US 5,053,082 AGranted

Process and apparatus for cleaning particulate solids

AssigneeConoco Inc.

InventorsDavid A. Flanigan, Joe K. Heilhecker, Robert E. Williams

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Abstract

A system for cleaning solids contaminated with solvent-soluble contaminants. The system, which includes both process and apparatus, comprises slurrying of the solids with a solvent, feeding the slurry to a cyclone separation zone integrally connected to a countercurrent extraction zone, separating the slurry into an overflow stream which includes solvent and fine particles of solids and an underflow stream which includes mostly coarse particles of solids in the cyclone separation zone, processing the overflow stream in a cleaning zone with additional solvent, processing the underflow stream in countercurrent relationship with additional solvent through the countercurrent extraction zone, combining the cleaned coarse particles of solids withdrawn from the extraction zone with the cleaned fine particles of solids withdrawn from the cleaning zone and centrifuging the combined cleaned particles to remove residual solvent and recovering the combined solids having reduced contamination for disposal.

Claims38

Dependent claims

A process for cleaning solids contaminated with a solvent-soluble contaminant which comprises:

(a) mixing contaminated solids comprising a mixture of fine and coarse particles with a solvent for the solvent-soluble contaminant to form a slurry,
(b) introducing the resulting slurry to a cyclone separation zone,
(c) withdrawing a first stream from an overflow of the cyclone separation zone, said first stream comprising a mixture of fine particles and a major amount of solvent containing a relatively high concentration of dissolved contaminant,
(d) separating the fine particles having reduced contamination from the first stream and contacting said separated fine particles with additional solvent in a cleaning zone, said additional solvent containing no more than a relatively low concentration of dissolved contaminant, and withdrawing a mixture of said fine particles and at least some of said additional solvent from the cleaning zone,
(e) withdrawing a second stream from an underflow of the cyclone separation zone, said second stream comprising a mixture of coarse particles and a minor amount of solvent containing a relatively high concentration of dissolved contaminant, and introducing said second stream directly into a body of solvent contained in an upper portion of an extraction zone, said underflow being contiguous with or immersed in said body of solvent to the extent that back pressure is provided to the cyclone separation zone without flooding of said cyclone separation zone,
(f) introducing a solvent containing no more than a relatively low concentration of dissolved contaminant into the extraction zone adjacent the lower portion thereof and counter-currently contacting said second stream with said solvent in said extraction zone,
(g) withdrawing a solvent stream containing a relatively high concentration of dissolved contaminant adjacent the upper portion of the extraction zone and withdrawing coarse particles having reduced contamination together with some solvent containing no more than a relatively low concentration of dissolved contaminant from the lower portion of the extraction zone,
(h) combining the withdrawn coarse particles and solvent from step (g) with the withdrawn fine particles and solvent from step (d) and centrifuging the combination to remove the solvent from the coarse and fine particles and recovering the centrifuged coarse and fine particles having reduced contamination for disposal.

5 more elements

A process for cleaning drill cutting solids contaminated with oil which comprises:

(a) mixing the oil-contaminated drill cutting solids comprising both fine and coarse particles with a solvent for the oil to form a slurry,
(b) introducing the resulting slurry to a cyclone separation zone,
(c) withdrawing a first stream from an overflow of the cyclone separation zone, said first stream comprising a mixture of fine particles of drill cutting solids and a major amount of solvent containing a relatively high concentration of dissolved oil,
(d) separating the fine particles of drill cutting solids having reduced oil contamination from the first stream and contacting said separated fine particles with additional solvent in a cleaning zone, said additional solvent containing no more than a relatively low concentration of dissolved oil, and withdrawing a mixture of said fine particles and at least some of said additional solvent from the cleaning zone,
(e) withdrawing a second stream from an underflow of the cyclone separation zone, said second stream comprising a mixture of coarse particles of drill cutting solids and a minor amount of solvent containing a relatively high concentration of dissolved oil, and introducing said second stream directly into a body of solvent contained in an upper portion of an extraction zone, said underflow being contiguous with or immersed in said body of solvent to the extent that back pressure is provided to the cyclone separation zone without flooding of said cyclone separation zone,
(f) introducing a solvent containing no more than a relatively low concentration of dissolved oil into the extraction zone adjacent the lower portion thereof and counter-currently contacting said second stream with said solvent in said extraction zone,
(g) withdrawing a solvent stream containing a relatively high concentration of dissolved oil adjacent the upper portion of the extraction zone and withdrawing coarse particles of drill cutting solids having reduced oil contamination together with some solvent containing no more than a relatively low concentration of dissolved oil from the lower portion of the extraction zone,
(h) combining the withdrawn coarse particles of drill cutting solids and solvent from step (g) with the withdrawn fine particles of drill cutting solids and solvent from step (d) and centrifuging the combination to remove the solvent from the coarse and fine particles,
(i) introducing the centrifuged coarse particles and fine particles of drill cutting solids from step (h) to a heating zone and conveying said coarse and fine particles through said zone at temperatures sufficient to volatilize substantially all residual solvent from said particles and recovering substantially solvent-free particles of drill cutting solids having reduced contamination for disposal.

