DESCRIPTION
SECONDARY REFINING FACILITY AND SECONDARY REFINING METHOD FOR
MOLTEN STEEL
TECHNICAL FIELD
[OOOl]
The present invention relates to a secondary refining facility and a secondary
refining method that sequentially performs secondary refining of molten steel.
BACKGROUND ART
[0002]
Secondary refining facilities that further subjects molten steel, which have been
refined in a converter, an electric furnace, or the like, to secondary refining such as a
degassing process by use of a vacuum chamber are conventionally wide known. The
vacuum chamber used in this secondary refining has a cylindrical main unit. To a lower
end of the main unit, there is attached an immersion pipe, which draws up molten steel
from a ladle containing the molten steel, and another immersion pipe, which returns the
drawn-up molten steel to the ladle.
[0003]
In the secondary refining by use of the vacuum chamber, for example, a ladle
containing molten steel is transferred below the vacuum chamber by use of a carriage for
carrying a ladle, and the molten steel contained in the ladle is drawn up into the vacuum
chamber, to thereby perform a degassing process. Next, the molten steel, which has been
degassed by the vacuum chamber, is returned to the ladle. The ladle containing the
degassed molten steel is transferred by the carriage for a subsequent step. At the same
time, a new ladle containing unprocessed molten steel is transferred below the vacuum
chamber.
[0004]
In recent years, there is an increase in production quantity of high-grade steels
that require such secondary refining. Therefore, there is a demand for improvement in
efficiency of the secondary refining. As a method of improving the efficiency of the
secondary refining, for example Patent Document 1 proposes installation of two vacuum
chambers, for each of which a track for a carriage is provided therebelow.
[0005]
As proposed in Patent Document 1, a track for a carriage is proposed below each
of the vacuum chambers. While one vacuum chamber is performing secondary refining,
the other vacuum chamber performs an operation for a subsequent refining session such as
a transfer of a ladle by the carriage, or conducts minor repair work on the vacuum
chamber such as removal of slag attached to the immersion pipe. By alternate use of two
vacuum chambers, it is possible to sequentially perform secondary refining.
[0006]
Furthermore, Patent Document 2 proposes arrangement of a plurality of ladles on
a rotary movement apparatus for circular movement. With sequential rotation of the
rotary movement apparatus, a plurality of process devices arranged at optional positions
on the circumference for circular movement of the rotary movement apparatus are used to
perform refining. According to the method of Patent Document 2, it is possible to
sequentially perform secondary refining without providing a plurality of tracks.
CITATION LIST
PATENT DOCUMENT
[0007]
Patent Document 1: Japanese Unexamined Patent Application, First Publication
NO. 2003-105430
Patent Document 2: Japanese Unexamined Patent Application, First Publication
NO. 2005-97680
DISCLOSURE OF INVENTION
PROBLEMS TO BE SOLVED BY THE INVENTION
[OOOS]
In the aforementioned vacuum chamber, time-consuming repair work such as
replacement of an immersion pipe is conducted with predetermined frequency, in addition
to the minor repair work. However, for example in the case of conducting repair work on
one of the vacuum chambers in the secondary refining facility of Patent Document 1 for a
long time, it is not possible to use the vacuum chamber and its corresponding track. This
prevents alternate use of the two vacuum chambers. Therefore, the efficiency of
secondary refining is significantly decreased.
[0009]
Furthermore, also in the method of Patent Document 2, if any of the process
devices on the circumference for circular movement is unusable due to repair work, it is
impossible to perform all the processes necessary for secondary refining on the
circumference for circular movement of the rotary movement apparatus. Therefore, in
this case, it is not possible to continue the secondary refining.
[OO 101
The present invention has been achieved in view of the above circumstances, and
has an object to provide a facility and a method that make it possible to perform secondary
refining with high efficiency even during time-consuming repair work of a vacuum
chamber.
MEANS FOR SOLVING THE PROBLEM
[OO 111
To solve the above problems and achieve the above object, the present inventors
adopt the following.
(1) An aspect of the present invention includes: a first vacuum chamber and a second
vacuum chamber that refine molten steel; a vacuum exhaust device that degasses the
molten steel in the first vacuum chamber and the second vacuum chamber; a first vacuum
chamber-side duct that connects between the first vacuum chamber and the vacuum
exhaust device, and a second vacuum chamber-side duct that connects between the second
vacuum chamber and the vacuum exhaust device; a pair of first ladle and second ladle that
contain the molten steel; a first track which is provided below the first vacuum chamber
and on which the first ladle is transferred; and a second track which is provided below the
second vacuum chamber in parallel with the first track and on which the second ladle is
transferred, wherein, when seen in a planar view, the first vacuum chamber and the second
vacuum chamber are provided side by side in a direction orthogonal to a longitudinal
direction of the first track and the second track, wherein each of the first vacuum chamber
and the second vacuum chamber include a horizontal moving mechanism that respectively
move the first vacuum chamber and the second vacuum chamber in a horizontal manner
along the direction orthogonal to the longitudinal direction of the first track and the second
track when the first vacuum chamber and the second vacuum chamber are seen in a planar
view, among a first process position located above the first track, a second process
position located above the second track, a first waiting position located on a side opposite
to the second process position across the first track, and a second waiting position located
on a side opposite to the first process position across the second track; wherein the first
vacuum chamber-side duct and the second vacuum chamber-side duct are configured to be
dividable at a predetermined position between the first vacuum chamber and the vacuum
exhaust device and at a predetermined position between the second vacuum chamber and
the vacuum exhaust device, wherein couplings configured to be capable of freely coupling
the first vacuum chamber-side duct and the second vacuum chamber-side duct that have
been divided is provided at the predetermined positions in the first vacuum chamber-side
duct and the second vacuum chamber-side duct, and wherein a distance from the first
vacuum chamber to a site of the first vacuum chamber-side duct, which is configured to be
dividable is equal to a distance from the second vacuum chamber to a site of the second
vacuum chamber-side duct at which the second vacuum chamber-side duct is dividable.
[OO 121
(2) In the secondary refining facility for molten steel as described above in (I), one or
more selected from a desulfurization device, a composition adjustment device, a
temperature adjustment device, and a clarification device for the molten steel contained in
the first ladle or the second ladle may be provided above each of the first track and the
second track.
