• Korean Chemical Engineering Research
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• v.49 no.6
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• pp.688-696
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• 2011

Hydrogen is one of the few long-term sustainable clean energy carriers, emitting only water as by-products during its combustion or oxidation. The use of fossil fuels to produce hydrogen makes large amount of carbon dioxide (>7 kg $CO_{2}$/kg $H_{2}$) during the reforming processes. Hydrogen production can be environmentally benign only if the energy and the resource to make hydrogen is sustainable and renewable. Biomass is an attractive alternative to fossil fuels for carbon dioxide because of the hydrogen can be produced by conversion of the biomass and the carbon dioxide formed during hydrogen production is consumed by biomass generation process. Hydrogen production using solar energy also attracts great attention because of the potential to use abundance natural energy and water.

• Journal of Hydrogen and New Energy
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• v.30 no.6
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• pp.485-489
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• 2019

Hydrogen is known to be a clean fuel which does not generate a green house gas during the combustion. However, about 8 kg of carbon dioxide is generated during the course of producing 1 kg of hydrogen through reforming, water gas shift reaction and pressure swing adsorption in order to obtain a high purity hydrogen over 99.999% by volume. In this work, carbon dioxide generation is estimated according to four kinds of natural gas compositions supplied by Korea Gas Corporation and regarding natural gas as pure methane. For the simulation of the modeling, PRO/II with PROVISION V10.2 at AVEVA was utilized and Peng-Robinson equation of state with Twu's alpha function was selected.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1413-1417
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• 1999

Chemical poisoning of Ni/MgO catalyst was induced by hot alkali carbonate vapor in molten carbonate fuel cell (MCFC), and the poisoned (or contaminated) catalyst was characterized by TPR/TPO, FTIR, and XRD analysis. Carbonate electrolytes such as K and Li were transferred to the catalyst during DIR-MCFC operation at 650 ℃. The deposition of alkali species on the catalyst consequently led to physical blocking on catalytic active sites and structural deformation by chemical poisoning. TPR/TPO analysis indicated that K species enhanced the reducibility of NiO thin film over Ni as co-catalyst, and Li species lessened the reducibility of metallic Ni by chemical reaction with MgO. FTIR analysis of the poisoned catalyst did not exhibit the characteristic ${\vector}_1$$(D_{3h})$ peaks (1055 $cm^{-1},\;1085\;cm{-1})$ for pure crystalline carbonates, instead a new peak (1120 $cm^{-1})$ was observed proportionally with deformed alkali carbonates. From XRD analysis, the oxidation of metallic Ni into $Ni_xMg_{1-x}O$ was confirmed by the peak shift of MgO with shrinking of Ni particles. Conclusively, hot alkali species induced both chemical poisoning and physical deposition on Ni/MgO catalyst in DIR-MCFC at 650 ℃.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.6_3
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• pp.1247-1260
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• 2022

The steel industry accounts for about 5% of the total annual global energy consumption and more than 6% of the total anthropogenic carbon dioxide emissions. Therefore, there is a need to increase energy efficiency and reduce greenhouse gas emissions in these industries. The utilization of coke oven gas, a byproduct of the coke plant, is one of the main ways to achieve this goal. Coke oven gas used as a fuel in many steelmaking process is a hydrogen-rich gas with high energy potential, but it is commonly used as a heat source and is even released directly into the air after combustion reactions. In order to solve such resource waste and energy inefficiency, several alternatives have recently been proposed, such as separating and refining hydrogen directly from coke oven gas or converting it to syngas. Therefore, in this study, recent research trends on the separation and purification of hydrogen from coke oven gas and the production of syngas were introduced.

• Journal of Hydrogen and New Energy
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• v.33 no.6
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• pp.607-615
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• 2022

In this study, economic analysis program was developed for economic evaluation of hydrogen production, storage/delivery, and utilization technologies as well as overseas import of hydrogen. Economic analysis program can be used for the estimation of the levelized cost of hydrogen for hydrogen supply chain technologies. This program include five hydrogen production technology on steam methane reforming and water electrolysis, two hydrogen storage technologies (high compressed gas and liquid hydrogen storage), three hydrogen delivery technologies (compressed gas delivery using tube trailer, liquid hydrogen, and pipeline transportation) and six hydrogen utilization technologies on hydrogen refueling station and stationary fuel cell system. In the case of overseas import hydrogen, it was considered to be imported from five countries (Austraila, Chile, India, Morocco, and UAE), and the transportation methods was based on liquid hydrogen, ammonia, and liquid organic hydrogen carrier. Economic analysis program that was developed in this study can be expected to utilize for planning a detailed implementation methods and hydrogen supply strategies for the hydrogen economy road map of government.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.3
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• pp.343-350
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• 2012

A planar solid oxide fuel cell (PSOFC) is studied in its application in a high-temperature stationary power plant. Even though PSOFCs with external reformers are designed for application from the distributed power source to the central power plant, such PSOFCs may sacrifice more system efficiency than internally reformed SOFCs. In this study, modeling of the PSOFC with an external reformer was developed to analyze the feasibility of thermal energy utilization for the external reformer. The PSOFC system model includes the stack, reformer, burner, heat exchanger, blower, pump, PID controller, 3-way valve, reactor, mixer, and steam separator. The model was developed under the Matlab/Simulink environment with Thermolib$^{(R)}$ modules. The model was used to study the system performance according to its configuration. Three configurations of the SOFC system were selected for the comparison of the system performance. The system configuration considered the cathode recirculation, thermal sources for the external reformer, heat-up of operating gases, and condensate anode off-gas for the enhancement of the fuel concentration. The simulation results show that the magnitude of the electric efficiency of the PSOFC system for Case 2 is 12.13% higher than that for Case 1 (reference case), and the thermal efficiency of the PSOFC system for Case 3 is 76.12%, which is the highest of all the cases investigated.

