Study of Coal Based Technologies as Part of the National Energy Strategy Support Services. Final Report. Volume 2, Part 1

摘要

This volume considers fossil-fuel power plants and fluidized bed combustors. In a conventional coal-fired power plant, superheated steam is supplied at high pressures from a steam generator to a steam turbine whose thermodynamic energy is converted to mechanical energy. Electricity is generated from the expansion of steam in the steam turbine. The use of coal requires the implementation of emission controls to meet environmental standards. Figure 1 is a simplified flow schematic of a coal fired steam plant. Variations to the basic cycle are possible without changing the basic thermodynamics. Fluidized bed combustion involves the burning of coal in a fluid bed containing a crushed sulfur acceptor such as limestone or dolomite. The temperature of the combustion process is controlled by heat extraction from the bed and/or by controlling the fuel-air ratio in the bed. It is necessary to maintain the bed temperature below the coal ash softening temperature and in a range that would provide efficient capture of sulfur dioxide by the sulfur acceptor. With this process it would be possible to capture sufficient sulfur products to permit the use of high-sulfur coals and still meet the current federal Environmental Protection Agency limits for emissions. (ERA citation 10:016079)