Innovative Design & Performance Assessment of a Novel Modular Reactor for One-Step Liquid Fuel Production from Stranded Natural Gas
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Date
2024-03
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Abstract
The crude extraction process faces a challenge in tackling the associated natural gas that is dissolved in the crude oil or prevails in the free gas caps of oil reservoirs. Considering the risks and costs involved in natural gas transportation, the quantity of associated gas is very small to substantiate the construction of a pipeline network. Although this associated natural gas is the by-product of the oil extraction process, the absence of a viable solution for utilization makes it ‘stranded natural gas (SNG).’ Approximately 15 tons/day of SNG is flared from one oil well, contributing to greenhouse gases. The uneconomical nature of pipeline installation to transport SNG and the necessity to find a robust solution to tackle SNG opens an avenue for developing modular technologies that can convert SNG to value-added products while reducing CO2 emissions. Liquid fuels (LF) are high-density energy carriers that are easy to transport and can support the existing infrastructure for energy consumption. 15 tons/day of SNG that is flared has the potential to produce ~2.5 tons/day of LF and generate ~115 kW of electricity simultaneously. This work proposes a single reactor modular unit that converts SNG to value-added LF. The novel reactor configuration consists of a multi-tubular packed bed setup divided into three intermediate sections: a mixed reforming section, a section for heat exchange, and a Fischer-Tropsch (FT) section. Mixed reforming of SNG uses CO2 and steam to produce high-quality syngas (H2:CO = 1.7), which in turn can be used to produce liquid fuels in the FT section of the reactor. The heat exchange section assists in increasing the efficiency of the process by facilitating heat integration within the process streams. This process provides inherent CO2 utilization and converts pressurized SNG to easy-to-transport liquid fuels that can be processed to manufacture motor spirit, diesel, jet engine fuels, and feedstocks for the petrochemical industry. System-level thermodynamic evaluation was conducted using ASPEN Plus software for the production of 2.5 tons/day of liquid fuel by taking into consideration multiple plausible cases of reactor configuration and heat integration. Detailed economic calculations performed based on the tubular reactor design for all configurations indicate that the production of liquid fuels using SNG can prove to be a profitable venture. The design of the multi-tubular reactor and the economics associated with it are simultaneously optimized using the Bayesian optimization technique to propose a portable, modular reactor requiring a minimum number of units to process the SNG from an oil well. The robustness of the best-case scenario is then validated for fluctuating SNG compositions, flow rates, and temperatures. This work establishes the design feasibility of a novel, economically viable, modular technology for upgrading SNG to value-added liquid fuels while reducing greenhouse gas emissions.
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Poster Division: Engineering: 1st Place (The Ohio State University Edward F. Hayes Advanced Research Forum)