• Title, Summary, Keyword: Reformer

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Combustion Characteristic of Anode Off Gas for Fuel Cell Reformer (개질기용 Anode Off Gas의 연소특성에 관한 연구)

  • Lee, Pil Hyong;Hwang, Sang Soon
    • Journal of the Korean Society of Combustion
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    • v.17 no.4
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    • pp.5-10
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    • 2012
  • The reformer system is a chemical device that drives the conversion of hydrocarbon to hydrogen rich gas under high temperature environment($600-1,000^{\circ}C$). Generally, NG(Natural Gas) or AOG(Anode Off Gas) is used as fuel of fuel cell reformer combustion system. The experimental study to analyze the combustion characteristics of a premixed ceramic burner used for 0.5-1.0 kW fuel cell reformer was performed. Ceramic burner experiments using NG and AOG were carried out to investigate the flame stability characteristics by heating capacity, equivalence ratio and different fuels respectively. The results show that surface flames can be classified into green, red, blue and lift-off flames as the equivalence ratio of methane-air mixture decreases. And the stable flames can be established using NG and AOG as reformer fuel in the perforated ceramic burner. In particular, the blue flame is found to be stable at a lean equivalence ratio under different mixture conditions of NG and AOG for the 0.5 to 1.0 kW fuel cell system power range. NOx emission is under 60 ppm between 0.70 to 0.78 of equivalence ratio and CO emission is under 50 ppm between 0.70 to 0.84 of equivalence ratio.

Combustion Characteristics of Premixed Burner for Fuel Reformer (개질기용 예혼합 연소장치의 연소특성 연구)

  • Lee, Pil-Hyong;Lee, Jae-Young;Han, Sang-Seok;Park, Chang-Soo;Hwang, Sang-Soon
    • Proceedings of the KSME Conference
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    • pp.2181-2185
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    • 2008
  • Fuel processing systems which convert HC fuel into $H_2$ rich gas (such as stream reforming, partial oxidation, auto-thermal reforming) need high temperature environment($600-1000^{\circ}C$). 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 1-5kW fuel cell reformer. Ceramic burner experiments using natural gas, hydrogen 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 & anode off gas as reformer fuel. 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.

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Characteristics of LPG fuel Reforming in Plasma Reformer for Hydrogen Production (수소 생성을 위한 플라즈마 개질기에서의 LPG 연료의 개질 특성)

  • Park, Yunhwan;Lee, Deahoon;Kim, Changup;Kang, Kernyong
    • Journal of the Korean Institute of Gas
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    • v.17 no.6
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    • pp.8-14
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    • 2013
  • In this study, characteristics of the geometric design changes of plasma reformer for LPG fuelled vehicles were studied. To improve the yield of hydrogen, reformer 1st, and 2nd were designed. Secondary reformer compared to the primary reformer to increase the volume of the rear part of reformed gas having passed through the plasma and increased reaction time. To compare reforming results of two reformers, various experimental conditions such as, from partial oxidation to total oxidation conditions $O_2/C$ ratios, and total flow rate of 20, 30, 40, 50 lpm conditions, were varied. Results showed that with increasing $O_2/C$ ratios, LPG conversion rate increased, decreased hydrogen selectivity and hydrogen yield optimal point existed and secondary reformer 4.5 times larger than the primary reformer at the same flow rate to 4~14% increase in the yield of hydrogen.

Numerical Study on the Performance and the Heat Flux of a Coaxial Cylindrical Steam Reformer for Hydrogen Production (수소 생산을 위한 동축원통형 수증기 개질기의 성능 및 열유속에 대한 수치해석 연구)

  • Park, Joon-Guen;Lee, Shin-Ku;Bae, Joong-Myeon;Kim, Myoung-Jun
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.9
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    • pp.709-717
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    • 2009
  • Heat transfer rate is a very important factor for the performance of a steam reformer because a steam reforming reaction is an endothermic reaction. Coaxial cylindrical reactor is the reactor design which can improve the heat transfer rate. Temperature, fuel conversion and heat flux in the coaxial cylindrical steam reformer are studied in this paper using numerical method under various operating conditions. Langmuir-Hinshelwood model and pseudo-homogeneous model are incorporated for the catalytic surface reaction. Dominant chemical reactions are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming (DSR) reaction. Although coaxial cylindrical steam reformer uses 33% less amount of catalyst than cylindrical steam reformer, its fuel conversion is increased 10 % more and its temperature is also high as about 30 degree. There is no heat transfer limitation near the inlet area at coaxial-type reactor. However, pressure drop of the coaxial cylindrical reactor is 10 times higher than that of cylindrical reactor. Operating parameters of coaxial cylindrical steam reformer are the wall temperature, the inlet temperature, and the Gas Hourly Space Velocity (GHSV). When the wall temperature is high, the temperature and the fuel conversion are increased due to the high heat transfer rate. The fuel conversion rate is increased with the high inlet temperature. However, temperature drop clearly occurs near the inlet area since an endothermic reaction is active due to the high inlet temperature. When GHSV is increased, the fuel conversion is decreased because of the heat transfer limitation and short residence time.