[00 1 31
(3) The secondary refining facility for molten steel as described above in (1) or (2) may
further include: a vacuum exhaust device-side duct which is arranged in a space between
the first vacuum chamber-side duct and the second vacuum chamber-side duct and which
is attached to the vacuum exhaust device; and a coupling duct that couples the first
vacuum chamber-side duct or the second vacuum chamber-side duct to the vacuum
exhaust device -side duct, wherein the coupling duct includes: an inverted-U-shaped duct
main unit with downward-facing openings, a first end portion of which is airtightly
connected to a front end portion of the vacuum exhaust device-side duct and a second end
portion of which is airtightly connected to the front end portion of the first vacuum
chamber-side duct or the second vacuum chamber-side duct that is adjacent to the vacuum
exhaust device-side duct; a horizontally-moving measure that horizontally moves the duct
main unit to a selected connection position between the vacuum exhaust device-side duct
and the first vacuum chamber-side duct or second vacuum chamber-side duct; and a
liftingllowering measure that lifts/lowers the duct main unit in a vertical direction to
spacebring both of the end portions of the duct main unit from/closer to the front end
portions of the first vacuum chamber-side duct or the second vacuum chamber-side duct
and the vacuum exhaust device-side duct.
[00 141
(4) Another aspect of the present invention is a secondary refining method for molten steel
that uses the secondary refining facility for molten steel as described above in any one of
(1) to (3), including: causing one of the first vacuum chamber and the second vacuum
chamber to wait at the first waiting position or the second waiting position; and
performing the secondary refining for molten steel by reciprocally moving the other of the
first vacuum chamber and the second vacuum chamber between the first process position
and the second process position.
EFFECTS OF THE INVENTION
[00 1 51
According to the aspects as described above in (1) to (4), the vacuum chambers
are configured to be movable in the horizontal direction. Therefore, with, for example a
single vacuum chamber being reciprocally moved between above the first track and above
the second track, the process for molten steel can be performed sequentially by the single
vacuum chamber. Therefore, if either one of the vacuum chambers needs repairing, the
other of the vacuum chambers is reciprocally moved between the position above the first
track and the position above the second track, to thereby make it possible to continue
sequential secondary refining of molten steel by use of the other of the vacuum chambers.
As a result, even if time-consuming repair work is conducted on a vacuum chamber, it is
possible to perform secondary refining with high efficiency.
BRIEF DESCRIPTION OF THE DRAWINGS
[00 161
FiG. 1 is a plan view showing a schematic structure of a secondary refining
facility according to an embodiment of the present invention.
FIG. 2 is a side view of the secondary refining facility.
FIG. 3 is an explanation diagram showing a vicinity of a vacuum chamber-side
duct of the secondary refining facility.
FIG. 4 is a vertical cross-sectional view showing a part around a flange portion
of the vacuum chamber-side duct.
FIG. 5 is a time chart showing steps of secondary refining by the secondary
refining facility.
FIG. 6 is a time chart showing steps of secondary refining by the secondary
refining facility.
FIG. 7 is a plan view showing a state where a second vacuum chamber of the
secondary refining facility is moved to a second waiting position.
FIG. 8 is a time chart showing steps of secondary refining by a secondary
refining facility according to another embodiment of the present invention.
FIG. 9 is a time chart showing steps of secondary refining by the secondary
refining facility.
BEST MODE FOR CARRYING OUT THE INVENTION
[OO 171
Hereunder is a description of a secondary refining facility and a secondary
refining method for molten steel according to an embodiment of the present invention.
FIG 1 and FIG. 2 are respectively a plan view and a side view showing a secondary
refining facility 1 of the present embodiment.
[00 1 81
The secondary refining facility 1 includes: a first vacuum chamber 10 and a
second vacuum chamber 11 that performs a degassing process of molten steel; a first
exhaust gas process chamber 12 and a second exhaust gas process chamber 13 that process
the exhaust gas respectively from the first vacuum chamber 10 and the second vacuum
chamber 11; 2 :Iacuum exhaust device 14 that exhausts an atmosphere in the first vacuum
chamber 10 and the second vacuum chamber 11 ; a vacuum exhaust device-side duct 15
that is connected to the vacuum exhaust device 14; a first vacuum chamber-side duct 16
that is connected to the first vacuum chamber 10 and the first exhaust gas process chamber
12; a second vacuum chamber-side duct 17 that is connected to the second vacuum
chamber 11 and the second exhaust gas process chamber 13; and a coupling duct 18 that
mutually couples the vacuum exhaust device-side duct 15 to either of the first vacuum
chamber-side duct 16 and the second vacuum chamber-side duct 17.
Below the lirst vacuum chamber 10 and the second vacuum chamber 11, there are
respectively provided a track 20 as a first track and a track 21 as a second track. When
seen both in a planar view and a side view, the track 20 and the track 21 are provided in
parallel with each other. The first vacuum chamber 10 and the second vacuum chamber
11 are arranged side by side in a direction orthogonal to the direction in which the track 20
and the track 2 1 extend. The fact that the track 20 and the track 2 1 are parallel with each
other does not represent that the tracks 20, 21 are arranged exactly in parallel, but
represents that the track 20 and track 2 1 do not interfere with each other because, for
example, the tracks orthogonally cross each other or for other reasons. On the tracks 20,
21, there are respectively installed a first ladle carriage 24 and a second ladle carriage 25
that respectively transfer a first ladle 22 and a second ladle 23 for containing molten steel.
Liftingllowering mechanisms (not shown in the figure) are installed on the first ladle
carriage 24 and the second ladle carriage 25 on a one-on-one basis. The mechanisms are
capable of liftingllowering the first ladle 22 and the second ladle 23.
[00 191
The first vacuum chamber 10 and the second vacuum chamber 11 are for use in
the secondary refining method called the RH method. Their interior portion is lined with
a refractory material. As shown in FIG. 2, on lower edges of the first vacuum chamber
10 and the second vacuum chamber 1 1, there are respectively provided: suction pipes 1 Oa,
1 la as immersion pipes for drawing up the molten steel contained in the first ladle 22 and
the second ladle 23 into the first vacuum chamber 10 and the second vacuum chamber 11 ;
and exhaust pipes lob, 11 b as immersion pipes for exhausting the molten steel, which has
been degassed in the first vacuum chamber 10 and the second vacuum chamber 11, to the
first ladle 22 and the second ladle 23.
