Sharif Digital Repository

Ethylene oxide production units are among the most dangerous plants in the petrochemical industry. A detailed consequence analysis for different accidental scenarios for a storage tanks in a petrochemical complex in Iran is put forward. Credible scenarios were selected and all the effective factors that may influence the mechanism of release and dispersion of toxic materials were surveyed. Simulator software and numerical models were used to simulate the distribution of toxic material around the leak source. The results can be used in risk management and in providing an emergency response plan to counter unwanted situations in the plant. This is an abstract of a paper presented at the 7th... 

Nowadays the application of decision support systems (DSSs) in process safety is more important than ever. The use of DSS for preventing domino effects is one of the diverse applications of these computer-automated toolkits. Different software packages were developed in recent years, each trying to manage domino risk by a specific approach. In this chapter, the definition, architecture, benefits and essential characteristics of DSS toolkits are described. The application, scope, approach, technical features, advantages, shortcomings and limitations of all the available computerized tools and software packages presented up to now for managing domino effect are then discussed and analyzed... 

API Publication 2218 is one of the most referred practices for fireproofing of onshore structural supports. Despite the extensive citation, it solely considers the effects of pool fire and rarely addresses jet fire outcomes. This absence of an explicit approach is common among all the other major references. Therefore, the basic objective of this paper is to introduce a new approach for determination of the necessity for fireproofing of structural supports against jet fires. For this purpose, the flame geometry and duration of jet fires are simulated for different leak sizes in identified fire potential sources. Then, following a worst-case analysis, those structures that may be impinged by... 

Pool fire modeling and risk assessment is very important and essential especially in systems with large flammable fuel inventories, e.g., refineries, offshore oil platforms, or fuel transportation systems. Results obtained from pool fire risk assessment can be used in setting up safety measure or emergency planning. Pool fire modeling is used to evaluate the heat flux at various target points around the fire source. The two major approaches in pool fire modeling are semi-empirical models and Computational Fluid Dynamics (CFD), which are called field models. Semi-empirical models are based on correlations fitted to data from large-scale Experiments and are used more frequently than CFD models... 

Nowadays "as everywhere in the world", so much attention is drawn to performing safety and HSE management rules in Iran. Considering the long life of oil and it's relevant industries in Iran (since 1908, first oil well in Middle East, Masjid Soleyman), many units with more than 50 years old are still in operation. This situation posed special problems in performing safety and HSE regulations that some of them are communal among these units. This paper reveals the result of industrial projects, collecting numerous technical checklists in such units and author's experiences in recent years in Iran, which is aimed to announce some of these major problems and also present solutions for them.... 

This paper outlines a quantitative risk assessment for an 110,000 ton/day ethylene oxide production plant in Iran. After a complete and detailed hazard identification study, done by HAZOP method, the purification column was found to be one of the most hazardous sections in this plant. As ethylene oxide with high concentration and inventory is present there. Fault tree analysis (FTA) technique has been used to identify the basic events responsible for top event occurrence and also calculation of top event frequency of occurrence. Human error has been calculated numerically and probability of human error has been estimated. Failure rate data were collected referring to several sources and... 

Nowadays "as everywhere in the world", so much attention is drawn to performing safety and HSE management rules in Iran. Considering the long life of oil and it's relevant industries in Iran (since 1908, first oil well in Middle East, Masjid Soleyman), many units with more than 50 years old are still in operation. This situation posed special problems in performing safety and HSE regulations that some of them are communal among these units. This paper reveals the result of industrial projects, collecting numerous technical checklists in such units and author's experiences in recent years in Iran, which is aimed to announce some of these major problems and also present solutions for them  

In this study, a well-known Computational Fluid Dynamics software, so-called Fire Dynamics Simulator (FDS), has been used to simulate multiple ethanol pool fire scenarios. Influences and reciprocal impacts in terms of dynamics and growth of the pool fires have been investigated. Heat release rates temperature and flame shapes have been monitored as the main outputs of the simulations. Based on the simulation results, it can be concluded that the amounts of mass burning rate, the radiation energy and the pool fire flame height were significantly higher in multiple pool fires, when compared with the theoretical values obtained by the mere summation of single pool fires. Furthermore, the... 

