scholarly journals Reversible Molten Catalytic Methane Cracking Applied to Commercial Solar-Thermal Receivers

Energies ◽  
2020 ◽  
Vol 13 (23) ◽  
pp. 6229
Author(s):  
Scott C. Rowe ◽  
Taylor A. Ariko ◽  
Kaylin M. Weiler ◽  
Jacob T. E. Spana ◽  
Alan W. Weimer
Keyword(s):  
Flow Reactor ◽  
Plug Flow ◽  
Hydrogen Fuel ◽  
Reactor Model ◽  
Solar Reactor ◽  
Greenhouse Emissions ◽  
Solar Reactors ◽  
And Performance ◽  
Methane Cracking ◽  
Technology Demonstrator

When driven by sunlight, molten catalytic methane cracking can produce clean hydrogen fuel from natural gas without greenhouse emissions. To design solar methane crackers, a canonical plug flow reactor model was developed that spanned industrially relevant temperatures and pressures (1150–1350 Kelvin and 2–200 atmospheres). This model was then validated against published methane cracking data and used to screen power tower and beam-down reactor designs based on “Solar Two,” a renewables technology demonstrator from the 1990s. Overall, catalytic molten methane cracking is likely feasible in commercial beam-down solar reactors, but not power towers. The best beam-down reactor design was 9% efficient in the capture of sunlight as fungible hydrogen fuel, which approaches photovoltaic efficiencies. Conversely, the best discovered tower methane cracker was only 1.7% efficient. Thus, a beam-down reactor is likely tractable for solar methane cracking, whereas power tower configurations appear infeasible. However, the best simulated commercial reactors were heat transfer limited, not reaction limited. Efficiencies could be higher if heat bottlenecks are removed from solar methane cracker designs. This work sets benchmark conditions and performance for future solar reactor improvement via design innovation and multiphysics simulation.

A Kinetic Study of Hydrocarbons Reactivity on Palladium Catalysts through a DFT Approach

2001 ◽  
Vol 677 ◽  
Author(s):  
Valeria Bertani ◽  
Carlo Cavallotti ◽  
Maurizio Masi ◽  
Sergio Carrá
Keyword(s):  
Kinetic Study ◽  
Palladium Catalysts ◽  
Density Functional ◽  
Flow Reactor ◽  
Correlation Energy ◽  
Plug Flow ◽  
Kinetic Scheme ◽  
Atomic Scale ◽  
Basis Set ◽  
Reactor Model

ABSTRACTPalladium clusters have been chosen to represent a typical supported heterogeneous catalyst and their interaction with hydrocarbons has been investigated theoretically. The calculations were performed through density functional theory and the Becke-Lee-Yang-Parr hybrid (B3LYP) functional was adopted to calculate exchange and correlation energy. An effective core potential basis set (ECP on core electrons and Dunning/Huzinaga on outer electrons) was found sufficiently accurate to reproduce experimental data. Clusters containing up to seven Pd atoms were considered and their interaction with hydrogen, methane and ethane and their fragments was analyzed and a kinetic study of the system was performed. Transition states structures and energies were calculated through quantum mechanics and kinetic constants were derived from a statistic thermodynamic approach. On the basis of such information, a kinetic model that accounts for ethane transformations. Finally the kinetic scheme was embedded in a plug flow reactor model and simulations were performed to test the validity of the developed mechanism. In this way information obtained at the atomic scale were adopted to study phenomena occurring on the much higher reactor scale.

scholarly journals Variables Affecting NOx Formation in Lean-Premixed Combustion

1997 ◽  
Vol 119 (1) ◽  
pp. 102-107 ◽  
Author(s):  
R. C. Steele ◽  
A. C. Jarrett ◽  
P. C. Malte ◽  
J. H. Tonouchi ◽  
D. G. Nicol
Keyword(s):  
Residence Time ◽  
Combustion Temperature ◽  
Flow Reactor ◽  
Plug Flow ◽  
Volume Ratio ◽  
Chemical Reactor ◽  
Inlet Temperature ◽  
Reactor Model ◽  
Reactor Modeling ◽  
Lean Premixed

The formation of NOx in lean-premixed, high-intensity combustion is examined as a function of several of the relevant variables. The variables are the combustion temperature and pressure, fuel type, combustion zone residence time, mixture inlet temperature, reactor surface-to-volume ratio, and inlet jet size. The effects of these variables are examined by using jet-stirred reactors and chemical reactor modeling. The atmospheric pressure experiments have been completed and are fully reported. The results cover the combustion temperature range (measured) of 1500 to 1850 K, and include the following four fuels: methane, ethylene, propane, and carbon monoxide/hydrogen mixtures. The reactor residence time is varied from 1.7 to 7.4 ms, with most of the work done at 3.5 ms. The mixture inlet temperature is taken as 300 and 600 K, and two inlet jet sizes are used. Elevated pressure experiments are reported for pressures up to 7.1 atm for methane combustion at 4.0 ms with a mixture inlet temperature of 300 K. Experimental results are compared to chemical reactor modeling. This is accomplished by using a detailed chemical kinetic mechanism in a chemical reactor model, consisting of a perfectly stirred reactor (PSR) followed by a plug flow reactor (PFR). The methane results are also compared to several laboratory-scale and industrial-scale burners operated at simulated gas turbine engine conditions.

