Patent EP-2581462-A1 (EP)
Inventor: BRAUN DIETER
IPC: C21C5/46
Filed: 2011-10-10
Abstract: The blast lance comprises an outer jacket (8), which extends along a blast lance longitudinal axis, where an oxygen guide runs within the outer jacket and comprises an oxygen exit (14) for emerging oxygen (6) at a blowing end of the lance. The oxygen exit is fed over an oxygen supply connection into the oxygen guide. A combustible gas guide runs within the outer jacket and comprises a number of combustible gas exits for emerging a combustible gas at the blowing end of the blast lance. The combustible gas exits are fed over a combustible gas supply connection into the combustible gas guide. The blast lance comprises an outer jacket (8), which extends along a blast lance longitudinal axis, where an oxygen guide runs within the outer jacket and comprises an oxygen exit (14) for emerging oxygen (6) at a blowing end of the blast lance. The oxygen exit is guided over an oxygen supply connection into the oxygen guide. A combustible gas guide runs within the outer jacket and comprises combustible gas exits for emerging a combustible gas at the blowing end of the blast lance. The combustible gas exits are guided over a combustible gas supply connection into the combustible gas guide. An ignition device: is arranged in the blast lance; comprises an ignition tip for igniting a combustible gaseous mixture; and is movable between its extended position and withdrawn position. The firing tip is affected in the extended position to a mixing region, in which the oxygen supplied to the oxygen exit and the combustible gas withdrawing at the combustible gas exits are mixed to the combustible gaseous mixture. The ignition device is withdrawn in the withdrawn position into a save area, in which the ignition device is protected before splashing a metal melt. The ignition device extends parallel to the blast lance longitudinal axis, and is parallely displaceable to the blast lance longitudinal axis. The firing tip of the ignition device extends in the extended position over the blowing end of the blast lance. The oxygen guide comprises a widening region. The ignition device is arranged beside the oxygen guide and extends in the extended position into the widening region. One of the combustible gas exits is arranged in the oxygen guide so that a mixing region is arranged within the oxygen guide. A passage for guiding the ignition device is opened over a lateral recess to the mixing region, and the firing tip of the ignition device is arranged in the extended position in an area of the recess. The firing tip of the ignition device is withdrawn in the withdrawn position from the mixing region. The ignition device: is flexed; helically extends around an ignition device longitudinal axis that runs parallel to the blast lance longitudinal axis in a constant distance to blast lance longitudinal axis; is formed in an arc-shaped manner; and is designed as an ignition lance, which generates spark ignition tip. An ignition apparatus is connected to the ignition lance, via a cable (26), for providing voltage pulses required to generate the ignition spark. The ignition apparatus is designed as capacitor-supply semiconductor ignition device. The save area is covered, in the withdrawn position of the ignition device to the mixing region, by a cover device.