Showing papers in "Journal of Loss Prevention in The Process Industries in 2005"
TL;DR: Failure of oil and gas transmission pipelines was analyzed by fault tree analysis and the proposed method, which combined expert elicitation with fuzzy set theories to evaluate probability of the events, is effective to treat fuzzy events of FTA.
Abstract: Failure of oil and gas transmission pipelines was analyzed by fault tree analysis in this paper. According to failure modes of pipeline: leakage and rupture, a fault tree of the pipeline was constructed. Fifty-five minimal cut sets of the fault tree had been achieved by qualitative analysis, while the failure probability of top event and the important analyses of basic events were evaluated by quantitative analysis. In conventional fault tree analysis, probabilities of the basic events were treated as precise values, which could not reflect real situation of system because of ambiguity and imprecision of some basic events. In order to overcome this disadvantage, a new method was proposed which combined expert elicitation with fuzzy set theories to evaluate probability of the events. As an example, failure probability of pipeline installation was assessed by using the proposed method, achieving its fuzzy failure probability of 6.4603×10 −3 . The method given in this article is effective to treat fuzzy events of FTA.
348 citations
TL;DR: In this article, the laminar burning velocity of hydrogen-air mixtures was determined from pressure variations in a windowless explosion vessel, and the resulting velocities were seen to fall within the band of experimental data reported by previous researchers and to be close to values computed with a detailed kinetics model.
Abstract: The laminar burning velocity of hydrogen–air mixtures was determined from pressure variations in a windowless explosion vessel. Initially, quiescent hydrogen–air mixtures of an equivalence ratio of 0.5–3.0 were ignited to deflagration in a 169 ml cylindrical vessel at initial conditions of 1 bar and 293 K. The behavior of the pressure was measured as a function of time and this information was subsequently exploited by fitting an integral balance model to it. The resulting laminar burning velocities are seen to fall within the band of experimental data reported by previous researchers and to be close to values computed with a detailed kinetics model. With mixtures of an equivalence ratio larger than 0.75, it was observed that more advanced methods that take flame stretch effects into account have no significant advantage over the methodology followed in the present work. At an equivalence ratio of less than 0.75, the laminar burning velocity obtained by the latter was found to be higher than that produced by the former, but at the same time close enough to the unstretched laminar burning velocity to be considered as an acceptable conservative estimate for purposes related to fire and explosion safety. It was furthermore observed that the experimental pressure–time curves of deflagrating hydrogen–air mixtures contained pressure oscillations of a magnitude in the order of 0.25 bar. This phenomenon is explained by considering the velocity of the burnt mixture induced by the expansion of combusting fluid layers adjacent to the wall. q 2005 Elsevier Ltd. All rights reserved.
227 citations
TL;DR: In this article, the authors proposed a risk-based maintenance (RBM) approach to minimize the risk resulting from breakdowns or failures in power-generating units (PGUs).
Abstract: The unexpected failures, the down time associated with such failures, the loss of production and, the higher maintenance costs are major problems in any process plant. Risk-based maintenance (RBM) approach helps in designing an alternative strategy to minimize the risk resulting from breakdowns or failures. Adapting a risk-based maintenance strategy is essential in developing cost-effective maintenance policies. The RBM methodology is comprised of four modules: identification of the scope, risk assessment, risk evaluation, and maintenance planning. Using this methodology, one is able to estimate risk caused by the unexpected failure as a function of the probability and the consequence of failure. Critical equipment can be identified based on the level of risk and a pre-selected acceptable level of risk. Maintenance of equipment is prioritized based on the risk, which helps in reducing the overall risk of the plant. The case study of a power-generating unit in the Holyrood thermal power generation plant is used to illustrate the methodology. Results indicate that the methodology is successful in identifying the critical equipment and in reducing the risk of resulting from the failure of the equipment. Risk reduction is achieved through the adoption of a maintenance plan which not only increases the reliability of the equipment but also reduces the cost of maintenance including the cost of failure.
