Search

The description of the device and principle of operation of the continuous muffle furnace for hot briquetting of chip‑powder dispersions of ferrous metals is given. A distinctive feature of this device is the presence of two systems of gas‑flame and induction heating, as a result of which the achievement of the specified charge heating temperature is guaranteed with the complete removal of the liquid phase. The oil component of the coolant is used to create a protective hydrocarbon atmosphere that provides non‑oxidizing heating of the metal, as well as to obtain a carbon coating, which, in addition to protective functions, acts as a lubricant in the hot briquetting process. Subsequent combustion of oil vapors in the furnace leads to significant savings in natural gas. A furnace built according to this principle has the smallest dimensions and the highest technical and economic characteristics.The simulation of the chip heating process in the zone of loading into the furnace is carried out. The dependences of the temperature of the chips at the outlet of the screw feeder on the temperature of the flue gases at the inlet for the mass fraction of coolant in the chips of 10 % and various fractions of oil are obtained. It has been established that during the heating of the chips in the loading zone, phase transformations of the coolant do not occur, the charge heating temperature does not exceed 100 °C.

The methane-hydrogen fraction is a gaseous hydrocarbon by-product during oil processing for obtaining petroleum products. Until recently, the methane-hydrogen fraction was used as furnace oil in internal technological processes at a refinery. Some of the low-calorie methane-hydrogen fraction was burned in flares. Driven by the prospect of the methane-hydrogen fraction use as a fuel alternative to natural gas for burning in thermal power plants boilers, it became necessary to study the methane-hydrogen fraction combustion processes in large volumes. The conversion of ON-1000/1 and ON-1000/2 furnaces from the combustion of the methane- hydrogen fraction with combustion heat of 25.45 MJ/m3 to the combustion of the composition with combustion heat of 18.8 MJ/m3 leads to a decrease in temperature in the flame core for 100 °C as an average. The intensity of flame radiation on the radiant tubes decreases. Therefore, the operation of furnaces during combustion of methane-hydrogen fraction with a low heat of combustion at the gas oil hydro-treating unit is carried out only with a fresh catalyst, which allows lower flame temperatures in the burner.The experiments to determine the concentration of nitrogen oxides NOx and the burning rate w of the methane-hydrogen fraction in the ON-1000/1 furnace and natural gas in the TGM-84A boiler, depending upon the heat of combustion Qnr were carried out. The obtained results showed that the increase in the hydrogen content Н2 from 10.05 % to 18.36% (by mass) results in an increase in the burning rate w by 45%. The burning rate of natural gas with methane CH4 content of 98.89% in the TGM-84A boiler is 0.84 m/s, i.e. it is 2.5 times lower than the burning rate of the methane- hydrogen fraction with H2 content of 10.05%. The distributions of heat flux from the flame qf over the burner height h in the TGM-84A boiler were obtained in case of natural gas burning and calculation of burning of the methane-hydrogen fraction with a hydrogen content of 10.05% and methane of 28.27%. The comparison of the obtained data shows that burning of methane- hydrogen fraction causes an increase in the incident heat flux qf at the outlet of the burner.

The paper examines conditions for the ignition of high fire point combustible liquids on extended surface materials (e.g. textiles or insulating materials) prone to the so-called «wick effect». It is demonstrated that such liquids may ignite at lower temperatures than their standard fire points. The «wick effect» has to be taken into account when determining the nature of the liquid used to set fire to a person and/or property. The implications of this effect for the spontaneous combustion of liquids and meltable solid organic substances on porous materials is also discussed.ERRATUMAn error was discovered in the article. The reference to GOST R 51355-99 on page 47 was incorrect and should have read as follows: Alekseyev S.G., Barbin N.M., Avdeyev A.S., Pishchal’nikov A.V. Explosion and Fire Hazards of Vodka. Fire and Explosion Safety. 2009, vol. 18, No 2, pp. 20–23. The error was corrected on April 6, 2018.

