Flames luminosity

The fire ha2ard of methanol appears to be substantially smaller than the fire ha2ard of gasoline, although considerably greater than the fire ha2ard of diesel fuel. The lack of luminosity of a methanol flame is stiH a concern to some, and M85 (or some other methanol fuel with an additive for flame luminosity) may become the standard fuel for this reason. 

Methanol, a clean burning fuel relative to conventional industrial fuels other than natural gas, can be used advantageously in stationary turbines and boilers because of its low flame luminosity and combustion temperature. Low NO emissions and virtually no sulfur or particulate emissions have been observed (83). Methanol is also considered for dual fuel (methanol plus oil or natural gas) combustion power boilers (84) as well as to fuel gas turbines in combined methanol / electric power production plants using coal gasification (85) (see Power generation). 

Luminous Flames Luminosity conventionally refers to soot radiation it is important when combustion occurs under such conditions that the hydrocarbons in the flame are subject to heat in the absence of sufficient air well mixed on a molecular scale. Because soot parti-... 

A bluff-body stabilized flame of CH4/H2 in air (designated HMl by Dally et al. [22]) (a) time-averaged photograph of flame luminosity, (b) time-averaged streamlines from LES, (c) instantaneous visualization of OH "luminosity" from LES, and (d) instantaneous temperature field from LES. (b and d are adapted from Raman, V. and Pitch, H., Combust. Flame, 142,329,2005. With permission.)... 

For premixed fuel-air systems, results are reported in various terms that can be related to a critical equivalence ratio at which the onset of some yellow flame luminosity is observed. Premixed combustion studies have been performed primarily with Bunsen-type flames [52, 53], flat flames [54], and stirred reactors [55, 56], The earliest work [57, 58] on diffusion flames dealt mainly with axisymmetric coflow (coannular) systems in which the smoke height or the volumetric or mass flow rate of the fuel at this height was used as the correlating parameter. The smoke height is considered to be a measure of the fuel s particulate formation and growth rates but is controlled by the soot particle bumup. The specific references to this early work and that mentioned in subsequent paragraphs can be found in Ref. [50],... 

Bundy et al (Ref 13) measured the velocity and pressure of gases in a rocket flame by determining the small shift in wavelengths of the flame luminosity with a Fabry-Perot interferometer... 

M85 is used to represent a fuel blend of 85% methanol and 15% gasoline. The gasoline portion is added for cold-start and flame luminosity reasons. 

E85 is used to represent a blend of 85% ethanol and 15% gasoline. The gasoline is added primarily for cold-start purposes, and contributes to greater flame luminosity. 

Temperature Bright and/or part icle-laden flame zones CARS Accomplished Strong signal Tolerates particle loading and strong flame luminosity More difficult to instrument and interpret than RS... 

Luminous Flames Luminosity conventionally refers to soot radiation. At atmospheric pressure, soot is formed in locally fuel-rich portions of flames in amounts that usually correspond to less than 1 percent of the carbon in the fuel. Because soot particles are small relative to the wavelength of the radiation of interest in flames (primary particle diameters of soot are of the order of 20 nm compared to wavelengths of interest of 500 to 8000 nm), the incident radiation permeates the particles, and the absorption is proportional to the volume of the particles. In the limit of rjX < < 1, the Rayleigh limit, the monochromatic emissivity e is given by... 

Flames from solid fuels may contain ash particles, which can glow, adding to the flame s luminosity. With liquid and gaseous fuels, flame luminosity usually comes from glowing carbon and soot particles. The effective flame emissivity, as measured by Trinks and Keller, is usually between that of the poc gases and a maximum value of 0.95, depending on the total surface area of solid particles. 

When the amotmt of an agent applied to a burning polymer is close to the amount required for flame extinction, first flame instability sets in, followed by flame liftoff from the surface and finally the flame is extinguished, as indicated in Fig. 53.7 for the flame extinction of PMMA by Halon 1301. Initially there is a rapid decrease in the chemical heat release rate as Halon is added to the flame. There is a gradual increase in the chemical heat release rate between 5.40% and 6.25% of Halon unto flame extinction. The increase in the chemical heat release rate appears to be due to increase in the flame luminosity (increase in the flame radiative heat flux transferred back to the fuel surface). 

Kiovsky, T. E. Clark, W. L. Methanol fuel containing flame luminosity agent. US Patent 5147413, 1992 Chem. Abstr. 1993,118, 128051. 

In conclusion, the FlammaTec Flex Burner has truly independent gas flow adjustment for both the inner and outer burner nozzles. Thus, the burner offers improved flame shape control, and therefore tighter flame stability, which yields more flame luminosity and therefore improved furnace operational performance. The improved flame shape control, and therefore excess oxygen levels within the furnace can yield improved energy efficiency. 

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