Geometric Characteristics of Methane Steam Reforming with Low Temperature Heat Source (중저온 열원에 의한 메탄 수증기 개질의 형상 인자에 따른 특성)

  • Shin, Gahui;Yun, Jinwon;Yu, Sangseok
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.12
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    • pp.793-799
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    • 2016
  • In a hybrid fuel cell system, low-temperature reforming technology, which uses waste heat as a heat source, is applied to improve system efficiency. A low temperature reformer is required to optimize geometry in low thermal conditions so that the reformer can achieve the proper methane conversion rate. This study analyzed internal temperature distributions and the reaction patterns of a reformer by considering the change of the shape factor on the limited heat supply condition. Unlike the case of a high temperature reformer, analysis showed that the reaction of a low temperature reformer takes place primarily in the high temperature region of the reactor exit. In addition, it was confirmed that the efficiency can be improved by reducing the GHSV (gas hourly space velocity) or increasing the heat transfer area in the radial direction. Through reacting characteristic analysis, according to change of the aspect ratio, it was confirmed that a low temperature reformer can improve the efficiency by increasing the heat transfer in the radial direction, rather than in the longitudinal direction.

The Performance & Operation Analysis of a Steam Reformer for MCFC (MCFC용 Steam Reformer 개질성능 분석 및 운전평가)

  • Seo, Hai-Kung;Koh, Joon-Ho;Lim, Hee-Chun
    • Transactions of the Korean hydrogen and new energy society
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    • v.11 no.4
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    • pp.149-159
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    • 2000
  • This paper is concerned with the performence of a steam reformer for 25kW class MCFC, which is compared with the theoretically calculated results at various operating conditions. The theoretical $H_2$ production amount and $CH_4$ conversion rate are calculated with variations of temperature and steam/carbon (S/C) ratio using fortran program, and the actual values are measured from flowmeter and gas chromatography. As a result of the comparison of theoretical and actual values, the theoretical $H_2$ production amount is calculated by $24.4m^3/hr$ at the normal operating condition(LNG $9m^3/hr$, S/C ratio 5, absolute pressure $2.77kg/cm^2$, $610^{\circ}C$), but the actual production amount is only $19.4m^3/hr$, which is 79.5% of the theoretical value. Nevertheless, at the normal operating condition, the reformer for 25kW class MCFC performed well for a 2,100 hr long run operation, constantly producing $H_2$.

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The Performance & Operation Analysis of a Plate Type Reformet for 2 kW Class MCFC Stack (2 kW급 MCFC용 평편형 개질기 운전결과)

  • Seo, Hal-Kung;Ahn, Kyo-Sang;Lim, Hee-Chun;Lee, Sang-Deuk
    • Transactions of the Korean hydrogen and new energy society
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    • v.13 no.2
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    • pp.159-167
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    • 2002
  • The operation results of the 2kW class plate type reformer, which has several advantages compared with the tubular burner type reformer, are analyzed. This plate type reformer is composed of six combustion chambers and five reforming chambers by turns. The methane conversion rate at 1.6 absolute pressure is about 84%, which is reasonably similar to theoretical value, 85.3%. Though the abrupt interruption was made just by the carbon deposition during heating the fuel line to combustion chambers around 200 hours operation, the overall steady state operation is more than 450 hours. These operation results show the verification of long run performance and the possibility of direct connection between plate reformer and fuel cell stack.

Computational Fluid Dynamics Analysis of Plate Type Reformer for MCFC (용융탄산염 연료전지용 평판형 개질기 열유동 전산유체역학 해석)

  • Shin, Dong-Hoon;Seo, Hye-Gyung;Lim, Hee-Chun;Lee, Sang-Duk
    • Transactions of the Korean hydrogen and new energy society
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    • v.17 no.4
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    • pp.403-408
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    • 2006
  • The plate reformer consisting of combustion chamber and reforming chamber for 25 kW MCFC stack has been operated and computational fluid dynamics was applied to estimate reactions and thermal fluid behavior in the reformer. The methane air 2-stage reaction was assumed in the combustion chamber, and three step steam reforming reactions were included in the calculation. Flow uniformity, reaction rate and species distribution, and temperature distribution were analyzed. In particular, temperature distribution was compared with the measurements to show good agreement in the combustion chamber, however, inappropriate agreement in the reformer chamber.

A Study on the Optimum Design for LTCC Micro-Reformer: Design and performance evalution of monolith fuel reformer/PROX (LTCC를 소재로 하는 마이크로 리포머의 최적 설계에 관한 연구 ; 일체형 Reformer/PROX 반응기의 설계 및 성능평가)

  • Chung, C.H.;Oh, J.H.;Jang, J.H.;Jeong, M.K.
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • pp.615-616
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    • 2006
  • A micro-fuel processor system integrating steam reformer and partial oxidation reactor was manufactured using low temperature cofired ceramic (LTCC). A CuO/ZnO/$Al_2O_3$ catalyst and Pt-based catalyst prepared by wet impregnation were used for steam reforming and partial oxidation, respectively. The performance of the LTCC micro-fuel processor was measured at various operating conditions such as the effect of the feed flow rate, the ratio of $H_2O/CH_3OH$, and the operating temperature on the LTCC reformer and CO clean-up system. The catalyst layer was loaded with "Fill and Dry" coating for small volume. The product gas was composed of $70\sim75%$ hydrogen, $20\sim25%$ carbon dioxide, and $1\sim2%$ carbon monoxide at $250\sim300^{\circ}C$, respectively.

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