics content under the same or equivalent
conditions.
[0119] As used herein, an "increase" in the context of propulsion
properties embraces any degree of increase compared to a previously
measured jet fuel property under the same or equivalent conditions.
Thus, the increase is suitably compared to the jet fuel property of
the fuel composition prior to incorporation of the synthetic
cyclo-paraffinic kerosene fuel blending component. Alternatively,
the property increase may be measured in comparison to an otherwise
analogous jet fuel composition (or batch or the same fuel
composition); for example, which is intended (e.g., marketed) for
use in a jet turbine engine, without adding the bio-based
cyclo-paraffinic kerosene fuel blending component to it.
[0120] As used herein, a "decrease" or "reduction" in the context
of propulsion fuel properties embraces any degree of decrease or
reduction compared to a previously measured jet fuel property under
the same or equivalent conditions. Thus, the decrease or reduction
is suitably compared to the property of the jet fuel composition
prior to incorporation of the synthetic cyclo-paraffinic kerosene
fuel blending component. Alternatively, the property decrease may
be measured in comparison to an otherwise analogous jet fuel
composition (or batch or the same fuel composition); for example,
which is intended (e.g., marketed) for use in a jet turbine engine,
without adding the synthetic cyclo-paraffinic kerosene fuel
blending component to it.
[0121] In the context of the present invention, "use" of a
synthetic cyclo-paraffinic kerosene fuel blending component in a
propulsion fuel composition means incorporating the component into
the jet fuel, typically as a blend (i.e., a physical mixture) with
one or more jet fuel components and optionally with one or more jet
fuel additives.
[0122] Accordingly, in one embodiment of the invention, there is
provided the use of a synthetic cyclo-paraffinic kerosene fuel
blending component described above to increase the volumetric
energy content of a jet fuel. Accordingly, in another embodiment of
the invention, there is provided the use of a synthetic
cyclo-paraffinic kerosene fuel blending component described above
to upgrade a kerosene base fuel to meet a Jet A-1 specification.
Accordingly, in another embodiment of the invention, there is
provided the use of a synthetic cyclo-paraffinic kerosene fuel
blending component described above to upgrade a kerosene base fuel
to meet a Jet A specification. Accordingly, in another embodiment
of the invention, there is provided the use of a synthetic
cyclo-paraffinic kerosene fuel blending component described above
to upgrade a kerosene base fuel to meet a Jet AN-8
specification.
[0123] Suitably, the synthetic cyclo-paraffinic kerosene fuel
blending component described above is used in an amount to increase
the smoke point, preferably to increase the smoke point at least 1
mm greater than the kerosene base fuel (e.g., petroleum based jet
fuel) as measured by ASTM D1322 (automated method). When using a
jet fuel composition prepared by the method disclosed herein, a jet
airplane equipped with a jet turbine engine, a fuel tank containing
the jet fuel composition prepared according to methods disclosed
herein, and a fuel line connecting the fuel tank with the jet
turbine engine. Thus, a jet engine may be operated by burning in
such jet engine a jet fuel described herein.
[0124] Accordingly, in another embodiment of the invention, there
is provided the use of a synthetic cyclo-paraffinic kerosene fuel
blending component comprising at least 99.5mass % of carbon and
hydrogen content and at least 50 mass % of cyclo-paraffin, said
cyclo-paraffinic kerosene fuel blending component having a boiling
point of at most 300.degree. C., at atmospheric pressure, flash
point of at least 38.degree. C., a density at 15.degree. C. of at
least 799 kg/m.sup.3, and a freezing point of -60.degree. C. or
lower, to produce a liquid rocket fuel.
[0125] While the invention is susceptible to various modifications
and alternative forms, specific embodiments thereof are shown by
way of examples herein described in detail. It should be
understood, that the detailed description is not intended to limit
the invention to the particular form disclosed, but on the
contrary, the intention is to cover all modifications, equivalents
and alternatives falling within the spirit and scope of the present
invention as defined by the appended claims. The person skilled in
the art will readily understand that, while the invention is
illustrated making reference to one or more a specific combinations
of features and measures, many of those features and measures are
functionally independent from other features and measures such that
they can be equally or similarly applied independently in other
embodiments or combinations.
[0126] The present invention will be illustrated by the following
illustrative embodiment, which is provided for illustration only
and is not to be construed as limiting the claimed invention in any
way.
ILLUSTRATIVE EXAMPLES
Test Methods
Jet Fuel Specification Tests and Methods
[0127] A jet fuel can be verified to meet a given specification by
testing the fuel's properties specified by the governing
specification.
