FURNACE COOLING SYSTEM

SYSTEME DE REFROIDISSEMENT SUR FOUR

English Abstract

FURNACE COOLING SYSTEM
ABSTRACT OF THE DISCLOSURE
A furnace cooling wall construction including
a cooling plate built into the wall disposed trans-
versely with one or more heat pipes enclosed in the
plate and extending between a cooling chamber in the
plate and adjacent the inner end of the plate with
cooling water circulated to the chamber for circula-
tion by the heat pipe.

Claims

WHAT IS CLAIMED IS:
1. In a furnace wall construction having at
least one cooling plate built into the wall, said
plate being disposed transversely in the wall, at least
one heat pipe enclosed in said plate extending toward
the interior of the furnace, the wall of the furnace
being built up in layers and said cooling plate dis-
posed at intervals between the layers, said cooling
plate being tapered toward its edge facing the interior
of the furnace, said plate being at least partially
hollow, an inlet adjacent the rearwardly facing edge
of the plate to receive a flow of cooling water into
said hollow, said rearwardly facing edge comprising
a back plate welded to the plate to enclose the hollow
and form a cooling chamber through which the cooling
water is circulated, said back plate including an.
inlet and an outlet for the circulation of said cooling
water connected with cooling chambers of other plates, .
said cooling plate including a solid portion extending
from said interior edge to said hollow and having a
plurality of bores extending from adjacent the interior
edge to the hollow, and heat pipes in said bores ex-
tending into the cooling chamber formed by said hollow.
2. A furnace wall construction as in claim
1 wherein sealing rings are provided around said heat
pipes adjacent to the inner ends of said bores to seal
the bores around the heat pipes adjacent to the hollow
cooling chamber.

3. A furnace wall construction as in claim
2 wherein said cooling plate is fabricated from copper.
4. A furnace wall construction as in claim
1 wherein the rearwardly facing edge is comprised of
a back plate removable from the cooling plate by means
of removable bolts.

Description

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F NACE COOLING SYSTEM
BACKGROUND OF THE INVENTION
One of the major inconveniences and sources
of expense in the operation of a shaft furnace is the
need to replace the refractory lining of the furnace
at intervals. By cooling the refractory lining it can
be made to last longer, but the replacement of the
cooling means increases the complexity and expense
of the re-lining operation. One method of cooling
shaft furnaces known as plate cooling has been known
for many years and has generally found favour. This
method involves the provision of water-cooled plates
in the refractory lining of the furnaces, which plates
extend transversely with respect to the working surface
of the lining. These plates are usually built into
the furnace walls as the furnaces lining is built up.
Thistype of cooling is particularly suitable for the
bosh zone of the furnace although it can be used in
other zones. It is usual for about seven to nine
cooling plates to be interconnected by intermediate
water inlet and outlets so that a single main water
inlet and a single main water outlet only need be
provided for this series of plates. This type of
cooling is very efficient whilst it is operative
normally since the cooled face of the plate is close
to the inner face of the lining of the furnace. However,
when leakage occurs, and in mid to late campaigns this is
frequent, then serious water ingress can occur.
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SU~RY OF TI~E INVENTION
This invention relates to the cooling of
furnaces and particularly to cooling apparatus disposed
in the walls of the furnace to conduct heat from the
working surfaces of these walls.
According to the present invention there
is provided a furnace having a cooling system including
at least one heat pipe, one end of which contacts a
eooling fluid and the other end of which extends towards
the interior of the furnaee and is in thermal eontaet
with the lining of the furnaee.
A plurality of heat pipes may be provided
enelosed within a common proteetive easing which casing
is loeated within or adjaeent the furnaee walls.
The cooling system may he a plate type
eooling system in whieh at least one plate is disposed
transversely in the walls of the furnaee and eneloses
at least one heat pipe extending within said plate
towards the interior of the furnaee.
The plate may enelose a ehamber adapted to
reeeive a flow of eooling fluid, the ehamber being
loeated at the end of the eooling plate remote from the
interior of the furnaee.
The ehamber for the eooling fluid may have
a back wall either welded to the remainder of the plate
or seeured by means of bolts to a flange at the rear
of the plate.

