US 2003/0228196 A1Published application

Thermal remediation process

AssigneeHood Environmental Engineering, Ltd.

InventorsRobert Merton Satchwell, Roderick Michael Facey

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Abstract

A process and apparatus are provided for removing organic and inorganic contaminants from solid media such as drill cuttings, tank bottoms or contaminated soils. The process is conducted in at least one thermal screw conveyor which provides two or more separate temperature zones which can be operated as one or more of low temperature thermal desorption, high temperature thermal desorption and pyrolysis. Preferably the process is conducted in three interconnected thermal screw conveyors which each provide a separate temperature zone. The process is conducted such that the solid media in each of the temperature zones is held under a vacuum. Direct and indirect heating of the solid media in each of the temperature zones is provided. In the pyrolysis zone, an organic binder may be added to encapsulate inorganic contaminants such as metals.

Claims41

Dependent claims

A method of thermal remediation of contaminated solid media, comprising:

providing a vacuum housing equipped with at least one hollow shafted screw conveyor having a plurality of openings along its length, said vacuum housing providing two or more separate temperature zones along its length such that the temperature of each successive temperature zone can be maintained at a temperature which is equal to or greater than that of the previous temperature zone;
indirectly and separately heating the two or more temperature zones to temperatures sufficient to volatilize one or more of the contaminants in the contaminated solid media;
feeding the contaminated solid media into the at least one screw conveyor and conveying the contaminated solid media through the vacuum housing with mixing by rotating the at least one screw conveyor;
injecting a hot, inert, non-condensible gas through the plurality of openings in the at least one screw conveyor to directly heat the contaminated solid media in each of the temperature zones to temperatures sufficient to volatilize one or more of the contaminants in the contaminated solid media;
withdrawing the volatilized contaminants and the hot, inert, non-condensible gas from the at least one screw conveyor while holding the contaminated solid media under a vacuum;
maintaining the vacuum on the contaminated solid media;
separating the volatilized contaminants from the non-condensible gas;
and
discharging from the vacuum housing solid media reduced in contaminants.

6 more elements

An apparatus for thermal remediation of contaminated solid media, comprising:

a vacuum housing equipped with at least one hollow shafted screw conveyor adapted to move the contaminated solid media along the length of the vacuum housing, said screw conveyor being formed with a plurality of openings along its length sufficient to introduce a gas, said vacuum housing being partitioned to form two or more separate temperature zones along its length such that the temperature of each successive temperature zone can be maintained at a temperature which is equal to or greater than that of the previous temperature zone;
means for feeding the contaminated solid media into the at least one screw conveyor;
means for rotating the at least one screw conveyor so as to convey the contaminated solid media along its length;
means for indirectly heating the two or more temperature zones to temperatures sufficient to volatilize one or more of the contaminants in the solid contaminated media;
means for injecting a hot, inert, non-condensible gas through the plurality of openings in the at least one screw conveyor to directly heat the contaminated solid media in each of the temperature zones to temperatures sufficient to volatilize one or more of the contaminants in the solid media;
means for withdrawing the volatilized contaminants and the hot, inert, non-condensible gas from the at least one screw conveyor and for holding a vacuum on the contaminated solid media;
means for controlling the rate of injecting the hot, inert, non-condensible gas so as to maintain the vacuum on the contaminated solid media;
means for separating the volatilized contaminants from the hot, inert, non-condensible gas;
and
means for discharging the solid media from the vacuum housing.

7 more elements

Dependencies are inferred from the claim text.