voestalpine Stahl GmbH has given Primetals Technologies the final acceptance certificate for the Seku 3.1 secondary dedusting system in the Linz plant. The system was constructed during the course of voestalpine's SEK MET 4 project and cleans up to 700,000 actual cubic meters of off-gas from secondary metallurgical facilities per hour. The expected clean gas dust content is less than one milligram per standard cubic meter, which is considerably less than the legally prescribed limit. The system was ordered from Primetals Technologies in the third quarter of 2014 with the aim of further increasing the capture rate and the separation of dusts in downstream metallurgy.
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 are combined into seven groups for the ladle furnaces, the alloying groups, the conditioning stand and the bunker extraction. A 2,300 kilowatt, induced-draught, speed-controlled fan enables the extraction capacity to be adjusted to match changing operational conditions. In normal operation, the system cleans 610,000 working cubic meters of off-gas per hour at temperatures up to 130 °C. The maximum capacity is 700,000 cubic meters per hour. The dust is separated by bag filters with a total surface area of almost 9,900 square meters. The expected clean gas dust content is less than one milligram per standard cubic meter. The filters are equipped with compressed-air cleaning developed by Primetals Technologies. This enables the bags to be cleaned gently but effectively with economical use of the compressed air. 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 to either a silo or the granulation plant.
The scope of delivery also included the mechanical and electrical equipment, the instrumentation and control equipment, and the visualization. Primetals Technologies was also responsible for the engineering, installation and commissioning of the plant. SGS Industrial Services from Dorf an der Pram, Austria, performed the mechanical assembly work such as structural steel work, piping, raw and clean gas ducts, clean-gas stack, fan system and reconnection work on existing system sections.