Addition Of Inert Gas Research Articles

A Two‐Compartment Fluidized Bed Reactor for CO2 Capture by Chemical‐Looping Combustion

AbstractChemical‐looping combustion (CLC) is a combustion method for a gaseous fuel with inherent separation of the greenhouse gas carbon dioxide. A CLC system consists of two reactors, an air reactor and a fuel reactor, and an oxygen carrier circulating between the two reactors. The oxygen carrier transfers the oxygen from the air to the fuel. The flue gas from the fuel reactor consists of carbon dioxide and water, while the flue gas from the air reactor is nitrogen from the air. A two‐compartment fluidized bed CLC system was designed and tested using a flow model in order to find critical design parameters. Gas velocities and slot design were varied, and the solids circulation rate and gas leakage between the reactors were measured. The solids circulation rate was found to be sufficient. The gas leakage was somewhat high but could be reduced by altering the slot design. Finally, a hot laboratory CLC system is presented with an advanced design for the slot and also with the possibility for inert gas addition into the downcomer for solids flow increase.

Characteristics of a novel method, inert gas step addition, for the investigation of gas-phase mass-transfer effects in a molten carbonate fuel cell

This work illuminated characteristics of the inert gas step addition (ISA) method with various time ranges of reactant-flow shift in a 100 cm2 class molten carbonate fuel cell. The flow shift caused by the volume between the addition port for the inert gas and the cell was controlled by the length of 0.6 cm tubes in a range from 0.8 to 4.8 m at the anode as well as the cathode. Anodic voltage peaks provoked by the inert gas addition depended on the tube length and became blunt at longer tube lengths, indicating that the anodic overpotential is a function of reactant flow rate. The anodic overpotential estimated by the ISA depended on the tube length, but it became a constant at longer tubes. The cathode showed a flat peak at the moment of inert gas addition regardless of the tube length, indicating that the cathode has a relatively small gas-phase mass-transfer resistance. The cathodic overpotential with ISA showed an insignificant dependence on tube length.

Characteristics of a novel method, inert gas step addition, for the investigation of gas-phase mass-transfer effects in a molten carbonate fuel cell

This work illuminated characteristics of the inert gas step addition (ISA) method with various time ranges of reactant-flow shift in a 100 cm 2 class molten carbonate fuel cell. The flow shift caused by the volume between the addition port for the inert gas and the cell was controlled by the length of 0.6 cm tubes in a range from 0.8 to 4.8 m at the anode as well as the cathode. Anodic voltage peaks provoked by the inert gas addition depended on the tube length and became blunt at longer tube lengths, indicating that the anodic overpotential is a function of reactant flow rate. The anodic overpotential estimated by the ISA depended on the tube length, but it became a constant at longer tubes. The cathode showed a flat peak at the moment of inert gas addition regardless of the tube length, indicating that the cathode has a relatively small gas-phase mass-transfer resistance. The cathodic overpotential with ISA showed an insignificant dependence on tube length.

Tuning the electron temperature of a nitrogen plasma by adding helium and argon

Using the global model and its concomitant profile shape factor and recent experimental ionization cross section, calculation of the electron temperature, Te, is carried out as a function of the mixing ratio in two-species N2/Ar and N2/He plasmas. The result is compared with measured values determined by the line-ratio technique in an inductively coupled plasma. The overall trend of the variation of the measured electron temperature is well described by the model: they agree in the N2/He plasma and the calculated Te becomes increasingly lower at higher argon partial pressure, up to ∼20% for a pure argon plasma. A second method uses an empirically determined profile shape factor for a pure nitrogen plasma and calculates the change of electron temperature due to the addition of inert gas. Except for the pure helium case, the difference between the measured and calculated value is <10% in the entire range of mixing ratio.

