Patent EA-001892-B1 (EA)
Title: System for processing oil refinery waste
Inventor: CONAWAY LAWRENCE M
IPC: B09C1/08
Filed: 1998-11-16
Abstract: 1. A method for treating an aqueous slurry of refinery wastes to provide effluent from which petroleum products may be recovered and a cake which is substantially free of hydrocarbon residues, comprising the steps of: a) heating said waste slurry to a temperature of at least about 180 degree F to form a hot sludge; b) maintaining said slurry at said temperature for a period of time sufficient to digest said hot sludge, said digestion including melting any entrained petroleum solids, reducing the apparent viscosity of the slurry, and reducing the density of petroleum fractions in said slurry; c) passing said hot digested slurry through a first centrifuge to separate a first liquid effluent containing liquid petroleum fractions from a first cake containing bound petroleum residues; d) dispersing said first cake in water to form a second slurry; e) treating said second slurry by adding an amount of hydrogen peroxide thereto to lyse and liberate said bound petroleum residues from inert solids contained in said first cake; and f) passing said second slurry through a second centrifuge to separate a second liquid effluent containing petroleum fractions from a second cake, said second cake containing said inert solids and being substantially free of hydrocarbon residues. 2. A method in accordance with Claim 1 further comprising the step of adjusting the weight of solids in said waste to about 5 percent or less prior to said heating step. 3. A method in accordance with Claim 1 further comprising the step of passing said aqueous slurry through a screen to remove large particles therefrom prior to said heating step. 4. A method in accordance with Claim 1 further comprising the step of directing said first and second liquid effluents to a refinery. 5. A method in accordance with Claim 1 further comprising the step of further dewatering said second cake after said second centrifugation step. 6. A method in accordance with Claim 1 wherein said treating step includes oxidizing polycyclic aromatic hydrocarbons in said second slurry. 7. A method in accordance with Claim 1 wherein said heating step includes injection of steam into said slurry. 8. A method in accordance with Claim 1 wherein at least one of said first and second centrifuges is a disc/bowl centrifuge. 9. A method in accordance with Claim 1 wherein said waste slurry comprises residuals resulting from activities selected from the group consisting of petroleum acquisition, petroleum transporting, petroleum storing, petroleum refining, and combinations thereof, said residuals being selected from the group consisting of sludges, bottoms, waxes, oils, greases, contaminated soils, and mixtures thereof. 10. A method in accordance with Claim 1 wherein said water in said dispersing step is heated. 11. A system for processing oil refinery waste to provide liquid effluent from which petroleum products may be recovered and a cake which is substantially free of hydrocarbon residues, comprising: a) a conditioning vessel for receiving, tempering, and otherwise thermally conditioning a slurry of said waste; b) a first centrifuge in communication with said conditioning vessel for receiving said conditioned slurry therefrom and separating said first slurry into a first liquid effluent and a first cake, said first effluent being refinable into petroleum products; c) a reactor vessel for receiving said first cake; d) means for dispensing hydrogen peroxide and water into said reactor vessel to form a second slurry with said first cake and to lyse and liberate bound petroleum resides from inert solids contained in said first cake; e) a second centrifuge in communication with said reactor vessel for receiving said second slurry therefrom and separating said second slurry into a second liquid effluent and a second cake, said second effluent being refinable into petroleum products and said second cake being substantially free of petroleum residues. 12. A system in accordance with Claim 11 wherein at least one of said first and second centrifuges is a disc/bowl centrifuge. 13. A system in accordance with Claim 11 wherein said conditioning vessel is provided with steam for said tempering of said slurry. 14. A system in accordance with Claim 11 further comprising at least one additional reactor vessel arranged for parallel flow with said first reactor vessel. 15. A system in accordance with Claim 11 further comprising means for maintaining non-explosive atmospheres within said conditioning and reactor vessels. 16. A system in accordance with Claim 11 further comprising a screen for filtering large particles from said waste before introducing said waste to said conditioning vessel. 17. A system in accordance with Claim 11 further comprising means for diluting said waste with water to a weight percentage of about 5 percent or less. 18. A system in accordance with Claim 17 further comprising means for capturing volatile hydrocarbons escaping from said slurries and combusting said hydrocarbons to heat said water. 19. A system in accordance with Claim 11 further comprising means for dewatering said second cake.