Patent Application
20140246815
The present invention generally relates to a blast furnace installation, in particular comprising blast furnace and a chute transmission gearbox arranged thereon. More particularly, the invention concerns the connection between the chute transmission gearbox and the blast furnace. The present invention further relates to a method for installing a chute transmission gearbox on a blast furnace.
Blast furnaces of the bell less top® design comprise a chute transmission gearbox between the top cone of the blast furnace and the material charging hoppers. Such a chute transmission gearbox comprises ball bearings for the rotation of the associated rotary chute, which is used to evenly distribute charge material into the blast furnace. The correct installation of the chute transmission gearbox on the top of the blast furnace is of particular importance. An incorrect installation may have devastating consequences on the correct functioning of the ball bearings, and consequently of the chute transmission gearbox. Indeed, the seat receiving the chute transmission gearbox must be precision engineered and must satisfy rather strict tolerances regarding flatness.
Generally, the top cone of the blast furnace is provided with a top cone ring for receiving a connection flange of the chute transmission gearbox thereon. Both the top cone ring and the connection flange must be machined so that they fit together perfectly. In order to further avoid any gas from escaping between the top cone ring and the chute transmission gearbox, a sealing compound is applied on the top cone ring before installation. In view of the strict tolerances that have to be respected, it is generally necessary to adapt the top cone ring during erection or revamping of the blast furnace. Such on-site adaptation of the top cone ring is rather time-consuming and thus expensive. In some circumstances it may furthermore be particularly difficult to meet the necessary tolerances, thus with the risk of installing the chute transmission gearbox without respecting the necessary tolerances and therefore endangering the correct functioning of the rotary chute.
A blast furnace installation is provided with an improved means for adjusting and aligning the chute transmission gearbox on a blast furnace. Also provided is a method for installing a chute transmission gearbox on a blast furnace, wherein adjusting and aligning the chute transmission gearbox is improved.
A blast furnace installation comprises a blast furnace and a chute transmission gearbox; the blast furnace comprising a top cone with a top cone ring arranged thereon for receiving a connection flange of the chute transmission gearbox. The connection flange is directly fixed onto the top cone ring by fixing means for establishing a firm connection between the top cone ring and the connection flange. According to an aspect of the present invention, the connection flange is fixed to the top cone ring in three separated fixation regions, each fixation region comprising one or more fixing means. According to a further aspect of the present invention, the blast furnace installation also comprises a flexible sealing element arranged around the perimeter of the connection between the top cone ring and the chute transmission gearbox.
In essence, the chute transmission gearbox is carried by the top cone ring, without paying particular attention to how well the connection flange sits on the top cone ring. Irrespective of the presence of gaps between the connection flange and the top cone ring, the fixing means in the fixation regions are used to establish a firm connection between the top cone ring and the connection flange. In other words, small gaps may exist between top cone ring and the connection flange of the chute transmission gearbox. According to the present invention, such small gaps are not problematic and a perfect fit between connection flange and top cone ring is not necessary.
In prior art installations, however, any gaps between the connection flange of the chute transmission gearbox and the top cone ring constitute a major problem. As the chute transmission gearbox is connected to the top cone ring around essentially the whole of its perimeter, in the region of the gap, the chute transmission gearbox may be deformed by the fixing means. Such deformation is of course detrimental to the correct functioning of the ball bearings and thus of the rotary chute. Furthermore, as the sealing is achieved by means of a sealing compound between the two contact surfaces, a gap therein allows gas to escape through the gap. Thus it is, in prior art installations, essential to adapt the top cone ring and/or the connection flange on site so as to avoid such gaps.
According to the present invention, on the other hand, the fixation takes place in three fixation regions and gaps are allowed to exist. Consequently, the only intervention needed is to align the chute transmission gearbox horizontally to meet the strict installation tolerances. Instead of machining the top cone ring and/or the connection flange on site so as to eliminate such gaps, the present invention indeed suggests to fix the connection flange to the top cone ring without necessitating a perfect fit between the connection flange and the top cone ring. Thus, it is considerably easier, faster and cheaper to install the chute transmission gearbox. The inventors have found that fixing the chute transmission gearbox in exactly three fixation regions only, leads to fewer deformations in the chute transmission gearbox, which in turn leads to fewer stresses on the ball bearings of the chute transmission gearbox. A correct installation of the chute transmission gearbox is therefore achieved more easily and the correct functioning of the gearbox can be guaranteed. The lifetime of the gearbox may also be prolonged.
