Operational results of a new blast furnace gas injection system

The blast furnace gas injection project at voestalpine. Stahl GmbH in Linz focuses on a further development of the utilisation of gases available in an integrated metallurgical plant from the coke production and the BOF process. They shall substitute alternative reducing agents like heavy fuel oil which are purchased from out-side sources. The injection of reducing gases into the blast furnaces results in a greater flexibility in gas utilisation, as gas volumes can be moved between blast furnace and power plant. The blast furnace gas injection project includes a new coke oven gas line between coke oven plant and blast furnace area, a mixing station for the gases, a screw compressor to compress up to 35 000 m(3) (S.T.P.)/h gas to 5 bar, a pipe and control system in the BF area and the injection technology at the tuyere level. The commissioning started in the second quarter of 2002 with the replacement of heavy fuel oil by coke oven gas (COG) during a period of high level hot metal production. A successful change of,alternative reducing agents from 70 kg/t HM heavy fuel oil to 12 500 m(3) (S.T.P.)/h (50 kg/t HM) COG and up to 20 kg/t HM heavy fuel oil at BF 5 and 6 were performed.