Shaft furnace

A shaft furnace, e.g. a blast furnace, has a bosh, a shaft and a mantle ring at the transition from the bosh to the shaft. At both the bosh and the shaft, there is a steel jacket and a refractory lining on the inside of the steel jacket. Cooling elements extend into the refractory lining from the steel jacket and are arranged for through-flow of cooling liquid. To provide additional cooling at the critical transition from the bosh to the shaft adjacent the mantle ring, there is at least one transition cooling element located near the mantle ring so as to cool a region of the refractory lining of the bosh adjacent the steel jacket at the transition. The transition cooling element has, as seen in plan view, a T-shape, with the cross-bar of the T-shape extending in the circumferential direction of the furnace.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a shaft furnace having a construction comprising a 
bosh and a shaft (also known as a stack) and a mantle ring (also known as 
a lintel) at the transition from the bosh to the shaft. This construction 
has a steel jacket and a refractory lining on the inside of the jacket. 
Cooling elements arranged for through-flow of liquid extend from the 
jacket into the refractory lining. An example of such a furnace is a blast 
furnace. 
2. Description of the Prior Art 
Such a furnace is known from Dutch patent application NL-A-7312549 (and 
corresponding U.S. Pat. No. 3,953,007). The cooling elements in the 
refractory lining of the furnace serve to extend the service life of the 
refractory lining and in this way to raise the service time of the furnace 
between repairs. Furnaces of the kind described above particularly 
furnaces of a relatively older design, are usually provided with a small 
number of cooling plates of small dimensions. In such furnaces a 
relatively thin jacket suffices. However, the design entails that the heat 
control in the transition zone from bosh to shaft (stack) is not optimum 
and leads to crack formation and leakages. 
SUMMARY OF THE INVENTION 
The object of the invention is now to provide a design for such a furnace 
so that the tendency for occurrence of crack formation and of leakages 
round and in the transition zone of bosh, jacket and mantle is 
counteracted. 
The shaft furnace in accordance with the invention is characterised in that 
at least one transition cooling element is located near the mantle ring so 
as to cool-a region of the refractory lining of the bosh adjacent the 
steel jacket at the transition. The transition cooling element has, as 
seen in plan view, a shape comprising an elongate portion extending 
longitudinally in the circumferential direction of the furnace. For 
constructional reasons, preferably the transition cooling element has a 
T-shape in which the cross-bar of the T constitutes the elongate portion 
and the stem of the T extends outwardly therefrom, i.e. towards the 
furnace jacket. 
This arrangement achieves a very effective cooling in the critical 
transition zone at the mantle ring and bosh, and this cooling has a 
favourable effect on the service life and the durability of the 
construction in this transition zone. 
Preferably there are a plurality of the transition cooling elements 
arranged in a row horizontally spaced apart from each other in the 
circumferential direction of the furnace, and the elongate portions of 
said plurality of transition cooling elements are mutually spaced from 
each other, preferably by a short distance, e.g. less than the 
circumferential length of each element. 
In this way cooling of the wall construction in the vicinity of said 
transition zone can be provided optimally, while the openings to be 
provided in the jacket for the cooling elements can be kept relatively 
small and the consequent weakening of the jacket remains limited. This is 
further enhanced by providing each cooling element with connections for 
supply and discharge of cooling liquid which are accessible on the outer 
side of the jacket and are somewhat at an angle relative to the steel 
jacket. In this connection the invention is particularly well suited to be 
applied in the aforementioned furnaces which are equipped with a 
relatively thin jacket. It is further preferred that the transition 
cooling elements are located in staggered positions relative to the row of 
cooling elements next above them. 
Most suitably, the transition cooling element is above the mantle ring, and 
as seen in plan view, the elongate portion of said transition cooling 
element is at the inner periphery of the mantle ring. 
The invention also consists in the cooling element as described for use in 
a shaft furnace.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Shaft furnaces of the kind described here are generally known in the iron 
and steel industry and need no further explanation. 
In FIG. 1, there is shown an upper part of the zone 1 that constitutes the 
bosh of the shaft furnace, and a lower part of the zone 2 of the shaft of 
the shaft furnace. In the transition zone 3 located between bosh 1 and 
shaft 2, there is a mantle ring 4 in the form of an annular plate which is 
supported by a plurality of columns 5. This type of furnace is known as a 
column oven. It has a steel jacket 9 for the bosh and a steel jacket 9a 
for the shaft, and a refractory lining as shown interiorly of the steel 
jacket 9, 9a. In the refractory lining of the bosh 1 and the shaft 2, 
there are cooling plates 6 such as for example known from applicant's 
Dutch patent NL-182158, arranged in vertically spaced rows. Each plate 6 
is mounted in the jacket 9, 9a and has connections exteriorly of the 
jacket for supply and discharge of the cooling liquid, which is typically 
water. 
In accordance with the present invention it is now proposed to provide a 
row of T-shaped transition cooling elements 7 in the wall of the shaft 
furnace and in the vicinity of mantle ring 4. These elements project 
inwardly from the jacket 9 of the furnace to near the interface 8 where 
the refractory lining of the bosh 1 forms with the steel jacket 9. Each of 
these cooling elements 7 comprise a stem 10 of a relatively small section, 
and a cross-bar 11 which extends in the circumferential direction of the 
furnace. In contrast with the plates 6 which extend to near the interior 
face of the lining, the transition cooling elements 7 extend inwardly so 
that its cross-bar 11 is at a location just above the inner periphery of 
the mantle ring 4, to provide the desired cooling at this transition zone. 
The furnace is provided with a plurality of the cooling elements 7 which 
are arranged in the wall of the furnace at regular intervals in the 
circumferential direction of the furnace, with the extremities of the 
cross-bars 11 positioned at short spacings from each other. In this 
embodiment, the cooling elements 7 are positioned in the wall of the 
furnace in such a way that they have a circumferentially staggered 
relationship, as Seen in plan view, relative to the cooling plates 6 of 
conventional type in the wall of the furnace in the row next above them 
(this row is not shown in FIG. 2). The cooling elements 7 have connections 
12, 13 for supply and discharge of cooling liquid, which can flow through 
the cooling elements. These connections 12, 13 are accessible on the outer 
side of the jacket 9 and, as FIG. 2 shows, project somewhat at an angle 
relative to the jacket 9a in order to avoid difficulties in connecting. 
The cooling elements 7 are copper castings, made in a conventional manner, 
similar to the cooling plates 6. To provide internal cooling liquid 
passages, there is a T-shaped vertical partition inside the element, which 
forms parallel inflow and outflow passages in the stem 10 and a 
circulation passage around the cross-bar 11 joining at its ends the inflow 
and outflow passages. 
Instead of the T-shape shown, the cooling elements 7 may have any suitable 
shape providing a circumferentially elongate portion at the desired 
cooling location.