US3402032A - Fuel compositions - Google Patents

Description

United States Patent 3,402,032 FUEL COMPOSITIONS John W. Schick, Cherry Hill, N.J., assignor to Mobil Oil Corporation, a corporation of New York No Drawing. Continuation of application Ser. No.

471,720, July 13, 1965, which is a continuation-inpart of application Ser. No. 401,665, Oct. 5, 1964. This application June 20, 1967, Ser. No. 647,568

13 Claims. (Cl. 4417) ABSTRACT OF THE DISCLOSURE A process is provided for the manufacture of fuel compositions comprising specified proportions of petroleum coke, woodsawdust, charcoal, an oxidizing agent and a binder, comprising forming a mixture of petroleum coke, wood-sawdust and charcoal components, forming another mixture comprising an aqueous solution of the oxidizing agent and binder, combining these mixtures, forming from the combined mixture a fuel composition of desired shape, and drying the fuel composition thus formed at a temperature from about 200 F. to about 275 F. in an atmosphere having an absolute humidity value from about 0.12 to about 0.20 pound of water per pound of said atmosphere, to obtain a dehydrated fuel composition.

This invention is a continuation-in-part of my application Ser. No. 401,665, and now abandoned, filed Oct. 5, 1964, and a continuation of my application Ser. No. 471,720, filed July 13, 1965, now abandoned, and relates to fuel compositions and, more particularly, to artificial carbonaceous fuel compositions having improved burning properties and to the method for their preparation. Still more particularly, the invention relates to artificial carbonaceous fuel compositions, in the form of briquettes having improved burning properties, the method for their preparation, and having particular utility when employed for purposes of orchard heating.

Heretofore, a serious problem has been encountered in combating low-temperature and frost conditions, seasonally encountered in orchards and other outdoor vegetation and in crop areas, which cause destruction or heavy damage to fruit, branches, limbs and, in many instances, to vines and trees themselves. To offset these injurious effects of periodic low-temperature climatic conditions, it is essential that there be provided a source of heat and means for carrying such heat to the vines, trees and other vegetation. For this purpose, heat has heretofore been supplied by various means, ranging from conventional gas and fuel-oil burning frost-pots and return-stack heaters to smudging and the burning of scrap rubber, and in which heat is carried to the vegetation by convection currents, or, in more sophisticated installations, by wind-machines designed to induce such currents. In this respect, however, the use of such devices has resulted in the accompanying dissipation of large quantities of smoke, causing the deposition of soot or smudge upon the fruit or vegetation. Furthermore, the presence of an open flame in close proximity to the fruit, vines, trees or other vegetation may also result in their damage or even in their destruction. Also, prior to the present invention, the burning of artificial solid carbonaceous fuels in the form of small lumps or briquettes in specially designed heaters, has been resorted to; however, in these instances, a smokeless type of fuel briquette is not available. Furthermore, apart from the undesirable deposition of soot resulting from the burning of the briquette, the presence of an open flame is still another factor which heretofore has rendered the use of carbonaceous briquettes, as a source of heat, unattractive for the aforementioned intended purpose.

3,402,032 Patented Sept. 17, 1968 The ability to employ a substantially smokeless fuel composition, for example, in the form of a briquette,

which is capable of burning without the presence of any substantial flame, would, therefore, be highly desirable. The use of equipment such as the aforementioned frostpots, return-stack heaters, wind-machines, etc. would be completely eliminated, with its attendant saving in cost. In addition, the ability of the fuel composition to burn without the presence of a flame would permit placing it in close proximity to the trees, vines or other forms of vegetation, and would thus avoid expensive waste of heat values, which is presently encountered when the heat source must be placed at a considerable distance from the desired point of application.

