[0001]    This application claims priority from U.S. provisional patent application serial No. 60/249,628, filed on Nov. 18, 2000. 
     
    
     
       FIELD OF THE INVENTION  
         [0002]    This invention relates to fuels used in explosive, pyrotechnic, gas-generating and propellant compositions. More specifically, this invention finds particular, but not exclusive, utility in compositions intended to replace black powder in all its applications.  
         BACKGROUND OF THE INVENTION  
         [0003]    Explosive compositions must comprise a fuel and a source of oxygen. Oxygen is frequently supplied by nitrates, chlorates, permanganates, peroxides and other oxidizers, known in the art. The fuel should comprise materials that can theoretically be oxidized completely and rapidly. Ideally, there should be very little residue remaining after the reaction takes place, with as much of the original material as possible being converted to heat energy and gases.  
           [0004]    It is known in the art that the characteristics and performance of an explosive composition can be significantly altered by the use of various oxidizers, as well as various amounts of the oxidizer component, while the fuel component remains unchanged, and of course, vice-versa. The primary examples of these types of compositions are black powder and Pyrodex® powder. When black powder is burned, approximately  56 % of the total weight remains as solid material. As is known to persons who use black powder in firearms, this residue causes fouling of the barrel and repeated, unpleasant cleaning of the firearm. Many times the barrel must be swabbed out between shots. The presence of sulfur in black powder results in combustion products which, when combined with atmospheric moisture, can cause corrosion of the barrel. While Pyrodex® powder causes less fouling, it not only contains sulfur, but also contains potassium perchlorate, which results in the formation of soluble chloride salts. Such salts are also corrosive to the barrel.  
           [0005]    Historically, sucrose is known as a component of pyrotechnic compositions. Attempts have been made to produce gunpowder from sucrose and potassium chlorate, with unpredictable and disastrous results. Timmerman discloses, in U.S. Pat. No. 3,862,866, the use of sucrose and potassium chlorate in gas generating compositions. The sucrose is used in an unmodified and unreacted form. Other explosive compositions have been formulated which exhibit improved safety, performance, and other improved characteristics. Some of these are described in the following U.S. patents, the disclosures of which are incorporated herein by reference:  
           [0006]    U.S. Pat. No. 4,407,676—Kurtz—Gunpowder substituted composition and Method  
           [0007]    U.S. Pat. No. 4,728,376—Kurtz—Explosive Composition and Method  
           [0008]    U.S. Pat. No. 4,881,993—Furbringer et al.—Explosive and Propellant Composition and method of Preparation  
           [0009]    U.S. Pat. No. 4,964,429—Beyeler et al.—Preparation of Explosives Containing Degradation Products of Ascorbic or Isoascorbic acid  
           [0010]    U.S. Pat. No. 4,992,496—Wehrli—Fuel and Explosive Composition and Method of Making Same  
           [0011]    U.S. Pat. No. 5,465,664—Fey—Fuel and Explosive Composition with Ferric or Cupric Ion and Reducing Sugars  
           [0012]    With the exception of U.S. Pat. No. 5,465,664—Fey, the explosive compositions disclosed in these patents consists primarily of an organic acid fuel, usually ascorbic or erythorbic acid, and an inorganic nitrate oxidizers usually potassium nitrate. While these compositions exhibit varying degrees of performance, they commonly exhibit reduced fouling and non-corrosive properties when use in firearms, along with greatly reduced residue. A couple of the major drawbacks, common to all the compositions disclosed in the above referenced U.S. patents, are the cost of raw materials and the instability of the raw materials market. In addition, many of these compositions exhibit unacceptable levels of hygroscopicity.  
         SUMMARY OF THE INVENTION  
         [0013]    It an object of the present invention to produce a fuel composition for use in explosive, gas-generating, and pyrotechnic compositions. Such fuel exhibits improved performance, excellent binding and cohesive properties and greatly reduced cost and stability of the raw materials market.  
           [0014]    It is a further object of the present invention to produce a fuel composition well suited for use as a modifier in explosive, pyrotechnic, and propellant compositions.  
           [0015]    It is a still further object of the present invention to produce an explosive composition comprising an improved fuel composition and an oxidizing agent.  
           [0016]    It is a further object of the present invention to use such improved fuel composition to form an explosive composition which, when utilized as a gunpowder evidences improved performance, including improved burn characteristics, with less residue and producing equal or greater velocities at pressures comparable to those produced by black powder and other existing “black powder substitutes”.  
