Fuel and related compositions – Liquid fuels – Containing organic -c
Patent
1996-12-05
1998-06-30
Howard, Jacqueline V.
Fuel and related compositions
Liquid fuels
Containing organic -c
44390, 44405, 44412, C10L 114, C10L 122
Patent
active
057727058
DESCRIPTION:
BRIEF SUMMARY
This invention relates to fuel oils, and to the use of additives to improve the characteristics of fuel oils, more especially of diesel fuel and kerosene.
Environmental concerns have led to a need for fuels with reduced sulphur content, especially diesel fuel and kerosene. However, the refining processes that produce fuels with low sulphur contents also result in a product of lower viscosity and a lower content of other components in the fuel that contribute to its lubricity, for example, polycyclic aromatics and polar compounds. Furthermore, sulphur-containing compounds in general are regarded as providing anti-wear properties and a result of the reduction in their proportions, together with the reduction in proportions of other components providing lubricity, has been an increase in reported failures of fuel pumps in diesel engines using low-sulphur fuels, the failure being caused by wear in, for example, cam plates, rollers, spindles and drive shafts.
This problem may be expected to become worse in future because, in order to meet stricter requirements on exhaust emissions generally, high pressure fuel pumps, including in-line, rotary and unit injector systems, are being introduced, these being expected to have more stringent lubricity requirements than present equipment, at the same time as lower sulphur levels in fuels become more widely required.
At present, a typical sulphur content in a diesel fuel is about 0.25% by weight. In Europe maximum sulphur levels are being reduced to 0.20%, and are expected to be reduced to 0.05%; in Sweden grades of fuel with levels below 0.005% (Class 2) and 0.001% (Class 1) are already being introduced. A fuel oil composition with a sulphur level below 0.20% by weight is referred to herein as a low-sulphur fuel.
The present invention is based on the observation that a cold flow improver enhances the lubricity of a low-sulphur fuel.
In a first aspect of the invention, there is provided the use of a cold flow improver to enhance the lubricity of a fuel oil composition having a sulphur content of at most 0.2% by weight, more especially of at most 0.05% by weight.
In a second aspect of the invention, there is provided a process for the manufacture of a petroleum based fuel oil of enhanced lubricity, which comprises refining a crude oil to produce a fuel oil of low sulphur content, and blending a cold flow improver with the refined product to provide a fuel oil composition with a sulphur content of at most 0.2% by weight, preferably of at most 0.05% by weight, and having a lubricity such as to give a wear scar diameter, as measured by the HFRR test (as hereinafter defined) at 60.degree. C. of at most 500 .mu.m, such as at most 450 .mu.m, preferably at most 380 .mu.m, more preferably at most 350 .mu.m.
Advantageously, the petroleum-based fuel oil is a middle distillate fuel oil.
In a third aspect of the invention, there is provided a composition comprising a major proportion of a petroleum-based fuel oil and a minor proportion of a cold flow improver comprising an oil-soluble polar nitrogen compound carrying one or more substituents of the formulae >NR.sup.13, where R.sup.13 represents a hydrocarbyl group containing 8 to 40 carbon atoms, which substituent or one or more of which substituents may be in the form of a cation derived therefrom, the sulphur content of the composition being at most 0.2% by weight. Advantageously, the sulphur content is at most 0.05% by weight.
Advantageously, the petroleum-based fuel is a middle distillate fuel oil.
Said polar nitrogen compound may be used in combination with an ethylene-unsaturated ester copolymer flow improver.
Advantageously, the composition resulting from the use of the first aspect, and the composition of the third aspect of the invention have a lubricity as defined with reference to the second aspect.
As used herein, the term "cold flow improver" refers to any additive which will lower the vehicle operability temperature relative to untreated base fuel, as evidenced, for example by lowering the pour point, the cloud point
REFERENCES:
patent: 3092474 (1963-06-01), Ebner
patent: 3166387 (1965-01-01), Ebner
patent: 4127139 (1978-11-01), Sweeney
patent: 4127140 (1978-11-01), Sweeney
patent: 4708993 (1987-11-01), Naiman et al.
patent: 5156655 (1992-10-01), Baillargeon et al.
Exxon Chemical Patents Inc.
Howard Jacqueline V.
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