Abstract:
Solid carboniferous fuels contain varying quantities of moisture, mercury, chlorine, nitrogen, sulfur, heavy metals and other materials that attain vapor pressure at elevated temperatures. The cost effective removal of these degrading and sometimes hazardous materials is important to the further use of the fuel for combustion as a solid, liquid, or gas. The solid fuel is cut, shredded, ground or sieved to appropriate size, and heated in a chamber that can exclude oxygen and air thus preventing ignition. The unwanted materials are driven in the gaseous state and extracted for disposal. The solid fuel cleaned of pollutants exits the chamber and is cooled below ignition temperature prior to contact with oxygen. The solid fuel thus purified is more appropriate for combustion, liquefaction or gasification due to the reduced costs in use as a fuel or in the post combustion clean up.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
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     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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     REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISK APPENDIX 
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     FIELD OF THE INVENTION 
     The present invention relates to the general topic of clean fuels for use in future combustion. The need for clean fuels is urgent to prevent further worldwide air pollution by harmful contaminants inherently present in nearly all carboniferous fuels. These contaminants, if not removed from the fuel feed stock are either released upon combustion, or costly to remove after liquefaction or gasification. Typical fuels are coal and the hydrocarbons that can be released from coal, and numerous biomass species such as switch grass, wood, bone, algae, and peat to mention the most common. Since many of the contaminants are harmful to all forms of life, a considerable effort has been undertaken over the last several decades to find ways to release and capture these contaminants prior to combustion. Some of these contaminants can then be re-processed for useful purposes while some must be sequestered or safely disposed of in other ways. The present invention provides novel means for releasing and capturing most of the inherent contaminants prior to the numerous existing pyrolyzing and hydrolyzing processes, thereby giving rise to a more efficient and less costly way for obtaining a contaminant free fuel. By removing water vapor and other contaminants such as Hg, Cl, S, As and the like, a more efficient hydrolysis process can take place to cause the resulting to be cheaper, less polluting and to have higher caloric value. 
     BACKGROUND OF THE INVENTION 
     Coal and biomass hydrolysis, in which a portion of coal and/or biomass is converted into a series of useful, high caloric gases, was first developed as early as the eighteenth century. However, commercial conversion to liquid or gas became more widespread in the early to mid 1900&#39;s. Intense renewed interest in pyrolysis to upgrade a variety of raw coals was spurred by the tensions between the West and the oil rich nations of the Middle Eastern countries in the 1970&#39;s. In general, depending on the nature of the raw coal and/or biomass in addition to the exact nature of the pyrolysis process, the gas and char from coal and biomass pyrolysis generally contains water vapor, and compounds of chlorine, mercury, additional heavy metals, hydrogen sulfide, and a range of hydrocarbon volatiles. Any solid, non-volatized coal char will contain carbon, a range of hydrocarbon compounds, and traces of other minerals and elemental compounds. The volatized gases can be separated and the individual gaseous products can be further processed for useful chemical applications. At the same time, burning coals and biomass that have been properly pyrolyzed, reduces air pollutions and hence human health hazards such as emphysema, asthma, and lung cancer. The large number of issued patents involving pyrolysis, liquefaction or gasification of coal gives a broad picture of the utility and profitability of the conversion of coal to achieve a cleaner hydrocarbon fuel. 
     The history and detailed time-line of coal pyrolysis are well documented and found on a variety of websites. Details of a pyrolysis process can be found, for example, in “Kinetic Studies of Gas Evolution During Pyrolysis of Sub-bituminous Coal,” by J. H. Campbell et al., a paper published May 11, 1976 at the Lawrence Livermore Laboratory, Livermore, Calif. Numerous issued U.S. patents describe methods for the reduction of sulfur in coal, for example, U.S. Pat. No. 7,056,359 by Somerville et al. Their process involves grinding coal to a small particle size, then blending the ground coal with hydrated lime and water, followed by drying the blend at 300-400 degrees F. U.S. Pat. No. 5,037,450 by Keener et al. utilizes a unique pyrolysis process for denitrifying and desulfurizing coal. Here the sulfur and nitrogen content of coal is again driven off in gaseous form and sequestered for possible further use. 
     Related 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 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. 
     A more recent system has been proposed and published as USPTO application 20090020456 (Jan. 22, 2009) by Tsangaris et al, relating to the gasification of fossil fuels, fuels which are then used to process a variety of unconventional sources of oil sources such as tar sands and shale oil. 
