Industrial electric heating furnaces – Arc furnace device – Charging or discharging
Reexamination Certificate
2000-03-28
2001-01-23
Hoang, Tu Ba (Department: 3742)
Industrial electric heating furnaces
Arc furnace device
Charging or discharging
C373S020000, C373S033000, C373S080000
Reexamination Certificate
active
06178192
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a raw-material heating apparatus, and more particularly to a vertical-type raw-material heating apparatus for heating a raw material such as a raw ore prior to effecting heat treatment such as maturing.
2. Description of the Related Art
As an apparatus of this type, for example, one shown in the appended drawing
FIG. 5
is known. In this known apparatus, a heating section A is formed by an upper portion above a hearth
51
, while a vertical-type hollow cylindrical member
53
communicating with a lower portion therebelow by means of a drop port
52
in the hearth
51
is disposed below the heating section A so as to form a maturing section B for maturing and cooling the raw material.
The hearth
51
of the above-described known apparatus rotates about a vertical axis
58
A, and rod-like pushers (material pushing-in devices)
54
for allowing a deposited layer of a raw material M formed on a hearth surface
51
A to drop gradually through the drop port
52
which is open in the center are provided above the hearth
51
.
A heating gas (mainly a combustion gas) is supplied from a heating-gas blowing pipe
58
to a heating space
57
formed in such a manner as to be surrounded by a furnace cover
55
, a peripheral wall
56
, and the hearth
51
. The raw material M in a deposited layer surface M
1
on the hearth
51
is directly heated by the heating gas, and its temperature rises. The heated raw material M in the deposited layer surface over the hearth
51
drops into the vertical-type hollow cylindrical member
53
from the drop port
52
by the action of the pushers
54
, thereby forming a deposited layer M
2
inside the hollow cylindrical member
53
.
As also shown in
FIG. 6
, which is a cross-sectional view taken along VI—VI in
FIG. 5
, the aforementioned rod-like pushers
54
are provided at a plurality of circumferential positions (incidentally, in
FIG. 6
, the drop port
52
located below the cross-sectional line VI—VI in
FIG. 5
is shown by a two-dot chain line for reference sake). In the case illustrated in
FIG. 5
, the timings of operation of the plurality of pushers
54
are alternately staggered. Each pusher
54
has an effective region E for effectively feeding the raw material to the aforementioned drop port
52
through its movement in a direction toward the drop port
52
(in the longitudinal direction of the pusher
54
). An ineffective region N is formed between adjacent ones of the effective regions E. When viewed from above, raw-material supplying pipes
59
for supplying the raw material M onto the hearth
51
and exhaust pipes
60
are connected to the furnace cover
55
in such a manner as to be located in the aforementioned effective regions E and in the ineffective regions N, respectively.
Next, in
FIG. 5
, cooling air is supplied from below into the deposited layer M
2
inside the hollow cylindrical member
53
which forms the maturing section B. The raw material which constitutes this deposited layer M
2
drops while maturing by means of the heat which it possesses, is gradually cooled by heat exchange with the cooling air, and is removed as a product from a discharge port (not shown) in a lower portion of the hollow cylindrical member
53
. Meanwhile, the aforementioned cooling air rises through the aforementioned deposited layer M
2
while being heated by the raw material, and flows into the aforementioned heating space
57
in the state of increased temperature, thereby contributing to the combustion of the heating gas.
In addition, the heating gas inside the heating space
57
enters the interior of the deposited layer of the raw material M on the hearth
51
from the deposited layer surface M
1
, and after heating the raw material M in the interior, the heating gas passes through the exhaust pipes
60
, and is discharged to the outside as an exhaust gas.
With the above-described known apparatus and numerous other apparatuses similar thereto, the pushers are provided at a plurality of circumferential positions such that the rod-like pushers are capable of reciprocating in their longitudinal directions (i.e., in the radial direction of the hearth) and are arranged radially from a central portion of the hearth. When the pushers advance toward the opening formed in the central portion of the hearth, the pushers operate to push out the raw material to the opening, and this pushing out of the pushers acts effectively with respect to the raw material in regions each having a circumferentially fixed width. Namely, the effective regions having the aforementioned widths are present at a plurality of circumferential positions above the hearth, while the ineffective regions where the pushers exhibit no effect during their operation and the raw material does not move much are respectively formed between adjacent ones of the effective regions. These ineffective regions expand larger on the outer peripheral side as compared to the inner peripheral side of the hearth.
In the effective regions, the raw material moves effectively toward the drop port, and is replaced by new raw material which is consecutively supplied from the raw-material supplying pipes disposed in the effective regions. In contrast, since the exhaust pipes are located in the ineffective regions, the high-temperature gas from the heating space passes through the material in the ineffective regions and reaches the exhaust pipes, so as to heat the raw material in the ineffective regions which does not move much. Namely, in the effective regions, since the raw material moves despite the fact that the high-temperature gas does not actively flow into these regions, a large difference is produced in the degree of heating as compared with the raw material in the ineffective regions. That is, a difference is produced in the degree of heating depending on whether the raw material is located in the effective regions or the ineffective regions. In addition, since the high-temperature gas passes through the raw material in the ineffective regions which does not move much and is at the high temperature, the high-temperature gas is discharged from the exhaust pipes without having undergone sufficient heat exchange with the raw material, so that the thermal energy is not sufficiently utilized.
SUMMARY OF THE INVENTION
In view of the above-described circumstances, it is an object of the present invention to provide a raw-material heating apparatus which is capable of heating the raw material uniformly in the circumferential direction of the hearth and of improving the heating efficiency.
To attain the above object, in a raw-material heating apparatus in accordance with the present invention, a raw-material supplying pipe and an exhaust pipe are disposed in a peripheral portion of a furnace cover, and a heating space is formed by the furnace cover, a peripheral wall, and a hearth. A raw material which is supplied from the raw-material supplying pipe and deposited on the hearth is heated by a heating gas which flows into the heating space. In addition, a pusher for pushing out the raw material on the hearth toward a drop port formed in a central portion of the hearth is supported by the peripheral wall in such a manner as to be capable of reciprocating in a radial direction of the hearth. The raw material pushed out by the reciprocating motion of the pusher is caused to drop through the drop port.
In the present invention, the above-described raw-material heating apparatus is characterized in that lower-end openings of the raw-material supplying pipe and the exhaust pipe, when viewed in an axial direction of the apparatus, are disposed at a same position or at positions close to each other in an effective region for pushing out the raw material by the pusher.
In such a raw-material heating apparatus, the heating gas which is led from the heating space to the exhaust pipe after passing through the raw material on the hearth passes through the effective region where pushing out of the raw material by the pusher is effected ac
Chisaki Co., Ltd.
Hoang Tu Ba
Kanesaka & Takeuchi
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