EP2601319B1

EP2601319B1 - Distribution chute

Info

Publication number: EP2601319B1
Application number: EP11732496.2A
Authority: EP
Inventors: Emile Lonardi; Guy Thillen; Dominique Rocchi; Serge Devillet; Claude Thinnes
Original assignee: Paul Wurth SA
Current assignee: Paul Wurth SA
Priority date: 2010-08-06
Filing date: 2011-07-18
Publication date: 2014-06-18
Anticipated expiration: 2031-07-18
Also published as: BR112013002927A2; LU91716B1; WO2012016818A1; KR101773454B1; PL2601319T3; CN103052721B; JP2013532775A; JP5764658B2; TWI571516B; UA107026C2; RU2570258C2; EP2601319A1; RU2013109733A; TW201211266A; CN103052721A; KR20130137605A

Description

Technical field

The present invention generally relates to distribution chutes to be used in a bulk material distribution device for distributing bulk material in an enclosure such as a metallurgical reactor and, in particular, a blast furnace. More specifically, the invention relates to a distribution chute that has a chute body defining a channel with a bent portion that diverts bulk material from a first flow direction, along which it flows immediately after impact on the chute in an inlet portion thereof, to a second flow direction with which the flow leaves the chute outlet.

Background Art

In the specific case of blast furnaces, charging installations of the so-called "bell-less" type have found widespread use. These charging installations are arranged at the furnace top and comprise a distribution device and have a distribution chute as a key component. The distribution device is typically configured for rotating the chute about the vertical furnace axis and for pivoting the chute about a perpendicular horizontal axis. During the charging procedure, bulk charge falls vertically onto the distribution chute that distributes the material in circumferential and radial direction according to its rotational and pivotal position. Accordingly, virtually any desired charge material profile can be achieved on the charging surface.
Due to the abrasive effect of large quantities of bulk material sliding over a distribution chute, the chute is subjected to considerable wear and has to be replaced regularly by a new or refurbished chute. A very widespread chute design is known e.g. from European Patent EP 0 640 539 . This patent proposes a longitudinally straight and generally trough-shaped chute body with special retention chambers that retain a layer of bulk material on the chute to minimize wear.
An effect that worsens wear of the chute is the relatively large angle of impact of material on the chute, when the chute is not in a nearly vertical (center-charging) position. In other words, with typical charging profiles, a large majority of the pivotal positions of the chute imply a considerable impact load, which adds to sliding friction as a cause of abrasive wear. In fact, with a typical rectilinear straight chute as proposed in EP 0 640 539 , the angle of impact of material onto the chute corresponds to the chute inclination angle, which may be well above 50° (from vertical) for the radially outermost charging position.
In order to reduce wear of the most wear-prone portion, i.e. the impact portion of the chute, it has therefore been proposed to provide a chute body that deviates from the typical straight shape. Simply speaking, in such chutes the impact portion forms a more acute angle with the vertical falling direction than the outlet portion, which determines the degree of radial flow deviation (charging radius). In other words, the direction of flow after impact is generally steeper than the direction of flow at the outlet. Accordingly, such a chute achieves nearly the same deviation of flow whilst significantly reducing impact load. Furthermore, the flow is decelerated to a lesser degree when impacting at a more acute angle. Therefore, as another advantage, material has a higher exit velocity at the outlet so that the chute may achieve the same radius of charging at a shorter length of the chute or at a smaller angle of chute inclination, with the latter option further reducing wear.
Distribution chute bodies that define a channel with a bent portion that diverts the flow from a first flow direction immediately after impact on the chute to a less steep second flow direction at the outlet said flow are known for instance from Japanese patent applications JP 59-020412 and JP 59-031807 .
JP 59-020412 proposes a generally trough-shaped chute body with a downstream portion that is generally straight (Fig.2: A-B) and an upstream portion (Fig.2: C-B) that is curved to an arcuate shape having a center of curvature at a radius of 0.5-4.0 times, more preferably 0.5-3.0 times the chute length. Accordingly, the flow of charge material changes its direction gradually along the curved shape of the chute. Manufacturing of such a curved shape is however uneconomical or likely to result in a relatively weak construction. JP 59-031807 proposes a very similar design. This trough-shaped chute body merely differs in that the upstream portion is formed of a succession of straight segments, which contact tangentially with an arc having a radius of 0.5-4.0 times the chute length. Accordingly, the segments proposed in JP 59-031807 approximate the aforementioned curved shape of JP 59-020412 whilst being likely more economical in terms of manufacturing.
Another chute body with a downstream portion that is less steep than the upstream portion is proposed in WO 2009/037508 . The latter chute has a generally frusto-conical construction and is specifically suited for a so-called gimbal-type charging device, in which the chute pivots in cardanic manner about two perpendicular horizontal axes. Besides being incompatible with rotary and pivotal charging devices, this chute is held to be subject to more rapid wear on impact point.
Despite their obvious benefits of increased service life due to reduced wear and potentially shorter chute length, distribution chutes with progressive material flow deviation as discussed above have not been widely adopted, at least in the field of metallurgical reactors.
It is theorized that this lack of acceptance is due, among others, due to difficulties related to providing a construction of the chute body that is both economical and sufficiently strong for reliably withstanding the considerable loads exerted onto the chute, including charge material weight and dynamic loads exerted during rotation and pivoting of the chute.

