Abstract
Contents
- Introduction
- Relevance of the topic
- Analysis of recent research and development on
- The objectives and tasks in the master's work
- The research results
- Conclusion
- List of sources
Introduction
In the mines of Ukraine annually register up to several tens of endogenous fires. They remain stable in the second place, after exogenous fires, the magnitude of damage. He reached 12 to 40% of the losses caused by coal mining accidents. In recent years, endogenous fires were put out of operation in the field of excavation pits them. AF Zasyadko, "Privolnyanskaya" them. VM Bazhanov, "Krasnoarmejskaja Zapadnaja» № 1, "Krassnolimanskaya", "Bulavin," and others.
Underground fires occur in remote locations, such as the fixing space, or worked out in the pillars in coal deposits of insulating ridges in the seams-satellites. Suppression of combustion sources in such circumstances is difficult, due to what is the highest duration of the elimination of this type of underground accidents.
Existing methods and means to prevent ignition of coal are based on outdated notions of self-heating natural multiphase medium in mines, is not considered a number of features of upper-air and geomechanical processes developed in the coal-bearing strata. Despite the rapid development in recent years of forecasting methods and technologies for prevention of spontaneous combustion of coal and rocks of coal deposits, remains an urgent task to improve the arsenal of means and ways to prevent endogenous fires in mines. The centers of self-heating and spontaneous combustion of coal in recent years have increasingly found in places of intersection of the elaboration of preparatory areas of geological formations violations. However, the reasons for the origin of heat sources in an oxygen-free environment is not clarified until the end.
There are several views on the nature and mechanism of self-heating of seats: low-temperature oxidation, the action of thiobacilli, a combination of geomechanical and upper-air and other factors. The analysis showed that at different stages of evolution of the centers of self-heating of coal is possible prevalence of one of the causes or groups of factors, but not reliably established that is the root, giving rise to the intense increase in temperature and the emergence of self-heating chamber.
There is a need to improve the arsenal of means and ways to prevent fires in underground mines. Particularly relevant in a crisis situation for the coal industry is to develop a so-called common technical measures to reduce the fire hazard of mine workings due to the choice of rational methods and technological conditions of the process of coal extraction.
In this regard, the disclosure of the conditions of emergence and development of centers of self-heating and combustion of coal, development of tools and methods for their prevention and suppression in hard coal-bearing strata under development, is an urgent scientific and technical problem whose solution will ensure efficient and safe mining.
Relevance of the topic
Despite the intensive development of the means and methods of elimination of ground accidents, there remains the problem of improving the actual technology of rescue work in mines, natural gas, especially when severe and long-term tactical measures.
Technology eliminate the sources, causes and consequences of severe accidents associated with high risks of injury to rescuers effects of a gas-air mixture explosion (WAN), poisoning by toxic products of combustion, the action of high temperatures, a collapse of rock.
According to the State Militarized Rescue Service (GVGSS) annually in the mines of Ukraine are at least four explosions of methane-air mixture, causing the victim, often numerous. Sometimes the explosions are the result of complications of these types of accidents, as the gas content mines, fires, especially endogenous, sudden emissions of coal, gas, and sandstones. Statistics show that the greatest number of injuries that occur in mines, is the result of explosions littered with mines, moving burning in remote places (in the goaf, Locking space, crushed pillars).
However, the development of Ukrainian scientists and development of industrial production of membrane gas distribution systems offers the prospect of heavy high-performance remote elimination of ground accidents. However, the lack of appropriate modern means of technology hinders progress in the field of fire protection of coal mines. It is obvious that the improvement of fire-fighting technologies must not be accompanied by a decrease in the level of security rescuers.
In connection with vishenapisannym, studies to assess and mitigate risk rescue operations, the establishment of the regularities of formation of explosion-proof gas environment in the area of emergency operations, ensuring the remote execution of the basic technological operations by means of control and automation is an important scientific and technical challenge.
Analysis of recent research and development on
Especially difficult is fire occurring in remote places of the spontaneous combustion fires interacting with the air of coal [1],[2]. The immediate impact of such conditions on the hearth burning fire extinguishing means, it is usually impossible because of the difficulty of penetration to the center of the combustion, the threat of complications such accidents, smoke, zagazirovaniem, and often bursts pylegazovozdushnyh mixtures of rock collapse in production, instability modes of ventilation and elevated temperatures in the field of emergency works. Due to inaccessibility and non-intensive air infiltration is inefficient use of water, foam, powder and other rescue equipment located on the parts of fire extinguishers.