Energy Per Unit Volume or Energy Per Unit Mass
[0128] The energy per unit mass (or gravimetric energy density) of
a fuel is simply its Net Heat of Combustion as determined by ASTM
D3338. The energy per unit volume (or volumetric energy density)
can be calculated by multiplying the fuel's Net Heat of Combustion
(determined by ASTM D3338) by the fuel's density (determined by
ASTM D4052).
Materials
COMPARATIVE EXAMPLES
[0129] A petroleum-derived jet fuel sourced from Convent Terminal
in Convent, Louisiana is provided as a comparative example of Jet A
or a kerosene base fuel component. A synthetic jet fuel component
sourced from Shell Middle Distillate Synthesis plant in Bintulu,
Malaysia having (99.9 wt.% paraffin content with iso-paraffin and
n-paraffin content of 98.7 wt. %) is provided as a comparative
example of GTL1. Another synthetic jet fuel component sourced from
Pearl GTL plant in Qatar having (100.0 wt. % paraffin content with
iso-paraffin and n-paraffin content of 96.3 wt. %) is provided as a
comparative example of GTL2. A jet fuel component from
hydroprocessed esters and fatty acid sourced from UOP having (98.1
mass % paraffins, 1.9 mass % cyclo-paraffins) is provided as a
comparative example of HEFA. The specification properties for each
comparative example are summarized in Table 3 below.
TABLE-US-00003 TABLE 3 Specification Properties of Fuel Components
ASTM Test Method Jet A GTL1 GTL2 HEFA Acidity (mgKOH/g) D3242 0.003
0.001 0.001 0.003 Density at 15.degree. C. (-kg/m.sup.3) D4052
798.4 735.9 753.8 756.7 Hydrogen Content (mass %) D5291 14.005
15.595 15.42 14.73 Flash Point (.degree. C.) D56 45 43 56.5 43
Freeze Point (.degree. C.) D5972 -43.2 -54.6 -49.3 -57.3 Viscosity
(mm.sup.2/s) at -20.degree. C. D445 4.037 2.450 4.146 4.795 Total
Sulfur (ppm) D5453 NA <1* 1 <1* Total Sulfur (mass %) D4294
0.151 NA NA NA Mercaptan sulfur (mass %) D3227 6 NA NA NA Smoke
Point D1322 24.3 >50.0* >50.0* >50.0* (mm) (automated)
Naphthalenes (vol. %) D1840 1.26 NA 0.0 NA Aromatics (vol. %) D1319
17.5 NA NA NA D6379 NA 0.1 <0.1* 0.1 Net Heat of Combustion
D3338 43.318 44.246 44.136 44.145 (MJ/kg) Distillation Temperature
at 10% D86 176.2 161.0 184.4 162.9 Boiling Point (.degree. C.)
Final Boiling Point (.degree. C.) D86 274.4 195.9 234.3 277.8
*Actual values were beyond the indicated detection limit
Example 1
Production of Synthetic Cyclo-Paraffinic Kerosene from Corn
Starch
[0130] A three step catalytic process as described above utilizing
aqueous phase reforming (APR), dehydration/oligomerization (DHOG)
and hydrotreating (HT), was used to convert corn syrup to
cyclo-paraffin-rich organic product. Two distinct beds of APR
catalyst developed by Virent, Inc. (Madison, Wis.) were used. The
first APR catalyst included palladium, molybdenum, and tin metals
on a tungsten modified zirconia support, while the second APR
catalyst included palladium and silver metals on a tungsten
modified zirconia support. The DHOG catalyst included palladium and
silver metals on a tungsten modified zirconia support, also
provided by Virent, Inc. The HT catalyst was prepared by CRI with a
nickel metal loading on an alumina support.
[0131] The catalysts were loaded into separate fixed-bed, tubular
reactors configured in series such that the liquid product from one
step was fed to the next step. A 60% 43DE corn syrup in water
mixture by weight was fed across the system with the process
conditions shown in Table 4.
TABLE-US-00004 TABLE 4 Start of Run Conditions for APR, DHOG, and
HT APR APR I II DHOG HT WHSV wt.sub.feed/(wt.sub.catalyst hr) 0.8
0.8 0.8 1.6 Added mol.sub.H2/mol.sub.feed 1.4 0.8 -- 0.5 Hydrogen
Average .degree. C. 210 250 280 370 Reactor Temperature Pressure
Psig 1800 900 900 1300
[0132] A two-pass hydrotreating configuration was used. The
hydrotreating process included an intermediate distillation step in
between each pass to remove the components heavier than the
300.degree. C. end point for jet fuel. The liquid from the
HDO-DHOG-HT train was fractionated continuously within the same
plant. The SK fraction was collected, combined all together, and
re-fed across the HT catalyst and fractionation portion of the
plant at the same conditions shown in Table 4 for the HT step.
