u00b0 c is transferred to a heat exchanger for steam creation 60 the steam thus generated is transferred to a turbine not shown and a generator not shown to produce electricity the cooled gas is then led back via a pipe 62 in a closed loop system to the fan 52 at this temperature level of about 700 u00b0 c thermodynamic cycle processes for power generation operate at best efficiency furthermore this temperature level offers best flexibility and efficiency for direct heat recovery since the slag gas heat exchanger 44 runs continuously efficient electricity generation is possible in the present embodiment both the material and gas streams enter and leave the heat exchanger continuously the material and gas handling are however decoupled gas leakage is no longer an issue as the concerned heat exchanger subunit is decoupled from the gas flow during charging and discharging accordingly sealing of the heat exchanger subunits can easily be obtained with sealing flaps as no material is in movement inside the exchanger during the gas flow due to the decoupling of the gas and material flows the sealing of the heat exchanger is simplified and dust emissions into the environment are eliminated respectively minimized the sealing of the heat exchanger subunits during the cooling operation eliminates the risk of gas leakage and thus the effect of u201c sand blasting u201d caused by slag particles entrained by the escaping gas is no longer an issue this results.