Furnace configuration

Modern central stations use the other burner-furnace configurations shown in Fig. 27-16, in which the coal and air are mixed rapidly in and close to the burner. The primary air, used to transport the pulverized coal to the burner, comprises 10 to 20 percent of the total combustion air. The secondary air comprises the remainder of the total air and mixes in or near the burner with the primary air and coal. The velocity of the mixture leaving the burner must be high enough to prevent flashback in the primaiy air-coal piping. In practice, this velocity is maintained at about 31 m/s (100 ft/s). 

S. Boschert, P. Dold, K. W. Benz. Modelling of the temperature distribution in a three-zone resistance furnace influence of furnace configuration and ampoule position. J Cryst Growth 7S7 140, 1998. 

For vertical gas flow, which may be preferred in certain furnace configurations, vertical catalyst slabs can still be used when the bottom and top ends are tilted at an angle greater than the angle of repose of the solid material. Thus, gravity discharge of fouled catalyst material is possible, as illustrated in Fig. 23. 

As a result, the substitutional carbon and SiC particle distributions are obtained in a cross plane of the solidified ingot as shown in Fig. 4.8. Both substitutional carbon and SiC particles are clustered in a smaller periphery-top region of the ingot. This indicates that we can control the distributions of impurities in the solidified ingot by optimizing the process conditions or furnace configurations. 

For instance, post combustion in the headspace of the furnace (i.e., heat transfer to both scrap and flat bath surfaces) and in the slag layer (heat transfer to slag and slag-metal interaction) must be understood and addressed for specific equipment and furnace configurations. Furthermore, the process control mechanisms (vis-a-vis response times and oxygen utilization) and equipment utilized to effect the post combustion are critical to its viability. 

The wide variety of DTA furnace configurations is shown in Figure 6.10. 

Due to the NO stratification observed in the convection section of the lab furnace, one cannot conclude with certainty that the ghost NO anomaly was observed. The field tests, however, appear to indicate the ghost NO anomaly. This is at least in part likely due to catalytic decomposition of NO2 through the convection section. Other causes are also possible. It is recommended that additional tests be performed. One test might include testing in another furnace configuration. Another could be with different burner types. Measurements of other species (e.g., N2O) may also produce useful information that can be used to isolate the source of the additional NO. ... 

---