[0020]
The first vacuum chamber 10 and the second vacuum chamber 11 are installed at
the same height. The first exhaust gas process chamber 12 and the second exhaust gas
process chamber 13 are also installed at the same height. Between the first vacuum
chamber 10 and the first exhaust gas process chamber 12 and between the second vacuum
chamber 11 and the second exhaust gas process chamber 13, there are respectively
provided a first vacuum chamber-side duct 16 and a second vacuum chamber-side duct 17
so as to extend in a horizontal direction. The first vacuum chamber-side duct 16 and the
second vacuum chamber-side duct 17 communicate respectively with the first vacuum
chamber 10 and the first exhaust gas process chamber 12 and with the second vacuum
chamber 11 and the second exhaust gas process chamber 13. In addition, the first
vacuum chamber-side duct 16 and the second vacuum chamber-side duct 17 are
respectively provided also in a communicating manner on the side opposite to the first
vacuum chamber 10 and the second vacuum chamber 11 in the first exhaust gas process
chamber 12 and the second exhaust gas process chamber 13. After extending
horizontally in the direction opposite to the first vacuum chamber 10 and the second
vacuum chamber 11 for a predetermined length, the first vacuum chamber-side duct 16
and the second vacuum chamber-side duct 17 extend, for example, in the vertically
upward direction. End portions 16% 17a of the first vacuum chamber-side duct 16 and
the second vacuum chamber-side duct 17 that extend vertically upward are configured to
be at the same height. On the end portions 16a, 17a, there is provided a flange portion
30. The first vacuum chamber-side duct 16 and the second vacuum chamber-side duct 17
are installed at the same height in the vacuum chambers 10, 11, respectively.
[002 11
As shown in FIG. 1, at predetermined locations in the first vacuum chamber-side
duct 16 and the second vacuum chamber-side duct 17 between the first vacuum chamber
10 and the first exham gas process chamber 12 and between the second vacuum chamber
11 and the second exhaust gas process chamber 13, there is provided a pair of couplings
3 1. With the couplings 3 1, the first vacuum chamber-side duct 16 and the second
vacuum chamber-side duct 17 are each configured to be dividable into two the first
vacuum chamber-side duct 16 and the second vacuum chamber-side duct 17 are
configured to be joinable each other. The distance X from the first vacuum chamber 10
to the coupling 3 1 provided on the first vacuum chamber-side duct 16, in other words, the
distance from the first vacuum chamber 10 to a site at which the first vacuum
chamber-side duct 16 is dividable, and the distance Y from the second vacuum chamber 11
to the coupling 3 1 provided on the second vacuum chamber-side duct 17, in other words,
the distance from the second vacuum chamber I1 to a site at which the second vacuum
chamber-side duct 17 is dividable, are configured to be equal to each other.
100221
On the sides of the first exhaust gas process chamber 12 and the second exhaust
gas process chamber 13 of each of the divided vacuum chamber-side ducts 16, 17, there
are provided: a retractable duct 32 that is configured to be retractable; and a drive
mechanism 33 that is arranged along an axis direction of the first vacuum chamber-side
duct 16 and the second vacuum chamber-side duct 17 so as to extend across the retractable
duct 32, as shown in, for example, FIG 3. The drive mechanisms 33 are configured to be
extensible along the axis direction of the first vacuum chamber-side duct 16 and the
second vacuum chamber-side duct 17. Thereby, the lengths of the first vacuum
chamber-side duct 16 and the second vacuum chamber-side duct 17 are configured to be
adjustable. The retractable ducts 32 and the drive mechanisms 33 may be provided on
the sides of the first vacuum chamber 10 and the second vacuum chamber 11.
Furthermore, as the retractable duct 32, bellows made of stainless steel or the like, for
example, may be used. As the drive mechanism 33, an air cylinder, an electromotive
actuator, or the like may be used.
[0023]
The first vacuum chamber 10 and the second vacuum chamber 11 as well as the
first exhaust gas process chzmber 12 and the second exhaust gas process chamber 13 are
separated from each other at a predetermined distance. The vacuum exhaust device-side
duct 15 is arranged at the center of the space between the first vacuum chamber 10 and the
second vacuum chamber 11, as shown in, for example, FIG. 2. An end portion 15a of the
vacuum exhaust device-side duct 15, which is on the side opposite to the vacuum exhaust
device 14, extends upwardly at a point on the line connecting the points at which the first
vacuum chamber-side duct 16 and the second vacuum chamber-side duct 17 extend
upwardly. When seen in a planar view, the upwardly-extending end portion 15a is
arranged on a line connecting the end portions 16a, 17a of the first vacuum chamber-side
duct 16 and the second vacuum chamber-side duct 17 so that the distance between the end
portion 15a and the end portion 16a is equal to the distsnce between the end portion 15a
and the end portion 17a. Furthermore, when seen in a side view, the end portion 15a is
arranged at the same height as those of the end portions 16a, 17a of the first vacuum
chamber-side duct 16 and the second vacuum chamber-side duct 17. Therefore, the end
portions 15a, 16a, and 17a are arranged in a horizontal, straight line.
100241
As shown in FIG 2, the first vacuum chamber 10 and the second vacuum
chamber 11 each include a horizontal moving mechanism 40. The horizontal moving
mechanisms 40 horizontally move the first vacuum chamber 10 and the second vacuum
chamber 11, respectively, in a direction orthogonal to the direction in which the tracks 20,
21 extend when seen in a planar view (in an X direction in FIG. 1) while holding the first
vacuum chamber 10 and the second vacuum chamber 11.
[0025]
The horizontal moving mechanism 40 includes: a pair of rails 50 extending along
the direction orthogonal to the direction in which the tracks 20,21 extend when seen in a
planar view; and a carriage 5 1 movable on upper surfaces of the pair of rails 50. Here,
being orthogonal to the direction in which the tracks 20,21 extend does not represent
forming exactly a right angle, but represents that, for example, the tracks 20,2 1 and the
rails 50 cross each other when seen in a planar view. As shown in FIG 1, the pair of rails
50 is provided so as to sandwich the first vacuum chamber 10 and the second vacuum
chamber 11. The rails 50 are provided commonly for both of the first vacuum chamber
10 and the second vacuum chamber 11 while the carriages 5 1 are provided individually for
the first vacuum chamber 10 and the second vacuum chamber 11. Therefore, for
example, firstly by use of the drive mechanism 33, the retractable duct 32 is retracted to
divide the couplings 3 1, and then the first vacuum chamber 10 together with the first
vacuum chamber-side duct 16 divided by the couplings 3 1 is moved on the rails 50 by the
carriage 5 1. Thereby, the position of the first vacuum chamber 10 can be freely changed
among: a first process position P1 and a second process position P2, which are positions
where the track 20 and the track 21 cross the rails 50 respectively above the track 20 and
the track 2 1 and at which secondary refining of the molten steel in the first ladle 22 and
the second ladle 23 is performed; a first waiting position R1 located on the side opposite
to the second process position P2 across the track 20; and a second waiting position R2
located on the side opposite to the first process position P1 across the track 21. Similarly
to the case of the first vacuum chamber 10, firstly by use of the drive mechanism 33, the
retractable duct 32 is retracted to divide the couplings 3 1, and then the second vacuum
chamber 11 together with the second vacuum chamber-side duct 17 is moved on the rails
50 by the carriage 5 1. Thereby, the position of the second vacuum chamber 11 can be
freely changed among the first process position PI, the second process position P2, the
first waiting position R1, and the second waiting position R2. The horizontal moving
mechanisms 40 allow the first vacuum chamber 10 and the second vacuum chamber 11 to
be freely positioned from the first waiting position R1 to the waiting position R2.