Furthermore, the flexible sealing element arranged around the perimeter of the connection between the top cone ring and the chute transmission gearbox prevents any gas from escaping through any possible gaps between the connection flange and the top cone ring. Such a flexible sealing element applied on the outside after correct placement of the chute transmission gearbox allows replacing the previously used, rather delicate sealing method of applying a sealing compound on the top cone ring before positioning of the chute transmission gearbox.
Advantageously, the collective space covered by the fixation regions does not exceed 180° of the angular surface of the top cone ring. By limiting the number and size of the fixation regions, the stresses and deformations that the chute transmission gearbox may be exposed to is greatly reduced. Furthermore, the fixation regions are preferably arranged equidistantly from one another.
The fixing means in the fixation regions may comprise a bolt and nut connection between the top cone ring and the connection flange. Each fixation region may comprise between 5 and 30 fixing means.
According to a preferred embodiment, shim plates may be provided between the top cone ring and the connection flange. Such shim plates are preferably primarily used in the fixation regions for carrying out the horizontal alignment of the chute transmission gearbox on the top cone ring. In addition, shim plates may be used outside of the fixation regions to reduce the gaps between the chute transmission gearbox and the top cone ring. Due to the presence of the flexible sealing element, the shim plates need not fill the gaps in a gastight manner. Thus, installation of the shim plates can be effected quickly and efficiently.
Advantageously, the flexible sealing element comprises a flexible sheet arranged between a first connecting portion and a second connecting portion, the first connecting portion being welded to one of the top cone ring and the connection flange.
Before and during the installation process, a bracketing device is preferably provided between the first and second connecting portions for connecting the second connecting portion to the first connecting portion. The flexible sheet may be pre-stressed; in which case, the bracketing device maintains the flexible sheet in its pre-stressed state.
After the installation process, the second connecting portion is preferably welded to the other one of the top cone ring and the connection flange.
Thus, the flexible sealing element may initially be provided on the top cone ring. In this case, the first connecting portion is initially welded to the top cone ring and, after installation, the second connecting portion is welded to the connection flange. Preferably, however, the flexible sealing element is initially provided on the connection flange, wherein the first connecting portion is initially welded to the connection flange and, after installation, the second connecting portion is welded to the top cone ring.
The present invention also relates to a method for installing a chute transmission gearbox on a top cone of a blast furnace, the method comprising the steps of:
welding a top cone ring on the top cone;
placing the chute transmission gearbox on the top cone ring;
adjusting and horizontally aligning the chute transmission gearbox on the top cone ring in three fixation regions;
connecting a flexible sealing element around the perimeter of the connection between the top cone ring and the chute transmission gearbox; and
fixing the chute transmission gearbox to the top cone ring in of the three fixation regions.
The present method allows an installation without worrying about any gaps that may exist between the chute transmission gearbox and the top cone ring. Indeed, as the flexible sealing element ensures that the connection is gastight, there is no longer any need for the chute transmission gearbox to sit exactly on the top cone ring along the whole of its circumference. The fixing of the chute transmission gearbox to the top cone ring is limited to the three fixation regions without requiring a perfect fit of the connection flange on the top cone ring. This leads to an easier, quicker and cheaper installation of the chute transmission gearbox.
The adjusting and horizontally aligning of the chute transmission gearbox on the top cone ring in the three fixation regions may comprise the additional step of providing shim plates between the top cone ring and the connection flange.
It should be noted that the step of connecting the flexible sealing element may be carried out before or after the step of fixing the chute transmission gearbox to the top cone ring, both being within the scope of the present invention.
Preferably, before installation, a flexible sealing element is provided, the flexible sealing element comprising a flexible sheet arranged between a first connecting portion and a second connecting portion, the first connecting portion being welded to one of the top cone ring and the connection flange. Furthermore, a bracketing device is then provided between the first and second connecting portions for connecting the second connecting portion to the first connecting portion. The flexible sealing element can thus be mounted before installation of the chute transmission gearbox, but due to the bracketing device, the flexible sealing element remains tucked away out of the connection regions.
Advantageously, the step of connecting the flexible sealing element comprises removing the bracketing device and welding the second connecting portion to the other one of the top cone ring and the connection flange. Once the chute transmission gearbox has been correctly aligned on the top cone ring, the bracketing device can be removed such that the flexible sealing element can extend from the top cone ring to the connection flange. The subsequent welding of the second connecting portion to the other one of the top cone ring and the connection flange creates a gastight seal preventing any gas from escaping through the gap between the top cone ring and the connection flange of the chute transmission gearbox.