           [0017]    It is a further object of the present invention to use caramel color bodies as fuels for explosive compositions.  
           [0018]    Toward the fulfillment of these and other objects and advantages, a fuel composition is disclosed that comprises insoluble caramel color bodies produced by the thermal degradation of carbohydrates. The fuel composition may be prepared using a carbohydrate such as a sugar and using an acid catalyst, such as using oxalic acid or citric acid. The fuel composition may be prepared by dissolving the carbohydrate in water to form a solution, and heating the solution over time so that a portion of the carbohydrate is converted to an insoluble polymer. The solution is preferably heated until at least approximately  40 % by weight of the carbohydrate is converted to an insoluble polymer and is more preferably heated until at least approximately 50% by weight of the carbohydrate is converted to an insoluble polymer. An explosive composition may be prepared by combining an oxidizer with caramel color bodies. The caramel color bodies are preferably non-hygroscopic, have a neutral pH, and have a high molecular weight.  
         DESCRIPTION OF THE PREFERRED EMBODIMENT  
         [0019]    Historically, it is known in the energetic materials trade that such carbohydrate materials as sugars and starch can be used as fuels in propellant and explosive mixtures with suitable oxidizers, to produce acceptable energetic materials—although usually suffering from water absorption, storage, sensitivity and stability problems. There is no known record of the use of caramel or caramel color bodies as a fuel for energetic materials. This is thought to be a result of the general observation that the caramelization process of sugars and starches is a severe modification, degradation and polymerization process, which would not provide fuel performance approaching that found for the sugars or starches. I have discovered that caramel, particularly caramel color bodies, is a superior fuel for energetic materials.  
           [0020]    Caramel is a food additive or ingredient (see CFR 21, Part 182—Substances Generally Retarded as Safe—Sub-part B—Multiple Purpose GRAS Food Substances, paragraph 182-1235) ordinarily prepared by the thermal treatment of sugar, and generally utilized broadly for uses such as food colorant, flavoring, general purpose (e.g. cosmetics, industrial products) coloring agent, and binder. It is widely thought in the caramel manufacture industry that the material is a carbohydrate polymer derived from sugar, with greater color intensity related to higher degree of polymerization, and lower free sugar content. Caramel is sometimes referred to as “burnt sugar”, and many caramel materials are classified chemically under CAS # 8028-89-5 (see Book 4 of the TSCA List), while the polymeric nature of caramel color is little known, it is believed to contain, variably, compounds with molecular weights ranging from under approximately 1,000, to greater than approximately 30,000. For food uses, the presence of caramel color bodies, insoluble polymeric components of caramel color, is typically considered undesirable. Accordingly, the raw materials and manufacturing techniques are typically geared toward minimizing the presence of these insoluble polymeric materials. In contrast, according to the present invention, it is desirable to maximize the presence of caramel color bodies, these insoluble, polymeric components of caramel color.  
           [0021]    Caramel color is primarily used in food and beverage applications. It is typically prepared by the controlled heat treatment of specified food grade carbohydrates—principally high dextrose corn syrup—using specified food grade catalysts including citric, acetic, and phosphoric acids; calcium and sodium hydroxides; ammonia; sulfites; and specified salts. In the caramel industry, it is desirable that the caramel color bodies remain colloidal in size and therefore dispersible when used in various food related applications. Great care is taken in the food industry to keep from breaking the colloidal structure and thereby precipitating the caramel color bodies as insoluble and non-dispersible solids. Commercially manufactured caramel color is available in a wide range of colors and tinctorial powers and can be obtained in either liquid or dried powder forms. The commonly found impurities are calcium, sodium, potassium, phosphorus, various sulfites, and unreacted carbohydrates. Frequently present are very small amounts of light organic acids, ketones, aldehydes, alcohols, furans, furfurals, phenols, and various other compounds. Upon combustion, the inorganic impurities typically yield increased ash, which contributes to fouling and residue when these fuels are utilized in gunpowder applications. For use in gunpowder applications it is preferred that the caramel color bodies be isolated and purged of impurities which might exist as a result of manufacturing. Although further processing is typically preferred, food grade caramel color can be utilized as fuels in blasting agents and other types of explosive or pyrotechnic compositions, where fewer adverse effects are caused by impurities.  
