• Title, Summary, Keyword: Reformer

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Effect of Boundary Temperature Distributions on the Outlet Gas Composition of the Cylindrical Steam Reformer (원통형 수증기 개질기의 경계 온도 분포에 따른 개질 가스 조성 변화)

  • Kim, Seok;Han, Hun-Sik;Kim, Seo-Young;Hyun, Jae-Min
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.23 no.6
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    • pp.383-391
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    • 2011
  • Numerical simulations have been conducted for the cylindrical steam reformer having various boundary temperature distributions. $CH_4$, $H_2O$, CO, $H_2$ and $CO_2$ are often generated or destroyed by the reactions, namely the Steam Reofrming(SR) reaction, the Water-Gas Shift (WGS) reaction and the Direct Steam Reforming(DSR) reaction. The SR and the DSR reactions are endothermic reactions, and the WGS reaction is an exothermic reaction. The rate of reactions can be slightly controlled by artificially given boundary temperature distributions. Therefore, the component ratio of the gases at the outlet are different for various boundary temperature distributions, namely the constant, cubic and linear distributions. Among these distributions, the linear temperature distribution is outstanding for efficient hydrogen production of the steam reformer.

Theoretical Analysis and Study of Design of Autothermal Reformer for Use in Fuel Cell (연료전지용 열분해 개질기의 이론해석 및 설계연구)

  • Kang, Il-Hwan;Kim, Hyung-Man;Choi, Kap-Seung;Wang, Hak-Min
    • 한국연소학회:학술대회논문집
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    • pp.58-63
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    • 2005
  • As fuel cells approach commercialization, hydrogen production becomes a critical step in the overall energy conversion pathway. Reforming is a process that produces a hydrogen-rich gas from hydrocarbon fuels. Hydrogen production via autothermal reforming (ATR) is particularly attractive for applications that demand a quick start-up and response time in a compact size. However, further research is required to optimize the performance of autothermal reformers and accurate models of reactor performance must be developed and validated. The design includes the requirement of accommodating a wide range of experimental set ups. Factors considered in the design of the reformer are capability to use multiple fuels, ability to vary stoichiometry, precise temperature and pressure control, implementation of enhancement methods, capability to implement variable catalyst positions and catalyst arrangement, ability to monitor and change reactant mixing, and proper implementation of data acquisition. A model of the system was first developed in order to calculate flowrates, heating, space velocity, and other important parameters needed to select the hardware that comprises the reformer. Predicted performance will be compared to actual data once the reformer construction is completed. This comparison will quantify the accuracy of the model and should point to areas where further model development is required. The end result will be a research tool that allows engineers to optimize hydrogen production via autothermal reformation.

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Numerical Analysis of Steam-methane Reforming Reaction for Hydrogen Generation using Catalytic Combustion (촉매 연소를 열원으로 한 수증기-메탄개질반응 전산유체해석)

  • Lee, Jeongseop;Lee, Kanghoon;Yu, Sangseok;Ahn, Kookyoung;Kang, Sanggyu
    • Transactions of the Korean hydrogen and new energy society
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    • v.24 no.2
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    • pp.113-120
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    • 2013
  • A steam reformer is a chemical reactor to produce high purity hydrogen from fossil fuel. In the steam reformer, since endothermic steam reforming is heated by exothermic combustion of fossil fuel, the heat transfer between two reaction zones dominates conversion of fossil fuel to hydrogen. Steam Reforming is complex chemical reaction, mass and heat transfer due to the exothermic methane/air combustion reaction and the endothermic steam reforming reaction. Typically, a steam reformer employs burner to supply appropriate heat for endothermic steam reforming reaction which reduces system efficiency. In this study, the heat of steam reforming reaction is provided by anode-off gas combustion of stationary fuel cell. This paper presents a optimization of heat transfer effect and average temperature of cross-section using two-dimensional models of a coaxial cylindrical reactor, and analysis three-dimensional models of a coaxial cylindrical steam reformer with chemical reaction. Numerical analysis needs to dominant chemical reaction that are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming(DSR) reaction. The major parameters of analysis are temperature, fuel conversion and heat flux in the coaxial reactor.

Research of High Efficiency Integrated Reforming System Using Separated Reforming System (분리형 개질기를 이용한 고효율 일체형 개질기 개발에 관한 연구)

  • PARK, SANG-HYOUN;KIM, CHUL-MIN;SON, SUNG-HYO;JANG, SE-JIN;KIM, JAE-DONG;BANG, WAN-KEUN;LEE, SANG-YONG
    • Transactions of the Korean hydrogen and new energy society
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    • v.29 no.1
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    • pp.11-18
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    • 2018
  • A high efficiency integrated reforming system for improving the efficiency of the 5 kW PEMFC system used as the back up power of building was studied. The separated reforming system consisted of three parts - A steam reformer with two stage concentric circular shape, a heat exchanger type steam generator and a CO shift reactor. Temperature and steam carbon ratio (SCR) were control variables during operation. The operating conditions were optimized based on the thermal efficiency of the steam reformer as reformate gas composition changes at different temperature. In experiments, water was fully vaporized in the steam generator up to SCR 3.5 and the maximum thermal efficiency was achieved at the operating temperature around $700^{\circ}C$ in the steam reforming reactor. With the results of the separated reforming system research, we improved the shape of high efficiency integrated reformer. The performance evaluation of the integrated reformer was based on optimized operating conditions in SCR 3.5. As a result, the developed integrated reforming system maintained an efficiency of 76% and constant performance over 3,000 hours.

