Intelligent Decision Support System for Alumina Point Feeder Inspection and Tending

I prosjektet har vi identifisert og testet instrumenter for avbildning, 3D-målinger, spektroskopi, temperatur og termografi. Målet med testene har vært å finne hvilke målinger som er best egnet i videre utvikling mot prosjektets hovedmål. Testene har vist hvilke instrumenter som er best egnet for å vurdere ulike problemtyper ved matehullene. En plattform (hardware og software) er laget som grunnlag for videre utviklingsarbeid. Problemstillingen ble delt opp i ulike underoppgaver som skulle løses enkeltvis. Først var hovedfokus på å oppdage kladding på hammeren som lager hull i krusten. Til dette brukte vi kamerateknologi kombinert med laser. Denne teknologien ble også brukt i utviklingen for å måle oksidnivå og om det er åpning til badet.

Aluminium is produced by electrolysis of aluminium oxide (alumina). Alumina as powder is added to the electrolyte automatically. This is done by a socalled point feeder technology, using a pneumatic hammer breaking the frozen top crust. The alumina is fed to the feeding area in a closed system. Process disturbances may upset the feeding operation leading to reduced productivity from loss in current efficiency and increased emissions of fluorides, dust, PAH and climate gases. It is imperative to have a clo se follow-up of the feeding area in order to discover any deviations at the earliest possible time to take corrective actions. Both the follow-up in the form of daily manual inspections and corrective actions are done by operators. The types of corrective actions are defined based on how the condition differs from the standard. At the Lista plant, there are 276 cells having two point feeders each. To inspect all point feeders, operators have to move a total distance of 6 km. Hence routine inspections a re costly and time consuming. The point feeders should be inspected several times per day. Feeders with operating problems require additional inspections and corrective actions. The aim of the project is to develop a tool which can perform this inspecti on automatically, and determine the condition of the point feeder area and corrective actions. This tool will in time be mounted on a robot moving from cell to cell. The robot will obtain access to the closed feeding area. An automatic system for point feeder inspection will enable a much more frequent, accurate and objective inspection, compared to the current situation. This will lead to a more stable operation with higher productivity, less emissions and less maintenance.