           [0022]    The present invention relates to the use of isolated caramel color bodies, as described herein, as one fuel component (not necessarily to only fuel component) in explosive, pyrotechnic, and gas-generating compositions. Many methods of manufacturing, isolation, purification, and product formulation are known in various arts. The present invention relates to the novel use of isolated and purified caramel color bodies. These caramel color bodies can be obtained from commercially available caramel color or can be manufactured specifically for the purposes described herein, using non-food-grade catalysts. In fact, it is preferred to manufacture these bodies specifically for these purposes, because many properties that are desirable for use in connection with the present invention are undesirable for food grade applications, and vice versa.  
           [0023]    The new fuel of the present invention is the coloring material generally called caramel color bodies, produced by controlled thermal treatment of mono- or di-saccharide sugars such as fructose, glucose, lactose and sucrose. I have discovered that commercial caramel colors (such as DD. Williamson and Co. Caramel Color Nos. 604 and Caramel Color No. 624—representing a wide range of caramelization) unexpectedly serve as superior energetic material fuels in appropriately compounded mixtures with oxidizer materials. While my experiments have shown that virtually all grades of caramel color bodies will serve as such fuels for energetic materials, I have further discovered that caramel color bodies with lower mono- or disaccharide residual content tend to provide a better balance of handling, storage, compounding and propellant properties than do less severely treated caramels—having higher glucose or sugar content. Accordingly, the higher molecular weight caramel color bodies find particular use as a fuel component used in gunpowder or black powder substitute compositions of the present invention. As stated above, these caramel color bodies are insoluble, non-hygroscopic, and easily obtained. Isolation and purification of the preferred caramel color bodies can be accomplished by precipitation, ultrafiltration and various other methods well known in the art. Importantly, though my discovery includes use of all caramel color bodies or additive materials as fuel for energetic materials.  
           [0024]    The fuel of the present invention is essentially precipitated or coagulated (the colloid has been broken solid caramel color bodies. It is non-dispersible/insoluble in water (and in most solvents) and is purified of soluble, low molecular weight organics, residual sugars, and inorganic alkali and metal salts typically found in food grade commercial caramel color materials.  
           [0025]    I have found in my own experiments that by carefully subjecting sugar to a time-temperature treatment, with or without certain recognized caramelizing additives, I am able to progressively caramelize the sugar through the various stages of caramelization typically found in commercial caramel products (most of which are water soluble), with increasing weight loss of the sugar. Weight loss of the sugar varies depending on the time-temperature schedule utilized, but typically ranges from 4-5% for a light brown caramel, up to as high as 15-34% for a dark brown caramel. By continuing the controlled heating, I am able to convert the caramel to a viscous polymer melt, which, on cooling, is found to be relatively insoluble in water, and which can be ground in a mortar to fine powder. Increased degrees of polymerization can be achieved by increasing the time-temperature treatment. The resultant polymer caramel fuel powder was found to be insoluble in water, alcohol, acetone, and mineral spirits. The fine polymer caramel powder was mixed with potassium nitrate in a ratio of approximately 2:1, and was then granulated into a substitute black powder. When loaded into a black powder rifle, this substitute black powder produced projectile velocities equivalent or superior to black powder for an equivalent load, with improved and safer barrel pressure-time curve, and with virtually no residue in the gun barrel.  
