CA2062024A1 - Fluid containment article for hot hydrocarbon fluid and method of preventing fuel thermal decomposition deposits - Google Patents
Fluid containment article for hot hydrocarbon fluid and method of preventing fuel thermal decomposition depositsInfo
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- CA2062024A1 CA2062024A1 CA002062024A CA2062024A CA2062024A1 CA 2062024 A1 CA2062024 A1 CA 2062024A1 CA 002062024 A CA002062024 A CA 002062024A CA 2062024 A CA2062024 A CA 2062024A CA 2062024 A1 CA2062024 A1 CA 2062024A1
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- Prior art keywords
- fluid
- diffusion barrier
- hydrocarbon
- catalytically
- fuel
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/60—Efficient propulsion technologies, e.g. for aircraft
Abstract
Dkt. No. 13-DV-10367 ABSTRACT OF THE DISCLOSURE
Fluid containment article for hot hydrocarbon fluid wherein the surface for contacting the fluid is a diffusion barrier material coated on a substrate. The diffusion barrier layer is either catalytically-inactive and inhibits the formation of hydrocarbon thermal decomposition products in the fluid or catalytically-active and promotes the formation of a loosely adherent coke in the fluid while inhibiting the formation of other thermal decomposition products in the fluid. Preferred catalytically-active and catalytically-inactive diffusion barrier materials are amorphous metal oxides, such as zirconium oxide and tantalum oxide respectively, deposited as a liner on the surface of a metal substrate. The fluid containment articles find utility in components subjected to high temperatures and using hydrocarbon fluids without additives, without special attention to quality control and without the need for special processing.
Fluid containment article for hot hydrocarbon fluid wherein the surface for contacting the fluid is a diffusion barrier material coated on a substrate. The diffusion barrier layer is either catalytically-inactive and inhibits the formation of hydrocarbon thermal decomposition products in the fluid or catalytically-active and promotes the formation of a loosely adherent coke in the fluid while inhibiting the formation of other thermal decomposition products in the fluid. Preferred catalytically-active and catalytically-inactive diffusion barrier materials are amorphous metal oxides, such as zirconium oxide and tantalum oxide respectively, deposited as a liner on the surface of a metal substrate. The fluid containment articles find utility in components subjected to high temperatures and using hydrocarbon fluids without additives, without special attention to quality control and without the need for special processing.
Description
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-1- Dkt. No. 13-DV-10357 FLUID CONTAINMENT ~RTICLE FOR HOT HYDROCARBON
FLUID ~ND METHOD OF PREVENTING FUEL
THERMAL DECOMPOSITION DEPOSITS
Inventor: George A. Coffinberry BACKGROUND OF THE INVENTION
The present invention relates generally ~o deposits formed on surfaces in contact with hydrocarbon fluids, and more particula:rly, to a method o~ preventing or reducing the deposit of hydrocarbon fluid thermal decomposition products on surfaces in contact therewith and to a fluid containment article having a surface which inhibits the formation of gum, coke, sulfur compounds and/or other impurities formed by thermal decomposition of the fluid, without resorting to modification of the fluid, without adoption of special procedures and without installation of special equipment for ehelr use.
Because high temperature is usually associated with undesirable levels;of hydrocarbon fluid dep~sit for~ati~n, the ~15 technical subject herein is~customarily referred to as thermal : instability, or in:the:case of fuels, as fuel instability.
The mechanisms for formation of deposits ~rom thermal instability have been studied and documented. In the case of fuels, it is generally accepted that there are two distinct , . . . :
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Dkt. No. 13 DV-10367 mechanisms occurring at two levels of temperature. In the first mechanism, referred to as the coking process, as temperature increases from room temperature, there is generally a consistent increase in the rate of formation of coke deposits up to about 1200F where high levels of hydrocarbon pyrolysis lead to coke formation and eventually limit the usefulness of the fuel. A second lower temperature mechanism generally peaks at about 700F and involves the formation of gum deposits. This second mechanism is generally better understood than the coking process. It involYes oxidation reactions which lead to polymerization which includes the formation of gums. Both coke and gum formation and deposits can occur simultaneously in the mid-temperature region.
Co)ce formation in hydrocarbons is discussed in U.S.
Patent No. 2,698,512, and heat stab:ility of jet fuel and the consequences of thermal degradation of the fuel are discussed in U.S. Patent No. 2,959,915, both patents being incorporated herein by reference in their entire1:y. These patents suggest specific formulations which place limitations on the fuel chemistry and impurities associated with hydrocarbon fuels so that the fuels will be usable at high temperatures without the typical formation of gums and coke.
Gum and coke formation are discussed in U~S. Pat~nt No. 3,173/247, which is incorporated by referance herein in its entirety. It is indicated therein that t very high flight speeds, heat must be transferred, particularly from the engine, to some part of the flight vehicle or to its load, and although the fuel which is stored on the vehicle, could serve to receive this heat, in practice, such procedure is unfeasible because jet ~uels are not stable to the high 2 ~
Dkt. No. 13-DV-10367 temperatures which are developed at multi-Mach speeds, instead, they decompose to produce intolerable amounts of insoluble gum or other deposits, for example coke. As with the previously referenced patents, the solution to the problem has been directed toward limitations on fuel ch~mistry and impurities associated with the fuel.
Even with the most elaborate special treatment of the fuel, coke ~ormation cannot be entirely eliminated even when a pure hydrocarbon is used because if the temperature is high enough and the time is long enough, coke formation will occur. On the other hand, the chemistry of the hydrocarbon fluid mixture and the chemistry of the containment vessel can have a major influence on deposit mechanisms and deposit rates at the temperatures where it is most desirable to use the ~luid. In the lower temperature region where gum formation occurs, oxygen from air dissolved in the liquid is the major adverse ingredient. Boiling amplifiles this adversity because of the oxygen concentration effect of gas bubbles adjacent to hot walls. If oxygen or air is absent, gum formati~n is not likely to occur.
In much of the prior art, the problems associated with gum and coke thermal deposits has predominatPly dealt with bulk fluid chemistry and reactions which can take place within the fluid. These investigations have involved a wide range of hydrocarbon compositions and the presence of numerous impurities such as sulfur compounds, nitrogen compounds, oxygen and trace metals. It has been obserYed that deposits attached to containment walls often contain very large quantities of sulfur and nitro~en compounds or intermediates thereof in addition to gums and cokes. Little attention has, however, been given in the prior art to the role o~ the 2~2~2~
Dkt. No. 13-DV-10367 ~4-chemistry and reactions which directly take place between the containment walls and the fluid.
-Even though wall reactions are not well understood, it can be generally supposed thak fluid-wall deposit thickness reactions might be reduced if the wall were coated with some form of relatively inert material; for example, porcelain or glass coatings are often used to generally prev~nt deposit on such common items as stoves and water tanks. These coatings are, however, not structurally suitable for the application envisioned by the present invention. Other inert non-sticking coatings include such polymers as Teflon, but these materials are not suitable at the high temperatures under consideration.
In U.S. Patent No. 3,157,990, certain phosphate additives are added to the monopropellant wherein the phosphates decompose in the reaction chamber and form a coating, probably a phosphate coating, on the internal generator surfaces, and it is suggested that this coating effectively inhibits carbon decomposition and scaling. In U.S. Patent No. 3,236,046, which is incorporated by reference herein in its entirety, the i~terior surfaces of stainless steel gas generators are passivated ~with sulfurous materials to overcome deposition of coke o~ the ~urfaces of the gas generator, and passi~ation is defined as a pretreatment which sub~tantially reduces initial cataly-tic coke ~o~mation. From these pàt~nts, it is deduced that the coke inhibiting mechanisms is in fact a passivation process in which the phosphate or ~ulfur reacts with ~he wall in much the same way as oxygen reacts with iron or copper to form oxides which protect the wall from further reaction. Ordinarily red oxide paint primer is a similarly well-known approach. The patents are suggestive that some ~orm o~ r~action takes ~lace between the fuel and the wall.
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Dkt. No. 13~DV-10367 In U.S. Patent No. 4,078,604, which is incorporated by reference herein in its entirety, heat exchangers are characterized by thin-walled corrosion resistant layers of electro-deposited gold or similar corrosion-resistant metals on the walls of the cooling channels within the inner wall, and the cooling ohannels are covered with the electro-deposited layer of gold in order to make the surfaces corrosion resistant to such storable liquid fuels as red fuming nitric acid. In this prior art case, the wall is protected from corrosion by the propellent, but the intent is not to prevent deposit formations. It is also known from prior art that gold plating has been used to prevent surface catalytic reactions with fuel in which case the objective is not to interfere with gum formation for the purpose of evaluatin~ fuel chemical stability.
Thermal instability and fuel instability, referred to above, are becoming more significant with developing technology, and it will become ~ven more significant as processes and machinery will be required to operate at higher temperatures as afforded by advances in materials technology and as the chemical quality of hydrocarbons for fuels, oils, lubricants, petrochemical processes (plastics and synthetics) and the like, decreases. Furthermore, hydrocarbon fluids, ~5 fuels and oils deri~ed ~rom non-petroleum sources, such as shale and coal, will have significantly more problems with thermal instability because of their high content of olefins, sulfur and other compounds. Accordingly, it i5 advantageous to provide fluid containment articles and processes for preventing the ~ormation of adverse decomposition products and foulants in such applications where thermal instability, including fuel ins~ability, is a problem as a result of exposure to such fluids to high temperatures.
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Dkt. No. 13-DV-10367 In view of the foregoing, it can be seen that it would be desirable to provide fuel containment articles for containing hot hydrocarbon fluid in which decomposition products formed by thermal decomposition of the hydrocarbon fluid is avoided, eliminated or reducedO It would also be desirable to provide a method of protecting metal surfaces which contact hot hydrocarbon fluid, from the deposit of decomposition products of the hydrocarbon fluid. It can also be seen from the foregoing that it is desirable to provide methods and articles for use with hydrocarbon fuels wherein the hydrocarbon fuel can be used as a heat sink without the undesirable deposit of insoluble gums, coke, sulfur compounds or mixtures thereof on containment surfaces. It is also desirable to provide methods and articles for containment of vaporized fuel to reduce NOX emission and to provide methods and articles for containment of low quality fuels derived from coal, shale and low grade crude oil.
