EP1105542B1 - Shaft furnace - Google Patents

Description

The invention relates to a shaft furnace, in particular a direct reduction shaft furnace a bed of lumpy material, in particular iron oxide and / or sponge iron Containing lumpy goods, which can be placed in the shaft furnace from above and with in one level arranged plurality of gas inlet openings for a reducing gas in the Area of the lower third of the shaft furnace, the shaft furnace outside by one Annular space is surrounded, which down through gas supply channels with the Gas inlet openings is connected.

Shaft furnaces, in particular direct reduction shaft furnaces of the type described above are often known from the prior art. One such, essentially as a cylindrical one Hollow-body shaft furnace contains, for example, a bed of iron oxide and / or lumpy material containing iron sponge, the material containing iron oxide in the upper part of the shaft furnace. By several on the scope of the Gas inlet openings arranged in the shaft furnace in the region of the lower third of the The shaft furnace becomes one that comes, for example, from a melter gasifier The reducing gas is blown into the shaft furnace and thus into the solid bed. The hot dust-laden reducing gas flows through the solid bed upwards and reduces the iron oxide of the fill wholly or partially to form sponge iron.

The fully or partially reduced iron oxide is caused by between the bottom area of the Discharge devices arranged in the shaft furnace and the area of the gas inlet openings conveyed out of the shaft furnace, whereby the bed column located in the shaft furnace sinking down due to gravity.

Due to its design, a shaft furnace must ensure that it has an even, as complete a reaction as possible, as well as a uniform lowering of the bulk material can be done.

AT PS 387 037 discloses a shaft furnace for the thermal treatment of Feedstocks with gaseous media. Are there for the supply of reducing gas Gas inlet openings provided by an annular apron opposite the in Input materials introduced in the shaft furnace are covered. Between the ring-shaped apron and an annular extension of the casing of the shaft furnace is an annular one Cavity provided so that the introduced reducing gas over the circumference of the The shaft furnace can be distributed to the feed materials.

This design of the gas supply system has serious disadvantages. The inner walls shaft ovens are usually made of refractory material, for example fireclay, brick. Such an annular apron can, however, because it only has its upper circumference is connected to the casing of the shaft furnace, not from individual refractory bricks getting produced. However, this type of gas supply system is monolithic, i.e. from one Manufactured in one piece, basically producible. To do this, however, individual segments of the Shaft furnace jacket together with the attached part of the annular apron each be made from a single piece of refractory material. But this is because of the Size of the segments, and due to their complex geometry hardly to be carried out.

An annular apron made in this way would also be used in the first The loading of the shaft furnace collapses. The side forces from fillings, for example due to process-dependent volume increases, are considerable. Thereby the ring-shaped apron would break away immediately.

DE PS 34 22 185 discloses an arrangement of a carburetor and a Direct reduction shaft furnace. The direct reduction shaft furnace points above its floor star-shaped screw conveyors with which lumpy material from the Shaft furnace is promoted. The inner ends of the screw conveyors are in one conical installation in the middle of the shaft furnace. This is conical installation connected downward with the melter gasifier so that reducing gas from the Melting gasifier can flow through the conical installation in the shaft furnace. Reduction gas is also supplied to the shaft furnace via at least one gas inlet opening supplied, which is formed in a ring apron and the shaft furnace jacket Annulus opens. The same applies to this ring apron as to those in AT PS 387 037, i.e. she would immediately break away to the side and / or because of the abrasive forces on her moving fill be ground. This is all the more true because of the the same height as the ring apron conical installation from the perspective of Filling material represents a reduction in the free cross-section of the shaft furnace. As a result, the laterally effective forces from the bed in the area of conical installation and the ring apron much larger than in other areas of the Shaft furnace. In addition, the fill forms in areas of reduced cross-section prefers caking, agglomerations and bridges. This will make it even Lowering of the bulk material prevented.

