Numerical investigations of methane fueled oxy-fuel combustion model in a gas turbine combustor 1. Flow fields, temperature, and species distribution 2. Effect of CO_2 recirculation

摘要

Oxyfuel combustion represents one of the major options for carbon capture technologies. The effect of the amount of CO_2 recirculated and the recirculation temperature on the combustion characteristics were investigated numerically and the results were compared with the experimental work of two literature studies. The two studies have been done on the same combustion chamber. The first study investigates a gas turbine combustor for three swirling CH_4/air diffusion flames at atmospheric pressure. In our work, the most stable flame in the experimental work was taken in order to validate our code for the combustion of pure air only. The second study describes experiments on partially premixed swirl stabilized oxyfuel flames carried out on the same gas turbine combustor. The blends of O_2/CO_2 used in this study were 26% O_2 (74% CO_2), 30% O_2, 34% O_2, 38% O_2, in addition to atmospheric air that was added in this study to be our reference case. The results showed a good agreements with the experimental data in case of the combustion with air for the first study. Also in the second study for the oxy-fuel combustion, good agreements with the experimental data have been obtained. The results showed that the flame speed will be reduced when substituting N_2 by CO_2 in the oxidizer. This causes poor combustion performance and a modified distribution of temperature and species in the combustion chamber. Nearly, the oxidizer mixtures between 34% and 38% O_2 gives the same adiabatic temperature as atmospheric air.