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Artykuły w czasopismach na temat "Natural gas-oxidizer"
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Dzurňák, Róbert, Augustín Varga, Ján Kizek, Gustáv Jablonský i Ladislav Lukáč. "Influence of Burner Nozzle Parameters Analysis on the Aluminium Melting Process". Applied Sciences 9, nr 8 (18.04.2019): 1614. http://dx.doi.org/10.3390/app9081614.
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The paper presents the results of the optimisation of burner nozzle diameters during the combustion of natural gas under the conditions of increasing oxygen concentrations in the oxidizer in aluminium melting processes in drum rotary furnaces. The optimisation of outlet nozzle diameters was performed employing the method of experimental measurements, the results of which can be used for aluminium melting in hearth furnaces. The measurements were carried out using an experimental upstream burner with 13.5 kW input power. The monitored oxygen concentrations in the oxidizer ranged from 21% to 50%. The measurements were performed and evaluated in two variations of the burner configuration (geometry). In the first study, the impact of the enriched oxidizer on the melting of aluminium ingots was evaluated with the defined diameter of the air nozzle, which resulted in a reduction of the aluminium charge melting time by 50% at 45.16% oxygen concentration in the oxidizer, thus achieving savings in the consumption of fuel used for melting. In the second study, the diameter was optimised depending on the combustion rate of the natural gas and oxidizer mixture. The optimisation of the nozzle parameters resulted in the reduction of the charge melting time by 23.66%, while the same 25% enriched oxidizer was used. With the rise of the enrichment level to 35%, further reduction by approximately 12% was observed. The measurement results prove considerable influence of the parameter (geometry) optimisation of the outlet nozzles and oxidizer enrichment. Appropriately selected parameters of the burner can contribute to achieving comparable results at a lower enrichment of the oxidizer. The obtained results demonstrate the intensification of the heat transfer in the current thermal aggregates. The research conclusions confirm that oxygen-enhanced combustion and modification of existing burners reduces the specific energy consumption on the process and reduces CO2 emissions.
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Soroka, B. S., i V. V. Horupa. "ANALYSIS OF THE PROCESS OF WATER VAPOR CONDENSATION WITHIN GAS ATMOSPHERES AND COMBUSTION PRODUCTS". Energy Technologies & Resource Saving, nr 1 (20.03.2017): 3–18. http://dx.doi.org/10.33070/etars.1.2017.01.
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Water vapor is the most important working medium by the processes of energy generation and conversion. The H2O content in gases and gas mixtures serves as a standard of their desiccation by technological processes. The presence of vapor in the air-oxidizer provides a reduction of harmful substances formation by combustion. The values characterizing the saturation state: the dew point tdew and the wet bulb thermometer twb temperature are used to evaluate an approximation degree of the wet gas system (any air, gas mixtures or combustion products) to the condensation state. The values of these parameters have been determined for moist air in dependence on the basic temperature and the relative humidity of an air. The lower are the temperature values tdew, twb, the wider is the region of H2O existence in the vapor phase. The EUROSTAT’s gas fuels list includes the natural gas (NG), blast furnace gas (BFG), coke oven gas (COG). Calculations of dew point values of the combustion products for the gas fuels: NG, COG, BFG has been carried out in dependence on the characteristics of the combustion air: the oxidizer excess factor l, the temperature ta and the relative humidity ja. The dew point tdew values have been found under standard conditions for the combustion products of the listed gas fuels, presented by stoichiometric (l = 1.0) mixtures with dry air: pure methane, NG, COG, BFG. The tdew values make — respectively 59.3; 58.5; 11.1; 61.5. In the case of saturated air as an oxidizer at temperature of 25 °C, the dew point for the combustion products of the listed fuels makes the folloving values: 62.0; 61.5; 25.6; 64.0 °C respectively. The fractions of H2O in the vapor and liquid phases of natural gas combustion products are determined as a function of temperature by condition that the 100 % content of H2O in from of vapor state (without water) corresponds to the saturation temperature (or dew point).This temperature has value of about 60°C for combustion products under stoichiometric air/gas ratio. Bibl. 31, Fig. 10, Tab. 3.
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Ермолаев, Денис Васильевич, i Айрат Заудатович Даминов. "INFLUENCE OF THE OXIDIZER ON THE FORMATION AND PURIFICATION EFFICIENCY OF ACID GASES PRODUCED DURING ASPHALTENE GASIFICATION". Bulletin of the Tomsk Polytechnic University Geo Assets Engineering 333, nr 4 (20.04.2022): 215–23. http://dx.doi.org/10.18799/24131830/2022/4/3474.