           [0026]    The present invention involves a thermal catalytic condensation and dehydration reaction of sugars, resulting in a precipitated, non-crystalline, polymeric solid material. The product of the reaction is crushed, ground, washed, filtered and pressed to remove a small quantity of organic intermediate compounds (which are recycled to the reactor). Maximum process temperatures are preferably less than approximately 360° F., and maximum process pressures preferably approximately 15 psig. In order to manufacture fuel according to the present invention, I first prepare conventional caramel color bodies using food grade reactant sugars, with or without catalysts, and typical time-temperature cooking profiles, as is done in the food industry. However, the cooking at reaction temperature is continued for an extended period of time in order to more completely caramelize unreacted sugar, and then to thermally “break” the colloid and coagulate the precipitated caramel color bodies into filterable particulate solids. This is all accomplished at temperatures in the range of from approximately 105° C. to a maximum of approximately 180° C. The cooking period is extended until approximately 30% to approximately 60% of the caramel color colloid formed is precipitated. Then the mother liquor is diluted with water and filtered. The desired product filter cake is washed and pressed to purge residual colloidal caramel color bodies of soluble light organic compounds typically found in commercial caramel color, residual soluble catalyst, and any soluble inorganic compounds that might be present. The washed filter cake is dried and ground as the desired precipitated caramel color bodies of the solid fuel product of the present invention. The filtrate and wash liquor may be recycled to the next batch. Volatile effluents consist primarily of water vapor, with small amounts of CO 2 , light organic acids, ketones, aldehydes and esters. Volatiles will be condensed and treated to neutralize the organic constituents. Small amounts of spent catalyst in water solution will be purged periodically and appropriately treated. I believe that precipitated caramel color bodies prepared in this manner contain only carbon, hydrogen and oxygen; present as purified high molecular weight precipitated caramel color bodies. It is of course understood that caramel color bodies prepared in this manner may contain matter other than carbon, hydrogen, and oxygen.  
           [0027]    The resultant fuel compositions prepared according to the present invention are typically granular or powdered solids derived from food grade sugars, for use in energetic materials. The material has a density of ˜1.5 g/cc and moisture content in the range of from approximately 10% to approximately 30%. The fuel is insoluble in water and all common organic solvents. It is a combustible (not flammable) solid; and is non-volatile, non-melting, non-toxic, and non-irritating. The molecular formula is unknown and variable. The substance is a precipitated/coagulated carbohydrate colloid, and a polymer; consisting of the purified, particulate high molecular weight caramel color bodies. Based on limited C and H weight % analysis, with O determined by difference, atomic composition range on a unit carbon basis indicates an approximate range of C=1.0, H=0.8 to 1.5, O=0.4 to 0.7. It is understood that this approximate range is intended as a best guess and is not intended as a limitation.  
           [0028]    The fuels and explosive compositions prepared according to the present invention may be combined with other fuels, including for example with fuels prepared according to my earlier patent, U.S. Pat. No. 5,465,664. Although these fuels may be combined, there are some applications for which it might be preferable not to combine these fuels. For example, there are significant burn rate differences between fuels prepared according to the present invention and fuels prepared according to U.S. Pat. No. 5,465,664. In compositions prepared according to U.S. Pat. No. 5,465,664, the metallic compounds present in the compositions act as burn rate catalysts. A burn rate catalyst can make a product more energetic than is necessary or desired for some applications.  
           [0029]    Explosive compositions may be prepared using the fuel of the present invention. For example, gunpowders or black powder substitutes may be manufactured using conventional black powder production equipment. This involves the intimate mixing of an oxidizer, such as potassium nitrate, (concentration range approximately  70  to approximately 78%) with the fuel (concentration range approximately 22 to approximately 30%). The materials are introduced to a wheel mill as essentially dry powders. Small amounts of water may be added periodically during the extended mixing process to promote formation of a cohesive cake of mixed material. No chemical reaction is involved in this manufacturing process. The wheel mill crushes and uniformly mixes the individual oxidizer and fuel particles to yield a highly homogeneous mixture. Subsequent processing, such as pressing, drying, crushing (to produce granular particles of gunpowder), screening (to separate the product into selected screen size ranges), coating (usually with graphite for conductivity, flowability and enhanced water resistance), and packaging (typically into one pound containers) are conducted.  
           [0030]    Alternatively, explosive compositions of this type can be manufactured using extrusion mixing and granulation processes, using a damp paste mixture of the finely pre-ground fuel and oxidizer. The extruded particles of explosive compositions are then crushed and screened to the desired sizes (generally in the range of from approximately minus 20 US mesh—1.651 mm clear opening—to approximately plus 60 US mesh size—0.246 mm clear opening), and then packaged typically in one pound containers.  
