Fuel composition

Abstract

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 %.

Description

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° C. to 360° 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....

AI Technical Summary

Benefits of technology

[0027] A further alternative or additional effect according to the present invention, may be the passivating of freshly-exposed surfaces. Cavitation by ultrasound is well-known for cleaning of metal and other hard surfaces. Enhanced chemical reactivity of metals towards organic species under the influence of power ultrasound is well-known and frequently ascribed to removal of passivating surface oxide or insoluble reaction products. Ediesel and other alcohol-containing diesel fuel blends are widely understood to be more corrosive towards fuel delivery systems than the diesel base fuels. Thus cavitation can lead to exposure of fresh, highly-reactive metal surface to the alcohol containing fuel. The films formed on the metal surface may thus prevent access of the corrosive components to the freshly-exposed surface, and thereby reduce or prevent corrosion.

Problems solved by technology

However, diesel engines are also known to emit visible smoke, which represents the obscuration of visible light by clouds of larger particles.

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.

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.

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.

This is particularly prone to occur at low temperatures and leads to considerable operability 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.

It is well known that prolonged cavitation can result in surface damage to metallic components.

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.

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