Polar solvent extraction and dedusting process

A process for producing and dedusting oil from synthetic fuels, comprising the steps of:

• feeding solid hydrocarbon-containing material selected from the group consisting essentially of oil shale and tar sands, into an aboveground retort;
• feeding solid heat carrier material comprising combusted solid hydrocarbon-containing material into said aboveground retort;
• retorting said solid hydrocarbon-containing material by mixing said solid hydrocarbon-containing material with said solid heat carrier material into said aboveground retort at a sufficient retorting temperature to liberate an effluent product stream of hydrocarbons and entrained particulates of dust selected from the group consisting of raw, retorted, and combusted solid hydrocarbon-containing material and combinations thereof;
• separating a fraction of normally liquid oil containing a substantial portion of said entrained particulates from said effluent product stream;
• dissolving said fraction in dedusting solvents having molecular weights less than 130 grams per mole, said dedusting solvents including both a polar solvent and a non-polar solvent;
• said polar solvent comprising alcohols containing 1 to 4 carbon atoms;
• said non-polar solvent comprising alkanes containing 3 to 9 carbon atoms;
• separating said dissolved fraction into a dedusted stream of solvents and oil containing a substantially lower concentration of particulates than said fraction and a particulate-laden residual stream of solvents and oil having a substantially higher concentration of said particulates than said fraction;
• and
• combusting said particulate-laden residual stream and said retorted material for use as said solid heat carrier material in said aboveground retort.

A process for dedusting shale oil, comprising the steps of:

• dissolving heavy shale oil containing from 1% to 65% by weight oil shale particulates ranging in size from less than 1 micron to 1000 microns in dedusting solvents having a molecular weight less than 100 grams per mole, said dedusting solvents comprising both a polar solvent and a non-polar solvent;
• said polar solvent comprising methanol;
• said non-polar solvent comprising alkanes containing 4 to 8 carbon atoms;
• separating said dissolved heavy shale oil into a substantially dedusted stream and a dust-enriched stream;
• said dedusted stream comprising 15% to 30% by weight heavy shale oil, 70% to 85% by weight polar and non-polar solvents, and a maximum of 1% by weight oil shale particulates;
• and
• said dust-enriched stream comprising 30% to 75% by weight oil shale particulates, 12% to 68.5% by weight Polar and non-polar solvents, and 1.5% to 13% by weight heavy shale oil.

A process for producing and dedusting shale oil, comprising the steps of:

• feeding raw oil shale into a surface retort selected from the group consisting essentially of a screw conveyor retort with a surge bin, a rotating pyrolysis drum with an accumulator having a rotating trommel screen, a fluid bed retort, a static mixer retort with a surge bin, and a gravity flow retort;
• feeding solid heat carrier material at a temperature ranging from 1000.degree. F. to 1400.degree. F. into said retort, said solid heat carrier material comprising both spent oil shale and combusted sludge;
• retorting said raw oil shale by contacting said raw oil shale with said solid heat carrier material at a sufficient temperature to liberate an effluent product stream of hydrocarbons and entrained particulates of raw, retorted and combusted oil shale dust ranging in size from less than one micron to 1000 microns;
• partially dedusting said effluent product stream in at least one gas-solids separation device selected from the group consisting essentially of a cyclone and a filter;
• separating a fraction of normally liquid shale oil containing from 1% to 65% by weight of said shale dust in at least one separator selected from the group consisting essentially of a fractionator, scrubber, and quench tower;
• feeding said fraction at a temperature above the pour point of said shale oil to at least one solvent deduster selected from the group consisting essentially of a mixer settler, extraction column, tower, leacher, and vessel;
• feeding a polar solvent comprising methanol into said deduster;
• feeding a non-polar solvent into said deduster, said non-polar solvent having at least one constituent selected from the group consisting essentially of alkanes containing 4 to 8 carbon atoms and light shale oil;
• feeding recycled solvents comprising recycled polar solvent and recycled non-polar solvent into said deduster;
• the solvent feed ratio of non-polar solvent to polar solvent being fed into said deduster ranging from 1:10 to 3:1;
• the oil feed ratio of shale oil to polar and non-polar solvents being fed into said deduster ranging from 1:7 to 2:1;
• separating said fraction in said deduster into a substantially dedusted product stream and a dust-enriched stream by mixing and dissolving said fraction in said solvents and settling said dust-enriched stream in said deduster at a rate ranging from 10 feet per hour to 1200 feet per hour, said mixing being selected from the group consisting essentially of mechanical mixing, mixing with the aid of stationary internals, pressure driven static mixing, and combinations thereof, said fraction being separated at a temperature from 100.degree. F. to 500.degree. F. at a pressure from 1 atmosphere to 500 psia at a solids residence time of 10 minutes to 120 minutes and at a liquid residence time of 5 minutes to 60 minutes;
• said dedusted product stream containing 15% to 30% by weight shale oil, 70% to 85% by weight polar and non-polar solvents, and a maximum of 1% by weight oil shale dust;
• said dust-enriched stream containing 30% to 75% by weight oil shale dust, 12% to 68.5% by weight polar and non-polar solvents, and 1.5% to 13% by weight shale oil;
• heating said dust-enriched stream in a dryer selected from the group consisting essentially of a porcupine dryer, a screw conveyor dryer, a fluid bed dryer, a disc dryer, and an evaporator, to a drying temperature ranging from 150.degree. F. to 950.degree. F. to separate said dust-enriched stream into a substantially dedusted solvent stream of polar and non-polar solvents and a dried residal stream of dust-laden sludge containing oil shale dust and shale oil;
• recycling said dedusted solvent stream from said dryer to said deduster for use as part of said recycled solvents;
• combusting said dried residual stream and said retorted shale in a combustor selected from the group consisting of a lift pipe combustor, a generally horizontal combustor and a fluid bed combustor, to form combusted sludge and spent shale, respectively;
• recycling and using said combusted sludge and said spent shale as said solid heat carrier material in said surface retort;
• recovering and separating most of said solvents from said dedusted product stream to form a recovered solvent stream of polar and non-polar solvents and a substantially solvent-free oil stream containing from about 90% to about 99.95% by weight shale oil, about 0.05% to about 10% by weight polar and non-polar solvent, and a maximum of about 1% by weight oil shale dust;
• and
• recycling said recovered solvent stream to said deduster for use as part of said recycled solvents.