A chemical plant and operating method therefor; the chemical plant comprises a steam turbine having a shaft, a first pressure turbine stage and a second pressure turbine stage, each being arranged on the shaft and being connected in series in terms of the steam process; steam for driving the steam turbine is obtained from a reactor plant, said reactor plant producing a hydrogen-containing substance from a carbon-containing energy-carrier stream; the steam is heated in an overheating step before being supplied to the second pressure turbine stage; the steam turbine has a third pressure turbine stage which is arranged on the shaft and which is connected between the first pressure turbine stage and the second pressure turbine stage in terms of the steam process; and the steam passes through the overheating step after exiting the third pressure turbine stage.