Boiling Liquid Expanding Vapor Explosion Research Articles

Forensic Engineering Investigation Of Hot Water Boiler And Heater Relief Valve Failures

Heating Systems And Hot Water Heaters In Residential Structures Are Often Neglected In Regards To Proper Maintenance And Repair. Although All Manufacturers Recommend Annual Preventative Maintenance On Water Heaters, Furnaces And Boilers, Oftentimes These Appliances Are Not Maintained In Accordance With Manufacturer Or Industry Maintenance Directives And Are Not Seen By Professional Servicemen Until After A Failure Occurs. Forgoing Preventative Maintenance Oftentimes Allows Equipment Failures And Resulting Consequences Such As Loss Of Heat, Soot, And Water Damage. Additionally, The Lack Of Maintenance Also Invites The Possibility Of More Severe Consequences Including Carbon Monoxide Poisonings, Fires, And More Commonly In Water Heaters And Forced Hot Water Or Ydronicheating Systems, Pressure Vessel Explosions. Short Of A Gas Or Propane Leak, The Most Severe Type Of Heating Appliance Malfunction Is Due To A Pressure Vessel Explosion Or Bleve (Boiling Liquid Expanding Vapor Explosion) Which Can Cause Severe Building Damage, As Well As Personal Injury. This Paper Identifies The System Components That Commonly Fail And Go Un-Noticed By Building Occupants, As Well As Service Personnel. This Paper Will Also Detail Typical Damage Caused By The Release

Parametric approach of the domino effect for structural fragments

More specific and accurate probabilistic models of the numbers of fragments generated respectively by Boiling Liquid Expanding Vapor Explosions (BLEVEs), Mechanical Explosions (MEs), Confined Explosions (CEs), and Runaway Reactions (RRs) of a horizontal cylindrical vessel were developed using the maximum entropy principle based on historical accident data. The theoretical results from the four probability density functions were compared to the observed data, and the numbers of fragments followed discrete exponential distributions in the interval [1, 9]. Beside the summary of the probabilistic distributions of the other random variables in the process of fragment projection, the effects on the fragment trajectory and target terms were investigated using a parametric approach. The results showed that using the complete model, wind shear, turbulence, and absence of fragment rotation caused the fragments to impact within shorter distances; fragment rotation and lack of wind decreased the probability of impact within a given distance, but the rupture probability of the target was not affected by fragment rotation or wind. The probabilistic confidence intervals of fragment range, impact, and target penetration became narrower with the number of simulation runs, but the accuracy of the results increased. The probability of fragment impact increased with the volume of the target vessel and the degree of filling of the explosion vessel, but did not depend on the kind of explosion. The probability of target rupture increased slowly with the degree of filling of the explosion vessel, but was little influenced by the volume of the target vessel or the kind of explosion.

Cost‐Benefit Analysis of Passive Fire Protections in Road LPG Transportation

The cost-benefit evaluation of passive fire protection adoption in the road transport of liquefied petroleum gas (LPG) was investigated. In a previous study, mathematical simulations of real scale fire scenarios proved the effectiveness of passive fire protections in preventing the "fired" boiling liquid expanding vapor explosion (BLEVE), thus providing a significant risk reduction. In the present study the economical aspects of the adoption of fire protections are analyzed and an approach to cost-benefit analysis (CBA) is proposed. The CBA model is based on the comparison of the risk reduction due to fire protections (expressed in monetary terms by the value of a statistical life) and the cost of the application of fire protections to a fleet of tankers. Different types of fire protections were considered, as well as the possibility to apply protections to the entire fleet or only to a part of it. The application of the proposed model to a real-life case study is presented and discussed. Results demonstrate that the adoption of passive fire protections on road tankers, though not compulsory in Europe, can be economically feasible, thus representing a concrete measure to achieve control of the "major hazard accidents" cited by the European legislation.

Calculating the explosion energy of a boiling liquid expanding vapor explosion using exergy analysis

AbstractFollowing 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. 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 based on the rigorous and unambiguous definition for exergy. © 2011 American Institute of Chemical Engineers Process Saf Prog, 2012

Analysis of Accidental Consequence of Butadiene Tank

Butadiene is a kind of important material in the chemical engineering, and it is inflammable and explosive. Once it leaks to the air, fire and explosion accident may happen. In the current experiment, the Butadiene tank in a chemical plant was taken as the example to analyze the potential hazards that the tank may cause. Some mathematical models, such as the UVCE（the Unconfined Vapor Cloud Explosion） and the BLEVE（the Boiling Liquid Expanding Vapor Explosion）, were used to describe the results that the hazards may lead to，so that it could provide some scientific criteria to the similar companies, and help the companies to take measures to keep away from these dangers, and reduce the casualty and loss in the end.

