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Book Simulation of Millisecond Catalytic Partial Oxidation of Methane in a Monolithic Reactor for the Production of Hydrogen Using Finite Element Methods

Download or read book Simulation of Millisecond Catalytic Partial Oxidation of Methane in a Monolithic Reactor for the Production of Hydrogen Using Finite Element Methods written by Julie Flynn and published by . This book was released on 2006 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: "The model shows high yields of hydrogen from methane and air which fits the experimental results in most of the cases. It also fits qualitatively the transient results. The influence of the kinetics was investigated and it is the principle limitation of the model which leads to a poor quantitative description." --

Book Simulation of Millisecond Catalytic Partial Oxidation of Methane

Download or read book Simulation of Millisecond Catalytic Partial Oxidation of Methane written by Julie Flynn and published by LAP Lambert Academic Publishing. This book was released on 2015-04-21 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogen can be the key solution of all our energy needs in the future and to face climate change while reducing greenhouse gases. Syngas, H2 and CO, is industrially produced by steam reforming of methane. A potential alternative is the catalytic partial oxidation of methane. The process is fast, exothermic and auto-thermal.A dual sequential bed catalyst is used, which makes use of a combustion catalyst followed by a reforming catalyst in order to carry out catalytic partial oxidation in two steps.Numerical simulations using finite elements methods coupled with global kinetics are performed to have a better understanding of the transient process and the solid and gas temperature profiles in a catalyst. The results include temporal and spatial reactant conversion, product selectivity, and temperature profiles in the catalyst. Where possible simulation results are compared to experimental data. The model shows high yields of hydrogen from methane and air which fits the experimental results in most of the cases. It also fits qualitatively the transient results.

Book Catalytic Partial Oxidation of Methane at High Flowrates

Download or read book Catalytic Partial Oxidation of Methane at High Flowrates written by Keith Lawrence Hohn and published by . This book was released on 1999 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Simulation of Hydrogen Generation from Methane Partial Oxidation in a Plasma Fuel Reformer

Download or read book Simulation of Hydrogen Generation from Methane Partial Oxidation in a Plasma Fuel Reformer written by Nuria Margarit Bel and published by . This book was released on 2005 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: A model for the chemistry in a plasma fuel reformer or plasmatron has been developed. The plasma fuel reformer is set up to produce syngas (hydrogen and carbon monoxide gas mixture) from partial oxidation of hydrocarbons. The behavior of methane as fuel has been investigated to characterize and simulate the plasmatron performance. The goal of this work has been improved understanding of the physical/chemical processes within the reactor. The simulation tool used was CHEMKIN 3.7, using the GRI methane combustion mechanism. The Partially Stirred Reactor application (PASR) simulates random mixing by a frequency mixing parameter, which is directly dependant of the system fluid dynamic properties. The fuel reformer was designed as a reactor where combustion is initiated by an electric discharge due to ohmic heating of the arc region. From discharge observations, energy estimations and model simulations, it was found that the electric arc initiates combustion by locally raising the temperature and then propagating the reaction by heat and mass transfer/mixing to the surroundings. Simulation results demonstrated that there is an optimum characteristic mixing time for each residence time, depending on the initial temperature reached at the arc. It was also found that for given power input into the system, the more spread the energy is, or the more mass is heated to a moderate temperature, the better the calculated performance.

Book Modelling and Experimental Study of Methane Catalytic Cracking as a Hydrogen Production Technology

Download or read book Modelling and Experimental Study of Methane Catalytic Cracking as a Hydrogen Production Technology written by Ashraf Mukhtar Lotfi Amin and published by . This book was released on 2011 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Production of hydrogen is primarily achieved via catalytic steam reforming, partial oxidation, and auto-thermal reforming of natural gas. Although these processes are mature technologies, they are somewhat complex and CO is formed as a by-product, therefore requiring a separation process if a pure or hydrogen-rich stream is needed. As an alternative method, supported metal catalysts can be used to catalytically decompose hydrocarbons to produce hydrogen. The process is known as catalytic cracking of hydrocarbons. Methane, the hydrocarbon containing the highest percentage of hydrogen, can be used in such a process to produce a hydrogen-rich stream. The decomposition of methane occurs on the surface of the active metal to produce hydrogen and filamentous carbon. As a result, only hydrogen is produced as a gaseous product, which eliminates the need of further separation processes to separate CO2 or CO. Nickel is commonly used in research as a catalyst for methane cracking in the 500-700C temperature range. To conduct methane catalytic cracking in a continuous manner, regeneration of the deactivated catalyst is required and circulation of the catalysts between cracking and regeneration cycles must be achieved. Different reactor designs have been successfully used in cyclic operation, such as a set of parallel fixed-bed reactors alternating between cracking and regeneration, but catalyst agglomeration due to carbon deposition may lead to blockage of the reactor and elevated pressure drop through the fixed bed. Also poor heat transfer in the fixed bed may lead to elevated temperature during the regeneration step when carbon is burned in air, which may cause catalyst sintering. A fluidized bed reactor appears as a viable option for methane catalytic cracking, since it would permit cyclic operation by moving the catalyst between a cracker and a regenerator. In addition, there is the possibility of using fine catalyst particles, which improves catalyst effectiveness. The aims of this project were 1) to develop and characterize a suitable nickel-based catalyst and 2) to develop a model for thermal catalytic decomposition of methane in a fluidized bed.

