Microwave-based pyrolysis reactor and associated methods

Abstract

A method for processing waste using pyrolysis reactor include generating a microwave signal; amplifying the microwave signal into a plurality of drive signals; measuring temperature of the waste; determining, based on measured temperature, at least one phase-control signal; and outputting the at least one phase-control signal to maximize power transfer to the waste.

1 . A pyrolysis reactor, comprising:
 a microwave cavity configured to contain a waste mixture within an internal space; and   a plurality of probes that couple a corresponding plurality of drive signals into the microwave cavity to excite a plurality of cavity modes and heat the waste mixture.   
     
     
         2 . The pyrolysis reactor of  claim 1 , the microwave cavity having walls shaped as a cylindrical shell surrounding the internal space. 
     
     
         3 . The pyrolysis reactor of  claim 2 , further comprising a linear electrical conductor surrounded by the cylindrical shell. 
     
     
         4 . The pyrolysis reactor of  claim 3 , wherein the linear electrical conductor is a spindle for an auger located at least partially within the internal space, to stir the waste mixture. 
     
     
         5 . The pyrolysis reactor of  claim 1 , further comprising thermal insulation surrounding the microwave cavity. 
     
     
         6 . The pyrolysis reactor of  claim 5 , further comprising a heat shield between the microwave cavity and the thermal insulation. 
     
     
         7 . The pyrolysis reactor of  claim 1 , further comprising at least one frequency selective surface disposed in front of at least a part of the microwave cavity and in the internal space, to surround the waste mixture. 
     
     
         8 . The pyrolysis reactor of  claim 1 , further comprising:
 an oscillator for generating a microwave signal;   a plurality of solid-state power amplifiers for amplifying the microwave signal into the plurality of drive signals; and   one or more variable phase shifters electrically connected to the oscillator, each of the variable phase shifters being configured to phase-shift one of the microwave signals prior to amplification in a corresponding one of the plurality of solid-state power amplifiers.   
     
     
         9 . The pyrolysis reactor of  claim 8 , further comprising:
 a plurality of sensors for measuring temperatures of the waste mixture; and   a processing unit configured to (i) determine, based on measured temperatures, one or more phase-control signals and (ii) output the phase-control signals to the one or more phase-shifters to maximize power transfer to the waste mixture.   
     
     
         10 . The pyrolysis reactor of  claim 9 , the plurality of sensors comprising:
 a plurality of thermocouples; and   an infrared camera for recording a thermal image stream of the waste mixture.   
     
     
         11 . The pyrolysis reactor of  claim 9 , the plurality of sensors comprising one or more microwave radiometers for measuring thermally-emitted electromagnetic radiation from the waste mixture. 
     
     
         12 . A method for processing a waste mixture, comprising:
 coupling a plurality of drive signals into a microwave cavity to excite a plurality of cavity modes, the microwave cavity containing the waste mixture; and   phase-shifting, based on a temperature of the waste mixture, one or more of the plurality of drive signals.   
     
     
         13 . The method of  claim 12 , further comprising:
 generating a microwave signal with an oscillator;   splitting the microwave signal into the plurality of drive signals; and   amplifying each of the plurality of drive signals into a corresponding one of a plurality of amplified signals;   wherein:
 said coupling includes coupling the plurality of amplified signals into the microwave cavity; and 
 said phase-shifting occurs prior to said amplifying. 
   
     
     
         14 . The method of  claim 12 , further comprising measuring the temperature of the waste mixture with a thermocouple. 
     
     
         15 . The method of  claim 12 , further comprising recording a thermal image stream of the waste mixture using an infrared camera. 
     
     
         16 . The method of  claim 12 , further comprising measuring thermally-emitted electromagnetic radiation from the waste mixture using a microwave radiometer. 
     
     
         17 . The method of  claim 12 , further comprising stirring the waste mixture with an auger. 
     
     
         18 . The method of  claim 12 , further comprising adding one or more additives to the waste mixture to increase thermal conductivity of the waste mixture. 
     
     
         19 . A system for processing a waste mixture, comprising:
 a microwave power generator;   a pyrolysis reactor having a plurality of microwave probes connected to the microwave power generator and configured to drive electromagnetic energy that heats the waste mixture inside the pyrolysis reactor and produce bio-oil; and   a bio-oil upgrade element for producing a liquid fuel from the bio-oil.   
     
     
         20 . The system of  claim 19 , further comprising an electric generator for at least partially powering the microwave power generator using the liquid fuel.