Knock prevention of CHP engines by addition of N 2 and CO 2 to the natural gas fuel

This work focuses on the prevention of knock in the case of spark ignition (SI) engines supplied by natural gas network. The effects of the addition of two inert gases (N 2 and CO 2) are experimentally studied. The added volumetric quantities are between 0% and 25% for N 2 and between 0% and 15% for CO 2. The thermal efficiency and the emissions of the engine are very slightly affected by the addition, whereas a significant increase of the knock limited spark timing (KLST) is always measured. A twice-higher augmentation of KLST is noted when CO 2 is added compared to N 2 for an equivalent volumetric concentration. The overall augmentation varies between +1 and +6 °CA depending on engine operation. Finally, a law for predicting the KLST augmentation implied by the addition of inert gases is deduced from all the measurements.

Reaction Model for Carbon, Manganese, and Oxygen in Bottom Blowing with Mixed Gas in Final Stage of Steel Refining in Converter

A theoretical study of the reaction rates of carbon, manganese, and oxygen was made, and the computational results were compared with experimental results from a commercial plant to enable prediction of the enhancement of the decarburization rate in the final stage of refining by bottom blowing with mixed gas. A reaction model which combines the stoichiometric and equilibrium relationships among carbon, manganese, and oxygen and their mass transfer rates was made for decarburization as a gas-metal reaction and for manganese and iron oxidation as slag-metal reactions. It was assumed that 1) addition of inert gas through submerged tuyeres contributes to bath stirring as well as to a decrease in CO pressure, and 2) all rate determining steps in the gas-metal and slag-metal reactions are the mass transfer of carbon, manganese, or oxygen in the molten steel. Fitting the parameters under a 1/1 oxygen-nitrogen flow rate ratio, the calculated metallurgical properties in ordinary blowing (bottom blowing with pure oxygen) agreed well with the experimental results. Calculations for certain operating factors showed that the decarburization rate increases and the oxidation rates of manganese and iron decrease as the bath temperature increases and the ratio of oxygen to inert gas decreases. The contribution ratio of the gas-metal reaction relative to the slag-metal reaction in bottom blowing with mixed gas is 6 to 9 times larger than that in top blowing with mixed gas.

204 廃棄物処理過程における火災事故のリスク評価とそれらを想定した着火抑制の研究

Recently, it has been increasing exhausted waste abundance and the quality is also become diversing. Along with the diverse of composition of waste, the case that flammable substance is mized in the disposal process has been increasing and the burst and blaze hazard are also on the rise. In this study, it proposed the cause investigation of an accident increase and the accident prevention measures by using the risk analysis. It aims to investigate the ignition controlling effect by the ignition characteristic of the combustible gas that assumed in the pyrolizer in the carrier of the garbage truck and in the ripper in addition and the inert gas addition, and to obtain the indicator of the overall explosion-proof measures from these experiment results and the analyses.

Investigation of impinging diffusion flames with inert gas

Experimental investigations on impinging diffusion flames mixing with inert gas were conducted. The combustion results and temperature measurements show that the non-reactive gas might dilute the local fuel concentration in the diffusion process. The shape of the column flame was symmetrical due to the flame stretch force. The results showed that a conical flame was changed by the addition of inert gas to the pure methane fuel. The weakening of the stretch boundary enhanced the mixing rate between the fuel and oxidizer, which would improve the fluctuation phenomenon. The impinging flame became shorter and bluer so the combustor size can be reduced. Nitrogen gas has the advantage that we can visualize the impinging mechanism with different gases in the impinging flame. The color in the mixing plane becomes blue and transparent. The penetration length is about 8 mm near the impinging point for Re=145.

Flame stretch analysis in diffusion flames with inert gas

Experimental investigations of impinging flame with fuel mixed with non-reaction gas were conducted. According to the observations of combustion test and temperature measurement, the non-reaction gas might dilute the local concentration of fuel in the diffusion process. The shape of the flame was symmetrical due to the flame stretch force. Results show that the conical flame might be de-structured by the addition of inert gas in pure methane fuel. The impinging flame became shorter and bluer as nitrogen was added to the fuel. The conditions of N2/CH4 equal to 1/2 and 1/1 show a wider plane in the YZ plane. The effect of inert gas overcomes the flame stretch and destroys the symmetrical column flame as well as the cold flow. Nitrogen addition also enhances the diffusion rate and combustion efficiency.

