This study aims at investigating different pre-combustion CO2 capture options based on gasification of low grade coals. Two main IGCC process schemes with different CO2 capture technologies are presented and their performance is evaluated.
The first scheme is based on HTW (High Temperature Winkler) gasification process coupled with two water gas shift reactors at high and low temperature and a Rectisol unit for H2S removal and CO2 separation. The HTW gasifier was firstly developed for the production of chemical synthesis gases from lignite instead of electricity, however today the same technology can be used for electricity production in IGGCs power plants with or without CO2 capture utilizing commercial available technology.
The second process scheme is based on a novel steam gasification process with calcined limestone where in-situ CO2 capture and steam reforming are taken part in a single reactor. CO2 is separated by the exothermic reaction with CaO which also provides the necessary heat for gasification reactions. Afterwards CO2 is released in a separate reactor and CaO is produced which is continuously recycled within the process. The principle of the second process scheme examined was firstly introduced in the mid sixties targeting for the production of a hydrogen rich gas and nowadays is gaining interest in the framework of the implementation of CO2 capture technologies in fossil fuel power plants.
In this study we present possible plant configurations for the selected gasifications technologies integrated to a modern gas turbine combine cycle and we perform detailed simulation with Aspen Plus software of alternative CO2 capture scenarios