Note: Descriptions are shown in the official language in which they were submitted.
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PANEL ADAPTED FOR COOLANT TH~OUGH FLOW, AND AN ARTICLE
INCORPORATING SUCH PANELS
This invention relates to a panel adapted for the flow
therethrough of a coolant such as air or water, and to an
article such as an electric arc furnace or cooling tank
incorporating such panels.
Such a panel may be used for instance, to define an
interior wall of a furnace, e.g. an electric arc furnace, as a
replacement, in part, for relatively expensive refractory
material. Alternatively, such a panel could be used as, or
to form part of, a furnace door or roof, but irrespective of
its particular use, the purpose of the furnace panel is to
form a barrier between a hot zone within a furnace and an
ambient cooler zone, with the coolant prolonging the service
life of the panel. Alternatively, the panel may be employed
to cool a liquid or gaseous medium such as hot oil or hot air,
e-g. by immersing the panel in the hot oil etc., or by
constructing an oil tank from a number of such panels.
For furnace use, known panels are generally
rectangular if they are intended to constitute a door or a
portion of a furnace wall, or are segmental if they are to
constitute a portion of the roof of a circular, electrical arc
furnace. However, irrespective of the overall panel shape,
one panel construction currently in use comprises sinuously
arrayed, circular section, water flow tubing extending over
the entire area of the panel. The tubing thus comprises a
plurality of parallel horizontally extending tube portions
closely spaced with respect to one another and welded one
above the other (insofar as a furnace door or wall portion is
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concerned~ between the bottom and top of the panel, with the
horizontal tube portions approximating in length to the width
of the panel, and with 180 return bends at the ends of the
horizontal tube portions. As tube of requisite cross-section
5 and wall thickness is available from manufacturers in finite
lengths <6m, it follows that sinuous tubing of say 40m total
length must incorporate a number of butt joints e.g., 6 to 8
joints (even when using 6m long tubes) between adjacent tube
ends. The butt joints are normally disposed down the centre
10 of the panel, and, and form electric furnace walls the panels
subsequently need to be bent to arcuate shape but such bending
disadvantageously stresses these butt joints which often
results in premature failure or water leakage at these joints.
An inlet pipe is of course required to convey cooling water to
15 an inlet end of the sinuous tubing, and an outlet pipe to
convey water from an outlet end of the sinuous tubing. Apart
from having a disadvantageously short service life, such
furnace panels are expensive to fabricate in that, because of
the use of circular section tubing, specially profiled in-fill
20 pieces must be employed between adjacent external peripheries
of adjacent horizontal tube lengths, with two adjacent
horizontal tube portions welded to opposite edges of a common
in-fill piece, while furthermore, differential expansion and
contraction between horizontal tube portions and in-f ill
25 pieces frequently results in unsatisfactory welds. Equipment
is also required to provide the 180 return bends between one
horizontal tube portion and the adjacent horizontal tube
portion. In addition, the use of circular section tubing
presents an irregular surface to the inside of the furnace,
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and consequently a discontinuous presentation of cooling water
to the inside of the f urnace.
Another furnace panel from practice is a so-called box
panel, being constructed from a back sheet, to an inner face
5 of which are welded fins defining a coolant flow path, with
the panel and flow paths completed by welding a front sheet to
and over the f ins. Such a panel, to form part of a furnace
wall, also needs to be bent to the curvature of the particular
furnace involved, but is prone to relatively short service
10 life, to coolant leakage and to distortion under service
- temperatures.
Another panel construction, known not f rom practice
but from GB 1,558,040, describes the use of rectangular cross-
section water cooling boxes, with each box having an
individual water inlet connection at one end, and water outlet
connection at the other end.
Basic objects of the present invention are to provide
a construction of panel adapted for the flow of coolant
therethrough, which is considerably simpler and hence cheaper
20 to manufacture~ which has a greater rate of heat transf er and
which extended service life, compared with known panels.