Class-2 hazmat transportation consequence assessment on surrounding population

The transportation of hazardous materials by road is an utmost necessity of the world for the societal benefits, but at the same time the activity is inherently dangerous. Incidents involving hazardous material (hazmat) cargo particularly the class-2 materials can lead to severe consequences in terms of fatalities, injuries, evacuation, property damage and environmental degradation. The rationale behind considering class-2 hazmats is that they pose the greatest danger to the people and property along the transport route because of their storage condition on the transport vessel. They are stored either in pressurized vessels or in cryogenic containers. Any external impact due to collision may cause catastrophic failure of transport vessels, known as BLEVE (Boiling Liquid Expanding Vapour Explosion) with devastating consequences. Further, any continuous release from containment may cause what is known as ‘Unconfined Vapour Cloud Explosion’ (UVCE). Historically frequency of BLEVE occurrence is of the order of 1 × 10 −6 per year or less, but other release scenarios e.g. a large vapour or liquid leaks are more probable and could also have devastating effects on the surrounding population. As such, the paper discussed various event scenarios and the consequences taking examples of a class-2.1 material (1,3 butadiene) and another class-2.3 (ammonia) hazmat. Comparative analysis suggests that per ton basis a rupture of ammonia tanker gives rise to larger impact areas and poses larger lethality risks compared to 1,3 butadiene as far as toxic effects are concerned. Besides, from fireball fatality on similar basis propylene causes higher consequence distance than LPG followed by ethylene oxide and 1,3 butadiene. The impact zone study results may be utilized as inputs for identifying the potential vulnerable area on a GIS enabled map, along a designated State highway route passing through an important industrial corridor in western India.

Route risk evaluation on class-2 hazmat transportation

Incidents involving hazardous material (hazmat) road tankers carrying class-2 materials may pose the greatest danger to the people and property along the transport route because of their storage condition on the transport vessel i.e. stored either in pressurized vessels or in cryogenic containers and lead to severe consequences in terms of fatalities, injuries, evacuation, property damage and environmental degradation. The worst case of release may result into phenomenon like Boiling Liquid Expanding Vapor Explosion (BLEVE) due to collision related catastrophic failure of vessel and an Unconfined Vapor Cloud Explosion (UVCE) due to delayed ignition following a large release. The impact zones or vulnerable areas have been identified along two designated. State highway routes passing through an important industrial corridor in Western India and mapped on a GIS enabled local map. HAMS-GPS software was used for the analysis of flammables and ALOHA for toxic hazmat consequences. The route risks are compared which have been estimated based on the population likely to be affected within the lethality impact areas created by the worst case release scenarios of different class-2 hazmats, namely LPG, ethylene oxide, propylene, 1,3-Butadiene, ammonia and chlorine, enabling proper routing decision by local authorities and also for planning emergency mitigating actions.

Study on Quantitative Risk Assessment of LGP Transportation in Road Tunnel

Based on the tunnel environment and the characteristic of flammability and explosion of liquefied petroleum gas (LGP), the leak of LPG tanker can induce heavy casualties and property loss in the tunnel. In order to study quantitative risk of LGP transportation in road tunnel, the data of 599 accidents and 659 accidental vehicles are collected. From these data, the proportion of LGP tanker accident in the total accident vehicles and million vehicles kilometer (MVK) tanker accident rates are obtained. By analyzing the leakage scene of LGP tanker, the possible accident types of the LGP transportation were analyzed, such as boiling liquid expanding vapor explosion (BLEVE), vapor cloud explosion (VCE), flash fire and jet fire, etc. The impact of leak time to various ranges of injury is studied in the condition of LGP continued leakage. The slight injury, serious injury and death radius of LGP leakage accidents are calculated in tanker loaded with different LGP quantity. In view of the accidental analysis, the countermeasures will be proposed to reduce the risk of LGP transportation in road tunnel.

