Burning of mixtures of magnesium with sodium nitrate. I. Burning velocity of two-component mixtures of magnesium with sodium nitrate

We propose a physically sound model for burning of mixtures of magnesium with sodium nitrate and we obtain an equation determining the burning velocity of such mixtures. We analyze the effect of various factors on their burning velocities. We compare the calculated and experimental dependences of the burning velocity on the ratio of components, the magnesium particle size, the initial temperature of the mixture, and the external pressure. Scientific Research Institute of Applied Chemistry, Sergiev Posad 141300. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 5, pp. 40–49, September–October, 1994.     

Combustion characteristics of a hydroxylammonium nitrate based liquid propellant. Combustion mechanism and application to thrusters

A new composition of hydroxylammonium nitrate based solution containing ammonium nitrate, methanol, and water was developed for monopropellant in a reaction control system (RCS) as an alternative to conventional hydrazine. In comparison with hydrazine, this solution has a 20% higher specific impulse, 1.4 times higher density, and lower freezing point and toxicity. The linear burning rate of the solution is moderate at the operating pressures of RCS thrusters. It was found that the linear burning rate had some characteristics whose mechanisms had not been understood. The combustion mechanism of this solution was investigated. The burning behavior was observed using a medium speed camera, and a temperature profile for the combustion wave was measured with a 2.5 μm diameter thermocouple. From these results, the instability of the liquid-gas interface may trigger a sudden increase in the burning rate, and methanol was found to be effective in reducing the bubble growth rate in the solution. The reactivity of several catalysts was evaluated in an open-cup test, and the S405 catalyst for hydrazine showed the best performance among them. Thruster tests were conducted using the S405 catalyst with variation in the propellant mass flow rate, catalyst bed configuration, and length-to-diameter ratio of the combustor. As a result, parameters were determined that ensured long operating time. The model thruster operated stably for up to 100 sec with a specific impulse I _sp = 240 sec, which corresponds to a 90% efficiency. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 4, pp. 109–120, July–August, 2009. An erratum to this article can be found at     

氧取代羟胺盐的合成研究进展

综述了氧取代羟胺盐的几种合成方法,并对其前景做了展望.     

Combustion of magnesium-sodium nitrate mixtures. II. Burning rates of three-component magnesium-sodium nitrate-organic fuel mixtures

A limiting scheme of the combustion of three-component magnesium-sodium nitrate-organic fuel mixtures is suggested. An approximate equation for determining the burning rates of these mixtures is proposed. The experimental and calculated dependences of the burning rate on mixture composition and external pressure are compared.Scientific-Research Institute of Applied Chemistry, Sergiev Posad 141300. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 6, pp. 75–78, November–December, 1994.     

Comparative study of failure mechanisms of MoSi2 coating on Mo1 wire mesh under isothermal oxidation and hot-fire test using a hydroxylammonium nitrate based monopropellant

A MoSi₂ coating was prepared on the Mo1 wire mesh via pack cementation method, and its failure mechanisms under isothermal oxidation and hot-fire test using a hydroxylammonium nitrate based monopropellant were comparatively studied. Under isothermal oxidation at 1300 °C and 1400 °C, degradation of MoSi₂ into Mo₅Si₃ caused failure of the coating, and interdiffusion made a much larger effect relative to oxidation. However, the MoSi₂ coating failed because of the synergy of oxidation, ablation, and interdiffusion under hot-fire test. Besides, dissolution of mullite into SiO₂ and ablation of high velocity flame contributed to the failure of the coating as well.     

Burning characteristics of materials

The feasibility of using a dynamic, i.e. multivariable, test procedure instead of the more usual single point tests has been investigated by determining the limiting conditions for burning. The rate of burning and the limiting conditions for flaming and smoldering combustion have been determined over a range of temperatures and oxygen concentrations. Results show that the relative burning rates of materials and also their relative combustion thresholds can alter significantly with changes in the tests environment.     

燃烧的激情

每年在黑岩沙漠里都会有一个狂欢季。所有参与者聚集一起燃烧一个高达12米的木制人形雕像,把Burning Man推向高潮。     

加热炉炉管的烧焦

介绍了小型炼油厂常压蒸馏装置加热炉炉管的烧焦方法,指出了烧焦过程中的注意事项。     

Burning of the Carbonized Polymers

Abstract

The paper discusses the influence of the carbonized layer and the effect of its separate characteristics upon polymer combustibility. The expressions relating burning rate with carbonized layer thickness and some properties of degradation products are presented and main directions of lowering carbonized materials combustion have been shown. They are to increase viscosity of pyrolysis products and to decrease coke penetrability.     

