Method to neutralize hydrogen chloride in superheated geothermal steam without destroying superheat

Abstract

Hydrogen chloride in superheated steam is neutralized by contacting the steam with a solution containing potassium carbonate. A solution of potassium carbonate will remain liquid when contacted by steam superheated by as much as 40° C. and, unlike sodium carbonate, the degree of superheat of a saturated solution of potassium carbonate increases with temperature. Other highly soluble potassium salts or salt inhibitors can be added to prevent precipitation of solid potassium chloride which may occur under certain conditions, or a small amount of additional water can be added to keep the potassium chloride in solution while allowing the steam to remain superheated. Injection of potassium carbonate solution downhole in a dry steam geothermal well to protect the well casing from corrosion is especially beneficial, because only a small amount of carrier water needs to be injected together with the potassium carbonate, whereby the steam remains superheated and the possibility of localized corrosion is avoided.