Prior to the present invention, charcoal briquettes or lumps for heating purposes, have generally been fabricated from mixtures containing small amounts of charcoal and minor amounts of filler materials such as sawdust, wood shavings, or excelsior, and various forms of binding agents. Such mixtures are usually compressed under relatively high pressure into the briquette or lump form, and are subsequently coated by immersion or spraying with a water-proofing agent, such as varnish, paraffin, or a resinous or plastic material. Various formulary modifications have also been suggested, including improvements relating to the filler binder and water-proofing components. In all such formulations, it is found, however, that certain highly undesirable disadvantages are inevitably present. Of particular significance is the fact that the conventional briquette or lump-form composition cannot be burned without the release of smoke or the presence of an open flame, as hereinbefore described. Apart from these disadvantages, the ability of the briquette to release its heat at a controlled rate, is highly desirable from both a practical and economic standpoint. In this respect, the conventional form of briquette is also deficient.

In application Ser. No. 401,665, and now abandoned, filed Oct. 5, 1964, there were disclosed new and improved solid fuel compositions, preferably in the form of briquettes, which are manufactured, in general, by first forming a mixture comprising petroleumcoke, wood-sawdust and charcoal components; forming another mixture comprising an aqueous solution of an oxidizing agent and a binder; combining these mixtures to form a slurry; and then subjecting this slurry to an extrusion operation to obtain a briquette of the desired configuration. Subsequently, the briquette thus produced is then passed into a heater or other device, in Which Water is removed at elevated temperatures.

In carrying out the aforementioned water removal or drying operation, it has been found that, in some instances, the water-soluble oxidizing agent tends to leach out and to migrate toward the surface of the molded fuel composition. This results in the formation of relatively high concentrations of oxidizing agent at, or slightly below, the surface of the fuel composition. Upon being ignited, the fuel composition is found to flare explosively or to exhibit a high degree of flaming, thereby causing the fuel to burn too slowly or not at all, and in turn reducing or entirely eliminating the efficacy of the fuel composition as a source of heat for protecting 'vegetation against frost damage. The present invention, therefore, is concerned with, and has as one of its objects, the carrying out of the aforementioned drying operation in such manner that the migration of the oxidizing agent toward the surface of the solid fuel composition is avoided, thereby eliminating the above-described disadvantages and resulting in the formation of a dehydrated solid fuel composition, which will not flare explosively, or flame excessively upon ignition, and which can burn at an effective, controlled rate to satisfy its intended purpose.

In accordance with the present invention, these and other objects are attained, as more fully hereinafter described, by conducting the aforementioned drying operation under atmospheric conditions of controlled humidity, and, in this manner, it has been found that the drying of the solid fuel composition can be made to occur from the inside to the surface thereof, wherein water vapor alone migrates to the surface, leaving behind the oxidizing agent dispersed within the fuel composition. Upon ignition, the solid fuel composition, having been dried under these conditions is readily ignitable and continues to sustain combustion over a relatively long period, without any explosive, flaring or flaming effects.

More particularly, in accordance with the present invention, the aforementioned drying operation of the abovedescribed molded solid carbonaceous fuel composition is carried out under critical temperature conditions from about 200 F. to about 275 F. (preferably at a temperature from about 255 F. to about 250 F.), and in an atmosphere having an absolute humidity value from about 0.12 to about 0.20 pound of water per pound of said atmosphere, to obtain a dehydrated, substantially smokeless and fiameless fuel composition, with the above-described attendant advantages. The criticality of carrying out the drying operation under the aforementioned temperature and controlled atmospheric humidity conditions, is demonstrated by the fact that since, for example, completely saturated air at 6070 F., exhibits a relative humidity value of only about 0.01 to about 0.03, the solid fuel composition, when dried in this atmosphere at a temperature within the aforementioned range of from about 200 F. to about 275 F., causes drying to occur from the surface of the fuel inwards, i.e., liquid water will migrate to the surface in order to maintain the fuel composition and the surrounding atmosphere in equilibrium. This liquid water movement, will, therefore, carry the oxidizing agent toward the surface of the fuel composition, with the aforementioned resulting disadvantages. However, by employing an atmosphere, e.g., air, having an absolute humidity value from about 0.12 to about 0.20 pound of water per pound of this atmosphere, at the aforementioned temperature range of from about 200 F. to about 275 F., the drying of the solid fuel composition is able to occur from the inside to the surface thereof, wherein water vapor alone migrates, leaving behind the oxidizing agent. In this manner, an effectively improved solid fuel composition, is attained.

