Modeling of the mechanism of heterogeneous inhibition of the active flame centers of a jet burning system by fire extinguishing powder particles

The relevance of the work is due to the lack of a physical interpretation of the process of extinguishing jet burning systems with fire extinguishing powders, which is important for ensuring effective fire extinguishing at gas and oil complexes and hazardous chemical industries. A mathematical model of the reaction kinetics of heterogeneous inhibition of active flame centers of a jet burning system by fire extinguishing powder particles in an unsteady mode is considered in the approximation of a purely molecular transfer of matter in the reaction zone. The regularities of the mechanism of heterogeneous inhibition of the active flame centers by the particles of the extinguishing powder under conditions when the active particles of the combustion products participate not only in diffuse, but also in convective transport are established. It is shown, that the convective motion of the active flame centers increases the reaction rate of heterogeneous inhibition of their particles of the extinguishing agent. The results obtained allow us to optimize the conditions for the supply of fire extinguishing powder to the jet burning medium for effective flame suppression.

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Efficiency of heterogeneous inhibition of active flame centers by fire extinguishing powder particles under non-stationary interaction conditions

Pozharnaia bezopasnost` ◽

10.37657/vniipo.pb.2020.101.4.006 ◽

2020 ◽

pp. 63-70

Author(s):

Анатолий Ильич Кицак

Keyword(s):

Inhibition Efficiency ◽

Interaction Time ◽

Maximum Effect ◽

Stationary Mode ◽

Active Centers ◽

Fire Extinguishing ◽

Active Particles ◽

Powder Particles ◽

Stationary Conditions ◽

Inhibition Reaction

Предложена модель механизма гетерогенного ингибирования активных центров пламени частицами огнетушащего порошка общего назначения при нестационарном взаимодействии. Проведена оценка эффективности гетерогенного ингибирования активных центров пламени частицами огнетушащего порошка в нестационарном режиме их взаимодействия. Полученные результаты могут быть использованы для оптимизации условий и режимов подачи огнетушащего порошка в зону горения в целях достижения максимального эффекта тушения пожара. The relevance of the work is due to the need to improve the efficiency of powder fire extinguishing systems. The aim of this work is to evaluate the effectiveness of the mechanism of heterogeneous inhibition of active flame centers by particles of fire extinguishing powder under non-stationary conditions of interaction. It was achieved by the method of theoretical modeling. There are obtained theoretical dependences of the reaction rate of heterogeneous inhibition of active flame centers by fire extinguishing powder particles on their dispersed and dynamic characteristics under non-stationary conditions of active particles interaction with the inhibitor surface. The efficiency of heterogeneous inhibition of active flame centers by fire extinguishing powder particles in a non-stationary mode of their interaction was evaluated. Fire fighting with fire extinguishing powder under non-stationary conditions is more effective the smaller the effective size of powder particles, the effective duration of the inhibition reaction and the longer the interaction time of powder particles with active flame centres. It was established that inhibition efficiency depends either on the kinetic parameters of active centers and disperse characteristics of the powder particles or on the ratio of interaction time of powder particles with the active centers as well as the characteristic duration of inhibition reaction. The results obtained allow optimizing the conditions and modes of fire extinguishing powder supply to the combustion zone in order to achieve the maximum effect of fire extinguishing.

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Oxidation Kinetics of Magnesium Powder Particles in Non-Isothermal Condition

Journal of Advanced Materials In Engineering ◽

10.47176/jame.39.1.21061 ◽

2020 ◽

Vol 39 (1) ◽

Keyword(s):

Oxidation Kinetics ◽

Isothermal Condition ◽

Magnesium Powder ◽

Powder Particles ◽

Kinetics Of

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On a composition of combustion products at a burning of methane-fluorinated hydrocarbon mixtures in air

Pozharnaia bezopasnost` ◽

10.37657/vniipo.pb.2020.43.68.005 ◽

2020 ◽

pp. 44-49

Author(s):

Алексей Юрьевич Шебеко ◽

Юрий Николаевич Шебеко

Keyword(s):