           [0031]    Conventional black powder gunpowder bums incompletely when fired in a muzzle-loading gun, yielding a dirty, odorous smoke air emission (typically containing CO, CO 2 , H 2 O, H 2 S, SO x  oxides of nitrogen, particulates), and leaving a greasy solid residue, fouling the barrel of the gun and containing unburned gunpowder, charcoal, sulfur residues, and soluble potassium salts. Some estimates suggest that as little as 56% of a black powder gunpowder charge in a muzzle-loading gun is actually combusted. Pyrodex® gunpowder contains black powder and perchlorates as part of the oxidizer charge, and therefore also emits chlorine containing volatile and non-volatile emissions in addition to the normal emissions of combusted black powder. In cleaning a muzzle loading gun after black powder or Pyrodex® firing it is almost inevitable that the consumer will come into some degree of skin contact with these non-volatile residues. Substitute black powder prepared from potassium nitrate and the fuel composition of the present invention combusts cleanly and virtually completely, emitting only CO 2 , reduced CO, H 2 O, reduced oxides of nitrogen, and reduced particulate to the ambient air. The substitute black powder prepared according to the present invention provides for greatly reduced (comparable to that of smokeless powder) solid residue in the bore, consisting primarily of potassium salts. It also makes cleaning simpler and easier and greatly reduces skin contact with the minimal residues present. 
       
    
    
     EXAMPLES  
       [0032]    The inventor has formulated and tested a large number of pyrotechnic, gas-generating, and explosive compositions, including gunpowders and blasting agents utilizing the fuel components specified herein. All results have been superior with respect to burn rates, velocities, residues, etc. A few representative examples are discussed below.  
       Example 1  
       [0033]    Tray Loading  
         [0034]    Equipment Required: 8 each 17″×34″ stainless steel (“SS”) trays (pans); mixing hoe, mixing wide plastic spatula, 4 ea.—1 gal. milk jugs with water level calibration marks; 4 ea.—5 gal. plastic buckets; scale capable of 50 pounds capacity; lab balance capable of 500 grams capacity, or volumetric measure for catalyst; funnel; rubber gloves; dust mask, safety glasses or toggles.  
         [0035]    Materials Required: 50 # bags of fructose 5 gal. plastic bucket with tight lid containing crystalline oxalic acid catalyst (CAUTION!—poisonous), tap water.  
         [0036]    Personnel Required: one person  
         [0037]    Estimated Time: 1 hour  
         [0038]    Procedure:  
         [0039]    Using 50 # scale, weigh out 30 pounds of fructose into the 4 ea.—5 gal. plastic buckets.  
         [0040]    Fill each of the 4 ea.—1 gal. plastic milk jugs with tap water, to the calibration level line with 3.33 pounds of water (as exactly as possible).  
         [0041]    Wearing dust mask and rubber gloves, open the 5 gal. oxalic acid catalyst pail. Carefully weigh outs or measure out with calibrated measure 0.30 pounds (138 grams) of oxalic acid. Insert plastic funnel in turn into each of the 4—1 gallon jugs. Pour 1 measure of oxalic acid crystals into the jug through the funnel. Place cap on each jug. Shake or swirl water in jug until all oxalic crystals are dissolved. Close and seal the 5 gal. oxalic acid bucket.  
         [0042]    (Alternate to above 2 steps)—If large tank or barrel of pre-mixed oxalic acid/water solution (91.7% water, 8.3% oxalic acid crystals) is available, fill 4 ea.—1 gal plastic jug to calibration mark with solution from the tank or barrel.  
         [0043]    Place four of the SS pans on a large table. Completely empty one jug of the water/oxalic acid solution into each pan—pour carefully and do not splash.  
         [0044]    Carefully pour one bucket of the measured 30 pound fructose buckets into each SS pan—distributing the fructose over the pan surface.  
         [0045]    Using hoe and spatula, carefully mix fructose and water in each pan. Mix until uniform consistency is apparent, and no pools or areas of watery sugar solution are apparent on the surface and at the edges of the pan. Scrape wet sugar from hoe and spatula into the pan. Wash sugar residue from hoe and spatula.  
         [0046]    Autoclave Loading  
         [0047]    Equipment Required: Transfer table; heavy rubber gloves; safety glasses; 30 gal plastic barrel to collect autoclave condensate.  
         [0048]    Materials Required: 4 ea.—17″×34″ SS pans filled with catalyzed sugar solution.  
         [0049]    Personnel: 2 persons best.  
         [0050]    Estimated Time: 1 hour, plus periodic checks.  
         [0051]    Procedure:  
         [0052]    Using transfer cart, move filled SS trays from filling area to autoclave area.  
         [0053]    Starting from bottom slot, insert trays into slots in autoclave rack. Insert temperature probe into second pan from bottom so that probe tip is immersed in the fructose solution in the tray. Carefully arrange probe so that it will not be displaced by insertion of next tray. Insert top two trays into the slots in the rack.  
