Explosions heat of explosion

Designation Content of Water in Charge, % Density of Charge, g/cm3 Heat of Explosion, cal/g, explosive Heat of Explosion, cal/g, mixture... 

Addition of hydrazine, urea perchlorate, hydrazine nitrate, or hydrogen peroxide (H2O2) into the formula of liquid explosives significantly increases the explosion heat. Besides above chemicals, adding the powders of aluminum, magnesium, or beryllium also raises the explosion heat of explosives. Increasing the explosion heat improves the work capacity of explosives. 

Explosion heat of explosive can be determined experimentally, and can also be calculated with theoretical methods in the design of its formula. During the calculation of explosion heat with theoretical method, chemical composition, explosive reaction equations, and required thermochemical data of the designed explosive must be known first, then the empirical approach Hess law can be used for the calculation. 

Fig. 3.3 Hess triangle diagram of explosion heat of explosives...

According to Eq. 3.5, explosion ways of explosive, and formation heat values of explosives and explosion products, the explosion heat of explosive can be calculated. Based on the explosion reaction, explosion equations close to the real reactions could be figured out, the formation heat of explosives and explosion products can be found in the relevant manuals, and formation heat values of some substance and explosive were listed in Table 3.4. If the formation heat of explosive is not known, it can be obtained through the combustion heat experiment or the associated calculation methods. 

For example, the calculation of explosion heat of explosive Amatol 80/20 is the following. Its explosion reaction equation is,... 

However, the impact of shell was not very significant on the explosion heat of explosives with low negative oxygen balance, positive oxygen balance, and zero oxygen balance. 

Table 3.7 Influence of water content on explosion heat of explosive...

Explosion heat of explosive is an important indicator to measure its explosion properties, and the improvement of explosion heat means the improvement of its explosion energy. According to the design calculations of explosion heat, it could be improved through these following methods. 

The calculation of explosion heat of explosive involves its formation heat, therefore, its explosion heat not only depends on element composition of the explosive,... 

When any substituent is introduced in hydrocarbon molecules to saturate double bond or triple bond, the electronic structure of molecule will be changed, thus the thermal effect of electron transfer of 1 mol atom will have some change. According to the impact of change in molecule structure, the explosion heat of explosive can be calculated based on the corresponding corrected thermochemical data of some groups and the corrected data are listed in Table 3.9. The combustion heat of CaHi,OcN compounds under constant pressure can be calculated as the following equation ... 

Energetic plasticizers are defined as the liquid materials having a positive heat of explosion. Heat of explosion is the energy released by burning the propellant or ingredient in an inert atmosphere and then cooling to ambient temperatures in a fixed volume. 

The problem of explosion of a vapor cloud is not only that it is potentially very destructive but also that it may occur some distance from the point of vapor release and may thus threaten a considerable area. If the explosion occurs in an unconfined vapor cloud, the energy in the blast wave is generally only a small fraction of the energy theoretically available from the combustion of all the material that constitutes the cloud. The ratio of the actual energy released to that theoretically available from the heat of combustion is referred to as the explosion efficiency. Explosion efficiencies are typically in the range of 1 to 10 percent. A value of 3 percent is often assumed. 

Example 9.1 A process involves the use of benzene as a liquid under pressure. The temperature can be varied over a range. Compare the fire and explosion hazards of operating with a liquid process inventory of 1000 kmol at 100 and 150°C based on the theoretical combustion energy resulting from catastrophic failure of the equipment. The normal boiling point of benzene is 80°C, the latent heat of vaporization is 31,000 kJ kmol the specific heat capacity is 150 kJkmoh °C , and the heat of combustion is 3.2 x 10 kJkmok. ... 

A similar analysis for fluorination of methane gives AH° = -426 kJ for its heat of reaction Fluori nation of methane is about four times as exothermic as chlorination A reaction this exothermic if it also occurs at a rapid rate can proceed with explosive violence... 

Explosive Detonation pressure, GPa Bulk specific gravity Detonation velocity, km/s Contains high explosives Heat of detonation kj /g Excavated vol relative to equal wt of TNT... 

