Conversion of waste into highly efficient fuel

Abstract

Solid combustible waste materials are converted into highly efficient fuel by subjecting such materials to size reduction in suitable size-reducing equipment. The last piece of the equipment is a mill which pulverizes the waste materials into fine particles having a high surface to mass ratio and forming a highly efficient fuel when these particles are directly injected into a combustion reactor operating at high temperature.

1 . Method of converting solid combustible waste materials into highly efficient fuel, which comprises subjecting the waste materials to size reducing steps of which the last step comprises a milling operation which pulverizes the waste materials into fine particles having a high surface to mass ratio and forming a highly efficient fuel, and pneumatically feeding said fine particles into a combustion reactor operating at high temperature adapted to rapidly gasify said particles. 
   
   
       2 . Method according to  claim 1 , in which the waste materials include paper, cardboard, food, plastics, textiles and wood. 
   
   
       3 . Method according to  claim 1 , in which prior to the milling operation, mixed waste is subjected to shredding, followed by metal extraction, to produce a shredded metal-free product of a size suitable for milling into fine particles. 
   
   
       4 . Method according to  claim 1 , in which prior to the milling operation, primarily food waste is subjected to pulping, followed by water removal, to produce a pulped product having a particle size suitable for milling into fine particles. 
   
   
       5 . Method according to  claim 1 , in which primarily food waste is subjected in a size-reducing step to pulping, followed by water removal to produce a pulped product having a particle size suitable for milling into fine particles, and mixed waste is subjected in a separate size-reducing step to shredding, followed by metal extraction of any fugitive metallic materials, to produce a shredded, metal-free product of a size suitable for milling into fine particles, said pulped product and said shredded metal-free product are then intermixed and their mixture is subjected to the milling operation to produce essentially dry fine particles having a high surface to mass ratio and forming a highly efficient fuel, which particles are then directly fed into the combustion reactor. 
   
   
       6 . Method according to  claim 1 , in which the milling operation is adapted to pulverize the waste materials to a particle size of 15 μm or less in diameter. 
   
   
       7 . Apparatus for converting solid combustible waste materials into highly efficient fuel, which comprises suitable size reducing equipment ending with a mill capable of pulverizing the waste materials into fine particles having a high surface to mass ratio and forming a highly efficient fuel, and means for pneumatically transferring said fine particles directly into a combustion reactor. 
   
   
       8 . Apparatus according to  claim 7 , in which initial size reducing equipment, used prior to the mill, comprises a pulper where a slurry is formed and the size of the waste material is reduced to a particle size suitable for milling. 
   
   
       9 . Apparatus according to  claim 8 , in which the pulper is followed by a water extractor and means being provided for feeding said slurry into said water extractor in which water is removed to achieve a pulped material having a predetermined amount of solids. 
   
   
       10 . Apparatus according to  claim 7 , in which initial size reducing equipment, used prior to the mill, comprises a shredder where the size of the waste material is reduced to a degree suitable for milling into fine particles. 
   
   
       11 . Apparatus according to  claim 10 , in which the shredder is followed by a metal extractor for removing any fugitive metallic pieces and means being provided for passing shredded waste material through the metal extractor after said material exits the shredder. 
   
   
       12 . Apparatus according to  claim 7 , further comprising means for intermixing the waste materials prior to feeding them into the mill. 
   
   
       13 . Apparatus according to  claim 7 , in which the mill is adapted to mill the waste materials to form essentially dry particles of a size of about 15 μm or less in diameter. 
   
   
       14 . Apparatus according to  claim 7 , in which means are provided for injecting air into the mill so as to allow transfer of the fine particles produced in the mill by pneumatic means into a combustion reactor. 
   
   
       15 . Apparatus according to  claim 7 , in which the combustion reactor is a plasma furnace or a plasma-fired eductor of a plasma waste destruction system.