Plasma Diagnostics and the Evolution of a Novel Titanium Nitride Deposition Process

ABSTRACTMeasurement of the ion energy distributions (IED's) of N2+ ions produced in an inductively coupled plasma (ICP) source revealed that adding argon to the nitrogen gas before excitation in the source increased the nitrogen ion current. Adding helium resulted in an increase of the most probable ion energy, and a higher-energy component of the N2+ IED at about 20 eV. Preliminary calculations of the electron energy distributions (EED's) correlate well to the IED's for both inert gas additions. Experiments were performed to determine the effect of these modified energy distributions of the reactive species on titanium nitride thin film growth rates, microstructure and mechanical properties. Deposition experiments were conducted using the ICP source and an unbalanced magnetron with a titanium cathode. Results showed that the argon inert gas addition resulted in increased deposition rate and reduced 3-D features. Film roughness was decreased to 1.61 nm from 2.05 nm when helium was mixed with the nitrogen. Mixing both argon and helium with the nitrogen yielded combined effects of deposition rate increase, reduced 3-D features and increased smoothness. The inert gas additions increased hardness of the TiN films from 17.3 GPa to 21.1 GPa with the argon addition and to 25.0 GPa with the helium addition

Epitaxial growth of GaN using reactive neutrals extracted from the nitrogen Helicon wave plasma

A GaN epilayer on sapphire (0001) was grown using the N2 Helicon wave plasma assisted evaporation deposition process. Various methods to reduce the N2 ion impingement energy were attempted. The addition of inert gas (Ar, Ne) into the N2 plasma decreased the impingement of N2 ions and generated a higher quantity of activated nitrogen. In addition, the installation of mirror-type magnets effectively reduced the ion impingement energy. Although the ion impingement energy was less than the threshold (∼25 eV) for damaging GaN, the high flux of ion impingement during the growth of GaN induced a considerable strain in the epilayer. GaN film synthesized under direct ion impingement onto the growing surface has poor luminescent properties, despite its relatively good crystallinity. When the neutral nitrogen was utilized for GaN epilayer growth, the crystallinity and luminescent properties were greatly improved. Furthermore, with the decreasing of kinetic energy of fast neutral nitrogen, the in-plane crystallinity of GaN was improved and thus, an enhancement of luminescent properties was attained.

The Effects of Non-Air Mixtures on the Operation of a Diesel Engine by Experiment and by Simulation

This paper presents the findings of a detailed investigation to determine the performance effects of a diesel engine when the inert nitrogen (N 2 ) in air is replaced by carbon dioxide (CO 2 ). The requirement for a diesel engine to operate in such a manner is access to free air being prohibited, as is the case with a submarine power generation unit. Numerous projects have investigated non-air-breathing diesel engine systems. The more recent ones have concentrated on strategies whereby the recirculated non-air mixture maintains the thermodynamic properties of free air such that engine performance is not compromised. This has led to the addition of argon and other inert gases. However, systems utilizing purely fuel, oxygen and carbon dioxide mixtures have not been investigated since the 1960s, and owing to the confidentiality of defence-related work little public data have been made available. A Perkins T4.236 truck engine has been configured to operate on a mixture of 70 mol % CO 2 and 30 mol % O 2 when preheated to a temperature of 150 °C. Performance results show that under such inlet conditions the rated brake power of the engine (as defined by fuelling rate) degrades by 20-23 per cent with a subsequent increase in brake specific fuel consumption of 23-28 per cent. In-cylinder observations in relation to ignition delay and exhaust oxygen concentrations lead to the hypothesis that the carbon dioxide is seriously affecting both pre- and post-ignition processes by slowing down reaction rates. Investigations were also carried out to assess the capability of an existing diesel engine model, based on the filling and emptying technique, suitably modified such that it could be used to simulate non-air performance. The modifications to the model to allow parametric comparisons to be undertaken of non-air brake performance indicators were found to be within 5 per cent of experimental values.

