Conceptual Design of a Pulverized Coal Furnace for a Utility Size Closed-Cycle, Gas-Turbine Power Plant
A study has recently been completed for the Department of Energy on the conceptual design of coal-fired, closed-cycle, gas-turbine power plants that operate at high turbine-inlet temperatures and use air as the cycle fluid. This paper describes the design of one type of heater system for such a power plant — a pulverized coal furnace. Designs are presented for a 1550 F (843 C) turbine inlet temperature cycle that utilizes metallic superalloy heat exchanger tubes and a 1750 F (954 C) turbine inlet temperature cycle that utilizes ceramic heat exchanger tubes. The heaters consist of two sections — a radiant section where heat is transferred primarily by radiation from the pulverized coal luminous flame, and a convective section where heat is transferred primarily by forced convection from the nonluminous combustion gas. To maintain flame stability in the furnace, a minimum power density criterion must be met. This requires modularization of the radiant heaters.