Journal of Applied and Physical Sciences
Details
Journal ISSN: 2414-3103
Article DOI: https://doi.org/10.20474/japs-3.3.1
Received: 18 January 2017
Accepted: 22 March 2017
Published: 16 October 2017
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  • A novel forced unsteady state operation method in methanation of synthesis gas: Analysis, modelling, and simulation

Ivan Ruben Darmawan, Ivan, Henry Sutjiono

Article first published online: 2017

Abstract

Recent fuels and chemicals production are mainly generated from crude oil and Natural Gas (NG) which are non-renewable sources and could be detrimental to the environment. Biomass is an ecofriendly and renewable energy source with a big potential to replace crude oil and NG in the future. However, enhancing the low energy density of biomass has been a constant challenge. Conversion of biomass into Synthetic Natural Gas (SNG) via gasification and methanation could be a favorable route to increase the potential use of biomass. The advantages of SNG are the high energy content and efficient end-use technologies, further supported by well-established gas distribution infrastructures. First, biomass is gasified into synthesis gas before entering the methanation process. Methanation then converts synthesis gas into methane and it is usually operated in a catalytic fixed-bed reactor under steady-state condition. In this study, Forced Unsteady-State Operation (FUSO) was simulated by modulating flow rate of the feed gas as a novel operation method to increase the conversion of synthesis gas to methane. FUSO was held after the system had reached its steady-state condition. The feed in this process was a mixture of H2, CO, and Ar with the mole fraction of 50%, 10%, and 40%, respectively. The average feed volumetric flow rate was 0.3 lN/min and the operating conditions were 553 K with a total pressure of up to 2 barabs. The aim of this study was to investigate the effect of FUSO with various flow rate modulation patterns, amplitudes, and switching times on the conversion of synthesis gas. Modelling and simulation for both steady-state and unsteadystate conditions were developed using the FlexPDE simulation software assuming an isothermal fixed-bed reactor on Ni-based catalyst. The results were compared with bench-scale experimental data to validate the results. The simulation results compare sufficiently with the bench-scale experimental data to be validated. The simulation results showed that FUSO operation improves synthesis gas to methane conversion considerably. The highest conversion achieved was 84.79% under step pattern flow rate modulation with the amplitude of 0.6 lN/min and switching time of 3s, while the conventional steady-state operation only reached 72.99%. This study shows that FUSO can potentially be applied to synthesis gas methanation to increase conversion.