Dispersion of dense gas / Dispersão de gases densos na atmosfera

AUTOR(ES)
DATA DE PUBLICAÇÃO

2004

RESUMO

This work describes significant alterations in the computer code, DENZ, which is applied to the study of the consequences of accidentally releasing large quantities of heavy, i.e. havier than air, toxic or flammable gases to the atmosphere. lt also contains a discussion of the reasons why the study of such substances is necessary and describes the characteristic features of their behaviour. With this alterations it is possible to run the computer code in a microcomputer PC, including the additionals graphical facilities as well as friendly interface. The most interesting characteristic of the dispersion of such type of gas is the phenomenon of gravitational driven slumping. This important feature can lead to the rapid formation of toxic clouds which may affect people standing close to the release or even upwind. The second and important feature of dense gas dispersion considered is that, once slumping is terminated, the action of atmospheric turbulence dilutes the cloud in such a way that the rate of growth of the cloud height is considerably smaller than that expected for a passive plume. This means that the entrainment of air is suppressed in the presence of a density gradient. As the cloud is diluted and becomes warmer, due to heat transfer with the surrounding, its density approaches that of the surrounding air. lt becomes increasingly like a passive gas, and, in due course may be treated as a ?conventional? plume using standard models of atmospheric dispersion. The predictions allow the understanding of the dispersion phenomenon on dense gases and represent a powerfull tool to take decisions as well as can be employed in personnel training in factory emergency situations

ASSUNTO(S)

gas dispersão ammonia risk analysis dispersion avaliação de riscos amonia

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