According to a first aspect of the present invention,
there is provided a panel, adapted f or the flow of coolant
therethrough, comprising coolant flow tubing having a coolant
25 inlet aperture at an inlet end of the coolant flow tubing and
a coolant outlet aperture at an outlet end of the coolant flow
tubing, the coolant flow tubing comprising a plurality of
elongate tube lengths formed from hollow rectangular section
material, the tube lengths being disposed in parallel
30 relationship, either stacked one on top of the other or side-
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by-side, with adjacent external faces of adjacent top and
bottom walls of adjacent tube lengths abutting one another,
with the end of each tube length closed off, and with coolant
flow apertures communicating between adjacent tube lengths
5 adjacent the ends thereof such that, in use, coolant flows in
at one end of each tube length, along the tube length, and out
at the other end of ~ach tube length, to and through
successive tube lengths of the panel.
Thus, the panel in accordance with the invention, when
compared with the prior art sinuous tubing panel firstly
enables in-fill pieces to be eliminated, resulting in a
greatly simplified and more economical welding operation,
whilst furthermore eliminates butt-joints along the centre of
the panel, whilst in addition the flat nature of the external
walls of the rectangular section tube lengths enables a flat
face, which may be considered as a "hot" face, to be presented
to the inside of e.g., the furnace or oil tank, and hence a
greater area for presentation of coolant to the hot zone and
hence enhanced heat transfer. Compared with the prior art
box panel, the panel of the invention by employing hollow,
rectangular section tube lengths benefits from the inherent
strength of such tube lengths in resisting distortion in
service and hence maintaining integrity of the panel not only
in service, thereby avoiding troublesome coolant leakage
particularly if the coolant is water, but also when being
craned out of a furnace for repair or replacement, when
coherent removal of the panel saves time and avoids danger to
personnel if panel break-up occurs during craning. Finally,
compared with GB 1,558,040, the panel of the invention, by
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incorporating coolant flow apertures between adjacent tube
lengths, so that coolant may flow successively through the
tube lengths, greatly simplifies the overall panel
construction and hence reduces manufacturing, installation and
remval costs, whilst simultaneously and significantly reducing
the possibility of coolant leakage by providing but one
coolant inlet connection and but one coolant outlet
connection.
According to a second aspect of the invention, there
is provided an electric arc furnace incorporating panels in
accordance with the first aspect.
According to a third aspect of the invention, there is
provided a cooling tank incorporating panels in accordance
with the first aspect.
The tube lengths can be produced in carbon steel or,
for maximum life but at greater cost, in stainless steel.
Alternatively, for specific duties copper, or metal alloy may
be employed, but in principle, any material capable of
withstanding the temperatures encountered in service may be
employed. The tube lengths can be either of hollow rolled
box section e.g. 120 x 80 x 10mm or, less satisfactorily,
could be fabricated to rectangular section from plates, and/or
angles and/or channels. As rolled box sections conventionally
have an internal seam, this is preferably arranged to be, in
use, at the "cold" side or face of the panel.
Although the tube lengths could be secured at their
ends to a common support plate extending the full length or
depth of the panel, it is much preferred for the tube lengths
to be secured together along mutually abutting longitudinal
edges. Preferably, such securing is by welding, either
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continuously or by stitch welding. Certainly, continuous
welding ensures adequate panel strength, particularly when
suspended by crane during insertion or removal from a furnace.
Preferably, the panel is provided, at one lateral
side, i~ et tube length extending orthogonally, or generally
so, with respect to the axes of the parallel tube lengths,
which inlet tube length is also secured e.g. by welding, to
the adjacent ends of the parallel tube lengths. If the panel
is considered as located vertically as part of a furnace wall,
the parallel tube lengths would be horizontal and the inlet
tube length would bevertical so that coolant flow isinto the
upper end of the vertical tube length at which location the
cooling water inlet aperture is provided, with the flow of
cooling water being down the vertical tube length and into the
bottom-most parallel tube length, with water flow then being
successively up successive parallel tube lengths until the
uppermost parallel tube length is reached, with water flow out
of the panel being through the outlet aperture which is
provided in the uppermost parallel tube length. A welded
joint - either a mitre joint or a butt joint - would be
required between the lower end of the (vertical) inlet tube
length and the bottom-most parallel tube length. Such a
joint could be avoided if the inlet tube length and bottom-
most parallel length are integral e.g. by forming both from
one length circular section tubing with the joint replaced by
a 90 bend. Preferably, the panel is provided at its rear
"cold" face with a support plate, which is conveniently welded
in position and provided with two spaced-apart and support
members, also preferably welded in position, serving to locate
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or key the panel in its required position e.g., by apertures
in the support members being lowered into engaging pins of the
furnace structure. The panel is also provided with two
coolant conveying pipes, one pipe being connected to the inlet
aperture of the inlet tube length, and the other connected to
the outlet aperture of the uppermost parallel tube length,
respectively ~or conveying ~oolant from a pumping source to
the panel, and heated coolant from the panel, the pipes, for a
furnace panel, being of length such that they will pass
through a steel shell located behind the panel.