182 citations
TL;DR: An integrated inherent safety index (I2SI) was presented at the 37th Annual Loss Prevention Symposium of the AIChE (2003) and published in Process Safety Progress (volume 23(2), 136-148, 2004) as mentioned in this paper.
Abstract: This paper presents details of an integrated inherent safety index (I2SI) The conceptual framework of this index was presented at the 37th Annual Loss Prevention Symposium of the AIChE (2003) and published in Process Safety Progress (volume 23(2), 136–148, 2004) In addition to the framework, the current paper discusses additional features of the index such as the cost model and system design model, which were not presented or discussed earlier I2SI is called an integrated index because the procedure considers the life cycle of the process with economic evaluation and hazard potential identification for each option I2SI is comprised of sub-indices which account for hazard potential, inherent safety potential, and add-on control requirements In addition to evaluating these respective characteristics, there are also indices that measure the economic potential of the option To demonstrate the applicability and efficacy of I2SI, an application of the index to three acrylic acid production options is also discussed in the paper
164 citations
TL;DR: In this paper, the authors discuss the importance of using inherently safe process design, building on knowledge in powder science and technology, and of systematic education/training of personnel, and discuss how this kind of work will promote the development of means for prevention and mitigation of dust explosions in practice.
Abstract: In spite of extensive research and development for more than 100 years to prevent and mitigate dust explosions in the process industries, this hazard continues to threaten industries that manufacture, use and/or handle powders and dusts of combustible materials. Lack of methods for predicting real dust cloud structures and flame propagation processes has been a major obstacle to prediction of course and consequences of dust explosions in practice. However, work at developing comprehensive numerical simulation models for solving these problems is now on its way. This requires detailed experimental and theoretical studies of the physics and chemistry of dust cloud generation and combustion. The present paper discusses how this kind of work will promote the development of means for prevention and mitigation of dust explosions in practice. However, progress in other areas will also be discussed, e.g. ignition prevention. The importance of using inherently safe process design, building on knowledge in powder science and technology, and of systematic education/training of personnel, is also emphasized.
151 citations
TL;DR: In this article, the authors presented a site-oriented framework for risk assessment and developed a theoretical approach for emergency planning and optimisation of road transport systems, in particular in those countries, like Italy, in which 80% of goods are transported by this means.
Abstract: Despite the relative recent move towards inherent safe materials, the relentless drive of consumerism requires increased quantities of dangerous goods to be manufactured, transported, stored and used year on year. The safety and effectiveness of road transport systems is to be considered a strategic goal in particular in those countries, like Italy, in which 80% of goods are transported by this means. In this paper, we face the risk from dangerous good transport by presenting a site-oriented framework for risk assessment and developing a theoretical approach for emergency planning and optimisation. In the first step, we collected field data on a pilot highway and developed a database useful to allow a realistic evaluation of the accident frequency on a given route, by means of multivariate statistical analysis. To this end, we considered both inherent factors (such as tunnels, bend radii, height gradient, slope etc), meteorological factors, and traffic factors (traffic frequency of tank truck, dangerous good truck etc.) suitable to modify the standard national accident frequency. By applying the results to a pilot area, referring to flammable and explosive scenarios, we performed a risk assessment sensitive to route features and population exposed. The results show that the risk associated to the transport of hazardous materials, in some highway stretches, can be at the boundary of the acceptability level of risk set down by the well known F/N curves established in the Netherlands. On this basis, in the subsequent step, we developed a theoretical approach, based on the graph theory, to plan optimal emergency actions. The effectiveness of an emergency planning can normally be evaluated in term of system quickness and reliability. As a case study, we applied the developed approach to identify optimal consistency and localisation in the pilot area of ‘prompt action vehicles’, properly equipped, quick to move and ready for every eventuality. Applying this method results in an unambiguous and consistent selection criterion that allows reduction of intervention time, in connection with technical and economic optimisation of emergency equipment.
