Combustion Of Carbon Monoxide Research Articles

Basic experiments during loss of vacuum event (LOVE) in fusion experimental reactor

If a loss of vacuum event (LOVE) occurs due to damage of the vacuum vessel of a nuclear fusion experimental reactor, some chemical reactions such as a graphic oxidation and a buoyancy-driven exchange flow take place after equalization of the gas pressure between the inside and outside of the vacuum vessel. The graphite oxidation would generate inflammable carbon monoxide and release tritium retained in the graphite. The exchange flow through the breaches may transport the carbon monoxide and tritium out of the vacuum vessel. To add confidence to the safety evaluations and analyses, it is important to grasp the basic phenomena such as the exchange flow and the graphite oxidation. Experiments of the exchange flow and the graphite oxidation were carried out to obtain the exchange flow rate and the rate constant for the carbon monoxide combustion, respectively. These experimental results were compared with existing correlations. We plan a scaled-model test and a full-scale model test for the LOVE.

円管内混合気体層流における黒鉛酸化時の物質伝達

Experiments and numerical analyses on mass transfer in a gas mixure laminar flow through a circular graphite tube accompanied with graghite oxidation were performed to clarify characteristics of graphite corrosion in connection with the primary cooling pipe rupture accident in a high temperature gas cooled reactor. In the experiment, inlet Reynolds numbers ranged from 16 to 320, graphite temperatures from 600 to 1, 050°C and inlet oxygen mass fractions from 10 to 50%. IG-110 and PGX graphites were used. The mass transfer coefficients in the experiment at a high temperature were less than those obtained on the basis of analogy between heat and mass transfer. It was found from the numerical analysis that the reduction of mass transfer coefficient resulted from the injection flow from the wall. The mass fractions of carbon monoxide and carbon dioxide in the experiment were well predicted on the basis of the one-dimensional numerical analysis in which graphite oxidation and carbon monoxide combustion were taken into consideration.

Numerical Analysis of Mass Transfer with Graphite Oxidation in a Laminar Flow through a Circular Tube.

Mass transfer has been numerically studied in a laminar flow through a circular graphite tube at high temperature. Homogeneous (carbon monoxide combustion) and heterogeneous (graphite oxidation) chemical reactions occur in the multicomponent gas mixture : helium, oxygen, carbon monoxide and carbon dioxide. The effects of carbon monoxide combustion and graphite oxidation on the mass transfer coefficients were quantitatively and qualitatively clarified in the range of 50 to 1000 of inlet Reynolds number, 0 to 0.5 of inlet oxygen mass fraction and 800 to 1600°C of temperature.

Measurements of reactant temperature and free-radical concentrations during the oscillatory combustion of hydrogen and carbon monoxide in a CSTR

Experimental studies in which the phase relationship between a reactive intermediate concentration and reactant temperature during the gas-phase, oscillatory combustion of hydrogen + carbon monoxide mixtures in a non-adiabatic CSTR are reported. This combustion reaction and its counterpart, hydrogen oxidation, constitutes the simplest of the non-isothermal, quadratic autocatalytic systems. The hydroxyl radical (OH) is a primary propagating species. Measurements of the laser-induced absorption spectrum of OH during oscillatory reaction led simultaneously, via data capture and analysis by computer, to absolute concentrations of the species and to the reactant temperature. The results show that there is a considerably reduced reactivity of the carbon monoxide-containing reaction when compared with the results obtained previously from hydrogen oxidation. The OH concentration and reactant temperature remain in phase during the oscillatory combustion.