Some relations between various auto- and soliton models are investigated. Common features in the problem formulation of combustion, supersonic radiation wave propagation and moving of soliton wave on soundings are revealed. Realization of the known mathematical solutions for wave flame structure characterization in the reciprocating motor grain is proved.

The relevance of the research. When simulating the combustion processes it is often necessary to determine the temperature field. Traditional methods of experimental studies of combustion processes involve the use of a large number of thermocouples to determine the temperature fields in the flame, which causes difficulties in determining the temperature. The thermocouple determines the temperature not in a specific point of the space, but in a region with radius about ten diameters of a thermocouple. When using the thermo" couple method, one should consider the inertia feature and heat flow over the free ends. Modern methods of infrared diagnostics with application of thermal imaging cameras allow abandoning the use of a large number of thermocouples and obtaining the acceptable spatial resolution with high time details. The methods used in the study: The paper deals with the experimental study of temperature change in the flame. The flame genera" ted at combustion of different fuels was selected as the test object. The combustion was shot with a thermal imaging camera in different spectral ranges. At the same time, the temperature in the flame was controlled with a thermocouple; the emissivity was corrected by the data from the thermocouple. On the thermogram obtained the authors have selected 20 points on the same vertical axis. For each point the array of temperatures was obtained. The fast Fourier transform was applied to the array. The authors obtained the frequency" amplitude spectra of temperature change. The results. The typical temperature surges were identified. To investigate liquid fuels the frequency maximums are ranged from 4 to 16 Hz, for vegetative combustible materials the frequency peaks were found in the range from 2 to 7 Hz.

The feasibility of using ionization sensor for the investigation and diagnosis of the fuel combustion process in piston power plants with spark ignition is substantiated. It is shown that in order to expand the functions and increase the reliability of operation and signal processing accuracy of the ionization sensor it is necessary to know the impact of the flame fluctuating velocity on the latter. Based on the analysis of published data and in-house research a mechanism of the effect of fluctuation velocity on the electrical conductivity of hydrocarbon flame is proposed, estimated by the value of ion current. A formula for calculating the ion current is proposed, which includes the fluctuation velocity, the flame temperature and the concentration of carbon particles in the fuel. For methane-air flame, it was revealed that for U' 8 m/s an increase of ion current is observed, which is due to increased flame temperature and concentration of carbonaceous fuel particles in the zone of chemical reactions of the flame. When U' 8 m/s the ion current decreases due to the growth of heat consumption for heating the incoming fuel in the flame front, directly proportional to the fluctuation velocity. The results can be used to predict and monitor characteristics of turbulence in the combustion chambers of power plants with the aid of the ionization sensor.

The use of ionization sensors for the study and diagnosis of the combustion process in gas-turbine power plants is substantiated in the paper. The review of literature data and in-house research show that thermionic emission of electrons from incandescent carbon particles plays a decisive role in the mechanism of ionization of flame sprayed in a stream of liquid hydrocarbon fuels. It is shown that as liquid fuel is injected into the circulation area of a bluff body the area of maximum concentration of electrons that determine the conduction current is located in the circulation area. When liquid fuel is injected in the flame holder the zone of maximum electron density is located in the zone between the recirculation mixing zone and the slipstream. It was found experimentally that the distance between the region of maximum electron density and the stabilizer base is determined by the quantity of the fuel sprayed, the initial temperature, the flow turbulence and the gas flow rate. The results can be used to predict and monitor the characteristics of turbulent flame in combustion chambers of power plants with the help of ionization sensors. They also make it possible to create a system of continuous monitoring and control of ignition and combustion processes ensuring minimum concentration of toxic emissions in the exhaust combustion products.

