Performance of IGFC With Exergy Recuperation

Abstract

The Integrated coal Gasification Combined Cycle (IGCC) is considered to be a very clean and efficient system for coal-fired power generation. And given the development of 100 MW-scale solid oxide fuels cells (SOFCs), the integrated coal Gasification Fuel Cell combined cycle (IGFC) would be the most efficient coal-fired power generation system. However, more energy efficient power generation systems must be developed in order to reduce CO2 emissions over the middle and long term. Thus, the authors have proposed the Advanced Integrated coal Gasification Combined Cycle (A-IGCC) and Advanced IGFC (A-IGFC) systems, which utilize exhaust heat from solid oxide fuel cells (SOFCs) and/or gas turbines as a heat source for gasification (exergy recuperation). The A-IGCC and A-IGFC systems utilize a twin circulating fluidized bed coal gasifier consisting of three primary components: a pyrolyzer, steam reformer and partial combustor. The temperature of the steam reformer is 800 °C, and that of the partial oxidizer is 950 °C. Since the syngas, produced by pyrolysis and the reforming process involving volatile hydrocarbons, tar and char, contains carbon monoxide and hydrogen, the A-IGCC technology has considerable potential for higher thermal efficiency while utilizing low-grade coals. The coal types utilized in the study were bituminous Taiheiyo, sub-bituminous Adaro and Loy Yang coal. Milewski’s formula was used to model the circuit voltage of the SOFC. Cool gas efficiency increases, in order, from Taiheiyo coal to Adaro coal to Loy Yang coal. The A-IGFC system has the potential to achieve high thermal efficiency using various coals, with Loy Yang coal achieving the highest thermal efficiency. However, the drying process for Loy Yang and Adaro coal is an important issue.