Analysis of methane, propane, and syngas oxy‐flames in a fuel‐flex gas turbine combustor for carbon capture

Abstract

Premixed oxy-combustion flames of methane, syngas (CH 4 :CO:H 2 with the molar ratio of 2:1:1), and propane in CO 2 -diluted environment (for carbon capture) are examined in a swirl-stabilized combustor using large eddy simulations (LES) in three-dimensional (3-D) domain. The flame and emission characteristics are examined for the different fuels over a range of equivalence ratios (Φ: 0.34, 0.39, and 0.42), at 60% oxygen fraction (OF), and 2.5 m/s bulk inlet velocity under atmospheric conditions. The results indicate increments in several characteristic parameters that are of special importance for gas turbine combustion applications, including adiabatic flame temperature (T ad ), laminar flame speed (LFS), power density (PD), product formation rate (PFR), Damköhler number (Da), and CO emission, with the increase of Φ whatever the type of fuel. Alternatively, flame thickness (δ) decreases with the increase in Φ for the three fuels. Characteristic "V" shape with almost identical outer recirculation zone (ORZ) is also observed for the three fuels. Among the studied fuels, oxy-methane flames demonstrate highest flame thicknesses, least uniform temperature distribution (highest pattern factor) at combustor outlet, and lowest CO emission level. Oxy-syngas flames show more uniform temperature distribution (lowest pattern factor) at combustor outlet and highest CO emission as compared with the oxy-methane and oxy-propane flames. The oxy-propane flames have higher values of T ad , LFS, PD, PFR, Da, and thermal power (TP) along with lowest flame thickness compared with methane and syngas counterparts. Highlights• Increasing equivalence ratio improves the flame characteristics but increases CO emission.• Fuel type has insignificant effects on shape/size of the outer recirculation zone (ORZ).• Oxy-methane flames showed highest flame thicknesses and pattern factor and lowest CO.

Analysis of Highly CO2-Diluted Oxy-propane Flames Stabilized over a Multihole Burner of a Model Gas Turbine Combustor

“…The Damköhler number ( Da ) refers to the ratio of reaction rate to diffusion rate (in other words, ratio between flow time scale and chemical time scale) and can be evaluated from eq . , The terms l t and u ′ correspond to the integral length scale and root mean square (RMS) of velocity fluctuation. D a = true l t u ′ r m s true δ S L …”

“…The Damkoḧler number (Da) refers to the ratio of reaction rate to diffusion rate (in other words, ratio between flow time scale and chemical time scale 32 ) and can be evaluated from eq 14. 21,33 The terms l t and u′ correspond to the integral length scale and root mean square (RMS) of velocity fluctuation. The pattern factor as provided in eq 15 corresponds to the temperature uniformity at the combustor outlet, where T maximum and T average are the maximum and average temperatures at the outlet of the combustor, respectively.…”

“…Propane can also be present in liquified natural gas (LNG), used in different fuel blends, and can be an alternative to ‘Jet A’ fuel for turboshaft engines . Also from a preliminary study done by the authors, it is observed that oxy-propane flames are capable of providing slightly higher power density that methane and syngas counterparts at identical bulk inlet velocity . Thus, understanding propane combustion is necessary for its possible application.…”

“… 20 Also from a preliminary study done by the authors, it is observed that oxy-propane flames are capable of providing slightly higher power density that methane and syngas counterparts at identical bulk inlet velocity. 21 Thus, understanding propane combustion is necessary for its possible application. The study of oxy-propane flames in this specific burner has not been performed so far.…”