Technical problem

It is therefore an object of the present invention to provide a strong and economical configuration of a distribution chute of the type that has a chute body defining a flow channel with a bent upstream portion.

General Description of the Invention

The invention proposes a distribution chute of the rotate-and-pivot type. It may be used in a bulk material distribution device, in particular for a charge material distribution device of a metallurgical reactor such as, e.g., a shaft furnace. The distribution chute comprises a chute body (i.e. the load-supporting structure of the distribution chute) having therein a channel with an inlet for receiving a flow of bulk material and an outlet for discharging the bulk material. In operation, the channel conveys the bulk material from the inlet to the outlet. The channel has a bend to divert the flow of material from a first flow direction in the inlet into a second flow direction in the outlet. According to the invention, the chute body is assembled of at least an upstream part, which comprises the inlet, and a downstream part, which comprises the outlet and which is fixed to the upstream part (i.e. the upstream and downstream parts are secured against relative displacement). The downstream part defines a straight portion of the channel, whereas the upstream part defines the inlet and the bend of the channel. Furthermore, the upstream part is thick-walled with respect to the (more thin-walled) downstream part.
Those skilled will appreciate that in such distribution chute the major part of the load exerted on the distribution chute by the impacting bulk material is taken by the thick-walled upstream part of the chute body. As the upstream part of the chute also comprises the bend, most of the deflecting forces needed to change the trajectory of the bulk material at the transition between the first and the second flow direction are also exerted by the upstream part. In the downstream part of the chute, the material follows an essentially rectilinear trajectory (in the reference system of the chute). Consequently, the wall strength of the downstream part has been chosen smaller than that of the upstream part. The result is a distribution chute, which exhibits high mechanical rigidity, which imparts less torque on the chute bearings thanks to the construction of the radially outward downstream part, and which is manufacturable economically.
As used herein, the first flow direction corresponds to the overall tangential direction (in the vertical central plane of the distribution chute) of the bottom of the inlet, where the flow of bulk material hits the distribution chute - at least for high discharge angles, i.e. above about 45°-, whereas the second flow direction corresponds to the overall tangential direction (in the vertical central plane of the distribution chute) of the bottom of the outlet. As used herein, the term "discharge angle" designates the angle between the distribution chute outlet and the vertical direction.
According to a preferred embodiment of the invention, the upstream part is made of cast metal, e.g. cast iron or cast steel. Those skilled will appreciate that thanks to the use of casting techniques, one gains in terms of versatility of shape of the upstream part. In other words, there are fewer limitations to the design of the chute than in the prior art, which makes it easier to tailor the chute body in accordance with the application, the available space and other parameters of operation. Most preferably, the downstream part comprises one or more welded curved steel plates.
The inlet of the channel of the distribution chute is preferably provided on the upstream part as an annular collar. The inlet is thus formed as a tubular section (which encloses the axis of the inlet circumferentially). The annular collar reinforces the upstream part, allowing it to take up higher torque without significant deformation.
According to a preferred embodiment of the distribution chute, the downstream part comprises a tubular section that provides the outlet. As those skilled will appreciate, this reduces (or eliminates) lateral overflow of the bulk material, which ultimately results in an improved control of the charge distribution underneath the chute. Most preferably, the downstream part tapers from the coupling with the upstream part towards the outlet.
Preferably, the channel has a first channel axis (corresponding to the first flow direction) in the inlet and a second channel axis (corresponding to the second flow direction) in the outlet, between which the bend in the upstream part defines an angle. This angle is preferably in the range from 15 to 45°, more preferably in the range from 20 to 40°.
The bend in the upstream part may be sharp (abrupt). Alternatively, the bend may define a curved transition between the channel bottoms in the inlet and the outlet. It will be appreciated that three-dimensionally curved surfaces can easily be achieved using casting techniques for the manufacturing of the upstream part.
To assemble the upstream part with the downstream part, the upstream part comprises a coupling end opposite the inlet (with respect to the bend). The downstream part is preferably inserted into the coupling end, e.g. up to the bend, and fixed in that position using screws, bolts, rivets, weldings or any other suitable fixation means. To achieve high stability, the length of the overlap of the coupling end and the downstream part preferably amounts to at least 20%, e.g. between 20 and 40%, of the total length of the downstream part.
According to a preferred embodiment of the invention, the distribution chute comprises an insert in the upstream part and/or in the downstream part, which insert comprises retention chambers (stone boxes), which are open to the channel so as to be able to fill up with bulk material for protection of the distribution chute against wear. Preferably, the inserts are arranged in such a way that any surface on which the entering flow of bulk material may impinge at an angle of at least about 30° is protected with a stone box. This way, one ensures that the regions on the channel surface that are most susceptible of being eroded by the impacting material flow are appropriately protected. It will be appreciated that the insert(s) may be exchanged separately from the chute body when they are worn. This helps to keep servicing costs low. It should be noted that instead of inserts in the form of retention chambers, it is also possible to provide inserts in the form of cast or ceramic wear plates.
Preferably, the outlet of the distribution chute is formed by a wear-resistant slide insert within the downstream part. In contrast to the zone equipped with retention chambers, the slide has an essentially smooth surface in the outlet in order to discharge an as concentrated and homogeneous stream of bulk material as possible.
The chute body preferably has an opening on the interior side of the bend. Advantages of such an opening are, for instance, a reduction of the weight of the chute without compromising wear-resistance and the removal of an "obstacle" to the incoming flow of bulk material when the chute is oriented substantially vertical (i.e. when the discharge angle is less than about 15°) for center-charging.
The distribution chute may comprise handling trunnions on the upstream part, on which the distribution chute may be supported by a tilting mechanism. The handling trunnions are preferably integrally formed with the upstream part.
A preferred aspect of the invention concerns a metallurgical reactor, e.g. a shaft furnace, comprising a charging installation with a charge material distribution device equipped with a distribution chute as described herein.