[0133] The resulting product composition of the liquid organic
product is shown in Table 5, which includes a comparison of the
composition and carbon number of the product pre-fractionation,
after the first HT pass, and after the second HT pass.
[0134] For alternative applications, the fractionation can be tuned
to produce a diesel fraction that is primarily C.sub.12-C.sub.24,
or a rocket fuel application that is primarily C.sub.12-C.sub.18
(rocket fuel cut).
TABLE-US-00005 TABLE 5 Liquid organic product composition by GCxGC
- Full Range and SK fraction SK Fraction Full Range SK Fraction
Post- Pre- Post-fractionation fractionation fractionation 1 Pass HT
2 Pass HT Speciation Cyclo-paraffins wt. % 37.3 52.2 82.2 Paraffins
wt. % 14.3 14.6 16.9 Aromatics wt. % 6.5 27.8 0.5 PNA wt. % 0.5 2.1
0.0 Unclassified* wt. % 41.4 3.4 0.6 Total wt. % 100.0 100.0 100.0
Carbon Number C7- wt. % 33.2 1.7 0.8 C8-C18 wt. % 52.4 95.6 98.5
C19+ wt. % 13.6 2.4 0.4 Unclassified wt. % 0.8 0.4 0.3 Total wt. %
100.0 100.0 100.0 *Method set up to look for compounds between
C7-C18 in jet fuel range, so C7- and C19+ compounds are not
classified into a class. In case of "Full Range" material, majority
of "Unclassified" compounds were paraffins.
The process was run to produce greater than 420 liters (110
gallons) of synthetic cyclo-paraffinic kerosene for product
testing. The product was stored in two 55 gallon drums and one 16
gallon drum. 20 milligrams per liter of butylated hydroxyltoluene
(BHT) anti-oxidant additive was added to each drum as is standard
fuel handling practice for jet fuel. Examples 3 were tested fuel
from this example.
Example 2
Production of Synthetic Cyclo-Paraffinic Kerosene from
Lignocellulose
[0135] A woody biomass material was deconstructed by a 3rd party to
produce a hydrolysate. This hydrolysate was ion exchanged to remove
inorganic impurities and diluted so the carbon containing fraction
was 50% by weight, with the balance being water.
[0136] A three step catalytic process as described in Example 1
utilizing aqueous phase reforming (APR),
dehydration/oligomerization (DHOG) and hydrotreating (HT) was used
to convert the hydrolysate to cyclo-paraffinic rich organic product
under the process conditions shown in Table 6.
TABLE-US-00006 TABLE 6 Process Conditions for APR and DHOG APR I
DHOG WHSV wt.sub.feed/(wt.sub.catalyst hr) 0.7 0.7 Added Hydrogen
mol.sub.H2/mol.sub.feed 6.4 1.1 Average Reactor Temperature
.degree. C. 210 270 Pressure psig 1050 600
[0137] An organic phase product from the APR-DHOG continuous system
was collected throughout the run, combined all together, and fed to
a separate plant to perform the hydrotreating (HT) step. The HT
step utilized a two-pass hydrotreating configuration as described
in Example 1, which included an intermediate distillation step
between each pass to remove the components heavier than the
300.degree. C. end point for jet fuel. The HT catalyst was prepared
by CRI with a nickel metal loading on an alumina support and loaded
into a fixed-bed, tubular reactor. A 1:1 co-loading of amorphous
silica alumina was used to distribute the catalyst.
TABLE-US-00007 TABLE 7 Process Conditions for HT I and II HT I HT
II WHSV wt.sub.feed/(wt.sub.catalyst 3 1.7 hr) Added Hydrogen
mol.sub.H2/mol.sub.feed 13.8 13.6 Average Reactor .degree. C. 290
290 Temperature Pressure psig 800 800
The product composition of the final SK liquid organic product is
shown in Table 8 Error! Reference source not found. The 3.sup.rd
column from Table 5 in Example 1 is included to show the similarity
of the product from both feedstock sources. Since the compositions
of the products are very similar, it follows that the physical
properties are very similar as well, as shown in Table 9.