Comparative consequence analysis of the BLEVE phenomena in the context on Land Use Planning; Case study: The Feyzin accident

Several technological accidents have occurred in the oil/gas refining and petrochemical industries, involving large quantities of LPG (Liquefied petroleum Gas), all having in common BLEVE (Boiling Liquid Expanding Vapor Explosion) phenomena. The new Member States of the European Union have to adopt the Seveso Directives, but after 3 years of membership there is still a gap in the Romanian legislation regarding a specific methodology for the calculation of Land Use Planning (LUP) distances in case of Seveso-type industrial sites. These distances were calculated for a BLEVE event, considering the French, Italian and Austrian LUP methodologies. The results were compared to establish which methodology is more adequate for the development of Romanian LUP methodology. The paper also presents an innovative approach of BLEVE modeling with the purpose to compare the measured consequences of the Feyzin (France) accident with the simulation results obtained using three available BLEVE models: static, dynamic and rupture of vessel. The investigations and simulation results demonstrate the theory that in case of BLEVE the thermal effects of the fireball are more severe than the effects of the blast wave, therefore, the recommended approach is to calculate the heat load from the fireball, using the French LUP threshold limits.

Experimental studies on the thermal stratification and its influence on BLEVEs

Abstract The thermal stratification of Liquefied Petroleum Gas (LPG) and its effect on the occurrence of the boiling liquid expanding vapor explosion (BLEVE) have been investigated experimentally. Stratifications in liquid and vapor occur when the LPG tank is heated. The degree of the liquid stratification β increases with an increasing heat flux and decreasing filling ratio. The effect of stratification on the BLEVE has been examined with depressurization tests of LPG. The results show that the pressure recovery for the stratified LPG (β = 1.4) upon sudden depressurization is much lower than that for the isothermal LPG (β = 1). It can be concluded that the liquid stratification decreases the liquid energy and the occurrence of the BLEVE.

Boiling Liquid Expanding Vapor Explosion: Simulation and Risk Analysis

A model was developed for estimating the thermodynamic and the dynamic state of the boiling liquid during a boiling liquid expanding vapor explosion (BLEVE) event. The model predicts, simultaneously, the bubble growth processes in the liquid at the superheat-limit state, the front velocity of the expanding two-phase mixture, and the shock wave pressure formed by the fluid expansion through the air. The model predictions of the shock wave strengths, in terms of TNT equivalence, were compared against those obtained by simple energy models. The study reveals what are the important mechanisms that dominate two-phase blowdown and BLEVE accidents. The research presents an overview of the mechanism, the causes, the consequences, and the preventive strategies associated with BLEVEs. They are therefore important computational tools for environmental safety assessments.

An Energy Fluctuation Approach to Calculate Homogeneous Nucleation Rate in Superheated Liquids and Its Verification by Performing an LPG Rapid Discharge Experiment

To investigate conditions that are likely to produce a boiling-liquid-expanding-vapor explosion (BLEVE), the determination of homogeneous nucleation rates of superheated liquids is often crucial. A new approach to estimate nucleation rates of superheated liquids is proposed; the approach is based on the probability distribution of the energy fluctuation within the framework of statistical thermodynamic fluctuation theory. Formulae for calculating the homogeneous nucleation rate in Gibbs canonical ensembles are deduced and tested for some substances. The calculated rates are compared with those obtained by the commonly used kinetic method as well as with experimental values. Finally, the new approach is validated by analyzing pressure rebounds of rapid discharge of pressurized liquefied petroleum gas (LPG). From the pressure rebound conditions, estimates of homogeneous nucleation rates can be obtained with both the kinetic and energy fluctuation approaches. Comparison of calculated results reveals that the new energy fluctuation approach is reasonably effective and has practical relevance in BLEVE research.

Risk reduction in road and rail LPG transportation by passive fire protection

The potential reduction of risk in LPG (Liquefied Petroleum Gas) road transport due to the adoption of passive fire protections was investigated. Experimental data available for small scale vessels fully engulfed by a fire were extended to real scale road and rail tankers through a finite elements model. The results of mathematical simulations of real scale fire engulfment scenarios that may follow accidents involving LPG tankers proved the effectiveness of the thermal protections in preventing the “fired” BLEVE (Boiling Liquid Expanding Vapour Explosion) scenario. The presence of a thermal coating greatly increases the “time to failure”, providing a time lapse that in the European experience may be considered sufficient to allow the start of effective mitigation actions by fire brigades. The results obtained were used to calculate the expected reduction of individual and societal risk due to LPG transportation in real case scenarios. The analysis confirmed that the introduction of passive fire protections turns out in a significant reduction of risk, up to an order of magnitude in the case of individual risk and of about 50% if the expectation value is considered. Thus, the adoption of passive fire protections, not compulsory in European regulations, may be an effective technical measure for risk reduction, and may contribute to achieve the control of “major accidents hazards” cited by the European legislation.

