The preliminary cleaning stage for a dust extraction installation for blast
furnace gas is comprised of a large-sized cyclone which comprises a
vertical pressurized tank. A gas furnace gas line arriving from the blast
furnace is connected to an axial delivery device situated at the upper end
of the pressurized tank. The delivery device is configured such that it
introduces the blast furnace gas into the pressurized tank in an axial
direction. A swirl device with guide vanes is positioned below the axial
delivery device and causes the blast furnace gas which is axially
introduced into the pressurized tank to swirl about the axis of the
pressurized tank.