Fuel and related compositions – Liquid fuels – Emulsion fuel
Reexamination Certificate
2002-04-01
2003-03-18
Toomer, Cephia D. (Department: 1714)
Fuel and related compositions
Liquid fuels
Emulsion fuel
C044S385000, C044S403000, C044S411000
Reexamination Certificate
active
06533829
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to an additive which can be used with good results to stabilize liquid fuels which, beside liquid hydrocarbons (such as petrol, gasoline, diesel fuel, kerosine) utilised as fuels for internal combustion engines, also contain water. The invention also relates to fuels stabilized with said additive, as well as to a process for preparing thereof. The invention also relates to the use of said additives to stabilize water-containing liquid hydrocarbon fuels, as well as to the use of such stabilized fuels to operate internal combustion engines.
BACKGROUND OF THE INVENTION
It is known that the performance of internal combustion engines can be increased by adding water to the liquid organic fuel. The amount of liquid organic fuel required to operate the engine can also be reduced by adding water to it. A favourable consequence of the above is that the octane number of gasoline can be increased by adding water to it, and, as a second favourable consequence, environmental damages resulting from the combustion of organic fuels can be suppressed.
Although since about 60 years efforts have been taken to exploit the above advantages as full as possible, by the solutions known before it could be done only on the expense of very high investments, which sometimes have not been in proportion to the attained results. Thus, for example, during the second world war—in order to increase the performance—such a technical solution was applied for Focker type fighters where water was injected into the cylinders of the engine by a separate injector after the electric ignition. Indeed, this solution resulted in a 10-15% increase in performance, however, to operate the engines, it was required to modify their structure and to install an exactly adjusted injector. With aircrafts it was a considerable further disadvantage that mounting of the injector and of a separate water tank resulted in an undesired increase in weight.
According to the method disclosed in EP 0 177 484 A1 a dispersion of fuel and water has been injected into the combustion chamber of the engine. For this end considerable technical modifications had to be performed on the structure of the engine, and various additional structural elements (such as heat exchanger, collector, etc.) had also to be installed. The solution disclosed in EP 0 142 580 A1 is based on the same principle; it differs from the previous one essentially only in the structural modifications performed on the engine.
According to the method disclosed in EP 0 311 877 A2 water has been introduced into the combustion chamber as steam rather than as a dispersion formed with the fuel. This requires the use of a specific cylinder head, and several accessories hadd also to be installed to the engine.
Thus, the solutions listed above have the common disadvantage that both the engine and its technical surroundings should be modified considerably which, on one hand, runs with high costs, and, on the other hand, the thus-modified structure cannot be operated with a conventional fuel any more. Structural modifications were required primarily because the aqueous fuel could not be stabilized for a sufficiently prolonged period of time which would enable a safe operation, thus one had to form the water/fuel mixture directly in the combustion chamber from its components. These solutions did not attain a widespread practical use, just because of the specific structural requirements discussed above.
U.S. Pat. No. 5 156 114 discloses the use of liquid fuels containing 20-80 v/v % of water in internal combustion engines. This solution also requires a modification of the engine in such a way that a hydrogen-evolving catalyst should be placed into the combustion chamber, generally as the electrically negative pole of the ignition. This hydrogen-evolving catalyst converts at least part of the water, introduced together with the organic fuel, into hydrogen and oxygen, and the evolved hydrogen is combusted together with the organic fuel. The resulting power surplus, together with the power surplus resulting from steam expansion, fully compensates for the power loss which arises from lowering the amount of the organic fuel.
This patent discusses primarily the use of aqueous methanol or aqueous ethanol as fuel, where inhomogenity problems do not emerge, since both of the organic components are fully miscible with water. In one of the examples the author also refers to the use of aqueous diesel fuel, and remarks here that the fuel mix should be used as an emulsion, and additional bypipes should be fit to the engine in order to avoid undesirable water condensation. No data can be found in this paper on the stability of the emulsion comprising water and organic hydrocarbon fuel; and only a very general information is given on the applicable surfactants, saying that all of the commercially available substances which assist hydrocarbon fuels to be dispersed in water fit for this purpose.
One of the disadvantages of the solution disclosed in the cited paper is that the engine (and, when hydrocarbon fuels are used, its accessories, too) should still be modified, although these modifications are no more disturbing when the engine is operated with hydrocarbon fuel alone. As a much more serious disadvantage, the engine can be operated either with a fully water-miscible fuel type (i.e. with alcohol or aqueous alcohol) or with a water-immiscible fuel type (i.e. with a hydrocarbon or with an emulsion of water and hydrocarbon), because any eventual mixing of the two fuel types immediately causes stability problems and operational disturbances associated therewith. Thus when the fuel type actually filled into the tank is not available at the refuelling station, either the content of the tank should be consumed completely before changing the fuel type, or the vehicle should be equipped with two separate fuel tanks. Of course, such stability problems may also arise when the hydrocarbon-based fuels already present in the tank and to be topped up have different water contents. As a serious insufficiency, the cited paper does not give any actual solution on the stabilization of water-containing liquid hydrocarbon fuels. Thus, despite of its advantages, the solution disclosed in the cited patent has not become widespread with internal combustion engines operated with liquid hydrocarbons.
In our previous international patent application No. PCT/HU97/00029 we have disclosed a method for stabilizing aqueous mixtures of liquid hydrocarbon fuels with various surfactants or surfactant mixtures. By a proper selection of the emuls-fying agents and combinations thereof we succeeded to form aqueous liquid hydrocarbon fuel compositions which were stable for a relatively prolonged period of time and which could be directly combusted in all types of the widely used internal combustion engines, without requiring the engine to be modified or additional accessories to be installed. In this way all of the favourable consequences of water introduction (increase in power, savings in hydrocarbons, increase in octane number, etc.) can be well exploited without modifying the structures of the existing engines.
Upon a more accurate evaluation of the demands it appeared, however, that, with regard to the requirements of operational safety, transporting and storage, only those water-containing liquid hydrocarbon fuels can find commercial utility which, in addition to providing all the advantages attributable to the presence of water, are fully clear, transparent and free of sediments, retain this state for several years, and are relatively insensitive to being mixed with a fuel of other water content (“topping up”). The compositions disclosed in the cited patent application do not fully satisfy these increased requirements.
Continuing our research work we have found, unexpectedly, that aqueous liquid hydrocarbon fuels which fully meet the above requirements can be obtained when they are stabilized with an additive comprising
an alcohol of 5-10 carbon atoms,
0.5-3 parts by weight, calculated for 1 p
Bertha András
Fülöp Levente
Friedman Susan J.
Toomer Cephia D.
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