Downdraft gasifier with internal cyclonic combustion chamber

Abstract

A downdraft gasifier is disclosed. The gasifier has a biomass feeding unit, a combustion chamber, and a separator unit. The biomass feeding unit accepts raw biomass materials and selectively feeds the materials into the combustion chamber. The combustion chamber provides means to induce pyrolysis, tar cracking, and char gasification of the raw biomass materials to produce gases and ash. The separator unit accepts the gases and ash from the combustion chamber and separates the gases from the ash.

1 . A downdraft gasifier comprising:
 a biomass feeding unit;   a combustion chamber; and   a separator unit;   wherein the biomass feeding unit accepts raw biomass materials and selectively feeds the materials into the combustion chamber, the combustion chamber providing means to induce pyrolysis, tar cracking, and char gasification of the raw biomass materials to produce gases and ash, the separator unit accepting the gases and ash from the combustion chamber and separating the gases from the ash.   
     
     
         2 . The device of  claim 1 , wherein the means to induce pyrolysis, tar cracking, and char gasification comprises a biomass chamber, a tar cracking chamber, and a char gasification chamber. 
     
     
         3 . The device of  claim 2 , wherein the tar cracking chamber further comprises substantially cylindrical inner and outer walls. 
     
     
         4 . The device of  claim 3 , wherein the inner wall defines a plurality of perforations on at least a portion thereof. 
     
     
         5 . The device of  claim 4 , further comprising means for selectively closing the perforations. 
     
     
         6 . The device of  claim 2 , wherein the means to induce pyrolysis, tar cracking, and char gasification further comprises a stirrer operable to stir biomass in the combustion chamber through at least the biomass chamber and a portion of the tar cracking section. 
     
     
         7 . The device of  claim 2 , wherein the means to induce pyrolysis, tar cracking, and char gasification further comprises a heat source. 
     
     
         8 . The device of  claim 1 , wherein the separator unit comprises a cyclonic separator. 
     
     
         9 . A cyclonic combustion chamber comprising:
 a biomass chamber with a stirrer that accepts biomass material and stirs it;   a tar cracking chamber feeding from the biomass chamber, the tar cracking chamber gasifying the biomass material by pyrolysis and tar cracking of the biomass material through application of heat; and   a char gasification chamber having a grating for trapping remaining biomass material from the tar cracking chamber and holding the same during a period of char gasification.   
     
     
         10 . The cyclonic combustion chamber of  claim 9 , wherein the biomass chamber is above the tar cracking chamber, which is above the char gasification chamber, such that the biomass material is gravity fed through the combustion chamber. 
     
     
         11 . The cyclonic combustion chamber of  claim 9  further comprising an outlet conduit for removing the gasified biomass material and ash from the combustion chamber. 
     
     
         12 . The cyclonic combustion chamber of  claim 9 , wherein the tar cracking chamber further comprises inner and outer walls, the inner wall defining a plurality of perforations therein. 
     
     
         13 . The cyclonic combustion chamber of  claim 12 , wherein the plurality of perforations are selectively closable. 
     
     
         14 . A method of producing gases from biomass, the method comprising:
 heating biomass materials to induce pyrolysis;   feeding the biomass materials into a tar cracking chamber to induce tar cracking; and   feeding the biomass materials into a char gasification chamber for char gasification.   
     
     
         15 . The method of  claim 14 , wherein heating further comprises heating with fuel combustion. 
     
     
         16 . The method of  claim 14 , wherein heating further comprises heating with heated air. 
     
     
         17 . The method of  claim 14 , further comprising:
 collecting gases and ash resultant from the pyrolysis, tar cracking, and char gasification through a single conduit; and   separating the collected gases and ash.   
     
     
         18 . The method of  claim 14 , further comprising stirring the biomass through at least a portion of the pyrolysis and the tar cracking. 
     
     
         19 . The method of  claim 14 , wherein feeding the biomass materials into a tar cracking chamber and feeding the biomass materials into a char gasification chamber are accomplished via a gravity feed. 
     
     
         20 . The method of  claim 14 , wherein feeding the biomass materials into a tar cracking chamber to induce tar cracking further comprises feeding the biomass materials into a double-walled tar cracking chamber, the inner and outer wall being substantially cylindrical, and the inner wall defining a plurality of perforations sized to allow gasses to flow therethough.