Integrated Gasification Combined Cycle
Coal, petroleum coke and other feedstocks can be used to produce electricity from gasification, commonly referred to as Integrated Gasification Combined Cycle (IGCC). In general, coal and petroleum coke have been used with IGCC, but biomass has also been blended in with these feedstocks.
An IGCC power plant combines the gasification process with a “combined cycle” power block (consisting of one or more gas turbines and a steam turbine). Clean syngas is combusted in highly efficient gas turbines to produce electricity. The excess heat from the gas turbines and from the gasification reaction is then captured, converted into steam, and sent to a steam turbine to produce additional electricity
In IGCC-where power generation is the focus, the clean synthesis gas is combusted (burned) in high efficiency gas turbines to generate electricity with very low emissions. The gas turbines used in these plants are similar to jet engines and are slight modifications of proven, natural gas combined-cycle gas turbines that have been specially adapted for use with syngas applications. For IGCC plants that include carbon dioxide capture, these gas turbines are adapted to operate on syngas with higher levels of hydrogen. Although modern state-of-the art gas turbines are commercially available for this “higher hydrogen” syngas, additional development work is ongoing to develop the next generation of more efficient turbines ready for carbon dioxide capture-based IGCC.
The heat recovery steam generator (HRSG) captures heat in the hot exhaust from the gas turbines and uses it to generate additional steam that is used to make more power in the steam turbine portion of the combined-cycle.
In most IGCC plant designs, steam recovered from the gasification process is superheated in the HRSG to increase overall efficiency output of the steam turbines, hence the name Integrated Gasification Combined Cycle, which includes a gasification plant, two types of turbine generators (gas and steam) and the HRSG is efficient and clean.