The Quantitative Assessment of Domino Effects Based on Stochastic Petri Nets

The quantitative analysis of “domino” effects is one of the main aspects of hazard assessment in chemical industrial park. This paper demonstrates the application of heterogeneous stochastic Petri net modeling techniques to the quantitative assessment of the probabilities of domino effects of major accidents in chemical industrial park. First, five events are included in the domino effect models of major accidents: pool fire, explosion, boiling liquid expanding vapour explosion (BLEVE) giving rise to a fragment, jet fire and delayed explosion of a vapour cloud. Then, the domino effect models are converted into Generalized Stochastic Petri net (GSPN) in which the probability of the domino effect is calculated automatically. The Stochastic Petri nets’ models, which are state-space based ones, increase the modeling flexibility but create the state-space explosion problems. Finally, in order to alleviate the state-space explosion problems of GSPN models, this paper employs Stochastic Wellformed Net (SWN), a particular class of High-Level (colored) SPN. To conduct a case study on a chemical industrial park, the probability of domino effects of major accidents is calculated by using the GSPN model and SWN model in this paper.

The boiling liquid expanding vapour explosion (BLEVE) is fifty … and lives on!

The boiling liquid expanding vapour explosion (BLEVE) is among the most fearsome of accidents that can occur wherever a pressure liquefied gas (PLG) exists. If a container with a PLG suffers structural failure—be it due to creep, fatigue, or fire-induced or other forms of accidental jeopardy—it may lead to a sudden depressurization of the container. As a result, the PLG will suddenly be transformed into a liquid which is ‘superheated’ in respect of the precipitously lowered pressure. Depending on the nature of the chemical, its quantity, and the mechanism of the container failure, such a situation can lead to instantaneous and violent vaporization of the contents, causing a ‘boiling liquid expanding vapour explosion’—a BLEVE. Even though BLEVEs have been occurring ever since the use of pressure liquified gases began, they were not recognized or studied as a clearly distinct form of explosion that they are, until 1957. In that year, three engineers working in USA coined the term BLEVE when they witnessed an explosion which could not be categorized by any of the explosion types known till then. Even though, as described in this paper, the acronym took time to gain wide currency, it has served the very important purpose of giving the BLEVE phenomenon a distinct identity. This, in turn, has stimulated considerable work towards the understanding and control of BLEVEs. In this commemorative piece, which marks the 50th year of the coinage of the BLEVE acronym, we recall the event which led to the coinage, and the pioneering work of the three who introduced BLEVE to the world—J.B. Smith, W.S. Marsh, and W.L. Walls.

Boiling liquid expanding vapor explosion: Experimental research in the evolution of the two-phase flow and over-pressure

In a boiling liquid expanding vapor explosion (BLEVE), the superheating and boiling of the liquefied gas inside the vessel as it fails is important information necessary to understand the mechanism of this type of disaster. In this paper, a small-scale experiment was developed to investigate the possible processes that could lead to a BLEVE. Water was used as the test fluid. High-speed video was utilized to observe the two-phase flow swelling which occurred immediately following the partial loss of containment through a simulated crack. The velocity of the two-phase swelling was measured along with pressure and temperature. It was observed that initially a mist-like two-phase layer was rapidly formed on the liquid surface (∼3–4 ms) after the vessel opened. The superheated liquid rapidly boiled and this accelerated upwards the two-phase layer, the whole liquid boiled after about 17 ms form opening. It was supposed that the swelling of the two-phase layer was the possible reason for the first over-pressure measured at the top and bottom of the vessel. From 38 ms to 168 ms, the boiling of the superheated liquid weakened. And from 170 ms, the original drop/mist-like two-phase flow turned into a churn-turbulent bubbly two-phase flow, rose quickly in the field of the camera and eventually impacted the vessel top wall. The force of its impact and “cavitation” and “choke” following with the two-phase ejection were maybe main reasons for the second obvious pressure increasing.

Evaluation of the blast-wave overpressure and fragments initial velocity for a BLEVE event via empirical correlations derived by a simplified model of released energy

When a pressure vessel filled with a liquid is involved in a fire, a variety of effects are to be expected. If the vessel is filled with LPG, a boiling liquid expanding vapour explosion (BLEVE) is one of the possible effects, although it does not always happen. Actually BLEVE is a complex phenomenon resulting from many factors which are hard to summarize into mathematical formulations or models. Nevertheless it could be useful in order to assess the consequences of a BLEVE, to have access to simplified models lying on physical basis. In this paper empirical correlations for blast-wave overpressure and fragments initial velocity are presented. The basic hypothesis that BLEVE is a phenomenon driven by the excess heat stored in the liquid (overheated liquid) is assumed and some thermodynamic approximations are introduced. Despite these approximations and the empirical formulation simplicity, the results accuracy is good.