From the prior art, for example US Pat. No. 3,816,101 or US Pat. No. 4,046,557, shaft furnaces are known in which a reducing gas is first introduced into the shaft furnace annular cavity is introduced, from which several Gas supply channels in a truncated cone-shaped extension of the Shaft furnace jacket, which extension is filled with the bulk material in the shaft furnace. In a vertical section, the ring-shaped Cavity on a rectangular cross-sectional area, being from the bottom and / or from the inner wall of this annular space, the gas supply ducts opening into the extension of the shaft furnace lead away.

This gas supply system is unsuitable if the reducing gas is evenly above the Scope of the shaft furnace should be distributed. Because the bulk material directly is the number of gas entry points in the shaft furnace and each gas inlet opening thus only as large as the number of gas inlet openings in the bed.

When using a dust-laden reducing gas, dust can accumulate at the mouth of the Store the gas supply ducts in the shaft furnace and check the gas permeability of the Reduce the fill, which deposits more dust, etc. and ultimately the Gas supply channels blocked. Additional dust can also accumulate on the bottom of the annulus drop. In extreme cases, even lumpy material can flow from the fill into the annulus reach. The removal of the solids deposited in the gas supply system is not possible without taking the shaft furnace out of operation and emptying it. By clogged gas supply channels lead to gas flow disturbances in the fill to an uneven reduction of the bulk material and a reduction in the Product quality.

The object of the invention is therefore a shaft furnace, in particular a To provide direct reduction shaft furnace, the gas supply system is designed so that the disadvantages known from the prior art are avoided.

in particular, this gas supply system should be simple from conventional Refractory material can be produced and sufficient mechanical stability to the have lateral forces from the bed. Dust-laden reducing gas should evenly around the circumference of the shaft furnace and therefore also in the Distribute bulk and avoid clogging of gas supply channels become.

This object is achieved according to the invention by the features of claim 1. The shaft contour points in the area of Gas inlets a diameter expansion on and the wall of the shaft furnace is designed such that between the in the area of this diameter expansion arranged gas inlet openings and the bed an annular cavity is that which remains free of pouring.

With the design of the gas supply system according to the invention, it is possible for the first time to supply gas to a shaft furnace evenly distributed over its circumference without one mechanically unstable and hardly producible from conventional refractory bricks Ring apron must be provided.

According to an advantageous feature, there are a number in the area of diameter expansion of means - for dividing the annular cavity into separate sections - Arranged and attached to or in the wall of the shaft furnace.

Of these means for dividing the annular cavity, for example 2 to 16, however, preferably 4 to 8 are spaced approximately equally apart from one another arranged in the area of the diameter extension, so that the annular cavity in as many sections is divided.

These means for dividing the cavity are preferably vertical arranged sheets and / or plates formed, which are dimensioned so that each such means the vertical cross section of the cavity at least in its entirety interspersed.

According to a further advantageous embodiment, in addition to the means for Dividing the cavity further means - for dividing the annular space into each other separate sections arranged in the annulus, each of the separate Sections of gas can be supplied independently of one another from outside the shaft furnace is.

The division of the annular cavity into separate sections together with the division of the annulus into separate sections proves to be advantageous because it avoids or reduces the risk that the Reduction gas - in the event of temporary gas flow disturbances in the fill - the path of the least Resistance increases and thereby partial areas of the bed are reinforced by reducing gas are flowed through and other partial areas of reducing gas are "undersupplied".

Preferably, the means for dividing the annular space and the means for Dividing the cavity arranged such that a portion of the annulus one Number of sections of the cavity is assigned, causing gas over the respective Section of the corresponding section (s) can be fed.

It is particularly preferred that the number of means for dividing the annular space is the same as the number of means for dividing the cavity and a section is assigned to a section.

By dividing the annular space and the cavity by suitable means, such as Refractory material, sheets, etc., are created in closed areas, which are individual and can be targeted with gas quantities. For example, it is possible, despite local different bulk permeability the same amount of gas in each area of the Bring in the bulk. However, it is also possible if this is the process control requires deliberately introducing different amounts of gas per area into the bed.

According to a further advantageous embodiment of the shaft furnace according to the invention the vertical cross section of a section of the annulus from the location of the gas supply designed to taper in the circumferential direction to the respective section ends.

