High-momentum burners

Corrosion is caused by condensation of glass volatiles that have flowed into the burner region. If the burner is colder than the condensation point of the volatiles, the volatiles will condense on the burner and chemically attack the burner. This phenomenon is common for water-cooled burners since they are relatively cold and typically high momentum. High-momentum burners generally induce a flow pattern that promotes movement of the furnace gases back to the burner tip. To minimize this problem, non-water-cooled, low-velocity burners are recommended.11... 

The Duoflex burner of F.L. Smith is based on a novel concept featuring a central duct for gaseous and liquid fuels placed inside an annular coal duct. The Duoflex burner fires with all types of fuels and may also be fitted to AT. A high momentum burner, such as the Duoflex G2 burner depicted in Figure 31.15, which provides a vigorous mixing of the particles with the local atmosphere, increases the probability that the char particle will encounter oxygen to facilitate the quick burnout. 

Enhance furnace bottom temperature with many small high-velocity (high-momentum) burners, firing with constant air, variable fuel, that is, excess air as they turn to low fire, to hold the same temperatures below the load(s) as above. Install fuel meters on each zone. When the fbel flows in all zones reaeh their minimums, hold as long as necessary for the required minimum temperature differential between surface and core, as determined from time-temperature heating eurves. Then remove and process the loads. 

The early oxy/fuel projects used high-momentum water-cooled burners modified from applications in the metals industries. The experience with frit conversions and with the partial oxy/fuel conversions in other glass segments revealed the need for burners to be developed specifically for glass.2... 

If high-momentum oxy/fuel burners are used, the wall opposing the burner may overheat and damage may occur to the refractory.2 To minimize this problem, low-momentum burners are recommended. Overheating can still occur with low-momentum burners if the flame impinges on the opposite wall. In this case, the firing rate must be reduced. 

For medium or low temperature furnaces/ovens/dryers operating below about 1400 F (760 C), a forced recirculation furnace or recirculating oven delivers better temperature uniformity and better fuel economy. The recirculation can be by a fan and duct arrangement, by ceiling plug fans, or by the jet momentum of burners (especially type H high-velocity burners—fig. 6.2). 

Fig. 7.12. Top-side temperature uniformity is assured with adjustabie thermai profiie burners and two-sensor controi. High momentum, underioad burners (enhanced heating) with two-sensor con-troi improve bottom temperature uniformity.

Incorporate pulse firing, which takes advantage of all the energy of high fire velocity (momentum) in limited time firings instead of throttling burners to low... 

Figure 6.10 Acid-alkali modeling of combustion in rotary kilns (a) low burner momentum, (b) high burner momentum.

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