Many nitrated products are explosives, including DNT, TNT, and nitroglycerine (NG). At least some mononitroaromati.es can also be exploded under certain conditions (20). Because of the high heats of nitration, mnaway reactions followed by severe explosions have occurred in industrial batch nitrators. To rniiiimi2e these potential ha2ards, the compositions of the feed acids and reaction conditions are currently better controlled than formerly. 

Ha/ogenation. Heats of reaction are highly exothermic for halogens, particularly fluorine (qv), and chain reactions can result in explosions over broad concentration ranges. Halogens also present severely challenging corrosion problems (see Corrosion and corrosion control). 

Hydrides. Zirconium hydride [7704-99-6] in powder form was produced by the reduction of zirconium oxide with calcium hydride in a bomb reactor. However, the workup was hazardous and many fires and explosions occurred when the calcium oxide was dissolved with hydrochloric acid to recover the hydride powder. With the ready availabiHty of zirconium metal via the KroU process, zirconium hydride can be obtained by exothermic absorption of hydrogen by pure zirconium, usually highly porous sponge. The heat of formation is 167.4 J / mol (40 kcal/mol) hydrogen absorbed. 

Dichlorine monoxide is the anhydride of hypochlorous acid the two nonpolar compounds are readily interconvertible in the gas or aqueous phases via the equilibrium CI2 O + H2 0 2H0Cl. Like other chlorine oxides, CI2O has an endothermic heat of formation and is thus thermodynamically unstable with respect to decomposition into chlorine and oxygen. Dichlorine monoxide typifies the chlorine oxides as a highly reactive and explosive compound with strong oxidhing properties. Nevertheless, it can be handled safely with proper precautions. 

Many finely divided metal powders in suspension in air are potential e] losion hazards, and causes for ignition of such dust clouds are numerous [Hartmann and Greenwald, Min. MetalL, 26, 331 (1945)]. Concentration of the dust in air and its particle size are important fac tors that determine explosibility. Below a lower Umit of concentration, no explosion can result because the heat of combustion is insufficient to propagate it. Above a maximum limiting concentration, an explosion cannot be produced because insufficient oxygen is available. The finer the particles, the more easily is ignition accomplished and the more rapid is the rate of combustion. This is illustrated in Fig. 20-7. 

Explosions in the Absence of Air Some gases with positive heats of formation can be decomposed explosively in the absence of air. Ethylene reacts explosively at elevatea pressure and acetylene at atmospheric pressure in large-diameter piping. Heats of formation of these materials are -t-52.3 and -t-227 kj/mol (-1-22.5 and -1-97.6 X 10 Btii/lb mol), respec tively. 

A common cause of a BLE T] in plants of the hydrocarbon-chemical industry is exposure to fire. With an external fire below the liquid level in a vessel, the heat of vaporization provides a heat sink, as with a teakettle evolved vapors exit tnrough the relief valve. But if the flame impinges on the vessel above the liquid level, the metal will weaken and may cause the vessel to rupture suddenly, even with the relief valve open. The explosive energy for a BLE T] comes from superheat. This energy is at a maximum at the superheat hmit temperature. (SLT is the maximum temperature to which a hquid can be heated before homogeneous nucleation occurs with explosive vaporization of the hquid and accompanying overpressure.) The SLT... 

In a 2-1. round-bottomed, 3-necked flask fitted with a stirrer and two large-bore condensers are placed 200 cc. of 50 per cent nitric acid and 0.25 g. of vanadium pentoxide. The flask is heated to 65-70° in a water bath (thermometer in water), and I cc. of cyclopentanone added. Oxidation is indicated by the production of brown fumes. The water bath is removed, and 42 g. (less the i cc.) of the cyclic ketone added from a dropping funnel through the condenser at the rate of a drop every three seconds. The heat of the reaction keeps the flask at about 70°. If the temperature drops, oxidation ceases until the ketone has accumulated, when it may proceed almost explosively. In such a case, or if the temperature is higher, much succinic acid is formed. After addition has been completed, the water bath... 

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