Fire Extinguishing Effect Of Mixed Agents Of Halon 1301 And Inert Gases

Multiplier effect of mixed agents of trifluorobromomethane (halon 1301) and inert gases on flame extinction has been investigated, for the purpose of minimizing the use of halons. The inert gases examined are argon, nitrogen and carbon dioxide. The fire-extinguishing efficiency was determined by flame-extinguishing concentrations for n-heptane measured with a cup burner. An additive-property equation was derived by thermodynamic considerations to predict the fire-extinguishing efficiency of mixed agents and used as a measure of multiplier-effect test. The mixed agents of halon 1301 and inert gases showed multiplier effect. There were the optimized mixing ratios of the most effective agents. Flame-extinction temperatures were calculated for the n-heptane flames with the flame extinguishing concentrations of agents. The temperatures suggested that the chemical effect of halon 1301 was enhanced with decreasing the flame temperature by the addition of inert gases. The flame temperature and the concentration of halon 1301 determined strength of the multiplier effect of halon 1301 and inert gas.

チタンのプラズマ浸炭窒化による硬質Ｔｉ（Ｃ，Ｎ）層の作製

Plasma carbonitriding process has been applied to preparation of hard Ti(C, N) layer on the surface of titanium plate at relatively low temperatures. The formation of thick Ti(C, N) layer was confirmed by means of XRD and ESCA measurements and Vickers hardness test. The carbonitriding was carried out in an r.f. (4 MHz) glow plasma generated in quartz tube using N2–C2H2 gas mixtures. The Ti(C, N) layer consisted of continuous solid solution of TiN and TiC. With increase in the C2H2 ratio of carbonitriding gas, the thickness of carbonitriding layer somewhat decreased, but the friction coefficient of the surface was improved and its value was similar with that of commercial TiN films for cutting tools. The addition of inert gas (He, Ar) into N2–C2H2 gas somewhat decreased the thickness of the carbonitriding layer, while the surface roughness of carbonitrided Ti was rather improved. It may be presumed that the bombardment of massive inert gas ion assists to make the surface more smooth.

Quantum yield in the gas phase photolysis of perfluoroacetyl chloride: a comparison with related compounds

The photolysis of perfluoroacetyl chloride vapour was studied in the pressure range 4.6–59.9 Torr and with addition of inert gas up to 535.2 Torr using light of 254 and 280 nm. The quantum yield for the decomposition of CF 3COCl taken as Φ[CF 3Cl+2C 2F 6] = 0.98±0.13 was not affected by the total pressure, the intensity and the wavelength of the light within the studied range of conditions. In the presence of c-C 6H 12 a clear hydrogen abstraction reaction took place indicating the presence of CF 3 radicals. An upper limit for the rate of hydrogen abstraction of log k H(cm 3 mol −1 s −1) = 7.9 at 298 K was obtained. Light emission was not observed over the range 330–600 nm. Mechanisms for the decomposition of perfluoroacyl halides are discussed.

Optical emissions during plasma assisted chemical vapor deposition of diamond-like carbon films

The deposition of diamond-like carbon (DLC) films onto silicon wafers and polyethyleneterephthalate (PET) from methanehydrogen gas mixtures by plasma assisted chemical vapor deposition was investigated by optical emission spectroscopy. Film growth rates, crack formation, and average electron energy in the plasma were analyzed for various deposition conditions. The cracks in the DLC films deposited onto PET could be removed by increasing the hydrogen content in the gas mixture. No adjustment of ion energy, substrate temperature control, or addition of inert gas was necessary to avoid crack formation. In the commonly used range of bias voltage above 500 V, the intensity of the Hα line (656.3 nm) correlated well with the film deposition rate. The hydrogen peak intensity can be used for on-line, non-contact, instantaneous monitoring of the deposition rate.

