Method and apparatus for plasma gasification of waste materials

Abstract

A method and apparatus for plasma gasification of waste materials consisting of organic and inorganic portions is provided which includes a refractory-lined reactor vessel, a feeder mechanism, and a DC electrode device. The refractory-lined reactor vessel has a processing chamber formed therein. The feeder mechanism feeds continuously waste materials into the processing chamber at a controlled feed rate. The DC electrode device is used for heating the processing chamber to a sufficient temperature so as to convert the organic portions of the waste materials to a synthetic gas consisting of hydrogen and carbon monoxide and to a carbon particulate, and to convert the inorganic portions of the waste materials to a molten material consisting of a lower metallic layer and a slag layer formed on top of the metallic layer.

1 . An apparatus for plasma gasification of waste materials consisting of organic and inorganic portions comprising: 
 a refractory-lined reactor vessel having a processing chamber formed therein;    feeder means for feeding continuously waste materials into said processing chamber at a controlled feed rate;    DC electrode means for heating said processing chamber to a sufficient temperature so as to convert the organic portions of the waste materials to a synthetic gas consisting of hydrogen and carbon monoxide and to a carbon particulate, and to convert the inorganic portions of the waste materials to a molten material consisting of a lower metallic layer and a slag layer formed on top of the metallic layer;    means for withdrawing said synthetic gas from the processing chamber as an off-gas;    gas pipe means formed with a refractory lining for maintaining said off-gas at an effective temperature to substantially prevent the formation of complex organic components;    means for removing said molten material from said processing chamber;    gas sampler monitoring means for monitoring the amount of carbon particulate entrained in the off-gas;    means for injecting an oxidant into said processing chamber in predetermined amounts so as to convert a majority of said carbon particulate into carbon monoxide;    control means responsive to said monitoring means for regulating the amount of oxidant being injected into said processing chamber so as to minimize the formation of carbon particulate; and    means for cooling rapidly the off-gas to a temperature of less than about 150 degrees C. and for separating the carbon particulate from the cooled off-gas to form a product clean gas.    
   
   
       2 . An apparatus for plasma gasification of waste materials as claimed in  claim 1 , wherein said DC electrode means includes a pair of spaced-apart top graphite anode electrodes extending downwardly from a top end of said reactor vessel and their lower ends thereof being submerged in said molten material, and a conductive plate defining a cathode electrode formed as a portion of a bottom of said reactor vessel and being disposed opposite to said anode electrodes.  
   
   
       3 . An apparatus for plasma gasification of waste materials as claimed in  claim 1 , wherein said DC electrode means includes a pair of spaced-apart top graphite anode electrodes extending downwardly from a top end of said reactor vessel and their lower ends thereof being submerged in said molten material, and a bottom of said reactor vessel being made of a conductive material so as to function as a cathode electrode.  
   
   
       4 . An apparatus for plasma gasification of waste materials as claimed in  claim 1 , wherein said feeder means includes a first feeder mechanism for feeding said waste materials directly into the slag layer of the molten material by way of a first extrusion feeder tube formed in a circumferential side wall of said reactor vessel and into an area between said top graphite anode electrodes forming the hottest part of the processing chamber.  
   
   
       5 . An apparatus for plasma gasification of waste materials as claimed in  claim 4 , wherein said feeder means further includes a second feeder mechanism for feeding said waste materials directly into the slag layer of the molten material by way of a second extrusion feeder tube formed in the circumferential side wall of said reactor vessel and opposite to said first extrusion feeder tube.  
   
   
       6 . An apparatus for plasma gasification of waste materials as claimed in  claim 4 , wherein said feeder means further includes a second feeder mechanism for feeding said waste materials directly into the slag layer of the molten material by way of a second extrusion feeder tube formed in a circumferential side wall of said reactor vessel and adjacent to said first extrusion feeder tube.  
   
   
       7 . An apparatus for plasma gasification of waste materials as claimed in  claim 1 , wherein said DC electrode means includes at least one top graphite anode electrode extending downwardly from a top end of said reactor vessel and its lower end thereof being submerged in said molten material, and a conductive plate defining a cathode electrode formed as a portion of a bottom of said reactor vessel and being disposed opposite to said at least one anode electrode.  
   
   
       8 . An apparatus for plasma gasification of waste materials as claimed in  claim 7 , wherein said feeder means includes first and second feeder mechanisms disposed on opposite sides of said at least one top anode electrode for feeding waste materials directly into the slag layer of the molten material by way of respective first and second extrusion feeder tubes formed on opposite sides of a circumferential side wall of said reactor vessel.  
   
   
       9 . An apparatus for plasma gasification of waste materials as claimed in  claim 7 , wherein said feeder means includes first and second feeder mechanisms disposed on opposite sides of said at least one top anode electrode for feeding waste materials directly into the slag layer of the molten material by way of respective first and second extrusion feeder tubes formed adjacent to each other on a circumferential side wall of said reactor vessel.  
   
