Abstract:
The invention is a new solid fuel combining coal and biomass and the process for making such fuel. The coal must be selected and prepared to be the correct sizes and quality, including the moisture content and levels of pollutants. Biomass must be selected and prepared by grinding and through a heating process in order to remove moisture and partially char the biomass. The biomass may be selected based on its percentage volume of carbon and hydrogen. A third material, binder is prepared in volumes to associate with the coal and biomass. The coal, biomass and binder are mixed in appropriate quantities and may be delivered to an extrusion, press pellet or briquetting machine that forms the mixture into an appropriate size and shape for the intended combustion situation. The resultant solid fuel has had desired properties for efficient burning and emission levels in the furnace for which it is designed.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not Applicable 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not Applicable 
       REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX 
       [0003]    Not Applicable 
       BACKGROUND OF THE INVENTION 
       [0004]    The present invention is in the technical field solid fuels. More particularly, the present invention is in the technical field utilizing a combination of materials to produce a fuel with high caloric content in the form of small briquettes or pellets, which, upon combustion, emit minimal amounts of pollutants. 
         [0005]    Conventional solid fuels, such as coal, biomass, and waste carboniferous materials, typically contain impurities and additional hazardous pollutants in the form of chemicals or chemical compounds varying from non-negligibly small, to minute amounts. These impurities, pollutants, or hazardous ingredients make solid fuels more costly to transport, reducing their efficiency of combustion, and causing hazardous emissions. The capture of these impurities, pollutants, or hazardous ingredients post combustion, requires complex processing and excess costs as the impurities, pollutants, or hazardous ingredients are widely disbursed in the combustion gases. Further, the coal, biomass or waste carboniferous material typically is not in suitable physical form for transport or introduction to a furnace. Often, during transportation or handling of coal and biomass, undesirable particulate or dust pollution is emitted and, while the coal, biomass or waste carboniferous material is too small to be held on the stoker grate used to introduce fuel to the furnace of a boiler. Failure to capture and contain this waste results in undesirable, as well as illegal contamination and pollution of the surroundings. 
         [0006]    The typical practice of attempting to ignite coal and biomass in separate burners of the same furnace, where the two components are not intimately combined prior to ignition, is inefficient with unintended/undesirable results. The combustion of heterogeneous solid fuels leads to altered flame temperature profiles, slagging, combustion inefficiency, increased ash, in addition to problems with grindability, fuel flow, and corrosion. 
         [0007]    Numerous natural and synthetic substances have been used as binders for forming/producing pellets and briquettes of coal. U.S. Pat. No. 3,966,427 teaches how to make coal briquettes using bitumen or bitumen emulsions as binders. Additional art is described in U.S. Pat. No. 5,244,473 which teaches that a binder for coal fines can be made from a phenol-aldehyde resin mixed with a polyisocyanate in the presence of a catalyst. U.S. Pat. No. 5,009,671 teaches that coal briquettes can be made by using a starch binder mixed with molasses and water. Further relevant art is described in U.S. Pat. No. 4,862,485, which teaches means for forming coal pellets by mixing coal particles with polyvinyl alcohol, calcium oxide and/or magnesium oxide and water. U.S. Pat. No. 4,738,685 teaches how to cold press coal fines with molasses, an inorganic hardening agent such as calcium carbonate, calcium phosphate, iron oxide, aluminum oxide and optionally with an acid. Additional teachings relevant, though differing from the present application can be found in U.S. Pat. Nos. 4,618,347, 4,586,936. 4,169,711 and U.S. Pat. No. 5,916,826. Patent application No. 20100162619 describes a method using a Mallard process at a pressure of 5 bar at an elevated temperature for compacting biofuels together with some limited amount of peat or lignite 
         [0008]    The present application describes unique and novel systems and methods for obtaining calorically rich combustible briquettes, relatively free of contaminants, consisting of coal and biomass which are new and novel, not featured in the aforementioned references. The biomass can consist of algae, switch grass, wood matter, such as sawdust and/or wood chips, as well as manure to mention a number of useful components, however not limited to such biomass materials. 
