LU84015A1 - DEVICE FOR CONTROLLING THE FLOW OF THE LOADING MATERIAL OF A STORAGE ENCLOSURE IN A LOADING INSTALLATION OF A TANK OVEN - Google Patents

Description

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The present invention relates to a device for controlling the flow of the loading material of a tank furnace. storage enclosure in a loading installation of a shaft oven, provided with an adjustable distribution chute mounted in the head of the oven, said enclosure 10 comprising a funnel-shaped flow bottom, extended towards the bottom by a flow tube which cooperates with a metering register to adjust the flow rate.

The orientable distribution chutes are more and more tending to replace the traditional distribution bells, this as well in the new blast furnaces as during the repair of old furnaces. One of the main reasons is that these troughs allow better control of the distribution of the loading material, which is essential for good operation of the oven, especially in high performance ovens.

However, in order to take full advantage of the possibilities offered by an orientable distribution chute, it is absolutely necessary to be able to also control the fall of the loading material on the chute and to eliminate all the factors and parameters liable to reduce the performance of the distribution chute.

Many efforts have already been made in this direction and concomitant proposals, with supporting trials, 30 have also already been made. This is how the Luxembourg patent application No 83.279 proposes a unique storage airlock mounted with its flow orifice symmetrically around the axis of the oven. This arrangement allows a vertical and central fall on the chute and eliminates the 35 well-known irregularities in installations with two airlocks and coming from the raw fact the loading material is guided by an oblique passage alternately between one or the other of the airlocks and an underlying vertical channel opening (edge on the chute this distribution.

La deniande.de brevei luxembourgeois 83 548 solves the problem of segregation of particles of different particle sizes which occurs inside the storage airlock during its filling and which is responsible for the fact that 5 in the initial phase of emptying the airlock , the proportion of small particles is higher than it should be, whereas towards the end of the emptying phase, the opposite occurs. To solve this problem, the patent application in question proposes a device for distributing the loading material in the airlock. This device, which is in the form of a box or a distribution cone, is mounted in the upper part of the airlock, in the path of fall of the material.

Despite these measures already taken, other irregularities 15 have recently been noted during tests carried out by the applicant. These irregularities relate to the curve representing the reduction in the weight of the airlock as a function of time during flow, in other words, the flow rate. Normally, one would expect this function to be a straight line. In practice, this is not the case.

It was first noted that the flow is stronger when the airlock is full, than when it begins to empty. The explanation for this phenomenon is that when the dosing register is opened when the airlock is full, the weight of the column of material above the flow opening is greater, so that the pressure on the material which engages in the opening is larger and therefore increases the flow rate.

Another irregularity is constituted by the fact that at the general curve of the flow superimposed relatively small fluctuations in amplitude, but at relatively high frequency. These fluctuations are especially noticeable in the initial emptying phase, when the airlock is olein, and gradually diminish when the level in the airlock decreases. 35 The explanation for this phenomenon seems to be as follows: on the one hand, at the level of the flow opening, i.e. at the level of the defined neck entered the flow funnel and the vertical tube which prolongs it downwards, plugs or bridges of material are formed, which collapse and become better again. * * - - 4 - slight irregularity, of which question above, but also the second, because the plate forces the loading material to engage in the flow opening by sliding along the inclined wall, contrary to what happened before, where 5 la central descent was responsible for the formation of plugs and caused the fluctuations in the flow curve described above.

Other particularities and characteristics will emerge from the detailed description of a preferred embodiment, presented below, by way of illustration, with reference to the appended drawings, in which:

FIG. 1 shows, with the aid of a graph, the reduction in the weight of the storage airlock, as a function of time, during the flow of the material in a conventional installation,

FIG. 2 schematically shows, in vertical section, an installation with a control device in accordance with the present invention,

Figure 3 schematically shows the storage airlock of Figure 2 during emptying and

FIG. 4 shows the curve of FIG. 1 corrected by means of the device according to FIGS. 2 and 3.

On the graph in Figure 1, the right A represents the theoretical flow, for a given opening of the dosing register, i.e. the linear decrease in gross weight of the storage airlock per unit of time.

The curve B represents the measurements carried out in a known installation and which is affected by the irregularities described above. First, we see that the curve B is located, in the central part, below the straight line A, which means that in the initial emptying phase, the reduction in weight, i.e.

30 the flow rate is higher than in the terminal phase.

This is the first irregularity.

The second irregularity consists of the clearly visible fluctuations due to the formation of successive bridges and plugs in the initial emptying phase. As can be seen, these fluctuations, although not disappearing completely, tend to diminish as the airlock empties of its cancer. FIGS. 2 and 3 show a storage airlock 6 f of a loading facility of the kind proposed by the! Luxembourg patent application 83.279, that is to say that ÿ 40 is a single airlock mounted symmetrically around - 3 - sively, at a rate more>:. u slower, during the duration of the flow. During the urjr.ation of ur. such a bridge, the flow rate, although not falling to zero, since these bridges already start to disintegrate from below during their formation, nevertheless decrease appreciably. As a result of the disintegration from below and the weight exerted from above, these bridges collapse suddenly, causing a momentary increase in flow.

