| abstract |
A process is provided for controlling the emission of hydrogen sulfide from, and the growth of living organisms in, steam condensate cooling towers and catch basins used in conjunction with steam and condensate of steam derived from hydrogen sulfide-containing geothermal brine. The process comprises contacting the condensate, in a substantially continuous manner, with a small, substantially less-than-stoichiometric amount of an oxidizing biocide, such as trichloro-isocyanuric acid or oxidizing biocide, such as trichloro-isocyanuric acid or 1-bromo-3-chloro-5,5-dimethyl-hydantoin, which results in the oxidation of such hydrogen sulfide precursors as ammonium bisulfide in the condensate to a water-soluble sulfite and/or sulfate, and which slows the growth of organisms in the cooling tower and catch basin. The process additionally includes periodically contacting the condensate with larger amounts of a second biocide, such as dodecylguanidine hydrochloride or isothiazalone, which provides most of the control of organism growth in the cooling tower and catch basin. Still further, the process includes combining hydrogen sulfide gas separated from the steam with the condensate for treatment therewith. To prevent system corrosion, the process may include treating the condensate with a non-organic, phosphate-based corrosion inhibitor and scale dispersant. |