Note: Descriptions are shown in the official language in which they were submitted.
CA 02440169 2003-09-09
COOLING PLATE
The invention concerns a cooling plate far refractory-lined
shaft furnaces, especially blast furnaces, with a first rolled
cooling plate element facing the inside of the furnace and a
second rolled cooling plate element facing to the rear, which are
welded together, with a cooling channel formed between the first
and the second elements of the cooling plate, and with pipe
sections connected to the coolant inlet and coolant outlet. Both
the first and second cooling plate elements consist of copper or
a low-alloy copper. In addition, the invention concerns a
cooling system.
A cooling plate of this general type is described in German
Patent Application 100 00 987.5, which discloses a cooling plate
for refractory-lined shaft furnaces with cooling channels into
which coolant can be admitted, in which (cooling plate) at least
the front side facing the inside of the furnace consists of a
bloom that contains grooves for receiving refractory material and
is preferably made of copper or a low-alloy copper; in which two
__ _ __ ___. _~__
CA 02440169 2003-09-09
r .
trough-shaped rolled sections, each with the trough facing to the
outside, are welded together; in which bores for receiving the
ends of pipe connection fittings, which are welded in, are
produced in the rolled section or supplementary section on the
rear side; and in which the free ends of the rolled sections are
sealed by caps.
The bending of the first cooling plate element or shield and
the production of grooves in the bent shield is difficult from
the standpoint of manufacturing engineering. Moreover, the more
or less "lens-shaped " cross section of the cooling channel
resulting from the trough-like shape of the two cooling plate
elements has been found to be unfavorable from the standpoint of
fluid mechanics. While the amount of heat flowing from the
lateral fins of the shield towards the cooling water channel is
the greatest, it is precisely in the corners of the "lens " that
the flow rate of the cooling water is the lowest. The low flow
rate leads to a low heat-transfer coefficient oc from the inner
surface of the cooling channel to the cooling water. In
addition, the volume of water flowing past there may experience
an unacceptably high degree of heating.
Therefore, the objective of the invention is to develop a
2
_ _ __ _ ___ T
CA 02440169 2003-09-09
cooling plate of the general type described above with improved
characteristics from the standpoint of manufacturing engineering,
fluid mechanics and cooling engineering.
This objective is achieved by a cooling plate with the
features of Claim 1 and by a system with the features of Claim
12. Advantageous modifications are described in the dependent
claims.
In accordance with the essential concept of the invention,
the first cooling plate element or the shield of the cooling
plate or stavelet is no longer designed as an arched structure,
but rather is designed as a bloom with a plane front side facing
the inside of the furnace, i.e., with a plane hot side, and the
cross-sectional area of the cooling channel formed between the
first and second cooling plate elements is larger in the end
regions than in the center region, as viewed along the
longitudinal extent of the cross-sectional area. The end regions
of the cooling channel cross section are the regions near the
joint lines ox weld seam of the two cooling plate elements. The
end regions may have any desired shape, as long as they have a
larger cross-sectional area than the center region. The effect
of the cross-sectional shape in accordance with the invention is
3
CA 02440169 2003-09-09
that the greatest volume of the cooling water no longer flows in
the center region, but rather in the thermally stressed end
regions of the cooling channel, which results in greater flow
rates and thus more favorable values of the heat-transfer
coefficient. In this regard, the cross section in the center
region should be designed in proportion to the cross section in
the end regions in such a way that the smaller amounts of heat
that develop there can be efficiently eliminated.
All together, a cooling plate with improved flow
characteristics of the cooling water and thus improved cooling
characteristics is created in this way. The temperature on the
hot side, i.e., the side facing the inside of the furnace,
becomes more uniform. Furthermore, a significant advantage is
gained with respect to manufacturing engineering, because the
first cooling plate element now has a plane design and no longer
needs to be curved. In addition, it is much easier to produce
grooves in a plane cooling plate than in a curved cooling plate,
e.g., by milling or roll forming.
