1,102 research outputs found
An Experimental Study of Water BLEVE
No full textInternational audienceA boiling liquid expanding vapor explosion (BLEVE) is an explosion caused by a sudden rupture of a vessel containing a pressurized liquid at a temperature above its boiling point. A BLEVE can occur with all types of liquids and is not a particular phenomenon for flammable liquefied gases such as propane or butane. A particular hazard in the hydrocarbon industry is the use of water at temperatures far above their atmospheric boiling point in steam generation systems. Water is present at high pressure (e.g. 7 MPa) and high temperature (e.g. 300°C). At these conditions the water is superheated and in case of an accidental release the water will undergo a rapid vaporization and a BLEVE type explosion can be expected. This hazard is quit wide spread in all refineries, petrochemical plants, etc. but little data can be found in literature about real size water BLEVE experiments. The aim of this work was to perform BLEVE tests thanks to a 14L pressure vessel designed on purpose to produce high pressure water BLEVE (85 bar). An extended set of pressure gauges was set in the vessel to measure the internal phase change pressure dynamics and around the relief rupture disk to capture the blast wave. Temperature of water was also recorded, and a fast camera (Phantom V2512) was used to see the phenomenon. Data show clearly the pressure recovery in the vessel and multiple blast waves around the vessel. Results are discussed to analyse the risk of water BLEVE
An experimental study of water BLEVE
No full textInternational audienceA boiling liquid expanding vapour explosion (BLEVE) is a physical explosion caused by a sudden rupture of a vessel containing superheated liquid. A BLEVE can occur with many types of fluids and is not an exclusive phenomenon for flammable liquefied gases such as propane or butane. Other superheated liquids suffering a fast depressurization at high temperature may entail a BLEVE, such as water in steam generation systems. Several pieces in literature suggest that superheated water may produce a BLEVE, but little experimental data can be found on that topic.The aim of this work was to perform water BLEVE tests with a 14 L pressure vessel designed on purpose to produce high superheated liquid water (290 °C; 75 bar) and to trigger a BLEVE through calibrated rupture disks. Pressure sensors were set in the vessel to measure the internal phase change pressure dynamics and other aerial overpressure sensors were put around the relief rupture disk to capture the blast wave. Temperature of water was also recorded, and a fast camera (Phantom V2512) was used to see the phenomenon.Data show clearly the pressure recovery due to rapid boiling in the vessel. Explosive boiling did not add additional internal pressure force on the containment. Two main blast waves were observed, they were strongly related with outlet orifice area but little dependant on filling ratio. The two phase jet reached a 20 m range
Thermodynamic and gas dynamic aspects of a BLEVE
No full textThis first chapter will give an introduction to what is a BLEVE, Boiling Liquid Expanding Vapor Explosion, and its hazards particularly in relation to tunnel safety. It will be shown that several definitions of a BLEVE can be given, depending on the aspect put in focus. In particular distinction can be made between two groups of references, respectively giving an engineering definition and a physical definition. As a result of our literature survey, our own definition of BLEVE will be presented trying to bridge the gap between these two groups of definitions. In the following chapters, we stick to that definition unless specified otherwise. First of all, we would like to consider some basic concepts, i.e. superheated liquid, explosive boiling and bubble nucleations, by an easy example. It is well known that when we heat the water in a tea kettle up to the temperature of 100 ±C at the atmospheric pressure, the water will start to boil or vaporize. In this case, invisible active nuclei formed on the inner surface of the kettle or at any impurities in the water will grow to be a visible bubble which will detach from the wall and move upwards due to buoyancy. Such a type of bubble nucleation is called heterogeneous nucleation since the bubble nucleation only occurs at the locations where there is a boundary between two different phases. However if we put the water into a very smooth glass and heat it in the microoven, the boiling will not occur even the temperature already exceeds the normal boiling point at the atmospheric pressure. At this moment, the water is said to be superheated and if we keep heating the water, a rapid ’explosive-like’ boiling, termed explosive boiling, will suddenly occur and may cause serious damage to the microoven. In this explosive boiling, the active nuclei are evenly formed throughout the liquid, therefore it is called homogeneous nucleation. Superheating sometimes is referred to as boiling retardation, or boiling delay. It refers to the phenomenon in which a liquid is heated to a temperature higher than its boiling point, without actually boiling. A superheated state can also be reached in another way than by heating, namely by depressurization to a pressure lower than the saturation pressure at the prevailing temperature
Structure-function studies of a Pleurotus eryngii laccase isoform by a protein engineering approach.
No full textLaccases are biotechnological relevant enzymes belonging to the group of polyphenol oxidases. Three-dimensional crystal structures analyses of fungal laccases showed that ascomycete laccases are processed at their C-termini at a conserved cleavage site, resulting in the proteolytic removal of C-terminal residues. We have isolated and cloned the cDNAs encoding the Ery3 and Ery4 laccases from Pleurotus eryngii. The Ery3 gene was functionally expressed in Saccharomyces cerevisiae, whereas the recombinant Ery4 protein did not show enzymatic activity. In order to explain this evidence, we investigated the relationship between the structure of the carboxyl-terminal extension and the enzymatic laccase activity. The tasks of the present study were to determine the biological role of laccase C-terminal and to validate a “protein engineering” approach for the production of recombinant laccases with novel biochemical properties. We produced several mutant genes derived from the ERY4 by: i) progressive 3’-terminal deletions, ii) point mutations, iii) ERY3/ERY4 chimeras. The obtained genes were expressed in S. cerevisiae and several recombinant active laccase isoforms were produced, each showing different biological behaviors. The correlations between the structural information deriving from the biochemical and bioinformatic analyses shed light on the role of laccase C-terminal region in determining laccase functions. The obtained data also indicated that the employed approach could represent an efficient method for laccase protein engineering. To our knowledge, this study has produced the first evidences of the involvement of the C-terminal tail in the inactivation/activation mechanism of a basidiomycete laccas
Mechanism and destruction status of CO2 BLEVE during CO2 geological storage and enhanced oil recovery injection process
No full textIn CO2-oil recovery enhancement technology, the occurrence of a Boiling Liquid Expansion Vapor Explosion (BLEVE) can result in dangerous events that endanger the lives and health of workers, while also leading to significant economic losses. This happens when there is an excessive injection concentration and volume of CO2, coupled with container defects. To address the limited research on the mechanism and destruction of BLEVE, this study conducts experiments to explore these issues. The experimental results reveal that the bursting piece ruptures at a temperature of 36 °C, and the specimen explodes when the pressure intensity exceeds the residual strength of the specimen, reaching 69.97 MPa. The findings indicate that parameters, such as initial pressure, initial temperature, and failure pressure, can impact the risk of CO2 BLEVE occurrence and the propagation of explosion shock waves. The pressure inside the container during the BLEVE process fluctuates due to the joint action of the leakage rate and gasification rate of liquid CO2. This research provides a framework for evaluating the risk of CO2 BLEVE during CO2 geological storage and enhanced oil recovery injection processes, offering theoretical support for BLEVE prevention and control
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