| Fuel composition -> Monitor Keywords |
|
|
  Fuel compositionRelated Patent Categories: Fuel And Related Compositions, Liquid Fuels (excluding Fuels That Are Exclusively Mixtures Of Liquid Hydrocarbons), Organic Oxygen Compound Containing (e.g., Alicyclic Alcohols, Hypochlorites, Etc.)Fuel composition description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060101711, Fuel composition. Brief Patent Description - Full Patent Description - Patent Application Claims
FIELD OF THE INVENTION [0001] The present invention relates to fuel additives. In particular the present invention relates to use of film-forming additives to inhibit and/or prevent cavitation damage on pumping in blends of fuel alcohol with diesel fuel. BACKGROUND AND PRIOR ART [0002] Internal combustion engines which function through the medium of compression ignition, conventionally known as diesel engines, are well known to those skilled in the art to generate a significant level of particulate matter during the combustion process. Diesel particulates are formed through the combustion or pyrolysis of hydrocarbon fuels typically known as middle distillates, and typically boiling in the temperature range 180.degree. C. to 360.degree. C. Particulates in the exhaust of a diesel engine comprise inorganic ash due to engine wear particles and the combustion products of lubricant oil additives, sulphur containing compounds due to the sulphur in diesel fuel and hydrocarbons from incomplete combustion. These hydrocarbons may be further classified as either soluble material or solid matter, i.e. carbonaceous soot. The soluble hydrocarbon portion of the particulate matter will frequently be described by those skilled in the art as the soluble organic fraction (SOF). [0003] The particulate matter described above may comprise particles so small as to be invisible to the naked eye. However, diesel engines are also known to emit visible smoke, which represents the obscuration of visible light by clouds of larger particles. These larger particles, also called accumulation particles, may arise from condensation and/or agglomeration of smaller particles, also known as nucleation particles. The visual impact which black exhaust smoke from diesel engine exhausts may have on the beholder is almost universally negative. Black exhaust smoke is perceived as a serious source of air pollution resulting in damage to buildings and other property. In addition, all the above-described particulate emissions are also widely understood to represent a hazard to human health. [0004] Governments in many countries have enacted legislation to reduce permitted levels of particulate emissions from diesel engines over recent years. Engine manufacturers have responded to the legislation with the result that in many countries new diesel engines consistently emit lower levels of exhaust particulate matter than older engine designs. However one of the attractive features of the diesel engine for operators and users is its robustness and long life. Diesel engines may be in use for ten, fifteen or twenty years, or, in exceptional cases, even longer. These older engines, while providing very satisfactory service for vehicle owners or operators, nevertheless continue to emit pollutants, in particular particulates and visible smoke, at levels at least as high as when new. [0005] One option which is attractive to governments wishing to improve air quality, is to alter fuel specifications so that all vehicles, as opposed to merely the newer vehicles which are of improved design, produce lower pollution levels. One way in which this can be achieved, is to blend a fuel alcohol such as ethanol into diesel fuel. A blend of ethanol and diesel is commonly known as Ediesel. [0006] The effect of Ediesel on exhaust emissions is subject to some debate and is known to vary between engines of different types. Nevertheless, the most pronounced effect is often found to be in respect of particulate and smoke emissions, which are frequently judged to be the most damaging pollutants emitted by diesel engines. There is thus interest in blends of fuel alcohol and diesel such as Ediesel in many countries of the world, particularly where the diesel vehicle fleet comprises a significant population of older vehicles with unacceptably high particulate emissions. [0007] An additional advantage provided by blends of a fuel alcohol and diesel is the possibility of manufacturing the fuel alcohol, in particular ethanol, initially from renewable products, including waste products of agriculture. This capability provides the opportunity to extend expensive fossil fuel sources, which often need to be imported. Blending fuel alcohol produced from indigenous and renewable sources into diesel fuel can thus make a major and valued contribution to a nation's balance of payments. [0008] The addition of a fuel alcohol to diesel is known to alter the characteristics and physical properties of the base diesel fuel. For example, ethanol boils at a much