Russell Ogle - Academia.edu (original) (raw)

Papers by Russell Ogle

Mary Kay O'Connor Process Safety Center, 2000

Due to the large quantities of hazardous chemicals, an accident at a chemical facility can have s... more Due to the large quantities of hazardous chemicals, an accident at a chemical facility can have serious consequences. The owner/operator of a chemical facility has a great interest in investigating the cause of any accident as a basis for corrective action. The lessons learned from an accident investigation can be instrumental in preventing a recurrence. However, there can be many other stakeholders in a chemical accident, including regulatory authorities (e.g., the Occupational Safety and Health Administration (OSHA) and the United States Environmental Protection Agency (USEPA)) and advisory agencies (e.g., the Chemical Safety and Hazard Investigation Board (CSB) and the National Transportation Safety Board (NTSB)). How well do these organizations investigate chemical accidents? What can we learn from their recent investigations? This paper critically examines investigations conducted by OSHA, USEPA, CSB and NTSB. The scope of this investigation is restricted to a sample of published reports available during the five-year period 1995-1999. The survey of reports includes an analysis of the chemicals involved in the accidents as well as the types of equipment and work activities. Consideration is given to the identification of causal factors and the proposed corrective actions. The analytical tools used in the investigations are compared and the overall methodology is assessed. Finally, the lessons learned from these investigations are reviewed and compared with case studies drawn from the chemical process safety literature.

Journal of Loss Prevention in the Process Industries, 2021

One of the more obvious consequences of a dust deflagration inside process equipment or a structu... more One of the more obvious consequences of a dust deflagration inside process equipment or a structure is the mechanical damage caused by shock (compression) waves. This overpressure damage is revealed through the displacement of equipment, the outward deformation or rupture of enclosures constructed of ductile materials, or the projection of missiles. However, a different type of damage is sometimes observed in the ductwork connecting process equipment. In particular, the ductwork is collapsed as if it were subjected to an external, rather than an internal pressure. The phenomenon that causes this collapse of thin-walled conduit is a gas dynamic process called an expansion wave. When a dust deflagration travels through a conduit, it accelerates and causing a rise in pressure. When the dust deflagration is vented (say through a deflagration vent), the discharge of the high pressure combustion products causes the formation of an expansion wave that travels in the reverse direction from the vent backwards. The expansion wave causes the pressure in the ductwork to fall below atmospheric pressure. The sub-atmospheric pressure, in turn, causes the ductwork to fail by buckling. In this study, we examine the gas dynamics of the expansion wave, demonstrate how to calculate the degree of pressure drop caused by the expansion wave, and illustrate the concept with case studies of dust explosions.

Journal of Loss Prevention in the Process Industries, 2019

There are many sources of mechanical energy in agricultural processing facilities. This is partic... more There are many sources of mechanical energy in agricultural processing facilities. This is particularly true when milling is performed. If mechanical energy turns into sufficient thermal energy (heat), it can cause material to smolder. If that smoldering material is fluidized, e.g., through pneumatic conveyance or air/material separation, a deflagration may occur. A case study of an explosion at a wheat milling facility is used to illustrate the hazard. Fugitive grain dust played no role in the event, and no secondary explosion occurred. Although the equipment involved in this incident was vented in accordance with NFPA guidance, a significant portion of the facility was destroyed in the explosion. The severity of the resulting explosion damage resulted, in part, due to the initial conditions assumed in this typical explosion vent design, which did not consider the effects of flame acceleration and pressure piling upstream of the vented filter house. First, we present a basic overview of milling operations, particularly equipment involved in material separation and size reduction. Then we detail the investigation of this incident. Equipment damage, witness observations, and material properties are used to determine the cause. Finally, we discuss lessons learned. Particular attention is paid to milling safeguards and the effects of flame acceleration in the context of the damage observed.

Process Safety Progress, 2018

Ignition by electrostatic discharge of clean flammable gas, such as natural gas, being released t... more Ignition by electrostatic discharge of clean flammable gas, such as natural gas, being released to the atmosphere during blowdown operations is unlikely. However, the presence of foreign material in the form of solid particles or liquid droplets changes the risk level significantly. The discharge of a flammable gas stream with a cloud of foreign material poses a potential electrostatic hazard, even if the piping system and associated equipment is otherwise bonded and grounded. The foreign material may be capable of accumulating sufficient electrostatic potential to ignite the flammable gas. There have been several documented incidents where ignition has occurred during a flammable gas blowdown. In some instances, gas lines were being cleaned, while in others, the blowdown was completed as a safety measure for another process. This article will focus on a case study where a stream of flammable gas was ignited during a blowdown and an obvious ignition source (other than electrostatic discharge) was not present, but foreign material was observed.

Process Safety Progress, 2018

Incorporating inherently safer design (ISD) into a process safety program can benefit a site's ov... more Incorporating inherently safer design (ISD) into a process safety program can benefit a site's overall process safety program. However, ISD solutions are rarely capable of being implemented without consideration of various tradeoffs associated with other critical operating factors at a plant. Critics have often accused companies of failing to implement ISD solely on the basis of cost, often neglecting other factors that must be accounted for in the decision. Multiattribute decisions are difficult to resolve, but there are tools available to assist the decision maker. One such tool that can be applied to provide insight into the implementation of ISD solutions is multiattribute utility theory (MAUT). MAUT is a structured approach that evaluates the strengths and weaknesses of competing solutions for a problem with multiple objectives. In this article, the concept of MAUT will be explained. Then MAUT analysis will be applied to three case studies where investigators have recommended incorporating ISD or technology into a process. Using MAUT analysis, the benefit of the proposed design change will be evaluated in a systematic, semiquantitative methodology that will demonstrate how the tools can help facility personnel understand and characterize the benefits of ISD.

