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Purposes and problems of the student work
Conclusions and future research
Investigation of ventilation airflow stability in workings with descending and ascending airing under the conditions of Scheglovskaya mine is the purpose of master’s work.
Main points of this paper:
— computing of normal and emergency air distribution;
— prospective air flow turnover localization (changing of air traveling direction in working);
— marking of all workings thick with fire gases (gas zone);
— air stability estimation of workings at fires;
— elaboration of measures to increase air stability of workings.
Estimation and support of workings ventilation stability will be carried out on mines of Ukraine as consisted with “Design guide of coal mines ventilation”, ”Safety rules of coal mines”. Designation of mine ventilation stability is performed in accordance with [1] :
— on final stage of constructional design by engineering company after adoption of ventilation specific scheme, calculation of it’s characteristics, settings of regulators and calculation of air distribution;
— on the basis of the execution calculation of air-distribution by unit of SMMRD on the production of the depression and gas surveys jointly with the ventilation and safety division (VSD) at working out of measures on providing of normal mine ventilation on all characteristic periods of expansions, including lead in of every new longwall face, to the next survey;
— by empirically the ventilation and safety divisions at the lead in of new long wall faces in service and after addition of major modifications in ventilation scheme as compared to position, SMMRD accepted at a calculation . The stability rating is thus performed mainly only to that part of scheme a change happened in which, and also branches stability of which from the indicated changes goes down.
Mine ventilation diagrams falls into three divisions on degree of stability.
First. Diagrams with high degree of stability. Among these are networks wherein changing of air flow in long wall faces of working area not exceeded 20%, and by booster fan suction – 10% from expected, ventilation systems without diagonals, as also networks with diagonals, ventilation stream turnover wherein practically next to impossible even at emergency modes.
Second. Diagrams with average degree of stability. Ventilation systems with changing of air flow range within: for long wall faces and working areas 20-25%, by booster fan suction 10-30% from expected, ventilation systems with diagonals, ventilation stream turnover wherein is possible at emergency modes are belong to given category.
Third. Diagrams with low degree of stability. Changing of air flow in long wall faces and working areas more than 50%, by booster fan suction more than 30% from expected, ventilation stream turnover is possible by normal mode are belong to given category.
The mine ventilation diagrams must have a degree of stability not below than 2th category.
Basic data for the stability calculation are ventilation connections, aerodynamic resistance, air flows and their direction in branches, parameters of natural ventilating pressure.
The depression survey used as a base for the receiving of basic data. In those cases, when no information on the several workings available, they can be got by calculation in accordance with law as consisted with [1].
It is enough to produce the stability analysis for one definitive branch, rendering most influence on stream stability in working – diagonals and having broad range of changing aerodynamic resistance. Determining branches are ventilation losses through strakes, and in absentia of last-mentioned - branch, dangerous by increase of aerodynamic resistance and directly joining to the working-diagonal on an return stream ( after a fray out).
The execution calculation of stability is exercised on an computer. The program of stability calculation foresees definition of stability index Kr by the calculation of air coursing in a network at a zero air flow in the examined diagonal, achievable due to the automatic change of determining branch resistance . The value Kr remaining on this resistance is compared to the value of maximally possible change of aerodynamic resistance of this branch. If value of stability index (KR) more maximally possible change of resistance a determining branch, stream turnover in a diagonal is deemed to be practically impossible and inversely.
The assessment of resistance first conducted with the use of four different determination methods of path resistance shorting:
— resistance decrease of typy branches in 100 times;
— determination of resistance the way of shorting as amount of working resistance and doorway resistance;
— use the value of middle resistance of shorting way, which is 0,69;
— resistance calculation of shorting ways, on a formula for a air-passage.
On the basis of the results got during master's degree work comparison will be conducted and a conclusion is done about what from the above-stated methods is most exact.
In degree paper on the computer model of mine the Scheglovskaya-deep is produced estimation of stability of vent streams in working with descending and ascending ventilation for normal and emergency modes (task> emergency> assessment of resistance descending-ascending ventilation). Workings were identify in which turnover of a ventilation stream happened and measures are adopted on the increase of ventilation stability in these workings by ventilation devices.
Red — emergency workings
Yellow — zone of the spreading fireman gas before turnover ventilation stream
Blue — zone of the spreading fireman gas after turnover ventilation stream
Presently in degree paper researches of workings ventilation stability are conducted with descending and ascending ventilation at fires and measures are created on the stability increase . The routes of people show out will be formed from longwall face and influence of stream shorting will be analyze on ventilation stability using four methods of decisions of shorting way in future.
Red — emergency workings
Yellow — zone of the spreading fireman gas before turnover ventilation stream
Crimson — route of the conclusion miner from gsa zone