Patent EA-004332-B1 (EA)
Title: A method for recovering water soluble surfactants
Inventor: BLYTAS GEORGE CONSTANTINE
IPC: C09K8/52
Filed: 2000-11-21
Abstract: 1. A method for separating and recovering a surfactant selected from the group consisting of water soluble ionic surfactants and hydrocarbon partitioning, but waterhydrocarbon interface preferring, ionic surfactants from a substance containing water as an aqueous polar solvent selected from the group consisting of aqueous solutions, water/hydrocarbon dispersions, and water/hydrocarbon emulsions, which comprises: a) adding a second polar solvent that is nonaqueous and a salt which modifies the ionic strength of said aqueous and added polar solvents resulting in two separate polar solvent phases, wherein said ionic surfactant principally partitions into the added polar phase and said salt partitions principally into the aqueous phase; b) separating the phases and recovering the surfactant using a customary equipment. 2. The method of Claim 1 wherein said surfactants are selected from single and polymeric surfactants. 3. The method of Claim 1wherein the added nonaqueous polar solvent is selected from water miscible, partially miscible in water, and water immiscible polar solvents. 4. The method of Claim 2 wherein the single or polymeric ionic surfactant is cationic. 5. The method of Claim 3 wherein the nonaqueous polar solvent is a light alcohol having less than 6 carbons. 6. The method of Claim 5 wherein the alcohols are selected from a group including methanol, ethanol, isopropanol, branched isobutanols, secondary butanol, and tertiary-butanol. 7. The method of Claim 1 wherein the nonaqueous solvent is a light diol or glycol with less than 6 carbons. 8. The method of Claim 1 wherein the nonaqueous solvent is a glycol selected from the group consisting of monoethylene glycol, diethylene glycol, triethylene glycol. 9. The method of Claim 1wherein the second polar solvent is selected from acetone, methylethylketone, acetate esters, and formate esters. 10. The method of Claim 4 wherein the cationic surfactants are selected from salts of long chain fatty acids and quaternary ammonium, phosphonium, or ternary sulphonium salts. 11. The method of Claim 10 wherein the cationic surfactants can be represented by the structure: wherein X is chosen from S, N-R4, P-R4 and S, N, and P are sulfur, nitrogen, phosphorous, respectively; wherein plus represents cations and minus denotes anions; wherein Y is selected from bromide, chloride, iodide, fluoride; wherein no more than two of R1 to R4 are independently selected from the group consisting of normal or branched chain alkyls having more than 3 and up to 6 carbon atoms which may include one or more ether links or ester branches, and wherein one or more carbons may be substituted by another atom; wherein at least one of R1 to R4 but no more than two, is an organic moiety containing 8 to 20 carbon atoms, which may include one or more ether links or ester branches and wherein one or more carbon atoms may be substituted by heteroatoms and where the chain can be broadly chosen from alkyls, alkenyls, aryls, arylalkyls, arylalkenyls, alkylaryls, and alkenylaryls; and wherein no more than two of R1 to R4, are hydrogen or other organic moiety containing heteroatoms and ether links and ester branches. 12. The method of Claim 11 wherein in the case of quaternary alkylated compounds having three alkyl groups, the fourth group can vary broadly, without significant alteration of hydrate inhibiting properties. 13. The method of Claim 12 further comprising the fourth group being bonded to any suitable polymeric backbone. 14. The method of Claim 13 wherein the polymeric backbone is selected from polyacrylic acid, polymers and copolymers of N-vinyl-2-pyrrolidone. 15. The method of Claim 4 wherein the cationic surfactant further comprises a hydrate growth inhibitor/modifier compound and the substance selected from aqueous solutions, water/hydrocarbon dispersions and water/hydrocarbon emulsions comprises produced fluids from hydrocarbon production wells. 16. The method of claim 15 wherein the produced fluids comprise an aqueous flowing mixture comprising an amount of hydrocarbons, other gases, and an amount of water wherein the amount and type of hydrocarbons, other gases, and water are sufficient to form hydrates at conduit temperatures and pressures. 17. The method of Claim 15 wherein the amount of ionic surfactant hydrate inhibitor in the process fluids is from about 0.05 to 5.00 percent by weight based on production water present. 18. The method of Claim 17 wherein the amount of ionic surfactant hydrate inhibitor in the process fluids is from about 0.1 to 1.0 percent by weight based on production water. 19. The method of Claim 15 further comprising the hydrate compound inhibitor having been dissolved in at least one polar solvent to facilitate injection into the produced stream. 20. The method of Claim 19 further comprising at least one polar solvent comprising an antifreeze in terms of reducing the temperature at which hydrates begin to form. 21. The method of Claim 19 wherein the polar solvent functions as both a solvent for a hydrate compound inhibitor and an antifreeze. 22. The method of Claim 19 further comprising at least one polar solvent capable of extracting hydrocarbon partitioning ionic surfactants, singly or bound to polymeric backbones, from the water/hydrocarbon mixture. 23. The method of Claim 18 wherein the amount of polar solvents in the process fluids is in the range of 0 to 30 percent by weight based on produced water. 24. The method of Claim 1 wherein the salt is inorganic salt and is selected from salts of elements of Group IA, IIA, IIB, or VIII of the Periodic Table. 25. The method of Claim 24 wherein the salt is selected from chlorides, bromides, or iodides of sodium, calcium, magnesium, potassium, zinc, and iron. 26. The method of Claim 25 wherein the salts are selected from nitrates, nitrites, and thiocyanates. 27. The method of Claim 16 further comprising the hydrate inhibiting/modifying ionic surfactant is recovered at normal hydrocarbon production separation facilities. 28. The method of Claim 27 further comprising the hydrate inhibiting/modifying ionic surfactant is recovered at the low pressure end of normal hydrocarbon production separation facilities at the end of flow lines in one or more steps. 29. The method of Claim 28 further comprising the recovered hydrate inhibiting/modifying compound is recycled after separation. 30. The method of Claim 29 further comprising appropriate addition of makeup compounds, surfactants/polar solvents/ salts prior to recycling to wellheads.