Technologies for increasing CO2 concentration in exhaust gas from natural gas-fired power production with post-combustion, amine-based CO2 capture

Enhanced CO2 concentration in exhaust gas is regarded as a potentially effective method to reduce thehigh electrical efficiency penalty caused by CO2 chemical absorption in post-combustion capturesystems. The present work evaluates the effect of increasing CO2 concentration in the exhaust gas of gasturbine based power plant by four different methods: exhaust gas recirculation (EGR), humidification(EvGT), supplementary firing (SFC) and external firing (EFC). Efforts have been focused on the impacts oncycle efficiency, combustion, gas turbine components, and cost. The results show that the combined cyclewith EGR has the capability to change the molar fraction of CO2 with the largest range, from 3.8 mol% toat least 10 mol%, and with the highest electrical efficiency. The EvGT cycle has relatively low additionalcost impact as it does not require any bottoming cycle. The externally fired method was found to have theminimum impacts on both combustion and turbomachinery.NOTICE: this is the author’s version of a work that was accepted for publication in Energy. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Energy, [VOL 36, ISSUE 2, 2011]