A FUEL MIXTURE FOR SPIRIT FIRED BOILING AND HEATING APPARATUS

Abstract: A fuel mixture for spirit fired boiling and heating apparatuses. It consists of approximately 3-20 percent by volume of water, ethanol and methanol of a mixing ratio of approximately 1/1 - 4/1, and denaturing agents. The fuel mixture is available in the form of a two component system one component thereof consisting of methanol, water and denaturing agent, and the other component thereof being usual commercial spirit of the type "T-red".

Description: A fuel mixture for spirit fired "boiling an heating apparatus The present invention relates to a fuel mixture for spirit fired boiling and heating apparatus, preferably of the spirit stove type withou a specific gasifier. Examples of such spirit stoves are disclosed in the Swedish patent No. 331 333. The following desiderata can be made with respect to the properties of a fuel for spirit stoves. Thus, it should give a soot-free combustion, have a relatively high boiling point and energy density, and a relatively low water content. Furthermore, it should be easily available for technical use and cheap to manufacture and sell. It is also important tha it does not unfavourably influence the controlability of the flame. From the point of view of health the fuel should not be fatal to consume or inhale. To prevent misuse to the greatest possible extent the fuel should have a disgusting taste and smell, and a characteristic look. Likewise from the point of view of health and hygiene the fuel should finally give no or insignificant smell at complete combustion, but a smell signal at incomplete combustion. Since long usual commercial spirit of the type "red spirit", "T- spirit", "T-red" and similar is used as a fuel for spirit stoves. As a rule these spirit grades contain approximately 95% by volume of ethanol and for the rest water rests from the spirit manufacture and denaturating agents. This fuel during certain conditions of use primarily has the draw back that it involves comparably strong blackening during combustion. The blackening problem is old but has not, in spite of efforts during many years, hitherto found its solution. The foremost difficulty at producing a new fuel is to combine, in a satisfactory way, as many as possible of the above stated desiderata. A simple way of obtaining a minimum of blackening is to use methanol instead of ethanol. It has turned out that this type of alcohol at combustion gives a very soot-free flame. Methanol has, however, two serious drawbacks. Firstly it involves well-known health hazards, among which can be mentioned the risk for blindness also at consumption of smal quantities, and the risk for death at consumption of quantities exceeding as little as 5 cl. Secondly a great number of spirit fired cooking and heating apparatus are designed to be fired with a fuel - i.e. normally usual commercial spirit - which has a boiling point of approximately 78°C. To use methanol with its boiling point of approximately 65°C in such available apparatus involves problems and risks due to early evaporation.' One object of the invention is to provide a new fuel for cooking and heating apparatus of the spirit stove type which is almost free of blackening at combustion, and has a boiling point that makes it usable fo available spirit stoves fired with commercial spirit, i.e. at least 70°C, and that is cheap. In a surprisingly simple way this object has turned out to be obtainable by a alcohol-water mixture which contains 3-20 percent by volume of water, the alcohol then including ethanol and methanol. While preserving the freedom from blackening of the methanhol at combustion, a boiling point lying at approximately 70°C or thereabove is obtained with a mixture of methanol and 15-40% by volume of water. A fuel lying within this mixture area gives a very fine combustion. In addition this fuel mixture becomes very cheap due to the fact that methanol in itself is a very cheap starting material. A drawback is, however, the lower energy density of methanol that furthermore decreases with increasing water content in the mixture. To this mixture emetic and similar is added that shall prevent unintentional consumption or misuse. In order to minimize the health risks with the mixture it contains ethanol to such an amount that an alcohol mixture is obtained which includes at least approximately one part by volyme of methanol and at the most approximately four parts by volyme of ethanol. At medical treatment of methanol poisoning ethanol is used which, when supplied afterwards in comparably great amounts to the patient, prevents forming of the harmful formic acid. At unintentional consumption of the fuel mixture to which ethanol has thus been added, probably very small quantities will be resorbed, due to the added denaturating agents. In this case the particular harmful effects of methanol should be essentially prevented by the addition of ethanol. At