SGER: Analysis of Exterally-Sustained MMHD Processes for Enhanced Electrical Power Generation Efficiency Using Gas from Reformed Coal

Princeton University, Princeton NJ

Investigators

Abstract

0120617 Miles This research program will explore the potential of electron beam sustained MHD power generation for enhancing the electrical efficiency of advanced ground based coal fired power plants. In conventional MHD, the high temperatures that are required (even with seeding) lead to significant oxides of nitrogen production. The electron beam sustained MHD has the capability of operating at relatively cool temperatures, without the need for seed material to be added to the flow. The lower temperature allows of a variety of new, possibly high efficiency, low polluting approaches to be explored, the most desirable of which would be the utilization of the high flame temperature to drive a high velocity, low temperature supersonic flow with rapid quenching of the formation of oxides of nitrogen through a supersonic expansion. The active control of the conductivity that electron beam sustained MHD affords also opens the door to advanced methods of control for MHD processes, particularly to suppress parasitic current paths and permit operation in dynamic modes that might allow for improved performance. The electron beams enter the MHD channel along magnetic field lines, and the conductivity is sustained by the secondary electrons that are produced. To suppress the electron loss rate, the channel must be operated at low pressure. For ground based facilities, this means the flow will need to be supersonic. Since the presence of coal slag along the walls will cause difficulty with electron beam transmission into the MHD channel, the main focus of the research will be to examine the coupling of the electron beam MHD concept together with new membrane technology gasification processes that convert coal to hydrogen and CO2. MHD has the potential for more efficient electrical conversion of hydrogen through combustion at a temperature higher than is possible with turbine inlet temperature limits. This research explores the possibility of e-beam sustained MHD for high efficiency conversion by independently controlling the combustion temperature through combustion in a supersonic nozzle, the formation of oxides of nitrogen through kinetic rate differentials, and the optimization of the conductivity profiles. Modeling indicates that the cost of the electron beams can be relatively small if the electron loss rate is minimized.