Final report on the PNL program to develop an alumina sensor. Sensors Development Program

摘要

An alumina concentration sensor was required to ensure safe operating conditions for cermet inert anodes that were under development at the Pacific Northwest Laboratory (PNL)(a) for the electrolytic production of aluminum metal. The Sensors Development Program at PNL was conducted in response to this need for an alumina sensor. In all, eight different approaches to developing an alumina sensor were evaluated as part of this program. Each approach sought to correlate alumina concentration either to some spectral, physical, or electrical property of the molten electrolytic, or alternatively, to some operational characteristic of the reduction cell such as the integrity of the cermet anodes or the electrical noise generated by them during cell operation. The studies on electrical noise were performed using a large number of digital signal analysis (DSA) methods. There were two primary requirements for success for an alumina sensor to be used in conjunction with cermet anodes: (1) adequate sensitivity to alumina concentration at concentrations close to saturation, and (2) ease of use in an industrial setting. After numerous laboratory experiments as well as field studies in some cases, it was concluded that none of the approaches sufficiently satisfied the two criteria to serve as the basis for an alumina sensor. If further work is to continue in this area, it is recommended that the research focus on altemative DSA approaches, primarily because DSA methods would be so easy to use in an industrial environment. Due to the lack of correlation using DSA in the present work, however, it is recommended that altemative strategies for data collection and analysis be used in any further development activities.