TY - JOUR
T1 - The effects of CO2/CH4 ratio on soot formation for autothermal reforming of methane at elevated pressure
AU - Liu, Peng
AU - Guo, Junjun
AU - Im, Hong G.
AU - Roberts, William L.
N1 - Funding Information:
This work was supported by Air Products through its projects of RGC/3/4490-01-01 and RGC/3/4143-01-01. The computational resources were provided by the KAUST Supercomputing Laboratory (KSL). PL and WR gratefully acknowledge the funding from KAUST CRG project under project number URF/1/4688-01-01.
Publisher Copyright:
© 2022
PY - 2022
Y1 - 2022
N2 - Autothermal reforming of methane (ATR) technique is a promising technology for H2 production. Soot formed in the combustion region of ATR may deactivate the downstream catalyst used to enhance the reforming reactions. In this work, the effects of CO2/CH4 ratio on soot production and main gas-phase components involved in reforming reactions were investigated by experiment and numerical simulations in laminar inverse coflow diffusion flames, at conditions close to ATR. The CO2/CH4 ratio ranges from 0.27 to 4.90, and the pressure ranges from 1 atm to 10 atm. The oxidant consists 70% O2 and 30% N2 to mimic the oxy-combustion in the ATR process. The soot, polycyclic aromatic hydrocarbon (PAHs), OH* distribution, and flame structure were measured using planar laser-induced incandesce, planar laser-induced fluorescence, OH* luminescence, and flame luminescence, respectively. High fidelity simulations with a reduced gas-phase kinetic mechanism and soot aerosol models were also undertaken to supplement the findings. The results show that soot formation is suppressed by a higher CO2/CH4 ratio, while the level of soot reduction is attenuated as the pressure increases. The peak soot volume fraction increases with the flame height, and then levels off. PAHs concentration monotonically increases with flame height. The spatial distributions of PAH and soot along flame height were not well captured by numerical simulations, and the used physical based soot inception model is expected to account for the discrepancy. The peak soot volume fraction correlates with CO2/CH4 ratio by an exponentially decaying function, with the exponent decreasing with increasing pressure. A similar trend of PAHs concentration along with CO2/CH4 ratio was also observed. Non-sooting flame is achievable at elevated pressure if the CO2/CH4 ratio is higher than 4.0, at the expense of lowering the syngas yield in the combustion region. The simulations also predicted that the flame temperature and concentration of H2 and CO decrease with CO2/CH4 ratio.
AB - Autothermal reforming of methane (ATR) technique is a promising technology for H2 production. Soot formed in the combustion region of ATR may deactivate the downstream catalyst used to enhance the reforming reactions. In this work, the effects of CO2/CH4 ratio on soot production and main gas-phase components involved in reforming reactions were investigated by experiment and numerical simulations in laminar inverse coflow diffusion flames, at conditions close to ATR. The CO2/CH4 ratio ranges from 0.27 to 4.90, and the pressure ranges from 1 atm to 10 atm. The oxidant consists 70% O2 and 30% N2 to mimic the oxy-combustion in the ATR process. The soot, polycyclic aromatic hydrocarbon (PAHs), OH* distribution, and flame structure were measured using planar laser-induced incandesce, planar laser-induced fluorescence, OH* luminescence, and flame luminescence, respectively. High fidelity simulations with a reduced gas-phase kinetic mechanism and soot aerosol models were also undertaken to supplement the findings. The results show that soot formation is suppressed by a higher CO2/CH4 ratio, while the level of soot reduction is attenuated as the pressure increases. The peak soot volume fraction increases with the flame height, and then levels off. PAHs concentration monotonically increases with flame height. The spatial distributions of PAH and soot along flame height were not well captured by numerical simulations, and the used physical based soot inception model is expected to account for the discrepancy. The peak soot volume fraction correlates with CO2/CH4 ratio by an exponentially decaying function, with the exponent decreasing with increasing pressure. A similar trend of PAHs concentration along with CO2/CH4 ratio was also observed. Non-sooting flame is achievable at elevated pressure if the CO2/CH4 ratio is higher than 4.0, at the expense of lowering the syngas yield in the combustion region. The simulations also predicted that the flame temperature and concentration of H2 and CO decrease with CO2/CH4 ratio.
KW - Autothermal reforming
KW - CO
KW - Inverse coflow diffusion flame
KW - Oxy-combustion
KW - Soot
UR - http://www.scopus.com/inward/record.url?scp=85139034521&partnerID=8YFLogxK
U2 - 10.1016/j.combustflame.2022.112379
DO - 10.1016/j.combustflame.2022.112379
M3 - Article
AN - SCOPUS:85139034521
SN - 0010-2180
VL - 258
JO - Combustion and Flame
JF - Combustion and Flame
M1 - 112379
ER -