EP0516613B1 - Plant comprising a shaft, in particular a reduction shaft furnace - Google Patents

Description

The invention relates to a system according to the preamble of claim 1.

It is known from DE-31 41 280 A and DE-38 34 969 A to feed the bulk material to the shaft via a loading device arranged in the upper end part of the shaft. The loading device is formed by a plurality of pipes rigidly arranged with respect to the shaft, through which the bulk material enters the shaft to form a plurality of bulk material cones, the respective tips of which are always at the same height at the mouth of the associated pipe. The continuous feeding of the bulk material offers the advantage of constant temperature in the upper end region of the shaft, which is not the case when the bulk material is introduced discontinuously, for example in a blast furnace with a charging device designed as a rotary chute, because it is batch-wise and generally cold bulk material, there is a sudden drop in gas temperature.

However, a disadvantage of the known continuous loading devices is that the fine-grain portion of the bulk material of the bulk material is segregated on the bulk material cone, since the coarse-grain portion rolls further on the surface of the bulk material cone than the fine-particle bulk material. This leads to an uneven gasification of the bulk material and, in the case of direct reduction of iron ore, to an unequal degree of reduction, this inequality being exacerbated by the fact that the gases have a higher temperature at points of a higher gasification rate.

In a so-called V-fill (known from DE-31 41 280 A), due to the separation, the coarser particles of the feed material get into the middle, the finer particles remain at the edge. This pushes the gas flow very strongly towards the center. With a so-called M-fill (known from DE-38 34 969 A) or A-fill, the coarser particles run to the edge, the finer ones remain more in the middle. The gas flow is again pushed to the edge, because firstly the specific resistance of a coarse-grained bed is lower and secondly the path to the bed surface is shorter.

In the reduction of lump ore, even gas flow and heating in the top part of the shaft is particularly important because the temperature range of the low-temperature grain decay (up to 7500) should be passed through as quickly as possible. Zones with poor gas permeability are warmed up more slowly, which results in greater grain disintegration, which in turn leads to a greater pressure loss due to the smaller gap volume and thus to an even worse gas flow. In the case of gases containing dust in particular, the ore bed can serve as a fixed bed filter and thus hinder the gassing of the peripheral parts.

From DE-1 151 822 B a system is known in which the bulk material is conveyed into the interior of the shaft with a constant feeding speed with the aid of a loading device designed as a conveyor belt, the loading device having a horizontally movable carriage so that the loading material can be moved to different locations Setting the shaft cross section can be introduced. The gas temperatures can be measured by means of a thermocouple, which is arranged on the carriage approximately at the point at which the feed material is thrown off, and depending on the same, the feed speed of the feed device can be regulated in such a way that the material is dispensed at locations of relatively high permeability increased and the material output is reduced via places of relatively low permeability.

A disadvantage here is the relatively complicated loading device, especially for a shaft with high gas temperatures. It is also disadvantageous that the temperature measuring device is moved with the conveyor belt over the cross section of the shaft, so that only the temperature at one point, namely at the discharge point of the load, can be determined. As a result, it is not possible to determine and correct deviations in the temperature distribution over the entire shaft cross section.

From EP-0 261 432 A it is known in a gas passage shaft to control the introduction of bulk material into the shaft by means of a temperature measurement. However, this does not take place continuously, but rather by batchwise charging, which is absolutely necessary according to EP-0 261 432 A, since bulk material in the part of the shaft interior near the axis is to be charged with a different composition than in the radially adjoining part outer area of the shaft interior. Here there is also the risk of damage to the temperature measuring device due to the charging material falling during the charging process, since the temperature measuring device is arranged below the charging device.

FR-1 406 976 A shows a system with a loading device, in which a loading pipe is rotatably mounted at the upper end of the furnace. This feed pipe is angled in the lower section, and it widens towards the lower mouth so that it can cover almost half the diameter of the furnace. Inside, this feed pipe contains a partition and a flap above it, in order to be able to distribute the feed material over one or the other subchannel, i.e. either feed more radially outside or more radially inside the furnace. At the lower end of the rotating feed pipe, three transmitter devices are also provided to record the temperature, pressure and gas composition on different radii (inside, center and outside). These donor devices are installed inside the feed pipe, where the bulk material flow is fed; In addition, a temperature, pressure and gas composition measurement is always carried out at the respective point on the rotating feed pipe.

A generic system in the form of a shaft furnace is known from US-4 178 151 A. A plurality of outlet pipes for the formation of pouring cones is provided within the upper part of the shaft, these pipes being arranged in a stationary manner and at a regular distance from one another and at a distance from the furnace wall. The muzzle pipes are connected to feed pipes that start from a loading funnel. Each muzzle tube is assigned temperature measuring devices in the form of measuring points with thermocouples, which are attached to the furnace wall below the muzzle tubes and are intended to lie within the bulk material during operation. If the temperature rises sharply at a measuring point, the operator is signaled that there is insufficient bulk material in the muzzle pipes in question. Devices for the individual metering of the quantity of bulk material to the individual outlet pipes are not provided. Due to the rigid arrangement of the muzzle pipes, the bulk material cones are always formed in the same places.

