Heat and power integration for hydrogen-fuelled Combined Cycle Gas Turbine (CCGT)

Abstract

Integrated Gasification Combined Cycle (IGCC) is a technology for power generation in which the feedstock is partially oxidized to produce syngas (a gas mixture containing mainly hydrogen and carbon monoxide). In a conventional IGCC design, the syngas is purified for dust and hydrogen sulphide (H 2 S) removal and then sent to a Combined Cycle Gas Turbine (CCGT) for power generation. Carbon capture technology is expected to play a significant role in the coming decades for curbing the greenhouse gas emissions. IGCC is one of the power generation technologies having the highest potential to capture CO 2 with low penalties in efficiency and cost. In a modified IGCC design for carbon capture, syngas is shifted to maximize the hydrogen level in the syngas and to concentrate the carbon species as CO 2 than can be later captured. After CO 2 and H 2 S capture in a pre-combustion arrangement, the hydrogen-rich syngas is used in a CCGT for power generation. This paper investigates the main differences in term of heat and power integration between a syngas-fuelled CCGT and a hydrogen-fuelled CCGT. The coal and biomass-based IGCC case study investigated in the paper produces around 400 MW electricity with 90 % carbon capture rate (main design data). The cases were simulated using ChemCAD to produce input data for heat and power integration study of the CCGT section (integrated with rest of the plant units). The combined cycle configuration considers the use of one gas turbine (M701G2 type of Mitsubishi Heavy Industries) and one steam turbine with a steam cycle having three pressure levels and one reheat (for MP steam). Heat and power integration analysis optimizes the steam flows generated in HRSG for maximizing the power production. Influence of ancillary power consumption in the both cases (hydrogen and syngas-fuelled CCGT) is discussed for evaluation of efficiency penalty associated with carbon capture and storage (CCS).