Catalytic inhibition of laminar flames by transition metal compounds

Linteris, Gregory T.; Rumminger, M D.; Babushok, Valeri I.

doi:10.1016/j.pecs.2007.08.002

Cited by 101 publications

(59 citation statements)

References 130 publications

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“…SbBr3, as the actual flame retardant, acts as a radical interceptor like HCl or HBr. It is thought that the trivalent antimony halide facilitates the formation of halogen radicals, and is more effective than HBr [26] at catalysing the recombination of hydrogen.…”

Section: Flame Retardant Mechanism Of Antimony-bromine Systemsmentioning

confidence: 99%

The effect of gas phase flame retardants on fire effluent toxicity

Molyneux

Stec

Hull

2014

Polymer Degradation and Stability

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Standard industry formulations of flame retarded aliphatic polyamides, meeting UL 94 V-0, have been burned under controlled conditions, and the yields of the major asphyxiants, carbon monoxide (CO) and hydrogen cyanide (HCN) have been quantified. Although both the combination of aluminium phosphinate and melamine polyphosphate, and the combination of brominated polystyrene and antimony oxide, inhibit combustion reactions in the gas phase, this study shows that the phosphorus causes a much smaller increase in the CO and HCN yields than antimonybromine. The mechanisms of CO and HCN generation and destruction are related to the flame inhibition reactions. Both CO and HCN form early in the flame, and the OH radical is critical for their destruction. Crucial, in the context of the flame inhibition mechanism, is the observation that the phosphorus system reduces the H and O radical concentrations without a corresponding decrease in the OH radical concentration; conversely, the bromine system reduces all three of the key radical concentrations, H, O and OH, and thus increases the fire toxicity, by inhibiting decomposition of CO and HCN. Moreover, while the phosphorus flame retardant is effective as an ignition suppressant at lower temperatures (corresponding to early flaming), this is effect "switches off" at high temperatures, minimising the potential increase in fire toxicity, once the fire develops. Since flame retardants are most effective as ignition suppressants, and at the early stages of flaming combustion, while most fire deaths and injuries result from toxic gas inhalation from more developed fires, it is clearly advantageous to have an effective gas phase flame retardant which only causes a small increase in the toxic product yields.

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Section: Flame Retardant Mechanism Of Antimony-bromine Systemsmentioning

confidence: 99%

The effect of gas phase flame retardants on fire effluent toxicity

Molyneux

Stec

Hull

2014

Polymer Degradation and Stability

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“…Consequently, detailed thermo-transport and kinetic models have been developed to simulate and analyze methane flames in a variety of configurations. Considerable research has also been reported on the extinction and blowout of methane-air flames using various diluents, such as CO 2 , N 2 , H 2 O, and chemical agents (Linteris et al 2008;Aggarwal 2009). Most of these studies and the associated models can be readily used for analyzing the combustion and emission characteristics of biogas, whose main constituents are CH 4 and CO 2 with small traces of H 2 O and N 2 .…”

Section: Biogas Combustion and Emission Characteristicsmentioning

confidence: 99%

Using Petroleum and Biomass-Derived Fuels in Duel-fuel Diesel Engines

Xiao

2014

Novel Combustion Concepts for Sustainable Energy Development

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There is worldwide interest in developing renewable energy sources in a sustainable manner. Syngas and biogas offer significant potential in this context, as these fuels offer great flexibility with regard to their production and utilization. This chapter provides an overview of research dealing with the combustion and emission characteristics of these fuels, both as stand-alone fuels or by blending with petroleum fuels. Conversion methods for producing these fuels from different biomass sources are also briefly reviewed. While the syngas composition can vary widely, it generally has lower heating value, lower density, higher mass diffusivity, higher flame speeds, and wider flammability limits compared to hydrocarbon fuels. Moreover, its combustion leads to almost zero soot emission, although NO x emission may be a concern depending upon its composition and operating temperatures. Similarly, biogas has lower heating value compared to hydrocarbon fuels, and its ignition and combustion characteristics can vary noticeably depending upon its composition. While there have been few studies focusing directly on biogas combustion, there is extensive literature on methane combustion, including ignition, extinction, flammability limits, flame speeds, cellular instabilities, and emissions. Fundamental combustion aspects requiring further research include cellular instabilities, flame stabilization and blowout behavior, turbulent flames, and emission characteristics. Such efforts would lead to the development of optimized systems for producing these fuels and provide guidelines for optimizing their composition for a given set of operating conditions. The use of syngas and biogas in dual-fuel diesel engines has been a subject of numerous experimental and computational studies. A general observation is that the engine performance and emission characteristics are significantly modified by the presence of gaseous fuel. While the heat release in a diesel engine generally occurs through a hybrid combustion mode, involving rich premixed combustion and diffusion combustion, that in a dual-fuel engine also involves a lean combustion mode with a propagating flame. The dualfuel operation at high-load conditions can provide significant reduction in soot and CO soot emissions, while maintaining the engine efficiency, provided the injection characteristics including the amount of pilot fuel can be optimized. However, the NO x emission may increase, requiring a suitable strategy for lowering the temperatures. The dual-fuel strategy may be less effective at low load, resulting in lower thermal efficiency and higher UHC and CO emissions. Future work should be directed at optimizing the various parameters, such as injection timing, amount of pilot fuel injected, EGR, and multiple injections.

