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AU661604B2 - Endothermic fuel additive to inhibit catalyst coking - Google Patents
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AU661604B2 - Endothermic fuel additive to inhibit catalyst coking - Google Patents

Endothermic fuel additive to inhibit catalyst coking Download PDF

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Publication number
AU661604B2
AU661604B2 AU44486/93A AU4448693A AU661604B2 AU 661604 B2 AU661604 B2 AU 661604B2 AU 44486/93 A AU44486/93 A AU 44486/93A AU 4448693 A AU4448693 A AU 4448693A AU 661604 B2 AU661604 B2 AU 661604B2
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Australia
Prior art keywords
fuel
endothermic
fuel mixture
coking
reactor
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AU44486/93A
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AU4448693A (en
Inventor
George Albert Coffinberry
Michael Jay Epstein
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General Electric Co
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General Electric Co
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Description

Our Ref: 470580 4 604 P/00/011 Regulation 3:2
AUSTRALIA
Patents Act 1990
ORIGINAL
COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): General Electric Company One River Road SCHENECTADY New York 12345 UNITED STATES OF AMERICA DAVIES COLLISON CAVE Patent Trade Mark Attorneys '.evel 10, 10 Barrack Street SYDNEY NSW 2000 Address for Service: Invention Title: Endothermic fuel additive to inhibit catalyst coking The following statement is a full description of this invention, including the best method of performing it known to me:- 5020 DV10324
PATENT
13DV-10324 ENDOTHERMIC FUEL ADDITIVE TO INHIBIT CATALYST COKING BACKGROUND OF THE INVENTION Field of the Invention This invention relates to fuel additives to inhibit coking of catalysts used with endothermic hydrocarbon fuels in propulsion systems with particular application to high speed aircraft. More particularly the present invention provides compositions and methods for avoiding thermally induced fuel deposits on the catalytic surfaces of combination reactor heat exchangers which are used to catalytically dehydrogenate endothermic hydrocarbon fuels to provide a heat sink for cooling high speed aircraft systems.
Description of Related Art It is well known to design aircraft propulsion systems to use endothermic hydrocarbon fuels.
Endothermic fuels hold the potential for significantly increasing the performance of gas turbine and other engines as a result of their heat sink potential. One 20 particularly important endothermic hydrocarbon fuel is Methylcyclohexane (MCH) which can be catalytically *converted to toluene and hydrogen with a theoretical absorption of 1959 Btu/lbm. This example includes both the sensible and chemical absorption of heat and assumes 25 a 99% conversion and that the fuel was heated from to 1340* F.
a *l u DV10324 PATENT 13DV-10324 2 An example of this application may be found in U.S.
Patent No. 3,739,581, entitled "Method And Apparatus For Providing Jet Propelled Vehicles With A Heat Sink", by Eliyahu Talmour, .wherein use is made in a jet propelled vehicle of the catalytic reforming of a hydrocarbon with steam and carbon dioxide, as supplied by the exhaust from the afterburner of the jet engine. This technology may be used to generate heat sink capacities of the order of 6,000 BTU per pound of the fuel, e.g. methane, which is combined with the exhaust gases for passage -o the reforming zone, or zones, which serve the desired heat sink function. The heat sink provided by the reforming zone can be utilized to take up heat from any desired points in the vehicle including the engine, wing surfaces, or the like, using direct or indirect methods of heat exchange.
