Relevance
The economic transformation in Ukraine and other countries of the former Soviet Union have led to serious problems in the field of safety of technological facilities, dangerous concerning explosion and fire. In the 90th years the gap of economic ties between the suppliers of components and equipment manufacturers, as well as companies that exploit it, the outflow of qualified professionals with industry, and the deterioration of industrial discipline led to an increase in the number of industrial accidents and disasters. Each year on average for CIS countries as a result of accidents and disasters killed more than 330 thousand people. That in 4,7 times more than it was in the former USSR [1]. Depreciation of equipment in many industrial enterprises and fixed assets in Ukraine today varies 60%, which is considered a critical point, after which the number of accidents and disasters may increase like an avalanche.
This information indicates that the task of ensuring explosion safety in industrial plants has not been studied and resolved. Therefore, the problem, associated with forecasting the likelihood of explosions in the factories and the development of organizational and technical measures to prevent the relevant scientific problems, are actual and solution of this problems is in the interest of economy of Ukraine.
Main Part
The premises with is dangerous concerning explosions and fires are equipped with the systems of gas protection and emergency ventilation. When the concentration of air-gas-mix is critical, the signal from gas protection automatically submits on system of inclusion the emergency ventilation. Then, the signal from gas protection stops the equipment which has lost tightness, or disables the technological line or even manufacture as a whole [1].
The circuit of an explosive chamber can be represented as: Fig. 1
Fig. 1 – The circuit of an explosive chamber (the given image is an animation with following in parameters: quantity of the staff - 11, quantity of cycles of recurrence - 4, volume in Kb - 352)
1 – electric equipment; 2 – probable places of outflow of gas (technological installations); 3 – gauges of gas protection; 4 – The basic ventilation; 5 – emergency ventilation.
The explosion of air-gas-mix in these premises is possible if the three casual events will coincide in space and time: occurrence of an explosive air-gas mix in a premise; refusal of gas protection; occurrence of short circuit in a cable.
On basis Markov casual processes has been developed the mathematical model. This model allows to predict a level of explosion safety of premises, which are dangerous concerning explosions and fires, and to receive the following dependence: probability of occurrence of explosion during time t from frequency and duration of occurrence of an air-gas-mix dangerous concerning explosion, reliability of system of gas protection and terms of its preventive maintenance, and from frequency and duration of occurrence of arc short circuits in a cable.
For the case when: λ1 << μ1; λ2 << μ2; λ3 << μ3 and λ3θ < 0.1 the formula for definition of intensity of explosions in premises will become:
1/λ1 - average interval from time between occurrences of the short circuit in the protected network;
1/μ1 - average duration of existence of arc short circuit;
1/λ2 - average interval of time between occurrences of the high concentration of air-gas-mix;
1/μ2 - average duration of existence dangerous concerning explosion concentration of gas mixture;
1/λ3 - average interval of time between refusals of system of gas protection;
θ - average interval of time between the preventive maintenance of systems of gas protection.
The probability of explosions eventually in shop can be estimated with the help of the formula:
F(t)=1-e-H*t (2)
The received dependence allows to choose optimum from the point of view of safety term of preventive maintenance of system of gas protection that allows to provide a normalized level of explosion safety of premises, i.e.
F(8760)<1.14*10-6 (3)
Conclusion
On the basis of Markov random processes was proposed mathematical model "environment-defense-source".Using the developed mathematical model was obtained dependence of the probability of an explosion in the premises, dangerous concerning explosions and fires, from the frequency and duration gas-outflow, the reliability of the emergency ventilation and timing of her diagnosis, as well as to the frequency of occurrence of a dangerous electrical source.
Resulting in dependence allows you to choose the timing of diagnosis of the emergency ventilation, which provides standardized level of explosion safety, as well as to improve the accuracy of calculations by more than an order of magnitude, compared with known patterns.
Literature
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