lower temperature than diesel fuel, whose typical boiling range lies between 180.degree. C. and 360.degree. C. When ethanol is added to diesel fuel, the initial boiling point will be reduced very significantly. This is illustrated in Table 1, which contains data obtained with middle distillates alone and combined with ethanol. TABLE-US-00001 TABLE 1 Distillation characteristics of middle distillate fuels with and without ethanol. ULSD3 ULSD3 + Kerosene + Distillation diesel 7.5% vol. 7.5% vol characteristics fuel ethanol Kerosene ethanol Initial boiling point .degree. C. 175.5 77.0 151.5 77.5 5% recovd. .degree. C. 207.5 78.5 163.0 80.0 10% recovd .degree. C. 220.5 198.5 165.0 155.5 20% recovd .degree. C. 237.5 226.5 169.5 168.0 40% recovd .degree. C. 262.5 255.0 179.0 175.0 70% recovd .degree. C. 297.5 294.5 197.0 195.5 90% recovd .degree. C. 330.5 332.5 216.5 216.0 Final boiling point .degree. C. 356.0 354.4 235.5 229.5 [0009] As is clear from the data in the table, the inclusion of a relatively small volume of ethanol into either a conventional low sulphur diesel fuel, or a kerosene fuel, produces a very significant reduction in the initial boiling point and the 5-10% recovered temperature values (also known as the "front end" by those skilled in the art). Once the ethanol in the front end has boiled off, the rest of the fuel behaves much like a similar base fuel not containing ethanol, as would be expected. [0010] In order to produce significant and readily-measured exhaust emissions benefits, significant quantities, such as from about 1-30%, preferably 1-20% by volume of a fuel alcohol, such as ethanol, are required. Where such substantial quantities of a fuel alcohol, such as ethanol, are blended into a fuel the alcohol may contain water and/or the composition may become hygroscopic. Diesel fuels are well-known to encounter water during passage through the supply chain. Whatever the source, the presence of water in the fuel can lead to a phase-separation into aqueous and diesel fuel phases with partition of the alcohol between the two. This is particularly prone to occur at low temperatures and leads to considerable operability problems. [0011] To prevent such problems additional additives, such a co-solvent(s) and surfactant(s) are employed. The amounts of each used are, as expected, highly dependant on the particular fuel alcohol, it's water content, anticipated ambient temperatures and, above all, the volume percent alcohol in the fuel. In volume percentage terms, the amounts of each used are-typically similar to the volume percent alcohol and are each rarely less than 1%, although quantities as low as 0.5, 0.2 or even 0.1 percent have been claimed, where meaningful (i.e. detectably emissions-reducing) quantities of alcohol are present. Where such levels of surfactant are present, industry standard wear tests as hereinafter/before described, indicate that no wear problems should be encountered with that fuel. [0012] The practical consequences of the change in fuel volatility where a fuel alcohol is added to diesel fuel in diesel engine fuel systems can be significant, since such fuel systems are usually designed for the volatility characteristics of conventional middle distillates. Diesel injection pumps, for example, function in such a way that the film of fuel on various internal components may be exposed to reduced pressure at times during each rotational cycle. An example of this phenomenon is the contact between the slotted face washer and the claws on the driver shaft which mate with it, on the Bosch VE rotary diesel injection pump. During normal operation, reduced pressure occurs in the region of the liquid film on the surface of these components. With a conventional diesel fuel or other middle distillate boiling between the ranges indicated in Table 1, the local pressure reduction causes no operational problems. However, with the much more volatile front end of the fuel resulting from blending ethanol into diesel fuel, pressure reduction in the liquid film is thought to produce cavitation. [0013] Cavitation, as is known to those skilled in the art, constitutes the formation and collapse of vapour-filled gas in liquid bubbles associated with fluctuations in local pressure. It is well known that prolonged cavitation can result in surface damage to metallic components. Erosion of apparently hard metallic surfaces is a characteristic feature of prolonged cavitation. Where cavitation occurs in a diesel engine fuel system, for example in the fuel injector pump, eroded particles, collectively called wear debris, circulate within the pump. Such wear debris is frequently abrasive. Circulation of wear debris within the pump accelerates the wear process, while continuing cavitation produces further wear debris, itself abrasive, leading to very accelerated wear in such pumps. Examples of very accelerated wear in Bosch pumps through cavitation, when operating on diesel fuel containing ethanol are in the public domain. Bosch