The paper presents a list of plant products prone to microbiological self-heating and spontaneous combustion. It examines the conditions and indicators of the emergence and development of these processes in hay and peat. An example from forensic casework describes fire in a haystack resulting from its microbiological spontaneous combustion. It is demonstrated that the “hay clinker” effect may arise both from spontaneous combustion and from an act of arson; therefore, it cannot be used as a differentiating feature of arson. Equations are proposed for the prediction of conditions leading to thermal self-ignition of hay and peat, with examples of calculations. The paper includes previously published data on the emission of heat by various materials at 20 °С, and their aeration, as well as data needed for the analysis of the causes of hay or peat fire resulting from their microbiological self-ignition.

The flame stability with regard to one-dimensional exponential perturbations both for the combustion in the fire-chamber and the flame propagating in closed tubes or chambers is investigated. It is proved that both stability and instability are possible for the combustion process. At the same time the one-dimensional flame instability is guaranteed near the front wall of the fire-chamber where the fuel supply is realized. Therefore the control of combustion in the fire-chamber leads to support of the flame at the maximum possible distance from the front wall of the fire-chamber to prevent the vibratory combustion or to diminish intensity of pulsations if these pulsations are inevitable.

The flame stability with regard to two-dimensional exponential perturbations both for the combustion in the half-open fire-chamber and the flame propagating in half-open channels is investigated. It is proved that only instability ispossible for the combustion process. At the same time the one-dimensional flame instability is guaranteed near the front wall of the fire-chamber where the fuel supply is realized. Possibilities for the control of combustion in the halfopenfire-chamber and diminishing of intensity of pulsations are discussed.

Some relations between various auto- and soliton models are investigated. Common features in the problem formulation of combustion, supersonic radiation wave propagation and moving of soliton wave on soundings are revealed. Realization of the known mathematical solutions for wave flame structure characterization in the reciprocating motor grain is proved.

Macroscopic laws of sprayed hydraulic fluids (fresh water and water with salt admixture) evaporation when moving through the fixed height flame has been studied by the experiment using high-speed measuring system. The integral parameters of drop evaporation (size, mass, concentration) were determined. The authors found out the conditions of spraying the test hydraulic fluids ensuring the completeness of their evaporation.

Leonov's works are analyzed from the point of view of symbols and semantics of fire. "Fire" occurs in the writer's texts very frequently and he uses the words which are to a certain degree related to this noun. Leonov uses the word "fire" and its synonyms literally and figuratively. Very often these images are interrelated and create parallels (putting out the fire is to be understood as death of a person). The theme of "dying fire" in Leonov's works is not only associated with such individual characters as Ablaev and Vadim Loskutov from Pyramid but it has a deeper relation to the fate of the humankind (the last novel focuses on the "great final", which might acquire the form of nuclear Apocalypses, "Prometheus' fire" in which everybody burns). Metaphorical image of fire is tied to dramatic changes undergoing in Russia after the October Revolution (20-30-ies): by many characters, Russia is comprehended as a fierce fire. The metaphor "fire of mind", which is closely connected with Prometheus, has been widely acknowledged. This metaphor hides the genius of creation, the talent of "fire bearer" Skutarevski (in Skutarevski) as well as ambivalence of scientific gains (Shamin from the novel Pyramid speaks about them) which threaten with the catastrophe leading to self destruction. Another metaphor occurring in Leonov's works is "inner fire". This metaphor implies intense sufferings experienced by Vekshin (The Thief) and Gelasij (Soviet River), dedication to others - Skutarevski, Vichrov (Russian Forest), the fire of wishes - Julia Bambalski (Pyramid) and the fire of passion - Semion and Nastia (Badgers). Hence, the fire in Leonov's fiction manifests in different forms: as destroying or sanctifying element, as a symbol of dramatic changes in post revolutionary Russia, as a symbol of creative power, genius of a man, talent, sufferings leading to rebirth, love passion, commitment to other people or ideas. The images, themes and associations of fire supplement the epoch and characters' features and at the same time Leonov's system of images prevents from abusing the "Prometheus fire". [ABSTRACT FROM AUTHOR]