Cross-fired furnaces

An early configuration of the LTS-100 was tested in January 2005 in an oil-fired float glass furnace that used a cross-fired furnace with regenerative heat recovery (Jenkins and Bergmans 2005). Figure 14.13 shows a... 

Figure 9. OENR configuration for cross-fired furnaces...

Figures 3 and 4 show under port combustion in an end-fired and cross-fired furnace. This modelling confirmed it was possible and desirable to combine the conventional firing system with the Auxiliary combustion process, thus providing flexibility and the possibility of optimising the performance of the two systems.

Figure 4. Acid/Alkali model of under port flames in a Cross-fired furnace...

Because end-fired furnaces have very different and more complex flow patterns compared with cross-fired furnaces, the model studies were repeated for typical end-fired furnaces. A one fifth scale pilot End fired furnace was constructed in the GDF SUEZ-CRIGEN test facility (Figure 11) with a heat input of 500 kW. The design was based on the furnace on which the Industrial tests will be carried out. 

Heat transfer to the hearth ("glass") varied depending on configuration although there was a general trend towards greater efficiency (see Figure 14) as the auxiliary injection increased as had been observed on the 2MW pilot "cross fired" furnace. 

The furnace chosen for these tests is 600 t/d Float glass furnace using dual impulse side of port neck burners. The tests on the cross-fired furnace are expected to be carried out in November 2014. The basic testing procedure and measurements will be the same as for the End port furnace except that the injection must be applied to each port. A single port trial will be carried out before converting the remaining ports. 

Although testing had already been carried out on the GDF SUEZ Cross firedZMW pilot furnace that simulates a single port, it was important to understand the effect of the interaction between ports of a multiport furnace. To this end an Acid/Alkali model of the cross-fired furnace to be tested was buQt. This revealed the criticality of location and operating parameters of the Auxiliary Injectors on this type of furnace. It also suggested the changes that may be required to the operation of the side of port neck burners, which may be required when Auxiliary injection is applied. 

Cross-fired Furnace. A glass-tank furnace heated by flames that cross the furnace perpendicular to the direction of flow of the glass the furnace has several pairs of ports along its melting end (cf. 

End Feather. See feather brick. End-fired Furnace. A type of glass-tank furnace in which the ports are in the back wall (cf. cross fired furnace). 

Furnace A" has been continuously operated since January 2012, also producing high quality, low iron, soda lime glass for tableware production, utilizing a carbon/sulfate fining system. Furnace A is a five (5) port cross-fired furnace, which is electrically boosted and utilizes one (1) burner per port, with independent flow control to each of these ports. The typical pull rates are between 160 and 230 US tpd. The cullet ratio is 18% to 28%. 

Both tanks of the cross-fired furnace (Fig. 3.11) are standing on steel supports and the walls are fixed by rods. The flames generated by the burners (3) cross the melt level at a right angle to the melt stream in the melt basin (1) and leave the room above the glass level through the opposite burner port. The... 

Fig. 3.11. Two-house fuel oil heated cross-fired furnace having two tanks for melting and conditioning or working (N511e, 1978), where 1 is melting basin, 2 is the conditioning zone (working chamber), 3 is the burners, 4 is the regenerator or checker chamber, 5 is the doghouse or charging station and 6 is the throat...

FIG. 96. A cross-fired tank furnace for container glass production (after Gunther, 1954, niedified). 

Conversion to full oxy/fuel also provides an opportunity for production increase. The change in pull rate achieved with an oxy/fuel furnace, in comparison with an air/fuel furnace, varies depending on furnace type. Pull rate increases of up to 60% have been observed for unit melters. Cross-fired regenerative furnaces have seen increases as little as 10%. End-fired regenerative furnaces converted to oxy/fuel increase pull capacity by 20%. Recuperative melters typically achieve a 30% pull rate increase. 

CROSS-FIRED FLOAT GLASS FURNACE APPLICATION... 

Similar instrumentation to that used on the cross-fired pilot furnace was used. Testing the proposed auxiliary combustion injectors suggested by the acid/alkali modelling demonstrated that significant NOx reduction could be achieved as shown in Figure 13. 

Funding provided by the EU FP7 programme allowed two commercial glassmakers to join the development thus providing facilities for industrial testing of the process. One glass makers could test on two end-fired container furnaces fitted with dual impulse under port burners and the other could test on an Cross fired float furnace fitted with side of port neck dual impulse... 

Furnace type Five ports cross fired... 

Cross Section of Open Hearth Furnace Tap Hole Showing Jet Tapper in Position for Firing... 

Fire 1.4. Steam boiler and furnace arrangements. [Steam, Babcock and Wilcox, Barberton, OH, 1972, pp. 3.14, 12.2 (Fig. 2), and 25.7 (Fig. 5)]. (a) Natural circulation of water in a two-drum boiler. Upper drum is for steam disengagement the lower one for accumulation and eventual blowdown of sediment, (b) A two-drum boiler. Preheat tubes along the Roor and walls are cormected to heaters that feed into the upper drum, (c) Cross section of a Stirling-type steam boiler with provisions for superheating, air preheating, and flue gas economizing for maximum production of 550,000 Ib/hr of steam at 1575 psia and 900°F. 

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