Brief Description of the Drawings

Further details and advantages of the present invention will be apparent from the following non-limiting detailed description of a preferred embodiment, with reference to the attached drawings, wherein:

Fig. 1 is a perspective view illustrating a distribution chute according to a preferred embodiment of the invention;
Fig. 2 is a vertical cross-sectional view of a charging device equipped with a distribution chute according to Fig.1;
Fig. 3 is top view of the distribution chute of Fig.1.

Identical numerals are used throughout these drawings to identify identical of functionally similar parts or elements.

Detailed Description with respect to the Drawings

A distribution chute 10 according to a preferred embodiment of the invention is generally shown in Fig. 1. The distribution chute 10 comprises a chute body 12, which is essentially composed of two structural parts: cast-steel upstream part 14 and downstream part 16, which is made from curved steel plates.
The distribution chute 10 may be suspended to a charging device with trunnions 18 that are integrally formed with the upstream part 14, on the outside of the inlet 20 thereof. The inlet 20 is configured as a (circumferentially closed) tubular channel portion. The end opposite the inlet of the upstream part 14 is configured as a coupling portion, to which the downstream part is fixed. The upstream and downstream parts 14, 16 delimit in their interior a channel 22 that conveys bulk material entering the distribution chute 10 through the inlet 20 to the outlet 24, from which the material is then discharged, e.g. into the charging zone of a shaft furnace.
Fig. 2 shows a shaft furnace charging device equipped with the distribution chute of Fig. 1. The distribution chute 10 is pivotally suspended with its trunnions 18 to a rotatable structure 25. The rotatable structure 25 is rotatably supported in a stationary housing 30 by means of large diameter roller bearings 32. The inner race of roller bearings 32 is fixed to a top end flange 34 of the rotatable structure 25 whereas the outer race of roller bearings 32 is fixed to a top plate 36 of the stationary housing 30. The roller bearings 32 are configured so that the rotatable structure 25 and therewith the distribution chute 10 can rotate about the substantially vertical axis 38, which usually coincides with the central axis of the furnace. A central feeder spout 26 is centered on axis 38 and defines a passage for bulk material through the top plate 36. The charging device of Fig. 2 achieves distribution of charge material in the charging zone of the shaft furnace by rotating the distribution chute 10 about axis 38 and by varying the pivoting angle of the distribution chute 10 about pivot axis 39. Pivot axis 39 is generally perpendicular to axis 38. Details of mechanisms suitable for rotating and pivoting the distribution chute 10 are not shown in the figures and not further described herein. Those interested in such mechanisms may e.g. refer to US 3,880,302 .
When bulk material (e.g. coke, ore, pellets, etc.) is fed through the feeder spout 26 onto the distribution chute 10, it strikes the bottom of the channel 22. The impact location depends on the tilting angle of the distribution chute 10. For a high discharge angle (which is herein the angle β between the velocity vector of the bulk material at the outlet 24 of the distribution chute 10 and the vertical axis 38), the bulk material impacts on the channel bottom close to the inlet 20. With decreasing discharge angle, the impact location moves away from the inlet 20 towards the outlet 24 of the chute 10. The channel 22 has a bend 28 in the upstream part 14 in order to progressively divert material that hits the channel bottom in the inlet 20 from the vertical to the discharge direction. Material hitting the channel bottom in the inlet 20 is first diverted into a first flow direction substantially parallel to the bottom of the inlet. At the bend 28, the material is then diverted into a second flow direction parallel to the bottom of the outlet 24. The bend 28 defines an angle α in the range from 20 to 40° between the channel bottom of the inlet and the channel bottom of the outlet.
