Explosion fundamentals

An explosion pressure, Pex, is tlie pressure in excess of tlie initial pressure at wliich tlie explosive nii, ture is ignited. Tlie rate of pressure rise is represented by clP/dt, a pressure cliange witli respect to time. Tliis is a measure of tlie speed of 

TABLE 7.4.3 Influence of tlie Type of Ignition Source and of tlie Ignition Energy on tlie Explosion Data of Combustible Dusts (1-m  

Type of Dust Ignition Sourde Ignition Energy (J) P max (bar) Ka (bar-m/s) 

The maximum explosion pressure is a function of the initial pressure, P. If Ore initial pressure is increased by a factor of 2, die maxiinum explosion pressure and the maxunum pressure rise will also increase by a factor of about 2 for both flammable gas and dust mixtures. Wlien tlie initial pressure is less than 10 mbar, it is usually no longer possible to liave an explosion. 

Another mediod of estimating die effects of explosions in process plants is represented by 

An explosion is defined by StrelUow and Baker as an event in wliich energy is released over a sufficiently small period of time and in a sufficiently small volmne to generate a pressure wave of finite amplitude traveling away from tlie source. Tliis energy may have been originally stored in tlie system as chemical, nuclear, electrical, or pressure energy. However, tlie release is not considered to be explosive unless it is rapid and concentrated enough to produce a pressure wave tliat can be heard. 

Explosions, Toxic Emissions, and Hazardous Spills 

TABLE 7.4.2 Ksi Values of Teclmical Fine Dusts High Ignition Energy  

Energy on tlie Explosion Data of Combustible Dusts (1-m  

D = chemical detonator, C = condenser discliarge, S = permanent spark gap. 

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Theofanous, T.G., W.W. Yuen, S. Angelini, X. Chen, W.H. Amarasooriya and S. Medhekar (1993) Steam Explosions Fundamentals and Energetic Behavior, to be published as a NUREG/CR report. 

This chapter concludes our discussion of applications of surface chemistry with the possible exception of some of the materials on heterogeneous catalysis in Chapter XVIII. The subjects touched on here are a continuation of Chapter IV on surface films on liquid substrates. There has been an explosion of research in this subject area, and, again, we are limited to providing just an overview of the more fundamental topics. 

The next part of the procedure involves risk assessment. This includes a deterrnination of the accident probabiUty and the consequence of the accident and is done for each of the scenarios identified in the previous step. The probabiUty is deterrnined using a number of statistical models generally used to represent failures. The consequence is deterrnined using mostiy fundamentally based models, called source models, to describe how material is ejected from process equipment. These source models are coupled with a suitable dispersion model and/or an explosion model to estimate the area affected and predict the damage. The consequence is thus determined. 

Most modem projectiles and virtually all missiles contain explosives. The plasmas that result from explosives are intrinsic to operation of warheads, bombs, mines, and related devices. Nuclear weapons and plasmas are intimately related. Plasmas are an inevitable result of the detonation of fission and fusion devices and are fundamental to the operation of fusion devices. Compressed pellets, in which a thermonuclear reaction occurs, would be useful militarily for simulation of the effects of nuclear weapons on materials and devices. 

Safety issues are not covered here. These are dealt with in Systems and Equipment book, and some fundamental issues will be taken up in the second edition of the Fundamentals book. The following aspects should be taken into account in system design fan safety AHU fire protection issues safety measures in mines, tunnels, underground car parks, etc. transportation of chemical and explosives. 

Optical devices or optical systems have provided most of the available strong shock data and were the primary tools used in the early shock-compression investigations. They are still the most widely used systems in fundamental studies of high explosives. The earliest systems, the flash gap and mirror systems on samples, provided discrete or continuous measurements of displacement versus time. 