The disadvantages of the prior art processes and techniques discussed above involve the need to alter the hydrocarbon chemistry, maintain strict control of impurities and/or provide additives and special processing such as passivation treatments. All of these techniques constrain the use of the fluid, increase cost and promote uncertainty as to the ~uality level of the ~uel or treatment at a particular time. The present invention overcomes all of these limitation~ by providing a method and articles which eliminate or reduce the surface reactions which lead to formation of thermal instability deposits from hydrocarbon fluids and which eliminate or reduce adherence o~ deposits on sur~aces using ordinary low-cost fuels, oils and other hydrocarbons without :~
focusing special attention to impurities or quality.
Furthermore, there are a multitude of processes, systems and . ~ : ,, . . . , --. . .: . ~ .
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Dkt. No. 13-DV-10367 devices including petrochemical processes, machine tools, automobile engines, aircraft gas turbine engines, and marine and industrial engines in which surface deposits from hydrocarbon fluids, fuels and oils are a major problem.
Deposits can foul heat exchangers, plug fuel injectors and lubrication distribution jets, jam control valve and cause problems with many other types of operating and control devices associated with hydrocarbon fluids, fuels and oils.
It is a primary objective of this invention to overcome these disadvantages.
SUMMARY OF THE INVENTION
These and other disadvantages are overcome in lS accordance with the present invention by providing a coating, hereinafter referred to as a liner, liner material, diffusion barrier or diffusion barriex material on ~ fluid containment metal surface, also referred to here:in as a substrate.
In accordance with the present invention, there is provided a method and articles for preventing the deposit of decomposition products and/or therma:L instability deposits from hot hydrocarbon fluids on a metal substrate, and metal surfaces are protected from the deposit of hydrocarbon fluid decomposition products resulting from thermal decomposition of hot hydrocarbon fluid in a fluid containment article or system carrying hot hydrocarbon fluid. Thus, for example, as a result of the present invention, heat generated by combustion of fu~l in the operation of a combustor which utilizes hydrocarbon fuel, or heat from other sources, can be transferred by heat exchange principles to hydrocarbon fuel without the undesirabl~ thermal decomposition of the fuel and the subseguent deposit of thermal decomposition products on the walls of the articles containing the fuel.
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Dkt. No. 13-DV-10367 In one aspect of the present invention, there is provided a fluid containment article for containing hot hydrocarbon fluid comprising a substrate having a surface adapted for contact with the hydrocarbon fluid wherein the surface comprises a liner selected from the group consisting of a catalytically-active diffusion barrier material which catalyzes thermal decomposition in the hydrocar~on fluid to promote the formation of coke, the coke being subs-tantially non-adherent to the liner, and a ca~alytically-inactive diffusion barrier mat~rial which is inert to thermal decomposition in th~ hydrocarbon fluid and inhibits the formation of coke, the catalytically-active and catalytically-inactive diffusion barrier materials inhibiting the *ormation of gum, sulfur compounds or other decomposition impurities or mixtures thereof formed by thermal decomposition of the hydrocarbon ~luid, the liner material being a physical diffusion barrier located between the substrate and hydrocarbon fluido In another aspect of the present invention, there is provided a method of preventing the deposit of thermal decomposition products in a hydrocarbon fluid on a metal surface of a device adapted to contain the hydrocarbon fluid I ~:
comprising applying to the metal surface a layer o~ diffusion ~, barrier material which is inert to chemical formation o~
thermal decomposition products in the fuel. In this embodiment of the invention, the liner or liner material itself is inert to chemical reaction with hydrocarbons and hydrocarbon impurities, that is, it is inert to the chemical 3Q formation of such thermal dPcomposition products as gum, co~e, '! ~ ' sulfur compounds and other decomposition impurities in the ~:
fluid. As used herein, the liner in this instance is a catalytically-inactive difusion barrier material.
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Dkt. No. 13-DV-10367 _g_ In still another aspect of the present invention, the deposit of thermal decomposition products in a hydrocarbon fluid on a metal surface of a device adapted to contain the hydrocarbon fluid is prevented by applying to the metal surface a layer of diffusion barrier material which catalyzes thermal decomposition in the hydrocarbon fluid to promote the formation o~ coke, the diffusion barrier being a deterrent to the formation of gum and sulfur compounds. Thus, in this embodiment, the formation of coke, which is substantially non-adheren~ or loosely-adherent to the diffusion barrier material, is promoted while the formation of gum, sulfur compounds and other decomposition impurities is inhibited. In this embodiment of the invention the liner or liner material itself is a catalyst which accelerates or promotes the reaction of hydrocarbon and hydrocarbon impurity to beneficial products (coke) which do not adhere or tend not to adhere to the liner or liner material. The coke and any similar non-polymer products can be tolerated in fuel because they do not tend to adhere to surfaces, and they burn in the combustor along with the fuel. As used herein, the liner in this embodiment is a catalytically-active diffusion barrier material.
The coating material or liner material is deposited on a surface which is adapted for contact with a hydrocarbon fluid, for example a distillate fuel, and depending on khe particular material, it inhibits or prevents the formation of gum, coke, sulfur compounds, or other decomposition impurities or mixtures thereof formed by the thermal decomposition of the hydrocarbon fluid, or it catalyzes the formation of coke while inhibiting or preventing the formation o gum, sulfur compounds and other decomposition impurities. The coating or liner material is al~o a physical diffusion barrier to the hot 2~2~2~
Dkto No. 13-DV-10367 hydrocarbon fluid, that is, it will ~ot permit the diffusion of or pa~sing of the fluid through the material to the substrate on which the coating material is deposited. Thus, the liner material is a physical barrier located b~tween the substrate and the hydrocarbon fluid.
From the foregoing, it is evident that the present invention solves the problems related to the formation of gum, coke, sulfur and other deposit-forming reactions which are chemically associated with contact between hot hydrocarbon fluid and the materials which the fluid contacts, for ex~mple a wall. The present invention also solves the problems associated with the attachment or adherence of deposits to materials which the fluid contacts, by either physical or chemical means. In certain embodiments, the present invention also preferentially directs fluid-surface reactions toward deposits which tend not to adhere to materials which the fluid contacts.
Although there is no intention to be bound by any particular theory or explanation of t:he mechanism(s) by which the present invention inhibits the formation of gum, coke, ~-sul~ur compounds and other deposit-forming species which are ~ormed by thermal decomposition of hydrocarbon fluid, it is believed that chPmical reactlons ta~e place between specific atoms and compounds which are part of the substrate chemistry and react under the in~luence of temperature with hydrocarbons and hydrocarbon impuritles such as nitrogen, oxygen and sulfur and their compounds, to form metal nitrogen, metal oxygen and metal sulfur compounds. These metal compounds form deposits and/or precursors to deposits and provide an a tachment mechanism between the substrate and other deposits. This theory is supported by the argument that chemical-absorption 2 ~ 2 ~
Dkt. No. 13-DV-1036/
provides a much stronger surface bond than would simple physical absorption to the surface. In the specific case of -gum deposits, it is theorized that metal atoms and metal compounds in the substrate can react to form hydrocarbon radicals which are then highly susceptible to further reaction such as with oxygen, to lead ultimately to polymerization and gums. Substrate reactions can also provide chemistry which is known in the art to be precursors to gums, and after the precursors attach to the substrate, they become the means for which gums and cokes and other deposits can grow by means of chemic~l or physical means, to consequential proportions.
In accordance with the present invention, a liner material on the surface shields objectionable metal atoms and metal compounds in the substrate or wall from reaction with khe hydrocarbon fluid and its impurities. The same liner material also physically prevents or :inhibits diffusion of metal atoms and metal compounds into the hydrocarbon fluid.
The same liner material also prevents or inhibits diffusion of the ~ydrocarbon fluid and any impurities that it contains, to the substrate.
Two types of liner or liner materials may be used in the processes and fluid containment materials of the present invention. A first type of liner material is catalytically-inactive diffusion barrier material. A
catalytically-inactive diffusion barrier material is one which is inert to the formation of any decomposition products in hot hydrocarbon fluid which contacts it. Thus, when such a catalytically-inactive diffusion barrier material is used as the liner on a hydrocarbon fluid containment article adapted to contact hydrocarbon fluid, there is substantially no thermal decomposition of the hydrocarbon fluid at elevated ~2~4 Dkt. No. 13-DV-10367 --1~
temperatures, for example, up to 900F, and there is no gum, sulfur compound, coke or other decomposition impurity formation in the heated fluid.
A second type of liner material is catalytically-active diffusion barrier material. A
catalytically-active diffusion barrier material is one which actively permits or promotes the formation in hot hydrocarbon fluids of a compound or compounds which have no adverse effect on the utilization of the fuel, on the flow and transport of the fuel and/or on the components contacted by the fuel. More specifically, a catalytically-active diffusion barrier material is one which actively permits or promotes the formation of coke in the hot hydrocarbon fluid, a coke which remains substantially dispersed in the fluid as it flows and is transported through containment articles and other components and is ultimately burned, or otherwise utilized, with the fluid. Coke which is so formed and remains substantially dispersed in the fluid in which it is formed, is defined herein as loosely-adhered or substantially non-adherent coke because it tends not to stick to or adhere to containment walls and elements either by physical or chemical attraction. With the formation of coke in the presence of the catalytically-active diffusion barrier material is the simultaneous inhibition or repression of formation of gumj sulfur compounds and/or other decomposition impurities in the hydrocarbon fluid. In both types o~ liner material, the diffusion barrier material is also a physical barrier or obstacle located between:the substrat~ and the hydrocarbon fluid and prevents physical contact of the fluid and the substrate.