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Link for citation: Ermolaev D.V., Daminov A.Z. Influence of the oxidizer on the formation and purification efficiency of acid gases produced during asphaltene gasification. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2022, vol. 333, no. 4, рр. 215-223. In Rus.
The relevance of the study is determined by the need to understand the influence of the oxidizer on the formation of acid gases (CO2, H2S, COS and CS2) during thermal decomposition of high-viscosity hydrocarbons. This is important for predicting the purification efficiency of the produced gasification products and estimating the economic costs. The aim: using the simulation to study the effect of an oxidizer in the form of steam on the composition and properties of asphaltene gasification products obtained from natural bitumen, as well as to determine the cleaning efficiency depending on the amount of steam and the absorbent based on NaOH water-alkaline solution. Object: asphaltene of natural bitumen of Ashalchinskoe field of the Tatarstan Republic (Russia), oxidizer in the form of steam, the value of which varied from 0,1 to 1 depending on the amount of asphaltene. Methods: simulation of asphaltene gasification and acid gas absorption taking into account influence of an oxidizer in a form of steam with regard for basic chemical kinetics, ultimate analysis and TGA. Simulation results of gasification and absorption showed that steam used as an oxidizer during asphaltene gasification has a significant influence on the composition and properties of gasification products, as well as on the purification of syngas. With the increase of steam, a parabolic dependence of the concentrations of syngas components is observed, which values decrease with time, except for CO2. The calorific value of syngas decreases from 11,3 to 7,2 MJ/m3 and the cold gas efficiency increases from 53,4 to 62,5 % due to growth of syngas yield. As the amount of steam increases, the amount of absorbent decreases and the purification efficiency of acid gases rises. Thus, the amount of absorbed CO2 increases by 20,7 % while the absorbent decreases by 6,7%. At the same time the amount of absorbed H2S increased by 0,39 % with decrease of NaOH by 40,9 %.
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Landfahrer, M., C. Schluckner, H. Gerhardter, T. Zmek, J. Klarner i C. Hochenauer. "Numerical model incorporating different oxidizer in a reheating furnace fired with natural gas". Fuel 268 (maj 2020): 117185. http://dx.doi.org/10.1016/j.fuel.2020.117185.
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Sigal, Aleksandr, i Dmitri Paderno. "EFFECT OF MOISTURE ON NITROGEN DIOXIDE FORMATION IN LAMINAR FLAME OF NATURAL GAS". Journal of Environmental Engineering and Landscape Management 29, nr 3 (15.09.2021): 287–97. http://dx.doi.org/10.3846/jeelm.2021.15492.
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The paper contains the results of experimental studies of the effect of moisture on nitrogen dioxide formation and on oxidation of NO to NO2 in laminar premixed flame of natural gas. The water vapor is shown to be the third very influential participant, along with fuel and oxidizer, in the combustion process. Injection of moisture into the combustion zone has an effect due to the insertion of additional quantities of HO2- and OH– radicals into the process, which contributes to the intensification of the oxidation of NO to NO2. Introduction of the concept of the “excess moisture ratio” in the combustion process is proposed. The studies were executed at the laboratory installation in conditions of formation of the V-shaped laminar flame of natural gas behind a transverse cylindrical steel stabilizer, with determining the concentrations of flue gas components.
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Soroka, B. S., i N. V. Vorobyov. "Efficiency of the Use of Humidified Gas Fuel and Oxidizing Mixture". ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations 62, nr 6 (29.11.2019): 547–64. http://dx.doi.org/10.21122/1029-7448-2019-62-6-547-564.
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The influence of hydration of the components of combustion (air-oxidizer and – in some cases – fuel) including hydration in the conditions of substitution of natural gas by alternative gas fuels, viz. by coke blast furnace mixture and natural blast furnace mixture – on energy efficiency of the use of different fuels has been determined. Calculations of fuel saving for substitution of natural gas (NG) by wet process gas (blast furnace gas (BFG), coke gas (CG), their mixtures) were performed taking into account real technological parameters (on the example of a specific metallurgical plant). All the calculations were performed within the framework of the author’s methodology on fuel substitution grounded on the 1st and the 2nd laws of thermodynamics. The analysis of possibility for saving or overspending NG is performed in the conditions of preservation of the flow of the used total enthalpy (as the main requirement of the methodology that had been proposed) and of taking into account the corresponding efficiency of fuel use. The calculation of the required heat flow of natural gas combustion depending on the content of wet blast furnace gas in NG + BFG mixtures for the cases of NG substitution by process gases has been carried out. It is established that the presence of moisture in the fuel-oxidation mixture always reduces the efficiency of the combustion chamber or the energy process and the unit. In order to increase the efficiency of a high-temperature furnace (boiler), it is necessary to provide heating of combustion components when utilizing the heat of the outgoing combustion products. It is shown that the efficiency of the fuel-using system can be significantly increased when the potential (excess total enthalpy) of the working fluid (combustion products) is activated. There are additiоnal benefits due to the fact that the existing heat of products of combustion with humid air in a full range of temperatures – from the theoretical combustion temperature to ambient temperature under conditions of equilibrium, including account of the heat of condensation – increases with increasing moisture content of the initial components of combustion, viz. air-oxidizer and/or fuel gas.
