Thermochemical recuperation by steam methane reforming as an efficient alternative to steam injection in the gas turbines

Abstract

Improving the energy efficiency of gas turbines is an extremely important task of the world energy industry. This paper presents the results of thermodynamic analysis of a gas turbine unit with thermochemical exhaust heat recuperation by steam methane reforming (chemically recuperated gas turbine — CRGT). The thermochemical exhaust heat recuperation systems consist of a reformer, a steam–methane mixture preheater, and a steam generator. The main goal of this paper is comparing CRGT efficiency with the efficiency of a gas turbine unit with steam injection (STIG). To calculate the recuperated heat in a reformer, the thermodynamic analysis of steam methane reforming was performed via Gibbs free energy minimization method. Both thermodynamic cycle and reforming analysis were performed via Aspen HYSYS. The analysis was performed in the temperature range of working fluid at a turbine inlet (Tin) of 800–1300 °C and the steam-to-methane ratio of 1, 2, 3 (mol-to-mol). The results showed that thermochemical exhaust heat recuperation can be considered as an alternative to steam injection in gas turbines. The efficiency of CRGT is higher than the efficiency of STIG for the same steam-to-methane ratio. With increasing in Tin the efficiency of CRGT is increasing. The efficiency of STIG and CRGT at Tin=1300 °C for a steam-to-methane ratio of 3 is 37.4% and 47.3%, respectively.