Ignition of Lean Methane-Based Fuel Blends at Gas Turbine Pressures

2005 ◽  
Author(s):  
Eric L. Petersen ◽  
Joel M. Hall ◽  
Schuyler D. Smith ◽  
Jaap de Vries ◽  
Anthony Amadio ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Oxidation Kinetics ◽  
Rate Coefficients ◽  
Fuel Blends ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Lean Fuel ◽  
Fuel Mixtures ◽  
Kinetics Of ◽  
Good Agreement

Shock-tube experiments and chemical kinetics modeling were performed to further understand the ignition and oxidation kinetics of lean methane-based fuel blends at gas turbine pressures. Ignition delay times were obtained behind reflected shock waves for fuel mixtures consisting of CH4, CH4/H2, CH4/C2H6, and CH4/C3H8 in ratios ranging from 90/10 to 60/40%. Lean fuel/air equivalence ratios (φ = 0.5) were utilized, and the test pressures ranged from 0.54 to 25.3 atm. A methane-oxidation kinetics mechanism based on GRI-Mech 3.0 was assembled to reproduce the methane/air mixtures. Additional reactions involving CH3O and CH3O2 chemistry and modifications to a few of the pressure-dependent reaction rate coefficients were needed to achieve good agreement between data and model.

scholarly journals Experimental Study on High Pressure Combustion of Decomposed Ammonia: How Can Ammonia Be Best Used in a Gas Turbine?

2021 ◽  
Author(s):  
Mario Ditaranto ◽  
Inge Saanum ◽  
Jenny Larfeldt
Keyword(s):  
Experimental Study ◽  
High Pressure ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Favourable Effect ◽  
Small Scale ◽  
Nox Formation ◽  
Fuel Blends ◽  
Combustion Properties ◽  
Fuel Mixtures

Abstract Hydrogen, a carbon-free fuel, is a challenging gas to transport and store, but that can be solved by producing ammonia, a worldwide commonly distributed chemical. Ideally, ammonia should be used directly on site as a fuel, but it has many combustion shortcomings, with a very low reactivity and a high propensity to generate NOx. Alternatively, ammonia could be decomposed back to a mixture of hydrogen and nitrogen which has better combustion properties, but at the expense of an endothermal reaction. Between these two options, a trade off could be a partial decomposition where the end use fuel is a mixture of ammonia, hydrogen, and nitrogen. We present an experimental study aiming at finding optimal NH3-H2-N2 fuel blends to be used in gas turbines and provide manufacturers with guidelines for their use in retrofit and new combustion applications. The industrial burner considered in this study is a small-scale Siemens burner used in the SGT-750 gas turbine, tested in the SINTEF high pressure combustion facility. The overall behaviour of the burner in terms of stability and emissions is characterized as a function of fuel mixtures corresponding to partial and full decomposition of ammonia. It is found that when ammonia is present in the fuel, the NOx emissions although high can be limited if the primary flame zone is operated fuel rich. Increasing pressure has shown to have a strong and favourable effect on NOx formation. When ammonia is fully decomposed to 75% H2 and 25% N2, the opposite behaviour is observed. In conclusion, either low rate or full decomposition are found to be the better options.

scholarly journals Estudo cinético da abstração do hidrogênio do acetato de metila

2020 ◽  
Author(s):  
Leandro da Silva Pereira ◽  
Leonardo Baptista
Keyword(s):  
Transition State Theory ◽  
Methyl Esters ◽  
Hydrogen Abstraction ◽  
State Theory ◽  
Basis Set ◽  
Rate Coefficients ◽  
Dft Methods ◽  
Carbon Chains ◽  
Kinetics Of ◽  
Good Agreement

Biodiesel is a fuel formed by methyl esters with large carbon chains. The investigation of the hydrogen abstraction reactions of small methyl esters can be helpful to the improvement and development of kinetics models of biodiesel combustion. For this reason, the present study aims to study the thermochemistry and kinetics of hydrogen abstraction of methyl ethanoate using DFT methods and transition state theory. The abstraction reactions by O2, O, HO2, and H were studied with the B3LYP-D3 and M06-2X functionals with cc-pVDZ, ccpVTZ, aug-cc-pVDZ, and aug-cc-pVTZ basis set. At 298 K, the rate coefficients evaluated are in good agreement with the literature’s coefficients and the faster reaction occurs in the presence of O atoms. The hydrogen abstraction by O2 molecule it is not important at 298 K, but should be included in the present study since it should be important at higher temperatures.