Book Numerical Simulation of Micro Mini Channel Based Methane Steam Reformer

Download or read book Numerical Simulation of Micro Mini Channel Based Methane Steam Reformer written by Daniel Alan Peterson and published by . This book was released on 2010-06-29 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerical modeling of methane-steam reforming is performed in a micro/mini-channel with heat input through catalytic channel walls. The low-Mach number, variable density Navier-Stokes equations together with multicomponent reactions are solved using a parallel numerical framework. Methane-steam reforming is modeled by three reduced-order reactions occurring on the reactor walls. The surface reactions in the presence of a catalyst are modeled as Neumann boundary conditions to the governing equations. Two catalysts are investigated: a porous Nickel substrate and a porous felt with deposited Palladium nanoparticles. The reduced-order mechanism kinetics model is coupled with the flow solver to resolve the chemical species field within the reactor geometry. The effects of the total heat input, heat flux profile, flow rate and inlet steam-methane molar concentration on production of hydrogen are investigated in detail.The results of the parametric study give performance evaluations. An increase of hydrogen production of 10% (molar fraction) is observed when increasing the heat flux from no heat flux to a wall heat flux of 3 kW/m^2. The results from the three heat flux profiles study (constant, linear increasing, and linear decreasing) are increased hydrogen production between the linear decreasing profile (worst performer) and the linear increasing profile (best performer) of 3.5% on a molar basis. Varying flow rate from 800 ml/min to 100 ml/min results in an increase of hydrogen mole fraction of 16%. Hydrogen production is non-linearly related to the steam-methane ratio. Maximum hydrogen production is observed near a ratio of 3.0. The reactions are diffusion limited. The diffusion limitations may be reduced by the introduction of hydrogen extraction or mixing flow.

Book Partial Oxidation of Methane

Download or read book Partial Oxidation of Methane written by Sunil Agarwalla and published by . This book was released on 1991 with total page 356 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Modellization of a Microreactor for the Catalytic Partial Oxidation of Methane

Download or read book Modellization of a Microreactor for the Catalytic Partial Oxidation of Methane written by Pierre Hakizimana and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Conversion of methane and carbon dioxide, which are two of the cheapest and most abundant carbon-containing materials, into useful products is an important area of current catalytic research. This reaction has also very important environmental implications because both methane and carbon dioxide are greenhouse gases which may be converted into valuable feedstock. The aim of this work is to propose a catalytic reactor design for the conversion of methane and carbon dioxide. In this sense, simulations will be carried out from Ansys® software by means of Fluent CFD models. Then, a sensitive analysis will be performed to study the influence of flowrate, reactant ratio, pressure and temperature on the reaction conversion and selectivity profiles. Finally, a reactor prototype and optimum operational conditions will be proposed.

Book Methane Conversion by Oxidative Processes

Download or read book Methane Conversion by Oxidative Processes written by Eduardo E. Wolf and published by Springer. This book was released on 1992 with total page 566 pages. Available in PDF, EPUB and Kindle. Book excerpt: A reasonable case could be made that the scientific interest in catalytic oxidation was the basis for the recognition of the phenomenon of catalysis. Davy, in his attempt in 1817 to understand the science associated with the safety lamp he had invented a few years earlier, undertook a series of studies that led him to make the observation that a jet of gas, primarily methane, would cause a platinum wire to continue to glow even though the flame was extinguished and there was no visible flame. Dobereiner reported in 1823 the results of a similar investigation and observed that spongy platina would cause the ignition of a stream of hydrogen in air. Based on this observation Dobereiner invented the first lighter. His lighter employed hydrogen (generated from zinc and sulfuric acid) which passed over finely divided platinum and which ignited the gas. Thousands of these lighters were used over a number of years. Dobereiner refused to file a patent for his lighter, commenting that "I love science more than money." Davy thought the action of platinum was the result of heat while Dobereiner believed the ~ffect ~as a manifestation of electricity. Faraday became interested in the subject and published a paper on it in 1834; he concluded that the cause for this reaction was similar to other reactions.

