Environmental Engineering Reference
In-Depth Information
5
10
5
10
4
10
4
10
3
10
3
10
100
100
10
10
0
200
400
600
800
1000
1200
1400
1600
Atmospheric gas temperature in furnace,
°
C
Continuous heating furnace
Batch type heating furnace
Ladle
Continuous heat treatment furnace
Batch type heat treatment furnace
Gas treatment furnace
Melting furnace
FIGURE 5.87
Relation between atmospheric temperature in furnace and amount of energy
saving.
The legally permitted values of NO
x
emissions vary with the type and capacity
of furnaces.
Table 5.30
shows the typical legal restriction values concerning the 58
furnaces included in the field test project. Many local governments have designated
standard values in excess of these restriction values, which are problems for facility
operators. Because facility operators see no point in lowering their NO
x
emission
levels below the current legal restriction values or standards, it is beyond the scope
of the work of this field test project to define clearly the technological capacity of
TABLE 5.30
Legal Restriction Value of NO
x
Conversion
O
2
, %
Legal Restriction
Value, ppm
Items
Notes
Heating F
11
100-180
In some localities within the
metropolitan area, strict values
lower than
1
/
3
of the legal restriction
values are applied
Heat treatment F
11
80-180
Melting F
12
130-200
NO
x
ppm: C = (21 - O
n
)/(21 - O
s
) × C
s
O
n
= Conversion O
2
%
O
s
= Measured O
2
%
C
s
= Measured NO
x
ppm
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