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Dkt. No. 13-DV-10367 13~
As used herein, the phrase 'iother decomposition impuritiesl' refers to any compounds which can form as a result of the thermal instability of a hydrocarbon fluid, other than gum, sulfur compounds and coke. The prior art and literature disclose many such species and can include, for example, metal-nitrogen compounds, metal-oxygen compounds, various olefins and/or pol~mers formed therefrom, saturated and unsaturated polymers, cyclic and aromatic hydrocarbon compounds and the like. The other decomposition impurities which can form in a hot hydrocarbon fuel are frequently dependent on the initial fuel content including the starting impurities therein.
BRIEF DESCRIPTION OF THE DRAUINGS
These and various other features and advantages of the invention can be best understood from the following description taken in conjunction with the accompanying drawings in which:
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Figure 1 is a partial longitudinal view of a high pressure turbine nozzle for a jet engine fueled by distillate fuel and incorporating the heat exchanger wall construction of the present invention~
Figure 2 is a sectional view taken along the line of II - II of Figure 1 showing fual conkainment passages for circulating distillate fuel.
Fi~ure 3 is a photograph of two (2) stainless steel planchettes showing before and after exposures to hot jet-A
fuel.
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- , ~ - ': ' ' ' ' 2 ~ 2 4 Dkt. No. 13-DV-10367 Figure 4 is a scanning electxon beam micrograph (magnified 2000X) of an uncoated area (prior to testing) of a planchetke which has been sand blasted~
Figure 5 is a scanning electron beam micrograph (magnified 5000X) of an uncoated area (after testing) of a planchette.
Figure 6 is a scanning electron beam micrograph ~;
(magnified 2000X) of a coated area (prior to testing~ of a planchette.
Figure 7 is a scanning electron beam micrograph (magnified 2000X) of a coated area (after testing) of a lS planchette.
DETAILED DESCRIPTION OF THE INVENTION
The terms hydrocarbon fluid, hydrocarbon fuel and distillate fuel ~ay be used interchangeably herein.
The invention has applicab:ility to any hydrocarbon fluid in which gum or other polymers, coke, sulfur compounds or any other decomposition impurities form when the fluid is exposed to heat. Although the invention i~ not directed to or limited by any particular hydrocarbon fluid or hydrocarbon fuel, typical ~uels for which the method and fluid containment articles of the present invention are adapted, and typical fu21s from which the substrates of fluid containment articles are protected in accordance with the present invention, are the hydrocarbon or distillate fuels generally discussed above and include hydrocarbons and distillation products thereof which are generally liquid at room temperature. The fluids '' -.
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Dkt. No. 13-DV-10367 may be pure hydrocarbon or mixtures of hydrocarbons, distillation products, mixtures of such distillation products, mixtures of hydrocarbons and distillation products, No. 1 or No. 2 diesel fuels, jet engine fuels, such as Jet-A fuel, or the foregoing fuels mixed with additives which are well-known in the prior art. Hydrocarbon fuels refer to the liquid fuels which are conventionally used in reaction motors, including, but not limited to, industrial gas turbines, engines used in jet propelled aircraft or any other gas turbine engine, all of which are conventionally known in the art and, for example, certain of the aviation and other gas turbine fuels discussed in volume 3, third edition, ENCYCLOPEDIA OF CHEMICAL
TECHNOLOGY, pages 328 - 351 (1979). Various hydrocarbon fuels which are particularly desirable or jet aircraft engines, are also described at column 6, lines 30 - 74 of U.S. Patent No.
2,782,592 and at column 2, lines 28 to column 3, line 23 o~
U.S. Patent No. 2,959,315 both of which are incorporated by reference herein in their entirety.
Although all of the foregoing hydrocarbon fluids can be used in the present invention, and the advantages of the present invention apply thereto, it is an unexpected advantage of the present invention that pure, untreated, low-cost hydrocarbon fluids can be used as fuel in jet engines without ~pecial handling, without further treatment, without costly quality control procedures, and without the need for special processing either prior to or subsequent to loading the fuel in the aircraft. Furthermore, these same advantages apply to all other processes and systems which utilize hydrocarbon fluids including, but not limited to, the petrochemical and plastics industries, the synthetic fuels industry, commercial and home heating industries and the like.
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Dkt. No. 13-DV-10367 16 ! ~
The fluid containment article of the present ~ -invention may be any component which is adapted to contain hot :
hydrocarbon fluid~ for example, liquid hydrocarbon jet engine or diesel fuel heated at a temperature at which decomposition products form in hydrocarbons, hydrocarbons circulating in conduits, heat exchangers and the like o~ refineries, polymer plants and power plants, furnaces and the like. Such articles for containing hot hydrocarbon fluid are defined herein as fluid containment articles. Examples of uch fluid containment articles are discussed above and include any device in which hot hydrocarbon fluid can be confined, stored, transported or otherwise subjected to heat exchange without ignition or combustion of the hot fluid. The present invention is particularly adaptable to heat transfer surfaces where heat is transferred from a combustor or other heat source through a wall to liquid hydrocarbon fluid. Specific examples of fluid containment articles for hot hydrocarbon fluids in accordance with the present invention include fuel storage tanks, conduits for transporting liquid fuel, coils and other devices for heat exchange contact with fuel, fuel injector surfaces and the like.
one such fluid containment article is shown in ~-: Figure 1 which represents a heat exchanger for cooIing the ~: 25~ high pressure turbine no~le of a jet engine by transferring the heat gen~rated therein to liquid hydrocarbon fuel confined in and tra~sported through conduits or chambers adjacent the nozzle wall.
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In Figure 1, liquid hydrocarbon fuel enters the high pressure turbine nozzle at condui~ 6 and passes through heat exchanger 2 where h~at from combustion chamber 16, for example, operating at a temperature such that the walls of the nozzle which form chamber 1~ ha~e a temperature of about , . ~ .
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Dkt. No. 13-DV-10367 1200F, is cooled by the liquid hydrocarbon fuel passing through fuel passageway 2. Thus, ther~ is heat exchange between the walls of chamber 16 and the liquid hydrocarbon fuel passing through passageway 2. Liquid hydrocarbon fuel also passes through passageway 4 where heat exchange also occurs between the wall of the chamber 16 and the liquid hydrocarbon fuel in passageway 4. Vaporized hydrocarbon gas 12 flows into chamber 16 through gas injection ports 10.
Referring to Figure 2 which shows in more dPtail the fuel containment passageway of Figure 1, Figure 2 being taken along the lines II - of Figure 1, liquid hydrocarbon fuel passageway 2 contains walls 24 and 26 through which fuel passageway 22 is ~ormed. Special barrier materials, identified herein a5 fuel diffusion barrier material 20 is coated on substrates 24 and 26 so that it forms a liner or liner material in passageway 22. Thus, numeral 20 in Figure 2 represents the fuel diffusion barrier material or liner material of the present invention.
Substrates 24 and 26 of Figure 2, which represent the heat exchanger walls of chamber 16 in the high pressure turbine no~zle of Figure 1, are generally constructed of any conventional material as well known in the art. For example, such substrates may ~e stainless steel, corrosion-resistant alloys of nickel and chromium commercially available as INCONEL~, a trademark of the International Nickel Company~
Inc., a high-strength, nickel-base, corrosion-resistant alloy identified as H~STELLOY~, a trademark of Union Carbide Corporation, and the like. It is these typical substrate materials which appear to cause or promote the formation of fuel thermal decomposition products, such as gum, various polymers, coke, sulfur compounds, other decomposition 2~S~2~
Dkt. No. 13-DV-10367 impurities or mixtures thereof, in liquid hydrocarbon fluids and fuels. It is the surface of substrates 26 and 24 which are adapted for contact with the hydrocarbon fuel by the formation of passageways, for example as shown by numeral 22 in Figure 2, therein. Liquid hydrocarbon fuel can be transported through passageway 22 by any appropriate means (not shown), and the hydrocarbon fuel as it passes through passageway 22 contacts the substrate. However, in accordance with the present invention, passageway 22 is actually formed from liner material 20 which has been coated upon the surfaces of substrates 24 and 26 which form passageway 22.
Accordingly, as the liquid hydrocaxbon passes thxough passageway 22, it actually contacts liner material 20. For best results, liner material 20 is continuous and completely covers all surfaces of passageway 22 which are formed from substrates 24 and 26 and which provide a heat exchanye relationship because of its conta~t with the liquid hydrocarbon fuel.
In accordance with the present invention, liner material 20 which actually forms pas;ageway 22 by virtue of the continuou~ coating of liner mate;rial 20 to the passageway formed by substrates 24 and 26, is a diffusion barrier material which is catalytically-inactive and inhibits or prevents formation o~ fuel thermal decomposition products, for example, amorphous tantalum oxide, or it is a diffusion barrier material which is catalytically-active and catalyzes the thermal decomposition in the fuel to promote the formation of a loosely-adher~nt coke in the fluid, for example, amorphous zirconium oxide. The liner is also a physical diffusion barrier to the hydrocarbon fuel and prevents contact between the fuel and the substrate. Thus, liner material 20 which coats substrates 24 and 26 and thereby ~orms passageway 2 ~
Dkt. No. 13-DV-10367 22, is an inert or catalytically-inactive diffusion barrier material which prevents, reduces or inhibits the formation of gum, cok~, sulfur compounds, and/or other decomposition impurities and the like and thereby prevents, reduces or inhibits the deposit of gum, coke, sulfur compounds and/or other decomposition impurities on the surfaces of the passageway, or a catalytically-active difusion barrier material which catalyzes thermal decomposition in the fuel to promote the formation of a loosely-adherent or substantially non-adheren~ coke while simultaneously inhibiting the formation of gum, sulfur compounds and/or o~her decomposition impurities and the like and thereby prevents, reduces or inhibits the deposit of gum, coke, sulfur compounds and/or other decomposition impurities on the surfaces o~ the passageway, the coke remaining suspended or dispersed in the fuel wherein it is transported with the fuel to the combustor for burning.
In accordance with the present invention, preferred liner or diffusion barrier materials which may be applied to the surfaces of the metal substrates in contact with the fuel in fuel containment articles or in a fuel containment system, and which causes catalytic formation of coke, for example coke which loosely adheres to the liner material and remains dispersed in the fuel, or which prevent or inhibit the formation of all thermal decomposition products in the fuel, include metal oxides, and more preferably, amorphous metal oxides.
