The present invention refers to a device for selectively dispensing limestone for regenerating ovens. The present invention further refers to a process for selectively loading limestone in a regenerating oven using such device.

As known, parallel-flow regenerating ovens for manufacturing lime from limestone are composed of two vats, which are mutually interconnected through a connection channel.

Limestone is loaded in every vat and descends along the pre-heating area, in which regenerative heat exchange occurs in counter-current with fumes, passes the lances, which insert fuel and arrives to the baking/calcining area. From here, it reaches the lime cooling area.

The oven operation allows the alternate combustion in every vat with a combustion cycle which is 8 to 12 minutes long.

During every alternate combustion cycle, fuel is

entered into tne vat under comDustion through the lances, and burns in the combustion air, which ■ is blown into the vat, releasing ^' heat, which is partly absorbed by the limestone calcining. Simultaneously, cooling air is entered at the base of every vat in order to cool the lime. The cooling air of the vat under combustion, together with combustion gases and carbon dioxide released from the limestone when calcining, pass through the transverse interconnected channel, reaching the other vat at a temperature up to 1050° C, in which they are mixed with cooling air at the base and rise, thereby heating the limestone which can be found in the heating area.

•In traditional ovens, however, combustion gases rise along the vat through the limestone by travelling, due to their own physical nature, along the short trajectory, namely the one flanking the internal wall of each vat, making the heating of crosses limestone irregular.

Object of the present invention is solving the above prior art problems, by providing a device for selectively dispensing limestone for regenerating ovens which allows loading each vat by dividing the limestone depending on its size or granulometric curve, in such a way as to create a lower-resistance path defined for the combustion fumes circuit.

Another object of the present invention is providing

a process for selectively loading limestone in a regenerating oven using the selective . dispensing device according to the present invention.

The above and other objects and advantages of the invention, as will, appear from the following description,, are reached with a device for selectively dispensing limestone for regenerating ovens as claimed in claim 1.

Moreover, the above and other objects and advantages of the invention are reached with a process for selectively loading limestone in a regenerating oven using the selective dispensing device as claimed in claim 8.

Preferred embodiments and non-trivial variations of the present invention are the subject matter of the dependent claims .

The present invention will be better described by some preferred embodiments thereof, provided as a non- limiting example, with reference to the enclosed drawings, in which:

- FIG. Ia and Ib show various longitudinal sections of vats of a regenerating oven schematically showing the modes for filling with limestone using the selective dispensing device according to the present invention;

- FIG. 2 shows a front sectional view of a regenerating oven equipped with the device for selectively dispensing limestone according to the present invention;

- FIG. 3a and 3b show a side ^' sectional view of a vat of the oven in FIG. 2 in different operating positions; and

- FIG. 4 shows ^' another side sectional view of the vat of FIG. 3a and 3b along the sectional plan A-A.

With reference to FIG. Ia and Ib, and in particular to representations a, b, c, d which show the loading modes with limestone respectively of a first vat 5a with a top view, of the first vat 5a with side sectional view, of a second vat 5b with top view, of the second vat 5b with side sectional view, it is possible to note that the scope of the selective dispensing device 1 according to the present invention is allowing to load with limestone each vat of a regenerating oven creating a lower-resistance path to descending/ascending flow of combustion fumes towards the top of each vat, advantageously arranging the limestone with greater sizes 3 next to the external walls 7a, 7b (as shown in representations a, b, c, d of FIG. Ib) and limestone with smaller sizes 4 next to the internal walls 8a, 8b (as shown in representations a, b, c, d of FIG. Ia) of each vat 5a, 5b. In fact, since limestone with greater sizes has interstices with bigger sizes among the granules once having been loaded in the vat with respect to existing sizes among granules with smaller sizes, which are arranged more compactly one with respect to the others, fumes will find a lower-resistance path next to

the external wall, consequently travelling, when rising towards the limestone, along a longer path, consequently releasing a greater amount of heat, and in a more homogeneous way.

In order to obtain the above described results, and with reference to FIG. 2, it is possible to provide each vat 5a, 5b, next to its own hood, with a selective dispensing device 1 for limestone according to the present invention, as will be described below.