In accordance with an especially preferred embodiment, the
end regions of the cooling channel cross section bulge out on one
or both sides. Taking the center region into consideration as
4
CA 02440169 2003-09-09
well, this results in a cooling channel cross section that is
shaped something like a bone or like a half-bone cut along its
longitudinal axis. This shape results in an especially good
ratio of the flow rate of the cooling water to the heat loads
that arise.
To obtain a cooling channel with this type of bone-like
shape, various design combinations are proposed. For a cross
section that is shaped more or less like a half-bone, either a
first cooling plate element with recesses produced in its rear
side facing the water is used, or a second cooling plate element
with a double trough-like shape that bulges out towards the wall
of the furnace is used. A first cooling plate element of this
type is combined with a more or less plane second cooling plate
element; a trough-shaped second cooling plate element is combined
with a first cooling plate element with a plane rear side facing
the water. To obtain a bone-shaped cross section, a first
cooling plate element with recesses is combined with a
corresponding second cooling plate element with recesses or with
a double trough-shaped second cooling plate element.
The recesses, which preferably run parallel to the
longitudinal axis of the cooling plate, are produced by roll
_ __ -!_ _ __~_.. _ _ _
CA 02440169 2003-09-09
forming or by milling. The trough-shaped second cooling plate
element, which is designed thinner than the first cooling plate
element, is produced by roll forming or bending.
Both the first and the second cooling plate element are made
of copper or a copper alloy.
In accordance with a preferred embodiment, the trough-shaped
second cooling plate element has variable material thickness
across its width. It is formed thicker at its edges than in its
center region. This has the advantage that, in the region of
greater heat flow, i.e., in the edge region, more copper material
is available for the conduction of heat. Due to the reinforced
edge regions, the weld for joining the two elements with each
other can also be made more massive. This contributes to the
mechanical stability of the cooling plate and thus to further
improvement of the cooling characteristics of the system.
A second cooling plate element can be welded with the edges
of the first cooling plate element; in accordance with a
preferred embodiment, it is welded to the rear side of the first
cooling plate element as a supplementary section with its
longitudinal edges bent towards the rear side of the first
cooling plate element. To prevent waviness of the edges of the
6
_ ___- _. T ._ _ _.
CA 02440169 2003-09-09
first cooling plate element due to a nonuniform temperature
distribution, it is proposed that slits be produced at regular
intervals in the edge regions of the first cooling plate element
perpendicularly to the longitudinal axis of the cooling plate.
In a preferred embodiment, the free ends of the two joined
cooling plate elements are sealed with caps, and the pipe
sections for the coolant intake and discharge extend through
bores in the second cooling plate element on the rear side. To
reduce pressure losses on the water side in the vicinity of the
coolant inlet and outlet, the first cooling plate element, which
is provided with cooling channel recesses, is hollowed out at the
level of the pipe sections, e.g., by milling out the copper. A
ramp-like transition from the inlet and outlet regions that have
been enlarged in this way to the cooling channel recesses is
produced by gradually reducing the depth of the hollow in the
direction of the cooling channel recesses. The reason for the
smaller pressure losses is the smoother transition that now
exists from the round pipe section to the cooling channel cross
section of the invention with its larger end regions and smaller
center region.
Aside from a flange-and-bracket connection for mounting the
7
CA 02440169 2003-09-09
cooling plate on the furnace wall of the shaft furnace, it is
proposed that the cooling plate have at least two suspension
points, such that a ffirst suspension point is designed as a fixed
connection in the upper part of the cooling plate, preferably
above the pipe section to the coolant inlet or outlet, and a
second suspension point is designed as a loose connection in the
lower part of the cooling plate, preferably just above the pipe
section to the coolant inlet or outlet. This advantageous
suspension with loose attachment points, which are preferably
designed as hangers, allows the lower part of the cooling plate
to undergo thermal expansion.
