Русский   Український
DonNTU   Masters’ portal

Abstract

Сontent

  1. Goals and objectives of the master’s work
  2. Theme urgency
  3. Scientific and technical novelty
  4. A summary of the master’s work

    4.1. Brief characteristics of the mine

    4.2. Development of a computer model of a mine ventilation network

    4.3. Features of formation of natural draft in the mine

  5. Conclusion
  6. List of sources

1. Goals and objectives of the master’s work

The purpose of the master’s work is to study the stability of ventilation by natural draft.

Tasks which are decided in the master’s work:

  • Development of a computer model of a mine mine ventilation network Toretskoy;
  • Study on the influence of natural draft ventilation mine in normal conditions;
  • Investigation of the influence of natural draft ventilation at the mine after the main fan stops (zero mode);
  • Study on the influence of natural draft ventilation mine in the reverse mode;
  • Develop recommendations to ensure the sustainability ventilation of of mine workings.

2. Theme urgency

Steep fall in the mines major influence on stability of ventilation provides natural draft. Natural draft mine may act in one direction with the fan or counteract its work. When co-directional action of natural draft and main fan air flow in the mine increases and vice versa. The main part of the natural draft in modern of deep (600 m) mines of Donbass is formed in mine trunks. In mines with steeply dipping bedding of layers in winter natural draft in the contours of trunks may be 1000–1300 Pa in the contours excavation plots of 70–80 Pa.

Natural draft in the contours of excavation plots has great influence on the mode of their airing. For example, on some central district of Donbass mines after stopping the main fan air flow working areas are reduced by 30-40%. This means that the main influence on the ventilation sections provides natural draft in the contours of excavation plots and trunks.

Practice reversing planned ventilation shows that in most cases because of opposition from of natural draft, excavation plots are not provided with necessary air flow (60% Qn in compliance with safety regulations) [7].

In some cases, the air flow in the lavas capsizes. In addition, there is a danger that an emergency stop of the fan main ventilation by natural draft in the trunk circuits can occur rollover air leaks between the trunks and outgoing jet air supply falls into the trunk. Most likely to occur such a situation in the summer, when natural draf in the upper ventilation trunks circuit becomes negative. In such cases there is a danger recirculation Incoming and high concentration of methane in the air supply trunks.

For the negative effects of natural draft should also include delay rollover air flow in mine workings. In mines with an angle of occurrence of layers of more than 16° when reversing delay tipping can be 15–30min. This is due to the redistribution of temperature in the workings with fresh and outgoing stream.

3. Scientific and technical novelty

During execution the master’s work for the first time in the mine Toretskoy GP Dzerzhinskugol investigate the influence natural draft on the distribution of air in mine workings and its impact on the stability of ventilation, as well as the first time be celebrated the reversing modeling and zero modes.

4. A summary of the master’s work

4.1. Brief characteristics of the mine

The Field of mine Toretskoy is located in the northeastern part of the city of Dzerzhinsk, Central Donbass mining region.

The size of the mine field along the strike of 3.5–4.5 km, the area of the mine field of 13.4 km2. The angle of incidence varies from 20–44°. Category mine gas – over categorical. Mine field opened by two vertical trunks number 1 and number 2, the horizontal capital crosscuts. Scheme mine ventilation – central, method of ventilation – suction. Airing of mine carried main ventilation installation located at the skip trunk number 2, equipped with two fans WCD-47U, work and backup. Fresh air enters the mine on the trunk number 1 from the following lavas and other objects airing forwarded to skip trunk number 2 and is issued to the surface.

4.2. Development of a computer model of a mine ventilation network

Program complex IRS Ventilation mine – EPLA is used to investigate the factors influencing the ventilation of mines and development recommendations for improving the ventilation of mine workings in normal and emergency conditions. With this program is presented existing scheme mine ventilation Toretskaya as a sequentially of interconnected branches and nodes (fig. 1).

Figure 1  – Computer model of mine <q>Toretskaya</q> in the program complex<q> IRS Ventilation mine - EPLA</q></p>

Figure 1 – Computer model of mine Toretskaya in the program complex IRS Ventilation mine – EPLA

Normal functioning of the model, the database was created, which includes 112 air nodes and 164 branches. As well as the Enter data such as length of production, the cross section, the slope, spot elevations, etc. Marked in yellow rooms nodes, and blue – branch numbers.

Figure 2  – Computer model of mine <q>Toretskaya</q> to the imposition of node numbers

Figure 2  – Computer model of mine Toretskaya to the imposition of node numbers

Figure 3  – Computer model of mine <q>Toretskaya</q> to the imposition of branch numbers

Figure 3  – Computer model of mine Toretskaya to the imposition of branch numbers

4.3. Features of formation of natural draft in the mine

Natural draft arises as a consequence of different densities of air in mines. As depression of the fan, its magnitude measured in Pascals.

