Union Oil Company of California

Kevin R Kitz

Darrell L Gallup

Donald M Fenton

Dennis L Saunders

William E Amend

Brian J Kelly

Manuel E Obando

Paul A Peaden

As geothermal steam containing contaminants such as boron, arsenic, and mercury is passed through a turbine-condenser system, the contaminants preferentially collect in the initial condensate produced from the steam. Collecting this initially-produced condensate and segregating it from the remainder of the steam being condensed ensures that condensate produced from the remainder of the steam is contaminants-lean, preferably containing the contaminants in concentrations allowing for discharge of the contaminants-lean condensate to the environment.

Geothermal steam processing

Sulfurous acid and/or sulfurous acid precursors, such as sulfur dioxide, are introduced into a hydrogen sulfide-containing geothermal brine or fluid prior to extracting energy from the resulting mixture by, e.g., passing the mixture through a flash vessel or a heat exchanger. The introduction of the sulfurous acid or its precursors into the geothermal brine or fluid inhibits scale formation and/or removes previously formed scale during processing of the brine or fluid.

pH modification of geothermal brine with sulfur-containing acid

Sulfur-containing acid is produced at a geothermal energy source from hydrogen sulfide produced as part of a geothermal process and introduced into aqueous liquid brine to lower the pH of the liquid brine. The lowered pH of the brine inhibits silica, metal sulfide and/or calcite formation on the surfaces of geothermal energy processing equipment or in subterranean formations in which the brine is injected.

An integrated system of non-condensable gas (NCG) and condensate treatment allows geothermal power plant condensate and non-condensable gas effluent streams containing H.sub.2 S and ammonia to be commercially useful for more than for cooling tower makeup. In the preferred embodiment, the pH of the condensate is increased by adding ammonia and the pH increased stream is contacted with NCG to scrub and oxidize the H.sub.2 S constituent of the NCG. By reducing the pH, the condensate or aqueous stream mixture can also be used to further transfer ammonia from the non-condensable gas stream to the aqueous stream, enriching the stream for use as a fertilizer/irrigation water mixture. If other commercial uses are desired for the mixture and/or oxidized NCG streams, they can be resin treated to remove the ammonia constituent. With the ammonia and H.sub.2 S constituents decreased, the condensate may be used for a variety of applications and the NCG can be injected or used as a commercial feed stream. Rejuvenation of the resin may be accomplished by recycling and purging with the treated NCG. The effluent purge gas may be used to further enrich irrigation waters. A nearly total elimination of all emissions from the geothermal power is thereby made possible.

Method to treat geothermal fluid streams

A method is provided for protecting flow-conducting elements, such as pipe, fittings, valves, and vessels which are constructed of austenitic and duplex stainless steel alloy materials and which are used in hot geothermal brine service from stress cracking caused by small amounts of the brine leaking onto exterior surfaces of such flow-conducting elements. According to the method, residual stress regions of the flow-conducting elements are thermally-sprayed with a metal such as mild steel, aluminum, magnesium, or zinc, which is anodic relative to the stainless steel, to provide a metal coating having a preferred thickness of between about 10 mils and about 20 mils, the preferred metal to be thermally-sprayed onto the stainless steel being mild steel. A metallized article made by the present method is provided.

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Metro Manila, Philippines

Kevin R Kitz