Combustion Products ◽

Hydrocarbon Mixtures ◽

Gaseous Mixtures ◽

Fire Extinguishing ◽

Simplified Method ◽

Room Volume ◽

Composition Of Combustion Products ◽

Fluorinated Hydrocarbons

Выполнена расчетная оценка равновесного состава продуктов горения околостехиометрических смесей вида метан - фторированный углеводород - воздух с использованием как программного комплекса Chemical Workbench, так и предложенной в настоящей работе упрощенной методики. Найдено, что основными продуктами горения являются CO, HO, CO, HF. При этом концентрации прочих продуктов горения имеют существенно более низкие значения. С помощью программного комплекса FDS выполнен расчет динамики концентраций опасных продуктов (СО, HF) в атмосфере модельного помещения объемом 12,6 м. Найдено, что для указанного помещения предельно допустимая концентрация CO достигается через 730 с после начала горения, а HF - практически мгновенно. Результаты работы могут быть полезны при применении фторированных углеводородов для пожаротушения и флегматизации горючих газовых смесей. Calculations of equilibrium compositions of combustion products at burning of near stoichiometric mixtures of methane-fluorinated hydrocarbon-air are presented. The program tool Chemical Workbench was used. Also a Simplified method was proposed. It was found that CO, HO, CO and HF are the main combustion products, and the concentration of other products are much more lower. The results of the calculations of the concentrations of the above mentioned products (CO, HO, CO and HF) by means of the simplified method are close to that obtained by the tool Chemical Workbench ones. The concentrations of CO and HF (the main hazardous products) as a function of time were determined for a typical room volume of 12, 6 m using the program tool FDS 6. It was found that a limiting allowable concentration of CO was reached after 730 s from the burning beginning, but at the case of HF this concentration was reached almost instantaneously. The results of this study can be used at an application of the fluorinated hydrocarbons for fire extinguishing and inertization of flammable gaseous mixtures.

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Kinetik der Reaktion von 2.4-Dinitrofluorbenzol mit Imidazol-, SH- und Imidazol-SH-Verbindungen / Kinetics of the Reaction of 2,4-dinitro-1-fluorobenzene with Imidazole-, SH- and Imidazole-SH-compounds

Zeitschrift für Naturforschung B ◽

10.1515/znb-1971-1011 ◽

1971 ◽

Vol 26 (10) ◽

pp. 1010-1016 ◽

Cited By ~ 2

Author(s):

Renate Voigt ◽

Helmut Wenck ◽

Friedhelm Schneider

Keyword(s):

Temperature Dependence ◽

Rate Constants ◽

Reaction Rate ◽

Ph Dependence ◽

First Order ◽

Molecular Transfer ◽

Thiolate Anion ◽

Nucleophilic Reactivity ◽

Kinetics Of ◽

Lindley Equation

First order rate constants of the reaction of a series of SH-, imidazole- and imidazole/SH-compounds with FDNB as well as their pH- and temperature dependence were determined. Some of the tested imidazole/SH-compounds exhibit a higher nucleophilic reactivity as is expected on the basis of their pKSH-values. This enhanced reactivity is caused by an activation of the SH-groups by a neighbouring imidazole residue. The pH-independent rate constants were calculated using the Lindley equation.The kinetics of DNP-transfer from DNP-imidazole to SH-compounds were investigated. The pH-dependence of the reaction displays a maximum curve. Donor in this reaction is the DNP-imidazolecation and acceptor the thiolate anion.The reaction rate of FDNB with imidazole derivatives is two to three orders of magnitude slower than with SH-compounds.No inter- or intra-molecular transfer of the DNP-residue from sulfure to imidazole takes place.