Efficiency Analysis of Compact Type Steam Reformer (컴팩트형 수증기 개질장치 효율분석)

  • Oh, Young-Sam;Song, Taek-Yong;Baek, Young-Soon;Choi, Lee-Sang
    • Transactions of the Korean hydrogen and new energy society
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    • v.13 no.4
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    • pp.304-312
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    • 2002
  • In this study, the performance of the $5Nm^3/hr$ compact type steam reformer which was developed for application of fuel cell or hydrogen station was evaluated in terms of gas process efficiency. For these purposes, reforming efficiency and total efficiency with system load change were analyzed. The reforming efficiency was calculated from the total molar flow of hydrogen output over total fuel flow input to the reformer and the burner on the higher heating value(HHV). In the case of the total efficiency, recovered heat at the heat recovery exchanger was considered. From the results, it was known that system performance was stable, because methane conversion showed the a slight decline which is about 2% though increasing system load to full. Reforming efficiency was increased from 20% to 58%, respectively as increasing system load from 10% to 90%. It was found that total efficiency was higher then reforming efficiency because of terms of heat recovered. As a results, it was known that total efficiency was increased form 75% to 83% at the 10% and 90% system load, respectively. From these results, it is concluded that compact steam reformer which is composed of stacking plate-type reactors is suitable to on-site hydrogen generator or to fuel cell application because of quick start within 1 hr and good performance.

Operational Characteristics of Methanol Reformer for the Phosphoric Acid Fuel Cell System (인산형 연료전지용 메탄올 연료개질기의 운전 특성)

  • 정두환;신동열;임희천
    • Journal of Energy Engineering
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    • v.2 no.2
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    • pp.200-207
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    • 1993
  • A methanol reformer was designed and fabricated using a CuO-ZnO low temperature shift catalyst, and its operation characteristics have been studied for the phosphoric acid fuel cell (PAFC) power generation system. The type of reactor was annular Methanol was consumed both for heating and for reforming fuel. Contents of carbon monoxide produced from the reformer increased as the reaction temperatures increased, but decreased as the mole ratios of water to methanol(H$_2$O/CH$_3$OH) increased. At steady state operating conditional, temperature profile of the catalytic reactor of the reformer was well coincide with the model equation, and it took 50 minutes from start to the rated condition of the reformer. When the system was operated at 4/4 and 1/4 of load, thermal efficiencies of the system were 72.3% and 77%, respectively. When the PAFC system was operated with reformed gas in the range of 62 V-37.6 V and 0-147 A, the trend of I-V curve showed a typical fuel tell characteristic. At steady state condition, the flow rates of reforming and combustion methanol were 88.1 mol/h and 50.1 mol/h, respectively.

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Surface Flame Patterns and Stability Characteristics of Premixed Burner System for Fuel Reformers (개질기용 예혼합 버너의 화염형태 및 안정성 특성)

  • Lee, Pil-Hyong;Park, Bong-Il;Jo, Soon-Hye;Hwang, Sang-Soon
    • Journal of the Korean Society of Combustion
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    • v.15 no.3
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    • pp.8-14
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    • 2010
  • Fuel processing systems which convert fuel into rich gas (such as stream reforming, partial oxidation, autothermal reforming) need high temperature environment ($600{\sim}1,000^{\circ}$). Generally, anode-off gas or mixture of anode-off gas and LNG is used as input gas of fuel reformer. In order to make efficient and low emission burner system for fuel reformer, it is necessary to elucidate the combustion and emission characteristic of fuel reformer burner. The purpose of this study is to develop a porous premixed flat ceramic burner that can be used for 1~5 kW fuel cell reformer. Ceramic burner experiments using natural gas, hydrogen gas, anode off gas, mixture of natural gas & anode off gas were carried out respectively to investigate the flame characteristics by heating capacity and equivalence ratio. Results show that the stable flat flames can be established for natural gas, hydrogen gas, anode off gas and mixture of natural gas & anode off gas as reformer fuel in the porous ceramic burner. For all of fuels, their burning velocities become smaller as the equivalence ratio goes to the lean mixture ratio, and a lift-off occurs at lean limit. Flame length in hydrogen and anode off gas became longer with increasing the heat capacity. In particular, the blue surface flame is found to be very stable at a very lean equivalence ratio at heat capacity and different fuels. The exhausted NOx and CO measurement shows that the blue surface flame represents the lowest NOx and CO emissions since it remains very stable at a lean equivalence ratio.

The Effect of Operating Conditions on the Heat-flow Characteristics and Reforming Efficiency of Steam Reformer with Combustor (연소기가 장착된 수증기 개질기에서 운전조건이 열유동 특성 및 개질효율에 미치는 영향)

  • Kim, Ji-Seok;Lee, Jae-Seong;Kim, Ho-Young
    • Journal of the Korean Society of Combustion
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    • v.16 no.1
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    • pp.36-45
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    • 2011
  • The heat-flow characteristics and reforming efficiency of steam reformer with combustor are numerically investigated at various operating conditions. SCR(Steam to Carbon Ratio) and GHSV(Gas Hourly Space Velocity) are adopted as important operating conditions. User-Defined-Function(UDF) was used to simultaneously calculate reforming and combustion reaction. Numerical results show that hot burned gas rise by a buoyant force and heat exchange between reforming reactors and cocurrent flow occurs in the combustion region. The results also indicate that an increase of SCR leads to decrease the mole fraction of hydrogen at the reactor outlet. As GHSV increases, conversion rate decreases.