Explosive region

Fig. 35. Explosive limits of CI2—H2—other gas mixtures where M represents the explosive region in the presence of residue gas from CI2 Hquefaction (O2,...

Fig. 6. Approximate explosive limits of styrene monomer vapor in equiUbrium with Hquid styrene in air, where represents the explosive region. To...

Multiple fluid streams in medium- to large-scale processes become important for many oxidation reactions. MicroChannel operation allows safe operation in the explosive regions [42, 43], but this advantage ceases as the dimensions become... 

Emulsions formed from immiscible organic liquids in aqueous peroxide mixtures may behave in the same way as miscible organic liquids, but if the emulsion breaks and separation of the organic phase occurs, passage into an explosive region of the peroxide-water-organic liquid ternary system may occur, and this is potentially very dangerous. 

Division designations are categorized in relationship to the probability of the material being within the flammable or explosive regions ... 

The gases in the ethylene oxide reactor moved into the explosive region while being above the autoignition temperature. A violent explosion occurred, resulting in several injuries and significant plant damage. 

Thus, another reason to stay out of the vapor phase explosion region is to prevent the ignition of a liquid phase explosion. 

At the third limit, above 3000 Torr, the mixture again enters an explosive region. At these high pressures, diffusion of H02 to the wall is so slow that this species has sufficient time to react in the gas phase. Thereby a new chain-propagating reaction pathway opens up, initiated by... 

Data are not available about the rate of reaction in the non-explosive region. 

What will happen is that flames and black smoke will pour out of the heater s stack. It looks very bad, very dangerous, but it is really not. There is not enough excess oxygen in the firebox to cause a very high temperature. The combustion gases, or flue gas, are too fuel-rich to explode. We say that the flue gas is above the explosive region. 

To prevent the flue gas from exploding, we need to proceed rather cautiously. If we just block in the leaking process tubes and fuel-gas supply, the fuel gas content of the flue gas will gradually decrease. The air fuel ratio in the flue gas will increase until the flue-gas composition enters the explosive region. If the firebox refractory walls are still hot enough to initiate combustion, the firebox will now explode. 

The correct way to prevent this sort of firebox explosion is to use firebox purge steam. A typical heater firebox might have a half dozen 3-in purge steam connections. The idea is to displace the air in the firebox with steam. Then, the flows of combustible process liquid and fuel gas may be safely stopped, without fear of entering the explosive region. This purge steam is different from the purge steam used in the heater s tubes. 

The non-explosive region where reaction is in the steady state ... 

The reaction between hydrogen and oxygen is a branched chain reaction which shows explosive regions. It has been very extensively studied, and appears to have a very complex mechanism. 

The third pressure limit, when it exists, occurs at even higher pressures. At the third limit, i.e. at pressures greater than at d, the reaction moves back into an explosive region which is in part thermal, and in part the result of some dramatic change in radical concentration. This results from another set of reactions coming into play so that gas phase termination can no longer cope with this new production of radicals. 

Oxidation of hydrocarbons - mechanism and steady state analysis, 229-232 A stylised branched chain mechanism - a steady state analysis, and kinetic criteria for the explosive region, 246-249... 

Step 1. For this process we must be able to set the production rate of vinyl acetate while minimizing yield losses to carbon dioxide. During the lifetime of the catalyst charge, catalyst activity decreases and the control system must operate under these different conditions. To maintain safe operating conditions, the oxygen concentration in the gas loop must remain outside the explosivity region for ethylene. The azeotropic distillation column must produce an overhead product with essentially no acetic acid and a bottoms product with no vinyl acetate. The absorber must recover essentially all of the vinyl acetate, water, and acetic acid from the gas recycle loop to prevent yield losses in the CCf removal system and purge,... 

Fio. XTV.4. Explosion limits of a stoichiometric mixture of IE + O2 in a KCl-coatcd spherical vessel (7.4 c.in diameter). Explosive region lies in shaded region to right of (jritical boundary first limit is somewhat erratic . Dashed parts of curve represent extrapolations. 

The cool flame phenomenon seems to be closely tied to the formation of aldehydes and peroxides in oxidation systems. In Fig. XIV. 10 is shown a typical example of the explosion limits for a hydrocarbon-oxygen mixture. The explosion region, except for a region of positive slope, resembles the limit curve for a thermal explosion. The transition between slow combustion and explosion is characterized by an intense luminous blue flame which appears after a short induction period and is followed by explosion. The induction periods are not more than a few seconds. 

Of greater interest is the occurrence of the explosion region at low pressures [9—12] where, just outside the explosion limit, the rate of... 

There have been a number of measurements of the effects of mixture composition and temperature on the hydrogen—oxygen second limits in potassium chloride coated vessels (e.g. refs. 28,14, 23, 25, 30). Typical of the results are the explosion regions shown in Figs. 3 and 4. They all... 

Clearly the rate of the chain terminating process will increase more rapidly with pressure than the rate of chain branching, so that an upper limit to the explosion region will occur. Equating the two rates at the limit... 

Development of the reaction with time within the explosion region... 

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