Volume 14: Emerging Technologies; Engineering Management, Safety, Ethics, Society, and Education; Materials: Genetics to Structures, 2014

ABSTRACT This paper explores an infrequently encountered hazard associated with liquid fuel tanks... more ABSTRACT This paper explores an infrequently encountered hazard associated with liquid fuel tanks on gasoline-powered equipment using non-vented fuel caps. Depending on the location of fuel reserve tanks, waste heat from the engine or other vehicle systems can warm the fuel during operation. In the event that the fuel cap is not vented and if the fuel is sufficiently heated, the liquid fuel may become superheated and pose a splash hazard if the fuel cap is suddenly removed. Accident reports often describe the ejection of liquid from the fuel tank opening as a geyser. This geyser is a transient, two-phase flow, vertical jet of flashing liquid. This could create a fire hazard as the geyser could result in splashing flammable liquid onto any bystanders. Many fuel tank systems are vented to ambient through the fuel tank cap and, in addition, may incorporate other features that contribute to pressure relief. Venting of the pressurized vapor inhibits the vapor-liquid mixture in the fuel tank from achieving thermodynamic equilibrium, thus preventing the formation of a superheated liquid. It has been empirically determined that flashing two-phase flow can be prevented by keeping the fuel tank pressure below 1.5 psig. However, if the cap is not vented or vents at a lesser rate than the rate of liquid vaporization, pressure in the tank can rise and the flammable liquid can become superheated. This phenomenon is explored here to facilitate a better understanding of how the hazard is created. The nature of the hazard is explained using thermodynamic concepts. The differences in behavior between a closed system and an open system are discussed and then illustrated through experimental results obtained from two sources: experiments with externally heated fuel containers and operation of a gasoline-powered riding lawn mower. The role of the vented fuel cap in preventing the geyser phenomenon is demonstrated. INTRODUCTION Gasoline powered equipment has remained a centerpiece of the industrialized world since scaled manufacturing began in the early 20 th century. The fundamental makeup of these systems has not changed in that a reserve fuel tank is mounted on the equipment and gradually depleted during operation as fuel is withdrawn for combustion in the engine. To provide for continued operation, the fuel tank must intermittently be refilled, which requires accessing the tank's interior by removal of a cap or other tank closure. This paper examines a potential hazard associated with superheating gasoline in a closed system. Depending on the location of fuel reserve tanks, waste heat from the engine or other vehicle systems can warm the reserve fuel during operation. In the event that the tank is not vented, and if the fuel is sufficiently heated, the liquid fuel may become superheated and pose a splash hazard if the fuel cap is suddenly removed. Sudden depressurization of the superheated fluid will allow liquid fuel to rapidly flash into vapor. Depending on the fuel type, degree of superheating, tank geometry, and amount of fuel in the tank, a transient two-phase flow of flashing liquid can potentially erupt out of the tank. There is one historical precedent for which it was alleged that this is a reoccurring problem [1]. Research on the Consumer Product Safety Commission (CPSC) website yielded no examples of a recall initiated because of the geyser effect in a fuel tank [2]. A general internet search reveals anecdotal reports involving a variety of types of equipment [3,4,5]. Much of the information available in the public domain about these alleged incidents is substantially incomplete or unverified. In most of the instances reviewed, it could not be determined

Volume 14: Emerging Technologies; Engineering Management, Safety, Ethics, Society, and Education; Materials: Genetics to Structures, 2014

ABSTRACT The hazards from a boiling liquid expanding vapor explosion (BLEVE) include the formatio... more ABSTRACT The hazards from a boiling liquid expanding vapor explosion (BLEVE) include the formation of a blast wave and the projection of missiles. To understand the maximum work that can be obtained from a BLEVE, the authors have investigated in previous publications certain aspects of BLEVE behavior using exergy analysis. One of the key limitations in relating exergy calculations to more realistic behavior is the lack of knowledge of how the exergy of the explosion is partitioned into various types of work that occur in the BLEVE process. Some of these work terms include the formation and propagation of a shock wave, the strain work of vessel deformation and rupture into missiles, the initial kinetic energy of the missiles, and the surface work of aerosol droplet formation. In this paper we explore one of these work terms, the surface work performed in transforming the bulk liquid into aerosol droplets. The advantage of using exergy analysis to evaluate the maximum work of an explosion is that exergy is a state variable: its value depends only on the initial conditions of the high pressure fluid and the specification of the dead state. The methodology is illustrated for several pure component fluids. INTRODUCTION An explosion is a rapid release of energy that causes a blast wave [1]. The blast wave can perform work in the form of mechanical damage such as vessel ruptures, structural collapses, or the projection of missiles. The severity of the damage caused by an explosion can be correlated to the amount of mechanical work that the blast can perform. Exergy is a measure of the maximum work available from system. In a boiling liquid, expanding vapor explosion (BLEVE), the exergy is calculated as the difference between the initial state and the dead state of the fluid in the rupturing vessel. However, some of this work must be expended as strain work (rupturing the vessel) and surface work (creating aerosol droplets from the bulk liquid). In this paper we expand upon our previous work where we extended Crowl's analysis [2,3,4] to the BLEVE [5, 6, 1.7] as an alternative to traditional approaches [8]. In the background section we discuss the basic events of a BLEVE, introduce the exergy concept, and describe briefly the approaches taken by previous investigators. The next section presents an overview of select theoretical and experimental studies on aerosol droplet formation by both pressure atomization and explosive dispersal with an emphasis on predicting the resulting aerosol droplet diameter distribution. Following that discussion we analyze the surface work associated with aerosol droplet formation. Finally, we present sample calculations estimating the fraction of exergy that goes into surface work, and indicate areas for further development.