       BRIEF SUMMARY OF THE INVENTION 
       [0009]    The present invention is a new solid fuel combining coal and biomass, and other selected carboniferous solids into a homogenous, caloric high value solid fuel. The coal must be selected and prepared to have the correct size and quality, including the moisture content and levels of pollutants. Biomass must also be selected and prepared to have the appropriate be size and quality, including moisture content and levels of pollutants. An essential factor is that the biomass be selected based on its percentage relative to volume of carbon and hydrogen. A third additional material that can be used is a binder, prepared in appropriate volumes so as to efficiently bind the coal and biomass. The coal, biomass and binder are mixed in appropriate proportions that may be delivered to a machine that forms the mixture into extrusions, pellets or briquettes, with the resultant solid fuel having more desired properties for efficient burning with substantially reduced levels of emissions. Emissions are effectively removed and captured by the kilns used in the present process. The pollutant gases can also be reprocessed since many have commercial value. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  is a flow chart indicating the steps for producing the compressed pellets or briquettes of coal and biomass. Described are the loading, processing, and unloading of the final pellet/briquette product. 
           [0011]      FIG. 2  is a block diagram of the various components used to form the final coal-biomass product. Here, a binder can be used to aid in combining the coal and biomass, but the use of a binder is an option. 
           [0012]      FIG. 3   a  is a shredding or chipping machine to cut the biomass into small pieces in order to be able to combine them with the crushed coal. 
           [0013]      FIG. 3   b  shows a crusher that is used to create small pieces of coal from the original coal input. 
           [0014]      FIG. 3   c  shows a kiln, a first such kiln used to prepare the coal by eliminating some of the moisture and unwanted polluting volatiles of the coal, a second such kiln used to prepare the biomass where the kiln removes moisture and volatiles. 
           [0015]      FIG. 3   d  is a duct for liquefying valuable hydrocarbons emitted in heating coal in the first kiln. 
           [0016]      FIG. 3   e  illustrates the mixing machine for combining the crushed coal after processing in the first kiln, the coal then known as coal char, the shredded biomass and the liquefied hydrocarbons emanating from a duct connected to the first kiln, with the liquefied hydrocarbons acting as a binder between the coal char and biomass. 
           [0017]      FIG. 3   f  is a schematic of the briquetting machine which receives the mixture of coal, biomass, and the liquefied hydrocarbons, the latter acting as a binder. The briquetting machine compresses the material from the mixer through one or more dies to produce brick, briquettes or pellets. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Referring to the flow chart  FIG. 1 , the coal-biomass process begins with coal  101  loaded into a raw coal crusher  102  to reduce coal to any desired size. The coal may be as small as ¼ inch in any dimension. Once crushed or ground, the coal contents pass from crusher  102  to the first kiln  103 . The average temperature of the kiln is on the order of 500 C. which drives off moisture and certain volatiles, some of which are contaminants, the contaminant volatiles entrained or sequestered in a clean up station, while other volatiles are in the form of useful gaseous hydrocarbons. The valuable hydrocarbon gases are driven off from kiln  103  and can be transferred to clean coal tar duct  104  where the hydrocarbon gases are liquefied. This is an optional but useful step in the overall process. In all cases, the solid contents of kiln  103  are transferred to the coal biomass mixer  106 . For the case where duct  104  is used to produce liquefied hydrocarbons, the liquid from  104  is transferred to mixer  106 . 
         [0019]    Biomass  109  consisting of for example of tree thinning, forest waste, algae, crops grown for fuel, or waste from agriculture, food, or drink processing, is loaded into the biomass shredder/shredding machine  110  shown in  FIG. 3   a . After shredding, the contents of  110  are transferred to second kiln  111  where the biomass is heated to specified temperatures, usually on the order of 230 C., to remove unwanted moisture (water) and unwanted gases including Hg, Cl, and the like. 
