Environmental Engineering Reference
In-Depth Information
0.70
0.65
Furnace height of
conventional furnace
0.60
2
2.5
3
3.5
4
Furnace height m
F
IGURE 5.2
Furnace height and heating ef
ficiency.
5.1.3
O
D
O
F
C
PTIMAL
ESIGN
FOR
THER
URNACE
ONFIGURATIONS
5.1.3.1
Pitch and Capacity of Burner
In the design of a high performance furnace, not only the dimensions, b
ut also the
capacity and installation pitch (the number of burners installed) of the burners are
crucial. The effect of burner pitch on the heating efficiency was tested with a doubled
burner pitch by using each of four pairs of burners installed in the furnace length
direction. As shown in Figure 5.3 , the heating efficiency and combustion load were
found to be negatively correlated. Presumably this is because the high temperature
region expanded in the furnace width direction as the combustion load of burners
increased to finally increase the temperature of the zone close to the wall on the
other side of the burners. It is also shown that there is an optimal burner capacity
with respect to a given furnace width, because the heating efficiency was lowered
when the combustion load was too small and the in-furnace temperature in the center
position became high. The in-furnace temperature distribution in high temperature
air combustion was flattened more than in the conventional method. However, it is
also true that a gap in temperature was generated between the burner center axis
and the burners. So it is necessary to determine the burner capacity with these
findings taken into consideration. According to the results of calculations, the optimal
burner pitch can be assumed to be about 18% of the furnace width.
5.1.3.2
Partition Wall
The ef
fect of the partition wall was examined by placing a partition between the
first zone and the second zone in such a manner that a combustion pattern with a
higher load occurred in the second step and was set up in the common test facility
II. With a partition wall used to separate the high temperature zone from the low
temperature zone and to block the transfer of gas and radiation of heat from gas
between the zones, the temperature of the high temperature zone can be considerably
raised with corresponding decreases in the low temperature zone. The results of the
 
 
Search WWH ::




Custom Search