Process for cleaning particulate solids
AssigneeConoco Inc.
InventorsDavid A. Flanigan, Robert E. Williams
Life of this patent
Estimating the term…
Abstract
A system for cleaning solids contaminated with solvent-soluble contaminants. The system, which includes both process and apparatus, comprises the use of at least two successive cleaning zones, each of which includes a slurrying stage and a centrifuge separation stage, wherein the solids to be cleaned and the solvent used for cleaning flow in countercurrent relationship to each other between the successive zones.
Claims18
A process for cleaning solids contaminated with solvent-soluble contaminant which comprises:
- (a) in an initial cleaning zone (i) feeding said contaminated solids and a solvent to a slurrying stage where the solvent contacts the solids thereby dissolving solvent-soluble contaminant and forms a slurry, (ii) withdrawing the slurry from the slurrying stage and introducing the slurry to a centrifuging stage where the slurry is centrifuged to separate the solids having reduced contamination from the solvent containing dissolved contaminant, and (iii) discharging the solids having reduced contamination from the centrifuging stage of the initial cleaning zone to a successive cleaning zone in series with the initial cleaning zone;
- (b) in at least one successive cleaning zone (i) feeding the solids having reduced contamination discharged from the centrifuging stage of the initial or immediately preceding cleaning zone and a solvent to a slurrying stage where the solvent contacts the solids thereby dissolving further solvent-soluble contaminant and forms a slurry, (ii) withdrawing the slurry from the slurrying stage and introducing the slurry to a centrifuging stage where the slurry is centrifuged to separate the solids having further reduced contamination from the solvent containing dissolved contaminant, and (iii) discharging the solids having reduced contamination from the centrifuging stage to the next successive cleaning zone or to disposal if there is no further successive cleaning zone,
- said process being further characterized in that (1) the initial cleaning zone and each successive cleaning zones are arranged in series with respect to one another and (2) fresh solvent is fed to the slurrying stage of the last successive cleaning zone and the solvent separated from the solids in the centrifuging stage of the last and any preceding cleaning zone is fed as the solvent to the slurrying stage of the next preceding cleaning zone whereby the flow of solids from cleaning zone to cleaning zone is in countercurrent relationship to the flow of solvent from cleaning zone to cleaning zone while a concurrent flow relationship exist within each individual cleaning zone.
A process for cleaning drill cutting solids contaminated with oil which comprises:
- (a) in an initial cleaning zone (i) feeding said oil-contaminated drill cutting solids and a solvent to a slurrying stage where the solvent contacts the solids thereby dissolving the oil contaminant and forms a slurry, (ii) withdrawing the slurry from the slurrying stage and introducing the slurry to a centrifuging stage where the slurry is centrifuged to separate the solids having reduced oil-contamination from the solvent containing dissolved oil contaminant, and (iii) discharging the solids having reduced oil-contamination from the centrifuging stage of the initial cleaning zone to a successive cleaning zone in series with the initial cleaning zone;
- (b) in at least one successive cleaning zone (i) feeding the solids having reduced contamination discharged from the centrifuging stage of the initial or immediately preceding cleaning zone and a solvent to a slurrying stage where the solvent contacts the solids thereby dissolving further oil contaminant and forms a slurry, (ii) withdrawing the slurry from the slurrying stage and introducing the slurry to a centrifuging stage where the slurry is centrifuged to separate the solids having further reduced oil-contamination from the solvent containing dissolved oil contaminant, and (iii) discharging the solids having reduced oil-contamination from the centrifuging stage to the next successive cleaning zone or to disposal if there is no further successive cleaning zone,
- said process being further characterized in that (1) the initial cleaning zone and each successive cleaning zones are arranged in series with respect to one another, and (2) fresh solvent is fed to the slurrying stage of the last successive cleaning zone and the solvent separated from the solids in the centrifuging stage of the last and any preceding cleaning zone is fed as the solvent to the slurrying stage of the next preceding cleaning zone whereby the flow of solids from cleaning zone to cleaning zone is in countercurrent relationship to the flow of solvent from cleaning zone to cleaning zone while a concurrent flow relationship exist within each individual cleaning zone.
In a process wherein a slurry of solids containing residual solvent-soluble contaminant and solvent containing dissolved contaminant is separated into a solids stream containing residual solvent-soluble contaminant and residual solvent and a solvent stream containing dissolved contaminant and said solids stream is introduced to a heating zone and conveyed through said heating zone at temperatures sufficient to volatilize substantially all of the solvent while stripping some of the residual solvent-soluble contaminant, the improvement therein comprising introducing additional solvent to said solids stream prior to the heating zone whereby stripping of residual solvent-soluble contaminant is enhanced.
Dependencies are inferred from the claim text.