However, for example, in the case where the second vacuum chamber 11 is positioned at
the second waiting position R2, the first vacuum chamber 10 is not moved to the second
waiting position R2. Therefore, in reality, the first vacuum chamber 10 is moved from
the first waiting position R1 to the second process position P2, and the second vacuum
chamber 11 is moved from the second waiting position R2 to the first process position PI.
Furthermore, for example, so long as ones capable of being attachedldetached to/from
each other by moving the first vacuum chamber 10 and the second vacuum chamber 11 in
the direction in which the rails 50 extcnd are used as the couplings 3 1, the retractable
ducts 32 and the drive mechanisms 33 need not necessarily be provided. If only the
horizontal moving mechanisms 40 are provided, it is possible to change the positions of
the first vacuum chamber 10 and the second vacuum chamber 11.
[0026]
In a state where the first vacuum chamber 10 and the second vacuum chamber 11
are positioned respectively at the first process position P1 and the second process position
P2, the ducts 16, 17 divided by the couplings 3 1 are configured to be coupled respectively
to the ducts of the first exhaust gas process chamber 12 and the second exhaust gas
process chamber 13. Therefore, for example, in a state where the first vacuum chamber
10 is positioned at the second process position P2, the first vacilum chamber-side duct 16
connected to the first vacuum chamber 10 is in connection with the second vacuum
chamber-side duct 17 via the couplings 3 1. As a result, even if the first vacuum chamber
10 and the second vacuum chamber 11 are positioned at either of the first process position
P1 and the second process position P2, it is possible to perform a degassing process of the
contents of the first vacuum chamber 10 and the second vacuum chamber 11 by the
vacuum exhaust device 14.
[0027]
As shown in FIG. 2, the coupling duct 18 includes: an inverted-U-shaped duct
main unit 60 whose end portions 18a are formed so as to face downwardly; a duct moving
mechanism 61 that moves the duct main unit 60 in a horizontal direction; and a duct
lifting/lowering mechanism 62 that lifts/lowers the duct main unit 60 in a vertical
direction. The distance between the end portions 1 8a, 18a of the duct main unit 60 is
equal to that between the end portion 15a and the end portion 16a. In addition, the
diameter of the end portion 18a of the duct main unit 60 is formed substantially the same
as those of the end portions 1 5a, 1 6a, and 17a. The downward-facing end portion 18a of
the duct main unit 60 is provided with a flange portion 30, similarly to the case of the end
portions 15% 1 6a, and 17a. With the flange portions 30 provided on the end portion 18a
and the end portions 15% 16% and 17a7 coupling surfaces are formed between the end
portion 18a and the end portions 15a, 162, and 17a.
[0028]
The duct moving mechanism 6 1 includes: a pair of rails 63 that extend along the
disposition direction of the end portions 15% 16a, and 17a of the ducts 15, 16, and 17; and
a carriage 64 that is movable on the upper surfaces of the pair of rails 63. The pair of
rails 50 is provided so as to sandwich the end portions 15% 16a7 and 17a of the ducts 15,
16, and 17.
[0029]
On the upper surface of the carriage 64, there is provided a supporting mount 65.
The supporting mount 65 is made of: four pillars 65a that extend from the upper surface of
the carriage 64; and a frame unit 65b fixed to the top portions of the pillars 65a. The
duct liftingllowering mechanism 62 is supported on the frame unit 65b of the supporting
mount 65. As shown in, for example, FIG. 2, the duct liftingllowering mechanism 62 is
configured to be capable of lifiing/lowering the duct main unit 60 by vertically moving the
wires 66 connected to the duct main unit 60 of the coupling duct 18. As the duct
lifting/lowering mechanism 62, for example an electromotive motor that winds and
unwinds the wires 66, or an actuator that is hydraulically or pneumatically driven may be
used.
[0030]
In a state where the end portions 18a of the duct main unit 60 are lifted by the
duct lifting/lowering mechanism 62 above the end portions 15% 16a, and 17a of the ducts
15, 16, and 17, the duct main unit 60 is moved by the carriage 5 1. For example, the duct
main unit 60 is moved so that the end portions 18a are positioned above the end portion
15a and the end portion 16a. Subsequently, the duct main unit 60 is lowered onto the
upper surfaces of the end portion 15a and the end portion 16a. Thereby, with the duct
main unit 60, it is possible to couple the vacuum exhaust device-side duct 15 to the first
vacuum chamber-side duct 16. Similarly, with the duct main unit 60 being lowered onto
the upper surfaces of the end portion 15a and the end portion 17% it is possible to couple
the vacuum exhaust device-side duct 15 to the second vacuum chamber-side duct 17.
Thus, with the switching of the coupling duct 18, the duct to be exhausted by the vacuum
exhaust device 14 is optionally switched to either of the first vacuum chamber-side duct
16 and the second vacuum chamber-side duct 17.
[003 11
On the flange portion 30 provided on each of the end portions 15a, 16a and 17a of
the ducts 15, 16 and 17, and on each of the end portions 18a of the coupling duct 18, there
are provided seal members 70. As shown in FIG 4, the seal member 70 is, for example,
an O-ring with a diameter larger than an inner diameter of each of the ducts 15, 16, 17,
and 18, and is arranged on the coupling surface of each flange portion 30. By the
self-weight of the duct main unit 60 and the negative pressure formed in the duct by the
vacuum exhaust device 14, the seal member 70 is pressed against the flange portion 30
that faces the seal member 70, to thereby keep the coupling surface between the ducts
airtight. The arrangement and number of the seal members 70 are optionally settable,
and are not limited to those of the present embodiment.
[0032]
The secondary refining facility 1 according to the present invention is configured
as described above. Next is a description of an exemplary method of refining molten
steel by use of the secondary refining facility 1. The description is for two cases: where
secondary refining is performed without time-consuming repair work on the first vacuum
chamber 10 and the second vacuum chamber 11; and where secondary refining is
performed in parallel with time-consuming repair work on the first vacuum chamber 10 or
the second vacuum chamber 11. FIG 5 and FIG. 6 are time charts of secondary refining
of molten steel by uses of the secondary refining facility 1. They show the work done at
the first process position P1 and the second process position P2, and the switching work of
the first vacuum chamber 10, the second vacuum chamber 11, and the coupling duct 18 for
the case with and without time-consuming repair work of the first vacuum chamber 10 and
the second vacuum chamber 11, in chronological order.
