Conceptual design of a large coal-fired stationary Stirling engine

A conceptual design is presented for a stationary coal-fired Stirling engine sized for power generation in the 400-2200 kW range, suitable for commercial/industrial cogeneration applications. The proposed power plant consists of one or more 500-hp Stirling engines, a coal combustion system and a heat transport system, along with an electric generator and waste heat recovery equipment of conventional design. The U-form engine is placed on top of a fluidized bed combustor, with the crankshaft above the cylinders and heater head, and heat is conveyed from the combustor to the engine heater-head by a two-stage sodium heat pipe. Projections of system performance for the case of an engine heater head temperature of 720 C, engine mean helium pressure of 15 MPa and engine speed of 900 rpm with waste heat utilization result in an overall efficiency of 79%. Based on a system capital cost of $950-1500/kW(e), an electric power generation cost of $0.093/kWh is estimated which may be reduced by waste heat utilization.