125 citations
TL;DR: An expert judgment technique, the Success Likelihood Index Methodology (SLIM), was adopted as a vehicle to predict human error probabilities during the process of emergency musters on offshore oil and gas production platforms.
Abstract: The focus of this work is on prediction of human error probabilities during the process of emergency musters on offshore oil and gas production platforms. Due to a lack of human error databases, and in particular human error data for offshore platform musters, an expert judgment technique, the Success Likelihood Index Methodology (SLIM), was adopted as a vehicle to predict human error probabilities. Three muster scenarios of varying severity (man overboard, gas release, and fire and explosion) were studied in detail. A panel of 24 judges active in the offshore oil and gas industry provided data for both the weighting and rating of six performance shaping factors. These data were subsequently processed by means of SLIM to calculate the probability of success for 18 muster actions ranging from point of muster initiator to the final actions in the temporary safe refuge (TSR). The six performance shaping factors considered in this work were stress, complexity, training, experience, event factors and atmospheric factors.
106 citations
TL;DR: The Hazwim framework offers support to prevention managers and safety policy makers concerning external domino prevention and offers a comprehensive up-to-date list of cross-company domino hazards and recommended actions in the area under consideration.
Abstract: Empirical research on major accident safety in the second largest chemical cluster worldwide, the Antwerp port area, supports the design of a meta-technical framework for optimizing external domino prevention. First, the majority of Seveso top tier companies have expressed a willingness to cooperate more intensively to protect themselves against potential off-site major accidents. Second, Hazop, What-If analysis and the Risk Matrix, interesting building blocks for such a framework, are frequently used risk analysis techniques at Seveso lower tier and Seveso top tier companies. The developed framework, called Hazwim, integrates these three complementary techniques into an effective standardized risk analysis framework for the prevention of external xdomino accidents in an industrial area. The main strengths of Hazwim are its completeness and its cost-effectiveness. The combination of techniques on the one hand and qualitative and quantitative data on the other, offers a comprehensive up-to-date list of cross-company domino hazards and recommended actions in the area under consideration. The Hazwim framework offers support to prevention managers and safety policy makers concerning external domino prevention.
105 citations
TL;DR: Three index based inherent safety evaluation methods are compared with expert evaluations on methyl methacrylate process routes and their subprocesses and their properties and limitations are discussed.
Abstract: In conceptual design, process routes can be compared and ranked by using inherent safety indices In this paper, some inherent safety index methods presented in literature are compared and their properties and limitations discussed As a case study, an inherent safety evaluation of methyl methacrylate process routes is presented Three index based inherent safety evaluation methods are compared with expert evaluations on methyl methacrylate process routes and their subprocesses Also the index based inherent safety ranking of process routes is compared with an expert ranking
89 citations
TL;DR: In this paper, the authors examine the risk analysis tools used by 24 chemical plants in Belgium, mainly located in the port of Antwerp, the second largest chemical cluster in the world after Houston, TX, USA.
Abstract: Risk analysis is an essential tool for company safety policy. Risk analysis consists of identifying and evaluating all possible risks. The efficiency of risk analysis tools depends on the rigueur of identifying and evaluating all possible risks. The diversity in risk analysis procedures is such that there are many appropriate techniques for any circumstance and the choice has become more a matter of taste. In this paper, we examine the risk analysis tools used by 24 chemical plants in Belgium, mainly located in the port of Antwerp, the second largest chemical cluster in the world after Houston, TX, USA. The aim of this paper is to identify the current practice in the chemical industry subject to European Seveso legislation and to examine how the present methods can be integrated to improve safety policy, especially towards preventing major accidents. Moreover, conclusions on the prevention of catastrophic external domino accidents involving several companies are formulated. This paper also gives impulse to investigating cross-company management implementations concerning external domino accident prevention.
82 citations
TL;DR: The process life cycle phases and the possibilities of implementing and evaluating inherent safety are discussed, and the applicability and accuracy of an inherent safety index method is presented by a case study.
