US2842431A - Treated fuels - Google Patents

Description

TREATED FUELS I Louie H. Robertson, Elizabeth, N. J.

No Drawing. Application August 24, 1955 Serial No. 539,397

4 Claims. (Cl. 44-24) The present invention relates to treated fuels and a method for preparing the same. More particularly, the present invention relates to a treated fuel Comprising a porous, combustible, adsorbent, carbonaceous solid, such as charcoal in any form, including briquettes, and a wax hydrocarbon.

It is well known that these porous, adsorptive carbonaceous fuels are not readily ignitable when used in relatively small amounts, as when employed as a primary fuel for cooking purposes. To ignite briquettes and chunks of charcoal, it is usually necessary to have present a kindling agent, such as wood and paper which, after prolonged burning, ignite the carbonaceous fuel. This is a relatively lengthy procedure, requiring bulky ignition fuel and entailing substantial amounts of smoke. To provide more rapid ignition, it is also possible to spray the charcoal or briquettes with a light hydrocarbon or oxygenated hydrocarbon auxiliary fuel. This expedient is hazardous and, in cooking, may introduce extraneous odors.

It is the principal purpose of the present invention to supply a treated fuel which is readily ignitable, nonhazardous, and essentially smokeless.

It is a further purpose of the present invention to provide a fuel which, though porous, is essentially dustless and may be handled without blackening the skin or clothing.

A still further purpose and object of the present invention is to provide a treated fuel which is weatherand waterproof.

Other and further objects and purposes of the present invention will be made more clear hereinafter.

In accordance with the present invention a superior treated fuel embodying the aforementioned advantages is prepared by impregnating, under critical controlled time and temperature conditions, the porous carbonaceous fuel with parafiin wax, preferably a wax within a melting point range of 130-140" F.

It has in the past been suggested to coat fuels with wax, principally to afford protective coating to enable shipment without undue breakage or disintegration. These methods usually have comprised spraying the fuels with paraffin wax or treating the fuels with crystalline or amorphous wax solutions, the volatile solvent evaporating and leaving a protective coating of wax upon the surface. This coating is so brittle that it readily scales.

It has also been proposed to coat the surface of carbonaceous fuels with wax by dipping, sprinkling or spraying the molten liquid upon the fuel. Experiments have shown that this is inadequate to produce the fuel of the present invention. It is an important prerequisite of the process of the present invention that the molten wax be adsorbed into and upon the fuel capillaries. A surface coating alone is neither adequate nor desirable. In fact, the fuel of the present invention may have a surface film of wax so thin that it is hardly discernible either to the eye or to the touch.

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In accordance with the present invention, therefore, paraflin wax having a flash point not exceeding 450 F. and a viscosity between about 3.2 and 3.8 centistokes at 210 F., and having preferably a melting point range of about -140? F., is heated in a charging vessel to a temperature of at least F. and preferably to about 1 90l95 F. Thereupon, the solid adsorptive carbonaceous fuel, i. e. charcoal in either loose or briquette form, is immersed in, and allowed to remain submerged in, the wax for a period of no less than five nor more than 20 seconds,.depending upon the porosity 'of the char, This is necessary to provide replacement of the adsorbed gases in the pores of the charcoal by the liquefied wax.

Thetreated fuel on removal from the bath has a hardly visible surface film of wax. It has been determined experimentally that a surface film of the same order of magnitude resulting from instantaneous clipping of the char in the same wax at the same temperature F.) is not sufficient to provide the heat energy necessary to raise the temperature of the charcoal to its ignition temperature Within a reasonable time, i. e. about 15 minutes. Similarly, impregnation periods greater than 20 seconds cause an undue amount of wax to be adsorbed, resulting in smokiness due to wax distillation during combustion from the capillaries and pores. The time period is critical in permitting controlled release of heat energy from the wax in a manner which ignites the whole mass of base fuel by the time the auxiliary fuel has itself been consumed. The temperature is critical, for at temperatures less than 165 F. impregnation proceeds far more slowly while undesirable surface coating formation is the prinicpal phenomenon. In general, the increase in weight of the impregnated fuel is from about5% to 15%.

The treated fuel may be ignited in any one of several convenient ways. The simplest means is by placing crushed paper on top of a quantity of fuel on a grate or similar receptacle, and igniting the paper. Ignition is rapid, and within 15 minutes the fuel is substantially completely burning, the entire amount of impregnated wax having been consumed. Another convenient manner, particularly adaptable to picnics or other occasions where relatively small amounts of fuel are required, is to package the treated fuel in a paper bag or box, or a fabric mesh bag which may or may not be wax-treated, and igniting the container. In all cases, the flame will spread evenly and quickly over the treated fuel, essentially without smoke if there is adequate draft, and will ignite the whole mass.

It is important to note that the fuel of the present invention can only be prepared from porous fuels by impregnation. Coating of non-porous fuels even by immersion in wax of the required temperature and characteristics, is not enough. Thus, two non-adsorptive carbonaceous fuels, namely, petroleum coke and fluid coke, a coke derived from coking petroleum residue by the fluid coking process, were treated in the manner described above. Both samples had been subject to high temperature prior processing and were non-adsorptive. After immersion, neither of these fuels would ignite or continue to burn after the wax coating had been consumed.

The process and product of the present invention may be subject to many modifications obvious to those skilled in the art. Thus with chars of high density, it may be desirable to-employ a second auxiliary fuel to increase still further the rate of heat energy released to the solid fuel to heat the latter to its ignition temperature within a prescribed time limit. Such auxiliary fuel may be an aliphatic, aromatic, naphthenic or oxygenated liquid bydrocarbon having a flash point of 100 F. minimum and a boiling range not exceeding 100 F. between the 5% and 95% points, and a final boiling point not exceeding 425 F.

In this embodiment, the solid fuel is immersed in the volatile liquid at ambient temperature for a period up to one second, whereby approximately 5% by weight of the liquid, based on solid fuel, is adsorbed. Thereafter, the fuel composition is immersed in the wax at a temperature above its melting point. This treatment provides a thin wax coating effectively sealing in the more volatile hydrocarbon. The weight loss of such a fuel at ambient temperature over a period of 30 days is negligible.

The wax may, if desired, contain in solution a waxsoluble dye. In this way, the fuel may be colored in any manner desired.

What is claimed is:

'1. The process of preparing a treated fuel which comprises impregnating charcoal with molten parafiin wax References Cited in the file of this patent FOREIGN PATENTS 477,770 Canada Oct. 16, 1951 OTHER REFERENCES The Chemistry and Technology of Waxes, Warth, Reinhold Pub. Corp, New York, 1947, pages 225-6.

Claims (1)

1. THE PROCESS OF PREPARING A TREATED FUEL WHICH COMPRISES IMPREGNATING CHARCOAL WITH MOLTEN PARAFFIN WAX FOR A PERIOD OF FROM ABOUT 5 TO ABOUT 20 SECONDS AT A TEMPERATURE NOT LESS THAN 165*F. AND RECOVERING A FUEL OF SUPERIOR IGNITION CHARACTERISTICS.