Predicting consequences in the event of fire and spillage of hazardous chemicals

V diplomskem delu smo modelirali izlitje vodne raztopine amonijaka in posledice tega dogodka. Analizirali smo masni pretok izhlapevanja sedmih raztopin, ki so podane v računalniškem orodju Evaporation Calculator. Največji pretok smo ugotovili pri vodni raztopini amonijaka, zato smo v programu ALOHA modelirali izpust te kemikalije. Največji vpliv na izhlapevanje amonijaka in tvorbo plinastega oblaka imajo hitrost vetra, temperatura zraka, stabilnost in vlažnost ozračja. Pri modeliranju smo izbrali opcijo izračuna toksičnega oblaka nevarnega plina in sistem mejnih vrednosti AEGL. Rezultati modeliranja izlitja amonijevega hidroksida podnevi so pokazali, da bi bili v smrtni nevarnosti vsi, ki bi bili od točke izpusta oddaljeni manj kot 107 metrov ob 60 minutni izpostavljenosti. Tisti, ki bi bili od točke izpusta oddaljeni manj kot 291 metrov, bi lahko občutili dolgotrajne škodljive učinke na zdravje. Rezultati izlitja amonijevega hidroksida ponoči pri 60 minutni izpostavljenosti so pokazali, da bi bila območja nevarnosti večja kot podnevi. Glede nevarnosti požara smo ugotovili, da bi bilo območje nevarnosti za vnetljivost doseženo samo pri modeliranem scenariju v nočnih razmerah. V primeru požara v bližini rezervoarja z amonijevih hidroksidom je potencialno mogoča eksplozija BLEVE, a je malo verjetna. Med ukrepi ob izrednem dogodku razlitja sta najpomembnejša ustavitev izhlapevanja amonijaka in evakuacija zaposlenih.The diploma thesis models the spillage of aqueous ammonia solution and the consequences of this event. The mass flow rate of evaporation of the seven solutions given in the Evaporation Calculator tool was analysed. The highest flow rate was found in aqueous ammonia solution, so we modelled the release of this chemical in the ALOHA program. The most significant influence on the evaporation of ammonia and the formation of a gaseous cloud is provide by the speed of wind, air temperature, its stability and humidity. At modelling, we chose the option of calculating the toxic cloud of dangerous gas and the AEGL limit values system. The results of a simulation of an ammonium hydroxide spill during the day showed that anyone who is less than 107 meters away from the discharge point would be in mortal danger after 60 minutes of exposure. Those who are less than 291 meters away from the point of discharge could experience long-term adverse health effects. The results of an ammonium hydroxide spill and 60-minute exposure at night showed that the danger areas would be larger than during the day. With regard to the fire hazard, we have concluded that the flammability hazard level would have only be reached in the simulated scenario in night conditions. In case of a fire near an ammonium hydroxide tank, a BLEVE explosion is possible, but unlikely. Among the measures at the event of a spill, the most important ones are the containment of the ammonia evaporation and the evacuation of the employees