Abstract: Inherent safety should be implemented as early as possible in the design life cycle, since the changes in process design are easier and cheaper the earlier they are done. The problem is, how to evaluate process alternatives in the terms of inherent safety in the early design phases, when much of the information is missing. In this paper the process life cycle phases and the possibilities of implementing and evaluating inherent safety are discussed. The applicability and accuracy of an inherent safety index method is presented by a case study.
TL;DR: In this article, a suite of fire consequence models such as individual fire models, radiation model, overpressure model, smoke and toxicity models and human impact models were considered for the unique conditions found offshore.
Abstract: Offshore oil and gas platforms are well known for their compact geometry, high degree of congestion, limited ventilation and difficult escape routes. A small mishap under such conditions can quickly escalate into a catastrophe. Among all the accidental process-related events occurring offshore, fire is the most frequently reported. It is, therefore, necessary to study the behavior of fires and quantity the hazards posed by them in order to complete a detailed quantitative risk assessment. While there are many consequence models available to predict fire hazards-varying from point source models to highly complex computational fluid dynamic models—only a few have been validated for the unique conditions found offshore. In this paper, we have considered fire consequence modeling as a suite of sub-models such as individual fire models, radiation model, overpressure model, smoke and toxicity models and human impact models. This comprehensive suite of models was then revised by making the following modifications: (i) fire models: existing fire models have been reviewed and the ones most suitable for offshore conditions were selected; (ii) overpressure impact model: a model has been developed to quantify the overpressure effects from fires to investigate the possible damage from the hot combustion gases released in highly confined compartments; (iii) radiation model: instead of a point/area model, a multipoint grid-based model has been adopted for better modeling and analysis of radiation heat flux consequences. A comparison of the performance of the revised models with the ones used in a commercial software package for offshore risk assessment was also carried out and is discussed in the paper.
TL;DR: In this article, the influence of water and humidity on the self-ignition of combustible bulk materials was investigated and a numerical model was established to describe the effects of self-heating until ignition of the deposit.
Abstract: The current paper presents experimental investigations as well as numerical simulations on the influence of water and humidity on the self-ignition of combustible bulk materials. It is well known, that bulk materials may undergo self-ignition if stored under specific conditions. In some cases, large amounts of these materials are exposed to a humid surrounding, e.g. dried coal in a moist atmosphere. Due to the effects of condensation and adsorption of water, additional heat is generated and transported into the bulk material. If the pile is stored slightly below its self-ignition temperature, the bulk material can become supercritical and an ignition occurs. Experiments were carried out for German lignite coal sampled in two different particle size fractions. They showed, that subcritical deposits turned to supercritical behaviour if the relative humidity in the surrounding was suddenly increased or water was poured on the surface of the sample. Besides the experiments, a numerical model was established to describe the effects of self-heating until ignition of the deposit, including the transportation of moisture. Simulations with this model led to satisfying results when compared to the experiments.
TL;DR: As an employee of Union Carbide India at the Bhopal plant, I know how the disaster happened and the merciless cost-cutting severely affecting materials of construction, maintenance, training, manpower and morale resulted in the disaster that was waiting to happen as mentioned in this paper.
Abstract: As an employee of Union Carbide India at the Bhopal plant, I know how the disaster happened. The merciless cost-cutting severely affecting materials of construction, maintenance, training, manpower and morale resulted in the disaster that was waiting to happen. Significant differences between the West Virginia, USA plant and the Bhopal, India plant show the callous disregard of the corporation for the people of the developing countries. The narrative below, if given a proper thought by the management and governments, should help in significantly reducing industrial accidents.
TL;DR: In this paper, a technique to protect the integrity of neighboring structures is proposed, called the water spray curtain, which can be operating downward in front of or oriented to the surface to be shielded.
