Radiation zone

The release of chemical energy during combustion of gases produces a luminous, radiating zone which is seen as the flame or flame front. ... 

For a jet fire close to obstacles but not impinging on them, the flame shape will be similar to free-field predictions, but the radiation field will be distorted. A simple judgmental representation of the effects of obstacles on the radiation zones is described below ... 

Solid obstacles such as walls on enclosed spaces are considered impervious to thermal radiation, and are assumed not to affect the radiation zones outside them. 

Partial obstacles such as process equipment or decks on open-sided modules are approximated by reducing the radiation zones as follows ... 

When we are far from sources in the radiation zone, the amplitudes of electric and magnetic fields verify the equality E2 = B2. 

Fig. 8 Schematics of the radiation zone, showing the high energy electrons scanned through the electron accelerator (ELV-2)...

Far-field region or radiation zone, defined by R > r7. At macroscopic distances, the longitudinal component of force is negligible, so that the radiation field is almost plane (i.e., perpendicular to the z-axis in Fig. 3). 

The preheater of the gaseous EDC is integrated in the convection zone of the furnace. The pyrolysis reactor is placed in the radiation zone. The design of the furnace is a complex aspect not treated here, in which heat integration plays an... 

A physical interpretation of Equation (35) is possible if one notes that it is mathematically analogous to Fourier law of heat conduction. The constant factor in the right-hand side plays the role of thermal conductivity, and the local incident radiation GA(r) plays the role of temperature. In that sense, differences in the latter variable among neighboring regions in the medium drive the diffusion of radiation toward the less radiated zone. Note that the more positive the asymmetry parameter, the higher the conductivity that is, forward scattering accelerates radiation diffusion while backscatter-ing retards it. 

Figure 2.11 show s a highly simpUhed flow sheet of such a fecility for the case of naphtha feedstock. It features a number of furnaces, quench boilers, and a highly complex fractionation train. The hydrocarbon feedstock enters the hot section of the unit through the convection zone of the furnace, where it is preheated (part 11 and is then mixed with steam that is also preheated in this zone. The hydrocarbons and water pass through the radiation zone of the furnace (part 2k w here the rapid temperature rise and pyrolysis reactions take place. At the furnace exit, in order to avoid any subsequent reaction, the... 

As a rule, the feed is preheated to about 400 in the convection zone, by the heat from the hot gases leaving the furnace. It is then mixed witii dSueat steam, and then enters the radiation zone, where it is raised to over SOC XT in three to four tenths of a second. The energy efficiency of a furnace is about 85 per cent and the quantities of heat supplied in the convection and radtation zones are 47 and 53 per cent respectively. In the radiation zone, the temperature profile of the steam/hydrocarbon mixture is regulated by adjusting the beating intensity of the rows of burners. 

To provide an example. Fig. Z16 shows a sin libed isometric view of a cell of a steam cracker with vertical tubes in the radiation zone and horizontal tubes in the convection zone. It also shows the positions of the adewaU burners, quench boilers, steam drum, and the injection device of the heavy cut which performs the supplementary direct quench. 

For smaD diameter tubes which are fouled more rapidly, the increase in pressure drop is the decoking criterion, whereas, for larger>skin temperature of the tube in the radiation zone whidi indicates the degree of fouling. 

The following balance equations are valid for this hollow enclosure with three black radiating zones ... 

The products leaving the furnace radiation zone must be cooled as quickly as possible This operation is designed in particular to prevent the effluent composition from changing by the formation of heavy polymerization products and the increase in the gasoline content. It is important for the transfer line between the furnace and the quench boiler to be as short as possible to avoid additional residence of the effluents at elevated temperature. The heat of the furnace is fust recovered by indirect cooling in the quench boilers, and directly by the introduction in-line of a recycle using a heavy hydrocarbon cut called quench oil Fig. 2.11). 

Eq. (18) and the validity of the pole approximation). It demonstrates that in the radiation zone the electromagnetic field energy is concentrated completely in the polarization direction e. Integrating Eq. (28) over all space (thereby neglecting contributions outside the radiation zone) the electric field energy at time t is given by... 

The preheated reaction feed first goes into a convection zone, which is heated by the burned gases, then into a radiation zone where it is heated by radiation and convection it is cooled quickly and fractionated at the exit to the chamber. 

The explosion and a fire at the plant s fourth reactor on April 26 last year killed 31 people, forced the evacuation of 135,000 residents from high radiation zones around Chernobyl, and spread radiation across much of England and Europe. 

For in-reactor surveys the need to enter contamination and radiation zones considerably reduces operator efficency. In a typical 8 hour day up to 4 hours may be spent in preparation and decontamination and the protective clothing worn restricts motion and vision such that the operator probably works at only half normal pace. In addition,... 

TV cameras have been developed for a wide variety of hostile environments and are applicable to refueling. They represent an dtemative optical meftiod but will not provide the clarity of view of precision metrology. Specialized TV cameras such as fiberscopes have been developed with high radiation resistance and enable the electronics to be positioned in cooled low-radiation zones. 

The extended plasma has two zones, referred to as the initial radiation zone, where atomization has occurred, and the normal analytical zone, where ionization is complete. As the name indicates, the latter zone is preferable for spectrophotometry or ion extraction. The zones can be visualized by introducing yttrium into the plasma. Atoms of Y and molecules of YO emit red light in the initial radiation zone. Ionization to the blue-emitting Y ion causes the normal analytical zone to appear blue. 

The areas adjacent to the reactor are. In turn, surrounded by secondary shielding walls These help maintain radiation levels below 0 1 mr in continuously occupied areas of the reactor building, and less than one mr/hr. In less frequently occupied areas which may be entered or passed through without radiation zone procedures ... 

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