Fuel and related compositions – Liquid fuels – Organic compound containing -nc or -cn group
Patent
1988-02-29
1993-09-21
McAvoy, Ellen M.
Fuel and related compositions
Liquid fuels
Organic compound containing -nc or -cn group
44389, 44417, 44418, 44419, 585 2, 585 3, 585 4, 585823, 585824, 585830, C10L 130, C10L 116
Patent
active
052464695
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method and means of preventing degradation in liquid hydrocarbon fuels.
Some liquid fuels particularly distillates are stored in static storages for periods of up to several years.
Over extended periods of time, small but significant changes in fuel properties can occur. Important properties which change with time are colour and insolubles content. Insoluble materials can plug fuel system filters, reduce or alter the fuel flow through engine nozzles and form sludges in the fuel tanks. Formation of insolubles is an indication of chemical reactions in a fuel. Chemical degradation of fuels is an important aspect of fuel stability.
Storage stability of distillate fuels has been of modest concern for fuels made by refining processes based on straight run distillation. However, increasing quantities of heavy crudes and distillation fractions are being run in refineries using cracking processes to increase the yield of middle distillate fuels. The cracked products, which contain chemically unstable species, are blended into straight run streams. The unstable components, although diluted by the blending, still exert a strong influence on insoluble material formation, particularly for long storage periods.
Stabilizing additives have been proposed to reduce the extent of insoluble material formation in middle distillate fuels. Specific additives, such as phenylenediamines and hindered phenols, have been used. These additives have been found to be effective in preventing the formation of gums in gasolines and peroxides in jet fuels. They have been shown to be ineffective in preventing the formation of particulate matter in distillate fuels.
Additive manufacturers' experience with diesel fuels and home heating oils has led them to recommend alkyl amines as stability additives. These effective additives contained alkyl amines, some in conjunction with a metal deactivator (MDA). These observations were made on several straight run distillates as well as 30% blend of catalytically cracked stock (light cycle oil--LCO) in a stable straight run fuel.
U.S. Pat. No. 3,701,641 proposes to stabilise distillate fuels against degradation using a polyamine having 2 to 6 amino groups and 25 to 50 carbon atoms.
Cyclohexylamines have been proposed as distillate fuel stabilizers in U.S. Pat. Nos. 3,640,692, 3,336,124 and 4,040,799 and in French Patent 1441717.
It is an object of this invention to provide a simple alternative means to stabilizing fuels.
To this end the present invention provides a method of stabilizing liquid hydrocarbon fuels which comprises storing the fuel with solids capable of removing from fuel those active elements which catalyse or participate in the degradation reactions.
These insoluble solid additives reduce the amount of fuel degradation material which is suspended in the fuel or deposited on the walls of the container. The solid additives useful in this invention are thought to contain polar sites to enable polar condensation of the active constituents to occur. A solid additive with this capability acts as a preferred deposition site for molecules of insoluble material, and for precursors of insoluble material in the fuel. These precursors are partitioned between the solid additive and the fuel molecules. Reduction of the concentration of these precursors in the fuel reduces degradation of the fuel.
Application of solid additives to the interior of fuel system components for fuel stabilization can be in the form of cellular foams, sponges, mesh, woven fabric, naturally entwined or bound fibre bundles, surface coatings, strips, films, or solids such as powders or particulate material encapsulated in fuel permeable containers. Preferred foams are open cell polyurethane foams or polymeric foams including urea, carbamate, ester or amide groups available as polar sites.
Polyurethane (PU) foam is a solid which possesses high fuel stabilization performance when immersed in fuel during storage. These polymers comprise large numbers of well defined polar functional groups which have aff
REFERENCES:
patent: 2306870 (1942-12-01), Engelhardt
patent: 4032510 (1977-06-01), Floyd et al.
patent: 4339246 (1982-07-01), Yamamura et al.
patent: 4659334 (1987-04-01), Matlach
Arfelli William
Power Alan
Solly Richard
McAvoy Ellen M.
The Commonwealth of Australia
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