     The present application describes unique and novel systems and methods for obtaining calorically rich combustibles, nearly contaminant free combustibles for gasification consisting of coal and biomass. The invention involves the preprocessing of the coal and biomass so resulting in major energy saving during the gasification stage. The biomass can consist of algae, switch grass, wood matter, such as sawdust and/or wood chips, as well as manure to mention a non-exhaustive number of useful caloric components. 
     One of the several ways the present invention is particularly efficient is that it greatly reduces the water vapor that is released from coal and biomass upon heating in a typical kiln. The fuel to be gasified which has already had the water removed makes the gasification considerably more efficient. At the same time, other contaminants such as S, H 2 S, Cl, Hg and several heavy metals which have also been removed prior to gasification increases the efficiency and quality of the gasification process. Some of these pollutants can then be reprocessed for further useful applications. This form of waste management is becoming recognized world wide as a necessary and achievable goal to reduce air pollution and potential global warming. 
     While some of the waste products from the burning of fossil fuels and biomass can be-recovered or recycled, most are disposed of in landfill. This type of disposal is wasteful and in itself potentially polluting, clearly not an environmentally friendly or economical way to proceed. Various government agencies have now put laws into effect that make certain forms of this type of disposal illegal which can result in substantial fines. 
     SUMMARY OF THE INVENTION 
     The present invention describes an apparatus and method for pre-processing coal and biomass that save energy in the gasification process. Specifically, the pre-processing kiln is attached to a water cleanup station to capture the water vapor that is released near the proximal end of the kiln. A wet scrubber is attached near the distal end of the kiln to capture pollutants and certain hydrocarbons prior to gasifiction. The removal of both the water vapor and the pollutants greatly reduces the cost of the gasification process. Means for sizing the coal and biomass also aids in the efficiency of the gasification process. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1  is a flow diagram illustrating the successive steps required for pre-processing of biomass and coal to be brought to a clean and near contaminant-free condition for efficient gasification. 
         FIG. 2  is a block diagram illustrating the components of the invention and their interconnections to bring the raw coal and or biomass into a state essentially free of water vapor and pollutants for subsequent efficient gasification or liquefaction. 
         FIG. 3  illustrates a biomass sizing tool consisting of a biomass cutting/shredding device, designed to bring the biomass into a desired shape or volume for further efficient processing. A side and cross sectional end view are shown. 
         FIG. 4  is a sketch of the coal sizing tool for crushing coal, the device takes feedstock coal and crushes it to the desired shape or volume for subsequent efficient processing prior to gasification. Both a side and cross sectional end view are shown. 
         FIG. 5  a show a side view of the kiln used for pre-processing the coal and bio fuels prior to gasification.  FIG. 5   b  shows a part of the kiln in cross section along with a motor drive to provide rotation of the kiln during pre-processing of the coal and biomass.  FIG. 5   c  is a perspective drawing of the hopper, attached to the kiln, where the hopper receives the coal and biomass after each has been cut to the desired size by the respective biomass and coal sizing tool. 
         FIG. 6  is a sketch of the master control module that senses temperature of the kiln and in turn controls the temperature of the kiln by way of the kiln heater coils. The module also determines the rate/speed of rotation of the kiln core mechanism. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention describes a system and method for pre-processing coal and biomass prior to gasification. The basic components utilize, a source of coal and biomass that brings the coal to a desired size using a first sizing tool for reducing the coal to maximize efficiency a second sizing tool to cut or shred the biomass to the optimum size for operation in the a kiln. The main objective is to remove as much water and other contaminants in the kiln prior to the step of gasification of the kiln contents. The kiln is one that has an outer shell and an inner core concentrically positioned within the outer shell, the inner core free to rotate within the outer shell. The kiln temperature is controlled by way of master control module which also controls the speed of rotation of the inner kiln core, receives signals from the thermal sensors within the kiln and regulates the oscillatory motion of the two sizing tools which operate by way of a motor that causes and up and down motion of a piston to shred the biomass and crush the coal to their desired sizes. The thermal signals also are used to regulate the temperature of the kiln by way of heater coils affixed to the outer surface of the kiln outer shell. 
