Five out of the 20 largest losses in the hydrocarbon industries were caused by a vapour cloud explosion. This paper introduces a new method now commonly referred to as the baker. This paper surveys accidental explosions that have occurred over the past 40 years. What is the abbreviation for unconfined vapour cloud explosion. Preliminary result on unconfined vapor cloud explosion. If ignited, the flame speed may accelerate to high velocities and produce significant blast overpressure. Evaluating characteristics of vapour cloud explosions. Vapor cloud explosions this chapter discusses vapor cloud explosions in detail.
It has been updated to include advanced modeling technology, especially with respect to vapor cloud modeling and the use of computational fluid dynamics. The explosive power of a vapor cloud can be expressed as an equivalent cxplosivc chargc whosc. Astonishingly high pressure can result from an unconfined vapor cloud explosion. The ignition source of the cloud was likely an emergency pump house. Unconfined vapor cloud explosion how is unconfined vapor cloud explosion abbreviated. A flame must propagate at a considerable speed to generate blast. A new perspective a modern perspective on the problem of vapor cloud and explosions is given. Guidelines for evaluating the characteristics of vapor. Such accidents are commonly named vapor cloud explosions vce. Vapour clould explosion vce for consequence and risk studies. Advancements in the prediction of blast damage due to vapour cloud explosions hans boot.
In december 1999, there was a natural gas explosion which completely destroyed one house and severely damaged four other houses in larkhall, south lanarkshire. The warehouse explosion became the powerful initiator for the explosion of the unconfined vapor cloud surrounding the warehouse. Significant advances in our fundmental understanding of detonation and flame acceleration have occurred in the last decade. Phase i included an analytical evaluation of the possible magnitude and damage potential of a spill of lng. Water curtains enhance lng vapor cloud dispersion and reduce the vapor cloud exclusion zone effectively, if properly designed icheme, 2007. An analysis of a vapor cloud explosion november 2006 explosion at caiarnel in danvers, massachusetts on november 22, 2006, at approximately 2. Tno model requires selection of one of the two possible explosive yields. Particular emphasis is placed on the important practical problem of detonation hazards. What is the abbreviation for vapour cloud explosion. Visit the rr11 report pdf portable document format hse. It proposes a model structure for the analysis of vapor cloud explosion risks to. The potential explosion hazard of a vapor cloud can bc quantified as king ils cxplosivc power upon ignition.
Numerical and experimental study of vapor cloud explosions. Chemical safety and hazard investigation board washington, d. Tnt equivalent model requires the specification of explosive yield. Major accidents such as buncefield, texas city and, more recently, at the amuay refinery in punto fijo venezuela, have focused attention on assessing the effects of vapour cloud explosion vce on assets such as buildings and process equipment, as well as people. Effectiveness of ventilation or barrier effects through air movement has been shown for control of vapor clouds in several studies. Experimental results on vce deflagration under unconfined conditions with obstacles low congestion 129. Guidelines for vapor cloud explosion, pressure vessel. Topics discussed include prevention of vapor cloud formation, reduction of vapor clouds, control of vapor clouds, and preventing or controlling their ignition. Vce abbreviation stands for vapour cloud explosion. Unconfined vapour cloud explosions gugan, keith on. Vapor cloud explosion analysis of onshore petrochemical. Owneroperators of chemical processing and petroleum refining sites often ask whether unconfined hydrogen vapor cloud explosions vces can actually occur.
The effectiveness of water curtains depends on its own characteristics and extrinsic parameters, such as gas properties, cloud features, wind speed, and atmospheric stability. The evaluation of cause from blast damage patterns is usually quite difficult, and in the case of unconfined vapor cloud explosions the mechanisms which led to significant blast overpressures are not understood at the present time. For these and other reasons, vapor cloud explosion risk analysis models are required to measure the potential explosive power of the flammable materials present in a process unit. The fuelair explosive fae is one of the bestknown types. These methods have been viewed as impractical in some tests. Vapor scrubbing or vapor phase reactions were not practical or effective except for anhydrousammonia 7664417 sorption by water sprays. The development of an unconfined vapor cloud explosion. Unconfined vapor cloud explosions also known as vapor cloud explosions in open air often result when accidental releases of vapors or gases to the atmosphere are ignited. Vapor cloud explosion blast modelling experimental. Confined vapor cloud explosion investigation board, u.
This question normally arises during the course of a consequence. Strehlow method for estimating pressure and impulse generated by vapor cloud explosions. This question normally arises in the course of a consequencebased facility siting study fss or a quantitative risk assessment qra. Vapor cloud explosion vce and boiling liquid expanding vapour explosion bleve, as also briefly discussed. Phase ii consisted of shock tube tests and tests in thin film hemispheres to evaluate potential transition from deflagration to detonation in unconfined clouds of flammable gases. Are unconfined hydrogen vapor cloud explosions credible. The upper levels of the propane vapor cloud mix with oxygen and are highly combustible.
