Ionic contact media for electrodes and soil in conduction heating

• US 5,586,213 A
• Filed: 02/05/1992
• Issued: 12/17/1996
• Est. Priority Date: 02/05/1992
• Status: Expired due to Fees

• Current Assignee: Alion Science and Technology Corporation
• Original Assignee: IIT Research Institute (Alion Science & Technology Corp.)
• Inventors: Jambor, Richard, Bridges, Jack E., Sresty, Guggilam C., Dev, Harsh
• Primary Examiner(s): Jeffery, John A.
• Application Number:
  US07/831,768
• Time in Patent Office: 1,777 Days
• Field of Search: 392/311, 392/301, 392/305, 392/306, 392/312, 166/248, 166/302, 166/60, 175/16, 405/131
• US Class Current: 392/312
• CPC Class Codes: B09C 1/062 by using electrode or resistance heating elements
• CPC Class Codes: B09C 2101/00 In situ
• CPC Class Codes: E02D 3/11 by thermal, electrical or electro-chemical means freezing soil for interrupting passage of underground water E02D19/14
• CPC Class Codes: E21B 36/005 Heater surrounding production tube
• CPC Class Codes: E21B 36/04 using electrical heaters
• CPC Class Codes: E21B 43/2401 by means of electricity
• CPC Class Codes: H05B 3/60 Heating arrangements wherein the heating current flows through granular powdered or fluid material, e.g. for salt-bath furnace, electrolytic heating H05B3/38 takes precedence

Abstract

Ionic contact is established and maintained between electrodes and soil in ohmic heating of a subsurface formation for recovery of volatile and semi-volatile materials, such as hazardous waste, hydrocarbon-like materials, and valuable minerals having thermally responsive properties. A compressed, dry sponge is wrapped around an electrode, which is then inserted into a bore hole. A conductive liquid is added to the bore hole, causing the sponge to swell, creating a stable and substantial interface for the flow of heating currents.

Claims

1. A method of increasing ionic contact between an electrode and a subsurface formation in electric heating of said subsurface formation for the recovery of volatiles and semi-volatiles, comprising the steps of:

forming a hole in a subsurface formation;

contacting an electrode with a dry, compressed sponge;

inserting said electrode and said compressed sponge into said hole, said compressed sponge and said hole defining an at least partially open bore hole region between said compressed sponge and said hole;

adding an electrically conductive liquid to said hole, to cause said compressed sponge to substantially fill an annular region between the electrode and said subsurface formation defining the bore hole, thereby providing a conductive ionic contact between the electrode and subsurface formation; and

providing an ohmic heating current to said electrodes to heat said subsurface formations to evolve volatiles and semi-volatiles as gas or vapor for recovery.

2. A method of increasing ionic contact between an electrode and soil in electric heating of subsurface formations for the recovery of volatiles and semi-volatiles according to claim 1, wherein said dry compressed sponge is comprised of cellulose material.

3. A method of increasing ionic contact between an electrode and soil in electric heating of subsurface formations for the recovery of volatiles and semi-volatiles according to claim 1, wherein said compressed sponge comprises a plurality of electrically conductive fibers.