System and Method for Cleaning Coal and Biomass in Efficient Integration with Fuel Delivery to a Boiler

Abstract

A system and method for drying, cleaning and upgrading coal and biomass solid fuel while integrating the steps with the normal on site steps in coal preparation for a utility boiler, such that boiler efficiency is improved and emissions are reduced. The present invention carefully sequences steps to employ latent heat from one step to the next and more efficiently bring the fuel up to or near ignition temperature. The present invention incorporates several previously related inventions to improve the heat content and cleanliness of the fuel, thus reducing fuel flow rate, ash, CO2, CO, NOx, sulfur, mercury, chlorine, particulate and other emissions, for the same or higher energy output.

I claim: 
     
         1 . A system located at the site of a boiler for obtaining clean coal and biomass, the system comprising; a boiler, said boiler an integral part of a power plant, said boiler having a flue stack for the release of hot flue gasses and an input nozzle for the combustion of solid fuel; raw coal and biomass, further comprising means for the receipt of said raw coal and biomass at site of said boiler; a crusher located at the site of said boiler with means for loading and crushing said coal; a shredding device located at the site of said boiler with means for loading and shredding said biomass; a fluidized-bed gravity separation device located at the site of said boiler, said device receiving and mixing said coal and biomass from said crusher and said shredder respectively together with hot flue gas from said boiler; a pulverizer located at the boiler site with means for receiving coal and biomass from said gravity separation device, said pulverizer further powdering said coal and biomass mixture emanating from said gravity separator; a rotating heated kiln located at the site of said boiler with means for receiving coal and biomass from said pulverizer, and means for transferring said coal and biomass from said pulverizer to said kiln; said kiln further comprising thermal means for removal of hazardous effluent gasses evolved from said coal and biomass in said heated kiln, further comprising means for transferring pyrolized coal and biomass from said kiln to said input nozzle of said boiler. 
     
     
         2 . A system as in  claim 1  wherein said boiler comprises an input boiler nozzle, said nozzle receiving said coal and biomass mixture from said kiln. 
     
     
         3 . A system as in  claim 1  wherein hazardous effluent gasses evolving from said coal and biomass mixture in heated kiln are selected from the group of gasses consisting of chlorine, mercury, arsenic, selenium and heavy metals, further said kiln system comprising means for capturing and sequestering said gasses. 
     
     
         4 . A system as in  claim 1  wherein said fluidized gravity separation device receives hot flue gasses from said power plant stack to mix, heat and dry said coal and biomass from said crusher and said shredding device respectively while separating the heavier and lighter mass of mixed coal and biomass. 
     
     
         5 . A system as in  claim 1 , wherein said pulverizer receives said coal and biomass mix from said fluidized gravity separator. 
     
     
         6 . A system as in  claim 5  wherein said pulverizer comprises means for sizing coal and biomass content mix, said pulverizer further comprising means for the delivery of its contents into said input of said kiln. 
     
     
         7 . A system as in  claim 6  wherein the contents of said kiln are heated, said contents further exiting from said kiln in the temperature range of 200-300 C. 
     
     
         8 . A system as in  claim 7  wherein the exiting heated contents of said kiln enter said nozzle of said boiler. 
     
     
         9 . A method for receiving and sizing coal and biomass at the site of a power plant, followed by cleaning the coal and biomass from major pollutants, the method comprising the steps of: loading the delivered coal into a raw coal crusher; loading the delivered biomass into a biomass shredder followed by transferring said coal and biomass content into a heated fluidized-bed gravity separator; transferring said crushed coal and shredded biomass contents from said gravity separator to a pulverizer; transferring the contents from said pulverizer to a pyrolyzing kiln for heating and removing contaminants from said coal and biomass content at a predetermined elevated temperature; transferring said heated contents from said kiln to a boiler, said boiler having a stack emitting hot flue gasses. 
     
     
         10 . The method of  claim 9  wherein said crusher provides a means for breaking said coal into smaller pieces in the size range of 5 cm or smaller. 
     
     
         11 . The method of  claim 9 ) wherein said shredder includes means for cutting said biomass into suitable sizes of 5 cm or less for said pulverizer. 
     
     
         12 . The method of  claim 9 ) wherein said fluidzed gravity separator mixes said coal and said biomass from said crusher and shredder with said boiler flue gases for injection to a pulverizer, said pulveriser comprising means for further combining and powdering said mixed coal and biomass content into smaller particles of coal and biomass. 
     
     
         13 . The method of  claim 12  wherein said powdered particles are in the range of 50 microns or smaller. 
     
     
         14 . The method of  claim 9 ) wherein said heated kiln receives said mixed coal and biomass particles from said pulverizer, said heated kiln further comprising means for removing and sequestering unwanted contaminants from said coal and biomass mixture. 
     
     
         15 . The method of  claim 14  where said contaminants are at least one of contaminants selected from the group of contaminants consisting of chlorine, mercury, nitrogen, sulfur, arsenic, selenium, and other heavy metals. 
     
     
         16 . The method of  claim 15 ) wherein the temperature of said heated decontaminated coal-biomass output from said kiln is in the range of 200-300 C. 
     
     
         17 . The method of  claim 9  wherein said boiler comprises an intake nozzle for receiving said coal and biomass contents from said heated kiln.