In an energetic world of fossil fuel, there is a need to reduce the CO2 emission released to the atmosphere. CO2 Capture and Sequestration (CCS) is one of the solutions.

To optimize the CO2 capture cost, thermodynamic cycles of power plants have to be modified, and resulting new designs inevitably lead to new combustion modes [1][2][3]. CO2 capture of post combustion gases can be performed using membrane processes, but its efficiency is interesting only if the CO2 concentration in the combustion process exhaust gases is higher than 30% [4]. Unfortunately, in classical combustion processes (e.g. gas turbine), diluted Exhaust Gases (EG) contain no more than 5 % of CO2 because combustion products are strongly diluted in air. Our objective consists in increasing the EG CO2 concentration, by using both Oxygen-Enriched Air (OEA) combustion and exhaust gas recirculation (EGR). Our approach is based on numerical simulations and on experimental work. First, operating parameters which minimize the CO2 capture cost are calculated and compared with the reference capture cost [5] (achieved by amine absorption of CO2). In parallel, experiments and additional calculations are performed in order to check the quality and the operability of such combustion mode.

This paper is organized as follows: the first part presents the optimization of a new thermodynamic GTCC cycle, using OEA and EGR to increase EG CO2 concentration and capturing it in post-combustion with membrane separator. The effects of pressure and membrane selectivity will be studied in terms of CO2 capture cost, avoided CO2, implemented membrane surface, EGR rate and OEA quality.

The second part is dedicated to the experimental and calculation [6] studies of combustion met in this type of configuration. A premixed swirl flame is fed first with Air, CH4 and CO2, then with OEA, CH4 and EGR. To neglect the thermal aspect of NOx production, measurements are performed at constant adiabatic flame temperature. The flame structure, combustion instability and pollutant emissions are presented as a function of the EGR rate dilution.

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