Fuel and related compositions – Liquid fuels – Heterocyclic carbon compound containing a hetero ring having...
Patent
1997-09-17
1999-09-28
McAvoy, Ellen M.
Fuel and related compositions
Liquid fuels
Heterocyclic carbon compound containing a hetero ring having...
44404, C10L 122, C10L 118
Patent
active
059580895
DESCRIPTION:
BRIEF SUMMARY
This invention relates to additives for improving the lubricity of fuel oils such as diesel fuel oil. Diesel fuel oil compositions including the additives exhibit improved lubricity and reduced engine wear.
Concern for the environment has resulted in moves to significantly reduce the noxious components in emissions when fuel oils are burnt, particularly in engines such as diesel engines. Attempts are being made for example to minimise sulphur dioxide emissions resulting from the combustion of fuel oils. As a consequence attempts are being made to minimise the sulphur content of diesel fuel oils. Although typical diesel fuel oils have in the past contained 1% by weight or more of sulphur (expressed as elemental sulphur) it is now considered desirable to reduce the level, preferably to 0.05% by weight and, advantageously, to less than 0.01% by weight.
The additional refining of the fuel oils, necessary to achieve these low sulphur levels, often results in reductions in the level of other polar components. In addition, refinery processes can reduce the level of polynucleararomatic compounds present in such fuel oils.
Reducing the level of one or more of the sulphur, polynucleararomatic or polar components of diesel fuel oil can reduce the ability of the oil to lubricate the injection system of the engine so that, for example, the fuel injection pump of the engine fails relatively early in the life of an engine. Failure may occur in high pressure fuel injection systems such as high pressure rotary distributors, in-line pumps and injectors.
The problem of poor lubricity in fuel oils is likely to be exacerbated by the future engine developments aimed at further reducing emissions, which will have more exacting lubricity requirements than present engines. For example, the advent of high pressure unit injectors is anticipated to increase the fuel oil lubricity requirement and hence the demands on lubricity additives.
Environmental concerns are also encouraging the reduction in high-boiling components of fuel oils. Whereas middle distillate fuel oils typically have a 95% distillation point of up to 380.degree. C. or even higher, moves to reduce this point to 360.degree. C. or even 350.degree. C. or lower are gaining momentum.
This reduction in the 95% distillation point has the result of limiting or excluding the presence of some naturally-occurring heavy n-alkanes from fuel oils.
Lowering the levels of both polynucleararomatic compounds and some heavy n-alkanes can alter the physical properties of the resulting fuel oils. It has now been found that lubricity additives hitherto used in the art and particularly those which are esters are poorly soluble in such fuel oils, particularly at low temperatures, leading to partial precipitation of these additives. As a result, the lubricity additives may not reach their intended sites of action further along the fuel system.
Furthermore, there is a continual need for additives with improved lubricity performance.
It has now been found that the lubricity of fuel oils, especially low sulphur, low 95% distillation point fuel oils can be improved by the use of an additive composition which also exhibits improved solubility in the fuel oil.
GB 1,310,847 discloses additives for cleaning the fuel systems of liquid fuel-burning engines and other fuel burning devices, the additive comprising a dispersant which may be an acylated nitrogen compound, and an oxy compound which may be an ester of a glycol, polyglycol, monoether glycol and monoether polyglycol with a mono carboxylic acid containing up to twenty carbon atoms.
WO-A-92/02601 discloses deposit control additives for fuels which comprise a polymer or copolymer of an olefinic hydrocarbon, a polyether, an N-substituted polyalkenyl succinimide of a polyamine and a polyol ester based on neopentyl glycol, pentaerythritol or trimethylol propane with corresponding monocarboxylic acids, an oligomer ester, or a polymer ester based on dicarboxylic acid, polyol and monoalcohol. The olefin polymer, polyether and ester form a carrier fluid
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Caprotti Rinaldo
Dillworth Brid
Exxon Chemical Patents Inc.
McAvoy Ellen M.
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