Author: Yun YangPublisher:
ISBN:
Category :
Languages : en
Pages : 123
Book Description
Methane Conversion and Reforming by Atmospheric Pressure Non-thermal Plasma
Author: Yun YangNon-thermal Plasma Discharges for Methane Reforming
Author: Pablo Diaz Gomez MaqueoPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
"This thesis presents the experimental study of non-thermal plasmas applied to methane reforming at atmospheric pressure. The resulting hydrogen-containing gas is studied as a potential fuel additive to increase chemical reactivity in gas turbine engine conditions. Reactivity control is proposed as a fuel flexibility technology for low calorific fuels and as a mean to operate in low emission conditions such as lean premixed combustion.The experimental section of the thesis is focused on the characterization of pulsed-powered non-thermal discharge plasmas as fuel reformers. The experimental reactor consists of a pin to plane plasma chamber designed to be optically accessible and to isolate the reacting gases from the surrounding air. The applied voltage pulse duration is on the order of 100 ns to prevent thermalization of the plasma channel and to decouple thermal energy from excitation energy delivered by the discharge. When a voltage pulse is applied to the pin electrode, two stable regimes are identified: a diffuse regime with a plasma that occupies most of the inter-electrode volume, and a filamentary regime with constricted spark-like filaments. The first regime operates at a maximum energy per pulse of 1.3 mJ with negligible conversion efficiency. On the contrary, the filamentary regime reaches a maximum energy per pulse of 13.9 mJ with conversion and energy efficiencies of 26.3 % and 19.7 % respectively. Both regimes have gas temperatures estimated to be near 500 K, and there is no correlation with respect to the energy per pulse. The results suggest that the more energetic filamentary regime is not heating the gas, but rather delivering the energy towards better conversion efficiencies.To study the individual contributions of reactant temperature, pulse repetition frequency, and energy per pulse on the reforming performance of the reactor, a new high voltage pulser was developed and a preheating system capable of reaching 800 K was added. Temperature estimations show that varying the energy per pulse has a minimal effect on the temperature of the gas, while increasing the frequency heats the gas up to 777 K. Increasing reactant temperature is shown to have a negligible effect, while increasing the pulse repetition frequency has the strongest effect on conversion and energy efficiency. Additionally, the best performance is observed in partial oxidation, reaching a maximum conversion efficiency of 68.2 % and an energy efficiency of 31.5 %.The obtained results demonstrate the applicability of nanosecond repetitively-pulsed discharges as methane reformers. Capable of producing mixtures with up to 29.7 % hydrogen, these discharges can be used to increase chemical reactivity in gas turbine engine conditions as shown by the numerical simulations. This conversion is not dependent on the reactant temperature, but rather on the total amount of energy deposited by the discharge. Additionally, increasing the repetition frequency of the discharge seems to have the largest increase in efficiency, pointing towards future optimization of plasma-assisted fuel reforming technologies." --
Plasma Catalysis
Author: Annemie BogaertsPublisher: MDPI
ISBN: 3038977500
Category : Technology & Engineering
Languages : en
Pages : 248
Book Description
Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.
Plasma Chemistry and Gas Conversion
Author: Nikolay BritunPublisher: BoD – Books on Demand
ISBN: 1789848407
Category : Science
Languages : en
Pages : 88
Book Description
Low-temperature non-equilibrium gaseous discharges represent nearly ideal media for boosting plasma-based chemical reactions. In these discharges the energy of plasma electrons, after being received from the electromagnetic field, is transferred to the other degrees of freedom differently, ideally with only a small part going to the translational motion of heavy gas particles. This unique property enables the important application of non-equilibrium plasmas for greenhouse gas conversion. While the degree of discharge non-equilibrium often defines the energetic efficiency of conversion, other factors are also of a great importance, such as type of discharge, presence of plasma catalysis, etc. This book is focused on the recent achievements in optimization and understanding of non-equilibrium plasma for gas conversion via plasma modeling and experimental work.
Methane Conversion
Author: D.M. BibbyPublisher: Elsevier
ISBN: 0080960707
Category : Technology & Engineering
Languages : en
Pages : 759
Book Description
This proceedings volume comprises the invited plenary lectures, contributed and poster papers presented at a symposium organised to mark the successful inauguration of the world's first commercial plant for production of gasoline from natural gas, based on the Mobil methanol-to-gasoline process. The objectives of the Symposium were to present both fundamental research and engineering aspects of the development and commercialization of gas-to-gasoline processes. These include steam reforming, methanol synthesis and methanol-to-gasoline. Possible alternative processes e.g. MOGD, Fischer-Tropsch synthesis of hydrocarbons, and the direct conversion of methane to higher hydrocarbons were also considered.The papers in this volume provide a valuable and extremely wide-ranging overview of current research into the various options for natural gas conversion, giving a detailed description of the gas-to-gasoline process and plant. Together, they represent a unique combination of fundamental surface chemistry catalyst characterization, reaction chemistry and engineering scale-up and commercialization.