TABLE-US-00008 TABLE 8 Liquid organic product composition by ASTM
D2425 Example 1 Example 2 Speciation Corn Syrup Woody Biomass
Cyclo-paraffins wt. % 83 74 Paraffins wt. % 17 25 Aromatics wt. %
<0.3* <0.3* Olefins wt. % <0.3* <0.3* PNA wt. %
<0.3* <0.3* Other wt. % <0.3* <0.3* Total wt. % 100 100
*Actual values were beyond the indicated detection limit
TABLE-US-00009 TABLE 9 Physical properties of SK produced from corn
syrup and biomass-derived feedstocks ASTM Example D1655 Example SK
1 Example SK 2 Jet A/A-1 Feedstock Test Spec Woody Specification
Test Method Requirement Corn Syrup Biomass Aromatics, vol. % D1319
.ltoreq.25 0.0 0.2 Heat of Combustion D4809 .gtoreq.42.8 43.3 43.3
(measured), MJ/kg Distillation: D86/D7345** IBP, .degree. C. 149
146 10% recovered, .ltoreq.205 178 172 .degree. C. 50% recovered,
217 227 .degree. C. 90% recovered, 266 280 .degree. C. EP, .degree.
C. .ltoreq.300 292 300 Residue, % vol. .ltoreq.1.5 1.2 2** Loss, %
vol. .ltoreq.1.5 0.7 0 Flash point, .degree. C. D56 .gtoreq.38 44
45 Freezing Point, .degree. C. D5972 .ltoreq.-47 <-78* <-60*
Density @ 15.degree. C., D4052 775-840 818 813 kg/m.sup.3 Thermal
Stability D3241 >260 .gtoreq.355 .gtoreq.325*** Breakpoint,
.degree. C. Net Heat of D3338 .gtoreq.42.8 43.3 43.3 combustion
(MJ/kg) *Actual values were beyond the indicated detection limit
**D7345 micro-distillation performed due to sample size, high
residue likely an artifact of test method. No HDO-SK sample
analyzed by D86 had a high residue. ***Sample not tested higher
than 325.degree. C. due to sample size, breakpoint at some
temperature higher.
Example 3
Comparative Jet Fuel Blends
[0138] Several series of Example and Comparative Example jet fuel
blends were prepared using Comparative Example Jet A, Example SK1
from Example 1, Comparative Example HEFA, Comparative Example GTL1,
and Comparative Example GTL2. These jet fuel blends and their
indicated blend ratios are summarized in Table 10.
TABLE-US-00010 TABLE 10 Jet A content (Vol. %) SK1 content (Vol. %)
Example 3-1 64.5 35.5 Series 3-2 43.0 57.0 3-3 32.3 67.7 3-4 26.9
73.1 3-5 21.5 78.5 3-6 10.8 89.2 HEFA content (Vol. %) Comparative
A-1 64.5 35.5 Example A-2 43.0 57.0 Series GTL1 content (Vol. %)
Comparative B-1 64.5 35.5 Example B-2 43.0 57.0 Series B-3 32.3
67.7 B-4 16.1 83.9 B-5 10.8 89.2 B-6 5.4 94.6 GTL2 content (Vol. %)
Comparative C-1 64.5 35.5 Example C-2 43.0 57.0 Series C-3 32.3
67.7 C-4 16.1 83.9 C-5 10.8 89.2 C-6 5.4 94.6
The Jet fuel Blends above were tested for jet fuel specification
properties. The results are provided in Tables 11 below.
[0139] Aromatic contents of the blends were calculated by linear
blending; that is, multiplying the percentage of Kerosene base fuel
(Jet A) in the comparative example blend by the aromatic content of
the Kerosene base fuel (as determined by D1319). Gravimetric and
volumetric energy densities of the two-component blends were
calculated by linear blending. That is, for components .alpha. and
.beta. with respective volumetric contents [.alpha.] and
1-[.alpha.], respective gravimetric energy densities
.gamma..sub..alpha. and .gamma..sub..beta., and respective
densities of .rho..sub..alpha. and .rho..sub..beta., the
gravimetric and volumetric energy densities of resulting blends can
be calculated as follows:
Gravimetric energy density of blend of .alpha. and
.beta.=[.alpha.]*.gamma..sub..alpha.+(1-[.alpha.])*.gamma..sub..beta.
Volumetric energy density of blend of .alpha. and
.beta.=[.alpha.]*.gamma..sub..alpha.*.rho..sub..alpha.+(1-[.alpha.])*.gam-
ma..sub..beta.*.rho..sub..beta.