洁净燃烧技术的应用

石油化工管式加热铲排放的尾气是大气污染的主要污染源之一，从燃料燃烧角度出发，分析了几种主要污染物的生成机理及燃料燃烧的影响因素，介绍了洁净燃烧设备的特点及应用情况，指出添加燃料添加剂、控制好燃烧工况及选用洁净燃烧设备能有效降低甚至脱除尾气中的污染物，达到洁净燃烧的目的。     

Correlating Aluminum Burning Times

Characteristics of aluminum combustion are summarized in an overview of the subject, focusing on the burning time of individual particles. Combustion data from over ten different sources with almost 400 datum points have been cataloged and correlated. Available models have also been used to evaluate combustion trends with key environmental parameters. The fundamental concepts that control aluminum combustion are discussed, starting from a discussion of the D ⁿ law. The exponent in the D ⁿ law is shown to be lower than two, with nominal values of ≈1.5 to 1.8 being typical. The effect of the ambient medium on the burning time is considered, oxygen as an oxidizer being twice as effective as water and about five times more effective than carbon dioxide. The effect of pressure and initial temperature is minor. __________ Translated from Fizika Goreniya i Vzryva, Vol. 41, No. 5, pp. 55–69, September–October, 2005.     

Burning Behaviour of ADN Formulations

The application of ADN for an effective oxidizer of propellants and explosives requires a detailed knowledge of the burning behaviour. The physical and chemical mechanisms of the combustion depend on pressure. Especially profiles of temperature and species in the flame are important to design propellant formulation of high performance and low signature of the rocket plume. In the presented study, pure ADN and ADN/paraffin mixtures were investigated as strands in an optical bomb at pressures of 0.5 MPa to 10 MPa. The application of non-intrusive combustion diagnostics for the investigation of fast burning energetic materials allowed the measurement of burning rates and profiles of temperature and gas components at various distances above the burning propellant surface. The burning rate was determined by using a video system and a special frame analysis. The acquisition and analysis of emission spectra in the UV/VIS allowed the investigation of rotational temperatures, the determination of particle temperatures and the identification of transient flame radicals. The vibrational temperatures of final combustion products resulted from band spectra emitted in the near and mid infrared spectral range. Burning rates of 5 mm/s to 70 mm/s were recorded showing a mesa/plateau-effect in the pressure range of 4 MPa to 7 MPa. The UV/VIS spectra indicated an emission from OH, NH and CN radicals. The strong emission of OH bands of the ADN/paraffin mixture allowed the investigation of rotational temperatures with a mean value of 2700 K which is closely below the adiabatic flame temperature of 2950 K. Additionally, one-dimensional intensity profiles of the flame radicals were measured. As combustion end products H₂O, CO, CO₂ and NO were found. NO could only be detected at a distance up to 2 mm above the propellant surface. The measured CO/CO₂ fraction was higher as 10/1. Water could only be detected far above the propellant surface.     

废弃塑料燃烧动力学

采用热重法对6种废弃塑料的燃烧过程进行了实验研究,计算了它们的燃烧反应动力学参数.结果表明,所用样品燃烧过程以多段式为主,活化能在38.2～488.1kJ/mol之间.可以预计,废弃塑料在冶金炉内可以迅速燃烧.     

富氧燃烧技术的应用

介绍富氧燃烧在燃油玻璃窑炉上的应用及改进经验     

The electrochemical reduction of nitrate in acidic nitrate solutions

Cathodic regeneration of nitrous acid by electrochemical reduction of nitrates could yield a catholyte which is useful in the processing of manganiferous ores. The purpose of the present investigations was to study the cathodic reaction in an electrolytic cell with an acidic nitrate electrolyte. Electrochemical reduction of nitrate has been investigated in the ranges 0.45–2.70m H+, 0.0–0.1m HNO2, 0.5–2.0m NO3– and 20–80°C at several cathode materials. Potentiodynamic scanning experiments with a platinized titanium cathode showed limiting current densities of 0–300Am–2 at cathode potentials of +950–+700mV vs SHE. At cathode potentials less than +700mV vs SHE, cathodic reduction of nitrous acid to nitric oxide took place. A linear relation between the nitrous acid concentration and the limiting current density was found in this experimental range. Nitrous acid can be produced by cathodic reduction of nitric acid in a membrane cell. However, the maximum concentration of nitrous acid that can be produced is limited by two reactions; decay of nitrous acid to nitric acid and nitric oxide and cathodic reduction of nitrous acid to nitric oxide.     

含快燃物改性双基推进剂燃速模型的建立

建立了含4种不同晶形快燃物(立方体、球形、长方体、片状)无烟改性双基推进剂的燃烧数学模型,推导出推进剂燃速数学表达式,以及在推进剂燃烧方向上快燃物有效使用粒径的数学表达式。运用建立的数学模型分别计算了含5％和7％快燃物ACP的某推进剂在不同压强下的燃速,计算结果与实测燃速基本吻合。     

Burning of pools of electrical-insulating oils

The spread of flame from a wick across pools of two electrical-insulating oils and the subsequent burning of the pools have been studied in the presence and absence of flame retardants added to the oils. The time required for the flame to spread across the pool, the ensuing rate of burning of the complete flame, and the composition of the burnt gases have been measured with no additive present. The times required for the flame to spread have been compared with between zero and a range 0.2 to 20% by volume of halogen-containing inhibitors present. The times required for flame spread with the untreated oils are governed by the interaction of heat transfer from the wick flame to the pool, the growth of convection currents in the pool, and the resultant evaporation of the more volatile fractions of the oil from the surface of the pool. The relative efficiency of the additives, CH₂I₂ >CH₂Br₂ >CCI₄ >CICHCCI₂, suggests that in the mechanism of inhibition the more efficient act as chemical inhibitors.