Waste energy conversion system

Abstract

An on-site modular method and system for processing waste typically including food from a food services facility. The waste is processed in a size reduction unit and subsequently dried in a dryer. The dried shredded waste is processed to produce densified pellets. The food binds the non-food waste in the pellets. The pellets are burned in a thermal conversion unit to produce a gas and waste heat. The waste heat is directed to the dryer for use therein. The gas is fed to a generator or turbine to produce electricity. A portion of the electricity produced is used to energize the process.

1 . An on-site method of processing RDF waste including food from a food services facility, the method comprising:
 shredding the waste in a shredder;   drying the shredded waste in a dryer;   using a pelletizer to pelletize the dried shredded waste wherein the food binds the non-food waste in the pellets;   burning the pellets in a gasifier to produce a flammable fuel gas and waste heat;   directing the waste heat to the dryer for use therein to dry the shredded waste;   combusting the gas in a generator to produce electricity; and   using a portion of the electricity produced to energize the shredder, the dryer, the pelletizer, and the gasifier.   
   
   
       2 . The method of  claim 1  wherein the pelletizer includes a pre-compaction auger and the method further includes pre-compacting the dried shredded waste prior to pelletizing. 
   
   
       3 . The method of  claim 1  in which the shredder, the dryer, the pelletizer, the gasifier, and the generator are linked together in a modular unit transported to the food services facility. 
   
   
       4 . The method of  claim 1  in which a portion of the generated electricity is used to energize loads of the food services facility. 
   
   
       5 . The method of  claim 1  in which a portion of the generated electricity is sold. 
   
   
       6 . The method of  claim 1  in which the shredder is configured to shred the waste into pieces with a maximum dimension of between ⅜″ and ½″. 
   
   
       7 . The method of  claim 1  in which the shredded waste is dried to a moisture content of between 12-15 percent. 
   
   
       8 . The method of  claim 1  in which the pellets are between ⅛ and ½ inches in diameter and between ¼ and ⅝ inches long. 
   
   
       9 . An on-site food services facility waste processing system comprising:
 a generator configured to burn gas to produce electricity;   a gasifier producing gas for the generator and waste heat;   a shredder powered by the generator for shredding the waste including food from the food services facility;   a dryer powered by the generator which uses the gasifier waste heat to dry the shredded waste; and   a pelletizer powered by the generator for producing pellets of the dried shredded waste with the food binding the non-food waste, the pellets burned in the gasifier to produce gas as a fuel for the generator.   
   
   
       10 . The system of  claim 9  wherein the pelletizer includes a pre-compaction auger for pre-compacting the dried shredded waste prior to pelletizing. 
   
   
       11 . The system of  claim 9  in which the shredder, the dryer, the pelletizer, the gasifier, and the generator are housed in a modular unit transportable to the food services facility. 
   
   
       12 . An on-site method of processing waste from a facility, the method comprising:
 feeding the waste to a shredder on-site at the facility;   drying the shredded waste in a dryer;   using a pelletizer to pelletize the dried shredded waste;   burning the pellets in a gasifier to produce a gas and waste heat;   directing the waste heat to the dryer for use therein to dry the shredded waste;   combusting the gas in a generator to produce electricity; and   using a portion of the produced electricity to energize at least one of the shredder, the dryer, the pelletizer, and the gasifier.   
   
   
       13 . An on-site facility waste processing system comprising:
 an on-site generator configured to burn gas to produce electricity;   an on-site gasifier producing gas for the generator and waste heat;   an on-site shredder powered by the generator for shredding the waste from the facility;   a dryer which uses the gasifier waste heat to dry the shredded waste; and   a pelletizer for producing pellets of the dried shredded waste burned in the gasifier to produce gas as a fuel used by the generator.   
   
   
       14 . An on-site method of processing waste including food from a food services facility, the method comprising:
 shredding the waste in a shredder on-site at the facility;   drying the shredded waste in a dryer on-site at the facility; and   using a pelletizer on-site at the facility to pelletize the dried shredded waste wherein the food binds the non-food waste in the pellets.   
   
   
       15 . The method of  claim 14  further including:
 burning the pellets in a gasifier to produce a gas and waste heat,   directing the waste heat to the dryer for use therein to dry the shredded waste,   combusting the gas in a generator to produce electricity, and   using a portion of the produced electricity to energize the shredder, the dryer, the pelletizer, and the gasifier.   
   
   
       16 . An on-site food services facility waste processing system comprising:
 an on-site shredder for shredding waste including food from the food services facility;   an on-site dryer which uses heat to dry the shredded waste; and   an on-site pelletizer for producing pellets of the dried shredded waste with the food binding the non-food waste.   
   
   
       17 . The system of  claim 16  further including:
 a generator configured to combust gas to produce electricity, and   a gasifier which burns the pellets producing gas for the generator and waste heat.   
   
   
       18 . The system of  claim 17  in which the shredder, dryer, and pelletizer are powered by the generator. 
   
   
       19 . The system of  claim 17  in which the gasifier waste heat is directed to the dryer for drying the shredded waste. 
   
   
       20 . An on-site method of processing waste from a facility, the method comprising:
 shredding the waste in a shredder;   drying the shredded waste in a dryer;   using a densifier to densify the dried shredded waste;   burning the densified waste to produce gas and waste heat;   directing the waste heat to the dryer for use therein to dry the shredded waste;   using the gas to produce electricity; and   using a portion of the electricity to energize at least one of the shredder, the dryer, the pelletizer, and the gasifier.   
   
   
       21 . The method of  claim 20  wherein the densifier includes a pelletizer with a pre-compaction auger and the method further includes pre-compacting the dried shredded waste prior to pelletizing. 
   
   
       22 . An on-site facility waste processing system comprising:
 a shredder for shredding waste from the food services facility;   a dryer for drying the shredded waste;   a densifier for densifying the dried shredded waste; and   means for burning the densified waste to produce electricity used by at least one of the shredder, the dryer, and the densifier.   
   
   
       23 . An on-site method of processing waste from a facility, the method comprising:
 reducing the size of the waste on-site at the facility;   drying the waste in a dryer;   densifying the dried waste;   thermally converting the densified waste to produce a gas and waste heat;   using the waste heat to dry the shredded waste;   combusting the gas to produce electricity; and   using a portion of the produced electricity for the size reduction, drying, and/or densification processes.