Delayed mixing

Low-NO burners are designed to delay and control the mixing of coal and air in the main combustion zone. A typical low-NO air-staged burner is illustrated in Fig. 24-16. This combustion approach can reduce NO emissions from coal burning by 40 to 50 percent. Because of the reduced flame temperature and delayed mixing in a low-NO burner, unburned carbon emissions may increase in some apphcations and for some coals. Overfire air is another technique for... 

Milton, J., VanDerHeiden, U., Longtin, A., and Mackey, M., Complex dynamics and noise in simple neural networks with delayed mixed feedback, Biomedica Biochimica Acta, Vol. 49, No. 8-9, 1990, pp. 697-707. 

Calzolai et al. have used and NMR to study the paramagnetic cluster environment of ferredoxin from the hyperthermophilic archaeon, Pyrococcus furiosus. They identified dipolar connectivities involving the strongly relaxed residues near the metal centers by a combination of Ti data, rapid pulsing and/or short delay/mixing time H WEFT spectra, NOESY, TOCSY, and HSQC maps. 

Luminous flames often have been chosen because the added length of the delayed-mixing luminous flames can produce a more even temperature distribution throughout large combustion chambers. As industrial furnaces are supplied with very high combustion air preheat or more oxy-fiiel firing, luminous flames may enable increases in... 

If air and fuel are premixed upstream of a burner nozzle, mixing (and therefore combustion) may occur more rapidly than with nozzle mixing, and surely more thoroughly than with delayed mixing (perhaps with a detached flame) out in the furnace. Presumably, faster mixing and combustion will require less furnace volume, but the aerodynamics and the directions of the velocity vectors can influence flame shape to the point where flame volume may be less dependent on air or fuel momentum. 

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. 

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