Ignition Delay Time Measurements of C2HX Fuels and Comparison to Several Detailed Kinetics Mechanisms

2004 ◽  
Author(s):  
Eric L. Petersen ◽  
Joel M. Hall ◽  
Danielle M. Kalitan ◽  
Matthew J. A. Rickard
Keyword(s):  
Ignition Delay ◽  
Conclusive Evidence ◽  
Detailed Chemical Kinetics ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Electronically Excited ◽  
Detailed Kinetics ◽  
Detailed Chemical ◽  
Good Agreement

Recent results from experiments and modeling by the authors are reviewed for the ignition of acetylene, ethylene, and ethane in oxygen/argon mixtures at temperatures between 1000 and 2300 K and pressures near 1 atm. The ignition measurements were obtained behind reflected shock waves using emission from electronically excited OH and CH radicals to monitor the reaction progress. While many discrepancies exist amongst previous studies for these lower-order hydrocarbons, the accuracy afforded by the present experiments provides conclusive evidence verifying the trends seen in certain studies from the literature. Several modern, detailed chemical kinetics mechanisms were compared to the new results with some models showing quite good agreement with both ignition delay times and species profiles, particularly for stoichiometric mixtures. However, improvement is still required to match the entire range of fuel concentrations, temperatures, and mixture ratios, particularly for fuel-rich mixtures.

scholarly journals Theoretical calculations of the kinetics of the OH reaction with 2-methyl-2-propen-1-ol and its alkene analogue

RSC Advances ◽  
2014 ◽  
Vol 4 (40) ◽  
pp. 20830-20840 ◽  
Author(s):  
Thaís da Silva Barbosa ◽  
Jorge D. Nieto ◽  
Pablo M. Cometto ◽  
Silvia I. Lane ◽  
Glauco Favilla Bauerfeldt ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Calculations ◽  
Rate Coefficients ◽  
Kinetics Of ◽  
Good Agreement

The rate coefficients for the OH addition to 2-methyl-2-propen-1-ol and methylpropene have been determined, showing a non-Arrhenius profile and good agreement with the experimental data.

Oxidation kinetics of n-nonane: Measurements and modeling of ignition delay times and product concentrations

2011 ◽  
Vol 33 (1) ◽  
pp. 175-183 ◽  
Author(s):  
B. Rotavera ◽  
P. Diévart ◽  
C. Togbé ◽  
P. Dagaut ◽  
E.L. Petersen
Keyword(s):  
Oxidation Kinetics ◽  
Ignition Delay ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Kinetics Of

Ignition of Lean Methane-Based Fuel Blends at Gas Turbine Pressures

2007 ◽  
Vol 129 (4) ◽  
pp. 937-944 ◽  
Author(s):  
Eric L. Petersen ◽  
Joel M. Hall ◽  
Schuyler D. Smith ◽  
Jaap de Vries ◽  
Anthony R. Amadio ◽  
...  
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Gas Turbine ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Ignition Time ◽  
Fuel Blends ◽  
Reflected Shock

Shock-tube experiments and chemical kinetics modeling were performed to further understand the ignition and oxidation kinetics of lean methane-based fuel blends at gas turbine pressures. Such data are required because the likelihood of gas turbine engines operating on CH4-based fuel blends with significant (>10%) amounts of hydrogen, ethane, and other hydrocarbons is very high. Ignition delay times were obtained behind reflected shock waves for fuel mixtures consisting of CH4, CH4∕H2, CH4∕C2H6, and CH4∕C3H8 in ratios ranging from 90/10% to 60/40%. Lean fuel/air equivalence ratios (ϕ=0.5) were utilized, and the test pressures ranged from 0.54 to 30.0atm. The test temperatures were from 1090K to 2001K. Significant reductions in ignition delay time were seen with the fuel blends relative to the CH4-only mixtures at all conditions. However, the temperature dependence (i.e., activation energy) of the ignition times was little affected by the additives for the range of mixtures and temperatures of this study. In general, the activation energy of ignition for all mixtures except the CH4∕C3H8 one was smaller at temperatures below approximately1300K(∼27kcal∕mol) than at temperatures above this value (∼41kcal∕mol). A methane/hydrocarbon–oxidation chemical kinetics mechanism developed in a recent study was able to reproduce the high-pressure, fuel-lean data for the fuel/air mixtures. The results herein extend the ignition delay time database for lean methane blends to higher pressures (30atm) and lower temperatures (1100K) than considered previously and represent a major step toward understanding the oxidation chemistry of such mixtures at gas turbine pressures. Extrapolation of the results to gas turbine premixer conditions at temperatures less than 800K should be avoided however because the temperature dependence of the ignition time may change dramatically from that obtained herein.