intentional consumption there may be a question of greater amounts managing to be resorbed despite the addition of denaturing agents but also here the addition of ethanol is of very great importance until medical treatment is started. For an adult a mouthful of methanol corres¬ ponds to up to 5 cl which is also stated in some connections to be the least dose that can be fatal at consumption. If the portion of methanol i the fuel mixture is of an order of magnitude of 50% this accordingly implies that the portion of methanol in a mouthful of the mixture is approximately 2.5 cl, the harmful effects of which to a very great extent are directly counteracted by the addition of ethanol, the neutralizing effect of which is increased with the added amount of ethanol. In addition to other advantageous properties the suggested fuel mixture has an essentially higher energy density than pure methanol whi should be considered as important. The ethanol addition also increases the boiling point of the mixt and thereby decreases to a certain amount the need for additional water, which shall be discussed more closely below. The upper limit of the ethanol addition, i.e. approximately four parts of ethanol for one part of methanol, is the limit over which the mixture markedly begins to soot at combustion. It has, however, according to the invention, been found that addition of water in itself decreases the blackening tendencies. The addition of water in the mixture acts in a negative direction on the energy density. In practice this appears by an increase of the boiling time which, while being fully objectively noticeable at greater water additions, is practically negligible and is normally not noticed subjectively. At use of spirit stoves evaporation of the fuel can vary within an interval which will here henceforth be called sensitive area. For conventional fuels, i.e. usual commercial spirit, the sensitive area lie between 76 and 79°C. At the stated highest limit for the ethanol addition it has turned out that the mixture according to the invention requires a water additio of at least an order of magnitude of 3% to secure that the lower limit for the sensitive area without doubt shall exceed 70°C. Tests have shown that the water addition gives a shift of the sensitive area towards a higher boiling point without implying obvious drawbacks with respect to other combustion properties if the water addition is held between certain limits. Furthermore, under certain circumstances, the water addition can involve a decreased blackening tendency as has been explained above. The tests have shown that the wate addition should be 3-10%. A great number of sooting tests have been carried out and below a representative selection is given tabulated. Thus, a number of fuel mixtures with a varying ratio methanol/ethanol have been burnt in spirit stoves of a commercially available type, the sooting tendency on a boili vessel located on the spirit stove having then been studied. Table 1 Composition of the fuel: Sooting tendency: % by volume of methanol (M.) + % by volume of ethanol (E) 7,9 M + 92,1 E Strong sooting 12,7 M + 87,3 E 17,6 M + 82,4 E Reduced, but still strong sooting 22,4 + 77,6 E Greatly reduced, but still fully noticeable sooting tendency 27,2 M + 72,8 E Insignificant sooting 27 M + 63 E + 10% by weight of water Table 2 The following tests illustrate how the limits for the sensitive area vary with the composition of the fuel. The proportion of ethanol has been deciding for the magnitude of the denaturing additive. Test Fuel composition: % by volume of methanol Sensitive area No. (M) + % by volume of ethanol (E) + % by °C volume of water (V) + percent by volume of denaturing agent 1 85 M + 15 V 67-71 2 70 M + 30 V 71-74 3 60 M + 40 V 71-75 4 50 M+ 45 E + 3 V + 2 denaturing agent 70-73 5 34 M + 60 E + 3 V + 3 71-74 6 30 M + 64 E + 3 V + 3 73-76 7 27 M + 67 E + 3 V + 3 73-76 8 22 M + 72 E + 3 V + 3 73-76 9 46 M + 42 E + 10 V + 2 74-74 10 32 M + 55 E + 10 V + 3 74-76 11 .24 M + 63 E + 10 V + 3 76-77 12 20 M + 67 E + 10 V + 3 76-77 From table 1 it follows that the mixture of methanol and ethanol should contain at most approximately four parts of ethanol on one part of methanol if blackening is to be avoided, without addition of water. It should, however, be strongly emphasized that without a water addition fuel is obtained which is much inferior with respect to its control- ability. Addition of water thus improves the controlability of the flame with the methanol-ethanol mixture. From table 2 it appears that the mixture requires a certain amount of water for keeping the sensitive area on a desired level. I.a. it turn out that at the content of ethanol that is maximally allowable from the point of view of sooting, the mixture should also include an amount of water of an order of magnitude of 3-20 percent by volume, preferably 3-1 percent by volume in order that the sensitive area will be kept