As a result, the speed of the dust-laden gas from the location of the Gas supply to the end of each section does not decrease or does not decrease as much as this would be the case with a constant cross-section of the annular space. As a result, the gas velocity remains sufficiently high at all locations in the annulus to Avoid dust deposits in the annulus.

According to a further advantageous embodiment, a number of Gas supply channels each one that can be operated from outside the shaft furnace Associated cleaning device, by means of which caking from the Gas supply channels or the gas supply channels in the gas flow direction upstream annulus is cleanable.

Process malfunctions can also lead to deposits / caking in the annular space or Lead gas supply channels. The cleaning device (s) can be used for cleaning of these deposits occur. It is particularly advantageous that the Enlargement formed a sufficient volume for the cavity Includes the detached material while otherwise only providing one Blockage of the gas supply channels would result. It is therefore a complex Emptying the shaft or removing material from the outside is avoided.

In the simplest case, a cleaning device is expediently used as Punching device formed, the poking device the outer wall of the Annulus essentially in the extension of one gas supply channel interspersed.

According to a preferred embodiment, the diameter expansion forms a truncated cone-shaped surface, the generatrix of which forms an angle with the horizontal includes, which is smaller than the angle of repose of the goods in the shaft furnace.

This forms a part of the truncated cone-shaped surface vertical inner wall of the shaft furnace and ring-shaped bounded by the fill Cavity in which the gas supplied through the gas inlet openings can distribute evenly. The natural angle of repose is closed at the angle of repose understand the generatrix of the lateral surface of a pouring cone with the horizontal includes.

The angle which the generatrix of the lateral surface with the Includes horizontal, 0 to 25 °, with the diameter widening from the top to the top expanded below. The angle of repose of lumpy iron sponge, ore pellets or lumpy Ore is around 35 to 40 °. So the difference between these two angles is big enough to create an annulus in which the reducing gas is optimally distributed can.

The angle which the generatrix of the lateral surface with the is particularly preferably Includes horizontal, 0 °. In this version, the distance between the bed and Shell surface, or the gas inlet openings arranged in the shell surface so large that the risk that dusty or lumpy material from the bed in one of the Gas supply channels can reach is minimized.

The gas supply system also has excellent mechanical stability since the Dimensions of the gas supply channels that penetrate the wall of the shaft furnace, so can be kept low that the gas inlet openings, or that of the Gas supply channels and the refractory material surrounding the gas supply channels formed gas supply system withstand the lateral forces acting from the bed can.

The gas supply system is also easily made of conventional refractory material, for example firebrick, can be produced because each part of the gas supply system underlying parts is supported. They are not facilities such as one Ring apron provided only over an upper edge with the wall of the shaft furnace would be connected.

According to an advantageous embodiment, the gas supply channels have an im essentially rectangular cross-section and taper from bottom to top executed, the inner edges of the gas supply channels are rounded. This is ensured that gas supply channels, in which despite the inside of the shaft furnace formed material-free annular cavity a material jam occurs by itself, i.e. clean again with the downward movement of the goods in the shaft furnace.

According to a further advantageous embodiment, the transition between the annular space which surrounds the shaft furnace on the outside in a ring, and the gas supply channels at an angle sloping downwards. As a result, dusty material can form from the Do not accumulate reducing gas in the annulus and also material from the bed due to process-related disturbances in the annulus, cannot remain there. Rather, such material is due to gravity by the downward movement expanding gas inlet openings are returned to the shaft furnace.

Fig. 1:

Gesamtdarstellung des Schachtofens

Fig. 2:

Durchmessererweiterung des Schachtofens mit Gaszuführungskanal und Ringraum

Fig. 3:

Schnitt A-A aus Fig. 1

Fig. 4:

Schnitt B-B aus Fig. 2

Fig. 5:

Schnitt C-C aus Fig. 2

The shaft furnace according to the invention is explained in more detail below by the drawings in FIGS. 1 to 5.