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Parameters of Plasma and Kinetics of Active Particles in CF4 (CHF3) + Ar Mixtures of a Variable Initial Composition

Russian Microelectronics ◽

10.1134/s1063739718060033 ◽

2018 ◽

Vol 47 (6) ◽

pp. 371-380 ◽

Cited By ~ 4

Author(s):

A. M. Efremov ◽

D. B. Murin ◽

K.-H. Kwon

Keyword(s):

Initial Composition ◽

Active Particles ◽

Kinetics Of

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“Kinetics of molecular transfer across the tegument of protoscoleces and hydatid cysts of Echinococcus granulosus and the relevance of these studies to drug targeting”

Helminth Zoonoses ◽

10.1007/978-94-009-3341-5_6 ◽

1987 ◽

pp. 37-43 ◽

Cited By ~ 2

Author(s):

S. A. Jeffs ◽

H. Hurd ◽

J. T. Allen ◽

C. Arme

Keyword(s):

Echinococcus Granulosus ◽

Drug Targeting ◽

Hydatid Cysts ◽

Molecular Transfer ◽

Kinetics Of

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The Toxicological Testing and Thermal Decomposition of Drive and Transport Belts Made of Thermoplastic Multilayer Polymer Materials

Polymers ◽

10.3390/polym12102232 ◽

2020 ◽

Vol 12 (10) ◽

pp. 2232 ◽

Cited By ~ 3

Author(s):

Piotr Krawiec ◽

Łukasz Warguła ◽

Daniel Małozięć ◽

Piotr Kaczmarzyk ◽

Anna Dziechciarz ◽

...

Keyword(s):

Thermal Decomposition ◽

Degradation Kinetics ◽

Combustion Products ◽

Polymer Materials ◽

Toxic Substances ◽

Butadiene Rubber ◽

Different Temperatures ◽

Increasing Temperature ◽

In Fire ◽

Kinetics Of

The article presents the potential impact of flat drive and transport belts on people’s safety during a fire. The analysis distinguished belts made of classically used fabric–rubber composite materials reinforced with cord and currently used multilayer polymer composites. Moreover, the products’ multilayers during the thermal decomposition and combustion can be a source of emissions for unpredictable and toxic substances with different concentrations and compositions. In the evaluation of the compared belts, a testing methodology was used to determine the toxicometric indicators (WLC50SM) on the basis of which it was possible to determine the toxicity of thermal decomposition and combustion products in agreement with the standards in force in several countries of the EU and Russia. The analysis was carried out on the basis of the registration of emissions of chemical compounds during the thermal decomposition and combustion of polymer materials at three different temperatures. Moreover, the degradation kinetics of the polymeric belts by using the thermogravimetric (TGA) technique was evaluated. Test results have shown that products of thermal decomposition resulting from the neoprene (NE22), leder leder (LL2), thermoplastic connection (TC), and extra high top cower (XH) belts can be characterized as moderately toxic or toxic. Their toxicity significantly increases with the increasing temperature of thermal decomposition or combustion, especially above 450 °C. The results showed that the belts made of several layers of polyamide can be considered the least toxic in fire conditions. The TGA results showed that NBR/PA/PA/NBR belt made with two layers of polyamide and the acrylonitrile–butadiene rubber has the highest thermal stability in comparison to other belts.

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Effect of chloride ions on the kinetics of nitrobenzene reduction by powdered iron

Chemical Papers ◽

10.2478/s11696-006-0065-1 ◽

2006 ◽

Vol 60 (5) ◽

Cited By ~ 2

Author(s):

M. Heželová ◽

L’. Pikna ◽

D. Kladeková ◽

L. Lux

Keyword(s):

Specific Surface ◽

Reaction System ◽

Particulate Material ◽

Surface Reactivity ◽

Chloride Ions ◽

Free Medium ◽

Iron Particles ◽

Nitrobenzene Reduction ◽

Powder Particles ◽

Kinetics Of

AbstractThe effect of different chloride ions concentrations on the reactivity of iron particles was studied using chronopotentiometry. It was found that the increase of Cl− ions concentration accelerated anodic dissolution of iron, thus enhancing its surface reactivity. This fact was confirmed also by the rate of nitrobenzene reduction by iron particles. The reactivity of powder particles of various sizes, hence of different specific surface, was investigated in chloride-free and chloride-containing acetate buffer electrolytes. Experimental results indicated that the rate of nitrobenzene reduction in the presence of chloride ions in the reaction system is faster in comparison with the rate in chloride-free medium for each studied grain fraction of particulate material.

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