The flexible sealing element replaces the rather more delicate sealing, which comprises applying a sealing compound between the top cone ring and the connection flange. It should be noted that the flexible sealing element as disclosed herein may be used irrespective of how the connection flange rests on the top cone ring. In other words, the present sealing arrangement may also be used in connection with any other, possibly state of the art, connection between chute transmission gearbox and top cone ring.
A protection cord is preferably placed between the first and second connecting portions before welding and removed after welding. Such a protection cord, which preferably comprises ceramic material, protects the flexible sheet from any weld spatter during welding, thus preventing the flexible sealing element from being damaged during the welding process.
Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:
A blast furnace installation comprises a blast furnace with a furnace shaft, which has, in an upper region, a top cone 12 with a central opening 14 for feeding charge material into the furnace shaft. A charging installation 16 is arranged centrally above the furnace shaft for feeding charge material into the blast furnace. Such a charging installation 16 is typically of the bell less top® type and comprises one or more material hoppers 18 and a chute transmission gearbox 20 carrying a rotary chute 22. The chute transmission gearbox 20 comprises a central passage for allowing for the charge material to flow from the hoppers 18 arranged above the chute transmission gearbox 20 through the central passage onto the rotary chute 22. The latter rotates so as to evenly distribute the charge material in the furnace.
For the rotation of the rotary chute 22, the chute transmission gearbox 20 is provided with ball bearings (not shown). The fixation of the chute transmission gearbox 20 on the top of the top cone 12 must be effected in a precise manner. A top cone ring 24, which is configured to serve as a seat for the chute transmission gearbox 20, is welded to the top of the top cone 12. Such a top cone ring 24 has an opening 26 in alignment with the opening 14 of the top cone 12. The chute transmission gearbox 20 comprises on its lower portion a connection flange 28, which is designed to rest on the top cone ring 24.
The present invention is more particularly concerned with the connection between the connection flange 28 and the top cone ring 24. This connection can be more closely described by referring to
The chute transmission gearbox 20 comprises three fixation regions 30, 30′, 30″, each having a number of fixing means 32. The fixing means 32, preferably in the form of a bolt and nut connection, creates a firm connection between the top cone ring 24 and the connection flange 28 so as to securely fix the chute transmission gearbox 20 to the top cone 12 of the blast furnace. In the regions between the fixation regions 30, the chute transmission gearbox 20 may comprise access doors 34, 34′, 34″.
According to the present invention, the fixation of the chute transmission gearbox 20 to the top cone ring 24 takes place in the three fixation regions 30, 30′, 30″ only. Although the horizontal alignment of the chute transmission gearbox 20 still needs to meet strict installation tolerances, there no longer needs to be a perfect fit between the connection flange 28 and the top cone ring 24. In the fixation regions 30, 30′, 30″ and/or in the regions outside of the fixation regions 30, 30′, 30″, small gaps may exist between top cone ring 24 and the connection flange 28. Unlike in prior art installations, where the top cone ring 24 and/or the connection flange 28 must be machined to eliminate such gaps, the present invention allows the gaps to remain. The alignment of the chute transmission gearbox 20 on the top cone ring 24 is simplified by the fact that the necessary tolerances can be met without necessarily having to create a perfect fit. In the three fixation regions 30, 30′, 30″, the top cone ring 24 is horizontally aligned on the connection flange 28, possibly with the use of shim plates (not shown) in order to meet the strict installation tolerances without however worrying about achieving strict gas tightness.
Any gaps that may exist do not constitute a problem. Indeed, as the present invention introduces a flexible sealing element, a gastight connection is not necessary between the surfaces of the connection flange 28 and the top cone ring 24.
The flexible sealing element can be more closely described by referring to
The flexible sealing element 36 may, as shown in
Once the chute transmission gearbox 20 has been correctly adjusted and the connection flange 28 is in contact with the top cone ring 24, possibly via shim plates inserted in any gaps, the bracketing device 44 can be removed in order to allow the second connecting portion 42 to be connected to the top cone ring 24.
As shown in
The welding of the second connecting portion 42 to the top cone ring 24 creates a gastight seal preventing any gas from escaping through the gaps between the top cone ring 24 and the connection flange 28 of the chute transmission gearbox 20.
| Number | Date | Country | Kind |
|---|---|---|---|
| 91 885 | Oct 2011 | LU | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2012/069697 | 10/5/2012 | WO | 00 | 4/11/2014 |