Molten sulfur is one of the most frequently transported hazardous materials (hazmat) in North Ame... more Molten sulfur is one of the most frequently transported hazardous materials (hazmat) in North America. Typically, molten sulfur is transported by rail tank cars or over-the-road tank trailers. According to the U.S. Department of Transportation Research and Special Programs Administration’s hazmat incident database, there have been 326 reported releases of molten sulfur in transportation between the years 1993 to 2003, inclusive. Some incident reports indicate that high levels of hydrogen sulfide gas were released during the initial stages of unloading preparation. In a few reported cases, the concentration of hydrogen sulfide was high enough to cause unloading personnel to lose consciousness, which then lead to further injury. A review of the Occupational Safety and Health Administration (OSHA) accident report database confirms that over the last twenty years there have been four reported fatalities from hydrogen sulfide exposure associated with molten sulfur containers. Over the la...

Over the last 25 years the chemical process industry has invested a great deal of effort to promo... more Over the last 25 years the chemical process industry has invested a great deal of effort to promote process safety and security in their production facilities. In that same time frame, the chemical supply chain has become increasingly more vulnerable to disruptions. Business factors such as reduced inventories (“lean manufacturing”), sole-source contracting, globalization, and aging transportation infrastructure have conspired to make supply chains extremely vulnerable to delays or interruptions in the flow of materials. The challenge of managing supply chain disruptions is complex since they can be caused by a broad array of events including accidents, natural hazards, and sabotage. Thus, while the threats to production capacity from hazards have been brought under a higher level of control, the potential frequency and severity of external hazards has actually increased. In this paper we illustrate how some of the tools developed for chemical process hazard analysis can be adapted ...

The automation of chemical processes has both positive and negative features. Computer automation... more The automation of chemical processes has both positive and negative features. Computer automation can be a powerful tool for safety management. On the other hand, it provides new opportunities for human error both in design and in operation. The interaction of process equipment, control systems, and operators can be complex. This is especially true with the discrete control of batch systems. In this paper we investigate an accident with an automatically controlled batch dryer that resulted in an explosion and fire. The batch dryer contained a heat transfer subsystem. The heat transfer subsystem consisted of a combustible oil circulated continuously in a closed loop. The purpose of the heat transfer subsystem was to maintain a plate heat exchanger at a constant temperature. The process dryer was programmed to dry a batch of material in contact with the slab by advancing through several stages of operation. The dryer was controlled by a supervisory control and data acquisition system ...

Frank-Kamenetskii thermal ignition theory has been used to model the self-heating behavior of sol... more Frank-Kamenetskii thermal ignition theory has been used to model the self-heating behavior of solids. The theory does not account for the effects of internal convection in the case of a porous body. A lignocellulosic solid (wood flour) experimental program was conducted to investigate the self-heating properties. The apparent kinetic parameters and physical parameters for the wood flour thermal ignition were developed from that study using the approach of Frank-Kamenetskii. The self-heating solid was modeled using FLUENT as a porous solid body with uniform thermal boundary conditions. Based upon comparing the density of the wood flour to solid wood, the porosity was calculated as 0.63 for the porous body with the balance consisting of air. The model was given a sensitivity analysis on permeability ranging from 10-6 m2 to 10-20 m2 (effectively impermeable) to investigate the effects on the self-heating behavior of the porous body. Changing the permeability was found to affect the loc...

Determining safe storage conditions for a self-heating material requires knowledge of the reactio... more Determining safe storage conditions for a self-heating material requires knowledge of the reaction kinetics governing its decomposition under potential storage conditions. Several thermal hazards analysis techniques are available, but most require kinetics analysis at a high temperature and micro-scale quantities. In contrast, isothermal calorimetry (i.e., isothermal oven tests) has proven to be a convenient method for conducting experiments with material quantities in the 0.1 to 1000 kilogram range at conditions more closely resembling the potential storage environment. The isothermal oven test protocol determines the critical temperature for several different sample sizes. The resulting data are then analyzed using the Frank-Kamenetskii variables to yield estimates for the activation energy and the pre-exponential factor. The classical Frank-Kamenetskii solution of the self-heating problem assumes that heat generation, described by zero order reaction kinetics, is balanced by heat...

Volume 9: Transportation Systems; Safety Engineering, Risk Analysis and Reliability Methods; Applied Stochastic Optimization, Uncertainty and Probability, 2011

A boiling liquid, expanding vapor explosion (BLEVE) occurs when a pressure vessel containing a su... more A boiling liquid, expanding vapor explosion (BLEVE) occurs when a pressure vessel containing a superheated liquid undergoes a catastrophic failure, resulting in a violent vaporization of the liquid. The exposure of a pressure vessel to a fire is a classic scenario that can result in a BLEVE. The thermomechanical exergy of a pressure vessel’s contents provides — by definition — an upper bound on the work that can be performed by the system during the explosion. By fixing the values of ambient pressure and temperature (i.e., the dead state), exergy can be interpreted as another thermodynamic property. This rigorous and unambiguous definition makes it ideal to estimate the maximum energy of explosions. The numerical value of exergy depends on the definition of the dead state. In this paper we examine the effect of different definitions for the dead state on the explosion energy value. We consider two applications of this method: the contribution of the vapor head-space to the explosive...

