scholarly journals Effect of Burner Operation on the Catalyst Tube Lifetime of a Steam Methane Reformer: A Numerical Study

2020 ◽  
Vol 11 (1) ◽  
pp. 231
Author(s):  
Chun-Lang Yeh
Keyword(s):  
Numerical Study ◽  
Operating Mode ◽  
Hydrogen Yield ◽  
Steam Methane ◽  
Flow Development ◽  
Real Model ◽  
Experimental Values ◽  
Burner Operation ◽  
Operation Risk ◽  
Downstream Area

In this paper, the catalyst tube lifetime of a practical steam methane reformer is analyzed numerically. The effect of burner operating mode on the flow development, hydrogen yield, and catalyst tube lifetime is discussed, with the aim of improving the reformer performance. The results of this study reveal that using the periodic boundary conditions, the temperatures and hydrogen yields obtained are much lower than the experimental values and the pressures are much lower than those using the real model. This results in overestimating the catalyst tube lifetime and underestimating the reformer operation risk. The catalyst tubes in the downstream area have longer lifetimes, while those in the upstream area have shorter lifetimes. Turning the upstream burners off is more efficient to the catalyst tube lifetime, while turning off the central groups of burners is less efficient. The main drawback of turning off burners is the decrease of hydrogen yield.

scholarly journals Numerical Study of the Velocity Decay of Offset Jet in a Narrow and Deep Pool

Water ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 59 ◽  
Author(s):  
Xin Li ◽  
Maolin Zhou ◽  
Jianmin Zhang ◽  
Weilin Xu
Keyword(s):  
Flow Field ◽  
Numerical Study ◽  
Expansion Ratio ◽  
Sudden Expansion ◽  
Mean Velocity ◽  
Cross Sectional ◽  
Potential Core ◽  
Early Region ◽  
Flow Development ◽  
Offset Jet

The present study examines the configuration of an offset jet issuing into a narrow and deep pool. The standard k-ε model with volume-of-fluid (VOF) method was used to simulate the offset jet for three exit offset ratios (OR = 1, 2 and 3), three expansion ratios (ER = 3, 4 and 4.8), and different jet exits (circular and rectangular). The results clearly show significant effects of the circumference of jet exits (Lexit) in the early region of flow development, and a fitted formula is presented to estimate the length of the potential core zone (LPC). Analysis of the flow field for OR = 1 showed that the decay of cross-sectional streamwise maximum mean velocity (Um) in the transition zone could be fitted by power law with the decay rate n decreased from 1.768 to 1.197 as the ER increased, while the decay of Um for OR = 2 or 3 was observed accurately estimated by linear fit. Analysis of the flow field of circular offset jet showed that Um for OR = 2 decayed fastest due to the fact that the main flow could be spread evenly in floor-normal direction. For circular jets, the offset ratio and expansion ratio do not affect the spread of streamwise velocity in the early region of flow development. It was also observed that the absence of sudden expansion of offset jet is analogous to that of a plane offset jet, and the flow pattern is different.

scholarly journals Numerical Investigation of the Effects of Steam Mole Fraction and the Inlet Velocity of Reforming Reactants on an Industrial-Scale Steam Methane Reformer

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2082
Author(s):  
Chun-Lang Yeh
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Mole Fraction ◽  
Production Control ◽  
Industrial Scale ◽  
Hydrogen Yield ◽  
Tube Surface ◽  
Inlet Velocity ◽  
Steam Methane ◽  
Wall Shear

Steam methane reforming (SMR) is the most common commercial method of industrial hydrogen production. Control of the catalyst tube temperature is a fundamental demand of the reformer design because the tube temperature must be maintained within a range that the catalysts have high activity and the tube has minor damage. In this paper, the transport and chemical reaction in an industrial-scale steam methane reformer are simulated using computational fluid dynamics (CFD). Two factors influencing the reformer temperature, hydrogen yield and stress distribution are discussed: (1) the mole fraction of steam (YH2O) and (2) the inlet velocity of the reforming reactants. The purpose of this paper is to get a better understanding of the flow and thermal development in a reformer and thus, to make it possible to improve the performance and lifetime of a steam reformer. It is found that the lowest temperature at the reforming tube surface occurs when YH2O is 0.5. Hydrogen yield has the highest value when YH2O is 0.5. The wall shear stress at the reforming tube surface is higher at a higher YH2O. The surface temperature of a reforming tube increases with the inlet velocity of the reforming reactants. Finally, the wall shear stress at the reforming tube surface increases with the inlet velocity of the reforming reactants.

scholarly journals Numerical study of H2S-H2O-air mixture conversion to hydrogen via activation of air by an electric discharge

