Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Eine Plattform für die Wissenschaft: Bauingenieurwesen, Architektur und Urbanistik
Non-Stationary Ventilation Conditions with Open Mine Fires
Open mine fires lead to the occurrence, in non-horizontal ventilation roads, of a driving effect, which for ascensional ventilation leads to an increase, and for descensional ventilation to a decrease, in the amount of ventilation. From this it follows that with descensional ventilation one can speak of an opposing effect. An appropriate magnitude of the opposing effect can cause a ventilation reversal. From the safety point of view the case of a mine fire with descensional ventilation is of the most interest, as it can lead to the greatest effects on the ventilation in the whole mine network. The consequences of open mine fires with descensional ventilation have, as opposed to ascensional ventilation, a specific time relationship, which arises from the dynamics of the fire as well as from the ventilation in the whole mining network: (1) The first phase involves the condition from the beginning up to the stopping of the ventilation flow. In this time period the opposing drive increases to a given value, which depends on the intensity of the fire. (2) After this, follows a condition of equilibrium in which the ventilation flow is either zero, oscillates about this value, or, rather quickly, a ventilation reversal occurs. This condition is to be treated as a typical unstable equilibrium state of the ventilation and fire processes. A disturbance must exceed a given value in order to bring the dynamic system out of the unstable equilibrium condition and lead to a stable ventilation reversal. (3) The third phase involves the time period after the stable ventilation reversal. This condition depends only on the magnitude of the opposing drive. As we can see from the above considerations, an assessment of the change of condition resulting from open mine fires, with descensional ventilation, is very difficult. (ERA citation 10:004262)
Non-Stationary Ventilation Conditions with Open Mine Fires
Open mine fires lead to the occurrence, in non-horizontal ventilation roads, of a driving effect, which for ascensional ventilation leads to an increase, and for descensional ventilation to a decrease, in the amount of ventilation. From this it follows that with descensional ventilation one can speak of an opposing effect. An appropriate magnitude of the opposing effect can cause a ventilation reversal. From the safety point of view the case of a mine fire with descensional ventilation is of the most interest, as it can lead to the greatest effects on the ventilation in the whole mine network. The consequences of open mine fires with descensional ventilation have, as opposed to ascensional ventilation, a specific time relationship, which arises from the dynamics of the fire as well as from the ventilation in the whole mining network: (1) The first phase involves the condition from the beginning up to the stopping of the ventilation flow. In this time period the opposing drive increases to a given value, which depends on the intensity of the fire. (2) After this, follows a condition of equilibrium in which the ventilation flow is either zero, oscillates about this value, or, rather quickly, a ventilation reversal occurs. This condition is to be treated as a typical unstable equilibrium state of the ventilation and fire processes. A disturbance must exceed a given value in order to bring the dynamic system out of the unstable equilibrium condition and lead to a stable ventilation reversal. (3) The third phase involves the time period after the stable ventilation reversal. This condition depends only on the magnitude of the opposing drive. As we can see from the above considerations, an assessment of the change of condition resulting from open mine fires, with descensional ventilation, is very difficult. (ERA citation 10:004262)
Non-Stationary Ventilation Conditions with Open Mine Fires
W. Trutwin (Autor:in)
1977
7 pages
Report
Keine Angabe
Englisch
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