Combustion of boron particles at atmospheric pressure

Maček, Andrej; Semple, J. McKenzie

doi:10.2514/6.1969-562

Cited by 33 publications

(40 citation statements)

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“…In any case, it is agreed by many, including King, that the ignition of boron can occur sooner if the oxide layer was somehow removed quicker. Experimental evidence has shown that ignition delay is reduced in atmospheres containing water vapor [14,15]. Other experiments have shown changes in ignition delay with atmospheres containing other compounds, such as …”

Section: Goals Of Current Researchmentioning

confidence: 94%

“…They noticed that the two stages tend to merge when they use low oxygen mole ratios. As for the quantitative results, they observed ignition temperature to average out to be 1992±16 K when no water vapor was added and I I Delay measured with a flat flame burner from point of first glow to point of bright I ~glow [ 14]. In a later study [22], Macek and Semple carried out combustion studies at elevated 3 pressures and used a focused laser to energize the particle.…”

Section: Imentioning

confidence: 99%

“…Very significant boron combustion research were those experiments conducted by Macek and Semple [14]. Single particles of crystalline boron, which were separated into two samples having average diameters of 34.5 and 44.2 gm, were injected into a stream of hot oxidizing gas generated by a gas-burner at atmospheric pressure.…”

Section: Imentioning

confidence: 99%

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Shock initiation of crystalline boron in oxygen and fluorine compounds

Krier

Burton

Pirman

et al. 1996

Journal of Propulsion and Power

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Section: Goals Of Current Researchmentioning

confidence: 94%

Section: Imentioning

confidence: 99%

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Shock initiation of crystalline boron in oxygen and fluorine compounds

Krier

Burton

Pirman

et al. 1996

Journal of Propulsion and Power

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“…В сухой атмосфере при прочих равных условиях общий процент воспламенения выше, чем в при-сутствии водяного пара [26]. Реализовать режим парофазового горения бериллия в атмосфере водяного пара или по крайней мере повысить температуру таких образцов до 2200 К в атмосфере водяного пара невозможно.…”

Section: основные закономерности воспламенения бериллияunclassified

“…Однако измеренные значения  ип оказались пропорциональными приблизительно d 2,5 . Это от-клонение может быть объяснено потерями тепла в результате радиации, которые вследствие высокой из-лучательной способности бериллия не являются пренебрежимо малыми [26]. Чем больше концентрация частиц металла, тем ниже температура их воспламенения из-за так называемого «коллективного эффекта».…”

Section: основные закономерности воспламенения бериллияunclassified

Some Characteristics of Fine Beryllium Particle Ignition and Combustion

Давыдов¹,

Kholopova²,

Kolbasov³

2010

PAST-TF

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Бериллиевая пыль будет образовываться при взаимодействии плазмы с бериллиевым защитным покрытием первой стенки реактора ИТЭР. Экзотермические реакции между этой пылью и водяным паром или воздухом, которые могут про никнуть в вакуумную камеру при некоторых авариях, представляют опасность для реактора. В данной статье даётся обзор результатов исследований воспламенения и горения бериллия, в основном мелких бериллиевых частиц (пыли). Химически активная среда и повышенная температура являются предпосылками для их воспламенения. Оксидные плёнки, создающие диффузионный барьер на поверхности бериллиевых частиц при окислении, предшествующем горению, затрудняют воспламенение. Температу-ра, при которой начинается горение частиц, зависит от температуры пламени, размера частиц, состава горючей смеси, скорости подвода тепла и других факторов. В смесях, обогащённых горючим компонентом, температура пламени, необходимая для вос-пламенения отдельных частиц, близка к температуре кипения бериллия.Ключевые слова: бериллиевая пыль, окисление, воспламенение, горение, оксидная плёнка. SOME CHARACTERISTICS OF FINE BERYLLIUM PARTICLE IGNITION AND COMBUSTION. D.A. DAVYDOV, O.V. KHOLOPOVA, B.N. KOLBASOV. Beryllium dust will be produced under plasma interaction with beryllium armor of the first wall in ITER. Exothermal reaction of this dust with water steam or air, which can leak into the reactor vacuum chamber in some accidents, gives concern in respect to reactor safety. Results of studies devoted to ignition and combustion of fine beryllium particles are reviewed in this paper. A chemically active medium and elevated temperature are prerequisite to the ignition of beryllium particles, which is hampered by oxide films, forming a diffusion barrier on the particle surface as a result of pre-flame oxidation. The temperature to initiate combustion of particles depends on flame temperature, particle size, composition of combustible mixture, heating rate and other factors. In mixtures enriched with combustible, the flame temperature necessary to ignite individual particles approaches the beryllium boiling temperature.

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Effect of Initial Oxide Layer on Ignition and Combustion of Boron Powder

Ao¹,

Wang²,

Li³

et al. 2013

Propellants Explo Pyrotec

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Only few data exist for experimental studies on ignition and combustion of boron particles with initial oxide thickness. The oxidation, ignition and combustion characteristics including the onset temperatures, weight gain, apparent activation energy, emission spectra during combustion, and ignition delay time of crystalline boron powders with different initial oxide thickness (x0) were studied by a laser ignition and thermogravimetric (TG) analyses. Simulations of the kinetics of oxide layer during boron ignition were conducted using a common model. The results indicated that the onset temperature was approximately 775 °C, independent of x0. The total weight gain decreased with increasing x0, whereas the weight gain at 775 °C did not change. The apparent activation energy was found to be insensitive to x0 and had a constant value of about 210 kJ mol−1. The intensity of the emission spectra gradually decreased while the ignition delay time increased with increasing x0. Numerical simulation showed that the removal rate of oxide layer enhanced with increasing x0. The experimental results revealed that the oxidation of boron powder was no diffusion‐controlled process at low temperatures. But the diffusion of oxygen could become important to the oxidation reaction at high temperatures

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Combustion of boron particles at atmospheric pressure

Cited by 33 publications

References 1 publication

Shock initiation of crystalline boron in oxygen and fluorine compounds

Shock initiation of crystalline boron in oxygen and fluorine compounds

Some Characteristics of Fine Beryllium Particle Ignition and Combustion

Effect of Initial Oxide Layer on Ignition and Combustion of Boron Powder

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