Measurement of pH and potential in supercritical water

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

OSTI ID:6835881

Hettiarachchi, S; Song, H; Emerson, R; Macdonald, D D

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: SRI International, Menlo Park, CA (United States)
• Sponsoring Organization: EPRI; Electric Power Research Inst., Palo Alto, CA (United States)
• OSTI ID: 6835881
• Report Number(s): EPRI-TR-102277-Vol.1
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
47 OTHER INSTRUMENTATION
36 MATERIALS SCIENCE
ALLOYS
CORROSION
ELECTRIC POTENTIAL
MONITORING
ELECTRODES
PERFORMANCE TESTING
FOSSIL-FUEL POWER PLANTS
COOLING SYSTEMS
PH VALUE
WATER
CORROSIVE EFFECTS
SUPERCRITICAL STATE
CHEMICAL PROPERTIES
CHLORIDES
ELECTROCHEMICAL CELLS
ELECTROCHEMISTRY
EPRI
GLASS
METALS
SPECIFICATIONS
WATER CHEMISTRY
ZIRCONATES
CHEMICAL REACTIONS
CHEMISTRY
CHLORINE COMPOUNDS
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
OXYGEN COMPOUNDS
POWER PLANTS
TESTING
THERMAL POWER PLANTS
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
200101* - Fossil-Fueled Power Plants- Cooling & Heat Transfer Equipment & Systems
440800 - Miscellaneous Instrumentation- (1990-)
360105 - Metals & Alloys- Corrosion & Erosion