     The sized coal and biomass are directed to a hopper by way of a chute from each sizing tool, where the hopper is affixed to the proximal end of the kiln and where the proximal end has an airlock attached to the kiln outer shell so that the coal and biomass can enter the kiln without admitting oxygen to the kiln. On heating of the coal and/or biomass, water vapor is emitted and drawn off to a water cleanup station by way of a duct extending from near the kiln&#39;s proximal end. The water can then used to generate steam in a separate steam generator unit which provides high pressure steam for operation of a gasifier that processes the pre-processed coal and biomass from kiln. A duct is positioned near the distal end of the kiln, to withdraw gaseous contaminants such as Cl, Hg, S, Se, and As and some hydrocarbons into a wet scrubber which separates and sequesters the contaminants for future use or safe disposal. The useful hydrocarbons can also be sequestered separately for further use. 
     Typically the kiln temperature is controlled by the master control unit in order to maintain the proximal kiln in the range 125-200 C, the distal end in the range 450-500 C. The sized coal and biomass enter the kiln&#39;s proximal end though the airlock; are heated without combusting, and exit the kiln at the distal end at the higher temperature with the help of a screw drive. The solid contents of the kiln are moved from proximal to distal end by way of a helical steel rail firmly affixed to the inner surface of the kiln core upon rotation of the kiln core. 
     The coal sizing tool is a container with one open end with a chute at the opposite end through which the coal exits after sizing. A centrally located piston, has one end within the container connected to a perforated block, with the opposite end located exterior to the sizing tool container. The exterior part of the piston is connected to a motor to cause the piston to undergo vertical oscillatory motion, by crushing the coal within the container to the desired size. The size will be determined by the rate of oscillation and the impact produced by the crusher. The coal moves from the proximal to the distal ends of the sizing tool by way of a conveyor belt positioned at the bottom of the sizing tool container. The preferred volume of the exiting coal is in the range of 0.25-10 cm3. 
     The biomass sizing tool is a container, open at its front end with a chute attached to the opposite open end through which the biomass exits. The motion from front (proximal) to distal ends makes use of a conveyor belt located at the bottom of the sizing tool. A piston extends into the container with a block attached to the piston and a set of blades attached to the bock. The opposite end of the piston extends outside of the container and is driven by a motor to provide vertical oscillatory motion to the piston and thereby to the blades to produce cutting of the biomass to a preferred size, preferably in the range of 0.25-40 cm3. 
     The important novelty of the present invention is to provide a system that receives pre-processed coal and or/biomass for further gasification where the pre-processing eliminates most water vapor from the coal and biomass as well as the contaminants. This pre-processing results in a more efficient, cost saving way to gasify coal and biomass where the coal and biomass exit the kiln as a pre-heated char, substantially free of pollutants that would be more costly to remove during the gasification or liquefaction process. 
     The Invention can be further understood by referring by referring to  FIG. 1  where  100  describes the steps of the process invention in conjunction with  FIG. 2  which indicates the block diagram in  200 . The start of the process is described in  FIG. 1  and starts at  1001 . This is followed by the loading  101  of coal, the loading  102  of biomass, each into their respective sizing tools to provide the desired sizes of each. The coal is crushed  103  and the biomass is cut or shredded  104 . Biomass and coal are collected  105  in collection hopper  105  to be heated in heated kiln  106 . Kiln heating results in the emanation of vapor and contaminants which are released from the coal and biomass in the kiln. Cleaning of the hot water vapor  108  from the kiln occurs in a water clean-up station while the other contaminants are wet scrubbed and separated in step  107 . Steam is generated instep  111  from the hot water vapor and released for the gasifying process  112 . Some valuable hydrocarbons initially mixed with the contaminants are released  109  from the wet scrubber and directed to be further gasified  112 . Kiln heat also results in char formed from the hot coal as well as hot biomass, both of which are released in step  110  from the kiln and then further released to be gasified  112 . 
     The steps indicated in  100  are further clarified the block diagram,  FIG. 2. 201  and  202  show the initiating steps of available coal and biomass respectively. Coal  201  is fed into sizing tool  204  for obtaining a desired size of coal while biomass  202  is directed into biomass sizing tool  203 . The contents of  203  and  204  are directed into hopper  212  by way of separate conveyor belts within sizing tools  204  and  203  (not shown here). Hopper  212  is fixedly attached to kiln  207  where the water vapor developed in the heated kiln near the kiln&#39;s proximal end is directed to a water clean-up station  205 . After clean-up, the water goes to a steam generator  209  where the steam is then directed into gasifier  211 . Contaminants that are given off in heated kiln  207  are drawn off near the distal end of kiln  207  and directed to a wet scrubber that separates and sequesters contaminants from useful hydrocarbons of the type CxHy and directs them to a tank  208 . Subsequently the contents of  208  are directed into gasifier  211 . The fully pre-process heated contents of kiln  207 , consisting of heated biomass and char are emptied into container  210  and then sent by a conveyor belt to gasifier  211 . The hydrocarbon contents of  208  are also directed into the gasifier. 