         [0054]    Close autoclave door securely.  
         [0055]    Make certain chamber bypass valve is closed, and chamber exhaust valve is open fully. Make certain manual selector control valve is in off position (allows steam to jacket only). Open steam supply valve on steam line. Observe jacket pressure slowly rise to ˜24 psig.  
         [0056]    Turn on condenser water for chamber condenser.  
         [0057]    Monitor temperature of probe in the #2 tray sugar solution. When temperature reaches ˜150° F. (estimated 20 to 30 minutes) turn manual selector lever to STER position. Observe chamber and jacket pressure, and chart temperature indicator. Jacket and chamber pressure should both equalize at ˜24 psig. Chart temperature indicator should steady out at about 124° C.  
         [0058]    Periodically check reading of temperature probe immersed in sugar solution. It should rise to a peak in the range of 280 to 290° F. within a period of about 30 to 60 minutes. After the peak is reached, temperature of probe will slowly fall off to about 270 to 280° F. at end of cook.  
         [0059]    Periodically check that chamber condensate is flowing to the condensate collection tank. Total condensate for a batch run should be in the range of 16 to 20 kg (4 to 5 gallons).  
         [0060]    Cook batch for 5 hours from time steam is admitted to chamber.  
         [0061]    Autoclave Unloading  
         [0062]    Equipment Required.: Transfer cart: full face respirator with organic acid canisters: heavy rubber gloves: full face shield; handheld pH meter; unloading area ventilation equipment; covered and ventilated product receiver-cooler bin; rubber mallet, steel bar or probe, and wire brush to dislodge product from trays.  
         [0063]    Materials Required.: sodium hydroxide flake or pellets.  
         [0064]    Personnel: 2 persons  
         [0065]    Estimated Time: ½ hour  
         [0066]    Procedure:  
         [0067]    Turn manual control valve on autoclave to fast exhaust position.  
         [0068]    When chamber pressure reaches 0 psig, turn control selector valve to dry (vacuum) position. Chamber pressure gage will slowly show increased vacuum—up to ˜5 Hg gage. Hold for 10 minutes. Then turn selector valve to Off position.  
         [0069]    Turn on switch to autoclave area ventilation system.  
         [0070]    Put on full face respirator and rubber gloves. Shut off steam supply valve. Cautiously open autoclave door when chamber pressure reaches 0. Avoid exposure to any residual fumes.  
         [0071]    Remove trays, starting with top tray. Be careful in removing tray in which temperature probe is immersed, so as not to damage probe. With slow, firm withdrawal force on tray, the temperature probe should pull out of the solid cake in the tray.  
         [0072]    As each tray is withdrawn from the autoclave, invert it over opening in product receiver-cooler bin. Knock out any solids retained in tray, and break up solid product cake with rubber mallet and steel bar so that all product falls into the receiver-cooler bin. Use steel brush to dislodge any solid residues in trays. Close cover over receiver-cooler bin, and leave the bin ventilation system on until ready to transfer product to size reduction process.  
         [0073]    CAUTION!—fumes are given off from the product solid as it is cooled, and as it is broken up, contain formic acid and acetic acid. Both of these are toxic and must not be released to the atmosphere or breathed by workers. Wear full face mask respirator in this area during operations.  
         [0074]    Check pH of scrubber water. Add crystalline sodium hydroxide to water to pH 9.0. Do not raise pH of scrubber water above the 9.0 value in order to minimize corrosion to the scrubber system. CAUTION!—sodium hydroxide is extremely corrosive, wear rubber gloves and full face shield when handling the dry sodium hydroxide.  
         [0075]    Product Drying and Packing  
         [0076]    Equipment Required: Dust mask, rubber gloves, scoops and buckets or barrels for product handling; dryer trays; moisture determination method equipment.  
         [0077]    Materials Required: none  
         [0078]    Personnel Required: one person.  
         [0079]    Estimated Time: 1-2 hours to load and unload, and to weigh and pack in barrels. Periodic checks of moisture level in product.  
         [0080]    Procedure:  
         [0081]    If drying required, load dryer trays with product in uniform layers. Place trays in tunnel cart. Load carts into dryer and seal.  
         [0082]    Start dryer fan and heat, if needed.  
