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U.S. Department of Energy
Office of Scientific and Technical Information

Method for regenerating scale solvent

Patent ·
OSTI ID:7233742
This patent describes improvement in the method for removing alkaline earth sulfate scale by contacting the scale with an aqueous solvent having a pH of about 8 to abut 14 and comprising a chelating agent comprising a polyaminopolycarboxylic acid or salt of such an acid, and a synergist anion. The improvement comprises removing alkaline earth sulfate scale dissolved in the aqueous solvent by: acidifying the aqueous solvent containing dissolved scale sufficiently to generate free alkaline earth metal ions without forming an insoluble alkaline earth precipitate; mixing the aqueous solvent with a liquid hydrocarbonaceous membrane phase containing a soluble surfactant and an oil soluble emulsifier, the liquid membrane emulsion enveloped around droplets of an internal aqueous phase comprising an aqueous solution having a pH of from about 8 to about 14 and a chelating agent comprising a polyaminopolycarboxylic acid or a salt of such an acid, wherein the free alkaline earth ions transfer from the solvent into the hydrocarbonaceous membrane and into the internal aqueous phase where the ions are removed by the chelating agent; and recovering the aqueous solvent and increasing the pH of the aqueous solvent to a value of about 10 to about 14 to produce a regenerated aqueous solvent for reuse.
Assignee:
Mobil Oil Corp., Fairfax, VA (United States)
Patent Number(s):
US 5087371; A
Application Number:
PPN: US 7-612728
OSTI ID:
7233742
Country of Publication:
United States
Language:
English