The practical implementation of converting MCH to toluene and hydrogen requires the use of a heterogeneous catalyst. Reforming catalysts conventionally used in the conversion of petroleum naphtha feedstocks to high octane gasoline are also used in the present invention.
i These catalysts essentially dehydrogenate cyclo paraffinic reactants to produce the desired result.
Such catalysts include, but are not limited to Pt-A1 2 0 3 Pt-Re-Al03, and Pt-Ir-Al 2 0 3 Over the range of temperatures and pressures in which these reactions typically occur (400"-900' K and 1 to 150 atmospheres) competing reactions take place which include cracking, o re-hydrogenation, and coke formation. The formation of 30 coke in particular, is a problem as it tends to strongly "o adsorb on the surface of the catalyst, fouling active sites and reducing catalyst surface area and pore
I
IIl s DV10324
PATENT
13DV-10324 3 passages, thereby reducing overall catalytic activity.
Very high purity MCH fuel is required to avoid formation of deposits which can poison the metal catalyst which is.needed to accelerate the endothermic conversion of MCH to toluene and hydrogen. The purist grade of commerc3ally available MCH (C 7
H
14 having a greater than 99% purity, typically contains about 0.4% dimethycyclopentane isomer. Even with 100% purity, MCH catalytic dehydrogenation with Pt. on A1 2 0 3 substrate produces significant byproducts of dimethylcyclopentanes and dimethylcyclopentane isomers. This occurs because the desired dehydrogenation reaction; (MCH) CH 14 (Toluene) C 7 Hg 3H 2 is in competition (via the A1 2 0 3 with isomerization reactions such as; (MCH) CM 1 4 (ethylcyclopentane) C 7
H
4 or (MCH) C7H 14 (dimethylcyclopentane) CH 14 These byproducts are then partly dehydrogenated to cyclopentadienes, which then polymerize to form 20 poisoning deposits in the form of coke on the catalyst.
Therefore there is a need to inhibit the coke formation on the catalytic surfaces in the reactor portion of heat exchangers that make use of the cooling and heat sink capacity of endothermic hydrocarbon fuels such as MCH.
25 U.S. Patent No. 3,263,414 entitled "Endothermic Reactions For Cooling and providing Fuel In Supersonic Combustion" by Walter A. Herbst discloses a fuel additive and method of using the fuel additive to overcome the problems associated with and caused by luminous flames in combustors burning endothermic reaction products by adding to the full stream entering the combustor, at a point between the position where the ~CF -s II I I 1 I DV10324 PATENT 13DV-10324 4 endothermic chemical reaction takes place and the combustor, a suitable combustion promoter.
Methylcyclohexane is one of the fuels suggested for use with the combustion promoters by Herbst. However the benefit afforded by this technology cannot help the reactor heat exchanger inhibit coking because Herbst teaches adding the fuel additive after the fuel has passed through the reactor which is exactly the opposite of what the present invention teaches.
SUMMARY OF THE INVENTION The present invention provides compounds, apparatuses, and methods involving the fuel supply of a combustion system that uses a heat exchanger as a reactor to catalytically dehydrogenate a suitable endothermic hydrocarbon fuel. The invention provides an endothermic hydrocarbon fuel and fuel supply with an anti-coking fuel additive. The anti-coking fuel additive comprises a minute quantity of nitrogen containing compound preferably an organic amine such as cyclohexylamine (C 6
HONH
2 wherein the fuel mixture has S•an amount of the nitrogen containing compound such that there is less than by weight nitrogen. Preferably the cyclohexylamine is added to the liquid MCH to form a fuel mixture which can be stored and inhibits catalyst 25 deterioration wherein the fuel mixture including the cyclohexylamine has an amount of cyclohexylamine such that nitrogen comprises about 0.035% by weight or 50 ppm of the fuel mixture. The nitrogen compound will inhibit isomerization reactions as it is rapidly converted to.
