ITVR20100241A1 - BASIN OVEN FOR MATERIAL FUSION - Google Patents

Description

DESCRIPTION

BASIN FURNACE FOR MATERIAL MELTING

DESCRIPTION

The present invention relates to a basin furnace for melting material, of the type normally used for the subsequent production of materials such as glass, glass wool, rock wool, frits, etc ...

The basin furnaces are furnaces which, as their name indicates, have a melting chamber at the bottom consisting of a containment basin for the molten material. In particular, these are furnaces for continuous production, since in the basin it is possible to identify, at a certain distance from each other, a loading area for the material to be melted and an area for discharging the melted material.

In basin furnaces, the material is heated by means of combustion heating means mounted directly in the melting chamber, above the bath to be melted.

Currently, in most applications, the basin furnaces are fed with the material to be melted into powder. In particular, the cold material is gradually thrown away in small quantities above the bath where it floats until it melts.

In other embodiments, on the other hand, the use of previously pressed material can be envisaged to form briquettes or crushed stone. The latter are also normally fed in correspondence with a lateral zone of the oven.

In most of the known applications it is then envisaged to use the combustion fumes to preheat the combustion air.

At the patent level, some construction solutions have also been proposed that provide for the preheating of the material as well (see for example US 2597585, US 2057393, US 4877449, US 3944713, US 5057140, EP 547576, US 4940478, US 2009084140, US 4797092, DE 4007115, US 4323384, JP 4310523, JP 60221327, DE 4039608 and DE 4000358). However, these solutions have not found widespread industrial use.

However, the known technology has many drawbacks.

A first drawback is the fact that the productivity of known basin kilns, which is measured as the ratio between the production capacity of the kiln (weight / time) and the extension in plan of the kiln itself, is very poor, and this is due to several reasons.

A further disadvantage of the known furnaces consists in the fact that in them it is very difficult to suitably degas the melt bath. Degassing, in fact, requires that the molten material move as much as possible so as to facilitate the ascent of the air bubbles, especially the smallest ones, while in known basin furnaces the melting bath is practically stationary. It should also be noted that in some applications such as the production of rock wool, in the basin furnaces the combustion must take place in the absence of air, with the consequence that the fumes contain residues of unburned fuel. Consequently, on the one hand there is a decrease in the efficiency of the plant, on the other the production of pollutants.

Currently, then, in order to try to increase the efficiency of the furnace, it is preferred to build basin furnaces of large dimensions, with much higher productivity than those of the downstream plants that use the molten material (for example for the creation of bottles). Consequently, many downstream systems arranged in parallel are combined with each basin furnace. This solution, while allowing to increase the efficiency of the furnace as such, however, has the drawback of requiring long transfer paths of the molten material up to the individual downstream plants, with a consequent high consumption of fuel to compensate for heat losses. along these paths.

In this context, the technical task underlying the present invention is to provide a basin furnace for melting material which remedies the aforementioned drawbacks.

In particular, the technical task of the present invention is to provide a basin furnace for melting material which guarantees a higher productivity with the same basin surface.

Moreover, it is also a technical task of the present invention to provide a basin furnace for melting material which, at least in some embodiments, allows to improve the degassing of the melted material. It is also a technical task of the present invention to provide a basin furnace for melting material which, even in the case of small dimensions, has an efficiency comparable to that of known large-sized basin furnaces.

Regardless of this, it is the technical task of the present invention to provide a basin furnace for melting material that allows the thermal energy produced by combustion to be exploited in the best possible way.

The technical task and the aims indicated are substantially achieved by a basin furnace for melting material in accordance with what is described in the appended claims and / or in the following description.

Further characteristics and advantages of the present invention will become more evident from the detailed description of some preferred, but not exclusive, embodiments of a basin furnace for melting material illustrated in the accompanying drawings, in which:

Figure 1 shows a three-quarter schematic isometric view of a first embodiment of a basin melting furnace according to the present invention;

Figure 2 shows the oven of Figure 1 partially sectioned to highlight the internal structure;

figure 3 shows the oven of figure 1 in front view;

Figure 4 shows the oven of Figure 1 in a side view;

figure 5 shows the oven of figure 4 sectioned along the line V-V; - figure 6 shows the oven of figure 5 with schematically highlighted the material to be melted inside it and the paths of the combustion fumes; - figure 7 shows the oven of figure 3 sectioned along the line VII-VII; - figure 8 shows the oven of figure 7 with schematically highlighted the material to be melted inside it and the paths of the combustion fumes and combustion air;

Figure 9 shows a schematic axonometric view of a second embodiment of a basin melting furnace made in accordance with the present invention;

- figure 10 shows the oven of figure 9 longitudinally sectioned and with some parts removed to better highlight others;

Figure 11 shows a side view of the oven of Figure 10 with schematically illustrated the material inside; And

- figure 12 shows the oven of figure 9 sectioned along the line XII-XII of figure 11.