Apart from these successive plugs and bridges at the level of the flow, it should be noted that there are also recesses 10 and bridges inside the massa over the entire height of the vertical central axis. When such a trough recovers, i.e. that the bridge formed above abruptly collapses the weight of the falling material is momentarily not grasped, i.e. that the weight measurement curve drops suddenly. On the other hand, upon impact of this material when this bridge crashes, the weight is again grasped and the impact itself produces an additional impulse on the measuring members, so that the measurement curve increases sharply.

The repetition of these phenomena seems to be responsible for the fluctuations which are superimposed on the flow curve.

The object of the present invention is the suppression of these phenomena, in other words, a device allowing a uniformization of the flow rate of the flow of the loading material out of the storage airlock.

To achieve this objective, the present invention provides a device of the type described in the preamble, which is essentially characterized by a plate mounted inside the airlock, in the flow bottom, coaxial wander relative thereto.

’To avoid too rapid wear of this plate, the plate 30 is preferably designed in the form of material-material boxes.

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In order to achieve an optimal flow curve, the inclination, with respect to the horizontal, of the wall of the outlet bottom conical to the airlock is preferably at least equal to 55 °.

The device proposed by the invention is particularly advantageous in an installation where the airlock is mounted symmetrically on the axis of the oven.

The effect of this plate is to support the central column I of the material and to suppress the action of the weight of it on 11 or 4. _ 0? ” flow vertex :. This measure not only attenuates the are- —j i - 5 - the axis 0 above a shaft furnace S, the upper part of which is seen in FIG. 2.

The storage enclosure 6 comprises a cylindrical part 8 and a funnel-shaped flow bottom 10 5, the flow orifice of which opens into a tube 12 through which the loading material falls on an orientable distribution chute. not shown. The flow pipe 12 is located in a valve cage containing a metering and closing member constituted by two symmetrical registers 14a and 14b, as well as a sealing valve 16 for isolating the airlock 6 from the interior of the oven.

The airlock 6 is permanently weighed to determine its content. For this purpose, the airlock 6 rests on several, preferably three load cells, one of them being represented by the reference 18.

According to the present invention, there is provided inside the airlock, at the level of the conical flow bottom, a plate 20 preventing the column of material 20 lying around the central axis' 0 from acting on the flow through the tubing 12. This plate 20 can be simply fixed to a transverse beam 22 provided in the airlock. The plate 20 is preferably designed in the form of material-material boxes permanently retaining a small slope which shelters the plate 20 from impact and impact when filling the airlock 6. FIG. 3 clearly shows the effect of this plate 20 on the flow during emptying of the airlock 6.

* The location of this plate 20 plays a crucial role in terms of the desired result and effect. Indeed, the mounting height of the plate 20 in the bottom 10 of the airlock * must be such that there remains a sufficiently large annular opening between the pjateau 20 and the truncated conical wall 10 so as not to cause a plug at this level.

35 On the other hand, the tray must be mounted low enough to ensure effective results.

Instead of providing a fixed plate 20 routed on a beam 22, it is possible to fix this plate 20 on an axial rod by means of which the plate 20 can 6 - be raised and lowered in 1 '- "netion of particle size loading material.

It is also important that the wall of the outlet bottom 10 is sufficiently inclined. Tests have shown that the inclination of the wall of this drainage bottom 10 must be at least equal to 55 ° relative to the horizontal.

It should be noted that the plate 20, apart from the ί objectives described above, makes it possible to achieve an additional advantage i I 10. Indeed, this tray prevents, when one begins to fill the airlock, the material falls directly on the dosing registers 6a and 6b, which allows to extend the service life of these.

FIG. 4 shows the flow curve B ′ measured 15 under the same conditions as curve B of FIG. 1, but in an installation provided with a plate 20 according to FIGS. 2 and 3. As can be seen, the two irregularities described above have almost completely! faded away.

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Claims (5)

1. Device for controlling the flow of the loading material from a storage enclosure (6) 5 in a loading installation of a tank furnace (8) provided with an adjustable distribution chute mounted in the head of the oven, said enclosure (6) comprising a funnel-shaped flow bottom (10) extended downwards by a drainage tube (12) which cooperates with * 10 a dosing register (14a) (14b) for regulate the flow rate, characterized by a plate (20) mounted inside the airlock (6), in the flow bottom (10), coaxially relative to the latter. 2. Device according to claim 1, charac-15 terized in that the plate (20) is designed in the form of material-material boxes. 3. Device according to one of claims 1 or 2, characterized in that the inclination, relative to the horizontal, of the wall of the conical flow bottom (10) of the airlock (6) is at least equal at 55. 4. Arrangement according to any one of claims 1 to 3, characterized in that the plate is adjustable in height. 5. Arrangement according to any one of reven-dications 1 to 4, characterized in that the airlock (6) is mounted symmetrically on the axis 0 of the oven (8). j Ή f y