Abstract: The mitigation of the consequences of storage-tank fire is a great safety concern in petro-chemical and gas industries. A technique to protect the integrity of neighbouring structures is the water spray curtain. It can be operating downward in front of or oriented to the surface to be shielded. Simple modelling, laboratory experiments and field tests for these two types of thermal shielding are presented. Attenuation factor of 50–75% can be expected with the vertical curtain while 90% can be reached with the impinging curtain if spray overlapping is achieved.
TL;DR: In this paper, Accelerating Rate Calorimetry (ARC) was used to evaluate the thermal stability of DME and DIPE, a known peroxide producers, under adiabatic and various atmospheric conditions.
Abstract: The Japanese government is planning to introduce DME as a substituted energy for oil and LNG. Introduction of DME could contribute greatly to both the prevention of global warming and the formation of resource-recycling societies. In these circumstances, a safety assessment of DME is very important when DME is used on a large scale. There is a possibility that prolonged exposure in air induces autoxidation to produce explosive organic peroxides during transportation and storage of DME. Therefore, the reactivity of DME with oxygen and the mechanism of the autoxidation were investigated. Accelerating Rate Calorimetry (ARC) was used to evaluate the thermal stability of DME and DIPE, a known peroxide producers, under adiabatic and various atmospheric conditions. In ARC studies of DME under oxygen, exothermic decompositions were detected although its self-heating rate was low in comparison with DIPE. Oven storage tests were carried out and iodimetry was used to measure the concentration of peroxides produced from DME in comparison with DIPE and DEE. However, no products could be found for DME either by GC/MS or by iodimetry, while some evidence of autoxidation of both DEE and DIPE were obtained from these experiments.
TL;DR: In this article, the propagation of a flame is investigated experimentally and theoretically for a large, horizontal combustion tube containing a mixture of air and aluminum powder with pre-existing turbulence, one end of the tube is closed and the other is connected to a large dump-tank.
Abstract: The propagation of a flame is investigated experimentally and theoretically for a large, horizontal combustion tube containing a mixture of air and aluminum powder with pre-existing turbulence. One end of the tube is closed and the other is connected to a large dump-tank. Twenty dispersion systems are used on the tube to produce a uniform suspension of aluminum dust in the tube with a mean diameter of 6 μm. The characteristics of a flame front from the ignitors at the closed end are measured using photodiodes and the development of pressure is monitored by transducers. Experimental results revealed the entire process of an accelerating flame and the development of shock waves. A set of conservation equations for two-phase turbulent combustion flow is derived, using the two-fluid model, k – e model, Hinze–Tchen model and EBU-Arrhenius model for turbulent combustion. The SIMPLE scheme usually applied to the homogeneous turbulent combustion is extended to fit this two-phase, reactive behavior. The results of calculations show the positive feedback coupling among combustion, expansion and turbulence during flame propagation. Computed and measured results are generally in good agreement.
TL;DR: In this article, the authors applied risk-based inspection (RBI) methodology to optimize the inspection strategy of the piping in a refinery and petrochemical plants in Taiwan, and two actual case studies were corroborated better with quantitative RBI methodology than without the methodology in terms of risk and cost reductions.
Abstract: In refineries and processing plants, the enormous amount of piping is more complex in distribution than other types of equipment. In general, compared with other types of equipment in these industries, more difficulty in inspection planning is encountered. However, under-inspection or over-inspection can occur due to the lack of jurisdictional requirements on the inspection interval and method for piping, or the inspection interval being based only on piping service classifications in the existing regulations, such as API 570. This can result in unacceptable risks, along with costly loss of resources. To lessen the piping risk level, more and more companies have adopted and applied risk based inspection (RBI) methodology, leading to risk reduction and cost benefits since the last decade. This study applied RBI methodology to optimize the inspection strategy of the piping in a refinery and petrochemical plants in Taiwan. Two actual case studies were corroborated better with quantitative RBI methodology than without the methodology in terms of risk and cost reductions.
