MHD/GAS TURBINE/STEAM TURBINE TRIPLE COMBINED CYCLE WITH THERMOCHEMICAL HEAT RECOVERY

An MHD/Gas/Steam combined cycle driven by coal gasified gas were studied where the gasification heat was supplied primarily from the MHD exhaust. As the most influential component, the synthetic gasoxygen fired MHD generator was investigated in detail. Without considering heat losses and electrical consumption, a 65 % plant thermal efficienciy was obtained with 25 % MHD enthalpy extraction and 45 % synthetic fuel partition to the MHD cycle. With inclusion of heat losses and power consumption, a 52.1 % efficiency was still demonstrated for a 1000 MWth scale MHD thermal input. The flow in the MHD channel was highly interactive with the magnetic field. The channel length and the volume required for given pressure drop were considerably reduced in comparison with those of the direct coal fired channel. More than 50 MWe/m3 power density could be attained under the wall stresses well below the critical values. We showed that the present cycle surpassed the direct coal fired MHD/ Steam conbination with respect to the efficiency and the C02 emission consuming the same amount of coal.