Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2023
Thesis Language: Turkish
Student: Öznur YILMAZ
Supervisor: Fatma Suna Balcı
Abstract:
Process means any activity involving chemical(s), including the use, storage, production, handling, or transport of chemicals on site, or any combination of these activities. Inadequate precautions and fault made during the operation of processes cause accidents in the processes. Process safety focuses on prevention and mitigation of catastrophic releases of chemicals or energy. Apart from catastrophic releases, there are also releases of chemicals into the environment during the operation of process due to the nature of process. In order to prevent ATEX (Atmosphere Explosive) accidents caused by ignition sources in the explosive environment created by the release of flammable chemicals under normal operating conditions, it is necessary to carry out hazardous distance determination studies and take precautions in these hazardous areas. There are numbers of standard approach (60079-10 1, CEI 31–35, etc.) and softwares (PHAST, ALOHA, etc.) for hazardous distance determination. While there are deficiencies and limitations for liquid behaviour in standards, there may be limitations in software for intervention in modelling. Especially for flammable chemicals liquefied under pressure, the post-release behaviour varies significantly depending on the nature of chemical and this affects the size of hazardous distance over which the chemical is emitted. This facts cause doubt in the results calculated from standards or software. In order to investigate the validification of the limitations of standards and assumptions in softwares and eliminating the doubts, a model using energy, mass, and heat conservation equations depending on the physicochemical properties of the chemical has been developed. For the comparation of the model results with the ones obtained with standards and softwares, a geothermal plant where isopentane, a flammable chemical, is widely used, was proposed, and scenarios of isopentane release in liquid phase at high pressure and temperature through two different sized openings were studied for the summer and winter conditions. According to the worst case scenario, it was found that the hazardous distances obtained from standards (except for the 2% evaporation calculation) were higher than the ones obtained from other methods, while it was lower in the ALOHA software. It was observed that the results of PHAST and the developed model are similar.
Key Words
: Process safety, ATEX, 60079-10-1, PHAST, ALOHA