TABLE-US-00011 TABLE 11-1 Key Specification Properties of Example
Series 3 SK1 content in SK1/Jet A blend (vol. %) 0.0 35.5 57.0 67.7
73.1 78.5 89.2 100.0 Comparative Examples ASTM Jet A 3-1 3-2 3-3
3-4 3-5 3-6 SK1 Test Method Property Aromatic D1319 or 18.6 12.0
8.0 6.0 5.0 4.0 2.0 0 Content (vol. %) calculated Density at
15.degree. C. D4052 0.7984 0.8037 0.8071 0.8087 0.8096 0.8104
0.8121 0.8138 (g/cm.sup.3) Freezing Point D5972 -43.2 -48.8 NA
-58.0 -61.1 -64.9 <-77.0* <-76.0* (.degree. C.) Smoke Point
D1322 24.3 26.1 27.9 28.3 29.3 29.9 30.2 31.3 (mm) (automated)
Hydrogen D5291 14.01 14.15 14.21 14.26 14.21 14.25 14.27 14.4
Content (mass %) Net Heat of D3338 or 43.3 43.3 43.3 43.3 43.3 43.3
43.3 43.4 Combustion or calculated Gravimetric Energy Density
(MJ/kg) Volumetric Calculated 34,600 34,900 35,000 35,100 35,100
35,100 35,200 35,300 Energy Density (MJ/m.sup.3) *Actual values
were beyond the indicated detection limit
TABLE-US-00012 TABLE 11-2 Key Specification Properties of
Comparative Example Series A HEFA content in HEFA/Jet A blend (vol
%) 0.0 43.0 64.5 100.0 Comparative Examples Jet A A-1 A-2 HEFA Test
ASTM Method Property Aromatic Content (vol. %) D1319 or calculated
18.6 12 8 0.0 Density at 15.degree. C. (g/cm.sup.3) D4052 0.7984
0.7839 0.7753 0.7570 Freezing Point (.degree. C.) D5972 -43.2 -45.9
-49.3 -57.5 Smoke Point (mm) D1322 24.3 30.65 36.35 >50.0*
(automated) Hydrogen Content (mass %) D5291 14.01 14.45 14.73 15.60
Net Heat of Combustion or D3338 or calculated 43.3 43.6 43.8 44.1
Gravimetric Energy Density (MJ/kg) Volumetric Energy Density
Calculated 34,600 34,200 33,900 33,400 (MJ/m.sup.3) *Actual values
were beyond the indicated detection limit
TABLE-US-00013 TABLE 11-3 Key Specification Properties of
Comparative Example Series B GTL1 content in GTL1/Jet A blend (vol.
%) 0.0 35.5 57.0 67.7 83.9 89.2 94.6 100.0 Comparative Examples
ASTM Jet A B-1 B-2 B-3 B-4 B-5 B-6 GTL1 Test Method Property
Aromatic D1319 or 18.6 12.0 8.0 6.0 3.0 2.0 1.0 0.0 Content (vol.
%) calculated Density at 15.degree. C. D4052 0.7984 0.7761 0.7636
0.7568 0.7467 0.7433 0.7396 0.7359 (g/cm.sup.3) Freezing Point
D5972 -43.2 -49.2 NA -58.1 NA NA -55.8 -54.6 (.degree. C.) Smoke
Point D1322 24.3 32.5 39.05 43.7 >50.0* >50.0* >50.0*
>50.0* (mm) (automated) Hydrogen D5291 14.01 14.55 14.84 15.06
15.31 15.40 15.52 15.60 Content (mass %) Net Heat of D3338 or 43.3
43.6 43.8 43.9 44.1 44.1 44.2 44.2 Combustion or calculated
Gravimetric Energy Density (MJ/kg) Volumetric Calculated 34,600
33,900 33,400 33,200 32,900 32,800 32,700 32,600 Energy Density
(MJ/m.sup.3) *Actual values were beyond the indicated detection
limit
TABLE-US-00014 TABLE 11-4 Key Specification Properties of
Comparative Example Series C GTL2 content in GTL2/Jet A blend (vol.
%) 0.0 35.5 57.0 67.7 83.9 89.2 94.6 100.0 Comparative Examples
ASTM Jet A C-1 C-2 C-3 C-4 C-5 C-6 GTL2 Test Method Property
Aromatic D1319 or 18.6 12.0 8.0 6.0 3.0 2.0 1.0 0.0 Content (vol.
%) calculated Density at 15.degree. C. D4052 0.7984 0.7823 0.7731
0.7682 0.7609 0.7586 0.7560 0.7538 (g/cm.sup.3) Freezing Point
D5972 -43.2 -47.2 NA -50.1 NA NA -49.5 -49.3 (.degree. C.) Smoke
Point D1322 24.3 31.4 37.6 42.3 49.9 >50.0* >50.0* >50.0*
(mm) (automated) Hydrogen D5291 14.01 14.47 14.78 14.93 15.18 15.21
15.32 15.42 Content (mass %) Net Heat of D3338 or 43.3 43.6 43.8
43.9 44.0 44.0 44.1 44.1 Combustion or calculated Gravimetric
Energy Density (MJ/kg) Volumetric Calculated 34,600 34,100 33,800
33,700 33,500 33,400 33,300 33,300 Energy Density (MJ/m.sup.3)
*Actual values were beyond the indicated detection limit
[0140] As can be seen from Table 11-1, SK1 can be blended to Jet A
to meet Jet A-1 specification as shown in Example 3-1 and can be
blended to meet AN-8 specification as shown in Example 3-3,
particularly without loss, but increase in volumetric energy
density.
