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Thermodynamic analysis of a proton conducting SOFC integrated system fuelled by different renewable fuels
(2021-03-19)
Saebea, Dang
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Arpornwichanop, Amornchai
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Patcharavorachot, Yaneeporn
This work proposes a power generation system consisting of steam reformer and SOFC–H+ fuelled by different types of fuel, i.e., ethanol, glycerol and biogas. The performance analysis of integrated system is performed based on thermodynamic calculation through Aspen Plus simulator. The total of the Gibbs free energy minimization is used to determine product composition at equilibrium. The electrochemical model not only considers all voltage losses but also includes the effect of current leakage as a result from the electrolyte used. Considering the operating condition of steam reformer, it is found that the gas product contains the highest amount of hydrogen without the carbon formation when reformer is operated at 973 K with steam to carbon ratio of 1. In addition, the simulation results show that the SOFC–H+ operated at 973 K and 1 A/cm2 can provide a suitable compromise between system performances and exhaust gas composition. The use of glycerol reformate has the highest cell and system efficiencies and fuel utilization compared to the others. In addition, the integrated system fuelled by glycerol can release low CO amount whereas there is more heat provided to the surrounding. Therefore, it can be concluded that glycerol is suitable renewable fuel for SOFC–H+ integrated system.
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Optimization of hydrogen production from three reforming approaches of glycerol via using supercritical water with in situ CO2 separation
(2019-01-22)
Patcharavorachot, Yaneeporn
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Chatrattanawet, Narissara
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Arpornwichanop, Amornchai
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Assabumrungrat, Suttichai
A pathway for hydrogen production from supercritical water reforming of glycerol integrated with in situ CO<inf>2</inf> removal was proposed and analyzed. The thermodynamic analysis carried out by the minimizing Gibbs free energy method of three glycerol reforming processes for hydrogen production was investigated in terms of equilibrium compositions and energy consumption using AspenPlus™ simulator. The effect of operating condition, i.e., temperature, pressure, steam to glycerol (S/G) ratio, calcium oxide to glycerol (CaO/G) ratio, air to glycerol (A/G) ratio, and nickel oxide to glycerol (NiO/G) ratio on the hydrogen production was investigated. The optimum operating conditions under maximum H<inf>2</inf> production were predicted at 450 °C (only steam reforming), 400 °C (for autothermal reforming and chemical looping reforming), 240 atm, S/G ratio of 40, CaO/G ratio of 2.5, A/G ratio of 1 (for autothermal reforming), and NiO/G ratio of 1 (for chemical looping reforming). Compared to three reforming processes, the steam reforming obtained the highest hydrogen purity and yield. Moreover, it was found that only autothermal reforming and chemical looping reforming were possible to operate under the thermal self-sufficient condition, which the hydrogen purity of chemical looping reforming (92.14%) was higher than that of autothermal reforming (52.98%). Under both the maximum H<inf>2</inf> production and thermal self-sufficient conditions, the amount of CO was found below 50 ppm for all reforming processes.
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Performance comparison of solid oxide steam electrolysis cells with/without the addition of methane
(2016-07-15)
Patcharavorachot, Yaneeporn
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Thongdee, Sirapa
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Saebea, Dang
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Authayanun, Suthida
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Arpornwichanop, Amornchai
Hydrogen is considered a clean energy carrier for the future. At present, the production of hydrogen via a solid oxide electrolysis cell is of interest because water is the only reactant used; however, hydrogen production through electrolysis technology is still costly due to high electrical energy consumption. To reduce this energy demand, an addition of methane to the anode side of the solid oxide electrolysis cell, where it behaves like the anode side of the solid oxide fuel cell and generates heat and electricity to accomplish the electrolysis process, is one interesting method. In this study, modeling of the solid oxide fuel-assisted electrolysis cell is performed based on an electrochemical model to analyze the performance of the electrolyzer with/without the addition of methane in terms of the power input and the energy efficiency. In addition, the effect on the electrolyzer cell by key operating parameters, such as current density, steam fraction, steam-to-carbon ratio, temperature, pressure, steam utilization and fuel utilization, is presented. The simulation analysis shows that the performance of the solid oxide fuel-assisted electrolysis cell is higher than that of conventional solid oxide electrolysis cell, as it requires a lower power input. Furthermore, it is possible to run the solid oxide fuel-assisted electrolysis cell without an external electrical energy input.