As explained above, the liner or liner material of the present invention can b~ a metal oxide which is itself inert to chemical reaction, that i~, catalytically-inactivs, with the hydrocarbon and its impurities. In certain 2 ~
Dkto No. 13-DV-10367 embodiments, the liner or lin~r material of the present invention can be a metal oxide which is itself a catalyst which accelerates hydrocarbon and impurities reaction to products, such as c~ke which tends not to adhere to the liner.
The inert or catalytic liner can be deposi~ed on the substrate by chemical vapor deposition. In the case of an inert amorphous metal oxide, the liner can be amorphous tantalum oxide (Ta2O5~. In the case of the catalytic amorphous metal oxide, the liner can be amorphous zirconium oxide (ZrO2).
Although the thickness of the liner material, that is, the metal oxide film is not critical, the metal oxide film can be quite thin, on the order of about one-half micron in order to prevent micro-cracking due to surface stresses which could degrade the di~fusion-barrier nature of the liner. In certain preferred embodiments, the metal oxide is amorphous so as to be homogeneous and closely packed in order to prevent diffusion and contact between the fluid and substrate.
Non-amorphous or crystalline metal oxides can also be deposited on substrates in accordance with the present invention as long as such deposits or coatings form a continuous, closely packed coating to prevent diffusion and contact between the ~luid and substrate.
~he metal oxides which may be coated on the surface of the metal substrate to produce a diffusion barrier to hydrocarbon fuel, and thereby prevent or inhibit ~uel thermal decomposition products, such as gums and other polymers, sulfur compounds and/or other decomposition impurities, and in certain embodiments, coke, may be any of the known methods ~or depositing metal oxide coatings on surfaces o~ metals. The liner can be attached to the substrate, for example, by the 2 ~ 6 2 0 2 ~
Dkt. No. 13-DV-10367 chemical vapor deposition (CVD) process, and more specifically, by the chemical vapor infiltration (CVI) process. The liner can also be attached by plasma CYD or by the sol-gel precipitation process. The zirconium oxide, tantalum oxide and other metal oxides whic~ form the liner of the present invention may be deposited by any of the conventional techniques, such as those disclosed in volume 15, third edition of the Kirk-Othmer ENCYCLOPEDIA OF CHEMICAL
TECHNOLOGY, pages 252 - 269 entitled "~etallic Coatings (Survey)". The plasma deposition of zirconia is discussed and described in U.S. Patent No. 3,467,583 which is incorporated by reference herein in its entirety.
Although, as explained above, the present invention has utility in any fuel containment article or in any fuel containment system in which fuel does not undergo combustion, and it is particularly useful in forming a diffusion barrier in fuel containment articles and fuel containment systems wherein the fuel is used as a heat exchange medium to remove heat from various systems in gas turbines, both industrial and those used in aircraft and the like, it is particularly useful in the heat exchanger surfaces in fuel systems of a gas turbine, a scramjet engine, a ramjet engine, or a turbojet engine or as a conduit for transporting heated hydrocarbon fuel in a fuel system of any of the foregoing. Unlike the prior art processes and fluid containment articles and systems, the processes and fluid containment articles of the present invention can use conventional low-cost fluids without any disadvantage. The prior art processes and fluid containment articles must use fuels containing additives, special fuel processing procedures and/or special handling, all oP which are costly, create additional problems and generate or promote the generation of NOX. With the processes 2~02~
Dkt. No~ 13-DV-10367 and articles of the present invention, there is a substantially improved system in which NOX generation can be minimized.
Application of the benefits to be derived from the present invention are quite extensive. One application of these benefits is to provide a heat exchanger surface which can be used to gasi~y jet fuel without ~ouling of the heat exchanger surface. The gaseous fuel can then ~e injected into a gas turbine combustor in a uniform fashion rapidly mixing with air so as to burn at a uni~orm temperature. Such uniform temperature combustion would substantially reduce the formation of nitrogen oxide pollutants. Another application would also involve haating the jet fuel to a very high lS temperature so as to obtain a high heat sink for cooling various engin~ and aircraft parts ancl systems. Another application would involve coating parts such as Xuel nozzles, injectors, and flow distribution jets so as to avoid deposit buildup which would plug the nozzles, injectors and jets.
Another application would involve coating of valves so as to avoid sticking and seizing ~rom gums or cokes. These and other applications and benefits of the present invention will become obvious to those skilled in the art based on the teachings o~ the present invention.
The following specific example describes the methods and articles of this invention. It is intended for illustrative purposes only and should not be construed as limiting the present inYention.
A stainless steel planchette or coupon measuring 50mm long by 8mm wide by 2mm thick made from 304 stainless steel was coated with a 0.4 micron thick layer o~ tantalum oxide, Ta2O5, by a conventional chemical vapor deposition process~
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Dkt. No. 13-DV-10367 The test was conducted by flowing commercial grade Jet-A kerosene aviation fuel over a planchette for 8 hours at 970F and 420 psia. A total of 0.74 pounds of hot (970F) fuel was passed over the planchette during the 8-hour tPst.
No attempt was made to remove air from the fuel.
In Figure 3, planchette 30 was photographed prior to exposure to coking conditions, that is, prior to the test set forth above. On planchette 30, lower portions or section 34 was coated and remained coated with the tantalum oxid~, and upper portion or section 32 was sand blasted to remove the coating of tantalum oxide. Planchette 30 was exposed to the test conditions specified above, and after exposure to the flowing, hot Jet-A fuel, the planchette was removed and photographed and is shown as planchette 40 in Figure 30 Comparison of planchettes 30 and 40 shows that a deposit formed on uncoated (upper) portion 42 of planchette 40. Aft~r examination of coated reg:ion 44 and uncoated region 42 of planchette 40, the deposit on region 42 was removed by burning in oxygen to form carbon dioxide and sulfur dioxide.
The total amount of deposit was dete:rmined to be O.2 mg which corresponds to a deposit rate of 3.1 micrograms/hr/cm2 for the 8-hour test. ~ased on prior tests of uncoated samples, it is judged that the deposit rate is highest during initial exposure (up to 100 micrograms/hr/cm2 for ~ 0.5 hour duration test), and that the weight ratio of car~on to sulfur composition ~f the deposit is about 2 to 1.
Figure 4 shows uncoated (sand blasted) region 32 of planchette 30 before the test. Figure 5 shows the deposit formed on uncoated region 42 o~ planchette 40 after the test.
The rock-shaped crystalline deposit shown in Figure 5 was found to contain up to 30 - 40~ sulfur. As the sulfur ;. . .. : :
Dkt. No. 13-DV-10367 conc~ntration in the Jet-A fuel is only about 200 ppm, this represents a high concentration in the deposit. These same crystals were determined by x-ray diffraction to be chromium sulfide, indicating that the sulfur impurities in the fuel reacted with chromium in the 304 stainless steel. No chromium could be found in the Jet-A fuel feed, hence the chromium had to come from the steel. The black appearance of the deposit is characteristic of either carbon or chromium sulfide, leading to the spPculation that chromium sulfide could easily be misinterpreted as coke.
Figure 6 shows coated portion 34 of planchette 30 before the test. Figure 7 shows coatsd portion 44 (different area) o~ planchette after the test. There is no evidence of deposit on coated portion 44 even at 10,000 X magnification (not shown) using a scanning electron beam microscope.
Clearly the Ta2O5 prevented contact between chromium in the metal and sulfur in the fuel. No other type of deposit was observed on the coating.
Tasts similar to those above were conducted at 700F and 100 psia for 10 hours using boiling J~t-A fuel. For this test, air was bubbled into the l.iquid fuel to increase oxygen concentration. The results wer~ identical to those shown in Figure 3 insofar as depo~it~ formed on the uncoated portion, and no deposit formed on the Ta205 coated portionO
The foregoing clearly establishes that the use of a liner material of the present invention prevents diffusion between the substrate and the hydrocarbon with subsequent chemical reaction leading to surface deposit formations.
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Dkt. No. 13-DV-10367 Based on the foregoing results, it is further evident to one skilled in the art that similar diffusion barrier results can be obtained with other metal oxides on other substrate materials using various coating deposition processes.
While other modifications of the invention and variations thereof which may be employed within the scope of the invention, have not been described, the invention is intended to include such modifications as may be embraced wi~hin the following claims.
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-1- Dkt. No. 13-DV-10357 FLUID CONTAINMENT ~RTICLE FOR HOT HYDROCARBON
FLUID ~ND METHOD OF PREVENTING FUEL
THERMAL DECOMPOSITION DEPOSITS
Inventor: George A. Coffinberry BACKGROUND OF THE INVENTION
The present invention relates generally ~o deposits formed on surfaces in contact with hydrocarbon fluids, and more particula:rly, to a method o~ preventing or reducing the deposit of hydrocarbon fluid thermal decomposition products on surfaces in contact therewith and to a fluid containment article having a surface which inhibits the formation of gum, coke, sulfur compounds and/or other impurities formed by thermal decomposition of the fluid, without resorting to modification of the fluid, without adoption of special procedures and without installation of special equipment for ehelr use.
Because high temperature is usually associated with undesirable levels;of hydrocarbon fluid dep~sit for~ati~n, the ~15 technical subject herein is~customarily referred to as thermal : instability, or in:the:case of fuels, as fuel instability.
The mechanisms for formation of deposits ~rom thermal instability have been studied and documented. In the case of fuels, it is generally accepted that there are two distinct , . . . :
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Dkt. No. 13 DV-10367 mechanisms occurring at two levels of temperature. In the first mechanism, referred to as the coking process, as temperature increases from room temperature, there is generally a consistent increase in the rate of formation of coke deposits up to about 1200F where high levels of hydrocarbon pyrolysis lead to coke formation and eventually limit the usefulness of the fuel. A second lower temperature mechanism generally peaks at about 700F and involves the formation of gum deposits. This second mechanism is generally better understood than the coking process. It involYes oxidation reactions which lead to polymerization which includes the formation of gums. Both coke and gum formation and deposits can occur simultaneously in the mid-temperature region.
