On the synergism between the 'OMACON' liquid metal MHD and the FBC technologies

A preliminary study is carried-out to assess the feasibility of improving the thermodynamic performance of bubbling fluidized bed combustion power plants by incorporating in it the OMACON liquid metal MHD energy conversion technology. It is found that by virtue of its isothermal expansion, the OMACON Rankine cycle offers a better match to the FBC temperature dependence of heat supply than the turbine Rankine cycle. The resulting increase in the energy conversion efficiency is found to approach 10%. Moreover, as the steam superheating and reheating can be done in direct contact with the OMACON liquid metal, the use of the OMACON technology can enable nearly 20% reduction in the overall heat-exchangers surface area for transferring the FBC heat to the cycle. In addition, due to the larger amount of work done per unit mass of steam which goes through the cycle, the capacity of the feedwater pumps, heaters and water treatment systems needed for the OMACON FBC plant is estimated to be smaller than that of conventional FBC plants by up to 40%. Additional increase in the OMACON cycle efficiency is expected by further optimization and by going to higher cycle pressures and temperatures.