Primary steelmakers and metalcasters have more process technology in common than is commonly understood, and the recent attention on collecting particulate emissions is a reminder of the need to take a comprehensive view of technological developments.
Austrian steelmaker voestalpine Stahl GmbH has adopted a number of process technologies worthy of metalcasters’ attention, the latest being system for capturing particulate in the emissions of combustion gases. Recently, voestalpine Stahl gave its final acceptance certificate to Primetals Technologies, the developer of the Seku 3.1 secondary dedusting system.
The system, part of voestalpine's SEK MET 4 project, is able to clean up to 700,000 m3/hour of off-gas from secondary metallurgical processes (ladle metallurgy, vacuum degassing.)
In the resulting “clean gas,” the expected dust content will be less than one milligram per standard cubic meter (< 1mg/m3), which is described as “considerably less than the legally prescribed limit.”
The system was ordered from Primetals Technologies in during Q3 2014, in an effort to raise the capture rate and the separation of dusts in the metallurgical stages downstream from the melt shop, including ladle refining and pouring .
The new secondary dedusting system has a total of 24 new and two existing extraction points, as well as an existing alloying group with multiple extraction points, which combine into seven groups for the ladle furnaces, the alloying groups, the conditioning stand and the bunker extraction. A 2,300 kilowatt, induced-draft, speed-controlled fan makes it possible to adjust the extraction capacity to match changing operational conditions.
In normal operation, the system cleans 610,000 m3 of off-gas per hour at temperatures up to 130°C. The maximum capacity is 700,000 m3/hour. The dust is separated by bag filters with a total surface area of almost 9,900 m2. The expected clean gas dust content is less than one milligram per standard cubic meter.
The filters are equipped with a compressed-air cleaning capability developed by Primetals Technologies, which means the bags can be cleaned gently, but effectively and economically. The electric motor of the induced-draft fan is partially enclosed to minimize noise emissions. Troughed chain conveyors and pneumatic conveyors carry the separated dust either to a silo or the granulation plant.
Primetals Technologies was responsible for the engineering and installation, and also supplied the mechanical and electrical equipment, the process control platform, control instruments, and the visualization system.