Oxy-combustion for gas turbine applications

Abstract

Faced with the increasing concern about the effect of greenhouse gases in global warming, Carbon Capture and Storage technologies are developed. Oxy-combustion is one of these techniques; it consists of separating the nitrogen from the air and using the O2 (diluted in CO2) as an oxidant so that the resulting flue gases are mainly composed by carbon dioxide and water vapour and the capture of CO2 can be done easily after condensing the steam. Changing the working fluid from air to O2/CO2 modifies combustion properties what might have consequences on the range of operability of the combustor. In order to design a combustor for oxy-fuel cycles in gas turbine applications, the differences between air and oxyfuel’s operational zone at low and high pressures are studied. For comparing their stability, laminar flame speed is computed for air-fuel and oxy-fuel mixtures near stoichiometric equivalence ratios (1-0.95). Diffusion effect is studied as a possible cause of the change in combustion properties when modifying the working media by computing the residence time of blowout of the same mixtures.