Flame Types

Flame Types and Their Characteristics. There are two main types of flames diffusion and premixed. In diffusion flames, the fuel and oxidant are separately introduced and the rate of the overall process is determined by the mixing rate. Examples of diffusion flames include the flames associated with candles, matches, gaseous fuel jets, oil sprays, and large fires, whether accidental or otherwise. In premixed flames, fuel and oxidant are mixed thoroughly prior to combustion. A fundamental understanding of both flame types and their stmcture involves the determination of the dimensions of the various zones in the flame and the temperature, velocity, and species concentrations throughout the system. 

It may be expected, then, that the nature of the various turbulent flows, and indeed the structures of turbulent flames, may differ considerably and their characterization would depend on the comparison of these chemical and flow scales in a manner specified by the following inequalities and designated flame type ... 

For a better understanding of this type of flame occurrence and for more explicit conditions that define each of these turbulent flame types, it is necessary to introduce the flame stretch concept. This will be done shortly, at which time the regions will be more clearly defined with respect to chemical and flow rates with a graph that relates the nondimensional turbulent intensity, Reynolds numbers, Damkohler number, and characteristic lengths /. 

HEATER, Flame-Type or Electric Resistance Type (Flame Type shown)... 

Sample and treatment Li found (Fg/g) Analytical method Flame type... 

Acid sludge Cone and flat-flame type burners, steam-atomized 10-15... 

Recommended Wavelength, Flame Type, and Technique for Flame Atomic Absorption Analysis... 

Coal combustion processes can be classified based on process type (see Table 9.1), even though classification based on the particle size, the flame type, the reactor flow type, or the mathematical model complexity is also possible [7]. 

Basically, all the above tests evaluate the flaming tendency -- e.g., flame type, flame spread, flame duration, etc. 

Flame Type Experimental Measurement Range (K) Calculated Stoichiometric Temperature (K) Typical 1 (K)... 

The elements, absorption lines, flame types, and interferences associated with the analysis by P CAM 173 will be discussed and contrasted to other methods for these elements. Thirty-one metals are analyzed by P CAM 173 five metals, Al, Be, Co, Cr, and V are listed as potentially only partially digested by nitric acid and Ni, Sb, and Sn may need more vigorous oxidation than just nitric acid. 

Selenium. Selenium has been determined colorimetrically by formatrion of a diaminobenzidine complex, 420 nm, after an oxidation and distillation (13). Method S-190 for selenium in air extracts the analyte from filters by 0.1 N nitric acid leaching. The nitric acid extracts are aspirated into an argon/hydrogen-air flame, and the absorbance is recorded for the 196 nm analytical line. The method discourages the use of a carbonaceous flame like air-acetyelene. Many analysts use air acetylene because it is convenient. Background correction is required for either flame type. 

Examining the detailed chemical processes of soot formation and oxidation, one notes how very complex the overall system is. Regardless of the flame type, the fuel undergoes either pure or oxidative pyrolysis. If the fuel is nonaromatic. 

The tool used to produce flames suitable for working glass tubes is variously named torch, burner, blowpipe, lamp, cannon, fire and gun. In the interests of simplicity that used for bench work will be referred to as a bench burner or a burner that used in the hand will be called a handlamp or a lamp. The multiple flame type of burner is used in some workshops for bench work and is universally used for working glass in a glassblower s lathe they will be referred to as crossfires and are shown in Plate 4.5. 

Although sometimes differentiated from spray pyrolysis, aerosol assisted CVD is essentially the same motif. It is, however, typically not conducted in a flame type regime. Nevertheless, frequently, materials are not transported perpendicular to a substrate surface, thereby bypassing one of the crucial elements of chemical vapor deposition - the ability to secure extraordinary step coverage in high aspect ratio materials, due to the non-line-of-sight technique. 

Since both the flame-photometric and thermionic detectors are the flame-type detectors, similar rules apply for their coupling with capillary columns as for the flame ionization detector no special modifications are required. 

A number of instrumental parameters will affect precision and sensitivity in these atomization techniques. In both systems, bandpass (slitwidth) and lamp current must be optimized. In flame AAS, the other operating parameters are burner height,burner alignment, fuel flow, flame, type, and... 

For flame types, see fig. 6.2.) Unlike crucible, pot, kettle, and dip-tank furnaces, the refractory furnace lining itself is the container for glass tanks and aluminum melting furnaces, figure 1.2. 

In a laminar flame, thermal expansion from chemical heat release may combine with increased reactivity caused by higher temperatures, resulting in acceleration to a turbulent flame. Except for long luminous flames, most industrial flames are turbulent. (See fig. 6.2 for descriptions of a number of generic industrial flame types see also... 

Fig. 3.14. Heat treating furnace with radiant U-tubes on the roof and back wall. The return legs (2nd and 4th from the hearth) are less radiant than the burner legs (1 st and 3rd from the hearth). Tumbling around the bends completes gas-air mixing so the renewed delayed-mixing flame (type F, fig. 6.2) causes a glow in the second leg. Courtesy of Rolled Alloys, Temperance, Ml.

Rg. 3.15. Evolution of gas-fired radiant tube flames, a = premix flame, open burner, b = nozzle-mix flame, sealed-in burner, c = long, laminar, delayed-mix flame (type F) sealed-in. d = partial premix, followed by long, laminar, delayed-mix flame, sealed-in. 

Fig. 4.16. Modern skelp-heating furnace with heat recovery by load preheating. Some furnaces use type H high-velocity impinging burners others use refractory radiating burners similar to type E, but with concave refractory tiles. (See fig. 6.2 for these flame types.)...

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