[0033]
Firstly, at the start of refining of molten steel, for example a first ladle 22 is
transferred to a first process position P1 by the firs: ladle carriage 24 on the track 20 that
corresponds to the first process position P1 (Step S 1 of FIG. 5). At this time, the first
vacuum chamber 10 is positioned at the first process position Ply namely, is in connection
with the first exhaust gas process chamber 12 via the first vacuum chamber-side duct 16.
On the other hand, the second vacuum chamber 11 is positioned at the second waiting
position R2, as shown in, for example, FIG 7. At this time, the coupling duct 18
connects the vacuum exhaust device-side duct 15 and the first vacuum chamber-side duct
16.
[0034]
Subsequently, with the first ladle carriage 24 at rest at the first process position
P1, the first ladle 22 is lifted. Subsequently, secondary refining of molten steel is
performed by the first vacuum chamber 10 (Step S2 of FIG. 5). After completion of the
secondary refining by the first vacuum chamber 10, the first ladle 22 is lowered by the
first ladle carriage 24. After that, the first ladle 22 is moved on the track 20 by the first
ladle carriage 24 for the subsequent step, and at the same time, the first ladle 22 on the
first ladle carriage 24 is replaced (Step S3 of FIG. 5).
[0035]
In parallel with the transfer of the first ladle 22 by the first ladle carriage 24, the
first vacuum chamber 10 is moved from the first process position PI to the second process
position P2 by the horizontal moving mechanism 40 (Step S4 of FIG. 5). At this time,
the first vacuum chamber-side duct 16 connected to the first vacuum chamber 10 is
connected, via the couplings 3 1, to the second vacuum chamber-side duct 17 connected to
the second exhaust gas process chamber 13.
COO361
In parallel with the movement of the first vacuum chamber 10, the duct main unit
60 is moved by the duct moving mechanism 61 of the coupling duct 18. Then, with the
duct main unit 60, the vacuum exhaust device-side duct 15 is connected to the second
vacuum chamber-side duct 17 (Step S5 of FIG. 5). This enables the molten steel to be
processed at the second process position P2 by the first vacuum chamber 10.
[0037]
During the switching of the duct main unit 60 and the first vacuum chamber 10,
the second ladle 23 is transferred to the second process position P2 by the second ladle
carriage 25 on the track 2 1 (Step S6 of FIG 5). After completion of the movement of the
first vacuum chamber 10 and the movement of the coupling duct 18, the second ladle 23 is
lifted by the second ladle carriage 25. Subsequently, secondary refining of the molten
steel in the second ladle 23 is performed by the first vacuum chamber 10 arranged at the
second process position P2 (Step S7 of FIG. 5). After completion of the secondary
refining of the molten steel in the second ladle 23 by the first vacuum chamber 10, the
second ladle 23 is transferred by the second ladle carriage 25 for the subsequent step, and
the second ladle 23 on the second ladle carriage 25 is replaced (Step S8 of FIG 5). At
the same time, switching of the first vacuum chamber 10 and the coupling duct 18 to the
first process position P1 is performed (Step S9 and Step S10 of FIG. 5). Furthermore, in
parallel with the switching of the first vacuum chamber 10 and the coupling duct 18, a
new first ladle 22 is transferred to the first process position P1 by the first ladle carriage 24
(Step Sl1 of FIG 5), and the switching of the first vacuum chamber 10 and the coupling
duct 18 is completed. Then, secondary refining for the first ladle 22 is performed by the
first vacuum chamber 10 (Step S12 of FIG. 5). In the case without time-consuming
repair work on the vacuum chamber 10, the secondary refining of molten steel is
sequentially performed as described above.
[0038]
Next is a description of an exemplary case with time-consuming repair work on
the first vacuum chamber 10. The description is for the case where, due to a defect
caused in for example the first vacuum chamber 10 at the completion of the steps up to
Step S3 of FIG 5, an immersion pipe of the first vacuum chamber 10 is replaced.
[0039]
The steps up to Step S3 of FIG 6 are similar to those of the case shown in FIG. 5.
Therefore, the description therefor is omitted here. Subsequently, in a situation in which
the first vacuum chamber 10 is moved to the second process position P2 in Step S4 in the
case of FIG. 5, if a defect is found in the first vacuum chamber 10 at the time when the
steps up to Step S2 are completed as shown in FIG 6, then the first vacuum chamber 10 is
moved to a first waiting position R1 by the horizontal moving mechanism 40 (Step T1 of
FIG 6). Then, the first vacuum chamber 10 is subjected to repair work at the first
waiting position R1.
[0040]
In parallel with the movement of the first vacuum chamber 10 to the first waiting
position R1, the second vacuum chamber 11 positioned at a second waiting position R2 is
moved to the second process position P2 by the horizontal moving mechanism 40 (Step T2
of FIG. 6). In parallel with the movement of the second vacuum chamber 11 to the
second process position P2, the duct main unit 60 of the coupling duct 18 that connects the
vacuum exhaust device-side duct 15 and the first vacuum chamber-side duct 16 is moved
by the duct moving mechanism 61, to thereby connect the vacuum exhaust device-side
duct 15 and the second vacuum chamber-side duct 17 (Step T3 of FIG. 6). Furthermore,
in parallel with the switching of the coupling duct 18 and the movement of the second
vacuum chamber 11, a second ladle 23 is moved to the second process position P2 by the
second ladle carriage 25 on the track 21 (Step T4 of FIG 6).
[004 11
After that, the second ladle 23 is lifted by the second ladle carriage 25, and then
secondary refining of the molten steel in the second ladle 23 is performed by the second
vacuum chamber 11 (Step T5 of FIG. 6). After completion of the secondary refining of
the molten steel in the second ladle 23 by the second vacuum chamber 11, the second ladle
23 is transferred by the second ladle carriage 25 for the subsequent step, and the second
ladle 23 on the second ladle carriage 25 is replaced (Step T6 of FIG. 6). At the same
time, the second vacuum chamber 11 is moved to the first process position P1 (Step T7 of
FIG 6). Furthermore, the coupling duct 18 is moved by the duct moving mechanism 61
to connect the vacuum exhaust device-side duct 15 and the first vacuum chamber-side
duct 16 (Step T8 of FIG. 6). In parallel with the switching between the second vacuum
chamber 11 and the coupling duct 18, a new first ladle 22 is transferred to the first process
position P1 by the first ladle carriage 24 (Step T9 of FIG 6). After completion of the
switching between the second vacuum chamber 11 and the coupling duct 18, secondary
refining for the first ladle 22 is performed by the second vacuum chamber 11 (Step T10 of
FIG 6). After that, sequential secondary refining of molten steel is continued by the
second vacuum chamber 1 1.
