SMS Mevac GmbH (Essen, Germany):

Dorstewitz F., Dr. Eng., Head of Processing Equipment

Tembergen D., Mag. Eng., Head of Metallurgy, E-mail: dieter.tembergen@sms-mevac.com

The following article describes the general technical requirementsplaced on vacuum pumps for secondary metallurgical plants.Vacuum treatment of liquid steel takes a prominent position amongthe various secondary metallurgical processes due to its versatile nature,especially in the production of high-quality steel grades. Forgeneration of the required medium vacuum, efficient state-of-the-artsecondary metallurgical plants use pump systems consisting of steamejector pumps or mechanical vacuum pumps for the vacuum treatment of steel. To decide on which of these systems to use, it is necessary to also consider optimization of the overall system including anyauxiliary equipment, in addition to the metallurgical task and the specific operating costs of the operating company. Distribution of vacuumfacilities of VD and RH type worldwide in accordance with heat sizeduring 1990–2010 is shown. Operation of the single-vessel RH plant at ArcelorMittal Eisenhüttenstadt, twin-tank VD facility Shanghai No. 1 are observed in this paper. Typical pressure reduction in a VD facility for degassing and typical pressure reduction for a steel grade to be decarburized in RH facilities are compared. Gas quantities arising for selected standard metallurgical operation (VD, VOD, RH, RH-O) and intake capacities of the steam injection vacuum pump and mechanical vacuum pumps at a pressure of 0.67 mbar are analyzed, including conversion factors for individual gases. Required plant components and auxiliary equipment as a function of the metallurgical process and of the vacuum pump system are presented. Operating and investing costs for using mechanical and steam-ejection vacuum pumps are estimated.

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