One of the most promising ways to prevent, contain and extinguish fires in coal mines is a disaster area Inerting the atmosphere, which is defined as an artificial decrease in the concentration of oxygen in the atmosphere of mines by feeding it flegmatiziruyuschego combustion gas [2],[3]. Most often, nowadays, use nitrogen gas, although there are technologies of carbon dioxide gas mixture. Purging with nitrogen gas can solve the following problems during the liquidation of an underground fire: reduce the period of liquidation of the accident, to prevent explosions of gas-air mixture at the emergency site; accelerate the cooling of high-temperature zone to a safe level, localized or completely stop the burning process.
To ensure the rational mode purging air volume in the isolated mining the authors proposed to use the energy of the flow of inert gas supplied from the installation of the membrane [4],[5]. For this purpose, the development of erecting an additional insulating jumper, and the pipeline for the supply of nitrogen makes the branch, through which gas is supplied into the space (chamber) between the two ridges (Fig. 1).
In Fig.1 –Technological scheme of nitrogen supply in an emergency mine workings: 1 – vozduhopodayuschaya development, 2, 3 – Insulating jumper number 1 and number 2, respectively, 4 – line 5 – fitting, 6, 7 – valves, 8 – gauge.
When the chamber is filled with nitrogen, feed it through a branch regulated so as to equalize the pressure in the development of the incoming fresh air stream and between the bridges. In this situation, there are no air leaks through the jumper into the camera. Differential pressure is redistributed to the development of the site, divided by an additional bridge, on either side of which is nitrogen, it is the same substance leaks. Thus, elevated to the development of additional vozduhopodayuschey jumpers and supply of nitrogen is achieved by replacing it leaks air leakage of nitrogen and, therefore, excluded air leaks in the isolated output. It is possible to develop ways to extinguish underground fires [2],[5], to allow for more effective elimination of the accident, taking into account the features of membrane systems.
However, when you close the openings in the jumpers increases depression, applied to an isolated volume and flow of methane increases sharply from the worked-out area and surrounding development of fractured gas-containing rocks. In addition, during the period of filling the chamber with inert gas continues to leak air through the sealed area of the body jumpers and cracks in the surrounding rock mass, which results when mixed with methane to form an explosive mixture. Because desensitization gas mixture is carried out by the inert gas from the gas separation membrane installation, productivity is much less air leakage during filling of the chamber between the ridges with an inert gas, this leads to an increase in the duration of the period of formation of a mixture with low oxygen content, resulting in a significant amount can be filled explosive mixture. Thus, despite the increase in quenching efficiency of underground fires as a result of the proposed methods [2] suschestvuvet threat of an explosion in an isolated volume of mining due to the considerable duration of the period of formation of non-hazardous gas mixture with low oxygen content. This greatly reduces the environmental and economic effectiveness of the proposed methods of extinguishing underground fires have evolved in remote places.
The objectives and tasks in the master's work
The objective of this research is to improve the way fire evolved underground fires in remote locations to ensure the safety of the work to prevent and extinguish combustion sources in the mines by reducing the period of transition from a gas environment with a dangerous concentration of combustible components in an inert atmosphere and to avoid creating an explosive methane-air mixture.
The research results
The authors proposed a method of preventing and extinguishing pockets of combustion in underground mines. In the first stage in the development of a mountain at the same time erecting bridges 5, place a few elastic shells 9, one end of which the clamp is tightened, 8 and fill them with inert gas from line 2 of the gasification installation through the tube for feeding an inert gas 3, setting the flow rate through the flow regulator inert gas 4 (Fig. 2a). The volume elasticity of shells shall be not less than the volume of mining at the site of the jumpers to isolate the source of combustion. Then, after the construction of three bridges fitting cover, connect the flexible membrane 9 proemnoy pipe 7 by means of the clamp 8, and the inert gas is fed to the sealed area to the fire burning six simultaneous installation of gas supply pipeline 2 and the flexible membrane 9 (Fig. 2b). Regulation of depression carried out at the main dam with an inert gas flow regulator 4.
a
b
In Fig. 2 – Method of preventing and extinguishing pockets of combustion in underground mines: 1 – Development, 2 – pipe for introducing the inert gas from gasification installations, 3 – outlet for supplying an inert gas, 4 – controls flow of inert gas, 5 – isolating the main and additional bridges to hole 6 – burning fireplace, 7 – proemnaya pipe insulation jumpers, 8 – clamp, 9 – elastic shell.
Conclusion
Thus, by placing in the mines a few extra elastic shells filled with an inert gas, it is possible to increase the supply of inert gas in an isolated space and reach a solution of the problem of security of the work in the prevention and suppression of fires in underground mines by reducing the period of transition from air with a dangerous concentration of combustible components in an inert atmosphere in an isolated area of mine workings. At the same time reducing the elimination of the accident leads to a reduction of greenhouse and toxic gases into the environment, as well as to reduce the cost of doing emergency work, and therefore increases the ecological and economic effectiveness of new methods of fighting evolved underground fires in remote places.
б
Fig 3 –Method of preventing and extinguishing pockets of combustion in underground mines
List of sources
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