Natural gas oxy-combustion with flue gas recycling for CO2 capture
Résumé
The purpose of this work is to study and compare combustion of natural gas in air and
oxy-combustion with flue gas recycling in order to optimize this technology. This paper
presents several experiments of natural gas combustion using air (or enriched air) or a
mixture of pure oxygen mixed to recycled flue gas (O2/CO2/H2O) as oxidizer. The trials
were conducted on a 300 kWth pilot-scale facility, composed of a burner, a combustion
chamber, a flue gas cooler and a flue gas recycle fan. Flue gas composition, O2
concentration in the feeding gas and the flame temperature were monitored.
This study aims at analyzing the influence of the nature of the oxidizer, O2
concentration in the feed gas, oxygen excess and recycling ratio on flame temperature
profile, heat transfer, flue gas composition and NOx emissions.
The results obtained showed that the flame temperature with 21% O2 concentration in
the feed gas is lower for oxy-combustion than combustion in air. However, the
recycling ratio can be adjusted to control the flame temperature and an O2 concentration
of 24% in the feed gas is necessary to maintain a temperature profile similar to that
observed for combustion in air. It has been observed also that oxy-combustion with flue
gas recycling improves the heat transfer. Finally, the results showed also that the NOx
emissions are highly reduced because of the absence of N2 in the feed gas.