Waste processing system

Abstract

Waste processing system including a shredder, a grinder and a steam explosion device such as a cooking extruder. The waste processing system is used to process raw waste, such as consumer waste, into an end product such as pellets. One potential use for these pellets is pyrolization to form biogas. Because of the uniformity composition of the processing waste (see DEFINITIONS section), imparted by the shredder and grinder, and because of the uniformity of distribution of plastic in the processing waster, imparted by the steam explosion processing, the end-product made by systems according to the present invention are superior with respect to several physical characteristics and especially well suited for pyrolization to make biogas.

1 . A waste processing system for processing a processing waste stream, the system comprising:
 a shredder adapted to shred the processing waste stream;   a grinder adapted to receive the processing waste stream after it has been shredded and to grind the processing waste stream; and   a steam explosion device adapted to receive the processing waste stream after it has been ground and to perform steam explosion processing on the processing waste stream.   
   
   
       2 . The system of  claim 1  wherein:
 the shredder is adapted to shred a processing waste stream that is at least substantially comprised of consumer waste;   the grinder is adapted to grind a processing waste stream that is at least substantially comprised of consumer waste; and   the steam explosion device is adapted to perform steam explosion processing on a processing waste stream that is at least substantially comprised of consumer waste.   
   
   
       3 . The system of  claim 1  wherein the shredder comprises at least four cutting shafts with grinding teeth. 
   
   
       4 . The system of  claim 1  wherein the shredder reduces a particle size of the waste to about 50 mm. 
   
   
       5 . The system of  claim 4  wherein the grinder reduces a particle size of the waste to about 6 mm. 
   
   
       6 . The system of  claim 1  wherein the grinder reduces a particle size of the waste to about 6 mm. 
   
   
       7 . The system of  claim 1  wherein the grinder comprises an Archimedean screw and a tube with cutting blades affixed to a wall of the tube. 
   
   
       8 . The system of  claim 1  wherein the grinder is a meat grinder type grinder and is adapted to make the ground processing waste relatively uniform in composition. 
   
   
       9 . The system of  claim 1  wherein the steam explosion device is a cooking extruder. 
   
   
       10 . The system of  claim 1  wherein the steam explosion device is adapted to generate sufficient temperature and pressure in the processing so that plastic present in the processing waste will explode. 
   
   
       11 . The system of  claim 10  wherein the steam explosion device is adapted to generate sufficient temperature and pressure in the processing so the plastic present in the processing waste will uniformly coat non-plastic fibers in the processing waste. 
   
   
       12 . The system of  claim 1  further comprising a pyrolization chamber adapted to:
 receive the processing waste stream after it has been processed by the steam explosion device;   to perform pyrolysis on the processing waste stream; and   to produce biogas through the pyrolysis.   
   
   
       13 . The system of  claim 12  wherein the pyrolization chamber is located remotely from the steam explosion device. 
   
   
       14 . The system of  claim 1  further comprising a shape former device adapted to receive the processing waste stream after it has undergone steam explosion processing in the steam explosion device and to form it into a plurality of discrete, solid pieces. 
   
   
       15 . The system of  claim 14  wherein the shape former device is a pelletizer and the plurality of discrete, solid pieces are pellets. 
   
   
       16 . A waste processing system for processing a processing waste stream, the system comprising a steam explosion device comprising:
 an extrusion chamber adapted to raise the temperature and pressure of the processing waste;   a steam introduction device adapted to introduce steam into the extrusion chamber; and   a steam explosion chamber which is located and adapted to receive processing waste form the extrusion chamber and which is maintained at a sufficiently lower pressure than the extrusion chamber so that explosions will occur throughout the processing waste after it passes into the steam explosion chamber.   
   
   
       17 . The system of  claim 16  further comprising:
 a shredder adapted to shred the processing waste stream; and   a grinder adapted to receive the processing waste stream after it has been shredded and to grind the processing waste stream;   
   
   
       18 . The system of  claim 17  wherein:
 the shredder is adapted to shred a processing waste stream that is at least substantially comprised of consumer waste;   the grinder is adapted to grind a processing waste stream that is at least substantially comprised of consumer waste; and   the steam explosion device is adapted to perform steam explosion processing on a processing waste stream that is at least substantially comprised of consumer waste.   
   
   
       19 . A waste processing system for processing a processing waste stream, the system comprising a steam explosion device comprising:
 an extrusion chamber adapted to raise the temperature and pressure of the processing waste;   a narrowing conduit located in the extrusion chamber and shaped to build up backpressure in the processing waste as processing waste passes from a wide end of the narrowing conduit to a narrowing end of the narrowing conduit; and   a steam explosion chamber which is located and adapted to receive processing waste form the extrusion chamber and which is maintained at a sufficiently lower pressure than the extrusion chamber so that explosions will occur throughout the processing waste after it passes into the steam explosion chamber.   
   
   
       20 . The system of  claim 17  wherein the narrowing conduit is in the form of an inverted cone.