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Ahn, Joon, i Hyouck-Ju Kim. "Combustion Characteristics of 0.5 MW Class Oxy-Fuel FGR (Flue Gas Recirculation) Boiler for CO2 Capture". Energies 14, nr 14 (18.07.2021): 4333. http://dx.doi.org/10.3390/en14144333.
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A 0.5 MW class oxy-fuel boiler was developed to capture CO2 from exhaust gas. We adopted natural gas as the fuel for industrial boilers and identified characteristics different from those of pulverized coal, which has been studied for power plants. We also examined oxy-fuel combustion without flue gas recirculation (FGR), which is not commonly adopted in power plant boilers. Oxy-fuel combustion involves a stretched flame that uniformly heats the combustion chamber. In oxy-natural-gas FGR combustion, water vapor was included in the recirculated gas and the flame was stabilized when the oxygen concentration of the oxidizer was 32% or more. While flame delay was observed at a partial load for oxy-natural-gas FGR combustion, it was not observed for other combustion modes. In oxy-fuel combustion, the flow rate and flame fullness decrease but, except for the upstream region, the temperature near the wall is distributed not lower than that for air combustion because of the effect of gas radiation. For this combustion, while the heat flux is lower than other modes in the upstream region, it is more than 60% larger in the downstream region. When oxy-fuel and FGR combustion were employed in industrial boilers, more than 90% of CO2 was obtained, enabling capture, sequestration, and boiler performance while satisfying exhaust gas regulations.
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Serbin, Serhiy, Kateryna Burunsuz, Daifen Chen i Jerzy Kowalski. "Investigation of the Characteristics of a Low-Emission Gas Turbine Combustion Chamber Operating on a Mixture of Natural Gas and Hydrogen". Polish Maritime Research 29, nr 2 (1.06.2022): 64–76. http://dx.doi.org/10.2478/pomr-2022-0018.
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Abstract This article is devoted to the investigation of the characteristics of a low-emission gas turbine combustion chamber, which can be used in Floating Production, Storage and Offloading (FPSO) vessels and operates on a mixture of natural gas and hydrogen. A new approach is proposed for modelling the processes of burning out a mixture of natural gas with hydrogen under preliminary mixing conditions in gaseous fuel with an oxidizer in the channels of radial-axial swirlers of flame tubes. The proposed kinetic hydrocarbon combustion scheme is used in three-dimensional calculations for a cannular combustion chamber of a 25 MW gas turbine engine for two combustion models: the Finite-Rate/Eddy-Dissipation and the Eddy Dissipation Concept. It was found that, for the investigated combustion chamber, the range of stable operations, without the formation of a flashback zone in the channels of radial-axial swirlers, is determined by the hydrogen content in the mixture, which is less than 25-30% (by volume). For the operating modes of the chamber without the formation of a flashback zone inside the swirler channels, the emissions of nitrogen oxide NO and carbon monoxide CO do not exceed the values corresponding to modern environmental requirements for emissions of toxic components by gas turbine engines.
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Director, L. B., K. A. Homkin, I. L. Maikov, Yu L. Shekhter, G. F. Sokol i V. M. Zaichenko. "Theoretical and Experimental Investigations of Substantiating Technologies for Carbon Materials Production from Natural Gas". Eurasian Chemico-Technological Journal 5, nr 1 (12.07.2017): 29. http://dx.doi.org/10.18321/ectj587.
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The results of theoretical and experimental investigations on methane pyrolysis with infiltration through a heated porous matrix generated from various carbon materials are presented. The features of mathematical<br />models, kinetic relationships of process are discussed. The mathematical model of process shares on external problem (a flow of particles in an external stream) and internal problem (reaction in particle porous). The<br />heat and mass transfer for the average (over the reactor cross section) parameters, ignoring the heat transfer in gas by thermal conductivity, is described by unsteady-state one-dimensional differential equations in<br />partial derivatives. For the mathematical description of process kinetics of methane decomposition the approach is used by which the soot formation is treated as a chain radical process. The porous media is represented by a system of large enough particles. In its turn, every macroparticle consists of finer particles, which are also composed of microparticles, etc. Calculating programs were used for modeling and efficiency analysis of technological installations for technical carbon production in a regenerative heater, filled by a ceramic nozzle and for similar purposes concerning carbon (oven soot) in autothermal torch process of partial gas oxidation by air at a surplus factor of oxidizer in relation to stoichiometry 0.4-0.5 at pressure close to atmospheric on Sosnogorsk Gas-Processing Plant. Experiment descriptions and techniques for experimental realization are given. These results are used as fundamentals for new technologies considering pyrocarbon materials production in the continuous operation reactor.
