Conceptual design of a coal-fired MHD retrofit plant: Quarterly report, January 1988--March 1988

The objective of the systems analysis task is to define an optimized set of operating conditions for the Scholz MHD Retrofit Plant. These operating conditions must satisfy the prescribed system requirements and be consistent with the overall objectives of this conceptual design study: to demonstrate the technical and economic viability of an MHD system operating within an electric utility environment. Thus, the Retrofit Plant must be both efficient and economically attractive. Parametrics studies resulted in an optimized components arrangement for the MHD System. Using this component arrangement, a series of sensitivity studies were completed. These studies evaluated twenty-five operating conditioning covering oxygen enrichment levels from 32 to 40% and combustion pressures between 4 and 8 atmospheres. The criteria used to identify the reference operating conditions are relative plant performance and relative cost-of-electricity (COE). Plant performance is defined as the thermal input to the plant divided by the net ac output. This accounts for all possible losses, including the dc to ac power inversion loss. To ensure that all twenty-five cases were evaluated on a similar basis, the following operating paramaters were held constant: primary combustion of 0.88 stoichs; oxidant preheated to 1450/degree/F; secondary combustion at 1.05 stoichs; secondary air preheatedmore » to 600/degree/F; gas velocity exiting MHD generator at Mach 1.0; feedwater available at 1080 psia, 425/degree/F; required steam flow of 460,000 lb/hr at 875 psia, 908/degree/F; and combustion gas temperature at 400/degree/F exiting the bottoming cycle. The most efficient cases were found at intermediate combustion pressures of 6 and 7 atmospheres with intermediate oxygen enrichment levels at 36 to 38%. To determine the most attractive operating conditions based on economics, a cost-of-electricity was calculated for each of the twenty-five cases. 4 figs., 4 tabs.« less