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OBJECTS OF THE INVENTION
It is an object of the present invention to
provide an improved cooling system for a shaft furnace.
The system relies on the use of heat pipes.
A heat pipe is a relatively simple structure
that transmits thermal energy very efficiently, it is
a sealed enclosure containing a fluid material and a
wick. One end of the pipe is situated adjacent a heat
source and the other end adjacent a heat sink. The
fluid is so chosen as to be liquid at the sink tem-
perature and in the vapour phase at the heat source
temperature. The vapour diffuses from the hot end
by the capillary action of the wick. Heat pipes are
most often cylindrical in shape, but can be made in
other forms, for example a laminar shape.
DESCRIPTION OF TIIE DRAWINGS
In the drawings:
Figure 1 is a view of a vertical section
through part of the wall of a blast furnace;
Figure 2 is a horizontal section through
a cooling plate;
Figure 3 is a vertical section along the
line X-X of the cooling plate of Figure 2;
Figure 4 is a horizontal section through
an alternative cooling plate; and
Figure 5 is a vertical section along the
line X-Y of the cooling plate of Figure 4.

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DESCRIPTION OF PREFERRED EMBODIMENT
Embodiments of the invention will now be
described, by way of example only, with reference to
the accompanying drawings.
In Figure 1 the part of the furnace shown is
the lower bosh zone and the zone around a tuyere 2.
The walls of the blast furnace are built up in layers
and cooling plates 1 are interposed with these layers
at intervals.
The cooling plates are tapered towards their
inner-facing edges 3 and are partially hollow. The
interiors of the cooling plates 1 receive a flow of
cooling water via inlets 4 at their rearwardly-facing
edges.
Referring to Figures 2 and 3, each plate 1
located in the walls of the furnace is a generally
flat structure having a first portion 5 which is solid
and is the end of the plate which is located closer to
the interior of the furnace. An enclosure-defining
wall 6 extends from the circumference of the rearwardly
facing surface of the portion 5 and defines a chamber 7
for the cooling fluid. A back plate 8 is welded onto
the wall 6 to complete the enclosure of the cooling
chamber 7. The back plate includes inlet and outlet
apertures connecting with the cooling chambers of other
cooling plates. The solid portion 5 of the plate
includes a number of bores 9 extending from its rearward
surface towards its front edge 3. These bores terminate
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before the front edge 3 of the solid portion 5 and are
so dimensioned to receive cylindrical heat pipes 10 so
that when located in the bores 9 the heat pipes 10
extend to a considerable extent out from the portion
5 into the cooling chamber 7. Sealing rings 11 are
provided at the openings of the bores 9 on the rear-
ward facing surface of the portion 5 so that a water
tight seal is maintained around heat pipes 10 when lo-
cated in the bores. The heat pipes can be moved towards
and away from the inner-facing edge 3 of the plate
by moving them within the bores 9 so that some heat
pipes may be positioned further from the hottest sur-
face so that they remain operative even when the hot
ends of the fully inserted heat pipe have been worn
back.
MODIFIED EMBODIMENT
Referring to Figures 4 and 5, in an alterna-
tive arrangement the cooling plate may include a
removable back plate 12 connected to a flange 13
extending from the enclosure wall 6. The connection
may be by means of bolts 14, allowing the back plate 12
to be removed so that the heat pipes may be removed
or their positions in the bores altered.
Each plate in the system may be fabricated
from copper, or alternatively it may be cast in alloy
steel, refractory or a combination of metal and high
conductivity refractory. The heat pipes may be curved
to suit the contour of the cooling plates and may be
partly cast in the solid portions S of the cooling plates.