Further details and advantages of the invention are evident
from the dependent claims and from the following description, in
which the embodiments of the invention illustrated in the
drawings are explained in greater detail. In this regard,
besides the combinations of features enumerated above, features
on their own or in different combinations are also intrinsic
parts of the invention.
Figure 1 shows a cross section of a cooling plate in
accordance with a first embodiment.
Figure 2 shows a cross section of a cooling plate in
8
_-_ _.r ___
CA 02440169 2003-09-09
accordance with a second embodiment.
Figure 3 shows a preferred design of a second cooling plate
element in accordance with Figure 2.
Figure 4 shows a longitudinal section of a cooling plate
mounted on the wall of a shaft furnace.
Figure 5 shows a partial segment of a longitudinal section
of a preferred design of a first cooling plate element in
accordance with Figure 1.
Figure 6 shows a side view of a cooling plate with a
preferred design of the first cooling plate element.
Figure 7 shows a segment of a cooling system mounted on a
furnace wall.
Figure 8 shows the longitudinal section A-A of a cooling
plate in accordance with Figure 7.
Figure 9 shows an enlarged view of the upper partial segment
shown in Figure 8.
Figure 10 shows enlarged views of the partial segments shown
in Figure 8.
Figure 1 shows a cooling plate 1 or stavelet with a first
cooling plate element 2 facing the inside Oi of the furnace and a
second, rear cooling plate element 3, which are welded together.
9
CA 02440169 2003-09-09
The weld seams 4 are located on the protected, cold side of the
cooling plate or stavelet. Between the rear, water side 5 of the
first cooling plate element 5, which is designed as a rolled
copper bloom, and the water side 6 of the second cooling plate
element 3, a cooling channel 7 is formed, which is supplied with
a coolant, preferably cooling water. Pipe sections 8, 9 for
water intake and discharge are mounted in bores in the second
cooling plate element 3. The cooling plate 1 is mounted on the
furnace wall 10, for example, by means of a flange 11, which is
inserted into a bracket 12 mounted on the furnace wall and
secured by a bolt 13 (see Figure 4). The first cooling plate
element 2 is designed as a massive bloom with a plane -- in the
sense of being noncurved -- front side 14, in which grooves 15
are produced, which run transversely to the longitudinal axis of
the cooling plate 1 and facilitate the application of refractory
ramming mix or injection molding compound after completion of the
mounting.
Two recesses 16, 17 that run parallel to the longitudinal
axis of the cooling plate 1 at some distance from each other are
produced on the rear, water side 5 of the first cooling plate
element 2 or shield. Each of these recesses has a more or less
CA 02440169 2003-09-09
semicircular cross section. The cooling channel 7 is sealed on
the rear side, i.e., towards the furnace wall, with an
approximately plane or slightly outwardly curved second cooling
plate element 3 as a supplementary element. This results in the
formation of a cooling channel 7 with a cross-sectional area,
such that the end regions 18, 19, as viewed along the
longitudinal extent of the cross-sectional area (x-direction),
have a larger cross-sectional area than the center region 20.
Figure 2 shows another preferred embodiment of a cooling
plate 101 with a cooling channel cross section claimed in
accordance with the invention. In this embodiment, the desired
cross section of the channel 107 -- here the cross section
perpendicular to the longitudinal axis of the cooling plate -- is
determined by the shape of the second cooling plate element 103,
which is shaped to form a double trough. The desired cooling
channel cross section with larger end regions 118, 119 relative
to the center region 120 of the cross section is created by the
curvature of the troughs 121, 122 and the formation of a center
region 123, which, in the case shown here, is short, but may also
be longer.
To achieve mechanical stability of a cooling plate 101 of
11
' ~ CA 02440169 2003-09-09
' , , _ , ,
this type, the trough-shaped second cooling plate element 203 or
the copper sheet is reinforced, i.e., made thicker, in its edge
regions 324, 325, as shown in Figure 3. This may be
accomplished, for example, by roll forming.