The paper presents an inventory, perhaps the most comprehensive till date, of the major process-industry accidents involving 'domino effect'. The inventory includes, among other relevant information, the sequence of accidents that had occurred in each domino episode. The information has been analyzed to identify several patterns which may be useful in further work on understanding domino effect and reducing the probability of its occurrence in future. A concept of 'local domino effect' has been introduced  

A new methodology is presented with which the likely impact of accident in one process unit of an industry on other process units can be forecast and assessed. The methodology is based on Monte Carlo Simulation and overcomes the limitations of analytical methods, used hitherto, which were inherently limited in their ability to handle the uncertainty and the complexity associated with domino effect phenomena. The methodology has been validated and its applicability has been demonstrated with two case studies  

On July 24th, 2010, several explosions and fires devastated a hydrocarbon processing plant in Kharg Island, Iran. Four workers were killed and many others were severely injured. The plant became out of service for 80 days. The way the accident happened and its sequence was representing as a domino accident. In this paper, events leading up to the disaster have been analyzed in details. Graphic presentation techniques such as Fish Bone Analysis and Event Sequence Diagram (ESD) have been utilized to enhance the understanding of the accident mechanism. Finally major lessons learnt from this domino accident have been addressed  

γ-Alumina is used to catalyze the Cannizzaro reaction in the absence of any base under microwave irradiation in high yields. In the case of terephthalaldehyde the reaction is carried out with high selectivity  

Enolizable ketones have been reacted in a one-pot method with aromatic aldehydes, acetyl chloride and acetonitrile at room temperature in the presence of SnCl4/SiO2 to furnish the corresponding β-acetamidoketones in improved yields. Acetylation of an aromatic hydroxyl group was observed while using 4-hydroxybenzaldehyde or vanillin and the corresponding β-acetamidoketones were isolated in an excellent yield  

The boundary layer integral method is used to investigate the development of the turbulent swirling flow at the entrance region of a conical nozzle. The governing equations in the spherical coordinate system are simplified with the boundary layer assumptions and integrated through the boundary layer. The resulting sets of differential equations are then solved by the fourth-order Adams predictor-corrector method. The free vortex and uniform velocity profiles are applied for the tangential and axial velocities at the inlet region, respectively. Due to the lack of experimental data for swirling flows in converging nozzles, the developed model is validated against the numerical simulations. The... 

The governing equations of two-dimensional steady density currents are solved numerically using a finite volume method. The v2̄-f turbulence model, based on standard k - s model, is used for the turbulence closure. In this method, all Reynolds stress equations are replaced with both a transport equation for v2̄ and an elliptic relaxation equation for f, a parameter closely related to the pressure strain redistribution term. The Simple-C procedure is used for pressure-velocity coupling. In addition, Boussinesq's approximation is used to obtain the momentum equation. The computed height of the progressive density current is compared to the measured data in the literature, resulting in good... 

The deposition behavior of fine sediment is an important phenomenon, and yet unclear to engineers concerned about reservoir sedimentation. An elliptic relaxation turbulence model (v2̄ - f model) has been used to simulate the motion of turbid density currents laden whit fine solid particles. During the last few years, the v2̄ - f turbulence model has become increasingly popular due to its ability to account for near-wall damping without use of damping functions. In addition, it has been proved that the v2̄ - f model to be superior to other RANS methods in many fluid flows where complex flow features are present. Due to low Reynolds number turbulence of turbidity current,(its critical Reynolds... 

In this paper, an analytical solution for steady creeping motion of viscoelastic drop falling through a viscous Newtonian fluid is presented. The Oldroyd-B model is used as the constitutive equation. The analytical solutions for both interior and exterior flows are obtained using the perturbation method. Deborah number and capillary numbers are considered as the perturbation parameters. The effect of viscoelastic properties on drop shape and motion are studied in detail. The previous empirical studies indicated that unlike the Newtonian creeping drop in which the drop shape is exactly spherical, a dimpled shape appears in viscoelastic drops. It is shown that the results of the present... 

In this paper, creeping motion of a viscoelastic drop falling through a Newtonian fluid is investigated experimentally and analytically. A polymeric solution of 0.08 % xanthan gum in 80:20 glycerol/water and silicon oil is implemented as the viscoelastic drop and the bulk viscous fluids, respectively. The shape and motion of falling drops are visualized using a high speed camera. The perturbation technique is employed for both interior and exterior flows, and Deborah and capillary numbers are considered as perturbation parameters up to second order. The product of Deborah and capillary numbers is also used as a perturbation parameter to apply the boundary condition on the deformation on the...