Environmental Engineering Reference
In-Depth Information
where ρ = 1.205
(kg/m
3
) and µ = 0.0180 × 10
-3
(Pa·s).
Correspondingly, the Re of the high performance heat treatment furnace is
Re
2
= 66944
V
× 1.55 = 30.8 × 10
(5.10)
If the average diameter of the heat-treating coil in the high performance furnace
is 1.55 m, then
D
2
/
W
2
= 1.55/
W
2
= 0.685
(5.11)
Consequently, the selection of fan capacity can be decided as
V
= 2.97
m/s from
Equation 5.10 and a high performance heat treatment furnace can be designed that
has the same characteristics of heat transfer as the test furnace by adopting the
furnace dimension of
W
2
= 2.26
m from Equation 5.11.
5.4.3.3 Test Design of Heat Treatment Furnace
This section discusses the design dimensions necessary for the actual RT-type heat
treatment furnace and, in particular, the design dimensions for general use on both
batch furnaces and continuous furnaces, as well as an outline of the heat treatment
that is applied based on the results obtained by development of the high performance
furnace. The heat treatment results in a 30% reduction in CO
2
, and in a low NO
x
level, which satisfy environmental regulation.
The features of minimum loss of waste gas and uniformity of RT temperature
are realized by using the RT-type regenerative burner. Minimum loss of waste gas
and uniformity of RT temperature are realized by using the RT-type regenerative
burner, and as a result maximum heat transfer to heating materials is obtained, as
well as optimum agitating fans in the furnace. Uniformity of convection heat transfer
in the surrounding heating materials is realized by using agitating fans, which
maintain uniform flow of the atmospheric gas in the heat treatment furnace. Unifor-
mity of temperature of both furnace and heating materials can be realized by means
of the above-mentioned features. Stable furnace operation and uniformity of RT
temperature can be realized by adoption of the heating control system suitable for
the RT-type regenerative burner.
The actual design method is outlined below:
1. The flow of design
(
Figure 5.72
)
2.
The study of user's specifications
a. Heat source: kinds of fuels, calorific values, supply pressure, etc.
b. Use materials for heat treatment: name, quality, and shape (maximum
size, minimum size, dimensions, and weight of standard materials)
c. Temperature: normal temperature, minimum temperature; objects to
be kept within the required temperature range, number of measuring
points, and measuring methods
d. Treating capacity: the specification of capacity is required in terms of
kg/h or t/h in the case of continuous furnaces and kg/batch or t/batch
in case of batch furnaces; if not, alternative terms (for example,
monthly treating amount and operation time) are required
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