Investigation of Alternative Strategies for Integrating Post-combustion CO₂ Capture to a Natural Gas Combined Cycle Power Plant

Abstract

With increasing urgency for global action toward climate change mitigation, this study is undertaken to evaluate integration options for post-combustion CO 2 capture (PCC) on gas-fired power plants. High-fidelity models of a natural gas combined cycle power plant, a PCC plant, and a CO 2 compression train are integrated for a 90% CO 2 capture level. Three options to provide steam for solvent regeneration are explored: extracting steam from the intermediate-pressure (IP)/lowpressure (LP) crossover, using a gas-fired package boiler, and extracting steam from the LP drum. The effect of pressure losses because of steam extraction, a factor ignored in previous analyses, is also considered. The integrated plant net efficiency is 47.8, 40.4, and 44.9%, respectively, for the aforementioned scenarios. Next, supplementary firing of gas turbine exhaust is employed to generate an ample amount of steam to preserve plant net output under a sliding pressure scenario and meet solvent regeneration requirements. It is observed that the net plant efficiency converges to a value of 43.5% for the options considered.

Making gas‐CCS a commercial reality: The challenges of scaling up

“…Supplementary firing has been suggested as an option to facilitate CO 2 capture in NGCC power plants . It consists of burning additional fuel after the gas turbine using the oxygen still present in the exhaust gas as the oxidizer, as depicted in Fig.…”

“…This is the case of supplementary firing systems integrated with exhaust gas reheating or with exhaust gas recirculation, and the combination of supplementary firing, exhaust gas reheating and recirculation, together with a supercritical HRSG design . Further advanced configurations with exhaust gas recirculation and different options for the integration of the supplementary firing NGCC and the amine capture plant can be found elsewhere . However, all these configurations come at the expense of an increase in complexity and reduced flexibility of the NGCC power plant, and further techno‐economic analysis is required in order to quantify the actual advantages of these systems.…”

“…This, in turn, can result in significant energy and cost reductions -particularly in the capital and operational expenditure (CAPEX and OPEX) -and contribute to the deployment of gas-CCS. For this purpose, modifications to existing systems, alternative processes and new configurations have been proposed, including the use of supplementary firing, 8,[12][13][14]20,21 exhaust gas recirculation, 8,15,16,22,23 selective exhaust gas recirculation, 17,24 and humidified cycles. 8,[17][18][19][25][26][27][28] Also, advancements have been made for the development of oxy-fired gas turbine cycles, 15,[29][30][31][32][33][34] which are seen as a potential alternative to post-combustion capture systems.…”

“…1 is the maximum temperature allowed in the HRSG, which is associated with material resistance. The maximum temperature of the flue gas entering the HRSG is usually around 800°C, 13,20 although it can be increased up to ß900°C or 1300°C if insulated casings or water-cooled furnaces are used in the HRSG, respectively. 43 This temperature restriction affects the amount of fuel that can be burned in the supplementary firing system, which limits the maximum CO 2 concentration that can be attained in the flue gas.…”

“…12 Further advanced configurations with exhaust gas recirculation and different options for the integration of the supplementary firing NGCC and the amine capture plant can be found elsewhere. 14,20,21 However, all these configurations come at the expense of an increase in complexity and reduced flexibility of the NGCC power plant, and further techno-economic analysis is required in order to quantify the actual advantages of these systems.…”