on the desired level. Addition of certain denaturing agents has turned out to involve a sooting tendency. To allow space also for the desired additions of denaturing agents a mixture suitable from several points of view shoul contain 1.85-2.55 parts, preferably at least 2 parts of ethanol for 1 par of methanol. The stated limits for the ethanol-methanol ratio correspond, expressed in another way, to a methanol content in the alcohol mixture of 28-35% and 3-15%, preferably 5-10 percent by volume of water. Preferably approximately 2.5 parts of ethanol on 1 part of methanol plus 3-10 percen by volume of water, the sensitive area then obtained being 73-76°C The choice of denaturing agent essentially affects the other mixture ratios. From the above it should have occurred that the invention provides an almost soot-free fuel mixture which under certain operational conditions is comparable with the commercial spirit thus far usually available with respect to boiling point and energy density and which furthermore has a satisfactorily low water content. The health risks of the methanol are essentially decreased by a considerable addition of ethanol that is the medical cure against methanol poisonings. For alcohol-political reasons there can, in certain countries due to a farreaching particular consideration for alcohol abusers, arise problems with respect to marketing a pre-mixed product including ethanol and methanol. Preferably the fuel mixture according to the invention can then be available for sale based upon a two component system. One component then preferably consists of methanol with addition of denaturin agent. To the methanol approximately 50 mg bitrex pro kilo methanol can thus be added as well as approximately 1.5 mg of the colour agent crysta violet C25H3 Q GIN3. Furthermore, this component includes 10-30%, preferably 10-15% of common water. The other component of the two component system can thereby quite simply be technical commercial spirit, e.g. 96% of spirit of the type "T-red", which is then by two parts mixed with one part of the first component. More generally the mixture ratio could lie within the limits 1/1-1/4 for component 1/component 2. By the addition of denaturing agent in the form of the bitter agen bitrex and a conspicuous colour agent differing from usual methanol and water unintentional consumption of methanol is practically made impossib by changing its colourless, relatively tasteless character. The addition of 10-15% of common water in a desirable way increases the boiling point of the completed mixture and the possibilities of a good controlability the spirit stove.

Claims: Claims 1. A fuel mixture for spirit stoves without a specific gasifying device, characterized in that it consists of water, ethanol, methanol and denaturing agent, of which the content of water is 3-20 percent by volume, ethanol and methanol is included at a mixture ratio of approximately 1/1 - 4/1 and the denaturing agent is added with an amount that shall prevent unintentional consumption or misuse of the mixture. 2. A mixture according to claim 1, characterized in that said mixture ratio is 1.85/1 - 2.55/1. 3. A mixture according to claim 2, characterized in that said mixture ratio is at least 2/1 and the water content 3-10% by volume. 4. A mixture according to claim 2, characterized in that said mixture ratio is approximately 2.5/1 and the water content 3-10 percent by volume. 5. A mixture according to any of claims 1 and 2, characterized in that the water content is 3-15 percent by volume. 6. A two component system intended to be used for mixing a fuel mixture according to any of the preceding claims, characterized in that one component thereof consists of methanol with an addition of denaturin agent and water of an order of magnitude of 10-30 percent by volume, the other component of the system being denatured commercial spirit. 7. A system according to claim 6, characterized in that said one and other components are in a mixing ratio of an order of magnitude of 1/1 - 1/4. ' 8. A system according to claim 6, characterized in that as a denaturing agent is added bitrex of an order of magnitude of 50 mg pro kilo methanol and a colour agent, e.g. crystal violet of an order of magnitude of 1.5 mg 9. A two component system intended to be used for mixing a fuel mixture for spirit stoves without a specific gasifying device, characterized in that one component thereof consists of methanol with an addition of denaturing agents, and water of an order of magnitude of 10-30 procent by volume the other component of the system consisting of denatured commercial spirit. 10. A system according to claim 9, characterized in that said one and other components have a mixing ratio of an order of magnitude of 1/1 -1/4.

Inventors: BOIJ KARL OSKAR ARNE, BOIJ, KARL, OSKAR, ARNE
Applicants: BOIJ KARL O A, BOIJ, KARL, OSKAR, ARNE
Application year: 1985
Main classification: C10L1
IPC codes: C10L1