The combustion of carbon monoxide in a two-zone fluidized bed

The oxidation of CO to CO 2 has been studied in a two-zone fluidized bed of silica sand heated externally to 1000°C. The lower, fuel-rich, part of the bed is fluidized by a primary mixture of N 2 + CO, whereas the upper zone is fluidized by O 2 + N 2, premixed before being introduced through a sparger located roughly in the middle of the bed. First, the mixing characteristics of such a bed were studied and the cross-flow factor was measured for secondary bubbles in the upper fuel-lean zone. Then with mixing the burning of CO + O 2 occurring in the upper zone, concentration profiles were measured throughout the bed and freeboard. These studies indicate that CO and O 2 do not react in the particulate (emulsion) phase, but do react in the bubble phase as well as in the freeboard. The addition of CO 2 confirms that the strong inhibition of reaction in the particulate phase is a chemical effect and not a heat transfer effect, as has been suggested. In fact, combustion of CO is quenched in the particulate phase primarily by radicals recombinining and also by electronically excited species being deactivated on the huge available surface areas of solids, although homogeneous chain termination is also possible, as with the addition of CO 2. The implications of there being no combustion of gases within the particulate phase of a fluidized bed are discussed, especially with respect to coal combustion in these systems. The rate constant for CO and O 2 reacting in the bubble phase and freeboard was determined.

Effect of passivation of heavy metals on activity of a promoter of carbon monoxide oxidation

The deactivating effect of heavy metals (nickel, vanadium) that accumulate on the cracking catalyst during the refining of heavy crude, is eliminated by means of passivating additives based on antimony and tin [i, 2]. Moreover, in catalytic cracking units, wide use is made of additives that ensure the complete combustion of carbon monoxide in the regenerator; i.e., promoters of oxidation [3, 4]. The simultaneous use of two different kinds of additives in industrial plants has led to the appearance of contradictory information about the action of passivators on the activity of promoters [5, 6].

Regeneration of cracking catalyst influence of the homogeneous CO postcombustion reaction

AbstractAccompanying the fast burning of coke on a cracking catalyst is the oxidation of the coke burning product, carbon monoxide. This carbon monoxide combustion involves a homogeneous and a catalytic reaction. The homogeneous reaction was isolated by injecting pulses of CO, CO2 and O2 into a laboratory scale reactor at controlled temperature and pressure. The coke burning and catalytic CO combustion reactions were studied by oxidizing coke deposited on a zeolitic catalyst in the same microcatalytic reactor. The role of homogeneous CO oxidation during coke combustion under these conditions was determined.

Influence of natural convection and diluent inerting on H 2 and CO oxidation in the reactor cavity

The question of complete in-cavity oxidation of combustible gases produced by core-concrete interactions following vessel breach has been investigated. It is overly optimistic to assume a complete oxidation because a variety of phenomena, such as steam inerting and oxygen transport by natural convection, may influence the degree of in-cavity oxidation that takes place. HECTR analyses of an ice-condenser containment during an S2HF drain-closed accident show that the in-cavity oxidation process is limited by the rate at which oxygen is transported into the reactor cavity region. Accumulation and subsequent combustion of hydrogen and carbon monoxide in the upper and lower compartments generate a peak pressure of 384 kPa (56 psig) at 7.4 h, that an earlier IDCOR analysis did not predict.