With respect to the aforementioned drying temperature range of from about 200 F. to about 275 F., it is found that employing a drying temperature below about 200 F. the drying time required is of such extremely long duration as to result in an uneconomic and impractical operation. On the other hand, employing a drying temperature above about 275 F., causes autogenous ignition of the fuel composition to occur. With respect to the aforementioned absolute humidity value of the drying atmosphere employed, it is found, as hereinbefore indicated, that if the absolute humidity value is below about 0.12 pound of water per pound of said atmosphere, migration of the oxidizing agent to the fuel surface will occur. n the other hand, it is found that if the absolute humidity value is above about 0.20 pound of water per pound of the drying atmosphere, the quantity of water present is such that it will approximate the eifect of live steam, during the drying operation, making dehydration impossible.

Insofar as the individual components of the fuel compositions of the present invention are concerned, the aforementioned petroleum coke component is of particular importance. Petroleum coke, being a refractory carbonaceous residue material, has not heretofore been considered as having any significant fuel value, from a practical commercial standpoint, because of its characteristic lack of being easily ignitable and its inability to readily support combustion. Thus, petroleum coke, which is generally commercially obtained in the form of either a delayed coke or fluid coke, possesses a low volatility content and is ignitable only at temperatures as high as from about 2500 F. to about 2700 F. Delayed coke, varying in physical properties from finely divided particles to relatively coarser and larger particles, is more volatile and less carbonaceous than fluid coke, and is ignitable at a somewhat lower temperature within the aforementioned range, than fluid coke. In this respect, it is found that if petroleum coke can be successfully ignited to a temperature where it can support combustion, it can burn, in a state of glow, without the emission of smoke or the presence of an open flame, and at a controlled rate, making possible the realization of the previously discussed advantages.

In order to attain the aforementioned relatively high temperatures required for initially igniting the petroleum coke and for subsequent selfburning sustained combustion thereof, the solid fuel compositions of the present invention are also comprised of minor proportions of charcoal and wood-sawdust, in combination, as a filler material. In this respect, ignition of the charcoal component results in the combustion thereof at a sufficiently high tem perature which is effective for the subsequent ignition and support of combustion of the petroleum coke. The presence of the wood-sawdust component in the filler material makes possible a combustion mechanism in which the sawdust, being the most easily combustible component present, is most readily ignitable, gives off sufficient heat upon being combusted to ignite the charcoal component, and the latter, upon being ignited and combusted, in turn gives off heat at a relatively increased temperature, which is sufficient for the purpose of igniting and initiating sustained combustion of the petroleum coke.

In order to initiate the combustion of the wood-sawdust component in the above-described aforementioned filler material, the aforementioned oxidizing agent, capable of supporting combustion, is incorporated as a component of the solid fuel composition. The concentration of this oxidizing agent in the solid fuel composition above the minimum level required to support combustion of the petroleum coke, can be varied to any desired burning rate. Various types of oxidizing agents may be employed for this purpose, and particularly preferred are the nitrates, perchlorates, peroxides and permanganates, although any type of oxidizing agent which is capable of supporting combustion can be successfully employed for this purpose. It will be apparent, of course, that in a given instance each oxidizing agent would be employed in different amounts in order to obtain a desired burning rate for the fuel composition. In essence, therefore, this ability of being able to effect ultimate combustion of the petroleum coke in a sustained manner and at a controllable burning rate, makes possible the production of a solid fuel composition which can burn without the presence of smoke or an open flame, and with all the obvious attendant advantages, described above.