Co)ce formation in hydrocarbons is discussed in U.S.
Patent No. 2,698,512, and heat stab:ility of jet fuel and the consequences of thermal degradation of the fuel are discussed in U.S. Patent No. 2,959,915, both patents being incorporated herein by reference in their entire1:y. These patents suggest specific formulations which place limitations on the fuel chemistry and impurities associated with hydrocarbon fuels so that the fuels will be usable at high temperatures without the typical formation of gums and coke.
Gum and coke formation are discussed in U~S. Pat~nt No. 3,173/247, which is incorporated by referance herein in its entirety. It is indicated therein that t very high flight speeds, heat must be transferred, particularly from the engine, to some part of the flight vehicle or to its load, and although the fuel which is stored on the vehicle, could serve to receive this heat, in practice, such procedure is unfeasible because jet ~uels are not stable to the high 2 ~
Dkt. No. 13-DV-10367 temperatures which are developed at multi-Mach speeds, instead, they decompose to produce intolerable amounts of insoluble gum or other deposits, for example coke. As with the previously referenced patents, the solution to the problem has been directed toward limitations on fuel ch~mistry and impurities associated with the fuel.
Even with the most elaborate special treatment of the fuel, coke ~ormation cannot be entirely eliminated even when a pure hydrocarbon is used because if the temperature is high enough and the time is long enough, coke formation will occur. On the other hand, the chemistry of the hydrocarbon fluid mixture and the chemistry of the containment vessel can have a major influence on deposit mechanisms and deposit rates at the temperatures where it is most desirable to use the ~luid. In the lower temperature region where gum formation occurs, oxygen from air dissolved in the liquid is the major adverse ingredient. Boiling amplifiles this adversity because of the oxygen concentration effect of gas bubbles adjacent to hot walls. If oxygen or air is absent, gum formati~n is not likely to occur.
In much of the prior art, the problems associated with gum and coke thermal deposits has predominatPly dealt with bulk fluid chemistry and reactions which can take place within the fluid. These investigations have involved a wide range of hydrocarbon compositions and the presence of numerous impurities such as sulfur compounds, nitrogen compounds, oxygen and trace metals. It has been obserYed that deposits attached to containment walls often contain very large quantities of sulfur and nitro~en compounds or intermediates thereof in addition to gums and cokes. Little attention has, however, been given in the prior art to the role o~ the 2~2~2~
Dkt. No. 13-DV-10367 ~4-chemistry and reactions which directly take place between the containment walls and the fluid.
-Even though wall reactions are not well understood, it can be generally supposed thak fluid-wall deposit thickness reactions might be reduced if the wall were coated with some form of relatively inert material; for example, porcelain or glass coatings are often used to generally prev~nt deposit on such common items as stoves and water tanks. These coatings are, however, not structurally suitable for the application envisioned by the present invention. Other inert non-sticking coatings include such polymers as Teflon, but these materials are not suitable at the high temperatures under consideration.
In U.S. Patent No. 3,157,990, certain phosphate additives are added to the monopropellant wherein the phosphates decompose in the reaction chamber and form a coating, probably a phosphate coating, on the internal generator surfaces, and it is suggested that this coating effectively inhibits carbon decomposition and scaling. In U.S. Patent No. 3,236,046, which is incorporated by reference herein in its entirety, the i~terior surfaces of stainless steel gas generators are passivated ~with sulfurous materials to overcome deposition of coke o~ the ~urfaces of the gas generator, and passi~ation is defined as a pretreatment which sub~tantially reduces initial cataly-tic coke ~o~mation. From these pàt~nts, it is deduced that the coke inhibiting mechanisms is in fact a passivation process in which the phosphate or ~ulfur reacts with ~he wall in much the same way as oxygen reacts with iron or copper to form oxides which protect the wall from further reaction. Ordinarily red oxide paint primer is a similarly well-known approach. The patents are suggestive that some ~orm o~ r~action takes ~lace between the fuel and the wall.
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Dkt. No. 13~DV-10367 In U.S. Patent No. 4,078,604, which is incorporated by reference herein in its entirety, heat exchangers are characterized by thin-walled corrosion resistant layers of electro-deposited gold or similar corrosion-resistant metals on the walls of the cooling channels within the inner wall, and the cooling ohannels are covered with the electro-deposited layer of gold in order to make the surfaces corrosion resistant to such storable liquid fuels as red fuming nitric acid. In this prior art case, the wall is protected from corrosion by the propellent, but the intent is not to prevent deposit formations. It is also known from prior art that gold plating has been used to prevent surface catalytic reactions with fuel in which case the objective is not to interfere with gum formation for the purpose of evaluatin~ fuel chemical stability.
Thermal instability and fuel instability, referred to above, are becoming more significant with developing technology, and it will become ~ven more significant as processes and machinery will be required to operate at higher temperatures as afforded by advances in materials technology and as the chemical quality of hydrocarbons for fuels, oils, lubricants, petrochemical processes (plastics and synthetics) and the like, decreases. Furthermore, hydrocarbon fluids, ~5 fuels and oils deri~ed ~rom non-petroleum sources, such as shale and coal, will have significantly more problems with thermal instability because of their high content of olefins, sulfur and other compounds. Accordingly, it i5 advantageous to provide fluid containment articles and processes for preventing the ~ormation of adverse decomposition products and foulants in such applications where thermal instability, including fuel ins~ability, is a problem as a result of exposure to such fluids to high temperatures.
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Dkt. No. 13-DV-10367 In view of the foregoing, it can be seen that it would be desirable to provide fuel containment articles for containing hot hydrocarbon fluid in which decomposition products formed by thermal decomposition of the hydrocarbon fluid is avoided, eliminated or reducedO It would also be desirable to provide a method of protecting metal surfaces which contact hot hydrocarbon fluid, from the deposit of decomposition products of the hydrocarbon fluid. It can also be seen from the foregoing that it is desirable to provide methods and articles for use with hydrocarbon fuels wherein the hydrocarbon fuel can be used as a heat sink without the undesirable deposit of insoluble gums, coke, sulfur compounds or mixtures thereof on containment surfaces. It is also desirable to provide methods and articles for containment of vaporized fuel to reduce NOX emission and to provide methods and articles for containment of low quality fuels derived from coal, shale and low grade crude oil.
The disadvantages of the prior art processes and techniques discussed above involve the need to alter the hydrocarbon chemistry, maintain strict control of impurities and/or provide additives and special processing such as passivation treatments. All of these techniques constrain the use of the fluid, increase cost and promote uncertainty as to the ~uality level of the ~uel or treatment at a particular time. The present invention overcomes all of these limitation~ by providing a method and articles which eliminate or reduce the surface reactions which lead to formation of thermal instability deposits from hydrocarbon fluids and which eliminate or reduce adherence o~ deposits on sur~aces using ordinary low-cost fuels, oils and other hydrocarbons without :~
focusing special attention to impurities or quality.
Furthermore, there are a multitude of processes, systems and . ~ : ,, . . . , --. . .: . ~ .
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Dkt. No. 13-DV-10367 devices including petrochemical processes, machine tools, automobile engines, aircraft gas turbine engines, and marine and industrial engines in which surface deposits from hydrocarbon fluids, fuels and oils are a major problem.
Deposits can foul heat exchangers, plug fuel injectors and lubrication distribution jets, jam control valve and cause problems with many other types of operating and control devices associated with hydrocarbon fluids, fuels and oils.
It is a primary objective of this invention to overcome these disadvantages.
SUMMARY OF THE INVENTION
These and other disadvantages are overcome in lS accordance with the present invention by providing a coating, hereinafter referred to as a liner, liner material, diffusion barrier or diffusion barriex material on ~ fluid containment metal surface, also referred to here:in as a substrate.
In accordance with the present invention, there is provided a method and articles for preventing the deposit of decomposition products and/or therma:L instability deposits from hot hydrocarbon fluids on a metal substrate, and metal surfaces are protected from the deposit of hydrocarbon fluid decomposition products resulting from thermal decomposition of hot hydrocarbon fluid in a fluid containment article or system carrying hot hydrocarbon fluid. Thus, for example, as a result of the present invention, heat generated by combustion of fu~l in the operation of a combustor which utilizes hydrocarbon fuel, or heat from other sources, can be transferred by heat exchange principles to hydrocarbon fuel without the undesirabl~ thermal decomposition of the fuel and the subseguent deposit of thermal decomposition products on the walls of the articles containing the fuel.
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Dkt. No. 13-DV-10367 In one aspect of the present invention, there is provided a fluid containment article for containing hot hydrocarbon fluid comprising a substrate having a surface adapted for contact with the hydrocarbon fluid wherein the surface comprises a liner selected from the group consisting of a catalytically-active diffusion barrier material which catalyzes thermal decomposition in the hydrocar~on fluid to promote the formation of coke, the coke being subs-tantially non-adherent to the liner, and a ca~alytically-inactive diffusion barrier mat~rial which is inert to thermal decomposition in th~ hydrocarbon fluid and inhibits the formation of coke, the catalytically-active and catalytically-inactive diffusion barrier materials inhibiting the *ormation of gum, sulfur compounds or other decomposition impurities or mixtures thereof formed by thermal decomposition of the hydrocarbon ~luid, the liner material being a physical diffusion barrier located between the substrate and hydrocarbon fluido In another aspect of the present invention, there is provided a method of preventing the deposit of thermal decomposition products in a hydrocarbon fluid on a metal surface of a device adapted to contain the hydrocarbon fluid I ~:
comprising applying to the metal surface a layer o~ diffusion ~, barrier material which is inert to chemical formation o~
thermal decomposition products in the fuel. In this embodiment of the invention, the liner or liner material itself is inert to chemical reaction with hydrocarbons and hydrocarbon impurities, that is, it is inert to the chemical 3Q formation of such thermal dPcomposition products as gum, co~e, '! ~ ' sulfur compounds and other decomposition impurities in the ~:
fluid. As used herein, the liner in this instance is a catalytically-inactive difusion barrier material.