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Mathieu, P., i R. Nihart. "Zero-Emission MATIANT Cycle". Journal of Engineering for Gas Turbines and Power 121, nr 1 (1.01.1999): 116–20. http://dx.doi.org/10.1115/1.2816297.
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In this paper, a novel technology based on the zero CO2 emission MATIANT (contraction of the names of the two designers MAThieu and IANTovski) cycle is presented. This latter is basically a gas cycle and consists of a supercritical CO2 Rankine-like cycle on top of regenerative CO2 Brayton cycle. CO2 is the working fluid and O2 is the fuel oxidizer in the combustion chambers. The cycle uses the highest temperatures and pressures compatible with the most advanced materials in the steam and gas turbines. In addition, a reheat and a staged compression with intercooling are used. Therefore, the optimized cycle efficiency rises up to around 45 percent when operating on natural gas. A big asset of the system is its ability to remove the CO2 produced in the combustion process in liquid state and at high pressure, making it ready for transportation, for reuse or for final storage. The assets of the cycle are mentioned. The technical issues for the predesign of a prototype plant are reviewed.
Rozprawy doktorskie na temat "Natural gas-oxidizer"
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Khan, Abdul Rahman. "Effect of higher hydrocarbon, encrichment with H2, and dilution with H2/CO2 on the laminar burning velocity and flame stability of natural gas-oxidizer mixtures". Thesis, IIT Delhi, 2019. http://eprint.iitd.ac.in:80//handle/2074/8128.
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Chiu, Chui-Ling, i 邱垂嶺. "Study on natural gas conservation of zeolite rotor concentrator and regenerative thermal oxidizer operation -an example of TFT-LCD industry". Thesis, 2013. http://ndltd.ncl.edu.tw/handle/xg2z68.
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碩士國立交通大學
工學院產業安全與防災學程
101
Abstract In thin film transistor liquid crystal display (TFT-LCD) manufacturing plants, the zeolite concentrator with an oxidation process worked by nature gas energy is one of the most popular methods to control volatile organic compounds exhaust that contains complicated components with high flow volume and low concentration. This study explores various energy saving zeolite concentrator and regenerative thermal oxidizer technologies to find out the optimized conditions for improving the energy conservation and reducing the cost under the current environmental regulations. The tested data of the “thermal energy recycle” adapted in this study indicate that the outlet temperature in the zeolite rotor concentrator desorption area has been effectively increased and the usage of nature gas has been decreased. The real fabrication plant test data show that a single zeolite concentrate rotor incineration system would reduce the total nature gas consumption by 181,332 m3 per year, cost saving of around NT 3,401,788 per year , and the CO2 emission reduction of 340,904 Kg per year. The data also suggest that the adjustment of the “hot gas bypass damper opening ” contributes to 51.2% of natural gas conservation which is the most significant adjustment parameters. Other adjustments of “desorption air flow”, “ratation speed”, “thermal energy recycle”, “desorption (regenration) temperature”, and “furnace temperature” account for the natural gas conservation rates of 20.3%, 9.7%, 6.8%, 6.3%, and 5.8%, respectively.
Streszczenia konferencji na temat "Natural gas-oxidizer"
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Woolderink, M. H. F., i J. B. W. Kok. "Ultra Rich Combustion of Natural Gas to Syngas". W ASME 2011 Turbo Expo: Turbine Technical Conference and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/gt2011-46383.
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In this paper the turbulent rich combustion process of perfectly premixed natural gas and oxidizer to syngas is investigated. Also an overview is given of an ultra rich combustion setup that is present at the Laboratory of Thermal Engineering of the University of Twente. The numerical investigation of the process is carried out as follows. The gaseous chemistry is described by a reaction progress variable based combustion model with detailed chemistry. The soot formation is described by the processes of nucleation, surface growth, agglomeration and oxidation. Also radiative heat loss of the gases and the soot particles is taken into account. The numerical model predicts the flow field, gaseous species, temperature, heat loss and soot mass fraction and number of soot particles. The combination of radiation and soot formation models with the combustion model will give a complete picture of the processes in the partial oxidation reactor. The numerical results will be validated with measurements on a reactor operating at pressures from 1 to 6 bar and at equivalence ratios 2 to 4. The measurements are to be done by taking samples from the reactor which are subsequently analyzed with a gas chromatograph and a Scanning Mobility Particle Sizer. The planned experiments will give valuable validation data for the performance of combustion and soot formation models at ultra rich conditions that are not yet available in literature.