Process Safety Progress, 2014

ABSTRACT The treatment of hazardous waste poses some unique chemical reactivity hazard management... more ABSTRACT The treatment of hazardous waste poses some unique chemical reactivity hazard management challenges. Hazardous waste in the United States is regulated by the Resource Conservation and Recovery Act, typically due to potential environmental and health hazards. However, hazardous waste can also have chemical reactivity hazards associated with storage, handling, or mixing with other materials. The U.S. Environmental Protection Agency has been active in communicating chemical reactivity hazards to the regulated community and has identified numerous sources for additional information. The Center for Chemical Process Safety has also been very active in providing advisory materials and monographs on the safe management of chemical reactivity hazards. Other federal government agencies, such as the Chemical Safety Board and the Occupational Safety and Health Administration, have also taken up the call for increased awareness of the hazards of unintentional chemical reactions.Despite these efforts, history of incidents indicates that reactive chemical hazards associated with hazardous waste still go overlooked. In this article, we review hazardous waste incidents through case studies and public sector reports through the lens of chemical reactivity hazard management. In each incident, inadvertent heating resulted in an unintended chemical reaction, and sufficient information existed or could have been obtained to identify the hazards. © 2014 American Institute of Chemical Engineers Process Saf Prog, 2014

Process Safety Progress, 2014

This case study examines a succession of three separate fires which occurred in a period of 4 day... more This case study examines a succession of three separate fires which occurred in a period of 4 days at an agricultural chemical manufacturing facility. The facility was located in a small chemical park. The succession of fires illustrates the concept of the domino effect: the first fire caused the second fire, and the second fire caused the third. The final fire was responsible for the total destruction of two businesses and the interruption of a third business. Each fire involved the solid oxidizer sodium chlorate. Despite having manufactured agricultural chemicals for over 25 years, the owner and management of the facility had lost their sense of vulnerability to the hazards of sodium chlorate. The fundamental root cause of these fires was the facility owner's inadequate control of the hazards of sodium chlorate. Workers at the facility had little comprehension of the ability of sodium chlorate to cause organic materials to spontaneously ignite. Housekeeping at the facility was poor. And finally, too large of a quantity of sodium chlorate was stored inside the facility, and this large inventory of solid oxidizer was placed adjacent to combustible materials. Simple procedural safeguards would have been sufficient to prevent the ultimate property damage. V C 2014

The American Institute of Chemical Engineers (AIChE), the Chemical Safety Board (CSB), and the Oc... more The American Institute of Chemical Engineers (AIChE), the Chemical Safety Board (CSB), and the Occupational Safety and Health Administration (OSHA) have all emphasized the importance of advancing inherently safer design concepts into chemical process plants. Incident investigations offer an important opportunity to identify, evaluate, and correct potential shortcomings in the design, construction, operation, and maintenance of a chemical process unit that has experienced a release. This paper focuses on the inherently safer design principle of simplification. The case studies share the common theme of storing or handling liquids. Each case study illustrates how a design flaw led to unintended flow, reverse flow, or overfilling of a vessel which ultimately led to a fire, explosion, or hazardous release. Based on the incident investigation experiences of the authors, the paper illustrates how application of the simplification principle could have prevented these incidents.

Process Safety Progress, 2015

Process Safety and Environmental Protection, 2015

The 1984 Bhopal tragedy involved the toxic and reactive chemical methyl isocyanate (MIC). The eno... more The 1984 Bhopal tragedy involved the toxic and reactive chemical methyl isocyanate (MIC). The enormous human toll of this tragedy spurred the development of the concept of inherently safer design (ISD), and several published studies have since demonstrated the application of ISD concepts to the Bhopal process. In 2008, the U.S. Chemical Safety Board (CSB) investigated a fatal explosion at a chemical plant in West Virginia, for which a potential (unrealized) outcome was the loss-of-containment of the large inventory of MIC stored onsite. The CSB asked the National Academy of Sciences (NAS) to investigate the application of ISD concepts to the design of the West Virginia plant. The NAS study indicated that one of the primary difficulties in evaluating and choosing between ISD alternatives was the need to satisfy conflicting design objectives. The NAS panel suggested Multi-attribute utility theory (MAUT) as a basis for evaluating ISD alternatives, but they did not illustrate its use in this report. Here, we illustrate the use of MAUT as a decision analysis tool for evaluating ISD alternatives, and show that the MAUT technique is an effective tool for resolving ISD conflicts. We demonstrate how to use MAUT to evaluate ISD alternatives by formulating utility functions and weights for the decision objectives. We also examine how the final ranking of alternatives varies with the weights.

Following the work of Crowl on calculating the energy of explosions using exergy (thermodynamic a... more Following the work of Crowl on calculating the energy of explosions using exergy (thermodynamic availability), we examine the explosion energy of boiling liquid, expanding vapor explosions (BLEVEs). A number of investigators have proposed schemes for calculating the maximum work that a BLEVE can perform on its surroundings. Their proposed evaluation schemes yield varying results because they depend significantly on the precise specification of the thermodynamic path taken by the vaporizing, expanding mass. We demonstrate how to evaluate the maximum theoretical work associated with a BLEVE as a function of the fluid's thermodynamic properties and its equation of state. We consider two specific forms of BLEVE: nonreactive and reactive (combusting) fluids. Finally, we give numerical examples to compare the availability of a BLEVE with some of the proposed schemes suggested by others. The advantage of using exergy analysis to evaluate the maximum work of a BLEVE is the rigorous and ...

Forensic Engineering 2012, 2012

This paper describes the investigation of a chlorine gas release at a public swimming pool. Over ... more This paper describes the investigation of a chlorine gas release at a public swimming pool. Over one hundred patrons were exposed to the chlorine gas release. The chlorine gas was generated by the inadvertent mixing of sodium hypochlorite solution and hydrochloric acid. The accident investigation concluded that the release was caused by a combination of maintenance and design errors. The maintenance error was procedural: on the second day of the maintenance task the contractor did not follow the standard lockout-tagout (LOTO) procedure for isolating the chemical feeder. If he had followed the LOTO procedure, the accident would have been prevented. The design defect was related to the control logic and the physical arrangement of the equipment under control. The causal factors of the accident are discussed and lessons learned are offered to prevent a recurrence of similar accidents. A key feature of this accident was the failure to properly isolate the automatic control system during routine maintenance.

