Flame circular

In wetted-wall units, the walls of a tall circular, slightly tapered combustion chamber are protected by a high volume curtain of cooled acid flowing down inside the wall. Phosphoms is atomized by compressed air or steam into the top of the chamber and burned in additional combustion air suppHed by a forced or induced draft fan. Wetted-waU. plants use 25—50% excess combustion air to reduce the tail-gas volume, resulting in flame temperatures in excess of 2000°C. The combustion chamber maybe refractory lined or made of stainless steel. Acid sprays at the bottom of the chamber or in a subsequent, separate spraying chamber complete the hydration of phosphoms pentoxide. The sprays also cool the gas stream to below 100°C, thereby minimising corrosion to the mist-collecting equipment (typically type 316 stainless steel). 

In the simple Bunsen flame on a tube of circular cross-section, the stabilization depends on the velocity variation in the flow emerging from the tube. For laminar flow (paraboHc velocity profile) in a tube, the velocity at a radius r is given by equation 20 ... 

As for oil and gas, the burner is the principal device required to successfully fire pulverized coal. The two primary types of pulverized-coal burners are circular concentric and vertical jet-nozzle array burners. Circular concentric burners are the most modem and employ swid flow to promote mixing and to improve flame stabiUty. Circular burners can be single or dual register. The latter type was designed and developed for NO reduction. Either one of these burner types can be equipped to fire any combination of the three principal fuels, ie, coal, oil and gas. However, firing pulverized coal with oil in the same burner should be restricted to short emergency periods because of possible coke formation on the pulverized-coal element (71,72). 

Papirer et al. used ATR, XPS, and SIMS to determine the effect of flame treatment on adhesion of polyethylene and polypropylene to styrene/butadiene (SBR) rubber [8]. Each flame treatment consisted of a 75-ms pass over a circular burner. The distance between the upper flame front and the polymer was kept fixed al 8 mm. A band was observed near 1720 cm" in the ATR spectra and assigned to carbonyl groups this band increased in intensity as the number of flame... 

D) Steam Inspirated Air Type Circular ring flame... 

A massive amount of propane is instantaneously released in an open field. The cloud assumes a flat, circular shape as it spreads. When the internal fuel concentration in the cloud is about 10% by volume, the cloud s dimensions are approximately 1 m deep and 100 m in diameter. Then the cloud reaches an ignition source at its edge. Because turbulence-inducing effects are absent in this situation, blast effects are not anticipated. Therefore, thermal radiation and direct flame contact are the only hazardous effects encountered. Wind speed is 2 m/s. Relative humidity is 50%. Compute the incident heat flux as a function of time through a vertical surface at 100 m distance from the center of the cloud. 

Numerical simulation of a spirming detonation in Hj/air mixture in a circular tube at various times. Gray and green space isosurfaces in pressure are the detonation front and the pressure of 6 MPa. White arrow propagating direction of the detonation front, pink arrow rotating direction of the transverse detonation. TD—transverse detonation, and LT—long pressure trail. (Reprinted from Tsuboi, N., Eto, K., and Hayashi, A.K., Combust. Flame, 149,144,2007. With permission.)... 

N. Tsuboi, K. Eto, and A.K. Hayashi, Detailed structure of spinning detonation in a circular tube. Combust. Flame, 149, 144-161, 2007. 

For flame emission measurements, burners of the Meker type with a circular orifice covered by a grille are used whereas in atomic absorption spectrometry, a slit burner is preferred. In both cases, the flame consists of two principal zones or cones (Figure 8.21(b)). The inner cone or primary... 

Excitation of sample atoms by primary radiation from a high-intensity broad spectrum or element selective source. Samples atomized in a chemical flame using a circular burner. Optics to isolate emission line and photomultiplier to measure its intensity. 

Consider the ignition of a flammable mixture at the closed end of a horizontal circular tube of cross-sectional area A. The tube has a smaller opening at the other end of area A0. The process is depicted in the figure below. The flame velocity in the tube is designated as vf. It is distinct from the ideal burning velocity, Su, which is constant in this adiabatic case. The following assumptions apply ... 

It is estimated that in the WTC disaster that the jet fuel burned in one of the towers at 10 GW. If this is assumed to bum over an equivalent circular area constituting one floor of 208 x 208 ft, and would produce an unimpeded fire plume, then compute the height of the flame and the temperature at two diameters above the base. 

The preceding analyses hold only for circular fuel jets. Roper [10] has shown, and the experimental evidence verifies [11], that the flame height for a slot burner is not the same for momentum- and buoyancy-controlled jets. Consider a slot burner of the Wolfhard-Parker type in which the slot width is x and the length is L. As discussed earlier for a buoyancy-controlled situation, the diffusive distance would not be x, but some smaller width, say xb. Following the terminology of Eq. (6.25), for a momentum-controlled slot burner,... 

Oil Burners The structure of an oil flame is shown in Fig. 24-26, and Fig. 24-27 illustrates a conventional circular oil burner for use in boilers. A combination of stabilization techniques is used, typically including swirl. It is important to match the droplet trajectories to the combustion aerodynamics of a given burner to ensure stable ignition and good turndown performance. 

When a jet fire impinges on an object, its shape may be very distorted compared to the free-field shapes modeled. If the jet fire impinges perpendicularly on a flat object such as a fire-wall or deck, it will produce a thin circular flame over the object s surface. 

Figure 5.4 Schematic of the geometrical configuration for hydrogen-air flame and sofid fuel. The geometry corresponds to the experimental setup. The initial shape of the HED fuel was a circular arc segment as shown above. The relevant material properties air density = 1.91 kg/m , hydrogen density = 0.0898 kg/m . For the turbulent quantities at the inlet k = (O.OSf/miet) = 9.59 (m/s), = C fc / /(0.03Liniet) = 6360 m /s , jjkt = Cfe = 0.00248 kg/ms. For the fuel sample, m.p. is 450 K, latent heat of fusion is 72.7 J/g. Dimensions in mm. Air inlet velocity 103.3 m/s, hydrogen injection velocity 800 m/s...

There has been interest in the low radiative background, low quenching argon-hydrogen diffusion flame. The temperature of this flame is too low to prevent severe chemical interferences and therefore the argon-separated air-acetylene flame has been most widely used. The hot nitrous oxide-acetylene flame (argon separated) has been used where atomization requirements make it essential. In all cases, circular flames, sometimes with mirrors around them, offer the preferred geometry. 

The suspended flame rotary burner produces atomization of the oil by throwing it off as a spray from a cone, cup, or disk, rapidly revolving about a vertical axis. The spray is supported by the air stream and burns in a flat, circular flame. 

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