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Park, Suhyeon, Gihun Kim, Anthony C. Terracciano i Subith Vasu. "High-Pressure Ignition and Flame Propagation Measurements of CO2 Diluted Natural Gas/Oxidizer Mixtures for Advanced Rocket and Gas Turbine Combustors". W AIAA Scitech 2020 Forum. Reston, Virginia: American Institute of Aeronautics and Astronautics, 2020. http://dx.doi.org/10.2514/6.2020-0128.
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Mohr, Jeffrey, Bret Windom, Daniel B. Olsen i Anthony J. Marchese. "Homogeneous Ignition Delay, Flame Propagation Rate and End-Gas Autoignition Fraction Measurements of Natural Gas and Exhaust Gas Recirculation Blends in a Rapid Compression Machine". W ASME 2020 Internal Combustion Engine Division Fall Technical Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icef2020-2998.
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Abstract To evaluate the effect of exhaust gas recirculation (EGR) and variable fuel reactivity on knock and misfire in spark ignited national gas engines, experiments were conducted in a rapid compression machine to measure homogeneous ignition delay, flame propagation rate, and end-gas autoignition fraction for stoichiometric natural gas/oxidizer/EGR blends. Natural gas with a range of chemical reactivity was simulated using mixtures of CH4, C2H6, and C3H8. Reactive exhaust gas recirculation (R-EGR) gases were simulated with mixtures of Ar, CO2, CO, and NO and non-reactive exhaust gas recirculation gases (NR-EGR) were simulated with mixtures of AR and CO2. Homogeneous ignition delay period, flame propagation rate and end-gas autoignition fraction were measured at compressed pressures and temperatures of 30.2 to 34.0 bar and 667 to 980 K, respectively. Flame propagation rate decreased with both R-EGR and NR-EGR substitution. The substitution of R-EGR increased the end-gas autoignition fraction, whereas NR-EGR substitution decreased the end-gas autoignition fraction. The results indicate that the presence of the reactive species NO in the R-EGR has a strong impact on end-gas autoignition fraction. An 82-species reduced chemical kinetic mechanism was also developed that reproduces measured homogeneous ignition delay period with a total average relative error of 11.0%.
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Zhang, Na. "Comparative Study of Two Low CO2 Emission Cycle Options With Natural Gas Reforming". W ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27232.
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Two power plant schemes with natural gas reforming and CO2 emission reduction were analyzed and discussed. The first one integrates natural gas reforming technology with an oxy-fuel combined power cycle (OXYF-REF), with water as the main work fluid. The reforming heat is obtained from the available turbine exhaust heat, and the produced syngas is used as fuel with oxygen as the oxidizer. The turbine working fluid can expand down to a vacuum, producing a high pressure ratio. The second system adopts pre-combustion decarbonization and a chemical absorption technology for CO2 removal (PCD-REF). The gas turbine is the conventional air based one with compressor intercooling. Supplementary combustion is adopted to elevate the turbine exhaust temperature and thus achieve a much higher methane conversion rate (∼95%). Both cycles involve internal heat recuperation from gas turbine exhausts, and particular attention has been put on the integration of heat recovery chain to reduce the related exergy destruction. The systems are simulated and compared in terms of both thermal efficiency and CO2 removal. The OXYF-REF cycle has shown better performance with higher levels of CO2 removal and energy efficiency of 52%. The PCD-REF cycle showed a thermal efficiency of 43% and CO2 specific emission of 55.5 g/kWh.
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Saha, Pankaj, Pete Strakey i Donald Ferguson. "Numerical Investigations of Instabilities in a Natural Gas-Air Fueled Rotating Detonation Engine". W ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-91643.