Strehlow department of aeronautical and astronautical engineering, university of illinois at urbanachampaign the explosion of unconfined vapor clouds produced by the dispersion of flammable liquid or vapor spills is becoming a serious problem, mainly because of the increased size of the spills in. Unconfined vapor cloud explosion how is unconfined vapor. The regulation does not provide for consideration of boiling liquid expanding vapor explosions bleves or unconfined vapor cloud explosion uvce hazards, although the proposed terminal is designed to import lng containing natural gas liquids ngl in amounts sufficient to raise serious questions about the potential for uvces following. Results of experiments under unconfined conditions without obstacles 126 table 6. Strehlows blast curves and concepts from the multi. Final report to cpsd re long beach lng terminal 91405. This phenomenon also has been referred to as an unconfined vapor air explosion or unconfined vapor cloud. An unconfined vapor cloud explosion in a processing plant can involve partly. The blast from the explosion injured ten community members, damaged or destroyed more than. Unconfined vaporcloud explosionsan overview sciencedirect. Vapor cloud explosion study transportation research board. Development of a vapor cloud explosion risk analysis tool. Methane and propane would be considered as a gas but fuels such as gasoline, hexane, and cyclohexane are liquids which can vaporize forming a vapor cloud. Vapor cloud explosion analysis of onshore petrochemical facilities p.
Unconfined vaporcloud explosionsman overview roger a. Large vapour cloud explosions, with particular reference to that at. Brewerton, gexcon as abstract the paper describes an approach to predicting gas explosion loads and response which has been. The implications of the incident for the assessment of vapour cloud explosion hazards. This guide provides an overview of methods for estimating the characteristics of vapor cloud explosions, flash fires, and boilingliquidexpandingvapor explosions bleves for practicing engineers. The explosion of unconfined vapor clouds produced by the dispersion of flammable liquidor vapor spills is becoming a serious problem, mainly because of the increased size of the spills in recent years. Control of unconfined vapor clouds by fire department. Energy method for determination of explosion energy are applied in.
The explosion of unconfined vapor clouds produced by the dispersion of flammable liquidor vapor spills is becoming a serious problem, mainly because of the. Minimum flammable mass for vapor cloud explosions 4. Search for library items search for lists search for contacts search for a library. A question is frequently raised by owneroperators of chemical processing and refinery sites as to whether unconfined hydrogen vapor cloud explosions can actually occur.
This type of explosion is usually the result of a flammable gas spill. Workshop on unconfined vapor cloud explosions american. Vapor cloud explosion modeling estimated maximum loss of. A computational fluid dynamics cfd simulation of vapor cloud dispersion and ignition and fireball formation the video is shown at three different display rates. Uvce abbreviation stands for unconfined vapour cloud explosion. Pdf the potential for vapour cloud explosions lessons from the. However, this vapor cloud explosion was not a typical unconfined aerial explosion ignited by a spark or flame. This technology can be used on existing facilities but implies the installation of a water deluge system. Uvce unconfined vapour cloud explosion all acronyms. One example is deflagration of a vaporair mixture in an unconfined volume, which is commonly called an unconfined vapor cloud explosion. Overfilling of one of the storage tanks caused a release of 300 tons of unleaded gasoline and created a very large vapor cloud 120,000 m2. A thermobaric weapon, aerosol bomb, or vacuum bomb, is a type of explosive that uses oxygen from the surrounding air to generate a hightemperature explosion, and in practice the blast wave typically produced by such a weapon is of a significantly longer duration than that produced by a conventional condensed explosive. Project lfl cloud on congestion area explosion region red contour determines %confined and flame. Largescale experiments show that maximum explosion overpressures generated by vapour cloud explosions in a congested area may be reduced by a factor of 20 or more maximum overpressures of 10 bar or more were reduced to 0.
Chemical reactions typically occur under the extreme high pressure and temperature of the processing areas, whereas a vapor cloud explosion vce occurs when the release of a large volume of flammable gas or vapor mixes with air and finds its ignition source in a. As described in chapter 2, a vapor cloud explosion is the result of a release of flammable material in the atmosphere, a subsequent dispersion phase, and, after some delay, an ignition of the vapor cloud. Methods for finding the flammable mass in unconfined vapor clouds. On december 11, 1998, there was a gas explosion in st. Confined vapor cloud explosion 10 injured, and 24 houses and six businesses destroyed electronic resource. Values of the lower and upper flammable limits for a particular flammable gas or vapor depend on the oxidant and inert gas in the mixture, as well as the mixture. Flammable gases and vapors can produce an explosion when they are ignited while at a concentration between their lower and upper flammable limits, usually in a confined volume. Guidelines for evaluating the characteristics of vapor cloud explosions, guidelines for implementing process safety management systems. Confined vapor cloud explosion 10 injured, and 24 houses. Instead, pan of the cloud entered a warehouse and was ignited by a spark.
Request pdf preliminary result on unconfined vapor cloud explosion using vertical tube on hot surface the unconfined vapor cloud explosion uvce is. Use of water in emergency situations involving release of hazardous materials was discussed and a bibliography provided of major relevant technical articles. Presently, the belief is gaining ground that it is hardly possible to detonate an unconfined vapor cloud, originating from an accidental release of hydrocarbons in. Lewis ici mond division, northwich, cheshire summary in this paper, the effects of a release of fuel are shown to vary considerably, ranging from a non ignition to a violent aerial explosion or quasidetonation. To estimate overpressure which results from vapor cloud explosions is often part of a risk assessment. Unconfined vapor cloud explosion explosion combustion. Owneroperators of chemical processing and petroleum refining sites often ask whether unconfined hydrogen vapor cloud explosions vces. Explosions are a complicated physical phenomenon which science continues to investigate. Estimating the flammable mass of a vapor cloud wiley. The explosion destroyed a significant section of the depot and caused widespread damage to homes and businesses surrounding the site.
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