Waste treatment method and apparatus

Abstract

A waste treatment plant ( 1 ) comprises an incinerator unit ( 30 ) and an autoclave unit ( 9 ) and operates such that steam for the autoclave is generated from heat in the incinerator and contaminated water from the autoclave is used to control the temperature in the incinerator, the contamination being destroyed in the process. Exhaust gas from the incinerator is used to reduce the water content of waste treated in the autoclave. Steam generated by the incinerator is available for plant washing operations, to wash bins that supplied waste to the plant before the bins are returned.

1 . A waste disposal treatment apparatus, comprising:
 an incinerator, for incineration of waste, comprising a steam generator;   an autoclave, for steam treatment of waste;   a conduit to supply steam from the steam generator in the incinerator to the autoclave; and   a conduit for transfer of water from the autoclave to a combustion chamber in the incinerator.   
   
   
       2 . The apparatus of  claim 1 , comprising a water storage unit, a conduit for transfer of water from the autoclave to the storage unit and a conduit for transfer of water from the storage unit to the combustion chamber. 
   
   
       3 . The apparatus of  claim 1 , comprising a drier, for drying of steam-treated waste which exits the autoclave and a conduit to supply heat from the incinerator to the drier. 
   
   
       4 . The apparatus of  claim 1 , comprising a drier, for drying of steam-treated waste which exits the autoclave and a conduit to supply exhaust from the incinerator or steam from the steam generator to the drier. 
   
   
       5 . The apparatus of  claim 1 , comprising a feeder for feeding waste to an entry port located on an upper portion of the autoclave. 
   
   
       6 . The apparatus of  claim 5 , wherein the entry port is at the top of the autoclave. 
   
   
       7 . The apparatus of  claim 1 , wherein the autoclave comprises an exit port located on a lower portion of the autoclave chamber. 
   
   
       8 . The apparatus of  claim 7 , wherein when the exit port is open waste in the autoclave exits through the exit port via gravity. 
   
   
       9 . The apparatus of  claim 1 , wherein the ratio of waste treatment capacity per unit time of the incinerator to the waste treatment capacity per unit time of the autoclave is from 1:7 to 5:7. 
   
   
       10 . The apparatus of  claim 9 , wherein the ratio is from 2:7 to 4:7. 
   
   
       11 . The apparatus of  claim 1 , further comprising a second steam generator, not powered by the incinerator, and a conduit for transfer of steam from the second steam generator to the autoclave. 
   
   
       12 . The apparatus of  claim 11 , further comprising control equipment to turn on the second steam generator, which is optionally oil-, gas- or electrically-powered, in the event of failure or inadequate operation of the steam generator in the incinerator. 
   
   
       13 . The apparatus of  claim 1 , comprising a steam line from the steam generator to supply steam for cleaning of equipment that is part of or associated with the autoclave, for example, bins used to deliver waste to the autoclave. 
   
   
       14 . The apparatus of  claim 1 , wherein the autoclave comprises a feed chute and an exit chute and wherein the apparatus comprises a feeder to feed waste to the feed chute, the feed chute being located higher than the autoclave, whereby waste is fed from the feed chute to the autoclave by gravity, the exit chute is located below the autoclave and waste exiting the autoclave is fed to the exit chute by gravity. 
   
   
       15 . The apparatus of  claim 1 , comprising a shredder upstream of the autoclave. 
   
   
       16 . The apparatus of  claim 15  wherein shredded waste exiting the shredder is gravity-fed to the autoclave. 
   
   
       17 . The apparatus of  claim 1 , wherein the autoclave comprises a level detector, to detect the level of waste in the autoclave and a vibrator to vibrate waste inside the autoclave chamber so as to redistribute waste within the chamber. 
   
   
       18 . The apparatus of  claim 17 , comprising control equipment associated with the level detector which operates to activate the vibrator when waste within the chamber is above a predetermined level. 
   
   
       19 . The apparatus of  claim 18 , wherein the control equipment also operates to deactivate the vibrator, when after activation for a predetermined period of time, the level of waste within the chamber has not dropped below the predetermined level. 
   
   
       20 . The apparatus of  claim 1 , comprising a metal detector to detect metal in waste upstream of the autoclave. 
   
   
       21 . The apparatus of  claim 20 , wherein the metal detector is upstream of the shredder. 
   
   
       22 . The apparatus of  claim 20 , comprising control equipment adapted to divert waste which contains metal to the incinerator. 
   
   
       23 . The apparatus of  claim 1 , comprising a weighing station and control equipment which operates so as to weigh a bin containing waste both before and after the bin is emptied and to identify a bin which, after having been emptied, weighs more than a predetermined amount. 
   
   
       24 . The apparatus of  claim 23 , wherein the weighing station is incorporated into a feeder, so that a bin can be weighed whilst it is being lifted into position for feeding of its contents to the autoclave. 
   
   
       25 . The apparatus of  claim 1 , comprising the incinerator in a first waste processing stream and the autoclave in a second, parallel stream. 
   
   
       26 . The apparatus of  claim 1 , comprising a bin washing unit and a conduit for transfer of water used for washing to the water storage unit. 
   
   
       27 . The apparatus of  claim 1 , wherein the autoclave comprises slide valves, which open to allow waste into the autoclave and to allow treated waste to exit and which close to seal the autoclave. 
   
   
       28 . The apparatus of  claim 1 , comprising control equipment associated with a slide valve at an entry port of the autoclave and adapted to close the slide valve when the autoclave is full of waste. 
   
   
       29 . A method of waste treatment, comprising simultaneously:
 incinerating a first waste stream in an incinerator;   using heat from the incinerator to generate steam;   passing the steam to an autoclave; and   steam-treating a second waste stream in the autoclave, and   transferring water from the autoclave into a combustion chamber of the incinerator.   
   
   
       30 . The method of  claim 29 , comprising transferring water from the autoclave to a store and transferring water, when required, from the store to the combustion chamber. 
   
   
       31 . The method of  claim 29  comprising using heat from the incinerator to reduce the water content of waste which has been steam-treated in the autoclave. 
   
   
       32 . The method of  claim 31 , wherein waste steam-treated in the autoclave is transferred to an air drier, wherein the air drier is supplied with hot exhaust from the incinerator. 
   
   
       33 . The method of  claim 29 , comprising feeding the second waste stream into the top of a chamber in the autoclave, accumulating waste in the chamber and vibrating the chamber so as to redistribute the accumulated waste within the chamber. 
   
   
       34 . The method of  claim 29 , comprising opening an exit port at the bottom of the autoclave chamber and feeding the steam-treated waste out of the chamber by gravity. 
   
   
       35 . The method of  claim 24 , comprising shredding the waste stream before it is steam-treated. 
   
   
       36 . The method of  claim 29 , wherein the ratio of the waste treatment per unit time of the incinerator to the waste treatment per unit time of the autoclave is from 1:7 to 5:7. 
   
   
       37 . The method of  claim 36  wherein the ratio is from 2:7 to 4:7. 
   
   
       38 - 39 . (canceled)