Comparative thermodynamic and economic analysis of a conventional gas-steam power plant with a modified gas-steam power plant

Abstract

This paper presents a thermodynamic and economic comparative analysis of a conventional gas-steam power plant with a modified gas-steam power plant. The modification involves replacing the gas turbine present in the conventional power plant with a High Temperature Gas-cooled Reactor (HTGR) and a turboexpander. In the Joule cycle modified power plant, the circulating medium is helium, while in the conventional power plant it is the exhaust gas produced from the combustion of natural gas. The results obtained show that the innovative dual-circuit gas-steam power plant with a high-temperature HTGR nuclear reactor and TE turboexpander has significantly higher economic efficiency than a conventional gas-steam power plant. This is despite the fact that the unit capital expenditures for a power plant with HTGR and TE are many times higher (about 8 times) compared to those for a conventional gas-steam power plant. Increasing the temperature T3 of the outlet helium from the TE above the value of T3opt= 709.1K with temperature T2 = 1300 K, is possible by reducing the compression ratio p1/p0. This will result in a significant increase in the energy efficiency of the gas-steam power plant ηG-S and of its output NG-S=NTE+NST. Increasing the temperature T3 is advantageous also for economic reasons.