Depression of natural draft depends primarily on the depth of mine and the differential temperature of air in an air supply and air supply workings. Since the air temperature at the surface is not constant, then observed daily and annual changes in the natural draft. Depending on the nature of changes in the natural draft of coal mines can be divided into the following groups:

1. Small (up to 100 m depth), the value of the natural draft of which is small and usually not exceeds 20–30 Pa. direction of action natural draft on such mines may vary even within one day. After stopping VGP air velocity in mountain workings of decreases 8–10 times or more. Its maximum value is observed both in the cold and in the warm season.

2. Average depth (100–500 m) in which the direction of natural draft may vary throughout the year. Its maximum value observed during the cold season. During this period of time after stopping VGP air velocity decreases in mines typically 2–4 times.

3. Deep (depth of over 500 m), in which natural draft mine is always positive, ie, throughout the year helps VGP work. The maximum value of the natural draft in such mines is also observed in the cold season. During this period, Stop VGP may lead to a slight change in air velocity. In some experimentation fixed change rate is only 20–30%.

The main factor determining the magnitude of the natural draft in the cold season in the mines of the second and especially the third group, is the depth of the mine. First, this is due to the fact that the temperature of the air entering the mine varies within narrow repartitions due to its heating. Secondly, the temperature of outgoing jet is determined mainly by the temperature of the host rocks, which increases with the depth of the mine.

Based on the results of treatment of depression of filming carried out in coal mines, the following dependence for evaluation maximum possible value of natural draft, Pa [1].

pic4

z – mine depth, m.

Dependence should be regarded as indicative, since it takes no account of other factors (air distribution in the network, time of year, etc.).

Calculation depression natural draft may be made by hydrostatic or hydrodynamic methods. when choosing a ventilation modes are recommended dynamic process which has clarity and allows more accurate consider the influence of the natural contour rods. The method consists in the following. Selected route that matches the direction of air movement and passing through the emergency section and one of the clearing faces. This route is planned number of characteristic points, coinciding with the beginnings and ends of developments. If the difference in elevation between the start and end any production of more than 100 m, it outlines the intermediate points, trailing from each other vertically by 50–100 m. At each point, the route is measured air temperature. Then computed using of mine surveying data distance from the horizontal plane passing over the mouth trunk to each item. From the data obtained is building diagram Air temperature changes along the selected route (fig. 4). When it was built on the horizontal axis air temperature, and the vertical – depth.

Figure 4  – Diagrams determining the value of natural draft mine <q>Toretskaya</q>

Figure 4 – Diagrams determining the value of natural draft mine Toretskaya

Natural draft charts and proportional to the area defined by the formula [1]:

pic6

ρср  – the average density of the air in the workings;

S – area diagrams;

tц  – temperature center of gravity of the diagrams.

After calculations of the natural draft of the above formula in trunks and working areas, it is necessary simulate. In the computer model IRS Ventilation shafts – EPLA natural draft is modeled by adding depression in-branch production. It uses a special insert Extras depression in the window of each branch [3, 4]. Additional Depression is introduced into an inclined (vertical) production with a rising air stream if one generation Descending, and the other – Ascending ventilation.

Simulation showed that the natural draft air flow increased by 20–30%.

Моделирование пожара в ветви 46 компьютерной модели шахты <q>Торецкая</q>

Figure 5 – Simulation of a fire in the branch number 46 computer model mine Toretskoy
(animation: 7 frames, 5 cycles of repetition, 60 kilobytes)
(Gray – the original state; yellow – the zone of distribution of fire gases to rollover air flow; blue – zone spread of fire gases after rollover air flow; Red – branch wherein a fire occurs)

Conclusion

At this stage in the master’s work developed a computer model of mine ventilation network using software ensure IRS Ventilation – EPLA.Simulated mine ventilation network considering natural draft trunks and circuits excavation plots and the influence of its ventilation on the mine as a whole, as well as excavation plots. In the future, will modeled zero and reverse modes ventilation mine. The result of the recommendations will be made to ensure sustainability of mining ventilation, as well as safe working conditions in the normal and reverse modes ventilation.

List of sources

  1. Болбат И. Е., Лебедев В. И., Трофимов В. А. Аварийные вентиляционные режимы в угольных шахтах – М.: Недра, 1992 г., – 204 с.
  2. Булгаков Ю. Ф., Трофимов В. О., Кавєра О. Л., Харьковий М. В. Аерологія шахтних вентиляційних мереж – Донецьк, ДонНТУ. – 2009. – 88 с.
  3. Каледіна І. О., Романченко С. Б., Трофимов В. О. Комп’ютерне моделювання шахтних вентиляційних мереж: Методичні вказівки. – М.: Видавництво МГГУ. – 2004. – 72 с.
  4. В. О. Трофимов, Ю. Ф. Булгаков, О. Л. Кавєра, Є. Б. Ніколаєв. Комп’ютерне моделювання аварійних вентиляційних режимів / навчальний посібник / Донецьк, Норд-Пресс. 2013.
  5. Медведев Б. И., Гущин А. М. и др. Естественная тяга глубоких шахт. – М.: Недра, 1985. – 77 с.
  6. Рекомендації по вибору ефективних режимів провітрювання шахт при аваріях // НДIГРС. – Донецьк. – 1995 г., – 165 с.
  7. Правила безопасности в угольных шахтах. – К. – 2010. – 422 с.