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“…Mixtures were prepared using the partial pressure method with H 2 (99.99%), CO (99.99%), O 2 (99.5%), He (99.995%), Ar (99.997%), and CO 2 (99.99%). High purity CO stored in an aluminum cylinder was used to ensure no contamination with iron pentacarbonyl, Fe(CO) 5 , which is readily formed in steel CO cylinders [50] and is a known flame inhibitor [51][52], as discussed in Refs. [53,5].…”

Section: Mass Burning Rate Measurements and Kinetic Analysis Of H 2 /mentioning

confidence: 99%

Reduced and Validated Kinetic Mechanisms for Hydrogen-CO-sir Combustion in Gas Turbines

Ju¹,

Dryer²

2009

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Rigorous experimental, theoretical, and numerical investigation of various issues relevant to the development of reduced, validated kinetic mechanisms for synthetic gas combustion in gas turbines was carried out -including the construction of new radiation models for combusting flows, improvement of flame speed measurement techniques, measurements and chemical kinetic analysis of H 2 /CO/CO 2 /O 2 /diluent mixtures, revision of the H 2 /O 2 kinetic model to improve flame speed prediction capabilities, and development of a multi-time scale algorithm to improve computational efficiency in reacting flow simulations. Executive SummaryRigorous experimental, theoretical, and numerical investigation of various issues relevant to the development of reduced, validated kinetic mechanisms for synthetic gas combustion in gas turbines was carried out -including the construction of new radiation models for combusting flows, improvement of flame speed measurement techniques, measurements and chemical kinetic analysis of H 2 /CO/CO 2 /O 2 /diluent mixtures, revision of the H 2 /O 2 kinetic model to improve flame speed prediction capabilities, and development of a multi-time scale algorithm to improve computational efficiency in reacting flow simulations.An accurate spectral dependent radiation model is developed to predict flame speed and flammability of H 2 /CO/CO 2 /H 2 O/Air mixtures. The results showed that radiation reabsorption significantly extended the flammability limits. It was also demonstrated that accurate prediction of coal syngas flammability is not possible without appropriate consideration of radiation absorption by CO 2 and H 2 O.Methodologies to improve flame speed measurement were developed by experimental and theoretical investigation of the effect of non-spherical (i.e. cylindrical) bomb geometry on the evolution of outwardly propagating flames and the determination of laminar flame speeds. The cylindrical chamber boundary modifies the propagation rate through the interaction of the wall with the flow induced by thermal expansion across the flame (even with constant pressure), which leads to significant distortion of the flame surface for large flame radii. It was determined that these departures from the unconfined case, especially the resulting non-zero burned gas velocities, can lead to significant errors in flame speeds calculated using the conventional assumptions, especially for large flame sizes.The methodology to estimate the effect of nonzero burned gas velocities is applied to correct the flame speed for non-zero burned gas speeds, in order to extend the range of flame radii useful for flame speed measurements. Under the proposed scaling, the burned gas speed can be well approximated as a function of only flame radius for a given chamber geometry -i.e. the correction function need only be determined once for an apparatus and then it can be used for any mixture. Results indicate that the flow correction can be used to extract flame speeds for flame radii up to 0.5 times the wall radius wi...

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Catalytic inhibition of laminar flames by transition metal compounds

Cited by 101 publications

References 130 publications

The effect of gas phase flame retardants on fire effluent toxicity

The effect of gas phase flame retardants on fire effluent toxicity

Using Petroleum and Biomass-Derived Fuels in Duel-fuel Diesel Engines

Reduced and Validated Kinetic Mechanisms for Hydrogen-CO-sir Combustion in Gas Turbines

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