Modeling and Simulation Study of an Industrial Radial Moving Bed Reactor for Propane Dehydrogenation Process

2016 ◽  
Vol 14 (1) ◽  
pp. 33-44 ◽  
Author(s):  
Sim Yee Chin ◽  
Anwaruddin Hisyam ◽  
Haniif Prasetiawan
Keyword(s):  
Flow Reactor ◽  
Catalyst Activity ◽  
Coke Formation ◽  
Plug Flow ◽  
Propane Dehydrogenation ◽  
Propane Conversion ◽  
Reactor Model ◽  
Moving Bed ◽  
Coke Content ◽  
Experimental Values

AbstractAn accurate model is required to optimize the propane dehydrogenation reaction carried out in the radial moving bed reactors (RMBR). The present study modeled the RMBR using a plug flow reactor model incorporated with kinetic models expressed in simple power-law model. Catalyst activity and coke formation were also considered. The model was solved numerically by discretizing the RMBR in axial and radial directions. The optimized kinetic parameters were then used to predict the trends of propane conversion, temperature, catalyst activity and coke content in the RMBR along axial and radial directions. It was found that the predicted activation energies of the propane dehydrogenation, propane cracking and ethylene hydrogenation were in reasonable agreement with the experimental values reported in the literature. The model developed has accurately predicted the reaction temperature profile, conversion profile and catalyst coke content. The deviations of these simulated results from the plant data were less than 5%.

scholarly journals Variables Affecting NOx Formation in Lean-Premixed Combustion

1995 ◽  
Author(s):  
R. C. Steele ◽  
A. C. Jarrett ◽  
P. C. Malte ◽  
J. H. Tonouchi ◽  
D. G. Nicol
Keyword(s):  
Residence Time ◽  
Combustion Temperature ◽  
Flow Reactor ◽  
Plug Flow ◽  
Volume Ratio ◽  
Chemical Reactor ◽  
Inlet Temperature ◽  
Reactor Model ◽  
Reactor Modeling ◽  
Lean Premixed

The formation of NOx in lean-premixed, high-intensity combustion is examined as a function of several of the relevant variables. The variables are the combustion temperature and pressure, fuel-type, combustion zone residence time, mixture inlet temperature, reactor surface-to-volume ratio, and inlet jet size. The effects of these variables are examined by using jet-stirred reactors and chemical reactor modeling. The atmospheric pressure experiments have been completed and are fully reported. The results cover the combustion temperature range (measured) of 1500 to 1850K, and include the following four fuels: methane, ethylene, propane, and carbon monoxide/hydrogen mixtures. The reactor residence time is varied from 1.7 to 7.4ms, with most of the work done at 3.5ms. The mixture inlet temperature is taken as 300 and 600K, and two inlet jet sizes are used. Elevated pressure experiments are reported for pressures up to 7.1atm for methane combustion at 4.0ms with a mixture inlet temperature of 300K. Experimental results are compared to chemical reactor modeling. This is accomplished by using a detailed chemical kinetic mechanism in a chemical reactor model, consisting of a perfectly stirred reactor (PSR) followed by a plug flow reactor (PFR). The methane results are also compared to several laboratory-scale and industrial-scale burners operated at simulated gas turbine engine conditions.

Simulation and Validation of Hydrogen Production From Hydrogen Sulfide Pyrolysis

2016 ◽  
Author(s):  
J. Commenges ◽  
A. M. El-Melih ◽  
A. K. Gupta
Keyword(s):  
Experimental Data ◽  
Hydrogen Sulfide ◽  
New Technologies ◽  
Flow Reactor ◽  
Plug Flow ◽  
Treatment Method ◽  
Reactor Model ◽  
Thermal Pyrolysis ◽  
Production Of Hydrogen ◽  
Time Required

Pyrolysis of hydrogen sulfide has been studied for the treatment of hydrogen sulfide with simultaneous production of hydrogen and sulfur. This novel treatment method has been studied experimentally to provide fundamental information on the overall kinetic parameters. Numerical simulation of thermal pyrolysis of hydrogen sulfide is studied and the results obtained from the modified detailed chemical reaction mechanism are validated with the experimental data. The simulation results agreed favorably well with the experimental data for all examined temperatures up to 1473K. The thermal pyrolysis of hydrogen sulfide has been studied at residence times of 0.4 to 1.5 seconds and at temperatures of 1273–1473K. Experiments and simulations were also conducted using hydrogen sulfide diluted with 95% nitrogen using a heated quartz plug flow reactor to avoid any catalytic effects and excessive build of sulfur during experimentation. Numerically plug flow type reactor model was used to simulate the hydrogen sulfide thermal pyrolysis. The available mechanism in the literature provided poor match with the experimental data at temperatures higher than 1273 K. A modified mechanism is proposed and validated with our experimental data. Both simulations and experimental results showed increased conversion of H2S to hydrogen at increased temperatures. The increase in temperature reduced the residence time required to reach a steady asymptotic equilibrium value. Based on the qualitative agreement between simulations and experimental data under the investigated conditions, the reaction pathways as well as the most dominant reactions on hydrogen sulfide thermal pyrolysis are also presented. These results assist our efforts in the development of new technologies for hydrogen sulfide treatment.

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