Adsorption calorimetry : An overview of its practice and applications

Chemisorptions and catalyzed reactions, like any chemical reaction, are associated with changes of enthalpy and can therefore be studied by means of calorimeters. Many calorimeters, operating on different principles, have indeed been used for this purpose, as it will be attempted to show in a brief review (ref. 1). In our opinion, however, heat-flow calorimeters are particularly convenient for these studies (ref. 2). They offer a number of advantages which will be illustrated by means of selected examples. Heat-flow calorimetry, preferably in association with other physico-chemical or physical techniques, may be used to describe the surface properties of a solid. It will be shown that, for instance, differential heats of adsorption of ammonia may serve to quantitatively describe surface acidity in small-pore zeolite, e.g. H-ZSM5, and thus to complement the information provided by i.r. spectroscopy (ref. 3). Information on the bonds energy, deduced from calorimetric data, is needed to achieve a theoretical description of the adsorbate-adsorbent bond. It will be shown, for instance, that, in the case of the adsorption of hydrogen on nickel-copper alloys, a correlation between heats of adsorption and surface magnetic properties can be demonstrated. The correlation indicates that the energy of the bond between adsorbed hydrogen and nickel atoms is regulated by the electron density of states, near the Fermi level, for the metal surface (ref. 4). Adsorption of one, at least, of the reagents is a necessary step in all heterogeneously catalyzed reactions. Calorimetric investigations of the adsorptions of the pure reagents on the catalysts may therefore provide some information on the catalytic reaction itself. It appears, for instance, that there exists an inverse linear correlation between the activity of silver catalysts for the epoxidation of ethylene and the bonding energy of oxygen at their surface (ref. 5). The change of enthalpy associated with the reaction is, of course, not modified by the presence of the catalyst. Therefore, thermochemical cycles, based on experimentally determined heats of adsorption of interaction of reagents, introduced successively at the catalyst surface, may give indication on the most probable reaction mechanism, in the case of “simple” catalytic reactions. The recorded heat of reaction, however, may differ from the expected one when secondary reactions, eventually leading to the catalyst activation or deactivation, take place. The calorimetric study of the catalytic reaction, when a steady state of activity is not yet established, may therefore give information on the catalysts evolution or even on the reaction mechanism. These applications of calorimetry will be illustrated by various studies of the combustion of carbon monoxide on divided nickel oxide catalysts at 300 and 473 K (ref. 6). Heat-flow calorimeters are also used for kinetic studies. Several examples will be presented to show how reaction orders, kinetic laws and, in favourable cases, activity spectra of the catalysts surface can be determined (ref. 1). In the case of fast processes, deconvolution of the calorimetric data must be achieved (ref. 7).

Catalytic Combustion in Cylindrical Channels: A Homogeneous-Heterogeneous Model

Abstract The behavior of reactors in which homogeneous and heterogeneous reactions occur simultaneously may be of interest in high temperature catalytic processes including catalytic combustion in tubes or monoliths. A two dimensional model of a laminar flow, adiabatic, tubular reactor for the combustion of carbon monoxide was developed. Three variations of the model were examined (1) the homogeneous only case, (2) the heterogeneous only case, and (3) the homogeneous-heterogeneous case. The differential equations were solved for the case of a reactor with an inside diameter of 0.153 cm with inlet concentrations of 4 mole percent CO, 20 mole percent O2 and, 76 mole percent N2. The behavior of the reactor approaches that of the heterogeneous only model for inlet temperatures less than 650 K. Reactor behavior approaches that of the homogeneous only model for inlet temperatures greater than 1150 K. Between 650 and 1150 K both reactions must be considered. For inlet temperatures near the upper end of this rang...

An attempt to correlate the kinetic and energetic data applying to excited species occurring in carbon monoxide combustion

The present state of research on the carbon monoxide-oxygen reaction may be characterized by the presence of uncorrelated interpretations concerning the energetic and kinetic aspects of its mechanism. It is the purpose of this work to establish the necessary relation between the characteristic emissive properties of the reaction [1, 2, 3] and the kinetics of the reaction evolution [4, 5, 6], with the underlying premise that both aspects are linked by the same energetic species. Thus, this paper may be viewed as an attempt to unify the different concepts accepted about energetic and kinetic aspects of the carbon monoxide-oxygen reaction.

Role of quadratic breaking of chains with the combustion of carbon monoxide

Role of quadratic breaking of chains with the combustion of carbon monoxide

Intermittent combustion of carbon monoxide under static conditions

Intermittent combustion of carbon monoxide under static conditions

Study of ignition of carbon monoxide with additions of halogen hydrocarbons near the first ignition limit

1. Tetrafluorodibromomethane inhibits the combustion of carbon monoxide, taking place in the presence of traces of hydrogen-containing compounds. 2. The rate constant of the reaction between atoms of hydrogen and tetrafluorobromomethane has been determined from data on the inhibition of the ignition of carbon monoxide at 650°.