Mary Kay O'Connor Process Safety Center, 2000

Due to the large quantities of hazardous chemicals, an accident at a chemical facility can have s... more Due to the large quantities of hazardous chemicals, an accident at a chemical facility can have serious consequences. The owner/operator of a chemical facility has a great interest in investigating the cause of any accident as a basis for corrective action. The lessons learned from an accident investigation can be instrumental in preventing a recurrence. However, there can be many other stakeholders in a chemical accident, including regulatory authorities (e.g., the Occupational Safety and Health Administration (OSHA) and the United States Environmental Protection Agency (USEPA)) and advisory agencies (e.g., the Chemical Safety and Hazard Investigation Board (CSB) and the National Transportation Safety Board (NTSB)). How well do these organizations investigate chemical accidents? What can we learn from their recent investigations? This paper critically examines investigations conducted by OSHA, USEPA, CSB and NTSB. The scope of this investigation is restricted to a sample of published reports available during the five-year period 1995-1999. The survey of reports includes an analysis of the chemicals involved in the accidents as well as the types of equipment and work activities. Consideration is given to the identification of causal factors and the proposed corrective actions. The analytical tools used in the investigations are compared and the overall methodology is assessed. Finally, the lessons learned from these investigations are reviewed and compared with case studies drawn from the chemical process safety literature.

Journal of Loss Prevention in the Process Industries, 2021

One of the more obvious consequences of a dust deflagration inside process equipment or a structu... more One of the more obvious consequences of a dust deflagration inside process equipment or a structure is the mechanical damage caused by shock (compression) waves. This overpressure damage is revealed through the displacement of equipment, the outward deformation or rupture of enclosures constructed of ductile materials, or the projection of missiles. However, a different type of damage is sometimes observed in the ductwork connecting process equipment. In particular, the ductwork is collapsed as if it were subjected to an external, rather than an internal pressure. The phenomenon that causes this collapse of thin-walled conduit is a gas dynamic process called an expansion wave. When a dust deflagration travels through a conduit, it accelerates and causing a rise in pressure. When the dust deflagration is vented (say through a deflagration vent), the discharge of the high pressure combustion products causes the formation of an expansion wave that travels in the reverse direction from the vent backwards. The expansion wave causes the pressure in the ductwork to fall below atmospheric pressure. The sub-atmospheric pressure, in turn, causes the ductwork to fail by buckling. In this study, we examine the gas dynamics of the expansion wave, demonstrate how to calculate the degree of pressure drop caused by the expansion wave, and illustrate the concept with case studies of dust explosions.

Journal of Loss Prevention in the Process Industries, 2019

There are many sources of mechanical energy in agricultural processing facilities. This is partic... more There are many sources of mechanical energy in agricultural processing facilities. This is particularly true when milling is performed. If mechanical energy turns into sufficient thermal energy (heat), it can cause material to smolder. If that smoldering material is fluidized, e.g., through pneumatic conveyance or air/material separation, a deflagration may occur. A case study of an explosion at a wheat milling facility is used to illustrate the hazard. Fugitive grain dust played no role in the event, and no secondary explosion occurred. Although the equipment involved in this incident was vented in accordance with NFPA guidance, a significant portion of the facility was destroyed in the explosion. The severity of the resulting explosion damage resulted, in part, due to the initial conditions assumed in this typical explosion vent design, which did not consider the effects of flame acceleration and pressure piling upstream of the vented filter house. First, we present a basic overview of milling operations, particularly equipment involved in material separation and size reduction. Then we detail the investigation of this incident. Equipment damage, witness observations, and material properties are used to determine the cause. Finally, we discuss lessons learned. Particular attention is paid to milling safeguards and the effects of flame acceleration in the context of the damage observed.

Process Safety Progress, 2018

Ignition by electrostatic discharge of clean flammable gas, such as natural gas, being released t... more Ignition by electrostatic discharge of clean flammable gas, such as natural gas, being released to the atmosphere during blowdown operations is unlikely. However, the presence of foreign material in the form of solid particles or liquid droplets changes the risk level significantly. The discharge of a flammable gas stream with a cloud of foreign material poses a potential electrostatic hazard, even if the piping system and associated equipment is otherwise bonded and grounded. The foreign material may be capable of accumulating sufficient electrostatic potential to ignite the flammable gas. There have been several documented incidents where ignition has occurred during a flammable gas blowdown. In some instances, gas lines were being cleaned, while in others, the blowdown was completed as a safety measure for another process. This article will focus on a case study where a stream of flammable gas was ignited during a blowdown and an obvious ignition source (other than electrostatic discharge) was not present, but foreign material was observed.

Process Safety Progress, 2018

Incorporating inherently safer design (ISD) into a process safety program can benefit a site's ov... more Incorporating inherently safer design (ISD) into a process safety program can benefit a site's overall process safety program. However, ISD solutions are rarely capable of being implemented without consideration of various tradeoffs associated with other critical operating factors at a plant. Critics have often accused companies of failing to implement ISD solely on the basis of cost, often neglecting other factors that must be accounted for in the decision. Multiattribute decisions are difficult to resolve, but there are tools available to assist the decision maker. One such tool that can be applied to provide insight into the implementation of ISD solutions is multiattribute utility theory (MAUT). MAUT is a structured approach that evaluates the strengths and weaknesses of competing solutions for a problem with multiple objectives. In this article, the concept of MAUT will be explained. Then MAUT analysis will be applied to three case studies where investigators have recommended incorporating ISD or technology into a process. Using MAUT analysis, the benefit of the proposed design change will be evaluated in a systematic, semiquantitative methodology that will demonstrate how the tools can help facility personnel understand and characterize the benefits of ISD.