         [0083]    Periodically remove a representative sample for moisture testing from top, middle and bottom trays. Determine moisture level of each sample. Refer to Batch Log Sheet for desired moisture level, and moisture calculation sheet for establishing average moisture level of entire charge. Continue run until moisture tests indicate achievement of specified moisture level or range.  
         [0084]    Turn dryer off. Remove carts from dryer. Unload trays onto mixing table. Mix contents of trays on mixing table to obtain uniform average moisture content. Take 3 samples, from different areas of the product on the mixing table. If moisture slightly high, leave contents on mixing table to air-dry further.  
       Example 2  
       [0085]    A 10.15 gram sample of pure granular fructose was placed in a covered beaker on a hotplate with magnetic stirbar. The hotplate was energized, and within 10 minutes the fructose was completely molten, at a temperature of approximately 140° F. As heating progressed, the boiling point of the melt was reached within 15 minutes at a temperature of about 220° F. At 20 minutes heating time the temperature was 242° F. At 261° F. a light yellow coloration was visible in the boiling melt. At 35 minutes of heating, the temperature was 315° F. color was a deep red-brown, melt appeared clear, condensed water was observed on the cover glass, and a burnt sugar smell was observed. Heating was continued and at 45 minutes the temperature of the stirred, boiling melt was 385° F., color was a dark red-brown, solution appeared clear, and a sweet, slightly acrid, odor was observed. At 55 minutes heating time, the temperature was approximately 400° F., color was red-black and opaque, odor was acrid-sweet, and viscosity of the melt increased rapidly, stopping the stirbar rotation. Rubbery strands of polymerized material could be pulled from the melt. At this point, heating was discontinued, and the material was allowed to cool. 100 cc of water was added to the cool, solid mass, and the mixture was boiled for 10 minutes. The entire liquid-slurry mix was filtered on a #42 Whatman filter paper (˜3 m pore size). The solids were washed with 50 cc of water, until clear liquid issued from the filter. The solids were dried and recovered from the filter paper. Filtrate was evaporated and residual dry solids content was recorded. Total weight loss was 3.07 grams (30.15% of original sugar weight). Insoluble polymerized caramel product retained by the filter was 4.42 grams (43.5% of the original sugar). The Filtrate contained both soluble caramel, and insoluble polymerized caramel product solids having a particle size &lt;˜3 m. The dry solid polymerized caramel product was crushed and ground in a mortar to produce an example of my new fuel for energetic materials. When compounded with potassium nitrate into a substitute black powder as described above, excellent gunpowder performance was obtained as mentioned above. The recovered dry solids from the filtrate were re-pulped with approximately an equal weight of water, and subjected to further heating. Within an approximate 35 minutes heating period, the water evaporated and virtually all of the solids had polymerized into the desired insoluble polymerized caramel fuel.  
       Example 3  
       [0086]    The experiment described in Example 2 was repeated with 29.00 grams of fructose, using a larger, stirred, covered container, and taking more detailed time-temperature data. After 56 minutes of heating, the polymerized caramel was obtained with a slightly higher end temperature of 413° F., before terminating the heating. A total weight loss of 32.03% was observed. The cooled solid product was crushed and ground in a mortar to yield the new fuel material. Similar appearance, handling and performance in an energetic material was found for the product of this experiment. I have conducted other experiments that demonstrate that the polymerized caramel fuel material can be produced by subjecting the sugar to a lower constant temperature, over a longer period of time.  
       Example 4  
       [0087]    I have found that by conducting the caramelization process on sugar mixed with varying proportions of water, the polymerized caramel fuel can be produced at lower processing temperatures over a prolonged processing time, with greatly facilitated formation and recovery of the water-insoluble polymerized product as fine particulate on a continuous or batch basis.  
         [0088]    For example, 505.31 grams of fructose was combined with 549.65 grams of water in a MIRRO M-0512-11, 12 quart capacity aluminum pressure cooker. Mixtures of water and sugar in this approximate concentration range are pumpable solutions at room temperature. The cooker was then covered, placed on a hotplate, purged of air, and brought to 15 psig operating pressure. The operating temperature was estimated to be in the range of 280° F., based on temperature measurements of the cooker metal wall near the bottom of the vessel. The cooker was maintained at this pressure for a period of 5 hours, after which it was cooled and opened. A red-brown slurry of dissolved caramel and suspended insoluble particulate polymerized caramel product was observed. pH of this slurry was approximately 3.0 as determined by an Omega PHH-3X handheld pH 1 meter. Recovery of the solids by filtering, evaporating and drying indicated a total weight loss of approximately 6.9% from the original sugar solids. Approximately 77.2% of the original sugar weight was present as insoluble fine and coarse particulate caramel fuel material.  