• Korean Chemical Engineering Research
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• v.45 no.6
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• pp.656-662
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• 2007

Fuel reformer using plasma and shift reactor for CO oxidation were designed and manufactured as $H_2$ supply device to operate a polymer electrolyte membrane fuel cell (PEMFC). $H_2$ selectivity was increased by non-thermal plasma reformer using GlidArc discharge with Ni catalyst simultaneously. Shift reactor was consisted of steam generator, low temperature shifter, high temperature shifter and preferential oxidation reactor. Parametric screening studies of fuel reformer were conducted, in which there were the variations of the catalyst temperature, gas component ratio, total gas ratio and input power. and parametric screening studies of shift reactor were conducted, in which there were the variations of the air flow rate, stema flow rate and temperature. When the $O_2/C$ ratio was 0.64, total gas flow rate was 14.2 l/min, catalytic reactor temperature was $672^{\circ}C$ and input power 1.1 kJ/L, the production of $H_2$ was maximized 41.1%. And $CH_4$ conversion rate, $H_2$ yield and reformer energy density were 88.7%, 54% and 35.2% respectively. When the $O_2/C$ ratio was 0.3 in the PrOx reactor, steam flow ratio was 2.8 in the HTS, and temperature were 475, 314, 260, $235^{\circ}C$ in the HTS, LTS, PrOx, the conversion of CO was optimized conditions of shift reactor using simulated reformate gas. Preheat time of the reactor using plasma was 30 min, component of reformed gas from shift reactor were $H_2$ 38%, CO<10 ppm, $N_2$ 36%, $CO_2$ 21% and $CH_4$ 4%.

• Korean Chemical Engineering Research
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• v.56 no.4
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• pp.496-523
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• 2018

The objective of this study is to evaluate the economic feasibility of two fast pyrolysis and biooil upgrading (FPBU) plants including feed drying, fast pyrolysis by fluidized-bed, biooil recovery, hydro-processing for biooil upgrading, electricity generation, and wastewater treatment. The two FPBU plants are Case 1 of an FPBU plant with steam methane reforming (SMR) for $H_2$ generation (FPBU-HG, 20% yield), and Case 2 of an FPBU with external $H_2$ supply (FPBUEH, 25% yield). The process flow diagrams (PFDs) for the two plants were constructed, and the mass and energy balances were calculated, using a commercial process simulator (ASPEN Plus). A four-level economic potential approach (4-level EP) was used for techno-economic analysis (TEA) under the assumption of sawdust 100 t//d containing 40% water, 30% equity, capital expenditure equal to the equity, $H_2$ price of $1050/ton, and hydrocarbon yield from dried sawdust equal to 20 and 25 % for Case 1 and 2, respectively. TCI (total capital investment), TPC (total production cost), ASR (annual sales revenue), and MFSP (minimum fuel selling price) of Case 1 were $22.2 million, $3.98 million/yr, $4.64 million/yr, and $1.56/l, respectively. Those of Case 2 were $16.1 million, $5.20 million/yr, $5.55 million/yr, and $1.18/l, respectively. Both ROI (return on investment) and PBP (payback period) of Case 1(FPBU-HG) and Case 2(FPBU-EH) were the almost same. If the plant capacity increases into 1,500 t/d for Case 1 and Case 2, ROI would be improved into 15%/yr.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.40 no.3
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• pp.173-179
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• 2016

This is a numerical study on the curved channel type of hydrogen reformer using the commercial code of fluid dynamics. We numerically compared the numerical model in a previous study model and the modelling of a tube type curved channel. In the result of numerical analysis on 4 types of curved channel reformers, the methanol conversion efficiency of type 1~4 were 45.0%, 45.3%, 45.6%, 45.6% respectively, and there was hardly any difference by ${\pm}0.6%$. In light of flow characteristics, the rectangle type tube and the type 2 with $45^{\circ}$ turn showed most uniform flow characteristics and concentration distribution of methanol, and the circular type tube and the type 3 with $90^{\circ}$ turn had most un-uniform flow characteristics and concentration distribution of methanol. We concluded that the design for curved channel reformer has to have rectangle type tube with curve of almost $45^{\circ}$ as in the type of curved pipe with $45^{\circ}$ turn.

• Applied Chemistry for Engineering
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• v.19 no.2
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• pp.157-160
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• 2008

The generation of high-purity hydrogen from hydrocarbon fuels is essential for efficient operation of fuel cell. In general, most feasible strategies to generate hydrogen from hydrocarbon fuels consist of a reforming step to generate a mixture of $H_2$, CO, $CO_2$ and $H_2O$ (steam) followed by water gas shift (WGS) and CO clean-up steps. The WGS reaction that shifts CO to $CO_2$ and simultaneously produces another mole of $H_2$ was carried out in a two-stage catalytic conversion process involving a high temperature shift (HTS) and a low temperature shift (LTS). In a typical operation, gas emerges from the reformer is taken through a high temperature shift catalyst to reduce the CO concentration to about 3~5%. The HTS reactor was designed and tested in this study to produce hydrogen-rich gas with CO to a range of 2~4%. The iron based catalysts (G-3C) was used for the HTS to convert the most of CO in the effluent from the partial oxidation (POX) to $H_2$ and $CO_2$ at a relatively high rate. Parametric screening studies were carried out for variations of the following variables: reaction temperature, steam flow rate, components ratio ($H_2/CO$), and reforming gas flow rate.