Fig. 1:

Overall view of the shaft furnace

Fig. 2:

Expansion of the shaft furnace diameter with gas supply channel and annulus

Fig. 3:

Section AA from FIG. 1

Fig. 4:

Section BB from FIG. 2

Fig. 5:

Section CC from FIG. 2

1 shows the shaft furnace 1 according to the invention with a bed of lumpy material 2, which can be applied to the shaft furnace 1 from above (feed device not shown). in the The area of the lower third of the shaft furnace 1 is a plurality of gas inlet openings 3 arranged in one plane. Through these gas inlet openings 3, a reducing gas is in the Blown in fill 2. Above the bottom of the shaft furnace 1 are screw conveyors 4 arranged, through which the lumpy material is discharged from the shaft furnace 1.

In Fig. 2 is one of the gas inlet openings 3 with the shaft furnace 1 surrounding the outside Annulus 5 and one of the gas supply channels 6, which the gas inlet openings with the Connect annulus 5, shown. The diameter extension 7 of the shaft contour is as horizontal recess in the jacket of the shaft furnace 1, so that between Gas inlet openings 3 and bed 2, an annular cavity 8 is formed. In this cavity 8 can be through the gas supply channels 6 and Optimally distribute the gas inlet openings 3 supplied reducing gas. 2 are also a Means 11 for dividing the cavity, and a means 12 for dividing the annular space 5, here each formed as a vertically arranged sheet, shown in dashed lines. The outer jacket of the annular space 5 passes through a cleaning opening 13 in such a way that the Central axis of the cleaning opening 13 with the central axis of the gas supply channel 6 coincides. The cleaning opening 13 is sealingly closable on the outside. If this is necessary, for example by means of a rod 14 (straight or curved) Gas supply channel 6 and part of the annular space 5 are cleaned of deposits.

Fig. 3 shows a section through A-A of Fig. 1, with the viewing direction perpendicular is selected from below in the direction of one of the gas supply channels 6. The inner edges 9 of the Gas supply channels 6 are rounded and the gas supply channels 6 are upwards executed rejuvenating. This ensures that dusty material from the Reducing gas is not deposited in the gas supply channels 6, or that the Gas supply channels 6 in the event of a material jam with the downward movement of the lumpy Clean good again by yourself.

Fig. 4 shows a section through B-B of Fig. 2, viewed from the inside of the shaft. The Gas supply channels 6 expand from top to bottom and the transitions 10 from that Annulus 5 to the gas supply channels 6 are designed to slope downwards. This is also intended to ensure that dust-like material from the reducing gas is not in deposits in the annular space 5, but together with the reducing gas in the shaft furnace 1 is entered.

Fig. 5 shows a section through C-C of Fig. 2, the annular space 5 with - in The circumferential direction decreases from the location of the gas supply 15 to the means 12 for dividing the annular space 5 Cross section is shown.

The invention is not limited to that shown in the drawings in FIGS. 1 to 5 Embodiment, but also includes all known to those skilled in the art Execution of the invention can be used.

For example, the sheets or plates 11 are not of the shape shown in FIG. 2 and Size limited, but can, depending on the material and process-related Requirements, for example, also have contours similar to rectangles or segments of a circle and also have smaller dimensions, so that they are not as far as shown in FIG protrude into the bed 2.

The annular space 5 can, as shown in the exemplary embodiments, structurally with the shaft be connected, but it is also possible that the annular space from an annular pipeline is formed, which concentrically surrounds the shaft - spaced apart from it. The The connection between the ring pipeline and the gas supply channels then takes place via downward sloping, widening stub lines. This brings additional benefits to the constructive design of the reduction shaft, especially the refractory construction, as well as improved accessibility of the annulus for the purpose of cleaning.

It is also possible that the cross-sectional reduction of the sections of the annular space is not only - as shown in Fig. 5 - designed as a reduction in the horizontal diameter is, but - alternatively or additionally - as a reduction in the vertical diameter of the annulus or - in the case of an annular pipeline - as a conical constriction.