For use as wall components of an electric furnace, the
panels e.g., 2 - 3 m high and 2 - 3 m wide may each subtend an
act of 22 30l, so that 16 such panels would be required to
surround an electric furnace. It follows that the horizontal
1s tube lengths need to be bent to a curvature appropriate to
that of the particular electric furnace involved. For use as
a slag door, the panel would not be curved but would be flat.
As a slag door or furnace wall component, the "hot"
face of the panel may be provided with slag catching cups.
These may be shallow, "~n-shaped steel members welded in
position, preferably along the weld line between two adjacent,
parallel tube lengths. Also when a furnace door or wall
portion is involved, the lower part of the panel is subjected
to higher temperatures than the upper part of the panel. It
may be desirable therefore to have differential flow rates
between the upper and lower parts. This could be achieved by
having each part constitute an individual coolant flow
circuit, with a greater flow rate through the lower part than
the upper part. Flow rate variation may be achieved b~ using
two pumps of the differing capacities, or a single pump with a
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restricted flow, such as a smaller diameter inlet pipe, to the
upper part~
For use as part of a furnace roof, the panels would be
segmental in plan, and dished so that all the segmental panels
5 together formed a shallow, conical roof, wbilst the parallel
tube lengths would be arrayed side-by-side in this embodiment.
For use as a ~ooling panel e.g., for hot oil, the
panel may be immersed in an otherwise conventional oil tank,
e.g. a return tank of a hydraulic system. Alternatively, a
return tank may be constructed using one or a multiple number
of panels in accordance with the invention, dependent upon the
rate of heat transfer required. Thus, a rectangular tank
could be constructed using between one and five panels, the
five panel version being four side walls and a tank bottom.
The invention will now be described in greater detail,
by way of examples, with reference to the accompanying
drawing, in which:-
Figure 1 is a plan view of a first embodiment of panel
in accordance with the invention for use as a wall component
of a circular, electric furnace; c~'~
Figure 2 is a view looking on the rear of the panel of
Figure 1 in the direction of arrow A;
Figure 3 is an end elevation of Figure 1 in the
direction of arrow B;
Figure 4 is a plan view of a second embodiment of
panel in accordance with the invention, for use as a slag door
of a furnace;
Figure 5 is view looking o the rear of the panel of
Figure 4 in the direction of arrow C;
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Figure 6 is an end elevation of Figure 4 in the
direction of acrow D;
Figure 7 is a part sectional view through a portion of
Figure 4;
Figure 8 is a sectional side elevation on the line
VIII-VIII of Figure 9 of a panel adapted to form part of a
roof of an electric arc furnace, and
Figure 9 is a plan view of the panel of Figure 8.
In the drawings, like components, are accorded like
reference numerals.
A furnace panel 1 through which water as a coolant is
adapted to flow, comprises coolant flow tubing, including a
plurality of parallel tube lengths 2 each having a length
approximating to the desired width of the panel, the parallel
tube lengths 2 being stacked horizontally one above the other,
to build up the panel 1 to a desired height, the panel 1 being
rectangular with a top edge being defined by an uppermost tube
length designated 2A and a bottom edge of the panel being
defined ~y a lowermost tube length designated 2B, with the
intermediate, parallel tube lengths designated 2. Each tube
length 2, 2A, 2B is conveniently of 120 x 80 x 10mm
rectangular hollow section steel, comprising a top wall 3
located in a horizontal plane, a bottom wall 4 located in a
parallel horizontal plane, a pair of spaced apart, parallel
and vertical side walls 5, being a "hot" sidewall 5 adapted to
face the furnace interior and a "cold" sidewall 6 remote from
the furnace interior. Because of the superposition of the
hot sidewalls 5, there is formed a generally flat and
uninterrupted front face 7 to the panel, for efficient heat
transfer, and similarly a back face 8. Each tube length 2,
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2A, 2B is closed off by an end cap 9 welded in position,
while, as indicated in Figure 3, for convenience of
construction, one end cap8Ais common to a pair of superposed
tube lengths 2, 2A, 2B. Thus, when stacked one on top of the
5 other, the external face of a bottom wall ~ of an upper
parallel tube length 2A or 2 seats on the external face of a
top wall 3 of an immediately lower parallel tube length 2 or
2B. The stacked tube lengths 2, 2A, 2B are secured to one
another along mutually abutting or adjacent longitudinal
edges, by welding at 10 at both the front face 7 and back face
8. The welding 10 is preferably continuous the entire length
of each parallel tube length 2, 2A, 2B, and hence across the
entire width of the panel, for maximum strength, although
stitch welding is possible.