Anomalously deep burning-out with the combustion of carbon monoxide

Anomalously deep burning-out with the combustion of carbon monoxide

Measurement of atomic oxygen and nitrogen oxides in jet-stirred combustion

Direct spectroscopic measurement of continuum chemiluminescence at 3500 Å, due presumably to the reaction CO+O→CO2+hv, was used to determine super-equilibrium atomic oxygen concentrations in situ for near-homogeneous, continuous-combustion of either carbon monoxide or methane with 133% theoretical air in a jet-stirred reactor operated near blowout, at atmospheric pressure. Reactor CO and NOx concentrations were measured by gas sampling. The motivation for this initial optical spectroscopic examination of the jet-stirred reactor was the elucidation of NOx formation in high-intensity, backmixed combustion. Measured gas temperatures were in the ranges T=1350 to 1500°K for carbon monoxide combustion, and T=1400° to 1800°K for methane combustion. Peak atom oxygen concentrations occurred just prior to reactor blowout. Partial equilibrium was indicated for the reactions CO+OH⇆CO2+H and O2+H⇆O+OH, at throughput rates sufficiently less than reactor blowout. Atomic oxygen measurements were used to compare NOx measurements with values predicted for plausible NOx kinetic formation mechanisms, considering only O, OH, and H as reaction radical intermediates. Agreement between the comparisons was obtained only for carbon monoxide combustion, indicating that nitrous oxide probably acts as an intermediate in NOx formation in the presence of super-equilibrium concentrations of atomic oxygen.

The Role of Energy-Releasing Kinetics in NOxFormation: Fuel-Lean, Jet-Stirred CO-Air Combustion

Abstract Oxides of nitrogen concentrations, temperatures and mass flow rates near reactor blowout have been measured for chemically rate-limited, fuel-lean combustion of carbon monoxide with moist air in a jet-stirred reactor at 0.5 and 1 atmosphere. Comparisons with predictions obtained by modeling the jet-stirred reactor as a micromixed perfectly stirred reactor are used to examine the detailed influences of energy-releasing kinetic processes on NOx formation. Reaction radical intermediates and, in particular, oxygen atoms are shown to play a key role in this influence. For fuel-lean combustion, under conditions of intense turbulence and backmixing, super-equilibrium concentrations of oxygen atoms cause N2 O to act as an important intermediate leading to NOx formation. Measurements indicating the influence of finite mixing on experimental reactor performance and NOx emissions are presented as well.

Utilization of the heat of combustion of carbon monoxide in an open-hearth furnace during oxygen blowing of the bath

Utilization of the heat of combustion of carbon monoxide in an open-hearth furnace during oxygen blowing of the bath

Estimation of Exposure from the Specially Developed Device (Co-non) for the Perfect Combustion of Carbon Monoxide Attached to a Car Engine

Estimation of Exposure from the Specially Developed Device (Co-non) for the Perfect Combustion of Carbon Monoxide Attached to a Car Engine

The effect of oscillatory combustion on the formation of atmospheric pollutants

The difference between the relaxation times of the mechanical and thermal transport processes which occur in flow combustors often leads to a coupling phenomenor, which may result in severe acoustical oscillations. Previously reported experiments have indicated that the concentrations of certain chemical species may be significantly affected by these pressure-temperature oscillations. Some chemical species, such as the oxides of nitrogen, which are apparently enhanced, are directly involved in the formation of atmospheric pollutants and chemical smog. Because oscillatory combustion occurs in many industrial applications, an understanding of the complex chemical thermodynamics of combustion systems is very important. In this work approximate integration techniques have been employed to solve the set of simultaneous kinetic rate equations which describe the oscillatory combustion of certain hydrocarbons. The dynamic concentrations for each chemical species have been calculated as a function of time and position in a model flow combustor. Three chemical systems were investigated: the combustion of carbon monoxide in oxygen, the combustion of carbon monoxide in air, and the products of the combustion of methane in air. In addition, calculations of the point-to-point equilibrium concentrations for the chemical systems investigated were made for comparison. Some major conclusions reached as a result of this analytical study were as follows: 1. Pressure-temperature oscillations significantly affect the concentrations of several “trace” components which contribute to air pollution. 2. The amplitude of the temperature oscillations seems to be of more importance than the frequency of the oscillations for the particular combustor model chosen for this study. The effects due to amplitude become more significant with increased temperature. 3. Deviation from equilibrium in flow combustors is very significant for important trace components such as monatomic oxygen and nitric oxide.