Figure 4 shows the longitudinal section of a cooling plate 1
in its mounted position on the furnace wall, for example, the
wall of a blast furnace. After the cooling plate has been
secured by the flange-and-bracket principle, the remaining space
between the cooling plate 1 and the furnace wall 10 is filled
with backfill compound 26. The pipe sections 8 and 9 are welded
(27) with the second cooling plate element 3. The free ends of
the cooling channel 7 are sealed by caps 28, 29.
Figure 5 shows another preferred embodiment of the cooling
plate 1 based on the embodiment shown in Figure 1. The massive
first cooling plate element 1 is further hollowed out (hollows
30) in the regions facing the pipe sections 8, 9 for the water
intake and discharge, so that the inlet and outlet regions are
enlarged. This cross-sectional enlargement is gradually adapted
-- in ramp-like fashion -- to the curvature of the cooling
channel recesses 16, 17. This has the positive effect of
reducing the cooling water pressure losses.
12
' CA 02440169 2003-09-09
Due to the fact that the second cooling plate element 3 is
mounted on the rear side of the first cooling plate element 2 in
such a way that the edge regions 2a, b (or fin regions) are not
covered, there is the danger of waviness developing in the first
cooling plate element. This is prevented by producing slits 31
in the edge regions 2a, b transversely to the longitudinal axis
of the cooling plate. These slits extend from the edge 32
approximately as far as the second cooling plate element 3. The
slits allow the edge regions to undergo thermal expansion without
stress when the furnace is charged.
The cooling plates of the invention are combined into a
cooling system. For example, they may be installed immediately
adjacent to one another, and their stability can be supported by
a spring-and-groove principle in the first cooling plate
elements. Alternatively, the edge regions of the first cooling
plate elements can also be installed in overlapping fashion.
Figure 7 shows a segment of this type of cooling system 33,
which comprises several cooling plates 1 or stavelets. Figure 7
also reveals another preferred system for mounting the stavelets
on the furnace wall 10. To this end, each cooling plate 1 or
stavelet has several suspension points 34-39, six each in the
13
' ' CA 02440169 2003-09-09
present case, such that the two upper suspension points 34, 35
are designed as fixed suspension points, and the suspension
points 36-39 located below them are designed as loose attachment
points.
A fixed connection between the cooling plate 1 and the
furnace wall 10 is produced at the fixed points 34, 35 (see
Figure 8 and especially Figure 9) by screwing in a screw 40 from
above. For this purpose, a projection 41 is attached --
preferably by welding -- to the furnace wall 10, and a
corresponding projection 42 is attached on the rear side of the
cooling plate 1 outside the region of the cooling channel. The
projections have aligned bores, through which the screw 40 is
inserted to join the two projections. The loose attachment
points 36-39 have a design comparable to that of a door
suspension, as is shown in detail in Figure 10. For this
purpose, at suitable places on its rear side, the cooling plate
has projections 43, each of which is provided with a bore. Each
of the projections 43 is suspended on a pin 44, which is held by
a projection 45 extending out from the furnace wall. These loose
attachment points 36-39 allow the cooling plate 1 to undergo
thermal expansion in the downward direction. To prevent the
14
' ' CA 02440169 2003-09-09
space required for the expansion on the suspensions or loose
attachment points from being blocked by backfill compound, a
throw-away part 46 made of plastic, preferably Styropor, is
inserted at this site during assembly.
All together, the proposed cooling channel cross section
results in a stavelet with optimum characteristics with respect
to the fluid mechanics and cooling effect. In addition, the
stavelet of the invention has advantages over the previously
known stavelet from the standpoint of manufacturing engineering.
Compared to the previously known Cu staves, large savings of
material and weight are realized with these stavelets due to
their smaller thickness, which, in addition, is accompanied by a
greater useful volume of the furnace region.