Each parallel tube length 2, has a water inlet
aperture 11 and a water outlet aperture 12, whilst the
uppermost tube length 2A has a water inlet llA and a water
outlet 12A in communication with a water conveying outlet pipe
13, and the lowermost tube length 2B has a water outlet 12B
and a water inlet llB in comunication with a vertically
extending, hollow, rectangular section inlet tube length 1~
provided at one lateral side of the panel 1, corresponding in
length to the height of the panel 1, and being secured by
welding at 15 to adjacent ends/end caps 9, 9A of the tube
lengths 2, 2A, 2B. The vertical tube length 14 is also
provided with a cooling water inlet aperture llC in
communication with a water conveying inlet pipe 16 and a
cooling water outlet aperture 12C in communication with the
inlét aperture llB of the lowermost tube length 2B, with a
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welded butt-~oint 17 between the vertical inlet tube length 14
and the lowermost tube length 2B.
A pair of vertically spaced-apart support plates 18
- having three spaced-apart support ribs 19 project rearwardly
5 of the panel 1, the plates 18 being provided with a pair of
apertures 20 by which the panel 1 is secured in its desired
position by the apertures 20 being f itted onto locating pins
(not shown) of the f urnace structure.
The arrangement of water inlets and outlets in the
various tube lengths 14, 2A, 2 and 2B is such that cooling
water, pumped from a remote source, flows down the vertical
tube length 14 as indicated by arrow 21 and into the lowermost
tube length 2B as indicated by arrow 22. From the lowermost
tube length 2B water passes successively from one tube length
to the next above tube length through the stack, indicated by
arrow 22, with the water flowing in opposite directions,
through the remaining tube lengths 2, and lastly into the
uppermost tube length 2A, water leaving the uppermost tube
length 2A via its outlet aperture 12A and the outlet pipe 13.
As can be appreciated from Figures 1 and 3, the panel
1 is bent to arcuate shape so that it subtends an angle of 22
30' and hence sixteen such panels are reguired 'co define
totally the inside of a circular, electric arc furnace.
The second embodiment of panel lA illustrated i n
Figures 4 - 7, is intended for use as a slag door and is
basically of the same construction as the panel 1 of Figures 1
- 3, but differs in that the panel lA is flat, has a mitre
joint 23 between the vertical inlet tube length 14 and the
lowermost tube length 2B, and at its upper end has two spaced-
apart pair s of apertured lugs 24 each having a hol e 25 to
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receive a hinge pin (not shown), with a support plate 26 for
the lugs 24, the latter and the support plate 26 being welded
to the uppermost tube length 2A and the upper end of the
vertical inlet tube length 14.
In Figures 8 and 9 is indicated a modifled panel lA
for use as part of a furnace roof, which panel is both
segmental, as shown in Figure 9, and curved, as indicated in
Figure 8 so that a plurality of such panels assembled end-to-
end will define a circular roof of an electric arc furnace.
Because of the side-by-side relationship of the panels 2A, 2
and 2B, there is formed a curved and generally uninterrupted
inner face 7A to the panel, and an outer face 8A. As before,
a water inlet pipe is indicated at 16 and a water outlet pipe
at 13, the water flow being along the inlet tube length 14A as
indicated by arrow 21, then from the outer end of the inlet
tube length into the tube length 2B, and then successively
through the parallel tube lengths 2, 2A to the outlet pipe 13.
Panels in accordance with the invention could also be used
.. . . .
in continuous casting plants and in rolling mills or other locations
20 where thermal protection, e.g. of electric motors, is required.
