Stability analysis of MHD disk generators and application to power systems with CO2 recovery

Preliminary design and stability analyses of magnetohydrodynamic (MHD) disk generators have been carried out. These are used in electric power-generation systems with CO2 recovery. Inflow disk channels show better performance than outflow disk channels. An inflow channel with supersonic flow shows an enthalpy extraction ratio of 20.2% when the thermal input is 1100 MW and the magnetic field is 8 T. The calculated enthalpy extraction is 23.5% with 2000 MW and 10 T. A stability analysis has shown that it is possible to stabilize the open-cycle disk channels, although the channels tend to become unstable at the exit region when they are operated with 10 T. Cycle analyses have been carried out for an electric power system in which coal is burnt with 95% oxygen and CO2 is recovered as liquid. A high cycle efficiency of 43% (higher heating value, HHV) can be obtained for a thermal input of about 1000 MW and magnetic field of 8 T while 46% HHV results from the system with about 2000 MW and 10 T, even when the power required for CO2 liquefaction is considered.