Burning zone

The capacity of a sintering strand is related direcdy to the rate at which the burning zone moves downward through the bed (78). This rate is... 

Special purpose and blended Portland cements are manufactured essentially by the same processes as ordinary Portland cements but have specific compositional and process differences. White cements are made from raw materials of very low iron content. This type is often difficult to bum because almost the entire Hquid phase must be furnished by calcium aluminates. As a consequence of the generally lower total Hquid-phase content, high burning-zone temperatures may be necessary. Past cooling and occasionally oil sprays are needed to maintain both quaHty and color. 

The produrtive capacity of a sintering strand is related directly to the rate at which the burning zone moves downward through the bed. This rate, which is of the order of 2.5 cm/min (1 in/min), is controlled by the air rate through the bed, with the air functioning as the heat-transfer medium. 

These characteristics influence furnace plan area, furnace volume, and burning zone size reqmred to maintain steam production capacity for a given fuel grade or quahty. 

When a vapor cloud bums, there is always a leading flame front propagating with uniform velocity into the unbumed cloud. The leading flame front is followed by a burning zone. 

When gas concentrations are high, burning is characterized by the presence of a tall, turbulent-diffusion, flame plume. At points where the cloud s vapor had already mixed sufficiently with air, the vertical depth of the visible burning zone is about equal to the initial, visible depth of the cloud. 

Regeneration was carried out as the catalyst fell through various burning zones. The flue gases were recycled by being directed to the turbo-compressors that the pressurized air used as fuel m the combustion process. 

Korotkov et al (Ref 67) also stress the importance of convective burning in DDT. They claim that the length of the run-up zone to detonation is determined by dp/dt in the burning zone. The value of dp/dt in turn is determined by the specific burning surface and the permeability, pore size and compressibility of the expl... 

Electron-density effects on fi-decay lifetimes also enable the total density to be placed in the range 2500 to 13 000 gm cm-3 all these parameters are characteristic of helium shell-burning zones as expected. 

Explosion is a term that corresponds to rapid heat release (or pressure rise). An explosive gas or gas mixture is one that will permit rapid energy release, as compared to most steady, low-temperature reactions. Certain gas mixtures (fuel and oxidizer) will not propagate a burning zone or combustion wave. These gas mixtures are said to be outside the flammability limits of the explosive gas. 

FIGURE 9.21 Sample oxygen profiles through the char particle boundary layer and the char particle itself during combustion proceeding according to the characteristic burning zones. 

Figure 4 Details of the burning zone. (A) Side of trolley, (B) Mesh...

The volume of air drawn through the burning zone during the appHcation of a pressure difference to the butt end of the cigarette wiU have a substantial effect on the mainstream smoke yield. TTie laboratory smoking machine is required to take standard puffs for each cigarette. 

The plot of air flow-rate as a function of time is called the puff profile. Variations in this wiU change the temperature profile within the burning zone and thus affect smoke yields. The laboratory smoking machine must reproducibly generate a heU-shaped puff profile to accepted standards. 

The results of Fig. 19.8 for a swirl number of 1.35 show that the attenuation increased to 10 dB with the velocity of the axial jet up to 42 m/s, and further increase to 47 m/s caused the amplitude to fall from around 6 kPa to less than 1.5 kPa and the attenuation to decrease from 10 dB to almost zero. Similar results were observed with the swirl number of 0.6 the attenuation improved with axial jet velocity up to 60 m/s, after which the amplitude and attenuation decreased. The decline in the amplitude of oscillation and its attenuation by active control was due to the interaction between the axial jet with a large velocity and the central recirculation zone, which caused the flame to move further downstream of the swirler and heat release to occur further from the pressure antinode. The consequent increase in the distance between the point of entry of the oscillated fuel and the active burning zone reduced the effectiveness of the oscillated input due to increased fluid dynamic damping and development of a large difference in phase between different parts of the oscillated flow, especially with swirl surrounding the oscillated axial jet. 

Fig. 13.16 Stable, oscillatory, and unstable burning zones for a lead-catalyzed double-base propellant.

Concealed burning zones within coal scams ... 

Emitted from burning zones within spoil heap... 

Localized risks to human health from hums (c.g.. victims fall into burning zone) and/or asphyxiation by smoke (especially where fumes enter conlined spaces) (Straeher et al. 2002) [Sec also entry ahovc under Air pollution combustion fumes from burning spoil )... 

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