[0141] FIG. 1 compares the volumetric energy density (MJ/m.sup.3)
of the jet fuel blends Example Series 3, Comparative Example Series
A, Comparative Example Series B, and Comparative Example Series C
based on paraffinic kerosene content in Jet A (vol. %). Also
included for completeness are the volumetric energy densities of
the neat blend components Comparative Example SK1, Comparative
Example HEFA, Comparative Example GTL1, Comparative Example GTL2,
and Comparative Example Jet A. The data show a linear blending
relationship for all blends. The slopes of all the Comparative
Example Series data are negative, indicating increased paraffinic
kerosene content (whether via HEFA, GTL1, or GTL2) typically
results in an undesirable decrease in volumetric energy density.
However, the slope of the Example 3 data is positive, indicating
that increased SK1 cyclo-paraffinic kerosene content resulted in
increased volumetric energy density. This demonstrates the unique
ability to blend a cyclo-paraffinic kerosene product such as SK1
into a kerosene base fuel without decreasing, but rather increase
volumetric energy density. This is desirable because higher
volumetric energy density results in aircraft flying greater
distances using the same volume of fuel, or in other words, with
greater payload range.
[0142] FIG. 2 compares the aromatics content (vol. %) versus
volumetric energy density (MJ/m.sup.3) of the jet fuel blends
Example Series 3, Comparative Example Series A, Comparative Example
Series B, and Comparative Example Series C. Also included for
completeness are the aromatics contents of the neat blend
components Comparative Example SK1, Comparative Example HEFA,
Comparative Example GTL1, Comparative Example GTL2, and Comparative
Example Jet A. The data show a linear blending relationship for all
blends. The slopes of all the Comparative Example Series data are
positive, indicating that increased volumetric energy density
typically requires an undesirable increase in aromatics content.
However, the slope of the Example Series 3 data is negative,
indicating increased volumetric energy density with decreasing
aromatics content. This demonstrates the unique ability to blend a
cyclo-paraffinic kerosene product such as SK1 into a kerosene base
fuel to decrease aromatics content without decreasing, but rather
increase volumetric energy density. This is desirable because lower
aromatics content improves engine operability and lifetime and
reduces soot emissions; and higher volumetric energy density
results in aircraft flying greater distances using the same volume
of fuel, or in other words, with greater payload range.
[0143] FIG. 3 compares the smoke point increase (mm) of jet fuel
with volumetric energy density (MJ/m.sup.3) of the jet fuel blends
Example 3, Comparative Example Series A,
[0144] Comparative Example Series B, and Comparative Example Series
C. Also included for completeness are the smoke points of the neat
blend components Comparative Example SK1, Comparative Example HEFA,
Comparative Example GTL1, Comparative Example GTL2, and Comparative
Example Jet A. The data show a non-linear blending relationship for
all blends. The slopes of all the Comparative Example Series data
are negative, indicating increased volumetric energy density
typically requires an undesirable decrease in smoke point. However,
the slope of the Example 3 data is positive, indicating increased
volumetric energy density with increasing smoke point. This
demonstrates the unique ability to blend a cyclo-paraffinic
kerosene product such as SK1 into a kerosene base fuel to increase
volumetric energy density without decreasing, but rather increase
smoke point. This is desirable because higher smoke point indicates
a cleaner-burning fuel; and higher volumetric energy density
results in aircraft flying greater distances using the same volume
of fuel, or in other words, with greater payload range.
[0145] FIG. 4 compares the freezing point increase (.degree. C.) of
jet fuel with volumetric energy density (MJ/m.sup.3) of the jet
fuel blends Example Series 3, Comparative Example Series A,
Comparative Example Series B, and Comparative Example Series C.
Also included for completeness are the freezing points of the neat
blend components Comparative Example SK1, Comparative Example HEFA,
Comparative Example GTL1, Comparative Example GTL2, and Comparative
Example Jet A. The data show a non-linear blending relationship for
all blends. The Comparative Example Series data indicate increased
volumetric energy density typically requires an undesirable
increase in freezing point. However, the Example 3 data show
increased volumetric energy density with decreasing freezing point.
This demonstrates the unique ability to blend a cyclo-paraffinic
kerosene product such as SK1 into a kerosene base fuel to increase
volumetric energy density without increasing, but rather decrease
the freezing point. This is desirable because a lower freezing
point enables a fuel to meet more stringent specifications (such as
for AN-8) or to fly more direct routes through colder areas, and
have wider applicability for cold environments; and higher
volumetric energy density results in aircraft flying greater
distances using the same volume of fuel, or in other words, with
greater payload range.