To obtain a more efficient use of the selective dispensing device 1 according to the present invention, it would be preferable to previously provide an operation for separating limestone in order to divide it depending on granule sizes into at least one batch with greater sizes and one batch with smaller sizes. The oven, and in particular each vat 5a, 5b, is then loaded through the top 6a, 6b of each vat 5a, 5b by a loading system (not shown) comprising at least one first line for loading limestone with greater sizes and at least one second line for loading limestone with smaller sizes. Preferably, loading occurs in each vat 5a, 5b through an alternate supply from the first loading line and the second loading line.

With reference now further to FIG. 3a, 3b and 4, it is possible to note that the selective dispensing device 1 according to the present invention comprises at least one

mobile bulkhead 11, connected to a drive shaft 13 rotating around a rotation axis X, such rotation being driven by an actuator system, mentioned below; in particular, the mobile bulkhead 11 can rotate around the rotation axis X in order to be alternatively inclined by a first angle α and by a second angle β with respect to a reference plane Z (inclined positions are shown dashed in FIG. 2), such plane being preferably vertical and passing by the rotation axis X.

In order to obtain the selective loading of limestone in each vat 5a, 5b, it is therefore enough to provide that, when the vat 5a, 5b is supplied by the first loading line,- the actuator system takes care of inclining the mobile bulkhead 11 by the first angle α (as shown in FIG. 3a) in such a way as to address and arrange the limestone with greater sizes against the external wall 7a, 7b of the vat 5a, 5b itself; when instead the vat 5a, 5b is supplied by the second loading line, the actuator system takes care of inclining the mobile bulkhead 11 by the second angle β (as shown in FIG. 3b) in such a way as to address and arrange the limestone with smaller sizes against the internal wall 8a, 8b of the vat 5a, 5b itself.

Obviously, the absolute values of the first and second angle α, β can be adjusted depending on limestone sizes granulometry and their respective rest angle, in

such a way as to guarantee the most efficient selective loading according to the present invention for each vat 5a, 5b.

Always with reference to FIG. 3a and 3b, it is possible to note that the actuator system comprises an actuating piston 14, such as a double-effect cylinder of the pneumatic, hydraulic or oleo-dynamic type, connected to a bracket 15 of the drive shaft 13 substantially perpendicular to the rotation axis X; in such a way, when the actuating piston 14 cylinder performs its stroke along a direction, the mobile bulkhead 11 is inclined by the first angle α, while when the actuating piston 14 cylinder performs its stroke along the opposite direction, the mobile bulkhead 11 is inclined by the second angle β. The actuator system can obviously further comprise drive and control means of the actuating piston 14 which, depending on which loading line is supplying each vat, impose the related correct inclination to the mobile bulkhead 11.

It would be preferable, due to obvious actuator system managing and operating reasons, that the absolute values of the first and the second angle were the same, namely | α |=| β |: in such case, the mobile bulkhead 11 will be alternatively inclined by an angle +α and -α with respect to the reference plane Z.

The previous description has been made with reference

to the Figures considering ^" the reference plane Z as substantially vertical: it is however clear that the above described statements can be wholly applied also in case a substantially horizontal reference plane is taken into account, though this latter one is technically less practical to realise, due to reduced spaces available inside the vats 5a, 5b for placing an horizontal mobile bulkhead.

The present invention further refers to a process for selectively loading limestone in a regenerating oven using the selective dispensing device according to the present invention; in particular, the inventive process comprises the steps of:

- separating limestone in order to divide it, depending on granules sizes, into at least one batch with greater sizes and one batch with smaller sizes;

- inclining the mobile bulkhead 11 by the first angle α with respect to the reference plane Z through the actuator system;

- supplying a top 6a, 6b of the vat 5a, 5b through the first line for loading limestone with greater sizes;

- inclining the mobile bulkhead 11 by the second angle β with respect to the reference plane Z through the actuator system;

- supplying the top 6a, 6b of the vat 5a, 5b through the

second line for loading limestone with smaller sizes;

- repeating the previous steps till the vats 5a, 5b have been suitably filled with limestone.