Dispersion of several common 'heavy' gases (ethylene, propylene, ammonia, a
nd chlorine) has been modelled on the basis of modifications in plume path
theory. The model takes into account, among other things, the variations in
temperature, density, and specific heat during the movement of the heavy g
as plume. The effects of wind speed, density of the gas, and venting speed
on the plume dispersion have been simulated. Based on the simulations a set
of empirical equations has been developed. The equations have been validat
ed by theoretical as well as experimental studies.
Studies have also been carried out to simulate the effect of venting speed
(manipulated by injecting hot air with the released gas) on the plume dispe
rsion. The study reveals that the effect of venting speed on dispersion is
very pronounced and can be used to reduce the risk posed by the accidental
luxurious release of toxic/flammable gases. For example an increase of 20%
in venting speed of chlorine (54.1 m/s) can reduce the distance up to which
toxic concentration would occur by about 1100 meters. (C) 1999 Elsevier Sc
ience Ltd. All rights reserved.