JOSRA 4 - 2015

11.01.2016
Článek se zabývá bezpečností bioplynových stanic. V úvodní části je představena situace a počty bioplynových stanic ve vybraných státech Evropy. Následně jsou popsána nebezpečí a obecné scénáře havárií, které na těchto zařízeních mohou nastat, a také příklady skutečných havárií, které se na bioplynových stanicích v České republice a v zahraničí již udály. Znalost nebezpečí a poučení se z havárií na obdobných zařízeních jsou důležitým předpokladem ke spolehlivému a bezpečnému provozu každé technologie.
11.01.2016
Large quantity of models for pool fire characteristics is available in the literature. In the present work, we implemented different possibilities of heat fraction calculation and we introduced the flame length in order to calculate the point source-target distance. Finally we do not consider the atmospheric stability as constant but we introduced simple mathematical correlation and compare both the model with and without this parameter. The present contribution shows that the Effects model and presented model are almost same based on the heat flux calculation results and therefore that the implementation of the Yellow book model is well done. Nevertheless, from an area of the pool of approximately 5000 m2 there are differences between both models. Those differences are evaluated about 10%. Moreover, it is interesting to evaluate the pool fire behavior according to the nature of the fuel. For the same scenario that is say for the same ambient condition and mass of fuel the variation of the heat of flux as a function to the area of the pool for benzene, gasoline and methanol were shown. The methanol burning is characterized by flame which is not enough visible. We can conclude that more the soot is present when a fuel burn more the heat of flux is affected.
11.01.2016
Gas mixture explosions and fires are responsible for most of the largest property loss events worldwide in the chemical and power industry. In this contribution, a theoretical analysis was performed of explosion behavior for CO/O2/N2, CO/O2/N2/H2O and CO/O2/N2/CO2 mixtures. Presented explosions based on real scenarios of accidents associated with transport and storage facilities with flammable chemicals. While explosions of pure flammable chemicals are well described in the literature, the information about explosions of toxic flammable substances is rather scarce. This work aims at studying the explosion behavior of pure mixture and of the inerted carbon monoxide-air mixtures at different initial temperatures and pressures. The results of mathematical modeling of the calculated maximum explosion pressure are presented.
11.01.2016
Renewable energies became more and more important in the last years. The production of biogas using agricultural waste and the use of wind and solar energy in combination with water electrolysis is one way to substitute natural gas. Therefore the number of syngas plants is growing very fast. On the other hand, the operation of such plants could be responsible for a significant number of accidents. The main focuses of this contribution are the explosion characteristics and hazards arising from the biogas. Primarily, these are the hazards of fire and explosion induced by flammable components of syngas. However, further hazards are the dangers of asphyxiation and poisoning by gases such as carbon monooxide. These hazards will be the aim of the following article. In order to prevent explosions when storing and handling syngas it is necessary to know the explosion limits of individual gas components and its gas mixtures in mixture with air. However, syngas from gasification unit can vary significantly in its composition. Therefore, for each gas composition the explosion limits would have to be determined. This would require a considerable amount of time and effort. Due to this fact, the explosion limits of syngas are frequently referred to only by the hydrogen fraction of the gas mixture in the safety-relevant literature. In reality as syngas consists of hydrogen, methane, carbon monoxide, carbon dioxide and further residual gases the explosion limits are generally over or underestimated.
11.01.2016
A theoretical study on maximum explosion pressure is presented. The maximum explosion pressures, computed by assuming chemical equilibrium within the explosion front are examined in comparison with the measured explosion pressures. Comparisons of the experimentally measured pressures with the calculated adiabatic pressures indicate the degree of adiabacity of the explosion. The calculated peak explosion pressures of hydrogen-air mixtures for ambient conditions are examined in comparison with the experimental values and with the calculated adiabatic explosion pressures. In the present contribution we calculated the maximum pressure for hydrogen-air mixtures in a spherical closed volume at different initial temperatures up to 200 °C. The results represents a continuation of numerous efforts by various research groups, where the key underlying problem has been the understanding of results obtained in laboratory tests for predicting the consequences of gas explosion scenarios in industry.

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