Volume 14: Emerging Technologies; Engineering Management, Safety, Ethics, Society, and Education; Materials: Genetics to Structures, 2014

ABSTRACT This paper explores an infrequently encountered hazard associated with liquid fuel tanks... more ABSTRACT This paper explores an infrequently encountered hazard associated with liquid fuel tanks on gasoline-powered equipment using non-vented fuel caps. Depending on the location of fuel reserve tanks, waste heat from the engine or other vehicle systems can warm the fuel during operation. In the event that the fuel cap is not vented and if the fuel is sufficiently heated, the liquid fuel may become superheated and pose a splash hazard if the fuel cap is suddenly removed. Accident reports often describe the ejection of liquid from the fuel tank opening as a geyser. This geyser is a transient, two-phase flow, vertical jet of flashing liquid. This could create a fire hazard as the geyser could result in splashing flammable liquid onto any bystanders. Many fuel tank systems are vented to ambient through the fuel tank cap and, in addition, may incorporate other features that contribute to pressure relief. Venting of the pressurized vapor inhibits the vapor-liquid mixture in the fuel tank from achieving thermodynamic equilibrium, thus preventing the formation of a superheated liquid. It has been empirically determined that flashing two-phase flow can be prevented by keeping the fuel tank pressure below 1.5 psig. However, if the cap is not vented or vents at a lesser rate than the rate of liquid vaporization, pressure in the tank can rise and the flammable liquid can become superheated. This phenomenon is explored here to facilitate a better understanding of how the hazard is created. The nature of the hazard is explained using thermodynamic concepts. The differences in behavior between a closed system and an open system are discussed and then illustrated through experimental results obtained from two sources: experiments with externally heated fuel containers and operation of a gasoline-powered riding lawn mower. The role of the vented fuel cap in preventing the geyser phenomenon is demonstrated. INTRODUCTION Gasoline powered equipment has remained a centerpiece of the industrialized world since scaled manufacturing began in the early 20 th century. The fundamental makeup of these systems has not changed in that a reserve fuel tank is mounted on the equipment and gradually depleted during operation as fuel is withdrawn for combustion in the engine. To provide for continued operation, the fuel tank must intermittently be refilled, which requires accessing the tank's interior by removal of a cap or other tank closure. This paper examines a potential hazard associated with superheating gasoline in a closed system. Depending on the location of fuel reserve tanks, waste heat from the engine or other vehicle systems can warm the reserve fuel during operation. In the event that the tank is not vented, and if the fuel is sufficiently heated, the liquid fuel may become superheated and pose a splash hazard if the fuel cap is suddenly removed. Sudden depressurization of the superheated fluid will allow liquid fuel to rapidly flash into vapor. Depending on the fuel type, degree of superheating, tank geometry, and amount of fuel in the tank, a transient two-phase flow of flashing liquid can potentially erupt out of the tank. There is one historical precedent for which it was alleged that this is a reoccurring problem [1]. Research on the Consumer Product Safety Commission (CPSC) website yielded no examples of a recall initiated because of the geyser effect in a fuel tank [2]. A general internet search reveals anecdotal reports involving a variety of types of equipment [3,4,5]. Much of the information available in the public domain about these alleged incidents is substantially incomplete or unverified. In most of the instances reviewed, it could not be determined

Volume 14: Emerging Technologies; Engineering Management, Safety, Ethics, Society, and Education; Materials: Genetics to Structures, 2014

ABSTRACT The hazards from a boiling liquid expanding vapor explosion (BLEVE) include the formatio... more ABSTRACT The hazards from a boiling liquid expanding vapor explosion (BLEVE) include the formation of a blast wave and the projection of missiles. To understand the maximum work that can be obtained from a BLEVE, the authors have investigated in previous publications certain aspects of BLEVE behavior using exergy analysis. One of the key limitations in relating exergy calculations to more realistic behavior is the lack of knowledge of how the exergy of the explosion is partitioned into various types of work that occur in the BLEVE process. Some of these work terms include the formation and propagation of a shock wave, the strain work of vessel deformation and rupture into missiles, the initial kinetic energy of the missiles, and the surface work of aerosol droplet formation. In this paper we explore one of these work terms, the surface work performed in transforming the bulk liquid into aerosol droplets. The advantage of using exergy analysis to evaluate the maximum work of an explosion is that exergy is a state variable: its value depends only on the initial conditions of the high pressure fluid and the specification of the dead state. The methodology is illustrated for several pure component fluids. INTRODUCTION An explosion is a rapid release of energy that causes a blast wave [1]. The blast wave can perform work in the form of mechanical damage such as vessel ruptures, structural collapses, or the projection of missiles. The severity of the damage caused by an explosion can be correlated to the amount of mechanical work that the blast can perform. Exergy is a measure of the maximum work available from system. In a boiling liquid, expanding vapor explosion (BLEVE), the exergy is calculated as the difference between the initial state and the dead state of the fluid in the rupturing vessel. However, some of this work must be expended as strain work (rupturing the vessel) and surface work (creating aerosol droplets from the bulk liquid). In this paper we expand upon our previous work where we extended Crowl's analysis [2,3,4] to the BLEVE [5, 6, 1.7] as an alternative to traditional approaches [8]. In the background section we discuss the basic events of a BLEVE, introduce the exergy concept, and describe briefly the approaches taken by previous investigators. The next section presents an overview of select theoretical and experimental studies on aerosol droplet formation by both pressure atomization and explosive dispersal with an emphasis on predicting the resulting aerosol droplet diameter distribution. Following that discussion we analyze the surface work associated with aerosol droplet formation. Finally, we present sample calculations estimating the fraction of exergy that goes into surface work, and indicate areas for further development.