Book Numerical Modeling of Methane Decomposition for Hydrogen Production in a Fluidized Bed Reactor

Download or read book Numerical Modeling of Methane Decomposition for Hydrogen Production in a Fluidized Bed Reactor written by Maryam Younessi Sinaki and published by . This book was released on 2014 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: The decomposition of methane for hydrogen production is an attractive alternative to the established method of reforming. This process considerably reduces the emission of greenhouse gases, and its overall efficiency and cost are competitive. The decomposition of methane is performed with a catalyst to produce a substantial amount of hydrogen, and decrease the operating temperature. Between different catalysts available, carbon is selected in this study due to its low rate of decay and advantages such as low cost and availability. Also, a fluidized bed reactor operating in the particulate regime is employed due to the efficient contact between the catalyst and the gas. Consequently, hydrogen production from the thermocatalytic decomposition of methane in a particulate fluidized bed reactor of carbon particles is investigated. To obtain an appropriate design and operation for this process, the effect of different operating parameters and catalyst properties should be investigated on the performance. This aim can be achieved by modeling. A number of models with different complexities have been proposed for this process. Considering the objective of this thesis, a complex kinetic model is required to represent the effect of the catalyst properties. In literature, the kinetics is generally modeled with a global equation using experimental parameters. Since investigation on the effect of the properties of the catalyst is not feasible with this method, the detailed kinetic model with a surface reaction mechanism is employed in this study. Investigation on this surface mechanism is very limited, and only one of the models available in literature is determined to be appropriate. Nevertheless, this model has some important drawbacks. The major problem is that the specific surface area is considered as the only catalyst property affecting the activity of carbon. Experimental studies suggest that the activity of this catalyst is a function of its specific surface area and number of active sites, and neglecting either of these properties can lead to a high inaccuracy. Consequently, a new kinetic model is developed where a modified form of the available mechanism is used, and the number of active sites and the specific surface area of the catalyst are considered in the rate equations. It is noted that although several experimental investigations have been performed on the origin of the active sites, their quantity has not been acceptably determined yet. A method is presented in this study to estimate the number of active sites with the developed model and experimental data. To the best knowledge of the author, this is the first model to incorporate the effect of this parameter for carbon catalysts in the decomposition of methane and quantify its value. Another important problem of the model available in literature is its dependency on experimental measurements for determining the hydrodynamic characteristics of the fluidized bed. In this study, the hydrodynamics of the reactor is modeled with empirical correlations to obtain a complete representation of the process within the required accuracy, with minimal experimental requirements. The model is used to investigate the effect of different operating parameters and catalyst properties on the amount of the initial methane conversion. The operating parameters studied are the temperature, residence time, gas velocity, and composition of the feed gas. The catalyst properties considered are the particle size and pore volume, the number of active sites, and the percentage of fine particles in the bed. The effect of the variations of each of these factors in a certain range is investigated for a fluidized bed reactor operating at the onset of fluidization at nominal condition. The onset of fluidization is maintained by changing the inlet flow rate in a reactor of a specific size. The results show that, considering the range of variations in this study, the procedures that cause the highest improvement in conversion are: increasing the residence time, decreasing the size of particles, adding fine particles to the bed, increasing the temperature, using catalysts with high surface areas or large number of active sites, changing the inlet gas composition, and using catalysts with large pore volumes, respectively. It is noted that all of these improvements are associated with higher initial or operating costs. Therefore, changing each of these factors beyond a certain value is faced with economic and technical barriers. Consequently, the possibility and efficiency of using two factors simultaneously for achieving higher conversions was also investigated. The results can be used as a guideline to choose between several catalysts considering their characteristics, or to suggest appropriate operating conditions.

Book Modeling Catalytic Methane Partial Oxidation with Detailed Chemistry

Download or read book Modeling Catalytic Methane Partial Oxidation with Detailed Chemistry written by Daniela Dalle Nogare and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: