Dissertation for receiving the master's degree "M.Sc."
Treatment: Process Engineering
Abstract
In this research, a quantitative assessment of the risk caused by process accidents , such as leakage of process equipment, including flanges and valves, which may occur in the gas pressure boosting station of Ramsar city, has been investigated. This evaluation has been modeled by PHAST software according to the collected information such as (pressure of the substance in the process, temperature of the substance in the process, phase of the substance in the process, composition per cent of substances in the process, weather conditions, prevailing wind direction, type of scenario, location of the scenario, location, population distribution, etc.). In this project, an attempt is made to determine the scope of the effect of these events by modeling two possible types of fire in the Ramsar gas pressure boosting station, which are sudden fire and explosive fire caused by leakage of flanges and valves investigated in the defined scenarios, and by drawing related diagrams. Also, by entering data related to risk determination such as population distribution, spark occurrence location, spark probability, accident repeatability and so on. The contour diagram of individual risk and the probability of casualties in different modeled ranges as well as the F-N diagram of collective risk can be obtained. By having the F-N diagram of collective risk related to the station, it can be compared with the standards of other countries and determine the level of riskiness of the system as well as appropriate solutions to control and reduce these incidents and their consequences. Keywords: Quantitative risk assessment - Eruption fire - Sudden fire - Individual risk - Collective risk - Consequence assessment
Introduction [1] and [2]
Living in a safe and risk-free world has always been the desire of humans, and attention to safety has existed as an effort to survive in the human institution since the beginning of creation. On the other hand, human beings have always been trying to improve their life and level of well-being, and in this way, by making changes in nature, they have tried to use its resources. Industrial activities are part of human efforts to achieve greater prosperity, but as a result of these changes and the expansion of these types of activities, certain risks have occurred due to changes in the common system of nature. With the passage of time and the growth of industrial activities, the risks related to them have also grown. Therefore, in order to have a safe environment, today, having risk-free industries is a big concern for the general public and especially experts and industrialists. On the other hand, today's scale of production and the amount of investment, which has increased significantly compared to the past, requires the existence of safer units. Because in the event of an accident, the amount of damages will be very high and this is unbearable for today's industry, which is ruled by ruthless competition. The proximity of industrial units to densely populated centers has increased the economic and social effects of accidents. In the early years of the expansion of industrial activities, safety engineering was manifested in the form of learning from accidents to improve its designs. Based on the experiences gained and to prevent similar incidents, the engineers compiled and published their learning process in the form of design codes. Due to the limited scope of industrial activities at this time, accidents are generally limited to specific equipment or ultimately the boundaries of the factory, but after the rapid growth of the chemical and oil and gas industries, at the beginning of the sixties, the number and scope of the impact of industrial accidents also increased significantly. 1974 or the toxic gas leak incident in Soso 2, Italy in 1976 are only examples of these incidents. These incidents and incidents of this kind, unlike the incidents before the sixties, had an impact beyond the borders of the respective factories. It was at this time that due to the strong pressure of public opinion, the safety laws of industrial units were approved by the European community.In the United States, after the Bhopal 3 disaster in India in 1984, which is still known as the most heinous incident in the chemical industry after many years, and some accidents that have occurred in this country, several laws in the field of industrial safety were passed by Congress. According to the need felt in the last years of the sixties, methods for identifying process risks, such as the well-known "quantitative risk assessment" method, were invented and presented. Therefore, to reduce the scope or probability of these incidents, there is a need to implement methods known as risk management. The purpose of risk management is to evaluate and then eliminate or control the risk centers. Today, risk management is used not only in the chemical and oil and gas industries, but also in many organized human processes such as economic activities or huge construction projects.
-1. The main purpose of the research
The purpose of this project is to evaluate some dangerous accidents that are likely to occur at the Ramsar 1 gas pressure boosting station, and also to examine the effects and consequences of these accidents, with experimental data and modeling by PHAST software, and finally, appropriate solutions and suggestions will be provided to control and reduce the consequences of these accidents.
1–2. Statement of the problem
Today's need of human societies to define compliance with higher standards, in dealing with activities related to process industries, is always increasing. These standards are generally aimed at increasing the safety level of process industries. Fulfilling this need creates a conflict between the profit from the expansion of process units and the risk on people and equipment. The definition of these standards, on the one hand, has led to the change of the process, the bulking of industrial units and the change of conditions outside
1- Ramsar Gas Compressor Station
the borders of industrial units, and on the other hand, it causes the production risk to change by industrial units. According to current trends, this change is generally increasing. Therefore, determining and observing the appropriate distance between the sources of risk and the vulnerable sector always creates the necessary flexibility in dealing with possible changes over time. Determining these distances and related studies is done through a method called quantitative risk assessment or QRA method. Quantitative risk assessment is a method that can provide an appropriate estimate of safe distances according to the set of existing conditions and taking into account the probability of accidents. In the quantitative assessment of the risk of accidents, two parameters play a major role. The first parameter is the consequence and the second parameter is the repeatability of the incident. Consequence means the amount of damage caused to the system due to a single incident and repeatability means the number of times that incident occurs in a one-year period. Generally, none of these two parameters alone are sufficient to assess the risks. For this reason, determining a criterion that takes into account both factors is very useful in assessing risks. Subordination of risk from repeatability and consequence is complex in most cases and according to the methods used for risk assessment, various combinations of them are presented. But in the simplest case, risk can be considered the product of small amounts of consequence in repeatability.
Abstract :
In this research, we have studied quantitative risk analysis (QRA) arising from process incidents like the leakage of process equipments, including flanges and valves which may be occurred in gas compressor station in Ramsar, Iran. This analysis has been modeled in PHAST software computer program according to data such as the pressure, the temperature, the phase and the composition of the material in the process, weather conditions, dominant wind, type of scenario, scenario occurrence site, positioning, population distribution and etc. Flash fire and jet fire resulting from flanges leakage are two kinds of probable fire in gas compressor station in Ramsar. This project is an attempt to determine the domain of these events effect by modeling the above mentioned fires in studied flanges of defined scenario and drawing its relevant diagrams.