For purposes of consolidating and obtaining a shaped solid fuel, for example in the form of a briquette or other configuration, a minor proportion of a binder is included in the improved fuel compositions of the present invention. For this purpose, any compatible combustible binder, either natural or synthetic, can be employed. These may include resinous materials, plastics, paraflins, shellac and combustion-supporting adhesives. Particularly preferred are binders comprising a soluble starch. From a practical standpoint, in instances where the fuel composition is to be employed for outdoor heating purposes, the presence of a minor proportion of a water-proofing agent is highly desirable. For this purpose, any compatible combustible water-proofing agent may be incorporated in the fuel composition. These may include water insoluble but dispersible resins and polymers such as polyethylene, and relatively not volatile, viscous, combustible natural or synthetic oils. Particularly preferred are water-proofing agentscomprising wax emulsions.

As previously indicated, the fuel compositions of the present invention comprise a major proportion of petroleum coke and minor proportions of wood-sawdust, charcoal, oxidizing agent and binder. From a practical standpoint, these fuel compositions comprise, by weight, from about 50 to about 90 percent, and, preferably from about 60 to about 80 percent petroleum coke; from about 3 to about 20 percent, and preferably from about 5 to about percent wood-sawdust; from about 4 to about 40 percent, and preferably from about 7 to about percent charcoal; from about 2 to about 15 percent, and preferably, from about 5 to about 10 percent oxidizing agent; and from about 1 to about 10 percent, and, preferably, from about 3 to about 5 percent binder. In instances where a water-proofing agent is to be employed, the latter is present in an amount from about 0.5 to about 8 percent, and, preferably, from about 1 to about 2 percent, by weight.

In one of its preferred embodiments, in order to facilitate the ignition of the above-described novel fuel compositions of the present invention, an igniting composition may be applied to at least a portion of the fuel composition. This igniting composition is comprised of the same components as are now present in the fuel composition itself, except for the absence of the petroleum coke component. Ignition of this layer causes a relatively high degree of heat to be transmitted to the basic fuel composition itself, for more rapid and complete ignition of the latter. In its preferred form, this ignition composition comprises, by weight, from about 41.7 to about 47 percent sawdust; from about 41.5 to about 47 percent charcoal; from about 4 to about 10 percent oxidizing agent, and from about 2 to about 5 percent binder. In instances where a water-proofing agent is to be employed, the latter is present in an amount from about 0.4 to about 2 percent, by Weight.

The preparation of the novel solid fuel compositions of the present invention is, in general, carried out by forming a mixture comprising the petroleum coke, wood-sawdust and charcoal components; forming another mixture comprising an aqueous solution of the oxidizing agent and binder (the water-proofing agent may also be included in this mixture, if its presence is desired); combining these mixtures; and forming from these combined mixtures; the fuel composition of the desired shape. In a preferred, and more specific method of manufacture, the petroleum coke and charcoal components, in accordance with the above-described proportional requirements, are crushed or pulverized, and, thereafter, the wood-sawdust component is added. These three components, in their required proportions, are then mixed in the dry state. A separate mixture of an aqueous solution of the oxidizing agent and binder (and the water-proofing agent, if its use is indicated) is formed in accordance with the aforementioned required proportions. The thus-obtained dry and wet mixes are then combined, molded to the desired shape and dried under the aforementioned atmospheric conditions, and the solid fuel composition is then ready for use.

In its preferred form, when the solid fuel composition is to be employed in the form of a briquette, the dry and wet mixes are combined in the form of a slurry, and this slurry is then subjected to an extrusion operation. In this modification, the slurry is preferably fed into a pug mill and forced through a die of such contour as to obtain a briquette having the desired dimensions. The briquette thus produced is then passed into a heater or other device, in which water is removed at temperatures from about 160 F. to about 250 F. In another form the slurry may be pressed in a mold to the desired shape or form and then dried. Also, if so desired, the solid fuel composition may be immersed in, or sprayed with, a water-proofing agent, if such agent was not originally present as a component of the aforementioned wet mix.

