The Use of Electrochemical Techniques to Characterize Wet Steam Environments
The composition of a steam phase in equilibrium with a water phase at high temperature is remarkably affected by the varying capabilities of the water phase constituents to partition into the steam. Ionic impurities (sodium, chloride, sulfate, etc.) tend to remain in the water phase, while weakly ionic or gaseous species (oxygen) partition into the steam. Analysis of the water phase can provide misleading results concerning the steam phase composition or environment. This paper describes efforts that were made to use novel electrochemical probes and sampling techniques to directly characterize a wet steam phase environment in equilibrium with high temperature water. Probes were designed to make electrochemical measurements in the thin film of water existing on exposed surfaces in steam over a water phase. Some of these probes were referenced against a conventional high temperature electrode located in the water phase. Others used two different materials (typically tungsten and platinum) to make measurements without a true reference electrode. The novel probes were also deployed in a steam space removed from the water phase. It was necessary to construct a reservoir and an external, air-cooled condenser to automatically keep the reservoir full of condensed steam. Conventional reference and working electrodes were placed in the water phase of the reservoir and the novel probes protruded into the vapor space above it. Finally, water phase probes (both reference and working electrodes) were added to the hot condensed steam in the external condenser. Since the condensing action collapsed the volatiles back into the water phase, these electrodes proved to be extremely sensitive at detecting oxygen, which is one of the species of highest concern in high temperature power systems. Although the novel steam phase probes provided encouraging initial results, the tendency for tungsten to completely corrode away in the steam phase limited their usefulness. However, the conventional water phase electrodes, installed both in the reservoir and in the external condensing coil, provided useful data showing the adverse impact of oxygen and carbon dioxide on the REDOX potential and high temperature pH, respectively.
- Research Organization:
- Lockheed Martin Corporation, Schenectady, NY 12301 (US)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC12-00SN39357
- OSTI ID:
- 821376
- Report Number(s):
- LM-03K040; TRN: US200411%%40
- Resource Relation:
- Other Information: PBD: 30 Apr 2003
- Country of Publication:
- United States
- Language:
- English
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