Sharif Digital Repository

Plant layout and siting are the earliest steps in any process design that may have significant effects on the further required level of safety and costs. Extensive carried out studies have been published in literatures in which, the safety factor has been taken into account in the form of prediction the severity of likely accidents. Majority of these studies are based on the accident consequence and other important parameters such as the accident frequency and the density of vulnerable items have been ignored. This recent negligence may lead to over conservative designs. To eliminate this recent deficiency, quantitative risk assessment (QRA) is the best procedure than can be suggested.... 

Release of toxic gases and hazardous materials is very dangerous for health of people that presence in near of release places. Whereas if the concentration of some toxic materials is more than a definite limit, it may cause of irreparable hurt to health of people in very short times, hence reduce the concentration of released materials can get the time for refuge in safe sites for people that presence in released site in initial times.
In this paper with use the Computational Fluid Dynamics models the effect of fence in reduce the concentration of dense gases and delay the distribution of these gases has been studied. The two toxic gas (chlorine and methyl-isocyanate ) have been... 

Sour Gas is more dangerous than sweet gas because of its hydrogen sulfide contents. So it requires more safety considerations. In this project, the effect of wall thickness and design factor of pipeline on the safe distance was examined by using risk assessment method. The safe distance tables for 4 pipelines with different wall thicknesses and design factors were prepared based on operating pressure, pipe diameter and hydrogen sulfide concentration in gas by using PHAST and PHAST RISK softwares. In this project, the depth of cover parameter was considered in safe distance determination. Also the leak of sour gas was simulated by using... 

In this project, ammonia dispersion in the environment have been investigated and the experimental data have been used in order to show accuracy of calculations. Also, the results of CFD have been compared with the results of PHAST software. The results show that when there is no obstacle in the way of gas release, dispersion models will get good results, but due to existence of the obstacle, their error will be increased to 300%. However, the error resulting from CFD is less than 24% even if there are obstacle there. The effects of obstacle’s distance and height on the dispersion of ammonia gas are investigated. This study showed that the concentration of ammonia increase, when the distance... 

One of the most important stages to designing a process plant is layout of equipment in unit area. There are plenty of routine procedures to find out equipment arrangement and their separation distances based on process and cost criteria. Although some studies have been carried out to enter safety parameters to conventional procedures, the problem complexity because of the number of involved equipment is still of concern. To clear these ambiguities, the new approach presented in this thesis is aimed at quantifying the effects of adjacent equipment on each other. In this way, fire radiation and explosion have been selected as the major hazard that any equipment can expose on the other items,... 

Among probable hazards in chemical industries: vapor cloud explosion (VCE) is one of the worst and most destructive ones. More than half of the major process inci¬dents, according to the statistics, are VCEs. VCE causes the most serious consequences; therefore, it attracts many attentions to itself. Accordingly, plenty of researches have been done for the purpose of protection against VCE effects. All efforts in this field can be categorized in two different main activities; firstly, prescribing safety distances between groups of hazardous equipment and vulnerable areas, secondly, using facilities which reinforce vulnerable areas against explosion blasts. Regardless to which category is... 

Asphaltenedeposition is a major problem during natural depletion and EOR processes due to formation damage issues. It is necessary to reveal asphaltene deposition mechanisms and its effective parameters to prepare an acceptable prevention strategy. Therefore, different natural depletion and EOR experiments must performed on core samples. In this research, Effect of CO2 injection on asphaltene deposition phenomena has been surveyed. Two carbonate core samples and one sandstone core sample was used in experiments. The oil used in these experiments was recombinedoilfrom one of Iranian offshore oilfield.In order to estimate permeability reduction during experiment, injection of oil and CO2 was... 

Chlorine is used in large quantities, in urban and industrial installations. Since chlorine is a toxic gas, its dispersion in such environments may have unpleasant consequences. On the point of Emergency Response Planning, it is important to know how such gases disperse. In this thesis, chlorine atmospheric dispersion is studied as an example of toxic dense gas dispersion. Chlorine accidental release from one of the storage tanks of Sohanak water refinery is selected for the case study. Laleh residential town is located in west of Sohanak refinery. According to the prevailing wind direction in Tehran (which is from the west to the east), the influence of the buildings of Laleh town on gas... 

One of the most important stages to designing a process plant is layout of equipment in unit area. There are plenty of routine procedures to find out equipment arrangement and their separation distances based on process and cost criteria. One of this Procedures is the use of codes and standards. Although some studies have been carried out to enter safety parameters to conventional procedures, the problem complexity because of the number of involved equipment is still of concern. To clear these ambiguities, the new approach presented in this thesis is aimed at quantifying the effects of adjacent equipment on each other. In this way, fire radiation and explosion have been selected as the major... 

Dust explosions are a serious hazard in many process industries and storage facilities. More than 70% of dusts processed in industry are combustible. This implies that majority of industrial plants that have dust processing equipment are susceptible to dust explosions. Dust explosions pose the most serious and widespread of explosion hazards in the process industry alongside vapour cloud explosions (VCE) and boiling liquid expanding vapour explosions (BLEVE). Dust explosions almost always lead to serious financial losses in terms of damage to facilities and down time. They also often cause serious injuries to personnel, and fatalities. In this project we presented a systematic algorithm in... 