If the presence of the aforementioned igniting composition is desired, a thin layer of this composition is added to at least a portion of the surface of the formed solid fuel composition, When the fuel composition is to be obtained in the form of a briquette, this layer, is preferably applied by spraying a separate mixture of charcoal, oxidizing agent and binder components (and also the waterproofing agent, if so desired), and, simultaneously, spraying the sawdust component through a separate nozzle (to avoid nozzle plugging) over the surface of the solid fuel, or briquette composition, to form the igniting composition layer, in situ. In this instance, also, the Waterproofing agent may be applied over the entire surface of the igniting layer and the basic fuel composition itself, if so desired, and if not previously incorporated either in the igniting layer or the basic fuel composition, or both. Also, the entire mixture of charcoal, sawdust, oxidizer, binder and water-proofing agent can be extruded directly onto the surface of the briquette. A more detailed description of the method for preparing and molding the undehydrated fuel composition of the present invention, is described in my aforementioned application Ser. No. 401,665, and the disclosure thereof is incorporated herein by reference.

The outstanding feature of the novel solid smokeless and fiameless fuel compositions of the present invention resides in the phenomenon that, unlike the combustion of conventional charcoal briquettes or pellets, the heat realized is in the form of radiant, infra-red, heat emanations. This form of heat is transmitted by radiation directly to the fruit, limbs, trunks or other forms of vegetation, with minimum loss to the atmosphere. In contrast, it will be noted that conventional grove-heating systems, employing other types of fuel, operate, principally, by heating the air and carrying air, so heated, by convection currents to the desired point of application. In the latter instance, much of the gaseous heat tends to escape without being carried to the vegetation. In actual practice, when employed for outdoor heating, the solid fuel composition, preferably in the form of a briquette, being resistant to weather, can be stored on the ground, or, for example, in the crotch of a tree, for use when frost appears to be imminent. When temperature conditions are such as to indicate the use of these compositions, the briquette may be placed on the ground in the vicinity of the vegetation, or hung from tree limbs, in any convenient manner, and easily ignited by the flame of a torch or other kindling means. In essence, therefore, the present invention provides a method for protecting vegetation against frost damage by combust-ing a smokeless and flameless solid carbonaceous material, in open atmosphere, which is positioned substantially below the top of the vegetation to be protected and within the area bounded by terminal points of the vegetation, in which radiant heat emitted at the surface of the solid material is absorbed by elements of the vegetation to provide a degree of protection to all elements thereof, and efficiency of fuel utilization both in excess of that obtainable by convection heating, characteristic of flame combustion, and of combustion occurring within a confined areas such as a metallic stove. In its more specific form of application, this method provides placing the solid carbonaceous material, e. g., in the form of a briquette, at a vertical position substantially below the top of a tree to be protected and at a horizontal position within the area bounded by the ends of limbs, to provide protection to all elements of the tree, as described above. In this respect, it has been found that a briquette comprising approximately, by weight, 69 percent petroleum coke, 10 percent Wood-sawdust, 10 percent charcoal, 5 percent sodium nitrate, 5 percent starch and 1 percent wax emulsion, and covered with an igniting composition comprising, approximately, by weight, 44 percent wood-sawdust, 44 percent charcoal, 8.8 percent sodium nitrate, 2.3 percent starch and 0.9 percent wax emulsion, and measuring 6" x 6 x 9", is capable of releasing approximately 10,000 Btu. per hour. With a depth of 6", the briquette can burn for a period of 4 hours, i.e., at the rate of 1 /2" per hour. Briquettes prepared in this manner, and dried under the above-described critical temperature and atmospheric humidity conditions, will satisfactorily perform their function without flaring explosively, or flaming excessively, upon ignition, and will continue to burn at an effective controlled rate without the presence of any substantial smoke or flame.