The invention aims at avoiding the disadvantages and difficulties described and has as its object to create a system of the type described at the outset, which has a uniform treatment of the bulk material, i.e. ensures uniform gas flow across the entire cross-section of the shaft with little design effort and high operational reliability.

Starting from a system according to the preamble of claim 1, this object is achieved according to the invention by the features of the characterizing part of this claim.

Advantageous embodiments and further developments are specified in the subclaims.

• Fig.1 den Oberteil eines Schachtes eines Direktreduktionsschachtofens zur Direktreduktion von Eisenerz im Längsschnitt;
• Fig.2 einen gemäß der Linie II-II der Fig.1 geführten Schnitt gemäß einer ersten Ausführungsform; und
• die Fig.3, 4 und 5 jeweils weitere Ausführungsformen in zu Fig.l analoger Darstellung.

The invention is explained in more detail below with the aid of several embodiments; show it:

• 1 shows the upper part of a shaft of a direct reduction shaft furnace for the direct reduction of iron ore in longitudinal section;
• 2 shows a section according to line II-II of FIG. 1 according to a first embodiment; and
• 3, 4 and 5 each further embodiments in a representation analogous to Fig.l.

1 designates an upper part of a refractory-lined, essentially cylindrical shaft 2 of a direct reduction shaft furnace, in which lumpy bulk material continuously charged from above, namely iron ore 3, is reduced by means of the reducing gas flowing through the shaft 2 from bottom to top. The reduction gas is introduced in this reduction process in the usual way through feed lines arranged at the lower third of the height of the shaft 2 on its casing 4.

The loading of the shaft with the iron-containing bulk material 3 takes place via a loading device 5 which, according to the embodiment shown in FIG. 1, has a collecting container 6 which is arranged centrally to the shaft 2 and lies above the shaft 2. From the collecting container 6, which is fed continuously or discontinuously from above through a central opening 7, six feed pipes 9 are arranged, which are evenly distributed around the longitudinal axis 8 of the shaft and which open through the ceiling 10 of the shaft 2 into the interior 11 thereof.

At the ends 12 of the feed pipes 9 lying just below the ceiling 10, tubular mouth pieces 13 are articulated, the articulation being such that the mouth pieces 13 can be pivoted in the radial direction as seen from the longitudinal axis 8 of the shaft 2. The upper end 14 of each substantially straight and cylindrical mouthpiece 13 is funnel-shaped to protrude in each of the pivot positions of the mouthpieces 13 over the lower end 12 of the associated feed pipe 9, so that all bulk material 3 sinking through the feed pipes 9 by the subordinate ones Mouthpieces 13 flows and forms a bulk material cone 16 adjoining the lower opening 15, which is also of an enlarged design.

As can be seen from Fig. 1, the tips 17, i.e. the upper ends of the bulk material cone 16, depending on the pivoting position of the mouthpieces 13 closer to or further away from the longitudinal axis 8 of the shaft 2 and to a small extent higher or lower.

To pivot the mouthpieces from the position shown in full lines in Fig. 1 in the position shown in Fig. 1 with dash-dotted lines is used above the ceiling 10 of the shaft 2 and protected in a housing arranged actuating cylinder 18, the piston 19 via a Deflection rollers 20 in the interior 11 of the shaft 2, the rope 21 is fastened to an adjusting wedge 22 which can be raised and lowered with the adjusting cylinder 18. On the adjusting wedge 22 are attached to the mouth pieces 13 and radially inwardly projecting skids 23 which expand upwards in the radial direction towards the longitudinal axis 8.

On the ceiling 10 of the shaft 2, a gas discharge opening 24 is provided on the side of the mouths of the feed pipes 9.

Just above the uppermost layer that can be taken up by the lower openings 15 of the mouth pieces 13, a plurality of temperature measuring devices 25 are provided in a cross-sectional plane Q of the shaft 2, which are preferably designed as thermocouples. These thermocouples 25 are arranged in the interior of steel tubes 26 which extend radially across the cross section of the shaft 2 and in which the electrical connecting lines 27 are also guided. The steel tubes 26 protrude through the jacket 4 of the shaft 2 to the outside. The electrical connecting lines 27, which are led to the outside via the steel pipes 26, are connected to a computing and control unit (not shown), which in turn is coupled to the actuating cylinder 18 for adjusting the position of the mouth pieces 13 in the manner described below.

In the case of a stationary pouring of the bulk material 3 in the interior 11 of the shaft 2, the bulk material is segregated, since the bulk of the bulk material 3 on the bulk material cone 16 rolls further outwards. As a result, the finer bulk material 3 collects in the center of the bulk material cone, i.e. where the bulk material cone 16 has its greatest height and thus the longest gas passage path, so that, in addition to the longest gas passage path, a gas permeability which is lower than the edge zones of a bulk material cone 16 occurs. This causes an uneven gasification and thus an uneven degree of reduction of the ore.