The downstream part 16 and the upstream part 14 are fixed to one another at the coupling portion 40 of the upstream part 14. The coupling portion 40 is located opposite the inlet 20 with respect to the bend 28. The upper end of the downstream part 16 is inserted into the coupling portion 40 up to the bend 28 and fixed in that position. In the illustrated example, the length of the overlap of the coupling portion 40 and the downstream part 16 amounts to about one third of the total length of the downstream part 16.
As best illustrated in Figs. 2 and 3, the distribution chute 10 comprises a first insert 42 that defines retention chambers in the upstream part 14 and a second insert 44 that defines retention chambers in the downstream part 16. The retention chambers are open to the channel so as to be able to fill up with bulk material and thus to protect the distribution chute against wear. The inserts are arranged in the regions that are most susceptible to erosion by the impacting bulk material. Each insert 42, 44 includes a plurality of transverse plates 46 that are inclined in a direction generally opposite to the flow of the bulk material. One or more longitudinal plates 48 subdivide the retaining chambers in the transversal direction of the channel in order to ensure a more uniform filling of the retaining chambers in the lateral regions of the chute 10. Further details on possible configurations of the retention chambers can e.g. be found in EP 0 640 539 .
The outlet 24 of the distribution chute 10 is formed by a wear-resistant slide insert 50 arranged within the downstream part 16. In contrast to the zones equipped with retention chambers, the slide insert 50 forms an essentially smooth and slightly tapering channel portion in the outlet in order to discharge an as concentrated and homogeneous stream of bulk material as possible. The surface formed by the slide insert is essentially aligned with the top edges of the transversal plates 46 and the longitudinal plates downstream of the bend 28. The slope of the outlet determines the discharge angle β, which may be varied between about 10° (center-charging position) and about 50° by pivoting the chute about the pivot axis 39.
The chute body 12 has an opening 52 on the interior side of the bend 28. In the vertical cross sectional view of Fig. 2, one sees that the opening 52 is arranged so as to define a recess that allows increasing the inclination angle of the chute 10 without touching the radially inner edge 54 of the bottom end flange of the rotatable structure 25. Another advantage of the opening 52 is that in the "center-charging" position, the bulk material may fall straight through the chute 10 without substantial deflection at the bend 28 by the roof of the channel 22. Furthermore, the opening could even serve as an overflow in certain situations.
In the illustrated distribution chute, the bend in the upstream part corresponds to a sharp transition between essentially straight channel portions. Those skilled will appreciate that the bend could also be implemented as a smoothly curved transition between the channel bottoms in the inlet and the outlet.
While a specific embodiment has been described in detail, those with ordinary skill in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangement disclosed is meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Legend:

10: Distribution chute
12: Chute body
14: Upstream part
16: Downstream part
18: Handling trunnions
20: Inlet
22: Channel
24: Outlet
25: Rotatable structure
26: Feeder spout
28: Bend
30: Stationary housing
32: Roller bearing
34: Top end flange
36: Top plate
38: Vertical axis
39: Pivot axis
40: Coupling portion
42: First insert with retention chambers
44: Second insert with retention chambers
46: Transverse plates
48: Longitudinal plate
50: Slide insert
52: Opening
54: Edge of bottom end flange

Claims

A distribution chute (10) for a bulk material distribution device, in particular for a charge material distribution device of a metallurgical reactor such as a shaft furnace, said distribution chute comprising:
a chute body (12) having a channel (22) with an inlet (20) for receiving a flow of bulk material and an outlet (24) for discharging said bulk material, said channel (22) for conveying said bulk material from said inlet (20) to said outlet (24), said channel (22) having a bend (28) to divert said flow from a first flow direction in said inlet (20) into a second flow direction in said outlet (24),

characterized in that

said chute body (12) is assembled of at least an upstream part (14), which comprises said inlet (20), and a downstream part (16), which comprises said outlet (24), said downstream part (16) defining a straight portion of said channel (22) and said upstream part (14) defining said inlet (20) and said bend (28) of said channel (22), said upstream part (14) comprising a coupling end (40) opposite said inlet (20) with respect to said bend (28), said downstream part (16) being inserted into said coupling end (40), preferably up to said bend (28), and fixed to said upstream part (14) in that position;

and in that said upstream part (14) is thick-walled with respect to said downstream part (16).
Distribution chute (10) as claimed in claim 1, wherein said upstream part (14) is made of cast metal, preferably cast iron or cast steel.
Distribution chute (10) as claimed in claim 2, wherein said downstream part (16) comprises one or more welded curved steel plates.
Distribution chute (10) as claimed in any one of claims 1 to 3, wherein said inlet (20) is provided on said upstream part (14) as an annular collar.
Distribution chute (10) as claimed in any one of claims 1 to 4, wherein said downstream part (16) comprises a tubular section providing said outlet (24).
Distribution chute (10) as claimed in any one of claims 1 to 5, wherein said downstream part (16) tapers from a coupling with said upstream part (14) towards said outlet (24).
Distribution chute (10) as claimed in any one of claims 1 to 6, wherein said channel (22) has a first channel axis in said inlet (20) and a second channel axis in said outlet (24) and wherein said bend (28) in said upstream part defines an angle, preferably in the range from 15-45°, more preferably in the range from 20-40°, between said first and second channel axes.
Distribution chute (10) as claimed in claim 7, wherein said bend (28) in said upstream part (14) defines a curved transition between said first and second channel axes.
Distribution chute (10) as claimed in any one of claims 1 to 8, wherein the length of the overlap of the coupling end (40) and the downstream part (16) amounts to from 20 to 40% of the total length of the downstream part (16).
Distribution chute (10) as claimed in any one of claims 1 to 9, comprising an insert (42, 44) in said upstream part (14) and/or said downstream part (16), said insert (42, 44) comprising retention chambers, which are open to said channel (22) so as to be able to fill up with bulk material for protection of the distribution chute (10) against wear.
Distribution chute (10) as claimed in any one of claims 1 to 10, wherein said chute body (12) comprises a wear-resistant slide insert (50), which forms said outlet (24), within said downstream part (16).
Distribution chute (10) as claimed in any one of claims 1 to 11, wherein said chute body (12) has an opening (52) on the interior side of said bend (28).
Distribution chute (10) as claimed in any one of claims 1 to 12, comprising handling trunnions (18) on said upstream part (14), said handling trunnions (18) being preferably intergrally formed with said upstream part (14).
Metallurgical reactor, e.g. a shaft furnace, comprising a charging installation with a charge material distribution device equipped with a distribution chute (10) as claimed in any one of claims 1 to 13.