The following examples and comparative data, as shown in the accompanying table, will serve to exemplify the above-described improved characteristics of the novel fuel compositions of the present invention, in the preferred form of briquettes, prepared and subjected to drying treatment under the aforementioned critical temperature and humidity conditions. The briquettes employed in the comparative examples, each contained, by weight, 43% petroleum coke, 12.5% of a 50:50 charcoalzwood-sawdust mixture, 3% starch, 9.5% sodium nitrate and 32% water, and were prepared in accordance with the previously described procedure, viz., by first forming a mixture comprising the petroleum coke, woodsawdust and charcoal components; forming another mixture comprising Water, sodium nitrate and starch components, and then combining these mixtures and subjecting the thus-combined mixture to an extrusion molding operation to obtain an undried briquette of the desired shape. The thus-shaped undried briquette compositions were then subjected to a series of investigations (as shown by the examples of the following table) to determine the present atmospheric humidity value levels, at various temperatures, required to produce an acceptable fuel composition, exhibiting no substantial flaring or flaming upon ignition.

troleum coke, wood-sawdust and charcoal components; forming another mixture comprising an aqueous solution of said oxidizing agent and binder; combining said mixtures; forming from said combined mixture a fuel composition of desired shape; and drying the fuel composition thus formed at a temperature from about 200 F. to about 275 F. in at atmosphere having an absolute humidity value from about 0.12 to about 0.20 pound of water per pound of said atmosphere, to obtain a dehydrated substantially smokeless and flameless fuel composition.

2. A method for manufacturing a fuel composition, comprising, by weight, from about 50 to about 90 percent petroleum coke, from about 3 to about 20 percent woodsawdust, from about 4 to about percent charcoal, from about 2 to about 15 percent of an oxidizing agent capable of supporting combustion, and from about 1 to about 10 percent of a binder, which comprises: forming a mixture comprising said petroleum coke, wood-sawdust and charcoal components; forming another mixture comprising an aqueous solution of said oxidizing agent and binder; combining said mixture; forming from said combined mixture a fuel composition of desired shape; and drying the fuel composition thus formed at a temperature from about 200 F. to about 275 F. in an atmosphere having an absolute humidity value from about 0.12 to about 0.20 pound of water per pound of said atmosphere, to obtain a dehydrated substantially smokeless and fiarneless fuel composition.

3. The method of claim 2 wherein the drying of said fuel composition is carried out at a temperature from TABLE.CONTROLLED HUMIDITY DRYING OF FUEL BRIQUETTES Air Absolute Drying Example Temp., Velocity, Hunidity, Time, Quality of Observations F. Ftjsec. Lb. 1120/ Hours Product Lb. Air

9 n 333 3:3 318; it .litfififlittlliiiiii fittiii it ionlrmilmnsumedmhm- 220 0.2 0. 14 29 Acceptable Only flamed on top ignition surface 1370% consumed in 4 hours. 220 0. 2 0. 10 26 Unacceptable. Flamed 6-8. 235 0. 2 0. 12 20 250 0.2 0. 20 21 No flame-7075% consumed in 4 hours. 250 10 0. 20 9-10 250 5 0. 02 9-10 Flamed 1218-50% consumed in 4 hours. 250 5 0.15 10 No flame. 250 5 0.10 10 Flamed 68". 532 g 8: do :}No fiame70-72% consumed in 4 hours.

From the foregoing examples, it will be noted that by maintaining an absolute humidity value within the aforementioned range of from about 0.12 to about 0.20 pound of water per pound of drying atmosphere, and Within the aforementioned drying temperature range of from about 200 F. to about 275 F., a satisfactory product is obtained which will exhibit no substantial flaring or flaming upon ignition, and which will continue to burn without any substantial smoking or flaming. In this respect, it was further found that if at least about of the water-content of the fuel composition was removed with the humidified air, the remainder of the water could then be removed with dry air. Compositions of poor quality resulted when less than about 50% of the water content was removed with humidified air.

While preferred embodiments of the novel smokeless and flameless fuel compositions of the present invention, and the method for their preparation, have been described for the purpose of illustration, it will be understood that various modifications and adaptations thereof, which will be obvious to those skilled in the art, may be made without departing from the spirit of the invention.

I claim:

1. A method for manufacturing a fuel composition comprising a major proportion of petroleum coke and minor proportions of wood-sawdust, charcoal, and oxidizing agent capable of supporting combustion and a binder, which comprises: forming a mixture comprising said peabout 225 F. to about 250 F.