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Abstract Recent numerical and experimental studies of Rotating Detonation Engines (RDEs) using air as the oxidizer have primarily focused on the ability to sustain a stable continuous detonation wave when fueled with hydrogen. For RDEs to be a viable technology for land-based power generation it is necessary to explore the ability to detonate natural gas and/or coal-syngas with air in the confines of the annular geometry of an RDE. There are major challenges in obtaining a stable detonation wave for a natural gas–air fueled RDE and to a lesser extent for coal-syngas and air. Recently published computational studies have, however, successfully simulated the underlying flow physics of detonative combustion for two-dimensional (2D) unrolled RDE geometries. In the present work, detonation wave characteristics of a hydrogen-natural gas fueled RDE have been numerically investigated and analyzed to understand the stability of natural gas detonations and detonability limits of fuel blends at relatively low operating combustor pressure. A series of detonation sensitivity studies have been conducted by varying the natural gas content in a hydrogen-natural gas fuel mixture, to assess the stability limit of natural gas detonations in an air breathing RDE. The current study explores the maximum percentage of natural gas content in a hydrogen-natural gas fuel blend that produces self-sustained, stable detonation waves. The simulations have been performed in a 2D unwrapped RDE geometry using the open-source CFD library OpenFOAM employing an unsteady pressure-based compressible reactive flow solver with a k–ε turbulence model in a structured rectangular grid system. Both reduced and detailed chemical kinetic models have been used to assess the effect of the chemistry on the detonation wave characteristics and underlying flow features. A systematic grid sensitivity study has been conducted with various grid sizes to quantify the weakly stable overdriven detonation on a coarse mesh and oscillating features at fine mesh resolutions. The low and high frequency instabilities have been analyzed from the time dependent pressure and temperature collected at various fixed spatial locations within the detonation height region. The results show that the peak pressure oscillates at low frequencies while for the high frequency instabilities, the peak pressure oscillates irregularly. Furthermore, at higher methane content, the high frequency instability leads to detonation extinction due to decoupling of the flame-front from the shock front. Wave speeds, peak pressures and temperatures, and dominant frequencies have been computed from the time histories. 2D contour maps of temperature and species concentrations have been used to visualize the flow structures, and calculate detonation height. Global wave speed and detonation height variations for varying methane content indicate the pathway to detonation failure at higher methane content for the current low pressure RDE. Experimental data from an air-breathing RDE fueled by natural gas-hydrogen fuel blends conducted in a detonation research laboratory at NETL, has been incorporated to verify the numerical findings.
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Saha, Pankaj, Peter Strakey, Donald Ferguson i Arnab Roy. "Numerical Analysis of Detonability Assessment in a Natural Gas-Air Fueled Rotating Detonation Engine". W ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-11728.
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Abstract Rotating Detonation Engines (RDE) offer an alternative combustion strategy to replace conventional constant pressure combustion with a process that could produce a pressure gain without the use of a mechanical compressor. Recent numerical and experimental publications that consider air as the oxidizer have primarily focused on the ability of these annular combustors to sustain a stable continuous detonation wave when fueled by hydrogen. However, for this to be a viable consideration for the land-based power generation it is necessary to explore the ability to detonate natural gas and air within the confines of the annular geometry of an RDE. Previous studies on confined detonations have expressed the importance of permitting detonation cells to fully form within the combustor in order to achieve stability. This poses a challenge for natural gas–air fueled processes as their detonation cell size can be quite large even at moderate pressures. Despite the practical importance, only a few studies are available on natural gas detonations for air-breathing RDE applications. Moreover, the extreme thermodynamic condition (high temperature inside the combustor) allows limited accessibility inside the combustor for detailed experimental instrumentations, providing mostly single-point data. Recent experimental studies at the National Energy Technology Laboratory (NETL) have reported detonation failure at higher methane concentration in an air-breathing RDE fueled by natural gas-hydrogen fuel blends. This encourages to perform a detailed numerical investigation on the wave characteristics of detonation in a natural gas-air fueled RDE to understand the various aspects of instability associated with the natural gas-air detonation. This study is a numerical consideration of a methane-air fueled RDE with varying operating conditions to ascertain the ability to achieve a stable, continuous detonation wave. The simulations have been performed in a 2D unwrapped RDE geometry using the open-source CFD library “OpenFOAM” employing an unsteady pressure-based compressible reactive flow solver with a k–ε turbulence model in a structured rectangular grid system. Both reduced and detailed chemical kinetic models have been used to assess the effect of the chemistry on the detonation wave characteristics and the underlying flow features. A systematic grid sensitivity study has been conducted with various grid sizes to quantify the weakly stable overdriven detonation on a coarse mesh and oscillating features at fine mesh resolutions. The main focus of the current study is to investigate the effects of operating injection pressure on detonation wave characteristics of an air-breathing Rotating Detonation Engine (RDE) fueled with natural gas-hydrogen fuel blends. Wave speeds, peak pressures and temperatures, and dominant frequencies have been computed from the time histories. The flow structures were then visualized using 2D contours of temperature and species concentration.
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Mathieu, Ph, i R. Nihart. "Zero Emission MATIANT Cycle". W ASME 1998 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/98-gt-383.