In relatively low-reactive fuel-air mixtures, a detonation may only arise as a consequence of the presence of appropriate boundary conditions to the combustion process. These boundary conditions induce a turbulent structure in the flow ahead of the flame front. This turbulent structure is a basic element in the feedback coupling in the process by which combustion rate can grow more or less exponentially with time. This fundamental mechanism of a gas explosion has been described in Section 3.2. 

The combustion-flow interactions should be central in the computation of combustion-generated flow fields. This interaction is fundamentally multidimensional, and can only be computed by the most sophisticated numerical methods. A simpler approach is only possible if the concept of a gas explosion is drastically simplified. The consequence is that the fundamental mechanism of blast generation, the combustion-flow interaction, cannot be modeled with the simplified approach. In this case flame propagation must be formalized as a heat-addition zone that propagates at some prescribed speed. 

In the preceding sections, combustion was modeled as a prescribed addition of energy at a given speed. The fundamental mechanism of a gas explosion, namely, feedback in combustion-flow interaction, was not utilized. As a consequence, the behavior of a freely propagating, premixed, combustion process, which is primarily determined by its boundary conditions, was unresolved. 

Several methods of quantiflcation are described in Chapter 4. Chapter 4 discusses in detail two fundamental approaches to quantiflcation of explosive power, together with advantages and disadvantages. In addition, there are two different blast models, each of which has certain benefits. This chapter offers guidance on their use. Application of each method is described in Section 7.2. and demonstrated in Section 7.3. Section 7.1. offers some guidance on choosing an approach and a blast model. 

In cases where information about atomic arrangements cannot be obtained by X-ray crystallography owing to the insolubility or instability of a compound, vibrational spectroscopy may provide valuable insights. For example, the explosive and insoluble black solid SesNaCla was shown to contain the five-membered cyclic cation [SesNaCl]" by comparing the calculated fundamental vibrations with the experimental IR spectrum. ... 

Some of tlie preceding cliapters liave dealt witli tlie history and legislation of emergency and accidents tliis cliapter addresses specifically tlie fundamentals of plant fires, explosions, and certain otlier plant- and non-plant-related accidents. 

D. R. Stuwl, Fundamentals of Fires and Explosions, Vol. 73, American Institute of Chemical Enginccrs-Dow Chemical Company, Midland Ml, 1977. 

This book is divided into five parts the problem, accidents, health risk, hazard risk, and hazard risk analysis. Part 1, an introduction to HS AM, presents legal considerations, emergency planning, and emergency response. This Part basically ser es as an oveiwiew to the more teclmical topics covered in the remainder of the book. Part 11 treats the broad subject of accidents, discussing fires, explosions and other accidents. The chapters in Parts 111 and Part IV provide introductory material to health and hazard risk assessment, respectively. Pai1 V examines hazaid risk analysis in significant detail. The thiee chapters in this final part include material on fundamentals of applicable statistics theory, and the applications and calculations of risk analysis for real systems. 

Nitric acid is one of the three major acids of the modem chemical industiy and has been known as a corrosive solvent for metals since alchemical times in the thirteenth centuiy. " " It is now invariably made by the catalytic oxidation of ammonia under conditions which promote the formation of NO rather than the thermodynamically more favoured products N2 or N2O (p. 423). The NO is then further oxidized to NO2 and the gases absorbed in water to yield a concentrated aqueous solution of the acid. The vast scale of production requires the optimization of all the reaction conditions and present-day operations are based on the intricate interaction of fundamental thermodynamics, modem catalyst technology, advanced reactor design, and chemical engineering aspects of process control (see Panel). Production in the USA alone now exceeds 7 million tonnes annually, of which the greater part is used to produce nitrates for fertilizers, explosives and other purposes (see Panel). 

Stull, D. R., Fundamentals of Fire Explosion, Monograph Series, No. 10, Vol 73, The Dow Chemical Co., published Amer. Inst. Chem. Engrs., 1977. 

Study of Fundamental Properties of High Explosives , PATR 861 (1937) 8) D.R. Beeman,... 

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