Fuel and related compositions – Liquid fuels – Organic oxygen compound containing
Patent
1990-08-22
1993-02-02
Chaudhuri, Olik
Fuel and related compositions
Liquid fuels
Organic oxygen compound containing
44451, C10L 102
Patent
active
051834766
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an ethanol fuel which contains polyalkylene glycol compounds as an ignition-improving agent.
2. Background of the Related Art
In a diesel engine, the combustion air is compressed to about 40 bars, the air reaching a temperature sufficiently high to ignite the diesel oil which is being injected. For gas oil, the temperature of use is specified at 336.degree. C., and for kerosene at 295.degree. C. For anhydrous ethanol, the ignition temperature in air is specified at 558.degree. C., and in oxygen gas at 425.degree. C. Morover, the evaporation of ethanol corresponds to a cooling of air by about 125.degree. C. in a stoichiometric relationship between ethanol and air. Thus, because of the high ignition temperature of the ethanol, it is not possible to use pure ethanol as fuel in a conventional diesel engine.
One way of igniting the ethanol fuel is to provide the diesel engine with spark plugs, but this necessitates extensive modifications to the engine's construction. For conventional diesel engines, a so-called ignition-improving agent, i.e., an agent which serves to lower the ignition temperature of the fuel, has been added to the ethanol. The predominant ignition-improving agent is the group consisting of alkyl nitrates, and the most used substrance is 2-ethylhexyl nitrate, generally abbreviated EHN.
EHN, which has a rather strong and disagreeable odour, is toxic and can be hydrolyzed to nitric acid and 2-ethylhexanol when stored for long periods of time, especially at elevated temperature. The hydrolysis causes a marked lowering of the pH, implying a serious risk of corrosion. A further serious objection to EHN is that the substance contains nitrogen which may increase the emission of nitrogen oxides in the exhaust gases. Therefore, it is generally desirable that EHN and other nitrate-based ignition-improving agents be replaced by an agent which is less hazardous to the environment and has higher stability.
It is also known to add corrosion inhibitors and lubricants to fuels. German Patent Application A1, 3,628,504 describes a fuel mixture of hydrocarbons, an alcohol and a corrosion inhibitor in an amount of up to 5000 ppm. This inhibitor contains a surface active agent, e.g., block polymers of alkylene oxides.
British Patent Application A2, 143,846 discloses the use of 0.005-0.05% by weight of a polyalkylene glycol as a lubricity improver in a diesel fuel based on methanol and/or ethanol.
SUMMARY OF THE INVENTION
It has been found that the above-mentioned disadvantages of EHN can be eliminated if polyalkylene glycol compounds are used as ignition-improving agent in ethanol fuel. The ethanol fuel according to the invention is characterised in that it is in the form of a solution and contains 62-94%, preferably 70-85%, of ethanol, 2-8%, preferably 3-6%, of water, and at least 1%, suitably 2-30%, and preferably 8-25%, of a water-soluble polyalkylene glycol compound which contains 6-50 alkylene oxide units having 2-4 carbon atoms and which has a molecular weight of less than 2500.
Specific examples of such polyalkylene glycol compounds are those which can be expressed by the general formula an alkylene oxide group having 2-3 carbon atoms, at least 20% of all alkylene oxide groups being ethylene oxide groups, and n is an integer selected such that the polyalkylene glycol compound has a molecular weight of from 300 to 2000, preferably from 400 to 1000.
Other useful polyalkylene glycol compounds are compounds in which alkylene oxide having 2-3 carbon atoms has been combined with a thiol compound, a carboxylic acid, a primary or secondary amine, or an alkanol amine in such an amount that the polyalkylene glycol compound will obtain the required molecular weight.
In a conventional diesel engine, the addition of the polyalkylene glycol compound preferably amounts to 12-20% by weight, but by optimizing the engine, e.g., by increasing the compression ratio and/or preheating of inlet air, the addition can be reduced, preferably t
REFERENCES:
patent: 4298352 (1981-11-01), Blysing
patent: 4333739 (1982-06-01), Neves
patent: 4659335 (1987-04-01), Wegner et al.
Pat. Abstracts of Japan, vol. 9, No. 104, (C-279) published Dec. 26, 1984.
Carlsson Goran
Hellsten Martin
Berol Nobel Stenungsund AB
Chaudhuri Olik
Nuzzolillo M.
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