LO0421
According to the embodiment as described above, the first vacuum chamber 10
and the second vacuum chamber are configured to be movable among the first process
position P1, the second process position P2, the first waiting position R1, and the second
waiting position R2. Therefore, with a reciprocal movement of a single vacuum chamber
between the first process position P1 and the second process position P2, for example, it is
possible for the single vacuum chamber to sequentially perform secondary refining of
molten steel. In other words, even if either one of the first vacuum chamber 10 and the
second vacuum chamber 11 is kept waiting at either waiting position, the other of the
vacuum chambers is capable of performing secondary refining of molten steel at both of
the first process position P1 and the second process position P2. Therefore, for example,
even if the first vacuum chamber 10 needs repairing, the first vacuum chamber 10 is
moved to the first waiting position R1, and the second vacuum chamber 11 kept waiting at
the second waiting position R2 is reciprocally moved between the first process position P1
and the second process position P2, to thereby make it possible to continue sequential
secondary refining of molten steel with the second vacuum chamber 11.
100431
In the case of the above-described embodiment as shown in FIG. 5, the second
vacuum chamber 11 is kept waiting at the second waiting position R2. However, for
example, with the first vacuum chamber 10 arranged at the first process position P1 and
the second vacuum chamber 11 arranged at the second process position P2, only switching
of the coupling duct 18 may be performed when secondary refining of molten steel is
sequentially performed. Also in this case, a defective vacuum chamber is moved to a
waiting position, and the other vacuum chamber without a defect is used to perform
secondary refining at the process positions PI, P2 in an alternate manner. Thereby,
secondary refining is sequentially performed. As a result, even if time-consuming repair
work is conducted on a vacuum chamber, it is possible to perform secondary refining with
high efficiency.
[0044]
In the aforementioned embodiment, the description has been only for the process
of molten steel by the first vacuum chamber 10 and the second vacuum chamber 11.
However, in addition to the devices where the degassing process is performed by the
vacuum chamber, the secondary refining facility 1 may further include a device that
performs another secondary refining. Devices that perform another secondary refining
include a desulfurization device, a composition adjustment device, a temperature
adjustment device, and a clarification device. From these, one or more are selected and
installed. As an exemplary case of another secondary refining, the case where as a
desulfurization device, a so-called powder injection device that desulfurizes molten steel,
for example, by adding lime will be described. If a desulfurizing process is performed
along with the degassing process, powder injection devices for performing the
desulfurizing process may be provided. As the powder injection devices, powder
injection lances 80 for supplying a powder of lime may be provided at positions that are
above the tracks 20,21, and are opposite to the first exhaust gas process chamber 12 and
the second exhaust gas process chamber 13 across the first vacuum chamber 10 and the
second vacuum chamber 11, as shown for example with broken lines in FIG 1. The
device for performing secondary refining may be process device such as an LF, a bubbling
process device, and a process device for adding Ca-wires, and the like.
[0045]
FIG 8 is a time chart of the secondary refining chronologically showing:
operations performed on and above the track 20; operations performed on and above the
track 2 1; and switching operations among the first vacuum chamber 10, the second
vacuum chamber 11, and the coupling duct 18, in the case of additionally performing a
desulfurizing process. Hereunder is a description of secondary refining of molten steel
by the secondary refining facility 1 in the case of additionally performing a desulfurizing
process, with reference to FIG 8. In FIG 8, the secondary refining of molten steel is
divided into two processes: a degassing process: and a desulfurizing process.
[0046]
At a start of the refining of molten steel in the case of additionally performing a
desulfurizing process, for example, the first ladle 22 is firstly transferred to be arranged
below a powder injection lance 80 by the first ladle carriage 24 on the track 20 (Step U1 of
FIG 8). Subsequently, a powder of lime is supplied from the powder injection lance 80
to the interior portion of the first ladle 22, to thereby perform a desulfurizing process (Step
U2 of FIG. 8).
[0047]
After completion of the desulfurizing process, the first ladle 22 is moved to the
first process position PI by the first ladle carriage 24 (Step U3 of FIG. 8). At the first
process position PI, a degassing process of molten steel is performed by the first vacuum
chamber 10 (Step U4 of FIG 8). After completion of the degassing process by the first
vacuum chamber 10, the transfer of the first ladle 22 for the subsequent step and the
replacement of the first ladle 22 (Step U5 of FIG 8), the movement of the first vacuum
chamber 10 to the second process position P2 (Step U6 of FIG 8), and the switching of the
coupling duct 18 (Step U7 of FIG 8) are sequentially performed similarly to the case of
steps S3 to S5 shown in FIG. 5.
[0048]
In parallel with the degassing process of molten steel by the first vacuum
chamber 10 at the first process position PI, the second ladle 23 is transferred to be
arranged below a powder injection lance 80 by the second ladle carriage 25 on the track 21
(Step U8 of FIG 8). Subsequently, a desulfurizing process of the molten steel in the
second ladle 23 is preformed by the powder injection lance 80 (Step U9 of FIG 8).
[0049]
After completion of the desulfurizing process of the molten steel in the second
ladle 23, the second ladle 23 is moved to the second process position P2 by the second
ladle carriage 25 (Step U10 of FIG. 8). After completion of the switching between the
first vacuum chamber 10 and the coupling duct 18, a degassing process of the molten steel
by the first vacuum chamber 10 is performed at the second process position P2 (Step Ul1
of FIG. 8). The degassed second ladle 23 is transferred to the subsequent step, and the
second ladle 23 is replaced (Step U16 of FIG. 8).
[OOSO]
After completion of the replacement of the first ladle 22 on the first ladle carriage
24, a new first ladle 22 is transferred by the first ladle carriage 24. The first ladle 22 is
then transferred to be arranged below the powder injection lance 80 (Step U13 of FIG. 8).
After completion of the desulfurizing process on the molten steel in the first ladle 22 (Step
U14 of FIG. 8), the first ladle 22 is transferred to the first process position P1 (Step U15 of
FIG. 8). After completion of the degassing process by the first vacuum chamber 10 at the
second process position P2, the second ladle 23 is replaced (Step U16 of FIG. 8), while, at
the same time, the movement of the first vacuum chamber I0 to the first process position
P1 (Step U17 of FIG. 8) and the switching of the coupling duct 18 (Step U18 of FIG 8) are
performed, and the degassing process on the molten steel in the first ladle 22 is performed
by the first vacuum chamber 10 (Step U19 of FIG 8). A series of these operations are
sequentially performed.