TL;DR: In this paper, the authors demonstrate the application of isothermal calorimeter for investigating the thermal decomposition of several liquid organic peroxides, such as t-Butyl peroxy acetate (TBPA), Di-tert butyl peroxide (DTBP), and Cumene hydroperoxide (CHP).
Abstract: This study demonstrates the application of isothermal calorimeter for investigating the thermal decomposition of several liquid organic peroxides, such as t-Butyl peroxy acetate (TBPA), Di-tert butyl peroxide (DTBP), and Cumene hydroperoxide (CHP). The decomposition mechanism and kinetic can be identified from case to case. TBPA and DTBP undergo first order reaction, whereas CHP occurs autocatalysis. Accurate kinetic can be assessed on the basis of discerning these various schemes of given samples. Consequently, the thermal runaway or reactive hazards potential of organic peroxides can be determined, for instance as a self accelerating decomposition temperature (SADT).
TL;DR: In this paper, the spontaneous combustion of Refuse Derived Fuel (RDF) without additional water was examined by Thermogravimetry and Differential Thermal Analysis and Spontaneous Ignition Tester.
Abstract: In order to clarify the scenario of fires and accidents resulting from spontaneous combustion of Refuse Derived Fuel (RDF), exothermic phenomenon of RDF with water at ambient temperature was characterized by Calvet calorimeter (C 80 and MS 80), Thermal Activity Monitor and Dewar. The spontaneous combustion characteristic of RDF without additional water was examined by Thermogravimetry and Differential Thermal Analysis and Spontaneous Ignition Tester. The experimental results show the heat generation of RDF with different water content occurred instantly after additional water was added into RDF, while no exothermic phenomenon can be observed if no additional water was added into RDF at room temperature. It means that the self-heating of RDF does not only result from fermentation of RDF because of the prompt heat generation and temperature rise of RDF with water. It is possible that the self-heating of RDF results from heat of wetting first when additional water/vapor is absorbed by RDF. The further quantitative analysis for the self-heating of RDF with water/vapor should be made to explain the process of spontaneous combustion of RDF in detail.
TL;DR: In this article, the authors discuss the impact of the Bhopal disaster on chemical process safety, and the challenges that must be addressed to reduce the frequency and severity of chemical process incidents.
Abstract: Chemical process safety was not a major public concern prior to 1984. As far as chemical hazards were concerned, public fears focused on disease (cancer) and environmental degradation. Even a series of major process incident tragedies did not translate into widespread public concerns about major incidents in chemical plants that might disastrously affect the public. This situation changed completely after the December 1984 disaster at the Union Carbide plant in Bhopal. Not only was the public's confidence in the chemical industry shaken, the chemical industry itself questioned whether its provisions for protection against major incidents were adequate. The recognition of the need for technical advances and implementation of management systems led to a number of initiatives by various stakeholders throughout the world. Governments and local authorities throughout the world initiated regulatory regimes. Has all that has resulted from the legacy of Bhopal reduced the frequency and severity of incidents? How can we answer this question? As we move into more and more globalization and other complexities what are the challenges we must address? According to the authors, some of these challenges are widespread dissemination and sharing of lessons learned, risk migration because of globalization, changing workforce, and breakthroughs in emerging areas in process safety.
TL;DR: In this paper, a cylindrical vessel with a vent duct and four transducers mounted in the line-of-sight centerline outside the vessel and the clear sequential shadowgraphs of external venting flow field taken by a high-speed shadowgraph imaging system were obtained.
Abstract: Experiments of explosion venting in different conditions were performed in a cylindrical vessel with a vent duct; the pressure-time profiles from four transducers mounted in the line-of-sight centerline outside the vessel and the clear sequential shadowgraphs of external venting flow field taken by a high-speed shadowgraph imaging system were obtained. Based on these results, the characteristics of the external pressure field during venting were discussed systematically to explain the generation mechanism of the secondary explosion. In addition, the variations of the intensity of the secondary explosion in different venting conditions, namely the failure pressure, ignition location, area blockage ratio or equivalence ratio of the fuel, were also analyzed in detail.
