Rectangular burner

FIGURE 5.2. Photograph of a natural gas-air flame on a rectangular burner, with very small magnesium oxide particles introduced into the flow and illuminated stroboscopically in order to make the gas streamlines visible (from [11], courtesy of B. Lewis and of Academic Press). 

The same conclusion can be made based on the turbulent flame velocities measured by the other method (in a rectangular burner) [11] and illustrated in Fig. 3.8. Let us note the high Sx/S ratio in the lean mixture with less than 13.7% H2 at a turbulent intensity u = 10 m/s. The attempt to summarize the measured results and to verify the possibility of natural turbulence generation by the flame was made in [11]. 

In fuel-lean premixed burners, the primary air ratio determines the quality of combustion changing the rotational speed of the flue gas fan has also some influence. An ionization probe is used to determine the quality of combustion. A dedicated system, developed at GWI, provides accurate detection and analysis of the ionization signal. This includes a metering device, which is provided with a rectangular supply voltage, thus warranting very accurate ionization signals. 

Flame atomisation. A burner is fed with a combustible gas mixture and constructed in a robust fashion to resist possible explosions of the gas (Fig. 14.8). The flame, which has a rectangular base of approximately 10 cm by 1 mm is aligned with the optical axis of the instrument. The sample is aspirated by the Venturi effect into the mixture of combustible gases feeding the flame. 

The absorption cell was made of rectangular-section Plexiglas of dimensions 17 cm x 3.3 mm x 5 mm (the 5 mm section being mounted vertically) (see Fig. 7.2). The cell had an internal volume of 2.8 ml and two quartz windows were attached to its ends with epoxy cement. The cell was fixed on a metal support, which in turn was fitted to the burner support hole. The inlet and outlet ports (2 mm id) were about 2 mm from each end of the absorption cell. A windowless cell with similar dimensions was also made, but the inlet port was in the middle of the cell. 

There are two primary shapes for fhe ouflef nozzle of industrial burners round or rectangular. Figure 1.41 shows identical heaters with the same number of burners, but with different burner shapes round flame and flat flame. Round flames are fhe predominant shape used in industry. Most of the burners discussed in this book are predominantly round. This is often due to the lower cost of making round shapes compared to making rectangular shapes. It is also often due to the burner tile where round shapes generally require less maintenance... 

Most cover annealers are single stack furnaces, but there are some multistack annealers with three, four, six, or eight stacks, each with a bell cover, all within one rectangular furnace. (Radiant tubes were used in addition to the inner covers in the past because of poor heating between the inner covers.) Now, type H high-velocity burners are fired down or up between the inner covers. 

Molten zinc for galvanizing (surface oxide emissivity 0.1) is contained in open-topped, rectangular steel tanks or kettles, with walls of 1" to 2" boiler plate or firebox steel. Test data on the tank shown in figure 3.28 (reference 49) showed that the container wall temperature was more uniform with four type H flames than with 18 type E flames (fig. 6.2), but such comparisons are highly dependent on burner spacing, burner size, and distance from container to wall. 

Fig. 4.25. Forced draft heater for petro-chem processing—may be cylindrical with one burner as shown, or a circie of vertically up-fired, high-velocity type H burners (fig. 6.2) or rectangular (a cabin heater) with rows of up-fired burners, or rows of side-fired type E flat-flame burners, shown in fig. 4.26 and 6.2.

ISO 340-1982 concerns the flammability testing of conveyor belts. A rectangular test piece 200 mm x 25 mm is arranged with its major axis vertical and then ignited at its lower edge by a 150 to 180 mm long spirit flame from a burner inclined at 45 deg. for 45 s (Fig. 3.136). The duration of flaming after removal of the burner is measured. 50 to 70 s after removal of the burner, an air stream is directed at the surface of the specimen at a speed of 1.5 m/s and it is observed whether or not the specimen flares up. 6 specimens are cut, 3 warp way and 3 weft way. If covered belts are tested, 6 additional test pieces are prepared in the same manner but the covers are stripped off. The material meets the requirements if the total duration of flame... 

In view of the cheaper building costs, modern kilns are more likely to be rectangular than round, the air will be heated either by an open-flame oil burner or by a closed stove and either forced or drawn through the bed of hops with a powerful fan. Air speeds of about 15 m/min (50 ft/min) are normal, although up to 30 m/min (100 ft/min) have been used. Above this speed dried bracts may be blown off the kiln. Using these higher air speeds much... 

The furnace is rectangular in shape with a shallow hearth and arched roof. The floor and roof slope down to the firing end, and the opposite end contains a feeding port where the feed mix is continuously or intermittently pushed into the furnace. A natural gas or oil burner flame extends to the... 

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