Above the points at which the gas penetrates the bulk material 3 more quickly, the gas emerging from the bulk material 3 has a higher temperature, so that on the basis of the temperature values measured in a cross-sectional plane Q, the duration of the treatment can be concluded from the gas flowing through the bulk material below the temperature measuring device 25. According to the invention, if the measured temperature values deviate from a temperature value to a certain extent, the introduction of the bulk material 3 is changed such that the position of the bulk material cone 16 is displaced, namely in the radial direction according to the embodiment shown in FIGS. 1 and 2 until the temperature values measured in the cross-sectional plane Q are the same or only differ from one another to such an extent that, seen across the cross section of the shaft 2, a conclusion is drawn as to the constancy of the quantity of gas flowing through the bulk material 3 and thus to a uniform treatment of the bulk material 3 by the gas can.

According to the embodiment shown in FIG. 3, in which an operating state is shown in each of the two halves of the picture, the charging device 5 has both a central charging pipe 9 'and charging pipes 9 lying radially at a certain distance therefrom. All loading tubes 9, 9 'are each provided with a telescopic over the loading tube 9, 9' slidable and fixable in different sliding positions mouthpiece 13 ', which makes it possible to bring the outlet openings 15 of the loading device 5 to different heights. As a result, not only do peaks 17 of the bulk material cone 16 lying at different heights result, but also different types of fill, such as an A fill, which is shown in the left half of FIG. 3, or a V fill, which is in the right Image half of Fig. 3 is shown.

The embodiment shown in FIG. 4 also enables a V-bed and an A-bed to be varied, the illustration being analogous to that of FIG. 3. In the interior of the loading device 5, a slide 28 is provided in the vertical direction, which can be shifted in different positions and can be fixed in these positions and is designed as a cylinder. In the raised position, the radially outer mouth pieces 13 äußeren, which are formed in one piece with the loading pipes 9, 9˝ , closes and, in the lowered position, blocks the centrally arranged mouthpiece 13˝ with the aid of a conical insert 29 arranged centrally in the interior thereof.

According to the embodiment shown in Fig. 5, which is similar to the embodiment shown in Figs. 1 and 2, the pivotability of the mouthpieces 13 is such that a pure A-bed can be achieved if the mouthpieces 13 inwards to Longitudinal axis 8 of the shaft 2 are pivoted.

Claims (10)

1. Plant, in particular a reduction shaft furnace for the direct reduction of metallic ores (3), comprising a shaft (2) which, in its upper end region, includes gas exhaust means (at 24), charging means (5) for continuously charging bulk material (3) and having a plurality of stationary charging tubes (9; 9') to which mouth pieces (13; 13'; 13") are associated within the upper end region of the shaft (2) for the formation of conical piles (16) located in the shaft (2), as well as several temperature measuring means (25) fixedly mounted externally of the charging tubes (9, 9') in a cross-sectional plane (Q) on various diameter lines in the upper end region of the shaft (2), characterised in that the temperature measuring means (25) are provided above the bulk material (3) for measuring the temperature of the gas emerging from the bulk material (3) on a plurality of sites distributed over the free cross section of the shaft (2) at various distances from the shaft center, and that for a temperature-dependent control of the introduction of the bulk material, the mouth pieces (13; 13'; 13") are either

   - displaceable in the radial direction relative to the shaft cross section by actuation means (18, 22) (Figs. 1, 5), or

   - displaceable in terms of height by actuation means (Fig. 3), or

   - selectively lockable by actuation means (Fig. 4).
2. Plant according to claim 1, characterised in that the tubular mouth piece (13') is designed as a telescopic tube. (Fig. 3).
3. Plant according to claim 1 or 2, characterised in that the tubular mouth pieces (13) are designed as pivotable extensions of the stationary charging tubes (9).
4. Plant according to any one of claims 1 to 3, characterised in that the mouth pieces (13, 13', 13") are arranged radially symmetrically with respect to the shaft cross section.
5. Plant according to claim 4, characterised in that a tubular mouth piece (13', 13") is arranged centrically with respect to the shaft cross section (Figs. 3, 4).
6. Plant according to claim 5, characterised in that tubular mouth pieces (9) radially directed with respect to the shaft cross section depart from the centric charging tube (9') and a slide (28) is provided in the interior of the centric charging tube, which selectively closes one or several of the radially outer mouth pieces (13") arranged at the charging tubes (9), or the centric mouth piece (13"), and which is displaceable by actuation means (Fig. 4).
7. Plant according to any one of claims 1 to 6, charcterised in that the temperature measuring means (25) are arranged on carriers (26) spanning the shaft interior (11) in its region comprising the charging arrangement (5).
8. Plant according to claim 7, characterised in that the carriers are comprised by steel tubes (26) and that the temperature measuring means (25) as well as the measuring lines (27) leading to the temperature measuring means (25) are arranged within the steel tubes (26).
9. Plant according to any one of claims 1 to 8, characterised in that the temperature measuring means (25) are arranged between the mouth pieces (13, 13', 13").
10. Plant according to any one of claims 1 to 9, characterised in that the temperature measuring means (25) are coupled with a computer and control unit, which in turn is coupled with the actuation means (18 to 23) for displacing at least one of the mouth pieces (13, 13') (Figs. 1, 3, 5) or for displacing the slide (28) between the central mouth piece (13") and the radially outer mouth pieces (13") (Fig. 4).

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