2018 ◽  
Vol 209 ◽  
pp. 00015
Author(s):  
Ilya Arsentiev ◽  
Vera Savelieva ◽  
Nataliya Titova
Keyword(s):  
Mole Fraction ◽  
Electrical Discharge ◽  
Flow Reactor ◽  
Numerical Study ◽  
Energy Requirement ◽  
Plug Flow ◽  
Relative Yield ◽  
Hydrogen Yield ◽  
Input Energy ◽  
Specific Energy Requirement

The numerical analysis of H2 production during partial oxidation of H2S–H2O–air in a plug-flow reactor at a rather low temperature (T 0=500 K) was conducted. For the reforming process promotion, the oxidizer (air) was activated by an electrical discharge with different values of reduced electric field E/N and input energy E s. It was shown that a significant hydrogen yield in a flow reactor can be obtained only after mixture ignition. The ignition delay length turned out to be minimal at E/N~4–10 and 120–150 Td, when O2(a1Δg) mole fraction in the discharge products is maximal. If the H2S–H2O–air mixture ignites inside the flow reactor, the H2 mole fraction and its relative yield do not depend on E/N. The relative hydrogen yield increases monotonically with an increase of H2O amount. The specific energy requirement for H2 production in considered process was evaluated.

Modeling of a Nickel-based Fluidized Bed Membrane Reactor for Steam Methane Reforming Process

2019 ◽  
Vol 41 (2) ◽  
pp. 219-219
Author(s):  
Mustafa Kamal Pasha Mustafa Kamal Pasha ◽  
Iftikhar Ahmad Iftikhar Ahmad ◽  
Jawad Mustafa Jawad Mustafa ◽  
Manabu Kano Manabu Kano
Keyword(s):  
Fluidized Bed ◽  
Membrane Reactor ◽  
Operating Conditions ◽  
Methane Reforming ◽  
Hydrogen Yield ◽  
Reactor Model ◽  
Membrane Area ◽  
Steam Methane Reforming ◽  
Steam Methane ◽  
Process Simulator

Hydrogen being a green fuel is rapidly gaining importance in the energy sector. Steam methane reforming is one of the most industrially important chemical reaction and a key step in the production of high purity hydrogen. Due to inherent deficiencies of conventional reforming reactors, a new concept based on fluidized bed membrane reactor is getting the focus of researchers. In this work, a nickel-based fluidized bed membrane reactor model is developed in the Aspen PLUSand#174; process simulator. A user-defined membrane module is embedded in the Aspen PLUSand#174; through its interface with Microsoftand#174; Excel. Then, a series combination of Gibbs reactors and membrane modules are used to develop a nickel-based fluidized bed membrane reactor. The model developed for nickel-based fluidized bed membrane reactor is compared with palladium-based membrane reactor in terms of methane conversion and hydrogen yield for a given panel of major operating parameters. The simulation results indicated that the model can accurately predict the behavior of a membrane reactor under different operating conditions. In addition, the model can be used to estimate the effective membrane area required for a given rate of hydrogen production.

513 Numerical Study on Flow Development between Two-Concentric Rotating Cylinders

2001 ◽  
Vol 2001.50 (0) ◽  
pp. 275-276
Author(s):  
Masae Aoki ◽  
Takashi Watanabe ◽  
Hiroyuki Furukawa ◽  
Ikuo Nakamura
Keyword(s):  
Numerical Study ◽  
Rotating Cylinders ◽  
Flow Development

Modeling of Autothermal Steam Methane Reforming in a Fluidized Bed Membrane Reactor

2002 ◽  
Vol 1 (1) ◽  
Author(s):  
Meltem Dogan ◽  
Dusko Posarac ◽  
John Grace ◽  
Alaa-Eldin M. Adris ◽  
C. Jim Lim
Keyword(s):  
Fluidized Bed ◽  
Porous Alumina ◽  
Fluidized Bed Reactors ◽  
Methane Reforming ◽  
Hydrogen Yield ◽  
Flux Tubes ◽  
Steam Methane Reforming ◽  
Steam Methane ◽  
Membrane Surfaces ◽  
Reforming Reactions

Fluidized bed reactors for steam methane reforming, with and without immersed membrane surfaces for withdrawal of hydrogen, are modeled with oxygen added in order to provide the endothermic heat required by the reforming reactions. Porous alumina, palladium and palladium-coated high-flux tubes are investigated as separation materials, the latter two being permselective. Hydrogen yield and permeate hydrogen molar flow are predicted to decrease with increasing oxygen flow, and to increase with temperature. When the steam-to-carbon ratio increases, permeate hydrogen yield decreases slightly, while the total hydrogen yield increases for all configurations. The flow of oxygen required to achieve autothermal conditions depends on such factors as the reactor temperature, steam-to-carbon ratio and preheating of the feed.

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