Measurement of pH and potential in supercritical water. Volume 1: Development of sensors: Final report

Technical Report · Thu Apr 01 04:00:00 EST 1993

OSTI ID:10149436

Hettiarachchi, S; Song, H; Emerson, R; Macdonald, D D ^[1]

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1. SRI International, Menlo Park, CA (United States)

Two of the most important parameters in defining the chemical properties of supercritical water used in fossil power plants and the corrosion properties of metals immersed in these environments are the electrochemical potential and pH, both measured at the temperature of operation. The broad overall goal of this program was to develop reference electrodes and pH sensors that would operate at temperatures and pressures corresponding to supercritical water. The program was intended to establish the proof of concept, and demonstrate the viability of fabricating and using sensors for operation under these extreme conditions. During this study SRI fabricated an yttria-stabilized zirconia (YSZ) pH sensor with a Hg/HgO internal reference and proved the thermodynamic viability of using this as a pH sensor at temperatures above the critical point of water (i.e., {ge}374{degree}C). A novel all-solid-state Ag/AgCl, (Cl{sup {minus}}, glass) reference electrode was also fabricated in which the solid electrolyte is a chloride-ion-doped glass having a constant chloride ion activity. The electrode was tested as a valid reference electrode at 374{degree}C. It is rugged and leakproof and is expected to be stable over long periods of time because of the extremely slow diffusion of Cl{sup {minus}} ions through the solid glass matrix.

• Research Organization: Electric Power Research Inst., Palo Alto, CA (United States); SRI International, Menlo Park, CA (United States)
• Sponsoring Organization: Electric Power Research Inst., Palo Alto, CA (United States)
• OSTI ID: 10149436
• Report Number(s): EPRI-TR--102277-Vol.1; ON: UN93013031
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
200101
36 MATERIALS SCIENCE
360105
440800
47 OTHER INSTRUMENTATION
ALLOYS
CHEMICAL PROPERTIES
CHLORIDES
COOLING AND HEAT TRANSFER EQUIPMENT AND SYSTEMS
COOLING SYSTEMS
CORROSION
CORROSION AND EROSION
CORROSIVE EFFECTS
ELECTRIC POTENTIAL
ELECTROCHEMICAL CELLS
ELECTROCHEMISTRY
ELECTRODES
EPRI
FOSSIL-FUEL POWER PLANTS
GLASS
METALS
MISCELLANEOUS INSTRUMENTATION
MONITORING
PERFORMANCE TESTING
PH VALUE
SPECIFICATIONS
SUPERCRITICAL STATE
WATER
WATER CHEMISTRY
ZIRCONATES