Method and apparatus for correcting the falling path in a loading installation of a shaft furnace

The process is intended to compensate for the random movements and inclinations of a loading installation of a shaft furnace having a storage lock chamber which is carried by a framework independent of the shaft furnace and which is connected to the shaft furnace by use of a compensator. In accordance with this process, the lateral shifts of the head of the furnace in relation to the lock chamber are detected, and the storage lock chamber is inclined until the axis of the falling path of the charge material corresponds to the shifted central axis (0') of the furnace.

BACKGROUND OF THE INVENTION 
This invention relates to a process and apparatus for correcting the 
falling path of charge material in a loading installation for a shaft 
furnace. More particularly, this invention relates to a process and 
apparatus for compensating the random movements and inclinations of the 
path of falling charge material in a loading installation of a shaft 
furnace, comprising a storage lock chamber which is carried by a framework 
independent of the furnace; and which is connected to the furnace by means 
of a compensator. The present invention is particularly well suited for 
use in an installation of the central-loading type such as is disclosed in 
No. EP-B1-0,062,770, corresponding to U.S. Pat. No. 4,514,129, assigned to 
the assignee hereof, all of the contents of which are incorporated herein 
by reference. This prior installation comprises a stand-by hopper and a 
storage lock chamber, both of which are aligned on the central axis above 
the furnace. It is well known that, in the course of time, a blast furnace 
can become slightly inclined relative to its initial position under the 
effect of thermal expansion or local compression caused by the load. This 
causes the central axis of the falling path of the loading material 
falling from the storage lock chamber to no longer correspond to the axis 
of the furnace because the lock chamber does not undergo the movements of 
the furnace as it is supported by an independent framework. These relative 
movements between the furnace and the lock chamber are made possible by 
the compensator between the furnace head and the valve housing located 
under the lock chamber. 
Although this offset of the furnace head in relation to its initial or 
reference position is very slight, it is nevertheless sufficient to cause 
an off-center distribution of the loading material. Moreover, because the 
effects are cumulative for the successive layers and because a 
distribution chute (e.g. oscillating spout) is concerned, the effect of 
the offset is twofold since it is negative on one side and positive on the 
other side. 
SUMMARY OF THE INVENTION 
The above-discussed and other drawbacks and deficiencies of the prior art 
are overcome or alleviated by the process and apparatus of the present 
invention for correcting the falling path of charge material so that this 
path corresponds to the central axis of the furnace despite random 
movements and inclinations of the furnace. In accordance with the process 
of the present invention, in a first step, lateral shifts of the head of 
the furnace in relation to the lock chamber are detected. In a second 
step, the storage lock chamber is inclined until the axis of the falling 
path of the loading material corresponds to the central axis of the 
furnace. The storage lock chamber is preferably inclined by raising that 
side of the chamber in which the central axis of the furnace deviated from 
the initial central axis of reference, and by lowering the chamber on the 
opposite side thereof. 
The present invention also provides an apparatus for carrying out the 
correction process described above in an installation in which the lock 
chamber is supported by means of several balances. This apparatus includes 
means for raising or lowering each balance and a ring of detectors 
independent of the furnace. The detectors are arranged around the lower 
part of the compensator in order to determine the direction and extent of 
the deviation of the furnace head relative to the initial reference axis. 
The support means preferably comprises a threaded rod supporting a balance, 
the threaded rod being vertically shiftable via a casing; and the axial 
thread of a pinion seated in this casing by way of a bearing and rotated 
by means of an endless screw under the action of a motor. The threaded rod 
is associated with means preventing it from rotating, but allowing it to 
shift vertically. The motor causing the vertical movement of the threaded 
rod can be actuated manually or automatically under the control of the 
detectors detecting the offset of the furnace. 
The storage lock chamber can be carried by the balances or can be suspended 
on the balances. 
The above-discussed and other features and advantages of the present 
invention will be appreciated and understood by those of ordinary skill in 
the art from the following detailed description and drawings.