       FIG. 3   a  illustrates the biomass sizing tool  203  shown here in a side view. The side view, shows a portion of piston  301  exterior to the sizing tool container  306 , where exterior portion of piston  301  is connected to a motor (not shown) to cause  301  to move in an oscillatory motion with the lower part of piston  301  extending into the interior of container  306  and rigidly attached to block  302 . Block  302  is in turn fixedly attached to cutting blades  303 . A conveyor belt  304  moves the biomass from the proximal to the distal end of sizing tool  203 . The distal end of  203  is attached to chute  305  for emptying the contents of the sized biomass to hopper  212  shown in  FIG. 2 . 
       FIG. 3   b  shows the cross sectional view of sizing tool  203  with piston  301 , block  302 , blade  303  and belt  304 . The double headed arrow indicates the up and down oscillatory motion of piston  301 . 
       FIG. 4  indicated by  400  shows details of coal sizing tool  204 . The side view is shown in a) of  FIG. 4 . A portion of piston  401  is shown outside of coal sizing tool container  406  while a portion of piston  401  extends into the interior of container  406 . The end of piston  401  extending into container  406  is attached to block  402  and block  402  is attached to a crusher  403 . A conveyor belt  404  moves the crushed coal from the proximal to the distal end of container  406 . The distal end of  406  empties the crushed coal by way of a chute  405 . The vertical arrows indicated the oscillatory motion of piston  401 . A cross sectional end view of the coal sizing tool is shown in b) of  FIG. 4  with piston  401 , block  402  and crusher  403  as well as conveyor belt  404 . 
       FIG. 5   a  in  500  shows details in a side view of kiln  207 , water cleanup station  205  and wet scrubber  206 . Kiln  207  consists of an outer shell  501  and has a concentrically mounted, rotatable inner core  502 . Kiln shell  501  has heater coils  506  wrapped around its outer surface. Heat sensors  507  are mounted in the annular space between inner core  502  and outer shell  501 . Kiln rotation mechanism  503  is further described in  FIG. 5   b . An airlock  505  mounted at the proximal end of shell  501  admits the contents of coal and biomass in hopper  504 . Airlock  505  prevents air (oxygen) from entering kiln core  502  so that the kiln can be heated without combustion. A helical steel rail  508  mounted onto the inner surface of kiln core  502  causes the contents of kiln core  502  to move from proximal to distal ends upon rotation of kiln core  502 . Char ejection screw drive  509  is mounted at the distal end of outer kiln shell  501  serving to discharge the pre-processed coal and biomass from kiln core  502 . Open flange  511  at the proximal end of kiln shell  501  connects kiln shell  501  and kiln core  502  to hopper  504  in conjunction with airlock  505 . At the distal end, flange  510  fixedly attached to outer shell  501  and outer shell  501  to eject the solid contents of kiln core  501 . Duct  514  connects the proximal end of the kiln shell  501  to the clean-up water station  205 , while duct  515  connects the distal end of kiln  501  to the wet scrubber. The output of  205  goes to steam generator  209 , and the hydrocarbon output of wet scrubber  206  goes to gasifier  211 . 
       FIG. 5   b  shows a cross section of the kiln rotation mechanism  503 . Gear  516  is attached to a motor (not shown) and engages gear  513  which is fixedly attached to the outer circumference of kiln inner core  502 .  FIG. 5   c  is a perspective drawing of hopper  504 . Shown is flange  511  which is fixedly attached to both hopper and kiln outer shell  501 . The drawing indicates the opening  512  which connects hopper  504  to kiln airlock  505 . 
       FIG. 6  is a schematic sketch of the master control module  600 . The control box  601  receives signals  602  from temperature sensors. Control box  601  also sends out signals  603  to control the rotation of gear  516  in kiln rotation mechanism  503 . In addition box  601  sends out signals  604  to control the temperature of kiln heater coils  506  and controlling signals  605  to control the motion of conveyor belts  304  and  404 . Signals  606  control motion of pistons  301  and  401 . 
     Given this disclosure it will become apparent to one skilled in the art that alternative equivalent embodiments are possible. These equivalent embodiments are also within the contemplation of the inventors.