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Catalytic reforming of glycerol in supercritical water with nickel-based catalysts
(2014-09-12)
Pairojpiriyakul, Thirasak
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Croiset, Eric
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Kiatkittipong, Kunlanan
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Kiatkittipong, Worapon
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Arpornwichanop, Amornchai
The catalytic performance of nickel catalysts supported on La <inf>2</inf>O<inf>3</inf>, α-Al<inf>2</inf>O<inf>3</inf>, γ-Al <inf>2</inf>O<inf>3</inf>, ZrO<inf>2</inf>, and YSZ for supercritical water reforming of glycerol was investigated. Experiments were conducted in a tubular reactor made of Inconel-625 with the temperature range of 723-848 K under a pressure of 25 MPa. Carbon formation causing operation failure was observed for α-Al<inf>2</inf>O<inf>3</inf>, γ-Al<inf>2</inf>O<inf>3</inf> and ZrO<inf>2</inf> at temperatures higher than 748, 798 and 823 K, respectively. Ni/La<inf>2</inf>O<inf>3</inf> exhibited the highest H<inf>2</inf> yield where almost complete conversion was obtained at 798 K. Moderate space velocities (WHSV = 6.45 h-1) and glycerol feed concentration (5wt.%) favor high hydrogen selectivity and yield. Methanation is favored at a low WHSV or high glycerol feed concentration, resulting in a lower H<inf>2</inf> yield. Increasing Ni loading on the Ni/La<inf>2</inf>O<inf>3</inf> catalyst strongly promoted the reforming, water-gas shift, and methanation reactions, which contributed significantly to the product species distribution. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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Integration of ethanol processor and CO2 absorption to produce hydrogen for fuel cell
(2014-01-01)
Patcharavorachot, Yaneeporn
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Sangduan, Kidakarn
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Ponpesh, Pimporn
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Assabumrungrat, Suttichai
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Arpornwichanop, Amornchai
Ethanol is considered to be a promising candidate for hydrogen source. Hydrogen-rich gas with less impurity level of carbon monoxide and carbon dioxide is required for fuel cell applications. In a conventional ethanol processor, CO can be removed by water gas-shift reactors, followed by a preferential oxidation unit. Since a high content of CO<inf>2</inf> may degrade the efficiency of fuel cell systems, the removal of CO<inf>2</inf> should be included in the ethanol processor to separate CO<inf>2</inf> from the synthesis gas. In this study, the thermodynamic analysis of hydrogen production from the integration of ethanol reforming process and CO<inf>2</inf> absorption unit is performed. The purity of H2, efficiency of CO<inf>2</inf> removal and heat consumption are key factors to be analyzed with regard to different key parameters. The result indicates that the H2 purity of 97 mol.% can be reached when the CO<inf>2</inf> absorption unit is included in the ethanol steam reforming. In addition, it is found that the CO<inf>2</inf> removal can be improved with increases of amine concentration, number of absorber and stripper stages, whereas increase of inlet gas temperature show the opposite trend. However, high energy demand is unavoidable when a number of absorber and stripper stages increase.
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Thermodynamic analysis of hydrogen production from the adsorption-enhanced steam reforming of biogas
(2014-01-01)
Saebea, Dang
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Authayanun, Suthida
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Patcharavorachot, Yaneeporn
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Arpornwichanop, Amornchai
Biogas is considered a potential, renewable fuel to be used as a hydrogen source. At present, a steam reforming is widely used process in hydrogen production, but it needs to be operated at high temperature to achieve high hydrogen yield. Because biogas consists of mostly CO<inf>2</inf>, the hydrogen purification of a reformate gas obtained is another important issue, especially for fuel cell applications. In this study, an enhanced-adsorption steam reforming process in which steam reforming reaction and CO<inf>2</inf> adsorption are occurred in a single unit is investigated. A thermodynamic analysis is performed to study effects of important operating parameters on hydrogen yield and product distribution. It is found that a biogas processor should be operated at high temperatures and inlet steam-T o-methane ratio. The content of CO in the reformate gas increases with increased operating temperature. The steam reforming of biogas coupled with a CO<inf>2</inf> adsorption gives a higher hydrogen product with considerable low CO content, compared to the conventional steam reforming of biogas.
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Hydrogen production from catalytic supercritical water reforming of glycerol with cobalt-based catalysts
(2013-04-15)
Pairojpiriyakul, Thirasak
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Croiset, Eric
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Kiatkittipong, Worapon
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Kiatkittipong, Kunlanan
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Arpornwichanop, Amornchai
Glycerol reforming under catalytic supercritical water at temperatures in the range of 723-848 K using Co catalyst deposited on various supports including ZrO<inf>2</inf>, yttria-stabilized zirconia (YSZ), La<inf>2</inf>O<inf>3</inf>, γ-Al<inf>2</inf>O<inf>3</inf>, and α-Al<inf>2</inf>O<inf>3</inf> was investigated. An increase in operating temperature promoted the continued increase in glycerol conversion; however, carbon formation causing system operation failure was observed for γ-Al<inf>2</inf>O<inf>3</inf> and α-Al<inf>2</inf>O<inf>3</inf> at high operating temperatures (i.e. 748-798 K). Co supported on YSZ provided the most efficient performance for hydrogen production. 10 wt.% Co loading on YSZ support was an optimum amount to enhance the reaction. The increase in glycerol conversion and reduction of the amount of liquid products were observed for lower weight hourly space velocity (WHSV), higher operating temperature or higher cobalt loading. On Co/YSZ catalyst, glycerol conversion of 0.94 and hydrogen yield of 3.72 was obtained with WHSV of 6.45 h-1at 773 K. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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Use of different renewable fuels in a steam reformer integrated into a solid oxide fuel cell: Theoretical analysis and performance comparison
(2013-01-01)
Saebea, Dang
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Authayanun, Suthida
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Patcharavorachot, Yaneeporn
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Paengjuntuek, Woranee
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Arpornwichanop, Amornchai
Hydrogen production from renewable energy resources has received significant attention with advances in fuel cell technology. The fuel type and operational reforming conditions directly affect fuel cell electricity generation. This study analyzes the theoretical performance of a solid oxide fuel cell (SOFC) integrated with a steam reforming process using three different renewable fuels: ethanol, glycerol and biogas. The effects of key steam reformer operating parameters on the hydrogen production for SOFCs are investigated. The performances of SOFC systems run on different fuels are compared in terms of electrical and thermal efficiencies. It is found that the biogas-fueled SOFC system requires the most energy, whereas the ethanol-fueled SOFC system achieves the highest electrical and thermal efficiencies. © 2012 Elsevier Ltd.

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