Example 4
Production of Modified Synthesized Cyclo-Paraffinic Kerosene for
Rocket Fuel Applications
[0146] A fraction of cyclo-paraffinic kerosene can be produced in a
similar manner to Example 1. The last distillation step can be
modified to meet a flash point of greater than 60.degree. C. and a
final boiling point less than 274.degree. C. Estimated properties
of the product from this modified fractionation are summarized in
Table 12.
TABLE-US-00015 TABLE 12 Physical properties of SK produced with
modified fractionation Distillation Initial BP (C.) 180 Temp @ 10%
Rec. (C.) 189 Temp @ 20% Rec. (C.) 197 Temp @ 50% Rec. (C.) 215
Temp @ 90% Rec. (C.) 251 Final BP (C.) 270 Flash Point (C.) 60
Density, 15 C. (kg/m.sup.3) 828
Example 5
Rocket Fuel Blends
[0147] Liquid kerosene rocket fuel blends can be produced using
cyclo-paraffinic kerosene (SK) from Example 1 and Example 4 and
commercially available kerosene range hydrocarbon component
ShellSol.TM. D60, D70, D90S and D100S as indicated below. These
liquid rocket fuel blends, their indicated blend ratios and their
properties are summarized in Table 13. Remainder of vol. % is the
respective ShellSol components.
TABLE-US-00016 TABLE 13-1 Key Specification Properties of Example
Series 5 using Example 1 SK content from Example 1 in respective
ShellSol blend (vol. %) 62 37 72 ShellSol .TM. Series D70 D60 D100S
Test ASTM Method Property Initial Boiling Point (.degree. C.)
Distillation 175 180 180 Final Boiling Point (.degree. C.)
Distillation 265 234 274 Flash Point (.degree. C.) D56 .gtoreq.60
.gtoreq.60 .gtoreq.60 Density at 15.degree. C. (kg/m.sup.3) D4052
805 803 808 Freezing Point (.degree. C.) D5972 <-51 <-51
<-51 Viscosity@-34.degree. C. (cSt) D445 est. 9.5 est. 8.5 est.
11 Hydrogen Content (mass %) D5291 est. 14.3 est. 14.3 est. 14.3
Net Heat of Combustion or D3338 or calculated est. 43.9 est. 44.4
est. 43.8 Gravimetric Energy Density (MJ/kg)
TABLE-US-00017 TABLE 13-2 Key Specification Properties of Example
Series 5 using Example 4 SK content from Example 4 in respective
ShellSol blend (vol. %) 79 74 62 37 ShellSol .TM. Series D100S D90S
D70 D60 Test ASTM Method Property Flash Point (.degree. C.) D56
.gtoreq.60 .gtoreq.60 .gtoreq.60 .gtoreq.60 Density at 15.degree.
C. (kg/m.sup.3) D4052 821 819 815 809 Freezing Point (.degree. C.)
D5972 <-51 <-51 <-51 <-51 Viscosity@-34.degree. C.
(cSt) D445 est. 14 est. 13 est. 12.3 est. 10.5 Hydrogen Content
(mass %) D5291 .gtoreq.13.8 .gtoreq.13.8 .gtoreq.13.8 .gtoreq.13.8
Net Heat of Combustion or D3338 or calculated .gtoreq.43.03
.gtoreq.43.03 .gtoreq.43.03 .gtoreq.43.03 Gravimetric Energy
Density (MJ/kg)
[0148] It is expected that the above blends will meet the RP rocket
fuel specifications.
Example 6
Proven Rocket Fuel Blend
[0149] Using the SK with modified fractionation as per Example 4
and the ShellSol D60 hydrocarbon component, a proven rocket fuel
blend was produced and assessed for applicability in relation to
the RP-1/RP-2 rocket fuel (MIL-DTL-25576) specification. The proven
rocket fuel blend was tuned to meet the required limits of the
MIL-DTL-25576 specification as shown in results Table 14 below. The
proven rocket fuel blend disclosed here relates to a 90% ShellSol
D60 and 10% SK with modified fractionation (Example 4) blend, by
volume.
