Hazards Analysis of LPG Pipeline Transportation. Dr. A. Yedigarov, Research Institute of Natural Gases & Gas Technology 142717, Russia, Moskovskaya obl., Leninsky raion, p. Razvilka, VNIIGAS, Fax: 7-095-399-16-77
Preliminary results of risk assessment of LPG main pipeline under
design are presented. The study is devoted to computer simulations
of liquefied petroleum gas (LPG) accidental releases, evaporation,
vapour cloud propagation and dispersion for a number of different
accident scenarios including hypothetical ones -- complete rupture
of the main pipeline. As it is well known, the most dangerous
accidents at LPG facilities are accompanied by the formation and
evolution of the dense vapour clouds. The explosive or toxic
cloud can travel over a long distance producing large hazardous
zone and severe consequences. To solve this problem. the original
three-dimensional hydrodynamic numerical model was used for simulation
of the turbulent flow and explosive vapour cloud evolution in
the atmospheric boundary layer. The model is based on numerical
integration of a complete set of unsteady non-linear Navier-Stokes
equations of mass, momentum and energy balances within the scope
of algebraic turbulent viscosity submodel. The following accident
scenarios were examined: complete or partial rupture of the pipeline
without pumping shut-down, stop pumping in a certain period of
time (after leakage identification) and isolation of the pipeline
damaged section by means of shut-off valves. Computations made
it clear that the maximum hazardous zone and probable consequences
depend to a great extent not only on the atmospheric stability
state and wind speed but also on the time required for the accident
identification and decision making. The performed numerical study
also demonstrates the advantages and possibilities of mathematical
modelling (accident imitations) in risk management issues for
correct reproduction of variable emergency situations on the LPG
pipeline, elaboration of protective measures for consequences
limitation and checking their efficiency.