         [0089]    I have found that the solid particulate caramel material produced as described above has a size distribution ranging from &lt;3 m to agglomerates of up to about 10 USS mesh, and larger. This material produced in water slurry at lower processing temperatures appears to have superior energetic material fuel properties, including more versatile processability into gunpowder and similar energetic products and improved propellant ballistic performance—as compared to caramel material produced from sugar at higher temperatures with no water or other additions.  
         [0090]    I have found that the filtrate obtained from the pressure cook described above, containing water and soluble caramel and colloidal to micron sized insoluble caramel particles can be further processed under pressure cooking conditions described above to produce almost complete conversion to an energetic material fuel in any desired particle size range. That is, there is further caramelization and polymerization of the soluble caramel, and there is progressive growth of caramel particles.  
         [0091]    I have conducted numerous variations of these lower controlled time-temperature caramelization and polymerization experiments, in batch sizes up to 30 pounds of feed sugar solution, and with starting water content varying from a few percent to over 100%—all producing desired fuel for energetic material having desirable, tailorable subsequent processing and product properties. I have demonstrated that these caramel manufacture variations can be produced in batch or continuous fashion. Obviously, to one skilled in the art, there are numerous process, additive and processing equipment variations and options available to utilize which can advantageously simplify and enhance the caramel fuel production process.  
       Examples 5-8  
       [0092]    I have obtained 4 different samples of commercial caramel color (D. D. Williamson and Co. caramel colors Nos. 600, 604, 610 and 624—representing a wide range of available powdered commercial caramel color materials). I prepared substitute black powder compounds from each of these commercial caramels, using potassium nitrate as the oxidizer material, and demonstrated that all of the substitute black powders so prepared unexpectedly performed as suitable fuels for energetic materials, displaying a range of ignition, clean burning, and speed of burning characteristics related to their degree of caramelization.  
         [0093]    When appropriately compounded with a suitable oxidizer material (e.g. potassium nitrate, ammonium nitrate) the fuel material of the present invention produces energetic materials such as substitute black powders, rocket propellants, gun powders, blasting agents, and industrial explosives which have superior properties, including: high specific energy, clean burning, low pollution signature, improved safety, tailorable sensitivity to ignition, decreased flame signature, moderate cost, improved processability, non-hygroscopic, and improved shelf life. Various commercially obtainable caramel colors have been tested for use in the present invention. Varying, but acceptable results were obtained in all cases. Currently, the most preferred caramel color bodies for use in gunpowder or black powder substitute compositions are those derived from fructose.  
         [0094]    Other modifications, changes and substitutions are intended in the foregoing and in some instances, some features of the invention will be employed without a corresponding use of other features. For example, the fuel prepared using caramel color bodies may be used alone or may be used in combination with black powder or other black powder substitutes. Also, it is understood that the fuel prepared according to the present invention may be used in a wide variety of applications, including virtually any application that uses black powder or black powder substitutes. Further, it is understood that the fuel may be produced using either a wet or a dry process, the dry process being presently preferred. A wide range of raw materials, compositions and concentrations may be used. Of course, examples, measurements, and other numerical values and ranges are approximate, are given by way of example only and are not intended to limit the scope of the invention. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.
A fuel composition is disclosed that comprises insoluble caramel color bodies produced by the thermal degradation of carbohydrates. The fuel composition may be prepared using a carbohydrate such as a sugar and using an acid catalyst, such as using oxalic acid or citric acid. The fuel composition may be prepared by dissolving the carbohydrate in water to form a solution, and heating the solution over time so that a portion of the carbohydrate is converted to an insoluble polymer. The solution is preferably heated until at least approximately 40% by weight of the carbohydrate is converted to an insoluble polymer and is more preferably heated until it least approximately 50% by weight of the carbohydrate is converted to an insoluble polymer. An explosive composition may be prepared by combining an oxidizer with caramel color bodies. The caramel color bodies are preferably non-hygroscopic, have a neutral pH, and have a high molecular weight.