Waste treatment apparatus and method

Abstract

Waste is treated by pyrolysis at a temperature of from 400-700° C. and combustion at a temperature of at least 400° C. Off-gases are catalytically oxidized to reduce emissions. The combusting waste is periodically agitated with high-pressure air bursts to disrupt waste in the chamber and promote even and complete combustion. Air is introduced during pyrolysis to promote controlled flow of off-gas to the catalyst and air and/or water is used to dislodge accumulated ash at the end of the treatment process.

1 - 36 . (canceled) 
     
     
         37 . A process for waste treatment comprising:
 introducing waste into a chamber;   heating the waste to an elevated temperature to effect pyrolysis of the waste;   introducing oxygen into the chamber to effect combustion of the waste;   agitating the waste with gas to promote combustion; and   removing combusted waste from the chamber.   
     
     
         38 . The process of  claim 37 , wherein agitating the waste comprises introducing gas at high pressure into the chamber so as to agitate the waste during combustion. 
     
     
         39 . The process of  claim 37 , comprising repeatedly agitating the waste in the chamber so as to promote combustion of the waste. 
     
     
         40 . The process of  claim 37 , comprising agitating the waste at a frequency from at least once every 20 seconds to at least once every 5 minutes. 
     
     
         41 . The process of  claim 37 , wherein the gas for agitating the waste comprises air. 
     
     
         42 . The process of  claim 37 , wherein agitating the waste comprises introducing the gas for agitating the waste into the chamber at a pressure of 3 atmospheres or greater. 
     
     
         43 . The process of  claim 42 , wherein the gas for agitating the waste is at a pressure of 5 atmospheres or greater. 
     
     
         44 . Apparatus for waste treatment, comprising:
 a sealable chamber;   a waste treatment zone in the chamber;   a port for introducing waste into the chamber;   a port for the exit of treated waste from the chamber;   a heating element;   one or more air inlets in a wall of the chamber;   a high pressure air source; and   one or more conduits to connect the air inlets to the source of air at high pressure.   
     
     
         45 . The apparatus of  claim 44 , wherein the one or more air inlets are in the form of nozzles located in a lower portion of the chamber at least half way down the wall or in the bottom of the chamber. 
     
     
         46 . The apparatus of  claim 44 , wherein the one or more air inlets are adapted in use to direct air at high pressure towards combusting material located towards the bottom of the chamber. 
     
     
         47 . The apparatus of  claim 44 , comprising a control unit adapted to introduce air into the chamber periodically via the one or more air inlets. 
     
     
         48 . The apparatus of  claim 44 , wherein in use air is introduced into the chamber at a pressure of at least 3 atmospheres. 
     
     
         49 . The apparatus of  claim 48 , wherein in use air is introduced into the chamber at a pressure of at least 5 atmospheres. 
     
     
         50 . A process for waste treatment, comprising:
 introducing waste into a chamber;   heating the waste to an elevated temperature to effect pyrolysis of the waste, wherein pyrolysis of the waste generates off-gases, and wherein the process comprises;   introducing a small amount of air into the chamber during pyrolysis;   introducing oxygen into the chamber to effect combustion of the waste; and   removing combusted waste from the chamber.   
     
     
         51 . The process of  claim 50 , comprising introducing air into the chamber during pyrolysis in an amount sufficient to promote smooth flow of off-gas from the chamber but sufficiently small that the pyrolysis remains endothermic. 
     
     
         52 . The process of  claim 50 , comprising introducing air at a rate of up to 10 litres per minute per kg of waste. 
     
     
         53 . A process for waste treatment, comprising:
 introducing waste into a chamber;   heating the waste to an elevated temperature to effect pyrolysis of the waste;   introducing oxygen into the chamber to effect combustion of the waste;   removing combusted waste from the chamber; and   agitating accumulated ash produced by the combustion so as to dislodge the accumulated ash and urge it towards an exit of the chamber.   
     
     
         54 . The process of  claim 53 , comprising agitating the accumulated ash by injecting air into the chamber towards the accumulated ash. 
     
     
         55 . The process of  claim 53 , comprising agitating the ash by injecting water into the chamber towards the ash. 
     
     
         56 . The process of  claim 55 , wherein the water is steam. 
     
     
         57 . The apparatus of  claim 44 , comprising:
 a sealable chamber;   a waste treatment zone in the chamber;   a port for introduction of waste into the chamber;   a port for exit of treated waste;   a heating element; and   one or more inlets located in a wall or floor of the chamber, said one or more inlets connected to an air supply via control equipment such that each of the one or more inlets can independently be used to introduce air into the chamber, and wherein the control equipment is programmed to operate in at least two of the following modes:
 (i) air is introduced into the chamber during pyrolysis of waste in the chamber to dilute off-gas exiting the chamber; 
 (ii) air is introduced into the chamber in bursts during combustion of waste in the chamber to promote combustion of the waste; and 
 (iii) air is introduced into the chamber during combustion to dislodge accumulated ash. 
   
     
     
         58 . The apparatus of  claim 57 , wherein the control equipment is programmed to operate in at least three of modes (i) to (iii). 
     
     
         59 . The apparatus of  claim 57 , wherein said one or more inlets are connected to an air supply and to a water supply via the control equipment such that each of the one or more inlets can independently be used to introduce air or water into the chamber, and wherein the control equipment is also programmed to operate in a mode (iv) wherein water is introduced into the chamber during combustion to dislodge accumulated ash. 
     
     
         60 . The process for waste treatment comprising
 introducing waste into a chamber;   heating the waste to an elevated temperature to effect pyrolysis of the waste, wherein pyrolysis of the waste generates off-gases;   introducing oxygen into the chamber to effect combustion of the waste;   introducing a small amount of air into the chamber during pyrolysis;   agitating the waste with gas to promote combustion;   agitating accumulated ash produced by the combustion so as to dislodge the accumulated ash and urge it towards an exit of the chamber; and   removing combusted waste from the chamber.   
     
     
         61 . A process for waste treatment, comprising:
 introducing waste into a chamber;   heating the waste to an elevated temperature to effect pyrolysis of the waste;   introducing oxygen into the chamber to effect combustion of the waste; and   removing combusted waste from the chamber, wherein pyrolysis of the waste generates off-gases which are passed through a catalyst to remove one or more noxious components thereof, and wherein the off-gases are filtered using an inertial separator prior to contact of the off-gases with the catalyst.   
     
     
         62 . An apparatus for waste treatment, comprising:
 a sealable chamber;   a waste treatment zone in the chamber;   a port for introducing waste into the chamber;   a port for the exit of treated waste;   a heating element,   a catalyst; and   an inertial separator between the chamber and the catalyst.