TABLE-US-00018 TABLE 14 Specification data from the proven rocket
fuel blend of 90% ShellSol D60/10% SK (Example 4) (by volume) as
compared to the MIL-DTL-25576 (RP-1/RP-2) specification Proven ASTM
RP-1/RP-2 Rocket Method Specification Fuel Blend Initial Boiling
Point (deg. C.) D86 Report 182 10% Boiling Point (deg. C.) 185-210
191.9 50% Boiling Point (deg. C.) Report 197.3 90% Boiling Point
(deg. C.) Report 209.8 Final Boiling Point (deg. C.) 274 max 233.9
Flash Point (deg. C.) D56 60 min 60 Density @ 15 C. (g/cm3) D4052
0.799-0.815 0.8126 Freeze point (deg. C.) D5972 -51.1 max <-80
Viscosity @ -34 C. (cSt) D445 16.5 max 7.759 Gravimetric Energy
Calculated 43.03 min 43.407 Density (MJ/kg) (D3338)
[0150] Table 14 therefore shows that this proven rocket fuel blend
is viable in relation to the specification. Of additional interest
is how this proven rocket fuel blend compares against typical
values for an RP-1 and/or RP-2 rocket fuel. Typical values for
these rocket fuels were determined through independent testing of
commercially available rocket fuel, and are shown in Table 15.
TABLE-US-00019 TABLE 15 Typical RP-1/RP-2 Rocket Fuel (from
commercially available sources) specification values RP-1/RP-2
Typical Typical ASTM Method Specification RP-1 RP-2 Initial Boiling
Point (deg. C.) D86 Report 185 182.1 10% Boiling Point (deg. C.)
185-210 198.1 198.1 50% Boiling Point (deg. C.) Report 210.5 216.1
90% Boiling Point (deg. C.) Report 230.8 244.3 Final Boiling Point
(deg. C.) 274 max 247.1 261.9 Flash Point (deg. C.) D56 .sup. 60
min 63 62 Density @ 15 C. (g/cm3) D4052 0.799-0.815 0.8096 0.8142
Freeze point (deg. C.) D5972 -51.1 max <-80 <-80 Viscosity @
-34 C. (cSt) D445 16.5 max 10.90 12.14 Gravimetric Energy Density
(MJ/kg) Calculated (D3338) 43.03 min .sup. 43.483 43.449
[0151] Comparing and contrasting the results from the proven rocket
fuel blend (Table 14) and the typical values presented in Table 15
the values are all similar except for the viscosity at -34 C (ASTM
method D445). In particular, the gravimetric energy density differs
by no more than 0.2% between RP-1/RP-2/proven rocket fuel blend,
indicating that the specific impulse (the key parameter in rocketry
which determines the effective payload that can be launched for a
given quantity of propellant) should be consistent between the two
base-case fuels (RP-1 and RP-2) and the proven rocket fuel blend.
The specific impulse is a measure of the pounds of thrust produced
by the consumption of one pound of propellant in the timeframe of
one second, and is directly related to the square of the exhaust
velocity of the exit gases from the rocket engine. It is common
knowledge in the industry that the square of the exhaust velocity
of the exit gases is (approximately) proportional to the
temperature within the combustion chamber (in turn related to the
fuel energy density) and inversely proportional to the molar mass
of the exit gases: since both fuels are hydrocarbon-based with
similar densities/hydrogen content the exit gas molar mass should
also be similar. This logic points towards similar specific impulse
between rocket fuels RP-1, RP-2 and the proven rocket fuel
blend.
[0152] The proven rocket fuel blend does provide a distinct
advantage over the RP-1 and RP-2 fuels due to the lower viscosity
profile at sub-zero temperatures. This is particularly beneficial
on rockets that actively cool their fuel to get higher fuel
densities allowing more fuel mass to be contained within a given
fuel tank. Current practice for active onboard rocket fuel cooling
is limited by the higher viscosities experienced as the fuel is
cooled, negatively affecting the fuel's ability to flow and
critically to disperse effectively into the oxidizer through the
spray-forming hardware. Fuels with lower viscosities at sub-zero
temperatures can therefore be further cooled, maximizing the
benefit of improved fuel densities at lower active fuel cooling
temperatures.
[0153] Table 16 shows the sub-zero viscosities for two independent
temperatures for RP-1, RP-2 and the proven rocket fuel blend. FIG.
5 shows the same data graphically, the benefit of working with
lower viscosity fuels on rockets with actively cooled fuel tanks
being that they can be cooled to lower temperatures for a given
limiting fuel viscosity. FIG. 5 is a graphical representation of
data from Table 15; highlighting that for a given limiting
viscosity a lower temperature viscosity profile is beneficial to
allow for additional active fuel cooling to maximize fuel
density.
TABLE-US-00020 TABLE 15 Sub-Zero temperature viscosity data for the
base-case rocket fuels RP-1, RP-2 and the proven rocket fuel (RF)
blend Viscosity (cSt) -20 C. -34 C. RP-1 6.22 10.90 RP-2 6.97 12.14
Proven RF Blend 4.76 7.76
* * * * *