         [0020]    The contents of second kiln  111  are further transferred to the coal and biomass mixer  106  where the two sources of fuel are thoroughly mixed. In the preferred embodiment, clean coal tar from duct  104  is also transferred to the mixer  106  to act as a binder between the coal char from first kiln  103  and the biomass entering the mixer  106  from second kiln  111 . The contents of the binder material from duct  104  will generally consist of coal tar, bitumen, or emulsions of such materials. Once the material in the coal and biomass mixer consisting of coal char, biomass and the liquefied coal tar from duct  104 , is thoroughly combined, the content is transferred to the briquette or extruder device  107 . The extruder device  107  produces the finished coal-biomass product  108  in the form of pellets or briquettes. 
         [0021]      FIG. 2  is a block diagram showing the components used in the formation of coal and biomass briquettes or pellets. The entrance of coal  206  into coal crusher  207  is followed by the entrance of the crushed coal into the first kiln  208   b . The output from the first heated kiln  208   b  in the form of coal char is transferred to mixer  204 . In addition, in an alternate preferred embodiment, the hydrocarbon volatiles from first kiln  208   b  can be transferred to duct  209  where the duct temperature allows useful hydrocarbon gases to liquefy. The liquefied hydrocarbons are then also transferred to mixer  204  from duct  209 . Biomass  201  enters shredder  202  where it is cut into suitable sizes to then be transferred to second kiln  203 . The heat from kiln  203  releases volatiles and water vapor, both of which are entrained in two separate cleanup stations. The dried biomass is then transferred to mixer  204 . In the preferred embodiment the contents of mixer  204  are coal char from first kiln  208   b , liquefied hydrocarbons from duct  209  and biomass from second kiln  203 . After thorough mixing in mixer  204 , the contents of mixer  204  are transferred to the briquetting machine  205  then the output in the form of coal-biomass briquettes are collected in output container  210 . 
         [0022]    Referring now to  202  in  FIG. 3   a , biomass  326  enters the proximal end of shredder  202  through a fixedly attached open flange  326   a  at the proximal end of  202 . A motor driven piston  327  extends within the interior of shredder  202  with cutting blades  327   a  attached to the lower portion of piston  327 . A motor, not shown explicitly in  FIG. 3   a  drives piston.  327  and thereby blades  327   a  to shred biomass  326  into small portions, on the order of ¼ to 2 inch lengths. The shredded biomass is carried from the proximal end of shredder  202  to the distal end by a conveyor belt  328  in order to remove the biomass from shredder  202  through the distal end with a fixedly attached open flange. 
         [0023]      FIG. 3   b  describes coal crusher  207  where coal  206  enters the proximal end of crusher  207  and is transported from proximal to distal end of  207  by moving belt  302 . The crushed coal is illustrated by  301  while the crushing mechanisms are a piston  303  extending into the interior of  207 , driven in an up and down motion by a motor not explicitly shown. The crushed coal exits through  304   a  to which is fixedly attached open flange  304 . 