[005 11
As described above, according to the aforementioned embodiment, even if for
example, the powder injection lances 80 are additionally provided for desulfurizing
process of molten steel, it may suffice that, for example, the tracks 20,2 1 are extended so
as to allow the first ladle 22, the second ladle 23, the first ladle carriage 24, and the second
ladle carriage 25 to be moved below the powder injection lances 80. On this point, for
example, in the case where the rotary movement apparatus shown in Patent Document 2 is
used, a required diameter of the circumference for circular movement is determined by the
arrangement of the process devices, the sizes of the ladles, and the like. Therefore, if
equipment is added, it is necessary to enlarge the diameter of the circumference for
circular movement, namely, to enlarge the diameter of the rotary movement apparatus.
However, the building in which the secondary refining facility is arranged is restricted by,
for example, the arrangement of the pillars and the like. Therefore, it is often difficult to
secure the installation site with a predetermined diameter. Especially, the larger the
diameter of the circumference for circular movement is, the more it is difficult to secure a
site without the pillars or the like inside the diameter of the circumference for circular
movement. Contrary to this, according to the aforementioned embodiment, an optional
site without an obstacle such as a pillar may be utilized to extend the tracks 20,21. As a
result, the degree of freedom in the arrangement when a facility is added is made
extremely high.
[0052]
Also in the case of performing a desulfurizing process, only the switching of the
coupling duct 18 may be performed when secondary refining of molten steel is
sequentially performed, with the first vacuum chamber 10 arranged at the first process
position PI and the second vacuum chamber 1 I arranged at the second process position
P2.
[0053]
In the aforementioned embodiment, the powder injection lances 80 used for a
desulfurizing process are provided on the tracks 20,2 1 on a one-on-one basis. However,
as shown in FIG. 8, the desulfurizing process is not performed simultaneously on the track
20 and the track 2 1. Therefore, similarly to the first vacuum chamber 10 and the second
vacuum chamber 11, the powder injection lance 80 may be provided with a horizontal
moving mechanism that moves the powder injection lance 80 in a direction orthogonal to
the tracks 20, 2 1. In this case, it is possible to sequentially perform a desulfurizing
process by use of a single powder injection lance 80. Therefore, it is possible to decrease
the cost of equipment.
[0054]
In FIG. 8, the description has been for the case where the molten steel in the first
ladle 22 and the second ladle 23 is subjected to a single degassing process respectively by
the first vacuum chamber 10 and the second vacuum chamber 11 and is also subjected to a
single desulfurizing process by the powder injection lance 80. However, as shown in, for
example, FIG 9, the desulfurizing process may be performed twice, namely, before and
after the degassing process by the first vacuum chamber 10 and the second vacuum
chamber 11. The time chart of FIG 9 shows an exemplary case where a single powder
injection lance 80, which is provided with the aforementioned horizontal moving
mechanism, is used for both of the first ladle 22 and the second ladle 23 transferred
respectively on the track 20 and the track 21.
[0055]
The case where a desulfurizing process is performed twice on the molten steel in
the first ladle 22 and the second ladle 23 will be described with reference to FIG. 9.
Here, the steps up to Step U4 shown in FIG 9 are similar to those up to Step U4 shown in
FIG. 8, and hence, will not be repetitiously explained. In an embodiment shown in FIG.
9, after completion of the desulfurizing process in Step U2, an operation of moving the
powder injection lance 80 from above the track 20 to above the track 21 is added (Step V1
of FIG. 9).
[0056]
After completion of the operation of moving the powder injection lance 80 in
Step V1, the second ladle 23 is transferred below the powder injection lance 80, which has
been moved by the second ladle carriage 25 on the track 2 1 (Step V2 of FIG 9). Then, a
powder of lime is supplied from the powder injection lance 80, to thereby perform a
desulfurizing process of the molten steel contained in the second ladle 23 (Step V3 of FIG.
9).
[0057]
After completion of the desulfurizing process for the second ladle 23, the powder
injection lance 80 is moved above the track 20 again (Step V4 of FIG 9), and at the same
time, the second ladle 23 is moved to the second process position P2 by the second ladle
carriage 25 (Step V5 of FIG. 9). In parallel with this, after completion of the process of
the molten steel contained in the first ladle 22 by the first vacuum chamber 10 at the first
process position P 1, the movement of the first vacuum chamber 10 to the second process
position P2 (Step V6 of FIG 9) and the switching of the coupling duct 18 (Step V7 of FIG.
9) are performed, and at the same time, the first ladle 22 is moved below the powder
injection lance 80, which has been moved above the track 20, by the first ladle carriage 24
(Step V8 of FIG 9). Then, a second desulfurizing process is performed on the molten
steel contained in the first ladle 22 that has moved below the powder injection lance 80
(Step V9 of FIG 9). The first ladle 22 subjected to the desulfurizing process is
transferred by the first ladle carriage 24 for the subsequent step, and the first ladle 22 on
the first ladle carriage 24 is replaced (Step V 10 of FIG 9). When the first ladle 22 on the
first ladle carriage 24 is replaced and a new first ladle 22 is transferred below the powder
injection lance 80 (Step V1 I of FIG 9), a desulfurizing process is performed on the molten
steel in this first ladle 22 (Step V12 of FIG. 9). After completion of the desulfurizing
process, the powder injection lance 80 is moved above the track 21 (Step V13 of FIG. 9),
and at the same time, the first ladle 22 is moved to the first process position PI by the first
ladle carriage 24 (Step V14 of FIG. 9).
[0058]
After completion of the movement of the first vacuum chamber 10 to the second
process position P2 and the switching of the coupling duct 18, a degassing process of the
molten steel contained in the second ladle 23 is performed at the second process position
P2 (Step V15 of FIG 9). After completion of the process of the molten steel by the first
vacuum chamber 10, the movement of the first vacuum chamber 10 to the first process
position P1 and the switching of the coupling duct 18 are performed, and at the same time,
the second ladle 23 is transferred below the powder injection lance 80, which has been
moved above the track 21, by the second ladle carriage 25 (Step V20 of FIG 9). Then, a
second desulfurizing process is performed on the molten steel contained in the second
ladle 23 (Step V21 of FIG 9). The second ladle 23 subjected to the second desulfurizing
process is transferred by the second ladle carriage 25 for the subsequent step, and the
second ladle 23 is replaced (Step V16 of FIG 9). AAer completion of the movement of
the first vacuum chamber I0 to the first process position P1 (Step V17 of FIG. 9) and the
switching of the coupling duct 18 (Step V18 of FIG 9), a degassing process is performed
on the molten steel in the first ladle 22 by the first vacuum chamber 10 at the first process
position P 1 (Step V19 of FIG 9). With the repetition of these steps, secondary refining
of molten steel is sequentially performed.
