Burning interruption

The condensed-phase reaction zone of a burning-interrupted BAMO copolymer is identified by infrared (IR) spectral analysis. In the non-heated zone, the absorption of the N3 bond, along with the absorptions of the C-O, C-H, and N-H bonds. 

Fig. 13.18 Combustion instability of a six-pointed-star grain, showing DC and AC components of pressure and the cross-section of the grain (1) before ignition and (2) after burning interruption.

This is very common nowadays to allow bargaining on fuel price or to arrange an interruptible gas tariff, which is backed up at times of peak demand with a stored oil supply. Most types of oil and gas burner are available in dual-fuel form, normally with gas burner design wrapped around the arrangement for oil firing. This is usually the more difficult fuel to burn, particularly in the case of residual heavy oils. Fuel selection is normally by a switch on the burner control panel after isolation has taken place of the non-fired fuel. To avoid the cost and complexity of the fuel preheating on oil firing, smaller systems use gas oil as the standby fuel. 

Due to interruptible gas tariffs, it is often necessary to adopt gas as the primary fuel and burn oil in periods of peak loads. This means that the economizer has to be arranged so that when oil firing, the flue gases are bypassed around the economizer. The bypass duct must also contain a damper to simulate the economizer gas resistance so that the burner back pressure remains the same for both fuels. Figure 25.6 shows a typical installation layout. 

Fast burn-out, Fig. 4A, occurs when the temperature rise is very rapid, for example, less than one second elapsing between the initiation of burn-out and the time at which the metal temperature becomes dangerously high. Unless the channel power is quickly interrupted, a fast burn-out will usually result in physical burn-out. Lee and Obertelli (L4) report having examined a large number of instrument traces to see whether fast burn-out could be associated with any particular ranges of flow velocity, pressure, or quality at the burn-out point, but no generalization could be made. However, it does appear that in the case of water, fast burn-out is nearly always associated with subcooled or low-quality conditions at burn-out. 

Substances applied to or incorporated in a combustible material (e.g. organic polymers, nylon, vinyl and rubber, etc.) to reduce flammability. Act by retarding ignition, control/douse burning, reduce smoke evolution. Slow down or interrupt the self-sustained combustion cycle when the heat-flux is limited. Flame retardants (FRs) improve the combustion behaviour and alter the combustion process (cool, shield, dilute, react) so that decomposition products will differ from nonflame retarded articles. FRs are usually divided into three classes ... 

The PSM Rule requires all PrHAs to address "any previous incident which had a likely potential for catastrophic consequences in the workplace," 29 CFR 1910.119(e)(3)(ii). An incident is an unplanned event that may or may not result in injuries and/or loss. For example, an incident might involve a flammable gas leak that does not ignite. An accident, on the other hand, is an unplanned event that actually leads to personal injury, property damage, environmental damage, and/or business interruption losses, such as the ignition of a flammable gas leak resulting in burns and fire damage. 

Fig. 7.27 Burning rates of LiF-catalyzed AP composite propellants, showing that the burning rate decreases and the pressure of self-interruption increases with increasing concentration of LiF.

In practical applications, some lamps, notably medium-pressure mercury lamps, cannot be started or restarted instantaneously and need some time to be re-striked. Interruption of lamp action would be totally unacceptable in continuous production. Moreover, the heat from burning lamps could cause deterioration of the substrate if... 

The lamp black process is only partially continuous. The feedstock, oil with a high aromatic hydrocarbon content, is burned in flat steel vessels up to 1.5 m in diameter (Fig. 56). The oil is continuously introduced into the vessel to keep a constant feedstock level. The off-gas containing carbon black is sucked into a conical exhaust pipe, which is coated with a ceramic inner liner and leads to the collecting system. The properties of the carbon black can be influenced to some extent by variation of the distance between the vessel and the exhaust and the amount of air sucked into the apparatus. One lamp black apparatus can produce 100 kg/h. The production process must be interrupted at certain time intervals to remove coke-containing residues from the vessels. 

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