An overview on BLEVE

PurposeThis paper aims to provide graduate students, researchers and government and independent agencies with an overview on BLEVE (i.e. boiling liquid expanding vapour explosion).Design/methodology/approachBLEVE has been studied by researchers, academicians, company specialists, and government and independent agencies. BLEVE incidents are collected from several sources such as technical and general articles, internet web sites and internal reports. BLEVE definitions, history, theory, types, hazards, and models are reviewed. BLEVE incidents are arranged and classified into fires, overfilling, explosions, overheating, runaways, overpressure, collisions, corrosion, and damage (derailment).FindingsBLEVE types are classified into cold BLEVEs, hot BLEVEs, and BLEVEs. The major consequences of a BLEVE are thermal radiation from the resultant fireball and the fragments produced when the vessel fails. Several approaches are developed to describe BLEVE theory. BLEVE incidents are classified into explosions, damage (derailment), overfilling, fires, collisions, runaways, overpressure, overheating, and corrosion. The world has witnessed 74 BLEVE incidents in the period 1926‐1986. BLEVE incidents resulted in 1,427 fatalities and 635 injuries. The materials involved in BLEVE were flammable and non‐flammable. The highest frequencies of BLEVE incidents were due to explosions and damage to tanks. Explosion and damage BLEVE incidents resulted in high injuries. Overfilling and fire BLEVE incidents resulted in high fatalities.Originality/valueThis paper presents an overview of BLEVE definitions, history, incidents, types, theory, hazards and models. BLEVE incidents are classified. This paper combines scattered BLEVE incidents into one record.

1D plane numerical model for boiling liquid expanding vapor explosion (BLEVE)

The depressurization of a vessel containing saturated or subcooled liquid may occur in a variety of industrial processes and often poses a potentially hazardous situation. A 1D plane numerical model was developed for estimating the thermodynamic and the dynamic state of the boiling liquid during a boiling liquid expanding vapor explosion (BLEVE) event. Based on the choice of the initial nucleation sites density, the model predicts, simultaneously, the bubble growth processes in the liquid at the superheat-limit state, the front velocity of the expanding liquid, and the shock wave pressure formed by the liquid expansion through the air. Conditions of shock formation were found to be normally associated with high initial temperatures that can bring the liquid to its superheat-limit state during the initial depressurization. Furthermore, the high initial temperature also induces a generation of higher vapor pressures that forces a rapid mixture expansion. Model predictions of the shock wave strengths, in terms of TNT equivalence, were compared against those obtained by simple energy models. As expected, the simple energy models over predicts the shock wave strength. However, the simple model which accounts for the expansion irreversibility, produces results which are closer to current model predictions.

Blast overpressures from medium scale BLEVE tests

The measured blast overpressures from recent tests involving boiling liquid expanding vapour explosions (BLEVE) has been studied. The blast data came from tests where 0.4 and 2 m 3 ASME code propane tanks were exposed to torch and pool fires. In total almost 60 tanks were tested, and of these nearly 20 resulted in catastrophic failures and BLEVEs. Both single and two-step BLEVEs were observed in these tests. This paper presents an analysis of the blast overpressures created by these BLEVEs. In addition, the blast overpressures from a recent full scale fire test of a rail tank car is included in the analysis. The results suggest that the liquid energy content did not contribute to the shock overpressures in the near or far field. The liquid flashing and expansion does produce a local overpressure by dynamic pressure effects but it does not appear to produce a shock wave. The shock overpressures could be estimated from the vapour energy alone for all the tests considered. This was true for liquid temperatures at failure that were below, at and above the atmospheric superheat limit for propane. Data suggests that the two step type BLEVE produces the strongest overpressure. The authors give their ideas for this observation. The results shown here add some limited evidence to support previous researchers claims that the liquid flashing process is too slow to generate a shock. It suggests that liquid temperatures at or above the Tsl do not change this. The expansion of the flashing liquid contributes to other hazards such as projectiles, and close in dynamic pressure effects. Of course BLEVE releases in enclosed spaces such as tunnels or buildings have different hazards.