Gas turbine technology for syngas/hydrogen in coal-based IGCC
AUTHOR: Irene M. Smith
DATE: October 2009
Gas turbines have been developed for burning natural gas and fuel changes to burn syngases affect operational performance and emissions. The composition of syngas varies widely and is mostly H2 and CO rather than the CH4 of natural gas. Carbon removal increases the H2 content with its high flame speed, high flame temperature and wide flammability range. The compressor, fuel system and turbine (expander) need some modifications. Improvements are required in thermal barrier coatings and film cooling designs. The combustor is the part of the gas turbine which is most affected by burning synfuels/H2. Diffusion and pre-mix combustors, hybrid designs, as well as catalytic combustors are being developed to burn high H2 synfuels at firing temperatures >1400 degree C. The aim is to develop fuel flexible, low NOx combustors over the next few years, with minimal need for diluent. Current commercial and demonstration IGCC plants using coal have gas turbine firing temperatures of up to 1300 degree C on syngas, with net plant efficiency of about 40->43%. Future IGCC plants will require CO2 reduction, probably with zero air integration to reduce operating complexity. Tradeoffs between efficiency, reliability, availability and maintainability (RAM) need to be optimised and then validated on the next generation of demonstration plants, due to start this year.