Combustion from explosives

Dust Filter. The cloth or bag dust filter is the oldest and often the most reHable of the many methods for removing dusts from an air stream. Among their advantages are high (often 99+%) collection efficiency, moderate pressure drop and power consumption, recovery of the dust in a dry and often reusable form, and no water to saturate the exhaust gases as when a wet scmbber is used. There are also numerous disadvantages maintenance for bag replacement can be expensive as well as a sometimes unpleasant task these filters are suitable only for low to moderate temperature use they cannot be used where Hquid condensation may occur they may be hazardous with combustible and explosive dusts and they are bulky, requiring considerable installation space. 

Turbulence may arise by two mechanisms. First, it may result either from a violent release of fuel from under high pressure in a jet or from explosive dispersion from a ruptured vessel. The maximum overpressures observed experimentally in jet combustion and explosively dispersed clouds have been relatively low (lower than 1(X) mbar). Second, turbulence can be generated by the gas flow caused by the combustion process itself an interacting with the boundary conditions. 

As a general mle, WT boilers are safer from explosion than FT boilers because the dmm is not exposed to the radiant heat of combustion. If tubes rupture, there is only a relatively small volume of water that can instantly flash to steam. 

In a somewhat different type of furnace that suffered from a combustion-gas explosion, the floor beams, which were similar in size, were deflected at most 2-3 cm. A structural analysis of this explosion led to the conclusion that peak pressures were in the order of 30-40 kN/m (5-6 psi). Comparing the two damage descriptions, it is obvious that the smelt-water explosion generated pressures well in excess of 40 kN/m on the floor. 

Title of Journal which is a translation from Russian. It is published by The Faraday Press, Inc, NY, 10011. In Vol 1, pp 3-4 (Jan-March 1965) there is an article by M.A. Lavrent ev, entitled Future Developments in the Field of Combustion and Explosion . 

Combustion to Explosion, Transition. See under Detonation (or Explosion), Development (or Transition) from Combustion (or Burning) or from Deflagration... 

The solution of the Poisson-Boltzmann equation with. the application to thermal explosions) 5) D.A. Frank-Kamenetskii, "Diffusion and Heat Exchange in Chemical Kinetics, pp 202-66, Princeton Uni v-Press, Princeton, NJ (1955) (Quoted from MaSek s paper) 6) L.N. Khitrin, "Fizika Goreniya i Yzryva (Physics of Combustion and Explosion), IzdMGU, Moscow (1957)... 

It is obvious that with an insufficient chemical reaction rate we should expect deviations from this picture. By analogy with other combustion and explosion phenomena we may expect that a decrease in the chemical reaction rate with all other conditions equal first only causes some quantitative change—widening of the reaction zone, and then, after some critical value has been reached, the flame will be extinguished, combustion will become impossible and will stop and in its stead mixing of the cold gas and air without any reaction will occur. Below we shall attempt to analyze the critical conditions of quenching in the simplest, schematic case. 

During maintenance work, simultaneous release of chlorine and acetylene from two plants into a common vent line leading to a flare caused an explosion in the line [10]. The violent interaction of liquid chlorine injected into ethane at 80°C/10 bar becomes very violent if ethylene is also present [11]. The relationship between critical pressure and composition for self-ignition of chlorine—propane mixtures at 300°C was studied, and the tendency is minimal for 60 40 mixtures. Combustion is explosive under some conditions [12]. Precautions to prevent explosions during chlorination of solid paraffin hydrocarbons are detailed [13]. In the continuous chlorination of polyisobutene at below 100°C in absence of air, changes in conditions (increase in chlorine flow, decrease in polymer feed) leading to over-chlorination caused an exotherm to 130°C and ignition [14],... 

Generally speaking, combustion is a heat-releasing chemical oxidation reaction, which is often accompanied by the occurrence of a flame. Flame temperatures differ widely from approx. 2000 K for an open flame to approx. 3000 K for the flame of an acetylene cutting torch. Remarkably, the heats of combustion of explosives is generally lower than those of common fuels (pine wood with 12.9% water 4.422 kcal/g, acetylene 11.923 kcal/g, dynamite 75% 1.290 kcal/g. 

From the literature analyses we see that organic fillers have thermal expansion coefficients (TEC) values close to those of thermoplasts [7], they have low abrasiveness, their density is similar to that of thermoplasts [6, 8] but as a rule, their grindig is difficult [9], they are combustible and explosive, not thermostable and not always cheap [9]. Mineral fillers are comparatively easy to grind, their cost is low, they are thermostable and non-combustible, but their TEC s are an order lower than those of thermoplasts. As a rule, their density 2-3 times higher than the thermoplasts [6]. Their abrasiveness is too high. 

Because of the large amount of heat release from combustion, gas explosions always involve high temperature rise. For example, the maximum flame temperatures for hydrogen and methane are 2045°C and 1875°C, respectively.f l Even for weak deflagrations in fuel-lean mixtures near the LFL, the flame temperatures of hydrocarbons are in the range of 1300-1350°C (p. 330 in Ref9 (). This is why even weak deflagrations such as flash fires can cause severe burn injuries. 

Zeldovich, Y.B. Barenblatt, G.I. Librovich, V.B. Makhviladze, G.M. The Mathematical Theory of Combustion and Explosions translated from Russian by McNeill, D.H. Consultants Bureau New York, 1985. 

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