Parameter Optimization for the Arc-Adlc-Deposition Process

ABSTRACTOne method used by the industry for the deposition of thin carbon films is the dc cathodic arcion plating process. The evaporation of a graphite cathode by a high energy arc beam results in the production of carbon atoms, ions and macroscopic graphitic fragments. All these particles influence the film growth, the structure and therefore the film properties. The incorporation of the macroscopic graphitic fragments can be avoided by the use of mechanical or magnetic filters in front of the cathode. These filters prevent the direct bombardment of the substrates with particles. This particle separation involves decreased substrate current densities and this means lower deposition temperature (< 200°C) and growth rates. With the addition of inert (argon) and reactive gases (nitrogen and methane) and the use of a bias voltage on the substrate economical deposition rates of 2-4 μm/h and good adhesion on various materials can be reached.This paper describes the production of amorphous hydrogen and hydrogen-free carbon films by a modified cathodic arc evaporation process using a simple mechanical filter for particle reduction. It shows the influence of some process parameters on the optimization of the process stability and process efficiency. Some characteristic properties of these coatings are shown by an example.

A small ionization chamber appropriate to tritium processing systems

Small sized ionization chambers are attractive as a continuous tritium flow monitor in the fuel processing systems. We made a small ionization chamber and examined some basic properties of it such as saturation-current characteristics, concentration and/or pressure dependence of the ionization current, and impurity gas effects. A small ionization chamber of 1.9 cm 3 in volume showed satisfactory saturation-current characteristics above 20 V, and also gave a good linear relationship between ionization current and tritium concentration in a wide range from 1 × 10 −6 to 3 × 10 −1 Ci/cm 3 under condition of 1 atm. The pressure dependence of the ionization current was analyzed through a simple two-dimensional model taking account of the energy consumption of β particles in the chamber. Addition of inert gases to tritium gas caused the ionization current to increase. This phenomenon was attributed to the change in the stopping power and W value with the mixing up of different gases.

Dynamics of Laser Ablation and Vaporization of PbZr0.54Ti0.66O3: Laser Fluence and Ambient Gas Effects

AbstractA systematic study of the gas phase products observed from the pulsed laser vaporization of a PbZro.54Ti0.46O3target was performed as a function of laser fluence and ambient gas pressure. At low fluences, ≤0.3 J/cm2, only Pb and PbO were observed, while at higher fluences, between 0.3 - 1.3 J/cm2, neutral atomic species Pb, Zr, and Ti were detected. Small oxide molecules and atomicions were also observed. These regimes are associated with two ejection mechanisms: thermal evaporation and ablation, respectively. No direct evidence of chemical reactions was found over the gas pressure range explored (0-5 mTorr). Within the 25 cm reaction cell distance however, the addition of both inert and reactive gases greatly changed the velocity distributions of the ejected species. The decrease in velocity (energy) as a function of gas pressure was due to physical scattering and could be modeled as a pseudo-first order bimolecular collision process. The scattering rate increased linearly with the physical cross-section of the background gas and was independent of the kinetic energy of the ablated species.

Current density effects and the importance of charge transfer processes in the radiolysis of methane - Astrophysical implications

view Abstract Citations (4) References (17) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Current Density Effects and the Importance of Charge Transfer Processes in the Radiolysis of Methane: Astrophysical Implications Sack, N. J. ; Schuster, R. ; Hofmann, A. ; Khedim, A. ; Koppmann, R. Abstract In order to get information about the influence of irradiation parameters and the addition of inert gases in radiolysis processes of astrophysical interest, methane gas targets were irradiated with 6.5 MeV protons at a pressure of 1 bar and room temperature. The yields for higher hydrocarbons like ethane or propane were obtained by gas chromatography analysis of irradiated gas samples. A series of experiments was performed adding inert gases like helium, argon, or nitrogen in various quantities to the methane gas. Charge transfer reactions were found to play an important role in the reactions induced by the irradiation. Current density and total absorbed dose were also proved to have large influence on the yields of produced hydrocarbons. Estimations of electron, ion, and radical densities are made, leading to an understanding of the reaction mechanism and comparisons to other rate coefficients are given. The relevance of the investigations for the chemistry and the simulation of various astrophysical systems is given. Publication: The Astrophysical Journal Pub Date: September 1990 DOI: 10.1086/169121 Bibcode: 1990ApJ...360..305S Keywords: Charge Transfer; Current Density; Interstellar Chemistry; Methane; Radiolysis; Planetary Evolution; Rare Gases; Atomic and Molecular Physics; LABORATORY SPECTRA; MOLECULAR PROCESSES full text sources ADS |