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Dkt. No. 13-DV-10367 _g_ In still another aspect of the present invention, the deposit of thermal decomposition products in a hydrocarbon fluid on a metal surface of a device adapted to contain the hydrocarbon fluid is prevented by applying to the metal surface a layer of diffusion barrier material which catalyzes thermal decomposition in the hydrocarbon fluid to promote the formation o~ coke, the diffusion barrier being a deterrent to the formation of gum and sulfur compounds. Thus, in this embodiment, the formation of coke, which is substantially non-adheren~ or loosely-adherent to the diffusion barrier material, is promoted while the formation of gum, sulfur compounds and other decomposition impurities is inhibited. In this embodiment of the invention the liner or liner material itself is a catalyst which accelerates or promotes the reaction of hydrocarbon and hydrocarbon impurity to beneficial products (coke) which do not adhere or tend not to adhere to the liner or liner material. The coke and any similar non-polymer products can be tolerated in fuel because they do not tend to adhere to surfaces, and they burn in the combustor along with the fuel. As used herein, the liner in this embodiment is a catalytically-active diffusion barrier material.
The coating material or liner material is deposited on a surface which is adapted for contact with a hydrocarbon fluid, for example a distillate fuel, and depending on khe particular material, it inhibits or prevents the formation of gum, coke, sulfur compounds, or other decomposition impurities or mixtures thereof formed by the thermal decomposition of the hydrocarbon fluid, or it catalyzes the formation of coke while inhibiting or preventing the formation o gum, sulfur compounds and other decomposition impurities. The coating or liner material is al~o a physical diffusion barrier to the hot 2~2~2~
Dkto No. 13-DV-10367 hydrocarbon fluid, that is, it will ~ot permit the diffusion of or pa~sing of the fluid through the material to the substrate on which the coating material is deposited. Thus, the liner material is a physical barrier located b~tween the substrate and the hydrocarbon fluid.
From the foregoing, it is evident that the present invention solves the problems related to the formation of gum, coke, sulfur and other deposit-forming reactions which are chemically associated with contact between hot hydrocarbon fluid and the materials which the fluid contacts, for ex~mple a wall. The present invention also solves the problems associated with the attachment or adherence of deposits to materials which the fluid contacts, by either physical or chemical means. In certain embodiments, the present invention also preferentially directs fluid-surface reactions toward deposits which tend not to adhere to materials which the fluid contacts.
Although there is no intention to be bound by any particular theory or explanation of t:he mechanism(s) by which the present invention inhibits the formation of gum, coke, ~-sul~ur compounds and other deposit-forming species which are ~ormed by thermal decomposition of hydrocarbon fluid, it is believed that chPmical reactlons ta~e place between specific atoms and compounds which are part of the substrate chemistry and react under the in~luence of temperature with hydrocarbons and hydrocarbon impuritles such as nitrogen, oxygen and sulfur and their compounds, to form metal nitrogen, metal oxygen and metal sulfur compounds. These metal compounds form deposits and/or precursors to deposits and provide an a tachment mechanism between the substrate and other deposits. This theory is supported by the argument that chemical-absorption 2 ~ 2 ~
Dkt. No. 13-DV-1036/
provides a much stronger surface bond than would simple physical absorption to the surface. In the specific case of -gum deposits, it is theorized that metal atoms and metal compounds in the substrate can react to form hydrocarbon radicals which are then highly susceptible to further reaction such as with oxygen, to lead ultimately to polymerization and gums. Substrate reactions can also provide chemistry which is known in the art to be precursors to gums, and after the precursors attach to the substrate, they become the means for which gums and cokes and other deposits can grow by means of chemic~l or physical means, to consequential proportions.
In accordance with the present invention, a liner material on the surface shields objectionable metal atoms and metal compounds in the substrate or wall from reaction with khe hydrocarbon fluid and its impurities. The same liner material also physically prevents or :inhibits diffusion of metal atoms and metal compounds into the hydrocarbon fluid.
The same liner material also prevents or inhibits diffusion of the ~ydrocarbon fluid and any impurities that it contains, to the substrate.
Two types of liner or liner materials may be used in the processes and fluid containment materials of the present invention. A first type of liner material is catalytically-inactive diffusion barrier material. A
catalytically-inactive diffusion barrier material is one which is inert to the formation of any decomposition products in hot hydrocarbon fluid which contacts it. Thus, when such a catalytically-inactive diffusion barrier material is used as the liner on a hydrocarbon fluid containment article adapted to contact hydrocarbon fluid, there is substantially no thermal decomposition of the hydrocarbon fluid at elevated ~2~4 Dkt. No. 13-DV-10367 --1~
temperatures, for example, up to 900F, and there is no gum, sulfur compound, coke or other decomposition impurity formation in the heated fluid.
A second type of liner material is catalytically-active diffusion barrier material. A
catalytically-active diffusion barrier material is one which actively permits or promotes the formation in hot hydrocarbon fluids of a compound or compounds which have no adverse effect on the utilization of the fuel, on the flow and transport of the fuel and/or on the components contacted by the fuel. More specifically, a catalytically-active diffusion barrier material is one which actively permits or promotes the formation of coke in the hot hydrocarbon fluid, a coke which remains substantially dispersed in the fluid as it flows and is transported through containment articles and other components and is ultimately burned, or otherwise utilized, with the fluid. Coke which is so formed and remains substantially dispersed in the fluid in which it is formed, is defined herein as loosely-adhered or substantially non-adherent coke because it tends not to stick to or adhere to containment walls and elements either by physical or chemical attraction. With the formation of coke in the presence of the catalytically-active diffusion barrier material is the simultaneous inhibition or repression of formation of gumj sulfur compounds and/or other decomposition impurities in the hydrocarbon fluid. In both types o~ liner material, the diffusion barrier material is also a physical barrier or obstacle located between:the substrat~ and the hydrocarbon fluid and prevents physical contact of the fluid and the substrate.
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Dkt. No. 13-DV-10367 13~
As used herein, the phrase 'iother decomposition impuritiesl' refers to any compounds which can form as a result of the thermal instability of a hydrocarbon fluid, other than gum, sulfur compounds and coke. The prior art and literature disclose many such species and can include, for example, metal-nitrogen compounds, metal-oxygen compounds, various olefins and/or pol~mers formed therefrom, saturated and unsaturated polymers, cyclic and aromatic hydrocarbon compounds and the like. The other decomposition impurities which can form in a hot hydrocarbon fuel are frequently dependent on the initial fuel content including the starting impurities therein.
BRIEF DESCRIPTION OF THE DRAUINGS
These and various other features and advantages of the invention can be best understood from the following description taken in conjunction with the accompanying drawings in which:
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Figure 1 is a partial longitudinal view of a high pressure turbine nozzle for a jet engine fueled by distillate fuel and incorporating the heat exchanger wall construction of the present invention~
Figure 2 is a sectional view taken along the line of II - II of Figure 1 showing fual conkainment passages for circulating distillate fuel.
Fi~ure 3 is a photograph of two (2) stainless steel planchettes showing before and after exposures to hot jet-A
fuel.
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- , ~ - ': ' ' ' ' 2 ~ 2 4 Dkt. No. 13-DV-10367 Figure 4 is a scanning electxon beam micrograph (magnified 2000X) of an uncoated area (prior to testing) of a planchetke which has been sand blasted~
Figure 5 is a scanning electron beam micrograph (magnified 5000X) of an uncoated area (after testing) of a planchette.
Figure 6 is a scanning electron beam micrograph ~;
(magnified 2000X) of a coated area (prior to testing~ of a planchette.
Figure 7 is a scanning electron beam micrograph (magnified 2000X) of a coated area (after testing) of a lS planchette.
DETAILED DESCRIPTION OF THE INVENTION
The terms hydrocarbon fluid, hydrocarbon fuel and distillate fuel ~ay be used interchangeably herein.
The invention has applicab:ility to any hydrocarbon fluid in which gum or other polymers, coke, sulfur compounds or any other decomposition impurities form when the fluid is exposed to heat. Although the invention i~ not directed to or limited by any particular hydrocarbon fluid or hydrocarbon fuel, typical ~uels for which the method and fluid containment articles of the present invention are adapted, and typical fu21s from which the substrates of fluid containment articles are protected in accordance with the present invention, are the hydrocarbon or distillate fuels generally discussed above and include hydrocarbons and distillation products thereof which are generally liquid at room temperature. The fluids '' -.
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Dkt. No. 13-DV-10367 may be pure hydrocarbon or mixtures of hydrocarbons, distillation products, mixtures of such distillation products, mixtures of hydrocarbons and distillation products, No. 1 or No. 2 diesel fuels, jet engine fuels, such as Jet-A fuel, or the foregoing fuels mixed with additives which are well-known in the prior art. Hydrocarbon fuels refer to the liquid fuels which are conventionally used in reaction motors, including, but not limited to, industrial gas turbines, engines used in jet propelled aircraft or any other gas turbine engine, all of which are conventionally known in the art and, for example, certain of the aviation and other gas turbine fuels discussed in volume 3, third edition, ENCYCLOPEDIA OF CHEMICAL
TECHNOLOGY, pages 328 - 351 (1979). Various hydrocarbon fuels which are particularly desirable or jet aircraft engines, are also described at column 6, lines 30 - 74 of U.S. Patent No.
2,782,592 and at column 2, lines 28 to column 3, line 23 o~
U.S. Patent No. 2,959,315 both of which are incorporated by reference herein in their entirety.
Although all of the foregoing hydrocarbon fluids can be used in the present invention, and the advantages of the present invention apply thereto, it is an unexpected advantage of the present invention that pure, untreated, low-cost hydrocarbon fluids can be used as fuel in jet engines without ~pecial handling, without further treatment, without costly quality control procedures, and without the need for special processing either prior to or subsequent to loading the fuel in the aircraft. Furthermore, these same advantages apply to all other processes and systems which utilize hydrocarbon fluids including, but not limited to, the petrochemical and plastics industries, the synthetic fuels industry, commercial and home heating industries and the like.