TL;DR: In this paper, Haddon's and Berger's models for injury analysis have been tested, together with the project planning tool Logical Framework Approach (LFA), and three models provide the same main message: that irrespectively of the direct cause to the leakage, it is only two parties that are responsible for the magnitude of the disaster: Union Carbide Corporation and the Governments of India and Madhya Pradesh.
Abstract: The Bhopal Gas Leak, India 1984 is the largest chemical industrial accident ever. Haddon's and Berger's models for injury analysis have been tested, together with the project planning tool Logical Framework Approach (LFA). The three models provide the same main message: That irrespectively of the direct cause to the leakage, it is only two parties that are responsible for the magnitude of the disaster: Union Carbide Corporation and the Governments of India and Madhya Pradesh. The models give somewhat different images of the process of the accident. Models developed for analysis of injuries can be used for analysing a complicated mega accident like the Bhopal gas leak, although different models might stress different aspects.
TL;DR: In this article, a new method called SREST-layer-assessment method with automated software tool is presented that in a hierarchical approach reveals the degree of nonideality of chemical processes with regard to SHE (safety, health and environment) aspects at different layers: the properties of the chemical substances involved (substance assessment layer (SAL)), possible interactions between the substances (reactivity assessment layer), possible hazard scenarios resulting from the combination of substances and operating conditions in the various equipments involved (EAL)), and the safety technologies that are required to run a process safely and
Abstract: A new method called SREST-layer-assessment method with automated software tool is presented that in a hierarchical approach reveals the degree of non-ideality of chemical processes with regard to SHE (safety, health and environment) aspects at different layers: the properties of the chemical substances involved (substance assessment layer (SAL)), possible interactions between the substances (reactivity assessment layer (RAL)), possible hazard scenarios resulting from the combination of substances and operating conditions in the various equipments involved (equipment assessment layer (EAL)), and the safety technologies that are required to run a process safely and in accordance with legal regulations (safety-technology assessment layer (STAL)). In RAL, EAL and STAL the main focus is put on process safety. A case study is used to show the principles of the method. It is demonstrated how the method can be used as a systematic tool to support chemical engineers and chemists in evaluating chemical process safety in early process development stages.
TL;DR: In this article, the results of a round-robin test on the decomposition reaction of 15% w/w di-tertiary-butyl peroxide (DTBP) in toluene are described.
Abstract: The results of a Round-Robin test on the decomposition reaction of 15% w/w di-tertiary-butyl peroxide (DTBP) in toluene are described in the present paper. The aim of the Round-Robin test was to compare the results of different (pseudo-)adiabatic reaction calorimeters in terms of accuracy and reliability for practical applications. The experiments were performed in the Accelerating Rate Calorimeter (ARC), Phi-Tec, Pressure Dewar calorimeter (Dewar), temperature controlled reactor (CRVM) and the Automatic Pressure Track Accelerating Calorimeter (APTAC). Although the various types of equipment showed differences in accuracy and reproducibility, in general, no specific type of equipment seems to out-perform the others in the present study.
TL;DR: In this article, an exact algebraic expression for the upper limit value of the explosion constant of gaseous fuels, Kmax, is derived by using a two-zone model for the adiabatic combustion in closed vessels.
Abstract: An exact algebraic expression for the upper limit value of the explosion constant of gaseous fuels, Kmax, is derived by using a two-zone model for the adiabatic combustion in closed vessels. The expression is formulated in terms of the mean specific heat ratio of the unburned reactants gu and introduces the concept of an apparent specific heat ratio of the burned products gb. Computational data are presented for a set of representative fuels and for a range of equivalence ratio’s, initial pressures and initial temperatures. A comparison of these data with correlations from literature shows that one correlation in particular is in close agreement with the exact result. This one-parameter correlation is based upon the almost linear relationship between the fraction of burned mass and the pressure, a relationship which is taken from the original work of Lewis and von Elbe. Based upon this theoretical work, formulas are suggested that can be used to estimate the explosion constant of fuel/air mixtures with a minimum level of computational effort. In addition, because the derivation in this paper is fairly straightforward and because the resulting expression is rather simple, the analysis presented in this paper can be used in combustion courses as an exercise in thermodynamics and as an illustration of the concept of the flame speed. q 2004 Elsevier Ltd. All rights reserved.
