Explosion, exothermic reactions

Nitroanatine Piant Explosion Exothermic Reactions That Hun Away... 

EXPLOSION and FIRE CONCERNS nonflammable NFPA rating (NA) reacts violently or explosively upon heating when mixed with aluminum powder will ignite at high temperatures when mixed with phosphorus mixtures with diazomethane vapor can result in an explosive exothermic reaction when primed at a high temperature with a potassium nitrate-calcium silicide mixture, mixtures with excess red phosphorus will bum containers may explode when heated toxic fumes of oxides of sulfur are emitted when heated to decomposition use water spray, dry chemical, carbon dioxide, fog, or regular foam for firefighting purposes. 

Precaution Potentially explosive exothermic reaction with chlorine... 

Energy Chemical oxidizer disassociation, organic compounds and explosives Fire, explosion, exothermic reaction, production of toxic fumes, corrosion/corrosive fumes, etc. 

If the gaseous products are heated, an explosive exothermic reaction takes place. 

The exothermic reaction can be explosive. Therefore, it is preferable to initiate the reaction by using an alkyl haUde at a lower temperature at which the reaction rate is controlled by the haUde concentration. 

Hydrochloric acid may conveniently be prepared by combustion of hydrogen with chlorine. In a typical process dry hydrogen chloride is passed into a vapour blender to be mixed with an equimolar proportion of dry acetylene. The presence of chlorine may cause an explosion and thus a device is used to detect any sudden rise in temperature. In such circumstances the hydrogen chloride is automatically diverted to the atmosphere. The mixture of gases is then led to a multi-tubular reactor, each tube of which is packed with a mercuric chloride catalyst on an activated carbon support. The reaction is initiated by heat but once it has started cooling has to be applied to control the highly exothermic reaction at about 90-100°C. In addition to the main reaction the side reactions shown in Figure 12.6 may occur. 

Polymerization Exothermic reaction which, unless carefully controlled, can run-away and create a thermal explosion or vessel overpressurization Refer to Table 7.20 for common monomers Certain processes require polymerization of feedstock at high pressure, with associated hazards Many vinyl monomers (e.g. vinyl chloride, acrylonitrile) pose a chronic toxicity hazard Refer to Table 7.19 for basic precautions... 

The kinetics and thermodynamics of the reaction, and of possible side reactions, need to be understood. The explosive potential of chemicals liable to exothermic reaction should be carefully appraised. 

Chemical Reactivity - Reactivity with Water Reacts vigorously as an exothermic reaction. Forms beryllium oxide and hydrochloric acid solution Reactivity with Common Materials Corrodes most metals in the presence of moisture. Flammable and explosive hydrogen gas may collect in confined spaces Stability During Transport Stable Neutralizing Agents for Acids and Caustics Flush with water and rinse with dilute solution of sodium bicarbonate or soda ash Polymerization Not pertinent Inhibitor of Polymerization Not pertinent. 

In a batch reaction plant, an exothermic reaction was cooled by water circulating in a jacket. The circulating pump failed and the reactor went out of control causing a violent explosion. A low flow alarm was present but was inoperable. A critical pump bearing had not been lubricated during maintenance, and the collapse of the bearing had led to the pump failure. 

A deflagration is a slow burning exothermic reaction similar to the combustion explosion, but which propagates from the burning gases into the unreacted material at a velocity that is less than the speed of sound in the unreacted material. Most (not all) explosions are deflagrations. 

Detonation explosions are similar to combustion explosions and are exothermic reactions that proceed into the unreacted material at a velocity much greater than the speed of sound in an unreacted material and are accompanied by a flame front shock wave in the material followed closely by a combustion wave that releases the energy and sustains the shock wave at extremely high pressure [39] [40]. In hydrocarbons, the velocity can reach 6,000-9,000 ft/sec. 

In 1969 a serious explosion took place in Basle when 287 kg (1.3 kmol) of 2-chloro-4,6-dinitroaniline was diazotized in 384 kg 40% nitrosylsulfuric acid. The temperature was increased from 30 °C to 50 °C and kept at that level. Shortly afterwards the explosion occurred three workers were killed and 31 injured, some seriously. The reaction had been carried out twice before in the same way without difficulty. Detailed investigations (Bersier et al., 1971) with the help of differential scanning calorimetry showed that, at the high concentration of that batch, a strongly exothermic reaction (1500 kJ/kg) starts at about 77 °C. In contrast, when the reactants were diluted with 96% sulfuric acid to twice the volume, the reaction was found to begin at 146 °C, generating only 200 kJ/kg. 

Exothermic reaction which, unless carefully controlled, can run-away and create a thermal explosion or vessel overpressurization... 

Common reaction rate v. temperature characteristics for reactions are illustrated in Figure 6.5. To avoid runaway conditions (Fig. 6.5a) or an explosion (Figure 6.5c), it may be essential to control the rate of addition of reactants and the temperature. The kinetics and thermodynamics of the reaction, and of possible side reactions, need to be understood. The explosive potential of chemicals liable to exothermic reaction should be carefully appraised. 

The heat accelerates the exothermic reaction, which produces even more heat. The process goes on until all of the explosive has been consumed. Explosions can also occur on surfaces. 

When considering the thermal management of very exothermic reactions and the avoidance of corresponding explosions, it is the minute volume of micro readors that is addressed [4]. 

Reduction and exothermic reactions, hazard associated with use of hydrogen (high hydrogenation flammability, explosion possible)... 

Its oxidising character plays a role in all other reactions. Surprisingly, it is thought to form explosive dichlorine oxide with chlorine. It leads to a and very exothermic reaction with disulphur dichloride and detonations with metals potassium, K-Na alloy, magnesium with phosphorus and anhydrous or hydrated hydrazine. 

Twenty tons of ethylene oxide were contaminated by ammonia accidentally. The tank broke open releasing a fume cloud , which gives rise to a devastating explosion. Again, it is rather difficult to interpret this accident. Indeed, it could be a violent polymerisation, which was the result of the catalytic effect of ammonia or a very exothermic reaction ... 

Potential explosion phenomena include vapor cloud explosions (VCEs), confined explosions, condensed-phase explosions, exothermic chemical reactions, boiling liquid expanding vapor explosions (BLEVEs), and pressure-volume (PV) ruptures. Potential fire phenomena include flash fires, pool fires, jet fires, and fireballs. Guidelines for evaluating the characteristics of VCEs, BLEVEs, and flash fires are provided in another CCPS publication (Ref. 5). The basic principles from Reference 5 for evaluating characteristics of these phenomena are briefly summarized in this appendix. In addition, the basic principles for evaluating characteristics of the other explosion and fire phenomena listed above are briefly summarized, and references for detailed evaluation of characteristics are provided. 

As a vessel of a given shape increases in size, both the surface area and the volume increase, but they do not increase at the same rate. For a sphere the surface area is a function of the diameter squared and the volume is a function of the diameter cubed. This is also true for a cylinder whose height is a multiple of its diameter. The polymerization of styrene is an exothermic reaction. The amount of energy released at any time is dependent on the volume of the reactor, and the rate of removal of that heat is dependent on the surface area. Unless the heat is removed, the temperature will rise and the reaction rate will increase. The result will be an uncontrolled reaction that not only may ruin the batch but could also damage the reactor and might cause a tire or explosion to occur. 

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