4. A method for manufacturing a fuel composition, comprising, by weight, from about 60 to about percent petroleum coke, from about 5 to about 15 percent wood-sawdust, from about 7 to about 20 percent charcoal, from about 5 to about 10 percent of an oxidizing agent capable of supporting combustion, and from about 3 to about 5 percent of a binder, which comprises; forming a mixture comprising said petroleum coke, Wood-sawdust and charcoal components; forming another mixture comprising an aqueous solution of said oxidizing agent and binder; combining said mixtures; forming from said combined mixture a fuel composition of desired shape; and drying the fuel composition thus formed at a temperature from about 200 F. to about 275 F. in an atmosphere having an absolute humidity value from about 0.12 to about 020 pound of water per pound of said atmosphere, to obtain a dehydrated substantially smokeless and flameless fuel composition.

5. A method for manufacturing a fuel composition, comprising, by weight, from about 60 to about 80 percent petroleum coke, from about 5 to about 15 percent woodsawdust, from about 7 to about 20 percent charcoal, from about 5 to about 10 percent sodium nitrate, and from about 3 to about 5 percent starch, which comprises: forming a mixture comprising said petroleum coke, wood-sawdust and charcoal components; forming another mixture comprising an aqueous solution of said sodium nitrate and starch; combining said mixtures; forming from said combined mixture a fuel composition of desired shape; and drying the fuel composition thus formed at a temperature from about 200 F. to about 275 F. in an atmosphere having an absolute humidity value from about 0.12 to about 0.20 pound of water per pound of said atmosphere, to obtain a dehydrated substantially smokeless and flameless fuel composition.

6. The fuel composition prepared by the method of claim 1.

7. The fuel composition prepared by the method of claim 5.

8. A method in accordance with claim 2 wherein an igniting composition is applied to at least a portion of the formed fuel composition, said igniting composition comprising, by weight, from about 41.5 to about 47 percent wood-sawdust, from about 4 to about 10 percent of an oxidizing agent capable of supporting combustion, and from about 2 to about 5 percent of a binder.

9. A method in accordance with claim 4 wherein an igniting composition is applied to at least a portion of the formed fuel composition, said igniting composition comprising, by weight, from about 41.5 to about 47 percent wood-sawdust, from about 4 to about 10 percent of an oxidizing agent capable of supporting combustion, and from about 2 to about 5 percent of a binder.

10. A method in accordance with claim 5 wherein an igniting composition is applied to at least a portion of the formed fuel composition, said igniting composition comprising, by weight, from about 41.5 to about 47 percent wood-sawdust, from about 4 to about 10 percent of an oxidizing agent capable of supporting combustion, and from about 2 to about 5 percent of a binder.

11. The fuel composition prepared by the method of claim 8.

12. The fuel composition prepared by the method of claim 9.

13. The fuel composition prepared by the method of claim 10.

References Cited UNITED STATES PATENTS 401,365 4/ 1889 Murray et al 446 435,076 8/ 1890 Pagenstecher 4417 1,050,535 1 1913 Hartung 44-20 1,990,948 2/1935 Loghry 4420 2,212,157 8/ 1940 Fernholtz 4438 2,531,828 11/1950 Schultz 4441 3,068,080 12/ 1962 Ronzio 4417 FOREIGN PATENTS 494,770 11/ 1938 Great Britain.

DANIEL E. WYMAN, Primary Examiner.

C. F. DEES, Assistant Examiner.

U.$. DEPARTMENT OF COMMERCE PATENT OFFICE Washington, D.C. 20231 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,402,032 September 17, 1968 John W. Schick It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3, line 19, "255 F." should read 225 F. Column 6, line 56, "areas" should read area Column 7, line 73, "and" should read an Signed and sealed this 3rd day of February 1970.

(SEAL) Attest:

Edward M. Fletcher, Jr. WILLIAM E. SCHUYLER, JR- Attesting Officer Commissioner of Patents