Claims (14)

1. System comprising a shaft furnace (1), in particular direct-reduction shaft furnace, with a charge composed of fragmentary material (2), in particular fragmentary material containing iron oxide and/or sponge iron, the said material being capable of being fed into the shaft furnace (1) from above, and with, arranged in one plane, a multiplicity of gas-inlet orifices (3) for a reduction gas in the region of the lower third of the shaft furnace (1), the shaft furnace (1) being surrounded externally by an annular space (5) which is connected to the gas-inlet orifices (3) downwards by means of gas supply ducts (6), where the shaft contour has a diametral widening (7) in the region of the gas-inlet orifices (3), characterized in that an annular cavity (8), which remains free from charge, is formed between the gas-inlet orifices (3) arranged in the region of this diametral widening (7) and the charge (2).
2. System according to Claim 1, characterized in that a number of means (11) for dividing the cavity (8) into sections separated from one another are arranged in the region of the diametral widening (7) of the shaft furnace (1) and are fastened to or in the wall of the shaft furnace.
3. System according to Claim 2, characterized in that, in the shaft furnace (1) , 2 to 16, preferably 4 to 8 means (11) for dividing the cavity (8) are arranged in the region of the diametral widening (7) essentially at a uniform distance from one another.
4. System according to one of Claims 2 or 3, characterized in that the means (11) for dividing the cavity (8) of the shaft furnace (1) are formed by vertically arranged metal sheets and/or plates.
5. System according to one of Claims 2 to 4, characterized in that, in addition to the means (11) for dividing the cavity (8) of the shaft furnace (1), further means (12) for dividing the annular space (5) of the shaft furnace (1) into portions separated from one another are arranged in the annular space (5), gas being capable of being supplied (15) from outside the shaft furnace (1), in each case independently of one another, to each of the portions separated from one another.
6. System according to Claim 5, characterized in that the means (12) for dividing the annular space (5) of the shaft furnace (1) and the means (11) for dividing the cavity (8) of the shaft furnace (1) are arranged in such a way that, in each case, a portion of the annular space (5) is assigned to a number of sections of the cavity (8), with the result that gas can be supplied via the respective portion to the section or sections corresponding to it.
7. System according to Claim 6, characterized in that the number of means (12) for dividing the annular space (5) of the shaft furnace (1) is equal to the number of means (11) for dividing the cavity (8) and a portion is assigned in each case to one section.
8. System according to one of Claims 5 to 7, characterized in that the vertical cross section of each portion of the annular space (5) of the shaft furnace (1) is designed to taper in the circumferential direction from the location of gas supply (15) to the respective portion ends (12).
9. System according to one of Claims 1 to 8, characterized in that a number of gas supply ducts (6) of the shaft furnace (1) are assigned in each case a cleaning device (13, 14) which is capable of being operated from outside the shaft furnace (1) and by means of which caked-on accumulations can be cleaned off from the gas supply ducts (6) or from the annular space (5) preceding the gas supply ducts (6) in the gas flow direction.
10. System according to Claim 9, characterized in that, in each case, a cleaning device (13, 14) of the shaft furnace (1) is designed as a poker device, the poker device passing through the outer wall of the annular space (5) essentially in each case in the extension of a gas supply duct (6).
11. System according to one of Claims 1 to 10, characterized in that the diametral widening (7) of the shaft furnace (1) widens from the top downwards, and in that the generatrix of the frustoconical generated surface forms with the horizontal an angle of 0° to 25°.
12. System according to Claim 11, characterized in that the generatrix of the frustoconical generated surface of the shaft furnace (1) forms with the horizontal an angle of 0°.
13. System according to one of Claims 1 to 12, the gas supply ducts (6) of the shaft furnace (1) having an essentially rectangular cross section, characterized in that the gas supply ducts (6) are designed to taper from the bottom upwards, and in that the inner edges of the gas supply ducts (6) are rounded.
14. System according to Claim 13, characterized in that the transitions (10) from the annular space (5), which surrounds the shaft furnace (1) externally, to the gas supply ducts (6) are designed to descend obliquely downwards.

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