DESCRIPTION OF THE PREFERRED EMOBIDMENT 
Referring first to FIG. 1, the head of a shaft furnace is shown generally 
at 10 in which is located a device for distributing the loading or 
charging material (not shown), but which preferably consists of a rotary 
or oscillating distribution chute (such as is shown in above-mentioned 
U.S. Pat. No. 4,514,129). This chute is activated by means of a known 
driving mechanism represented diagrammatically by the reference numeral 
12. Arranged above furnace 10 and aligned on the central axis 0 of the 
furnace, are a corrugated compensator 14, a valve housing 16, a storage 
lock chamber 18 and a stand-by hopper 20. Everything which is above 
compensator 14 is supported by a framework consisting primarily of a 
horizontal supporting reinforcement 22 carried by several vertical 
pillars. In turn, the pillars are supported by a structure, which is 
independent of furnace 10 (for example the known square tower which is 
usually arranged around a shaft furnace). 
As explained in the Background section, the shaft furnace will move over 
the course of time so that eventually, its central axis 0 will shift into 
the position represented by 0', the new position of the furnace 10 being 
represented by dot-and dash lines on the left-hand side of the Figure. The 
offset "a" illustrating the extent of the shift of the furnace axis has 
been exaggerated in relation to the general dimensions of the installation 
for explanatory purposes. This offset "a" continues up to the region of 
compensator 14 which specifically allows for the transition between the 
axis 0' and the initial reference axis 0. 
To ensure central loading in the true axis 0' of furnace 10 despite this 
offset lock chamber 18 is inclined on the opposite side relative to the 
offset "a" in relation to the initial axis 0. For this purpose, lock 
chamber 18 is raised slightly on the left hand side in FIG. 2 and lowered 
slightly on the opposite side. As a result, lock chamber 18 will be 
inclined at an angle .alpha. relative to its initial position, until the 
center of its outflow orifice is in the extension of the true axis 0' of 
furnace 10. 
In FIG. 3, a preferred embodiment of an apparatus in accordance with the 
present invention for allowing the storage lock chamber 18 to incline is 
shown. Storage lock chamber 18 is suspended on reinforcement 22 by means 
of several, preferably four, balances. FIG. 3 illustrates diagrammatically 
the upper part of lock chamber 18 which is suspended on one of the 
balances 28. This balance can comprise, for example, a cage 30 containing 
a stress cell 32 (for example, a piezo-electric transducer). A yoke 34 
welded to the outer wall of lock chamber 18 passes through the bottom of 
cage 30 and rests on the head of cell 32. It will be appreciated that 
instead of a cell 32 being used to measure weight by means of a 
compression effect, it is also possible, to provide a cell which measures 
tensile stress. 
Balance 28 is suspended on the lower end of a rod 36 which passes through 
reinforcement 22. The lower part 38 of rod 36 and the passage orifice in 
reinforcement 22 for part 38 have Polygonal cross-sections to both prevent 
rod 36 from rotating about its longitudinal axis, as well as to allow rod 
36 to slide vertically. 
A casing 40 is provided on reinforcement 22 through which passes the upper 
part of rod 36 having an external thread 42. Inside casing 40 is a 
reduction unit actuating rod 36 in the vertical direction. In the 
illustrated example, this reduction unit is composed of an endless-screw 
gear comprising a screw 44 acting on the ring of a pinion 46 seated inside 
housing 40 by way of bearings 48. Pinion 46 has an axial passage equipped 
with a thread which is engaged with threaded part 42 of rod 36. The 
arrangement is therefore such, that as a result of the rotation of pinion 
46, a rotation of endless screw 44 causes rod 36 to be raised or lowered 
depending on the direction of rotation of screw 44. Screw 44 can be driven 
by means of an electric motor 45. 
A flexible strip connecting the upper part of lock chamber 18 to the 
reinforcement 22 is identified at 50. Strip 50 ensures the horizontal and 
slewing stability of lock chamber 18, while at the same time preserving 
its freedom of vertical movement to allow weighing by means of balances 
28. 
To ascertain the extent to which it is necessary to raise or lower rod 36 
in order to incline the axis of lock chamber 18 to reestablish central 
falling, a series of detectors 51 is advantageously arranged around the 
lower part of compensator 14. In this particular case, detectors 51 can be 
distance detectors which are known per se, and which are mounted 
independently of the furnace so as not to undergo the movements of the 
latter. These detectors 51 make it possible to measure movement of 
compensator 14 towards or away from them and thus provide an indication as 
to the extent of the offset "a". Of course, that detector which supplies 
the largest measuring signal represents the orientation of the offset "a". 
When these measurements are known, it is possible to manually actuate each 
of the motors acting on the endless screws 44, until the axis of lock 
chamber 18 is inclined at an angle a relative to the vertical axis. 
The operation of inclining the lock chamber can be controlled, that is, the 
moment when the desired inclination is reached can be determined in 
various ways. It is possible, for example, to mount the detectors intended 
for making the extent and orientation of the offset "a" on a circular 
support integral with the fixed upper collar of compensator 14. This means 
that the inclination of lock chamber 18 causes a horizontal offset of the 
support of the detectors and consequently of the detectors themselves. The 
operation of inclining lock chamber 18 can therefore be controlled 
manually, until compensator 14 is Perfectly cylindrical once again, in 
other words, until the measuring signals supplied by the detectors have 
disappeared. 
It will be appreciated that the signals representing the offset a may be 
used to calculate the angle of inclination .alpha. of the lock chamber 
necessary for compensating this offset and to automatically actuate (under 
the control of a computer 54), the motors which make it possible to carry 
out the inclination. 
The above description refers to a lock chamber which is suspended on 
reinforcement 22 by means of balances. However, it is also possible to use 
the present invention on a carried lock chamber, that is a lock chamber 
resting on reinforcement 22 by means of balances. In this case, the 
balances are carried by the upper ends of rods 36. 
While preferred embodiments have been shown and described, various 
modifications and substitutions may be made thereto without departing from 
the spirit and scope of the invention. Accordingly, it is to be understood 
that the present invention has been described by way of illustrations and 
not limitation.