TL;DR: In this paper, the then Mayor and Chief of Police of Bhopal were the two people on whom the responsibility of handling the world's worst industrial disaster fell unceremoniously on the cold night of December 2-3, 1984 when 41 tons of MIC gas was released from the Union Carbide plant in Kannanagar.
Abstract: We, the then Mayor and Chief of Police of Bhopal, were the two people on whom the responsibility of handling the world's worst industrial disaster fell unceremoniously on the cold night of December 2–3, 1984 when 41 tons of MIC gas was released from the Union Carbide plant in Bhopal. With the company initially in denial mode about the release and then calling it a ‘tear-gas’ type and providing no information on antidote, and with the limited means of evacuation, handling of medical emergency affecting hundreds of thousand, identification and disposal of the thousands of dead, it was probably the most challenging task faced by a duo in peace time. The local people, the medical community, the railway staff, the NGOs, were all very helpful. We narrate the happening and the handling of the consequences and the spot decisions that had to be made with the hope that no such accident happens anywhere.
TL;DR: In this article, an approach based purely on steady-state analyses for synthesizing effective control structures for reactive distillation (RD) columns is presented, where the main idea is to analyze the steady state relationships between the manipulated (input) variables and the potential controlled (output) variables to identify input-output (IO) pairings that are sensitive and avoid steady state multiplicities providing a large range of nearly linear operating region around the base case design.
Abstract: An approach, based purely on steady-state analyses, for synthesizing effective control structures for reactive distillation (RD) columns is presented. The main idea is to analyze the steady-state relationships between the manipulated (input) variables and the potential controlled (output) variables to identify input–output (IO) pairings that are sensitive and avoid steady-state multiplicities providing a large range of nearly linear operating region around the base case design. Traditional SISO control loops are then implemented using these IO pairings to obtain control structures that maintain the column near the design product purity and conversion for the anticipated primary disturbances. The Niederlinski Index is used to eliminate dynamically unstable pairings in control structures with multiple loops. The approach is demonstrated on an example MTBE RD column. The impact of steady-state multiplicities on control structure design is highlighted.
TL;DR: In this article, a safety management system is planned for a mine operation, where the objective is to develop a mine production design that will achieve the desired reliability and variance of reliability estimation of system while performing all sub-system functions at a minimum cost.
Abstract: In this research, a safety management system is planned for a mine operation. The objective is to develop a mine production design that will achieve the desired reliability and variance of reliability estimation of system while performing all sub-system functions at a minimum cost. The problem was formulated in an underground mine system containing five sub-systems with varying reliability estimates, estimation variances and feasibilities and solved by genetic algorithms (GA).
TL;DR: In this paper, the authors present a methodology to quantify the forced dispersion factor provided by a water-curtain with respect to its configuration, which involves medium-scale field tests, wind-gallery tests and numerical simulations.
Abstract: The mitigation of the consequences of accidental releases of dangerous toxic and/or flammable cloud is a serious concern in the petro-chemical and gas industries. Nowadays, the water-curtain is recognized as a useful technique to mitigate a heavy gas cloud. The paper presents a research methodology, which has been established and undertaken to quantify the forced dispersion factor provided by a water-curtain with respect to its configuration. The method involves medium-scale field tests, Wind-Gallery tests and numerical simulations. These different approaches are discussed and exemplified by typical results emphasizing the observed concentration reduction due to the water-curtain.