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Dkt. No. 13-DV-10367 16 ! ~
The fluid containment article of the present ~ -invention may be any component which is adapted to contain hot :
hydrocarbon fluid~ for example, liquid hydrocarbon jet engine or diesel fuel heated at a temperature at which decomposition products form in hydrocarbons, hydrocarbons circulating in conduits, heat exchangers and the like o~ refineries, polymer plants and power plants, furnaces and the like. Such articles for containing hot hydrocarbon fluid are defined herein as fluid containment articles. Examples of uch fluid containment articles are discussed above and include any device in which hot hydrocarbon fluid can be confined, stored, transported or otherwise subjected to heat exchange without ignition or combustion of the hot fluid. The present invention is particularly adaptable to heat transfer surfaces where heat is transferred from a combustor or other heat source through a wall to liquid hydrocarbon fluid. Specific examples of fluid containment articles for hot hydrocarbon fluids in accordance with the present invention include fuel storage tanks, conduits for transporting liquid fuel, coils and other devices for heat exchange contact with fuel, fuel injector surfaces and the like.
one such fluid containment article is shown in ~-: Figure 1 which represents a heat exchanger for cooIing the ~: 25~ high pressure turbine no~le of a jet engine by transferring the heat gen~rated therein to liquid hydrocarbon fuel confined in and tra~sported through conduits or chambers adjacent the nozzle wall.
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In Figure 1, liquid hydrocarbon fuel enters the high pressure turbine nozzle at condui~ 6 and passes through heat exchanger 2 where h~at from combustion chamber 16, for example, operating at a temperature such that the walls of the nozzle which form chamber 1~ ha~e a temperature of about , . ~ .
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Dkt. No. 13-DV-10367 1200F, is cooled by the liquid hydrocarbon fuel passing through fuel passageway 2. Thus, ther~ is heat exchange between the walls of chamber 16 and the liquid hydrocarbon fuel passing through passageway 2. Liquid hydrocarbon fuel also passes through passageway 4 where heat exchange also occurs between the wall of the chamber 16 and the liquid hydrocarbon fuel in passageway 4. Vaporized hydrocarbon gas 12 flows into chamber 16 through gas injection ports 10.
Referring to Figure 2 which shows in more dPtail the fuel containment passageway of Figure 1, Figure 2 being taken along the lines II - of Figure 1, liquid hydrocarbon fuel passageway 2 contains walls 24 and 26 through which fuel passageway 22 is ~ormed. Special barrier materials, identified herein a5 fuel diffusion barrier material 20 is coated on substrates 24 and 26 so that it forms a liner or liner material in passageway 22. Thus, numeral 20 in Figure 2 represents the fuel diffusion barrier material or liner material of the present invention.
Substrates 24 and 26 of Figure 2, which represent the heat exchanger walls of chamber 16 in the high pressure turbine no~zle of Figure 1, are generally constructed of any conventional material as well known in the art. For example, such substrates may ~e stainless steel, corrosion-resistant alloys of nickel and chromium commercially available as INCONEL~, a trademark of the International Nickel Company~
Inc., a high-strength, nickel-base, corrosion-resistant alloy identified as H~STELLOY~, a trademark of Union Carbide Corporation, and the like. It is these typical substrate materials which appear to cause or promote the formation of fuel thermal decomposition products, such as gum, various polymers, coke, sulfur compounds, other decomposition 2~S~2~
Dkt. No. 13-DV-10367 impurities or mixtures thereof, in liquid hydrocarbon fluids and fuels. It is the surface of substrates 26 and 24 which are adapted for contact with the hydrocarbon fuel by the formation of passageways, for example as shown by numeral 22 in Figure 2, therein. Liquid hydrocarbon fuel can be transported through passageway 22 by any appropriate means (not shown), and the hydrocarbon fuel as it passes through passageway 22 contacts the substrate. However, in accordance with the present invention, passageway 22 is actually formed from liner material 20 which has been coated upon the surfaces of substrates 24 and 26 which form passageway 22.
Accordingly, as the liquid hydrocaxbon passes thxough passageway 22, it actually contacts liner material 20. For best results, liner material 20 is continuous and completely covers all surfaces of passageway 22 which are formed from substrates 24 and 26 and which provide a heat exchanye relationship because of its conta~t with the liquid hydrocarbon fuel.
In accordance with the present invention, liner material 20 which actually forms pas;ageway 22 by virtue of the continuou~ coating of liner mate;rial 20 to the passageway formed by substrates 24 and 26, is a diffusion barrier material which is catalytically-inactive and inhibits or prevents formation o~ fuel thermal decomposition products, for example, amorphous tantalum oxide, or it is a diffusion barrier material which is catalytically-active and catalyzes the thermal decomposition in the fuel to promote the formation of a loosely-adher~nt coke in the fluid, for example, amorphous zirconium oxide. The liner is also a physical diffusion barrier to the hydrocarbon fuel and prevents contact between the fuel and the substrate. Thus, liner material 20 which coats substrates 24 and 26 and thereby ~orms passageway 2 ~
Dkt. No. 13-DV-10367 22, is an inert or catalytically-inactive diffusion barrier material which prevents, reduces or inhibits the formation of gum, cok~, sulfur compounds, and/or other decomposition impurities and the like and thereby prevents, reduces or inhibits the deposit of gum, coke, sulfur compounds and/or other decomposition impurities on the surfaces of the passageway, or a catalytically-active difusion barrier material which catalyzes thermal decomposition in the fuel to promote the formation of a loosely-adherent or substantially non-adheren~ coke while simultaneously inhibiting the formation of gum, sulfur compounds and/or o~her decomposition impurities and the like and thereby prevents, reduces or inhibits the deposit of gum, coke, sulfur compounds and/or other decomposition impurities on the surfaces o~ the passageway, the coke remaining suspended or dispersed in the fuel wherein it is transported with the fuel to the combustor for burning.
In accordance with the present invention, preferred liner or diffusion barrier materials which may be applied to the surfaces of the metal substrates in contact with the fuel in fuel containment articles or in a fuel containment system, and which causes catalytic formation of coke, for example coke which loosely adheres to the liner material and remains dispersed in the fuel, or which prevent or inhibit the formation of all thermal decomposition products in the fuel, include metal oxides, and more preferably, amorphous metal oxides.
As explained above, the liner or liner material of the present invention can b~ a metal oxide which is itself inert to chemical reaction, that i~, catalytically-inactivs, with the hydrocarbon and its impurities. In certain 2 ~
Dkto No. 13-DV-10367 embodiments, the liner or lin~r material of the present invention can be a metal oxide which is itself a catalyst which accelerates hydrocarbon and impurities reaction to products, such as c~ke which tends not to adhere to the liner.
The inert or catalytic liner can be deposi~ed on the substrate by chemical vapor deposition. In the case of an inert amorphous metal oxide, the liner can be amorphous tantalum oxide (Ta2O5~. In the case of the catalytic amorphous metal oxide, the liner can be amorphous zirconium oxide (ZrO2).
Although the thickness of the liner material, that is, the metal oxide film is not critical, the metal oxide film can be quite thin, on the order of about one-half micron in order to prevent micro-cracking due to surface stresses which could degrade the di~fusion-barrier nature of the liner. In certain preferred embodiments, the metal oxide is amorphous so as to be homogeneous and closely packed in order to prevent diffusion and contact between the fluid and substrate.
Non-amorphous or crystalline metal oxides can also be deposited on substrates in accordance with the present invention as long as such deposits or coatings form a continuous, closely packed coating to prevent diffusion and contact between the ~luid and substrate.
~he metal oxides which may be coated on the surface of the metal substrate to produce a diffusion barrier to hydrocarbon fuel, and thereby prevent or inhibit ~uel thermal decomposition products, such as gums and other polymers, sulfur compounds and/or other decomposition impurities, and in certain embodiments, coke, may be any of the known methods ~or depositing metal oxide coatings on surfaces o~ metals. The liner can be attached to the substrate, for example, by the 2 ~ 6 2 0 2 ~
Dkt. No. 13-DV-10367 chemical vapor deposition (CVD) process, and more specifically, by the chemical vapor infiltration (CVI) process. The liner can also be attached by plasma CYD or by the sol-gel precipitation process. The zirconium oxide, tantalum oxide and other metal oxides whic~ form the liner of the present invention may be deposited by any of the conventional techniques, such as those disclosed in volume 15, third edition of the Kirk-Othmer ENCYCLOPEDIA OF CHEMICAL
TECHNOLOGY, pages 252 - 269 entitled "~etallic Coatings (Survey)". The plasma deposition of zirconia is discussed and described in U.S. Patent No. 3,467,583 which is incorporated by reference herein in its entirety.
Although, as explained above, the present invention has utility in any fuel containment article or in any fuel containment system in which fuel does not undergo combustion, and it is particularly useful in forming a diffusion barrier in fuel containment articles and fuel containment systems wherein the fuel is used as a heat exchange medium to remove heat from various systems in gas turbines, both industrial and those used in aircraft and the like, it is particularly useful in the heat exchanger surfaces in fuel systems of a gas turbine, a scramjet engine, a ramjet engine, or a turbojet engine or as a conduit for transporting heated hydrocarbon fuel in a fuel system of any of the foregoing. Unlike the prior art processes and fluid containment articles and systems, the processes and fluid containment articles of the present invention can use conventional low-cost fluids without any disadvantage. The prior art processes and fluid containment articles must use fuels containing additives, special fuel processing procedures and/or special handling, all oP which are costly, create additional problems and generate or promote the generation of NOX. With the processes 2~02~
Dkt. No~ 13-DV-10367 and articles of the present invention, there is a substantially improved system in which NOX generation can be minimized.
Application of the benefits to be derived from the present invention are quite extensive. One application of these benefits is to provide a heat exchanger surface which can be used to gasi~y jet fuel without ~ouling of the heat exchanger surface. The gaseous fuel can then ~e injected into a gas turbine combustor in a uniform fashion rapidly mixing with air so as to burn at a uni~orm temperature. Such uniform temperature combustion would substantially reduce the formation of nitrogen oxide pollutants. Another application would also involve haating the jet fuel to a very high lS temperature so as to obtain a high heat sink for cooling various engin~ and aircraft parts ancl systems. Another application would involve coating parts such as Xuel nozzles, injectors, and flow distribution jets so as to avoid deposit buildup which would plug the nozzles, injectors and jets.