Molten sulfur is one of the most frequently transported hazardous materials (hazmat) in North Ame... more Molten sulfur is one of the most frequently transported hazardous materials (hazmat) in North America. Typically, molten sulfur is transported by rail tank cars or over-the-road tank trailers. According to the U.S. Department of Transportation Research and Special Programs Administration’s hazmat incident database, there have been 326 reported releases of molten sulfur in transportation between the years 1993 to 2003, inclusive. Some incident reports indicate that high levels of hydrogen sulfide gas were released during the initial stages of unloading preparation. In a few reported cases, the concentration of hydrogen sulfide was high enough to cause unloading personnel to lose consciousness, which then lead to further injury. A review of the Occupational Safety and Health Administration (OSHA) accident report database confirms that over the last twenty years there have been four reported fatalities from hydrogen sulfide exposure associated with molten sulfur containers. Over the la...

Over the last 25 years the chemical process industry has invested a great deal of effort to promo... more Over the last 25 years the chemical process industry has invested a great deal of effort to promote process safety and security in their production facilities. In that same time frame, the chemical supply chain has become increasingly more vulnerable to disruptions. Business factors such as reduced inventories (“lean manufacturing”), sole-source contracting, globalization, and aging transportation infrastructure have conspired to make supply chains extremely vulnerable to delays or interruptions in the flow of materials. The challenge of managing supply chain disruptions is complex since they can be caused by a broad array of events including accidents, natural hazards, and sabotage. Thus, while the threats to production capacity from hazards have been brought under a higher level of control, the potential frequency and severity of external hazards has actually increased. In this paper we illustrate how some of the tools developed for chemical process hazard analysis can be adapted ...

The automation of chemical processes has both positive and negative features. Computer automation... more The automation of chemical processes has both positive and negative features. Computer automation can be a powerful tool for safety management. On the other hand, it provides new opportunities for human error both in design and in operation. The interaction of process equipment, control systems, and operators can be complex. This is especially true with the discrete control of batch systems. In this paper we investigate an accident with an automatically controlled batch dryer that resulted in an explosion and fire. The batch dryer contained a heat transfer subsystem. The heat transfer subsystem consisted of a combustible oil circulated continuously in a closed loop. The purpose of the heat transfer subsystem was to maintain a plate heat exchanger at a constant temperature. The process dryer was programmed to dry a batch of material in contact with the slab by advancing through several stages of operation. The dryer was controlled by a supervisory control and data acquisition system ...

Frank-Kamenetskii thermal ignition theory has been used to model the self-heating behavior of sol... more Frank-Kamenetskii thermal ignition theory has been used to model the self-heating behavior of solids. The theory does not account for the effects of internal convection in the case of a porous body. A lignocellulosic solid (wood flour) experimental program was conducted to investigate the self-heating properties. The apparent kinetic parameters and physical parameters for the wood flour thermal ignition were developed from that study using the approach of Frank-Kamenetskii. The self-heating solid was modeled using FLUENT as a porous solid body with uniform thermal boundary conditions. Based upon comparing the density of the wood flour to solid wood, the porosity was calculated as 0.63 for the porous body with the balance consisting of air. The model was given a sensitivity analysis on permeability ranging from 10-6 m2 to 10-20 m2 (effectively impermeable) to investigate the effects on the self-heating behavior of the porous body. Changing the permeability was found to affect the loc...

Determining safe storage conditions for a self-heating material requires knowledge of the reactio... more Determining safe storage conditions for a self-heating material requires knowledge of the reaction kinetics governing its decomposition under potential storage conditions. Several thermal hazards analysis techniques are available, but most require kinetics analysis at a high temperature and micro-scale quantities. In contrast, isothermal calorimetry (i.e., isothermal oven tests) has proven to be a convenient method for conducting experiments with material quantities in the 0.1 to 1000 kilogram range at conditions more closely resembling the potential storage environment. The isothermal oven test protocol determines the critical temperature for several different sample sizes. The resulting data are then analyzed using the Frank-Kamenetskii variables to yield estimates for the activation energy and the pre-exponential factor. The classical Frank-Kamenetskii solution of the self-heating problem assumes that heat generation, described by zero order reaction kinetics, is balanced by heat...

Volume 9: Transportation Systems; Safety Engineering, Risk Analysis and Reliability Methods; Applied Stochastic Optimization, Uncertainty and Probability, 2011

A boiling liquid, expanding vapor explosion (BLEVE) occurs when a pressure vessel containing a su... more A boiling liquid, expanding vapor explosion (BLEVE) occurs when a pressure vessel containing a superheated liquid undergoes a catastrophic failure, resulting in a violent vaporization of the liquid. The exposure of a pressure vessel to a fire is a classic scenario that can result in a BLEVE. The thermomechanical exergy of a pressure vessel’s contents provides — by definition — an upper bound on the work that can be performed by the system during the explosion. By fixing the values of ambient pressure and temperature (i.e., the dead state), exergy can be interpreted as another thermodynamic property. This rigorous and unambiguous definition makes it ideal to estimate the maximum energy of explosions. The numerical value of exergy depends on the definition of the dead state. In this paper we examine the effect of different definitions for the dead state on the explosion energy value. We consider two applications of this method: the contribution of the vapor head-space to the explosive...