6 more elements

An apparatus for cleaning solids contaminated with a solvent-soluble contaminant which comprises:

(a) slurry means for mixing contaminated solids, comprising a mixture of fine and coarse particles, with a solvent for the solvent-soluble contaminant,
(b) cyclone separation means connected to the slurry means for receiving and separating said slurry into a first stream comprising a mixture of fine particles and a major amount of solvent containing a relatively high concentration of dissolved contaminant and a second stream comprising a mixture of coarse particles and a minor amount of solvent containing a relatively high concentration of dissolved contaminant, said cyclone separation means including an overflow for withdrawing said first stream and an underflow for withdrawing said second stream,
(c) an extraction column whose upper portion is integrally connected with the underflow of the cyclone separation means and adapted to receive said second stream while providing back pressure to said cyclone separation means, said extraction column having solvent inlet means near its lower portion for receiving solvent having no more than a relatively low concentration of dissolved contaminant, solvent outlet means near its upper portion for withdrawing solvent having a relatively high concentration of dissolved contaminant and a solids outlet near its lower portion below the solvent inlet means for discharge of coarse particles and some solvent,
(d) separation means connected to the overflow of the cyclone separation means for receiving and separating said first stream into a solvent stream containing a relatively high concentration of dissolved contaminant and a fine particle stream,
(e) cleaning means connected to separation means (d) for receiving and contacting said fine particle stream with additional solvent and having a solids outlet for discharge of fine particles and at least some solvent,
(f) centrifuge means connected to the solids outlet of said cleaning means and the solids outlet of said extraction column for receiving and separating the combined fine and coarse particles from the solvent.

3 more elements

An apparatus for cleaning drill cutting solids contaminated with oil which comprises:

(a) slurry means for mixing oil-contaminated drill cutting solids, comprising a mixture of fine and coarse particles, with a solvent for the oil,
(b) cyclone separation means connected to the slurry means for receiving and separating said slurry into a first stream comprising a mixture of fine particles of drill cutting solids and a major amount of solvent containing a relatively high concentration of dissolved oil and a second stream comprising a mixture of coarse particles of drill cutting solids and a minor amount of solvent containing a relatively high concentration of dissolved oil, said cyclone separation means including an overflow for withdrawing said first stream and an underflow for withdrawing said second stream,
(c) an extraction column whose upper portion is integrally connected with the underflow of the cyclone separation means and adapted to receive said second stream while providing back pressure to said cyclone separation means, said extraction column having solvent inlet means near its lower portion for receiving solvent having no more than a relatively low concentration of dissolved oil, solvent outlet means near its upper portion for withdrawing solvent having a relatively high concentration of dissolved oil and a solids outlet near its lower portion below the solvent inlet means for discharge of coarse particles of drill cutting solids and some solvent,
(d) first centrifuge means connected to the overflow of the cyclone separation means for receiving and separating said first stream into a solvent stream containing a relatively high concentration of dissolved oil and a fine particle stream,
(e) cleaning means connected to the first centrifuge means for receiving and contacting said fine particle stream with additional solvent and having a solids outlet for discharge of fine particles of drill cutting solids and some solvent,
(f) second centrifuge means connected to the solids outlet of said cleaning means and the solids outlet of said extraction column for receiving and separating the combined fine and coarse particles of drill cutting solids from the solvent,
(g) heating means connected to the second centrifuge means and adapted to receive the combined fine and coarse particles of drill cutting solids and volatilize the residual solvent to recover substantially solvent-free particles of drill cutting solids having reduced contamination for disposal.

4 more elements

Dependencies are inferred from the claim text.