100591
Also in this case, the first vacuum chamber 10 and the second vacuum chamber
11 are made movable by the horizontal moving mechanisms 40, to thereby make it
possible to sequentially perform secondary refining of molten steel by a single vacuum
chamber. Therefore, even if for example the vacuum chamber 10 needs repairing, the
second vacuum chamber 11 kept waiting at the second waiting position R2 is reciprocally
moved between the first process position and the second process position, to thereby make
it possible to continue sequential secondary refining of molten steel with the second
vacuum chamber 11. In the aforementioned embodiment, the description has been for
the case of installing a desulfurization device that performs a desulfurizing process after a
degassing process. However, in addition to the desulhrization device, one or more of a
composition adjustment device, a temperature adjustment device, and a molten steel
clarification device may be selected and installed. Alternatively, instead of the
desulfurization device, one or more of a composition adjustment device, a temperature
adjustment device, and a molten steel clarification device may be selected and installed.
Furthermore, in arranging the devices, the arrangement may be optionally determined in
consideration of the arrangement of the equipment and the like around the secondary
refining facility 1.
INDUSTRIAL APPLICABILITY
[0060]
According to the present invention, in using two vacuum chambers to perform
secondary refining of molten steel, it is possible to perform secondary refining also at the
time of time-consuming repair work on a vacuum chamber.
DESCRIPTION OF THE REFERENCE SYMBOLS
1006 11
1 : secondary refining facility
10: first vacuum chamber
11 : second vacuum chamber
12: first exhaust gas process chamber
13: second exhaust gas process chamber
14: vacuum exhaust device
15: vacuum exhaust chamber-side duct
16: first vacuum chamber-side duct
17: second vacuum chamber-side duct
18: coupling duct
20: first track
2 1 : second track
22: first ladle
23: second ladle
24: first ladle carriage
25: second ladle carriage
30: flange portion
3 1 : coupling
32: retractable duct
33: drive mechanism
40: horizontal moving mechanism
50: rail
5 1 : carriage
60: duct main unit
61 : duct moving mechanism
62: duct lifting/lowering mechanism
63: rail
64: carriage
65: supporting mount
66: wire
70: seal member
80: powder injection lance
P 1 : first process position
P2: second process position
R1: first waiting position
R2: second waiting position

CLAIMS
1. A secondary refining facility for molten steel, comprising:
a first vacuum chamber and a second vacuum chamber that refine molten steel;
a vacuum exhaust device that degasses the molten steel in the first vacuum
chamber and the second vacuum chamber;
a first vacuum chamber-side duct that connects between the first vacuum chamber
and the vacuum exhaust device, and a second vacuum chamber-side duct that connects
between the second vacuum chamber and the vacuum exhaust device;
a pair of first ladle and second ladle that contain the molten steel;
a first track which is provided below the first vacuum chamber and on which the
first ladle is transferred: and
a second track which is provided below the second vacuum chamber in parallel
with the first track and on which the second ladle is transferred,
wherein, when seen in a planar view, the first vacuum chamber and the second
vacuum chamber are provided side by side in a direction orthogonal to a longitudinal
direction of the first track and the second track,
wherein each of the first vacuum chamber and the second vacuum chamber
comprise a horizontal moving mechanism that respectively move the first vacuum
chamber and the second vacuum chamber in a horizontal manner along the direction
orthogonal to the longitudinal direction of the first track and the second track when the
first vacuum chamber and the second vacuum chamber are seen in a planar view, among a
first process position located above the first track, a second process position located above
the second track, a first waiting position located on a side opposite to the second process
position across the first track, and a second waiting position located on a side opposite to
the first process position across the second track,
wherein the first vacuum chamber-side duct and the second vacuum chamber-side
duct are configured to be dividable at a predetermined position between the first vacuum
chamber and the vacuum exhaust device and at a predetermined position between the
-. . - a "?
P , > . *: - .*d . . .
29 .-
second vacuum chamber and the vacuum exhaust device,
wherein couplings configured to be capable of freely coupling the first vacuum
chamber-side duct and the second vacuum chamber-side duct that have been divided is
provided at the predetermined positions in the first vacuum chamber-side duct and the
second vacuum chamber-side duct, and
wherein a distance from the first vacuum chamber to a site of the first vacuum
chamber-side duct, which is configured to be dividable, is equal to a distance from the
second vacuum chamber to a site of the second vacuum chamber-side duct at which the
second vacuum chamber-side duct is dividable.
2. The secondary refining facility for molten steel according to claim 1,
wherein one or more selected from a desulfurization device, a composition
adjustment device, a temperature adjustment device, and a clarification device for the
molten steel contained in the first ladle or the second ladle are provided above each of the
first track and the second track.
3. The secondary refining facility for molten steel according to claim 1 or 2, further
comprising:
a vacuum exhaust device-side duct which is arranged in a space between the first
vacuum chamber-side duct and the second vacuum chamber-side duct and which is
attached to the vacuum exhaust device; and
a coupling duct that couples the first vacuum chamber-side duct or the second
vacuum chamber-side duct to the vacuum exhaust device-side duct,
wherein the coupling duct comprises:
an inverted-U-shaped duct main unit with downward-facing openings, a
first end portion of which is airtightly connected to a front end portion of the vacuum
exhaust device-side duct and a second end portion of which is airtightly connected to the
front end portion of the first vacuum chamber-side duct or the second vacuum
chamber-side duct that is adjacent to the vacuum exhaust device-side duct;
, ;. * - e, .-,'"' , -- . - -=e
* -
f
, i d ' - > *.
30
, * > . 'lui3
a horizontally-moving measure that horizontally moves the duct main
unit to a selected connection position between the vacuum exhaust device-side duct, and
the first vacuum chamber-side duct or second vacuum chamber-side duct; and
a liftingllowering measure that lifts/lowers the duct main unit in a
vertical direction to spacebring both of the end portions of the duct main unit fiom/closer
to the front end portions of the first vacuum chamber-side duct or the second vacuum
chamber-side duct and the vacuum exhaust device-side duct.
4. A secondary re-f ining method for molten steel that uses the secondary refining
facility for molten steel according to claim 3, the method comprising:
causing one of the first vacuum chamber and the second vacuum chamber to wait
at the first waiting position or the second waiting position; and
performing the secondary refining for molten steel by reciprocally moving the
other of t h first vacuum chamber and the second vacuum chamber between the first
process position and the second process position.
5. A secondary refining method for molten steel that uses the secondary refining
facility for molten steel according to claim 1 or 2, the method comprising:
causing one of the first vacuum chamber and the second vacuum chamber to wait
at the first waiting position or the second waiting position; and
performing the secondary refining for molten steel by reciprocally moving the
other of the first vacuum chamber and the second vacuum chamber between the first
process position and the second process position. A
-- --
Dated this 28'h day of November, 2013
WHA SRIV AST AV A]
OF REMFRY & SAGAR
ATTO- FOR THE APPLICANT[S]