There are different well-established strategies for making a process plant inherently safer. The benefits of applying these strategies on reducing the overall risk inside a plant are obvious. However, some of these changes are rejected many times because they appear to be too costly. But if the effects of applying inherently safer design strategies are investigated not only on the processing costs of a plant but also on the potential accident costs, the decision would in fact be different. In this paper an optimization procedure is proposed which integrates both processing and accident costs for different design schemes. In this procedure, some of the design variables are chosen with regard... 

The main application of flares is to protect facilities, staff, and surrounding area. Nevertheless, the flares flue gas contains environmental hazardous compounds like nitrogen oxides, sulfur oxides, and greenhouse gases like carbon dioxide and carbon monoxide. These compounds may spread in environment with unburned hydrocarbons. Due to the contamination risk and energy loss in flaring system, optimization and system enhancement is of vital importance. Flare gas recovery unit consist of equipment like multi-phase separator, Liquid Seal Drum, and compressor. The compressor is the most important part of this unit. Due to the process requirements and the probability of two-phase feed entering... 

As Ethylene Oxide is a highly toxic, flammable, and hazardous material, the consequences of any malfunction in an Ethylene Oxide reactor may be irreparable. The aim of this thesis is to evaluate the probable consequences of an accident in Morvarid Petrochemical Co.’s Ethylene Oxide Reactor in order to find probable hazardous scenarios. In this project, probable accidents were modelled and evaluated by Phast software in different scenarios, and the outcomes were investigated. In addition, if necessary, a set of solutions were proposed to decrease casualties in hazardous scenarios. The results may be used to change layouts according to Consequence Modelling. Results illustrated that... 

Today, Quantitative Risk Assessment (QRA) has become an efficient tool in decision making for safety and process experts. To assess the risk of any accident scenario, it is necessary that the probability of that event be determined in addition to estimating the probable consequences. Event tree and fault tree analysis are known to be the standard tools for calculating the frequency of incident outcomes.
In this research, a new method based on Markov chin and Fuzzy theory is presented to estimate the occurrence probability of events. A one of important parameter which has sufficient effect on probability of incident frequency, is inspection and maintenance interval. in this research... 

Emergency Shut Down systems are considered as one of the prominent protection layers in industries. In the situation that the process variables exist acceptable limits, the SIS brings the process in a safe state. According to standards, separate design and operation have been defined for BPCS and SIS. In this research, safety issues related to one of the gas refinery unit has been investigated. In fact, the unit does not have shut down system and all the safety loops are defined as DCS. In the first step, the Safety Integrated Levels of the loops which must be defined in shut down system have been specified by using Modified Calibrated Risk Graf. In next step, philosophy of shut down levels... 

Liquid ammonia atmospheric tank (20000 ton) attached to Pardis Petrochemical Complex was ruptured on 8th August 2011 due to overpressure blast injury so that ammonia gas was spread throughout the complex. The current study was aimed to evaluate ammonia leakage and emission from the tank. For this purpose, in addition to evaluate ammonia emission into the air, pressure changes were investigated to simulate the rupture. First of all, ammonia tanks and urea stocks were simulated and then considering two aerial classes (D and B), the incident was stimulated. According to this model, up to 1000 m, was contaminated with 1000 ppm of ammonia. Since there was no experimental data for validating the... 

Nowadays evolutionary algorithms help developers to solve many problems in applied science and engineering aspects. So the main goal of this thesis is to apply and verify the ability of evolutionary algorithms and artificial neural networks in optimization of Ethane recovery unit. Algorithms applied in this study are Ant Colony Algorithm, Artificial Immune Systems Algorithm, Incremental Evolutionary Algorithm, Chaotic Based Algorithm, Variable Population Size Genetic Algorithm, Frog Leaping Algorithm, Frog Leaping with Bacterial Optimization Approach and Different types of Particle Swarm Optimization Algorithm. Optimization methods based on local search are also applied in order to compare... 

Hazard analysis and risk assessment are the two significant methods of controlling and reducing risk caused by industrial units. To achieve the required safety needed in either new or operating plants, risk assessments are being used for some specific hazards such as fire, explosion and toxic release. Increasing industrial developments and occurrence of several catastrophic accidents in chemical processing plants have contributed to striking disasters and have obliged experts to use analytical solutions to evaluate frequencies and consequences of such events. Congested plants in industrial areas like Mahshahr and Asalouyeh in Iran and other places in the world are the reason why it has... 

In this thesis, behavior of multiple pool fires was investigated in the numerical method. Fire modeling is a complex process. The complexity intensify when simultaneous fires occurred, pool fire is the most likely among all kind of fires in city and industrial units. FDS software, a common CFD model for fire simulation, was used to simulate multiple pool fires. Using of CFD models is one of the most advanced techniques to fire simulation and FDS software have been used by engineers and researchers due to using of this technique. In the beginning, review of the existing investigations which FDS performance was examined of fire simulation is presented. Besides of the data gathering, in this... 

Nitroglycerine is an oily liquid and in pure form it is colorless. It is the main component of high explosives such as dynamites, and an essential ingredient of smokeless, double base propellants. The production of nitroglycerine has to solve the problems that arise from the extremely high mechanical sensitivity of the substance and the chemical instability of impure materials. Without sufficient control and mitigation of hazards, incidents have led to severe consequences, such as explosions, and threats to human lives, properties, and the environment. In this study, the hazard and operability study method is used to identify the existing hazards in the nitroglycerine production plant. Then,...