Another application would involve coating of valves so as to avoid sticking and seizing ~rom gums or cokes. These and other applications and benefits of the present invention will become obvious to those skilled in the art based on the teachings o~ the present invention.
The following specific example describes the methods and articles of this invention. It is intended for illustrative purposes only and should not be construed as limiting the present inYention.
A stainless steel planchette or coupon measuring 50mm long by 8mm wide by 2mm thick made from 304 stainless steel was coated with a 0.4 micron thick layer o~ tantalum oxide, Ta2O5, by a conventional chemical vapor deposition process~
2 ~ 2 ~
Dkt. No. 13-DV-10367 The test was conducted by flowing commercial grade Jet-A kerosene aviation fuel over a planchette for 8 hours at 970F and 420 psia. A total of 0.74 pounds of hot (970F) fuel was passed over the planchette during the 8-hour tPst.
No attempt was made to remove air from the fuel.
In Figure 3, planchette 30 was photographed prior to exposure to coking conditions, that is, prior to the test set forth above. On planchette 30, lower portions or section 34 was coated and remained coated with the tantalum oxid~, and upper portion or section 32 was sand blasted to remove the coating of tantalum oxide. Planchette 30 was exposed to the test conditions specified above, and after exposure to the flowing, hot Jet-A fuel, the planchette was removed and photographed and is shown as planchette 40 in Figure 30 Comparison of planchettes 30 and 40 shows that a deposit formed on uncoated (upper) portion 42 of planchette 40. Aft~r examination of coated reg:ion 44 and uncoated region 42 of planchette 40, the deposit on region 42 was removed by burning in oxygen to form carbon dioxide and sulfur dioxide.
The total amount of deposit was dete:rmined to be O.2 mg which corresponds to a deposit rate of 3.1 micrograms/hr/cm2 for the 8-hour test. ~ased on prior tests of uncoated samples, it is judged that the deposit rate is highest during initial exposure (up to 100 micrograms/hr/cm2 for ~ 0.5 hour duration test), and that the weight ratio of car~on to sulfur composition ~f the deposit is about 2 to 1.
Figure 4 shows uncoated (sand blasted) region 32 of planchette 30 before the test. Figure 5 shows the deposit formed on uncoated region 42 o~ planchette 40 after the test.
The rock-shaped crystalline deposit shown in Figure 5 was found to contain up to 30 - 40~ sulfur. As the sulfur ;. . .. : :
Dkt. No. 13-DV-10367 conc~ntration in the Jet-A fuel is only about 200 ppm, this represents a high concentration in the deposit. These same crystals were determined by x-ray diffraction to be chromium sulfide, indicating that the sulfur impurities in the fuel reacted with chromium in the 304 stainless steel. No chromium could be found in the Jet-A fuel feed, hence the chromium had to come from the steel. The black appearance of the deposit is characteristic of either carbon or chromium sulfide, leading to the spPculation that chromium sulfide could easily be misinterpreted as coke.
Figure 6 shows coated portion 34 of planchette 30 before the test. Figure 7 shows coatsd portion 44 (different area) o~ planchette after the test. There is no evidence of deposit on coated portion 44 even at 10,000 X magnification (not shown) using a scanning electron beam microscope.
Clearly the Ta2O5 prevented contact between chromium in the metal and sulfur in the fuel. No other type of deposit was observed on the coating.
Tasts similar to those above were conducted at 700F and 100 psia for 10 hours using boiling J~t-A fuel. For this test, air was bubbled into the l.iquid fuel to increase oxygen concentration. The results wer~ identical to those shown in Figure 3 insofar as depo~it~ formed on the uncoated portion, and no deposit formed on the Ta205 coated portionO
The foregoing clearly establishes that the use of a liner material of the present invention prevents diffusion between the substrate and the hydrocarbon with subsequent chemical reaction leading to surface deposit formations.
2~1~2~2~
Dkt. No. 13-DV-10367 Based on the foregoing results, it is further evident to one skilled in the art that similar diffusion barrier results can be obtained with other metal oxides on other substrate materials using various coating deposition processes.
While other modifications of the invention and variations thereof which may be employed within the scope of the invention, have not been described, the invention is intended to include such modifications as may be embraced wi~hin the following claims.
, ~ . .
' , - ' :,' ' , ' :' ~ ' ' , ' , . , ' :
Claims (23)
1. A fluid containment article for containing hot hydrocarbon fluid comprising a substrate having a surface adapted for contact with the hydrocarbon fluid wherein the surface comprises a liner selected from the group consisting of a catalytically-active diffusion barrier material which catalyzes thermal decomposition in the hydrocarbon fluid to promote the formation of coke, the coke being substantially non-adherent to the liner, and a catalytically-inactive diffusion barrier material which is inert to thermal decomposition in the hydrocarbon fluid and inhibits the formation of coke, the catalytically-active and catalytically-inactive diffusion barrier materials inhibiting the formation of gum, sulfur compounds or other decomposition impurities or mixtures thereof formed by thermal decomposition of the hydrocarbon fluid, the liner material being a physical diffusion barrier located between the substrate and the hydrocarbon fluid.
2. The fluid containment article of Claim 1 wherein the liner material is deposited by chemical vapor deposition.
3. The fluid containment article of Claim 1 wherein the catalytically-active and catalytically inactive diffusion barrier material is a metal oxide.
4. The fluid containment article of Claim 3 wherein the liner material is deposited by chemical vapor deposition.
5. The fluid containment article of Claim 3 wherein the metal oxide is amorphous.
Dkt. No. 13-DV-10,367
Dkt. No. 13-DV-10,367
6. The fluid containment article of Claim 5 wherein the liner material is deposited by chemical vapor deposition.
7. The fluid containment article of Claim 5 wherein the catalytically-inactive amorphous metal oxide is tantalum oxide.
8. The fluid containment article of Claim 7 wherein the liner material is deposited by chemical vapor deposition.
9. The fluid containment article of Claim 5 wherein the catalytically-active amorphous metal oxide is zirconium oxide.
10. The fluid containment article of Claim 9 wherein the liner material is deposited by chemical vapor deposition.
11. The fluid containment article of Claim 1 comprising a fuel injector.
12. The fluid containment article of Claim 1 comprising a fuel valve.
13. The fluid containment article of Claim 1 comprising a heat exchanger surface.
14. The fluid containment article of Claim 13 comprising a heat exchanger surface in a combustor wall.
Dkt. No. 13-DV-10,367
Dkt. No. 13-DV-10,367
15. A method of preventing the deposit of thermal decomposition products in a hydrocarbon fluid on a metal surface of a device adapted to contain the hydrocarbon fluid comprising applying to the metal surface a layer of diffusion barrier material which is inert to chemical formation of thermal decomposition products in the fluid.
16. The method of Claim 15 wherein the layer of diffusion barrier material applied to the metal is a metal oxide.
17. The method of Claim 16 wherein the metal oxide is amorphous.
18. The method of Claim 17 wherein the layer of amorphous metal oxide diffusion barrier material applied to the metal is amorphous tantalum oxide.
19. A method of preventing the deposit of thermal decomposition products in a hydrocarbon fluid on a metal surface of a device adapted to contain the hydrocarbon fluid comprising applying to the metal surface a layer of diffusion barrier material which catalyzes thermal decomposition in the hydrocarbon fluid to promote the formation of coke while simultaneously inhibiting the formation of gum, sulfur compounds and other decomposition impurities, the coke being substantially non-adherent to the diffusion barrier material.
20. The method of Claim 19 wherein the layer of diffusion barrier material applied to the metal is a metal oxide.
21. The method of Claim 20 wherein the metal oxide is amorphous.
- 29 - 13-DV-10,367
- 29 - 13-DV-10,367
22. The method of Claim 21 wherein the layer of amorphous metal oxide diffusion barrier material applied to the metal is amorphous zirconium oxide.
23. The invention as defined in any of the preceding claims including any further features of novelty disclosed.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US67392491A | 1991-03-25 | 1991-03-25 | |
| US673,924 | 1991-03-25 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2062024A1 true CA2062024A1 (en) | 1992-09-26 |
Family
ID=24704645
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002062024A Abandoned CA2062024A1 (en) | 1991-03-25 | 1992-02-27 | Fluid containment article for hot hydrocarbon fluid and method of preventing fuel thermal decomposition deposits |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2062024A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0589679A2 (en) * | 1992-09-22 | 1994-03-30 | General Electric Company | Method of preventing fuel thermal degradation deposits |
| EP0607651A1 (en) * | 1993-01-15 | 1994-07-27 | General Electric Company | Prevention of fuel thermal degradation deposits |
| EP0608081A1 (en) * | 1993-01-15 | 1994-07-27 | General Electric Company | Coated articles and method for the prevention of fuel thermal degradation deposits |
| CN112849416A (en) * | 2019-11-12 | 2021-05-28 | 通用电气公司 | System and method for removing heat from an aircraft component |
-
1992
- 1992-02-27 CA CA002062024A patent/CA2062024A1/en not_active Abandoned
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0589679A2 (en) * | 1992-09-22 | 1994-03-30 | General Electric Company | Method of preventing fuel thermal degradation deposits |
| EP0589679A3 (en) * | 1992-09-22 | 1994-07-06 | Gen Electric | Method of preventing fuel thermal degradation deposits |
| EP0607651A1 (en) * | 1993-01-15 | 1994-07-27 | General Electric Company | Prevention of fuel thermal degradation deposits |
| EP0608081A1 (en) * | 1993-01-15 | 1994-07-27 | General Electric Company | Coated articles and method for the prevention of fuel thermal degradation deposits |
| CN112849416A (en) * | 2019-11-12 | 2021-05-28 | 通用电气公司 | System and method for removing heat from an aircraft component |
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