has publicised information on the Internet (address www.mercosul.bosch.de/50 EPD/epd32), which not only details accelerated wear in injector pumps, but also indicates cavitation damage to other fuel injection equipment components, such as injector needles and pump pressure valve seats. Similar information has also been publicised in Hart's World Fuels Today on 14.sup.th November 2001. [0014] The present invention alleviates the problems of the prior art STATEMENT OF INVENTION [0015] According to a first aspect, the present invention provides a fuel composition comprising a fuel and a film-forming additive wherein the fuel comprises diesel and a fuel alcohol and wherein the film-forming additive is present in the fuel composition in an amount of less than 0.1 wt %. [0016] According to a second aspect, the present invention provides use of a film-forming additive for inhibiting and/or preventing cavitation in a fuel and/or reducing the effects of cavitation in a fuel, wherein the fuel comprises diesel and a fuel alcohol. [0017] According to a third aspect, the present invention provides a process for supplying a fuel composition to a combustion engine wherein the process comprises (i) pumping the fuel composition with a rotary pump to supply the fuel composition to the combustion engine wherein the fuel composition comprises diesel, a fuel alcohol and a film-forming additive. [0018] It has surprisingly been found that film-forming additives may be used to inhibit and/or prevent cavitation in blends of diesel and a fuel alcohol. Addition of a film-forming additive to a blend of diesel and a fuel alcohol may typically reduce the cavitation-induced surface damage of metallic components in a diesel engine fuel system in which the fuel blend is used. Additionally, use of a film-forming additive in this manner may reduce wear debris generated by cavitation and may also reduce the wear to the diesel engine fuel system and in particular the fuel injection equipment which the wear debris may cause. Thus, use of a film-forming additive according to the present invention, may increase the lifetime of the diesel engine fuel system especially fuel injection equipment components, such as fuel injector pumps, injector needles and pump pressure seat valves. [0019] The recent discovery that fuels containing fuel alcohols could cause damage to diesel engine components was, indeed, surprising. More so was that such fuels could satisfy industry-standard wear tests yet give in-service problems. It has surprisingly been found that film-forming additives may be used to protect engine components from such wear. Without wishing to be bound by theory it is believed that they act to inhibit and/or prevent cavitation in blends comprising diesel and a fuel alcohol [0020] The term "film-forming additive" as used herein, means a substance which, when present in a fuel composition comprising a fuel, the film-forming additive and optional further fuel components, increases the ability of the fuel to form a coating on a metal surface, such as a metal surface within a fuel pump, with which it is contacted. [0021] Particularly useful as a film-forming additive according to the present invention is a substance capable of providing a fuel with which it is contacted with a fuel quality parameter whereby wear between two metal surfaces in contact with each other and with the fuel in a test apparatus is limited to a permitted maximum level. Limitation of wear in a test apparatus may be determined by exceeding a minimum applied load of greater than 2800 g, as in the Scuffing Load Ball-On-Cylinder Lubricity Evaluator method (SLBOCLE--ASTM D 6078). Alternatively, limitation of wear in a test apparatus may be determined by not exceeding a wear limit, as in the High Frequency Reciprocation Rig method (HFRR-ASTM D 6079) of 460 micron wear scar diameter (WSD) at 60.degree. C. Limitation of wear may also be measured using the HFRR equipment under the Coordinating European Council (CEC) F-06-A-96 method, which is very similar to the ASTM D 6079 method, but embodies additional controls on temperature and humidity, and may therefore be expected to provide greater test precision than ASTM D 6079. Continue reading about Fuel composition... Full patent description for Fuel composition Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Fuel composition patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Fuel composition or other areas of interest. ### Previous Patent Application: Additive for solid hydrocarbon fueled direct fired burners, furnaces, open flames and related processes Next Patent Application: Small off-road engine green fuel Industry Class: Fuel and related compositions ### FreshPatents.com Support Thank you for viewing the Fuel composition patent info. IP-related news and info Results in 0.25124 seconds Other interesting Feshpatents.com categories: Canon USA , Celera Genomics , Cephalon, Inc. , Cingular Wireless , Clorox , Colgate-Palmolive , Corning , Cymer , |
||
