Plant combination for producing steel and method for operating the plant combination

A plant complex for the production of steel, comprising:

• a blast furnace for producing pig iron;
• a converter steel mill for producing crude steel;
• a gas-conducting system for gases that occur in the production of pig iron and/or the production of crude steel;
• a power-generating plant for electricity generation;
• a hydrogen-producing plant;
• and
• a chemical plant having a plurality of small units arranged in parallel that are individually switched on or off;
• and
• a closed loop control system;
• wherein:
• the power-generating plant is designed as a gas-turbine power-generating plant or gas-turbine and steam-turbine power-generating plant;
• the power-generating plant is operated with a gas that comprises at least a partial amount of blast-furnace top gas that occurs in the production of pig iron in the blast furnace and/or a partial amount of the converter gas that occurs in the converter steel mill;
• the chemical or biotechnological plant is connected to the gas-conducting system and arranged in parallel with the power-generating plant with respect to the gas supply;
• the hydrogen-producing plant is an electrolysis plant for the electrolysis of water and is connected to the gas-conducting system by a hydrogen-carrying line;
• the gas-conducting system comprises an operationally adjustable gas diverter for dividing and controlling the streams of gas that are fed to the power-generating plant and the chemical or biotechnological plant;
• the gas-conducting system further comprises, upstream of the gas diverter in the direction flow, a mixing device for producing a mixed gas comprising blast-furnace top gas and converter gas;
• the gas diverter adjusts an amount of the mixed gas fed to the power generating plant and the chemical plant when a price for externally obtained electricity reaches a predetermined threshold;
• the chemical plant comprises a plurality of small units arranged in parallel which can be individually switched on or off;
• and
• the closed loop control system establishes an alternating operation of the power generating plant and the chemical plant.