Combustion, atmospheric

Pj = the maximum initial pressure at which the combustible atmosphere exists, psig R = the ratio of the maximum deflagration pressure to the maximum initial pressure, as described in Code Par 5-3.3.1... 

Pd = ASME Code design pressure (or maximum allowable working pressure), psi Pdo = pressure on outlet side of rupture disk, psia Pe = exit or back pressure, psia, stamped burst pressure Per = perimeter of a cross section, ft or meters Pn = Initial high pressure, mmHg Pj = maximum initial pressure at which the combustible atmosphere exists, psig P j = initial pressure of system, psia PL = initial low pressure or vacuum, mmHg Pmax =- maximum explosion pressure, bar, or other consistent pressure units... 

DOT. 1994b. Simultaneous gas-chromatographic determination of four toxic gases generally present in combustion atmospheres. Report to U.S. Department of Transportation, Federal Aviation Administration, Office of Aviation Medicine by the Civil Aeromedical Institute, Oklahoma City, OK. 

Investigation of Combustion Atmospheres in Real Fires. U.S.F.A. Project 80027, Southwest Research Institute, 1981. 

The principle of oxygen consumption is an empirical finding that the rate of heat release is proportional to the decrease in oxygen concentration in the combustion atmosphere [20, 21]. Thus, cone calorimeter heat release measurements do not require adiabaticity of reactions. Therefore, the combustion process can be carried out more openly, and reactions seen with the naked eye. The Cone calorimeter contains a load cell and can, thus, measure any property on a per mass lost basis. This permits... 

During the evaluation it is assumed that ignition of an existing combustible atmosphere is always possible. The assessment is thus independent of the question of whether ignition sources are present. 

I-3.6.2 Electronic control, monitoring, and hydrogen gas measurement equipment shall be properly grounded and isolated from piping to help prevent overpressure/ accidental shutoff situations caused by equipment failure due to lightning strikes and electrical transients and to prevent safety hazards caused by fault currents. Electrical isolation equipment for corrosion control purposes should not be installed in buildings unless specifically designed to be used in combustible atmospheres. 

Ash related problems such as agglomeration occur, and exchange of the sand bed may be needed after some interval (Bridgwater, 2003). One way to overcome some problems with agglomeration is to use a mixture of biomass and peat in order to increase the melting point of the raw material in the furnace. It is also possible to use lime (contains CaO, Ca, etc.) instead of quartz in the fluidised bed reactor to improve the agglomeration temperature in the combustion atmosphere of some biomass (Natarajan et al., 1998). 

D.A. Purser and W.D. Woolley, Biological studies of combustion atmospheres, Journal Fire Science, 1, 118-144, 1983. 

These methods are now indispensable for mechanistic analysis of many practical chemical systems involving highly complex reactions, including oxidation, combustion, atmospheric chemistry and pyrolysis. With recent extensions of thermochemical kinetics estimation methods to coal-related molecules (2, 3,4 and free radicals (5), it is now feasible to apply thermochemical kinetics analysis to a wide range of coal-related chemical systems. Thermochemical and kinetics estimation methods are particularly suited for analysis of coal systems since these methods are applicable not only to reactions of molecules but also to reactions of specific molecular structures. 

Some years ago, Directive 94/9/EC (the so-called ATEX 100a Directive ), dated 1994-03-23 (following the title in French Atmospheres explosibles. .. and referring to article 100a of the Treaties of the European Community), introduced categories of explosion protected apparatus to give a guideline for their installation with respect to the risks that may be expected in different locations exposed to combustible atmospheres (Table 2.3). 

All the facts given above refer to normal operation. How can a p-apparatus start to operate Due to duty cycles and the thermal cycles caused thereby, a non-operating electrical apparatus located in a hazardous area shall be considered as filled with combustible atmosphere (an example is calculated in Section 6.7.1). 

There are no inherent degradation mechanisms to limit the life of thermionic converters. The lifetime of test devices has usually been related to damage from the environment of the heat source. Converters with nuclear fuel are affected by fisson product swelling, which distorts the emitter. Flame heated converter lifetimes are controlled by the durability of the hot shell, which protects the emitter from the combustion atmosphere. 

Therefore, and because of the Ca presence, a possible Ca catal)4ic role could be guessed. The chelating mechanisms reported [10,11] at polymeric pyrolysis can not be applied to coal combustion because the inert-reducing atmosphere at pyrolysis process has not relation to the oxidation conditions at the combustion atmospheres. However, other additional effect in the LCL runs could influence the PAH emission and distribution. This effect would be a possible catalytic role performed by Ca. 

Chain reactions are recursive reaction cycles that regenerate their intermediates. Such cycles occur in combustion, atmospheric chemistry, pyrolysis. photolysis, polymerization, nuclear fusion and fission, and catalysis. Typical steps in these systems include initiation, propagation, and termination. often accompanied by chain branching and various side reactions. Examples 2.2 to 2.5 describe simple chain reaction schemes. 

The 30 min LC50 of O2 is 5.4%, a value that is included in the model by subtracting the combustion atmospheric O2 concentration from the normal concentration of O2 in air, that is, 21%. The LC50 values of HCl or HBr for 30 min exposures plus postexposures times are 3700 and 3000 ppm, respectively. 

These improvements in pull capacity are due to the improved heat flux density to the glass, which results in a faster melt rate. In addition, the ability of an oxy/fuel furnace to distribute heat input to the most ideal locations within the furnace helps to improve pull capacity. Some claim that the water content in the glass increases because of the different combustion atmosphere for oxy/fuel.1 More water or hydroxyl ions in the glass decrease the viscosity of the melt allowing improved circulation of the melt. 

Free radicals, or radicals, are defined as atomic or molecular species with unpaired electrons on an otherwise open shell configuration. Because a radical has a half-filled orbital, it easily sucks up an electron from another bond, hence exhibiting highly reactive properties and therefore likely to take part in chemical reactions. The first organic free radical is the triphenylmethyl radical, which was identified by Moses Gomberg in 1900 [34], Radicals play an important role in chemical processes such as combustion, atmospheric chemistry, polymerisation, plasma chemistry, biochemistry, etc. [35],... 

The ratio of anthropogenic emissions to total natural emissions is highest for the atmophilic elements Sn, Cu, Cd, Zn, As, Se, Mo, Hg, and Pb (Lantzy and Mackenzie, 1979). In the case of lead, atmospheric concentrations are primarily the consequence of leaded gasoline combustion. Atmospheric fluxes of lead in the USA rose steadily from... 

Stage 2, Calcination Zone When the magnesite reaches a temperature of about 750°C, the pressure of carbon dioxide produced by dissociation of magnesite equals the partial pressure of CO2 in the combustion atmosphere. As the magnesite progresses through the calcination zone, the temperature further rises and the surface layer of the ore begins to decompose. 

There has been relatively little work published on the reaction of titanium aluminides in atmospheres other than air or oxygen. Niu et al. [96] studied the reaction of Ti-25Al-llNb in a simulated combustion atmosphere (N2+1%02+ 0.5%SO2) with and without surface deposits of Na2S04-t- NaCl at temperatures between 600 and 800°C. Exposures in the absence of surface deposits resulted in reaction rates similar to those described above for simple oxidation. The rates in the presence of the deposits at 600 and 700 °C were initially rapid and then slowed markedly after 25 to 50 hours exposure. The rate at 800°C remained rapid with the kinetics being essentially linear. The major difference in the corrosion morphology at 800 °C was the presence of copious amounts of sulfides below the oxide scales. The authors postulate a mechanism of attack involving a combination of sulfidation-oxidation and scale-fluxing. 

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