posted on 2023-12-11, 19:38authored byZeinab Ataya, Mohamed Challiwala, Gasim Ibrahim, Hanif A. Choudhury, Mahmoud M. El-Halwagi, Nimir O. Elbashir
The gas-to-liquid
(GTL) process is a promising technology for converting
natural gas into synthetic fuels and chemicals. However, its high
carbon dioxide (CO2) emissions present significant challenges.
Methane reforming contributes up to 60% of GTL’s CO2 emissions, necessitating decarbonization. Dry reforming of methane
(DRM) shows potential for CO2 conversion. Still, it faces
challenges such as high energy requirements, catalyst deactivation,
and an incompatible hydrogen-to-carbon monoxide (H2/CO)
ratio for GTL processing, requiring extensive research. A previous
study proposed a two-reactor system known as CARGEN that co-produces
solid carbon (in the form of multiwalled carbon nanotubes [MWCNTs])
and syngas, reducing CO2 emissions by 40% compared to the
benchmark autothermal reforming (ATR) process through life cycle assessment
(LCA) studies. This paper presents a comprehensive simulation of the
advanced DRM process used to retrofit an existing ATR-based GTL plantinitially,
a 50,000 bbl./day ATR-based GTL plant is simulated. The advanced reformer
process replaces ATR through retrofitting. Comparative analysis shows
a remarkable 73% reduction in net CO2 emissions and the
potential coproduction of 243 kg of MWCNTs per barrel of syncrude,
equivalent to 12,150 tons/day of MWCNTs. However, the advanced reformer-based
GTL plant requires 61% more natural gas feedstock while utilizing
79% less oxygen than the ATR-based plant. Furthermore, a separate
techno-economic analysis examines the advanced reformer-based GTL
plant based on a calculation for 13,100 tons/day of CO2 feedstock to co-produce 3,277 tons/day of MWCNTs and 50,000 barrels/day
of syncrude. This analysis, considering a 25% tax rate, 25-year plant
life, and zero salvage value, demonstrates an attractive 10-year payback
period at selling prices of 80 USD/bbl. for syncrude and 10 USD/kg
for MWCNTs. These results provide a process system-level perspective,
showcasing the advanced reformer-based GTL plant (CARGEN Process)
as an effective solution for low-carbon GTL production.