Figure 7. The Firing zone: dependence of the maximum temperature of the
pellets on the gas temperature and the gas flow rate within the layer
(layer top, middle and bottom)
Thus, at the gas flow rate of 0.8 m/s the temperature of pellets was registered as
high as 1214
o
C while at the gas flow rate of 1 m/s the temperature of the pellets was
1243
o
C.
General changes in the pellets maximum temperature were more notably observed
under conditions of the gas flow rate altering and the pellets moving within the depth
of the layer. However, the pellets exposed on the top of the layer, did not have changes
in their temperature at the large extent.
Analysis on the mutual influence of the gas temperature in the cooling zone
and the gas flow rate on the pellets cooling rate. The initial data for the analysis of
this kind was considered to be rational if the following values: the rate of gas filtration
in the cooling zone was 0.8 m/s; 1.0 m/s and 1.2 m/s; the depth of the pellets layer was
300 mm; the length of the cooling zone was 30 m; the velocity of the carriages was
2 m/s; the gas temperature in the cooling zone was 20
o
C, 60
o
C, 100
o
C. The data
obtained with this study are presented in Table 7.
In the course of the study, the temperature for the pellets firing was taken as high
as 1280
o
C, and the gas flow rate in the firing zone was 1 m/s.
In the cooling zone, it has been established that at all the cooling temperatures and
at all gas flow rates, the cooling rate of the pellets was less than 100 deg/min, that is, it
did not exceed the permissible value (Fig. 8).
Upper of the layer
1220
1240
1260
1280
1300
1220
1240
1260
1280
1300
Temperature of firing (°C)
T
em
p
er
ature
of
p
ell
ets (
°C)
1,2
1
0,8
Middle of the layer
1200
1220
1240
1260
1280
1220
1240
1260
1280
1300
Temperature of firing (°C)
T
e
m
p
e
r
ature
of
p
ell
ets (
°C)
1,2
1
0,8
Bottom of the layer
1160
1180
1200
1220
1240
1260
1220
1240
1260
1280
1300
Temperature of firing (°C)
T
e
m
p
e
r
ature
of
p
ell
ets (
°C)
1,2
1
0,8
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