Process Safety Progress, 2014

ABSTRACT The treatment of hazardous waste poses some unique chemical reactivity hazard management... more ABSTRACT The treatment of hazardous waste poses some unique chemical reactivity hazard management challenges. Hazardous waste in the United States is regulated by the Resource Conservation and Recovery Act, typically due to potential environmental and health hazards. However, hazardous waste can also have chemical reactivity hazards associated with storage, handling, or mixing with other materials. The U.S. Environmental Protection Agency has been active in communicating chemical reactivity hazards to the regulated community and has identified numerous sources for additional information. The Center for Chemical Process Safety has also been very active in providing advisory materials and monographs on the safe management of chemical reactivity hazards. Other federal government agencies, such as the Chemical Safety Board and the Occupational Safety and Health Administration, have also taken up the call for increased awareness of the hazards of unintentional chemical reactions.Despite these efforts, history of incidents indicates that reactive chemical hazards associated with hazardous waste still go overlooked. In this article, we review hazardous waste incidents through case studies and public sector reports through the lens of chemical reactivity hazard management. In each incident, inadvertent heating resulted in an unintended chemical reaction, and sufficient information existed or could have been obtained to identify the hazards. © 2014 American Institute of Chemical Engineers Process Saf Prog, 2014

Process Safety Progress, 2014

This case study examines a succession of three separate fires which occurred in a period of 4 day... more This case study examines a succession of three separate fires which occurred in a period of 4 days at an agricultural chemical manufacturing facility. The facility was located in a small chemical park. The succession of fires illustrates the concept of the domino effect: the first fire caused the second fire, and the second fire caused the third. The final fire was responsible for the total destruction of two businesses and the interruption of a third business. Each fire involved the solid oxidizer sodium chlorate. Despite having manufactured agricultural chemicals for over 25 years, the owner and management of the facility had lost their sense of vulnerability to the hazards of sodium chlorate. The fundamental root cause of these fires was the facility owner's inadequate control of the hazards of sodium chlorate. Workers at the facility had little comprehension of the ability of sodium chlorate to cause organic materials to spontaneously ignite. Housekeeping at the facility was poor. And finally, too large of a quantity of sodium chlorate was stored inside the facility, and this large inventory of solid oxidizer was placed adjacent to combustible materials. Simple procedural safeguards would have been sufficient to prevent the ultimate property damage. V C 2014

The American Institute of Chemical Engineers (AIChE), the Chemical Safety Board (CSB), and the Oc... more The American Institute of Chemical Engineers (AIChE), the Chemical Safety Board (CSB), and the Occupational Safety and Health Administration (OSHA) have all emphasized the importance of advancing inherently safer design concepts into chemical process plants. Incident investigations offer an important opportunity to identify, evaluate, and correct potential shortcomings in the design, construction, operation, and maintenance of a chemical process unit that has experienced a release. This paper focuses on the inherently safer design principle of simplification. The case studies share the common theme of storing or handling liquids. Each case study illustrates how a design flaw led to unintended flow, reverse flow, or overfilling of a vessel which ultimately led to a fire, explosion, or hazardous release. Based on the incident investigation experiences of the authors, the paper illustrates how application of the simplification principle could have prevented these incidents.

Process Safety Progress, 2015

Process Safety and Environmental Protection, 2015

The 1984 Bhopal tragedy involved the toxic and reactive chemical methyl isocyanate (MIC). The eno... more The 1984 Bhopal tragedy involved the toxic and reactive chemical methyl isocyanate (MIC). The enormous human toll of this tragedy spurred the development of the concept of inherently safer design (ISD), and several published studies have since demonstrated the application of ISD concepts to the Bhopal process. In 2008, the U.S. Chemical Safety Board (CSB) investigated a fatal explosion at a chemical plant in West Virginia, for which a potential (unrealized) outcome was the loss-of-containment of the large inventory of MIC stored onsite. The CSB asked the National Academy of Sciences (NAS) to investigate the application of ISD concepts to the design of the West Virginia plant. The NAS study indicated that one of the primary difficulties in evaluating and choosing between ISD alternatives was the need to satisfy conflicting design objectives. The NAS panel suggested Multi-attribute utility theory (MAUT) as a basis for evaluating ISD alternatives, but they did not illustrate its use in this report. Here, we illustrate the use of MAUT as a decision analysis tool for evaluating ISD alternatives, and show that the MAUT technique is an effective tool for resolving ISD conflicts. We demonstrate how to use MAUT to evaluate ISD alternatives by formulating utility functions and weights for the decision objectives. We also examine how the final ranking of alternatives varies with the weights.

Following the work of Crowl on calculating the energy of explosions using exergy (thermodynamic a... more Following the work of Crowl on calculating the energy of explosions using exergy (thermodynamic availability), we examine the explosion energy of boiling liquid, expanding vapor explosions (BLEVEs). A number of investigators have proposed schemes for calculating the maximum work that a BLEVE can perform on its surroundings. Their proposed evaluation schemes yield varying results because they depend significantly on the precise specification of the thermodynamic path taken by the vaporizing, expanding mass. We demonstrate how to evaluate the maximum theoretical work associated with a BLEVE as a function of the fluid's thermodynamic properties and its equation of state. We consider two specific forms of BLEVE: nonreactive and reactive (combusting) fluids. Finally, we give numerical examples to compare the availability of a BLEVE with some of the proposed schemes suggested by others. The advantage of using exergy analysis to evaluate the maximum work of a BLEVE is the rigorous and ...

Forensic Engineering 2012, 2012

This paper describes the investigation of a chlorine gas release at a public swimming pool. Over ... more This paper describes the investigation of a chlorine gas release at a public swimming pool. Over one hundred patrons were exposed to the chlorine gas release. The chlorine gas was generated by the inadvertent mixing of sodium hypochlorite solution and hydrochloric acid. The accident investigation concluded that the release was caused by a combination of maintenance and design errors. The maintenance error was procedural: on the second day of the maintenance task the contractor did not follow the standard lockout-tagout (LOTO) procedure for isolating the chemical feeder. If he had followed the LOTO procedure, the accident would have been prevented. The design defect was related to the control logic and the physical arrangement of the equipment under control. The causal factors of the accident are discussed and lessons learned are offered to prevent a recurrence of similar accidents. A key feature of this accident was the failure to properly isolate the automatic control system during routine maintenance.