Surface Oxidation Kinetics of an a-Si3 N4 and an Amorphous Si3 N4 Powder

1991 ◽  
Vol 249 ◽  
Author(s):  
Pu Sen Wang ◽  
S. G. Malghan ◽  
S. M. Hsu ◽  
T. N. Wittberg
Keyword(s):  
Photoelectron Spectroscopy ◽  
Oxidation Kinetics ◽  
Surface Oxidation ◽  
Amorphous Powder ◽  
Oxide Thickness ◽  
Heating Time ◽  
Kcal Mole ◽  
Linear Rate ◽  
Kinetics Of ◽  
Good Agreement

ABSTRACTSurface oxidation kinetics of an a-Si3 N4 submicron size and an amorphous nano-size powder have been studied using x-ray photoelectron spectroscopy (XPS) and Bremsstrahlung-excited Auger electron spectroscopy (AES). The samples were oxidized by heating in air at temperatures between 850°C and 1000°C. The oxide thickness for each heating time and temperature was determined both from the relative 0 Is and N Is XPS peak intensities and from the Si02 and Si3 N4 Si KLL peak intensities. In each case, there was a good agreement between the oxide thickness value calculated from the XPS data and that obtained from the AES data. At these temperatures, oxidation followed a linear rate law. Activation energies of 15±1 kcal/mole and 27±1 kcal/mole were measured for the a-powder and the amorphous powder, respectively.

Impact Of Synthesis Route on the Water Oxidation Kinetics of Hematite Photoanodes

2020 ◽  
Author(s):  
Camilo A. Mesa ◽  
Ludmilla Steier ◽  
Benjamin Moss ◽  
Laia Francàs ◽  
James E. Thorne ◽  
...  
Keyword(s):  
Oxygen Vacancy ◽  
Reaction Kinetics ◽  
Water Oxidation ◽  
Oxidation Kinetics ◽  
Oxidation Reaction ◽  
Charge Accumulation ◽  
Optical Signals ◽  
Current Voltage ◽  
Voltage Performance ◽  
Kinetics Of

<p><i>Operando</i> spectroelectrochemical analysis is used to determine the water oxidation reaction kinetics for hematite photoanodes prepared using four different synthetic procedures. Whilst these photoanodes exhibit very different current / voltage performance, their underlying water oxidation kinetics are found to be almost invariant. Lower photoanode performance was found to correlate with the observation of optical signals indicative of charge accumulation in mid-gap oxygen vacancy states, indicating these states do not contribute directly to water oxidation.</p>

Diffusion model for deposition of epitaxial GaAs layers prepared by the MOCVD method

1991 ◽  
Vol 56 (10) ◽  
pp. 2020-2029
Author(s):  
Jindřich Leitner ◽  
Petr Voňka ◽  
Josef Stejskal ◽  
Přemysl Klíma ◽  
Rudolf Hladina
Keyword(s):  
Experimental Data ◽  
Growth Rate ◽  
Kinetic Model ◽  
Gas Phase ◽  
Substrate Surface ◽  
Deposition Process ◽  
Hydrogen Atmosphere ◽  
Epitaxial Gaas ◽  
Kinetics Of ◽  
Good Agreement

The authors proposed and treated quantitatively a kinetic model for deposition of epitaxial GaAs layers prepared by reaction of trimethylgallium with arsine in hydrogen atmosphere. The transport of gallium to the surface of the substrate is considered as the controlling process. The influence of the rate of chemical reactions in the gas phase and on the substrate surface on the kinetics of the deposition process is neglected. The calculated dependence of the growth rate of the layers on the conditions of the deposition is in a good agreement with experimental data in the temperature range from 600 to 800°C.

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