         [0024]      FIG. 3   c  illustrates the first kiln  208   b  and second kiln  203 . Both kilns are functionally identical but with possible variations in their dimensions and the operational temperatures required for the present invention. The biomass exiting the distal end of shredder  202  enters second kiln  203  while crushed coal from the distal end of  207  enters first kiln  208   b . The contents of each kiln  203  and  208   b  during pyrolysis is indicating by  310 , consisting in kiln  208   b  of coal, coal char and coal volatiles, and kiln  203  of biomass and biomass volatiles. Both first and second kilns,  208   b  and  203  respectively, have a proximal and distal end, each with fixedly attached open flanges  307  and  311   a  respectively. In first kiln  208   b , crushed coal enters through the fixedly attached open flange  307   a  by way of an airlock  307 , the airlock preventing oxygen/air from entering first kiln  208   b  and second kiln  203 . The proximal end of first kiln  208   b  is maintained at temperatures in the range 175 to 250 C. while the distal end is maintained at a temperature at a range of ˜350-500 C. The proximal and distal ends of second kiln  203  are maintained at a temperature range of 100-150 C. at the proximal end and a temperature range of 200-275 C. at the distal end. Temperatures are controlled by heat coils  309   b  wrapped around outer kiln shell  305 , coils  309   b  attached to a control power unit (not shown) to provide heat to coils  309   b . The crushed coal in kiln  208   b  and the shredded biomass in kiln  203  are transported from proximal to distal ends of kilns  208   b  and  203  respectively by means of rotation of kiln core  305  of kilns  208   b  and  203  by action of a helical steel rail fixedly attached to the inner kiln core  305 . In first kiln  208   b , hydrocarbon gases evolved in heated kiln core  305  from the crushed coal which transforms to coal char due to the heating in first kiln  208   b , exit by way of airlock  308  and through the fixedly attached open flange  311   a . The proximal end of both first and second kilns  208   b  and  203  respectively, have a low temperature volatile cleanup station  309 , functioning mainly to trap water vapor, disposed at their proximal ends and a high temperature cleanup station  309   a  to capture high temperature volatiles such as mercury, sulfur and chlorine, mounted at the distal ends. 
         [0025]    Referring now to  FIG. 3   d , the hydrocarbon gases  320  of first kiln  208   b  are directed, in one embodiment to duct  209  through the fixedly attached open flange  320   a  of duct  209 . The temperature of duct  209  is maintained at 200-350 C. at the distal end and between 175-250 C. at the proximal distal end of duct. Duct temperature is sensed through a temperature sensor  321  which sends a signal to a master control unit (not shown). Sensor  321 , in conjunction with the control unit determines the power to heating coils  321   a  and thereby the temperature of duct  209 , with heat coils  321   a  wrapped to be in intimate contact with the outer surface of duct  209 . Legs  323  and  324  supporting duct  209  are of two different lengths so that duct  209  is slanted thereby allowing the liquefied gases in duct  209  to flow by gravity into mixer  204  shown in  FIG. 3   e  via the fixedly attached open flange  325   a  attached to the distal end of duct  209  and into one proximal opening with a fixedly attached open flange  313   c  of mixer  204  shown in  FIG. 3   e.    
         [0026]    In an alternate embodiment, the gases and coal char of first kiln  208   b  are directed through the fixedly attached open flange at the distal end of first kiln  208   b  to the mixer  204  shown in  FIG. 3  through a proximal  313   a  opening and a fixedly attached open flange at the proximal end of mixer  204 . 
         [0027]    The biomass from shredder  202  is directed through the open flange fixedly attached to the distal end of shredder  202  where low temperature volatiles are taken up or entrained and treated in cleanup station  309  and high temperature volatiles are taken up or entrained by the high temperature volatile cleanup station  309   a . The heat treated shredded biomass is transferred to an open end with a fixedly attached open flange of mixer  204  shown in  FIG. 3   e . Mixer  204  has internally mounted rotating blades  314  to achieve the mixing where mixing combines the coal char from first kiln  208   b , the liquefied hydrocarbons from duct  209  and the biomass from second kiln  203 , the coal char entering through proximal opening  313 , biomass from second kiln  208  through proximal opening  313   b  and the liquefied hydrocarbons through proximal opening  313   c , where each proximal opening has a fixedly attached open flange. 
         [0028]    After mixing of biomass, coal char and liquefied hydrocarbons in mixer  204 , the contents of  204  pass through the distal end of mixer  204  where the distal opening is fixedly attached to an open flange and enter the briquetting device  205  shown in  FIG. 3   f  though a proximal opening with a fixedly attached open flange  316 . Device  205  has a rotating screw  317  which carries the mixture of biomass, coal char and liquefied hydrocarbons from the proximal end to its distal end of  205 . At the distal end of  205  a die  318  is fixedly attached causing the material carried by rotating screw  317  to be extruded into briquettes bricks or pellets, depending on the particular geometry of die  318 . The extruded product is collected in container  210 . 
         [0029]    While the foregoing written description of the invention enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The invention should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the invention as claimed.