Nonthermal Plasma Microreaction Engineering for Gas and Liquid Processing
Author: Justin PommerenckPublisher:
ISBN:
Category : Activation (Chemistry)
Languages : en
Pages : 154
Book Description
Atmospheric pressure plasma is non-thermal at millimeter to micrometer separations. It represents an alternative low exergy initiator of many chemical reactions. In many instances heat, light or sound are not efficient providers of the necessary energy to overcome chemical activation barriers. The focus of this research is applying dc nonthermal plasma for gas and liquid chemical processing. The sub-millimeter dimensions offered by microtechnology are utilized to activate the majority of the gas or liquid stream. This enhances conversion, product yield and process efficiency. The first reported sustained dc emission from arrays of micro-emitter electrodes is contained within this thesis. This is the first formation of constant dc microcorona fields at atmospheric pressure in air and hydrocarbon gases. Methane is chemically converted in several microchannel devices to higher value products. A discovery that may lead to improved recoverability of stranded natural gas in our current energy cycle. Methane conversion to either C2 or C3 hydrocarbons of up to 80% with high selectivity are demonstrated. A finite element chemical engineering mathematical model for the hydrocarbon coupling reaction is developed. Plasma microreactors can also dry reform methane to synthesis gas. The feasibility of microplasma carbon dioxide dry reforming in a microreactor with a dc sustaining voltage under 1kV has been demonstrated. More than 60% conversion is achieved in the unoptimized reactor with nearly complete selectivity to synthesis gas. A plasma microchannel device can completely degrade representative trace toxic organic contaminants in a single pass. Rhodamine B is a colorimetric dye used as an example organic compound. A G[subscript 50%] factor, which represents the energy required to remove half of the starting contaminant, is tabulated for both a batch reactor and microchannel device. The plasma electrochemical activation of advanced oxidation chemistry converts from E-6 to E-11 moles per joule of input energy.
Dry Reforming of Methane Using Non-thermal Plasma-catalysis
Author: Helen J. GallonStudy of Methane Reforming in Warm Non-equilibrium Plasma Discharges
Author: Sreekar ParimiPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Utilization of natural gas in remote locations necessitates on-site conversion of methane into liquid fuels or high value products. The first step in forming high value products is the production of ethylene and acetylene. Non-thermal plasmas, due to their unique nonequilibrium characteristics, offer advantages over traditional methods of methane reforming. Different kinds of non-thermal plasmas are being investigated for methane reforming. Parameters of these processes like flow rate, discharge size, temperature and other variables determine efficiency of conversion. An efficient process is identified by a high yield and low specific energy of production for the desired product. A study of previous work reveals that higher energy density systems are more efficient for methane conversion to higher hydrocarbons as compared to low energy density systems. Some of the best results were found to be in the regime of warm discharges. Thermal equilibrium studies indicate that higher yields of ethylene are possible with an optimal control of reaction kinetics and fast quenching. With this idea, two different glow discharge reactor systems are designed and constructed for investigation of methane reforming. A counter flow micro plasma discharge system was used to investigate the trends of methane reforming products and the control parameters were optimized to get best possible ethylene yields while minimizing its specific energy. Later a magnetic glow discharge system is used and better results are obtained. Energy costs lower than thermal equilibrium calculations were achieved with magnetic glow discharge systems for both ethylene and acetylene. Yields are obtained from measurements of product concentrations using gas chromatography and power measurements are done using oscilloscope. Energy balance and mass balances are performed for product measurement accuracy and carbon deposition calculations. Carbon deposition is minimized through control of the temperature and residence time conditions in magnetic glow discharges. Ethylene production is observed to have lower specific energies at higher powers and lower flow rates in both reactors. An ethylene selectivity of 40% is achieved at an energy cost of 458MJ/Kg and an input energy cost of 5 MJ/Kg of methane.
Carbon Dioxide Chemistry, Capture and Oil Recovery
Author: Iyad KaraméPublisher: BoD – Books on Demand
ISBN: 178923574X
Category : Science
Languages : en
Pages : 268
Book Description
Fossil fuels still need to meet the growing demand of global economic development, yet they are often considered as one of the main sources of the CO2 release in the atmosphere. CO2, which is the primary greenhouse gas (GHG), is periodically exchanged among the land surface, ocean, and atmosphere where various creatures absorb and produce it daily. However, the balanced processes of producing and consuming the CO2 by nature are unfortunately faced by the anthropogenic release of CO2. Decreasing the emissions of these greenhouse gases is becoming more urgent. Therefore, carbon sequestration and storage (CSS) of CO2, its utilization in oil recovery, as well as its conversion into fuels and chemicals emerge as active options and potential strategies to mitigate CO2 emissions and climate change, energy crises, and challenges in the storage of energy.
Proceedings of the 5th International Symposium on Plasma and Energy Conversion
Author: Zhi FangPublisher: Springer Nature
ISBN: 9819722454
Category :
Languages : en
Pages : 725
Book Description