30 armonia, which then neutralizes (poisons) the acid sites which are characteristic of the Al203 substrate of the I DV10324 PATENT 13DV-10324 5 catalyst and prevents coking at the site.
ADVANTAGES
Among the advantages provided by the present invention is that the fuel mixture including the nitrogen containing compound inhibits the amount of coke formation on the surface of the catalyst within the reactor. As a result, catalytic activity does not degrade as quickly and the combustion system and propulsion system is more economical to maintain and operate.
The present invention allows construction of smaller and lighter weight reactors because it inhibits coke formation on the reactor catalytic surfaces that would otherwise decrease its effectiveness more quickly.
The present invention provides a more durable longer lasting endothermic fuel reactor and combustion system which is ultimately less expensive to operate and more commercially feasible than similar combustor systems presently contemplated.
C" 20 BRIEF DESCRIPTION OF THE DRAWINGS The foregoing aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawing where: FIG. 1 is a schematic view of a combustor system in accordance with one embodiment of the present invention.
o DETAILED DESCRIPTION OF THE INVENTION Schematically illustrated in FIG. 1 is an aircraft gas turbine engine combustion system, generally shown at 10, for use with endothermic fuels such as MCH and which 111 may be used other types of propulsion engines such as a rocket engine. The combustion system 10 has an endothermic hydrocarbon fuel mixture supply 12 wherein the fuel mixture preferably includes MCH as the fuel mixed together with the anti-coking fuel additive of the present invention. The anti-coking fuel additive comprises a minute quantity of a nitrogen containing compound which inhibits coke formation on the surface Pt. based catalysts. The fuel mixture including the nitrogen containing compound comprises less than by weight nitrogen. The nitrogen containing compound is preferably an organic amine like cyclohexylamine (C 6 HoNI-I 2 and the fuel mixture of MCH and the amount of cyclohexylamine preferably is such that nitrogen comprises about 0.035% by weight or 50 ppm of the fuel mixture.
S. 'A pump 14 which pumps the fuel mixture through metering and throttle valves 0 18. The fuel flow is split at 24 and a first portion of the fuel flow is bypassed around S* 15 a catalytic reactor 40 and sent through a bypass line 26 directly to the engine's burner or combustor. The remaining fuel is directed through the reactor fuel line branch 28. This remaining fuel will serves as catalytic reactor feed in order to make use of its cooling :i sink capability. The remaining fuel is passed through a preheater 30 then to a catalytic o 0 reactor 40. The reactor 40 converts the MCH into its reaction products (toluene 20 hydrogen), an endothermic reaction which absorbs heat and provides the heat sink for the heat exchanger function of the reactor 40. The fuel additive of the present invention inhibits the coke formation on the surface of the Pt catalyst used in the rector p:\wpdocs\ad47058O.gcfAjc le "I L- I~YUI11(1111 -7- The product flow from the catalytic reactor 40 is sent to the burner through a second fuel line 48 to be combusted with the first portion of fuel from the bypass line 26.
Methylcyclohexane is catalytically converted to toluene and hydrogen with a theoretical absorption of 1959 Btu/lbm which includes both the sensible and chemical absorption of heat and assumes a 99% conversion and that the fuel was heated from 7G°F to 1340 0
F.
This reaction in reactor 40 allows the reactor to be used as a heat exchanger to cool parts of an aircraft (not shown).
s e o 0 p:\wpdocs\amd\470580.gcn\ajc s I-

Claims (17)

1. An endothermic fuel mixture comprising: an endothermic hydrocarbon fuel that can be catalytically dehydrogenated to provide a heat sink and an anti-coking fuel additive comprising a minute quantity of a nitrogen containing compound such that the fuel mixture is suitable as a heat sink when used as a feedstock in a catalytic reactor that is used as a heat exchanger.
2. An endothermic fuel mixture as claimed in claim 1 wherein said fuel is Methylcyclohexane.
3. An endothermic fuel mixture as claimed in claim 2 wherein said anti-coking fuel additive comprises an organic amine.
4. An endothermic fuel mixture as claimed in claim 3 wherein said organic amine is cyclohexylamine.
An endothermic fuel mixture as claimed in claim 4 wherein said fuel mixture contains nitrogen in an amount less than by weight.
6. An endothermic fuel mixture as claimed in claim 4 wherein said fuel mixture contains nitrogen in an amount about .035% by weight. p:\wpdocs\amd\470580.gcn\ajc -9-
7. An endothermic fuel system for a propulsion engine, said endothermic fuel system comprising: a fuel supply means for supplying a fuel mixture that includes an endothermic hydrocarbon fuel that can be catalytically dehydrogenated to provide a heat sink, a catalytic reactor that is used as a heat exchanger and is operably connected to said fuel supply so as to be able to receive at least a portion of said fuel mixture from said endothermic fuel supply during engine operation to be used as feedstock for said reactor, and said fuel mixture having an anti-coking fuel additive which comprises a minute quantity of nitrogen containing compound.
8. An endothermic fuel system as claimed in claim 7 wherein said fuel is Methylcyclohexane. *1 15
9. An endothermic fuel system as claimed in claim 8 wherein said anti-coking fuel additive comprises an organic amine.
10. An endothermic fuel system as claimed in claim 9 wherein said organic amine is cyclohexylamine.
11. An endothermic fuel system as claimed in claim 10 wherein said fuel mixture contains nitrogen in an amount of about .035% by weight. Slp: \wpdocs\amd\470580. .gcn\aje
12. A cooling method for providing a heat sink for cooling a high speed aircraft, said method comprising the following steps: a) supplying at least a portion of an endothermic hydrocarbon fuel mixture to a heat exchanger that is operated as a catalytic reactor, said portion of endothermic hydrocarbon fuel being used as a feedstock in the reactor and wherein the fuel mixture includes an anti-coking fuel additive which comprises a minute quantity of nitrogen containing compound, b) reacting the feedstock in the reactor to catalytically dehydrorfnate the hydrocarbon fuel in the hydrocarbon fuel mixture to provide a heat sink for the heat exchanger, and c) supplying the products of the reaction in the catalytic reactor to a burner where it is combusted.
13. A cooling method as claimed in claim 12 wherein the fuel is Methylcyclohexane. t
14. A cooling method as claimed in claim 13 wherein the anti-coking fuel additive comprises an organic amine.
15. A cooling method as claimed in claim 14 wherein the organic amine is cyclohexylamine. i
16. A cooling method as claimed in claim 15 wherein the fuel mixture contains nitrogen in an amount of about .035% by weight. p:\wpdocs\amid\470580.gcii\ajc 11
17. A fuel mixture substantially as hereinbefore described with reference to the drawing. DATED this 18th day of April, 1995 GENERAL ELECTRIC COMPANY By Its Patent Attorneys DAVIES COLLISON CAVE 0 no. kk/~ fA~') 1):\wpdrcS\ntnJ\id470580.gcn\~jc ~I C I- I La 0 DV10324 PATENT 13DV-10324 ABSTRACT The present invention provides compounds, apparatuses, and methods involving the fuel supply of a combustion system.that uses a heat exchanger as a reactor to catalytically dehydrogenate a suitable endothermic hydrocarbon fuel. The invention provides an endothermic hydrocarbon fuel and fuel supply with an anti-coking fuel additive. The anti-coking fuel additive comprises a minute quantity of nitrogen containing compound preferably an organic amine such as cyclohexylamine wherein the fuel mixture has an amount of the nitrogen containing compound such that there is less than by weight nitrogen. *o6o* *o I I
AU44486/93A 1992-08-17 1993-08-05 Endothermic fuel additive to inhibit catalyst coking Ceased AU661604B2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US93014092A 1992-08-17 1992-08-17
US930140 1992-08-17

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AU4448693A AU4448693A (en) 1994-02-24
AU661604B2 true AU661604B2 (en) 1995-07-27

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102351797B (en) * 2011-09-26 2014-06-11 无锡美华化工有限公司 Production device and method of hydantoin
CN104059697B (en) * 2014-06-23 2016-01-20 浙江大学 There is high heat sink hydrocarbon fuel composition

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4040799A (en) * 1974-10-07 1977-08-09 Petrolite Corporation Cyclohexlamines used as fuel additives
US4623363A (en) * 1985-11-27 1986-11-18 Ethyl Corporation Fuel compositions
US4773652A (en) * 1987-04-20 1988-09-27 Mosser Kenneth J Automatic reset target assembly

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0476196B1 (en) * 1990-09-20 1993-11-18 Ethyl Petroleum Additives Limited Hydrocarbonaceous fuel compositions and additives therefor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4040799A (en) * 1974-10-07 1977-08-09 Petrolite Corporation Cyclohexlamines used as fuel additives
US4623363A (en) * 1985-11-27 1986-11-18 Ethyl Corporation Fuel compositions
US4773652A (en) * 1987-04-20 1988-09-27 Mosser Kenneth J Automatic reset target assembly

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JPH06172761A (en) 1994-06-21
JP2511637B2 (en) 1996-07-03
AU4448693A (en) 1994-02-24

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