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In this paper, a novel technology based on the zero CO2 emission MATIANT (contraction of the names of the 2 designers: MATHIEU and IANTOVSKI) cycle is presented. This latter is basically a gas cycle and consists of a supercritical CO2 Rankine-like cycle on top of regenerative CO2 Brayton cycle. CO2 is the working fluid and O2 is the fuel oxidizer in the combustion chambers. The cycle uses the highest temperatures and pressures compatible with the most advanced materials in the steam and gas turbines. In addition, a reheat and a staged compression with intercooling are used. Therefore the optimized cycle efficiency rises up to around 45% when operating on natural gas. A big asset of the system is its ability to remove the CO2 produced in the combustion process in liquid state and at high pressure, making it ready for transportation, for reuse or for final storage. The assets of the cycle are mentioned. The technical issues for the predesign of a prototype plant are reviewed.
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Rahman, Ramees K., Samuel Barak, K. R. V. (Raghu) Manikantachari, Erik Ninnemann, Ashvin Hosangadi, Andrea Zambon i Subith S. Vasu. "Capturing the Effects of NOx and SOx Impurities on Oxy-Combustion Under Supercritical CO2 Conditions for Coal-Derived Syngas and Natural Gas Mixtures". W ASME Turbo Expo 2020: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/gt2020-14337.
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Abstract Direct fired supercritical carbon dioxide cycles are one of the most promising power generation method in terms of their efficiency and environmental friendliness. Two most important challenges in implementing these cycles are the high pressure (300 bar) and high CO2 dilution (>80 %) in the combustor. The design and development of supercritical oxy-combustors for natural gas requires accurate reaction kinetic models to predict the combustion outcomes. The presence of small amount of impurities in natural gas and other feed streams to oxy-combustors makes these predictions even more complex. During oxy-combustion, trace amounts of nitrogen present in the oxidizer is converted to NOx and gets into the combustion chamber along with the recirculated CO2. Similarly, natural gas can contain trace amount of ammonia and sulfurous impurities which gets converted to NOx and SOx and gets back into the combustion chamber with recirculated CO2. In this work, a reaction model is developed for predicting the effect of impurities like NOx and SOx on supercritical methane combustion. The base mechanism used in this work is GRI 3.0. H2S combustion chemistry is obtained from Bongartz et al. while NOx chemistry is from Konnov et al. The reaction model is then optimized for a pressure range of 30–300 bar using high pressure shock tube data from literature. It is then validated with data obtained from literature for methane combustion, H2S oxidation and NOx effects on ignition delay. The effect of impurities on CH4 combustion up to 16 atm is validated using NOx doped methane studies obtained from literature. In order to validate the model for high pressure conditions, experiments are conducted in a high pressure (∼100 bar) shock tube facility at UCF for natural gas identical mixtures with N2O as impurity. Current results show that there is significant change in ignition delay with the presence of impurities. A comparison is made with experimental data using the developed model and predictions are found to be in good agreement. The model developed was used to study the effect of impurities on CO formation from sCO2 combustor. It was found that NOx helps in reducing CO formation while presence of H2S results in formation of more CO. The reaction mechanism developed herein can also be used as a base mechanism to develop reduced mechanism for use in CFD simulations.
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Sundkvist, Sven Gunnar, Adrian Dahlquist, Jacek Janczewski, Mats Sjödin, Marie Bysveen, Mario Ditaranto, Øyvind Langørgen, Morten Seljeskog i Martin Siljan. "Concept for a Combustion System in Oxyfuel Gas Turbine Combined Cycles". W ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-94180.
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A promising candidate for CO2 neutral power production is Semi-Closed Oxyfuel Combustion Combined Cycles (SCOC CC). Two alternative SCOC-CCs have been investigated both with recirculation of the Working Fluid (CO2 and H2O) but with different H2O content due to different conditions for condensation of water from the Working Fluid. The alternative with low moisture content in the re-circulated Working Fluid has shown highest thermodynamic potential and has been selected for further study. The necessity to use recirculated exhaust gas as the Working Fluid will make the design of the gas turbine quite different from a conventional gas turbine. For a combined cycle using a steam Rankine cycle as a bottoming cycle it is vital that the temperature of the exhaust gas from the Brayton cycle is well suited for steam generation that fits steam turbine live steam conditions. For oxyfuel gas turbines with a combustor outlet temperature of the same magnitude as conventional gas turbines a much higher pressure ratio is required (close to twice the ratio as for a conventional gas turbine) in order to achieve a turbine outlet temperature suitable for combined cycle. Based on input from the optimized cycle calculations a conceptual combustion system has been developed, where three different combustor feed streams can be controlled independently: the natural gas fuel, the oxidizer consisting mainly of oxygen plus some impurities, and the re-circulated Working Fluid. This gives more flexibility compared to air-based gas turbines, but introduces also some design challenges. A key issue is how to maintain high combustion efficiency over the entire load range using as little oxidizer as possible and with emissions (NOx, CO, UHC) within given constraints. Other important challenges are related to combustion stability, heat transfer and cooling, and material integrity, all of which are much affected when going from air-based to oxygen-based gas turbine combustion. Matching with existing air-based burner and combustor designs has been done in order to use as much as possible of what is proven technology today. The selected stabilization concept, heat transfer evaluation, burner and combustion chamber layout will be described. As a next step the pilot burner will be tested both at atmospheric and high pressure conditions.
