Development of a solid-electrolyte oxygen sensor for in situ oil shale retorting applications: final report

Technical Report · Wed Mar 01 04:00:00 EST 1978

OSTI ID:7175103

Haaland, D M

A new solid-electrolyte oxygen sensor has been developed suitable for air-fired in situ oil shale retorting applications. By eliminating the flowing gas reference of conventional solid-electrolyte sensors, only electrical leads to the surface are required for oxygen monitoring. The new design consists of two electrochemical cells of stabilized-zirconia solid electrolyte sealed into a small unit. One electrochemical cell monitors the ratio of oxygen partial pressures inside and outside the sensor while the second cell is used as a quantitative electrochemical oxygen pump. The initial measurement procedure requires that all oxygen be electrochemically removed from the known internal volume of the sensor by applying a potential across the second cell. The polarity of the potential is then reversed so that oxygen from the surrounding gas is electrochemically pumped back into the sensor. When the emf of the first cell reaches zero, the oxygen partial pressure inside the sensor is equal to that of the surrounding gas. Integrating the current required to achieve this condition yields the number of moles of oxygen pumped into the sensor. This information is used in the ideal gas law to calculate oxygen partial pressures. Tests of these sensors were conducted from 400 to 1000/sup 0/C in clean mixtures of oxygen and nitrogen spanning about 0.1 to 21% oxygen concentration range with reasonable accuracy. Tests in non-equilibrium gas mixtures of combustible gases in the presence of oxygen indicated significant catalytic reaction at the surface of the platinum electrodes. Thus accurate bulk gas phase oxygen measurements could not be made with sensors using pure platinum electrodes. Extensive studies of a variety of less catalytic electrode materials were made. The best results were obtained using a 50/50 mixture of PbS/Pt over sputtered platinum. These electrodes were non-catalytic above approximately 550/sup 0/C.

• Research Organization: Sandia Labs., Albuquerque, N.Mex. (USA)
• DOE Contract Number: EY-76-C-04-0789
• OSTI ID: 7175103
• Report Number(s): SAND-78-0319
• Country of Publication: United States
• Language: English

Related Subjects

04 OIL SHALES AND TAR SANDS
040401* -- Oil Shales & Tar Sands-- In Situ Methods
True & Modified
440300 -- Miscellaneous Instruments-- (-1989)
47 OTHER INSTRUMENTATION
BITUMINOUS MATERIALS
CARBONACEOUS MATERIALS
CHALCOGENIDES
DESIGN
ELECTRODES
ELECTROLYTES
ELEMENTS
ENERGY SOURCES
FOSSIL FUELS
FUELS
IN-SITU PROCESSING
IN-SITU RETORTING
LEAD COMPOUNDS
LEAD SULFIDES
MATERIALS
MEASURING INSTRUMENTS
METALS
OIL SHALES
OXYGEN METERS
PLATINUM
PLATINUM METALS
PROCESSING
REMOTE SENSING
RETORTING
SULFIDES
SULFUR COMPOUNDS
TESTING
TRANSITION ELEMENTS