Explosion physical

A physical explosion relates to the catastrophic rupture of a pressurized gas filled vessel. Rupture could occur for the following reasons  

Failure of pressure regulating and pressure relief equipment (physical overpressurization) 

Any other incident which results in loss of process containment. 

Failure can occur at or near the operating pressure of the vessel (items 2 and 3 above), or at elevated pressure (items 1 and 4 above). 

When the contents of the vessel are released both a shock wave and projectiles result. The effects are more similar to a detonation than a vapor cloud explosion (VCE). The extent of a shock wave depends on die phase of the vessel contents originally present. Table 3.6 describes the various scenarios. 

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It is convenient to calculate a TNT equivalent of a physical explosion to use the military results of Figures 9.1-4 and 5. Baker et al. (1983) give a recipe for the rupture of a gas filled container assuming expansion occurs isothermally and the perfect gas laws apply (equation 9.1-25), where W is... 

A rapid loss of containment of a pressurized gas or vapor (not necessarily flammable material), called a PV rupture (a type of physical explosion), may produce fragment effects as well as a blast wave as the rapidly expanding fluid compresses the surrounding air. If the material released is flammable, a PV rupture may also be followed by a fireball. 

Another type of physical explosion can occur upon rapid vaporization of a liquid when contacted with a significantly hotter material (e.g., water added to vessel containing hot oil). This is also referred to as a rapid phase transition explosion. In addition to blast, physical explosions can also generate fragments when initially confined. 

Identify the inventories of flammable and combustible materials within the process plant and the physical conditions under which they are contained. Similarly, identify other materials or process conditions that can result in explosion events, including condensed-phase explosions, physical explosions, or uncontrolled chemical reactions. 

Physical explosion Any explosion where the energy release is due to a physical, as opposed to a chemical, process. 

I Spontaneous reaction Static electricity Physical explosions... 

BLEVEs/Pressure-volume Ruptures/Physical Explosions. Rapid loss of containment of materials confined under pressure at temperatures above their normal boiling point may result in a BLEVE, with blast, radiant heat (if flammable material is involved), as well as fragment effects. These effects can be experienced for considerable distances, depending upon the types and volumes of material stored. 

Catastrophic rupture of a pressure vessel as a result of a PV rupture or physical explosion may also result in blast and fragment effects. 

Vessel mptures can also occur when a higher-temperature liquid or solid is combined with a cooler low boiling liquid, transferring sufficient heat from the hotter material to the colder material such that the colder material rapidly vaporizes. No chemical reactions are involved instead, the explosion occurs because the cooler liquid expands as it is converted to vapor, creating high pressures. These are called physical explosions. A common example is a steam explosion, which occurs when liquid water is accidentally introduced into a process vessel operating at an elevated temperature. If the hotter material is above the superheat limit temperature of the evaporating liquid, initial confinement by a vessel is not required to create an explosion pressure wave. 

Liquid ammonia and the solvent may explode when mixed. (It is possible this was a liquefied gas (physical) explosion, rather than an exothermic chemical reaction.)... 

A physical explosion, for example, a boiler explosion, a pressure vessel failure, or a BLEVE (Boiling Liquid Expanding Vapor Explosion), is not necessarily caused by a chemical reaction. Chemical explosions are characterized as detonations, deflagrations, and thermal explosions. In the case of a detonation or deflagration (e.g., explosive burning), a reaction front is present that proceeds through the material. A detonation proceeds by a shock wave with a velocity exceeding the speed of sound in the unreacted material. A... 

Henry, R. E., and Fauske, H. K. (1976). Nucleation characteristics in physical explosions. Spec. Meet. Sodium Fuel Interact. Fast React., 3rd, 1976, Tokyo, Japan. 

Nelson, H. W. (1971). Preventing physical explosion due to the interaction of liquid water and molten chemical compounds. U.S. Patent 3,615,175. 

Nelson, H. W. (1973). A new theory to explain physical explosions. Tappi 56(3), 123. Nelson, H. W. (1978). Method of preventing explosions using a smelt water explosion inhibitor. U.S. Patent 4,106,978. 

Application of physical explosions, while important, are less so than those of the chemical types, described below... 

These types of explosion can be divided into three groups physical explosions such as the over-pressurized steam boiler, chemical explosions as in the chemical reactions of explosive compositions, and atomic explosions. 

A physical explosion can arise when a substance whilst being compressed undergoes a rapid physical transformation. At the same time, the potential energy of the substance is rapidly transformed into kinetic energy, and its temperature rises rapidly, resulting in the production of a shockwave in the surrounding medium. 

An example of a physical explosion is the eruption of the Krakatoa volcano in 1883. During this eruption a large quantity of molten lava spilled into the ocean causing about 1 cubic mile of sea water to vapourize. This rapid vaporization created a blast wave which could by heard up to 3000 miles away. 

Physical explosions are those in which no chemical or nuclear reaction occurs. The most frequent example is the rupture of a vessel whose contents, either gas or liquid, exist under high pressure. If the containing vessel bursts, its contents are free to expand and a shock wave is formed. Even a common automobile tire can explode if it is highly overinflated. 

The operations team in this area of the plant was convinced that if changes were to be made in any equipment, reactants, intermediates, catalyst, or any operating conditions of the process were modified, the system would be first reviewed by a committee. In the operations teams mind, this was just a waste water line. As is apparent in Figure 2—18, the danger of just blocking the water drain lines at any time the system is in operation would cause physical explosion. 

A physical explosion usually results from the production of large volumes of gases by nonchemical means. The gases necessary for a physical explosion may be those already existing, such as compressed nitrogen released suddenly from a ruptured cylinder, or steam released explosively from a crack in a steam drum. 

The following are some settings and situations in which physical explosions have been known to take place ... 

A physical explosion process which, like the Armstrong process and Airdox process, operates on the principle of a sudden release of compressed gas by means of a bursting disc. In the Cardox process, condensed C02 is brought to a high vapor pressure by means of a... 

This means "Boiling Liquid Expanding Vapor Explosion" and characterizes the physical explosion of a liquefied gas/supercritical fluid that is brutally decompressed to atmospheric pressure, in case of pressure vessel rupture or opening. Catastrophic BLEVE occurred when liquefied petroleum gases vessels burst (Mexico, Feyzin,...), followed by the "chemical" explosion due to gas cloud inflammation. In fact, this hazard is directly linked to metal weakening in case of fire around the vessel(s). It is the reason why it is recommended to install fire detectors that could order immediate depressurization of the whole plant in case of fire. 

The most serious accident tlial cnuclear plant is a reactor core meltdown. In a core meltdown, the enclosed gases physically melt through tlie reactor vessel, and once contacting with cooler liquids or apors either in a cooling jacket or in the outer em iromnent, cause a physical explosion to occur, However, tlie haztird caused by the explosion itself is minimal and more localized compared with the release of radioactive niaterial that accomptmies such an accident. 

The term explosion is best defined as a process that involves a sudden release of energy resulting in a rapid and significant buildup of overpressure. Explosions can be categorized into physical/mechanical and chemical explosions. For example, an explosion caused by a sudden release of compressed gas is a physical explosion. A chemical explosion is caused by a chemical reaction(s), which could be combustion, exothermic decomposition or exothermic reaction. Chemical explosions can occur in gas, liquid or solid phase. Chemical explosions that occur in liquid and solid phases are sometimes called condensed phase explosions. Explosive explosions fall in this category. 

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