   
       10 . An apparatus for plasma gasification of waste materials consisting of organic and inorganic portions comprising: 
 a refractory-lined reactor vessel having a processing chamber formed therein;    feeder means for feeding continuously waste materials into said processing chamber at a controlled feed rate; and    DC electrode means for heating said processing chamber to a sufficient temperature so as to convert the organic portions of the waste materials to a synthetic gas consisting of hydrogen and carbon monoxide and to a carbon particulate, and to convert the inorganic portions of the waste materials to a molten material consisting of a lower metallic layer and a slag layer formed on top of the metallic layer.    
   
   
       11 . An apparatus for plasma gasification of waste materials as claimed in  claim 10 , wherein said DC electrode means includes a pair of spaced-apart top graphite anode electrodes extending downwardly from a top end of said reactor vessel and their lower ends thereof being submerged in said molten material, and a conductive plate defining a cathode electrode formed as a portion of a bottom of said reactor vessel and being disposed opposite to a corresponding one of said anode electrodes.  
   
   
       12 . An apparatus for plasma gasification of waste materials as claimed in  claim 10 , wherein said DC electrode means includes a pair of spaced-apart top graphite anode electrodes extending downwardly from a top end of said reactor vessel and their lower ends thereof being submerged in said molten material, and a bottom of said reactor vessel being made of a conductive material so as to function as a cathode electrode.  
   
   
       13 . An apparatus for plasma gasification of waste materials as claimed in  claim 11 , wherein said feeder means includes a first feeder mechanism for feeding said waste materials directly into the slag layer of the molten material by way of a first extrusion feeder tube formed in a circumferential side wall of said reactor vessel and into an area between said top graphite anode electrodes forming the hottest part of the processing chamber.  
   
   
       14 . An apparatus for plasma gasification of waste materials as claimed in  claim 13 , wherein said feeder means further includes a second feeder mechanism for feeding said waste materials directly into the slag layer of the molten material by way of a second extrusion feeder tube formed in the circumferential side wall of said reactor vessel and opposite to said first extrusion feeder tube.  
   
   
       15 . An apparatus for plasma gasification of waste materials as claimed in  claim 13 , wherein said feeder means further includes a second feeder mechanism for feeding said waste materials directly into the slag layer of the molten material by way of a second extrusion feeder tube formed in a circumferential side wall of said reactor vessel and adjacent to said first extrusion feeder tube.  
   
   
       16 . An apparatus for plasma gasification of waste materials as claimed in  claim 10 , wherein said DC electrode means includes at least one top graphite anode electrode extending downwardly from a top end of said reactor vessel and its lower end thereof being submerged in said molten material, and a conductive plate defining a cathode electrode formed as a portion of a bottom of said reactor vessel and being disposed opposite to said at least one anode electrode.  
   
   
       17 . An apparatus for plasma gasification of waste materials as claimed in  claim 16 , wherein said feeder means includes first and second feeder mechanisms disposed on opposite sides of said at least one top anode electrode for feeding waste materials directly into the slag layer of the molten material by way of respective first and second extrusion feeder tubes formed on opposite sides of a circumferential side wall of said reactor vessel.  
   
   
       18 . An apparatus for plasma gasification of waste materials as claimed in  claim 16 , wherein said feeder means includes first and second feeder mechanisms disposed on opposite sides of said at least one top anode electrode for feeding waste materials directly into the slag layer of the molten material by way of respective first and second extrusion feeder tubes formed adjacent to each other on a circumferential side wall of said reactor vessel.  
   
   
       19 . A method for plasma gasification of waste materials consisting of organic and inorganic portions comprising the steps of: 
 providing a refractory-lined reactor vessel having a processing chamber formed therein;    feeding continuously waste materials into said processing chamber at a controlled feed rate;    heating said waste materials in said processing chamber using a DC electrode device so as to convert the organic portions of the waste materials to a synthetic gas consisting of hydrogen and carbon monoxide and to a carbon particulate, and to convert the inorganic portions of the waste materials to a molten material consisting of a lower metallic layer and a slag layer formed on top of the metallic layer;    withdrawing said synthetic gas from the processing chamber as an off-gas through a gas pipe formed with a refractory lining to maintain said off-gas at an effective temperature to substantially prevent the formation of complex organic components;    removing said molten material from said processing chamber;    monitoring the amount of carbon particulate entrained in the off-gas using a gas sampler monitor;    injecting an oxidant into said processing chamber in predetermined amounts so as to convert a majority of said carbon particulate into carbon monoxide;    regulating the amount of oxidant being injected into said processing chamber in response to the gas sampler monitor so as to minimize the formation of carbon particulate;    cooling rapidly the off-gas using a heat exchanger to a temperature of less than about 150 degrees C.; and    separating the carbon particulate from the cooled off-gas to form a product clean gas.    
   
   
       20 . A method for plasma gasification of waste materials as claimed in  claim 19 , wherein said step of feeding includes feeding through first and second feeder mechanisms disposed on opposite sides of said DC electrode device for feeding waste materials directly into the slag layer of the molten material by way of respective first and second extrusion feeder tubes formed on opposite sides of a circumferential side wall of said reactor vessel.