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Nicodemus, Julia Haltiwanger, Morgan McGuinness i Rijan Maharjan. "A Thermodynamic and Cost Analysis of Solar Syngas From the Zinc/Zinc-Oxide Cycle". W ASME 2014 8th International Conference on Energy Sustainability collocated with the ASME 2014 12th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/es2014-6389.
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We present a thermodynamic and cost analysis of synthesis gas (syngas) production by the Zn/ZnO solar thermochemical fuel production cycle. A mass, energy and entropy balance over each step of the Zn/ZnO syngas production cycle is presented. The production of CO and H2 is considered simultaneously across the range of possible stoichiometric combinations and the effects of irreversibilities due to both recombination in the quenching process following dissociation of ZnO and incomplete conversion in the fuel production step are explored. In the cost analysis, continuous functions for each cost component are presented, allowing estimated costs of syngas fuel produced at plants between 50 and 500MWth. For a solar concentration ratio of 10000, a dissociation temperature of 2300K, and a CO fraction in the syngas of 1/3, the maximum cycle efficiency is 39% for an ideal case in which there is no recombination in the quencher, complete conversion in the oxidizer, and maximum heat recovery. In a 100MWth plant, the cost to produce syngas would be $0.025/MJ for this ideal case. The effect of heat recuperation, recombination in the quencher, and incomplete conversion on efficiency and cost are explored. The effect of plant size and feedstock costs on the cost of solar syngas are also explored. The results underscore the importance improving quencher and oxidizer processes to reduce costs. However, even assuming the ideal case, the predicted cost of solar syngas is 5.5 times more expensive than natural gas on an energy basis. The process will therefore require incentive policies that support early implementation in order to become economically competitive.
Raporty organizacyjne na temat "Natural gas-oxidizer"
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Bajwa, Abdullah, i Timothy Jacobs. PR-457-17201-R02 Residual Gas Fraction Estimation Based on Measured Engine Parameters. Chantilly, Virginia: Pipeline Research Council International, Inc. (PRCI), luty 2019. http://dx.doi.org/10.55274/r0011558.
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Gas exchange processes in two-stroke internal combustion engines, commonly referred to as scavenging, are responsible for removing the exhaust gases in the combustion chamber and preparing the combustible fuel-oxidizer mixture that undergoes combustion and converts the chemical energy of the fuel into mechanical work. Scavenging is a complicated phenomenon because of the simultaneous introduction of fresh gases into the engine cylinder through the intake ports, and the expulsion of combustion products from the previous cycles through the exhaust ports. A non-negligible fraction of the gaseous mixture that is trapped in the cylinder at the conclusion of scavenging is composed of residual gases from the previous cycle. This can cause significant changes to the combustion characteristics of the mixture by changing its composition and temperature, i.e. its thermodynamic state. Thus, it is vital to have accurate knowledge of the thermodynamic state of the post-scavenging mixture to be able to reliably predict and control engine performance, efficiency and emissions. Two tools for estimating the trapped mixture state - a simple scavenging model and empirical correlations - were developed in this study. Unfortunately, it is not practical to directly measure the trapped residual fraction for engines operating in the field. To overcome this handicap, simple scavenging models or correlations, which estimate this fraction based on some economically measurable engine parameters, can be developed. This report summarizes the results of event-II of a multi-event project that aims to develop such mathematical formulations for stationary two-stroke natural gas engines using data from more advanced models and experimentation. In this event, results from a GT-Power based model for an Ajax E-565 single-cylinder engine are used to develop a three-event single zone scavenging model and empirical correlations. Both of these mathematical devices produce accurate estimates of the trapped mixture state. The estimates are compared to GT-Power results. In the next event of the project, these results will be validated using experimental data. Various steps followed in the development of the model have been discussed in this report, and at the end some results and recommendations for the next event of the project have been presented.