With reference to the aforementioned figures, the reference number 1 globally indicates a melting furnace made according to the present invention.

In particular, figures 1 to 8 show an oven 1 of small dimensions which can be advantageously used for example in combination with plants for the production of glass fiber, mineral or fried fibers, while figures 9 to 12 show a larger oven 1 generally usable in combination with glass production plants.

It should also be noted that the illustrated furnaces are furnaces intended for melting fed material in the form of briquettes or crushed stone. Nevertheless, many of their parts and characteristics can be indifferently foreseen also in furnaces intended for the melting of powdered material.

As can be seen in the accompanying figures, three main parts can be identified in the kilns represented: a lower part 2 in which the actual melting takes place, an upper part 3 for storing the material 4 to be melted, and an intermediate part 5 which, as better explained below, it allows a correct distribution of the combustion fumes for their use in the preheating phase. For reasons of clarity, the three parts will now be described in succession in this order. The present invention, in fact, relates independently to each of these three parts. This means that the innovative aspects developed by the present invention with reference to each of the three parts of the oven 1 can find application regardless of the presence or absence of the other two parts as well as their specific structure.

The lower part 2 of the furnace 1 first of all defines inside itself a first chamber 6 in which the melting bath 7 is created and into which the material 4 to be melted is gradually introduced. The first chamber 6 is then associated with combustion heating means, normally consisting of one or more burners 8. More in detail, the first chamber 6 is delimited by a lower containment basin 9 intended in use to house the bathroom 7 of molten material and an upper vault 10 mounted above the basin 9. In consideration of the temperatures involved, both the basin 9 and the vault 10 are advantageously made of refractory material 4. The containment basin 9, then, generally comprises a bottom 11 and a perimeter wall 12. It also identifies a loading area 13 for the material to be melted and a discharge area 14 for the melted material. The loading area 13 and the unloading area 14 are advantageously arranged spaced apart from each other, in particular preferably at opposite ends of the basin 9. As far as the unloading area 14 is concerned, it can be made in any known way. in the bottom 11 (figure 8) and in the perimeter wall 12 of the basin 9 (figure 11).

It should be noted that, for the sake of simplicity, the accompanying figures 1 to 8 show a small oven 1 equipped with a single burner 8, while in figures 9 to 12, a larger oven 1 equipped with eight burners 8 ( of which only the corresponding mounting seat 15 is visible in the perimeter wall 12). Nevertheless, the present invention can find advantageous application in ovens of any size equipped with any number of burners 8 or other combustion heating means.

In general, then, the combustion heating means are advantageously associated with means for delivering fuel and combustion air of which, in the embodiments illustrated, only some parts of a system 16 for transporting combustion air are shown, in as for the rest they are of a known type.

The first chamber 6 also has associated means for feeding the material 4 which are structured in such a way as to feed the material 4 inside the basin 9 in correspondence with the loading area 13.

The first characterizing aspect of the present invention, with reference to the lower part 2 of the kiln 1, is the fact that the means for feeding the material 4 (whether in powder or in briquettes or crushed stone or in another form), comprise at least two sections inlet 17 for the material 4 itself, each of which advantageously comprises one or more inlet mouths 18 for material 4 (in the preferred embodiment defined by the upper vault 10). The feeding means also comprise at least one containment body 19 for the material 4 to be melted coupled to each inlet section 17 (the containment body 19 can in any case be one only for all the inlet sections 17 or more than one) to feed them with the material 4 to be melted. It should also be noted that in the embodiment of figures 1-8 each inlet section 17 comprises two inlet openings 18 defined by the vault 10, while in that of figures 9-12 it comprises four.

The inlet sections 17 are mutually spaced from each other and are placed at a height such as to be substantially above the basin 9, meaning at least above the maximum height that can be reached in the basin 9 from the melting bath 7 7 In particular, the inlet openings 18 can be obtained both in the upper vault 10 (as in the embodiments illustrated) and in the perimeter wall 12 of the basin 9 in correspondence with two substantially opposite side sections 20 thereof.

Advantageously, in fact, the two inlet sections 17 are arranged in correspondence with two substantially opposite side sections 20 of the perimeter wall 12 of the basin 9, so that during operation each inlet section 17 is able to create a stack 21 of material 4 in the basin 9, which is opposite to that created by the other inlet section 17. In particular, the two stacks 21 must preferably be substantially opposite each other and must delimit each other, in the first chamber 6, at least one free space 22. As illustrated in Figure 6, each stack 21 on one side is substantially leaning against the relative lateral portion 20 of the containment wall, on the other it presents, for obvious physical reasons, a slope pattern. In the embodiment illustrated in Figures 1 to 8, then, it can be seen how the containment basin 9 in plan has a T shape with the two arms of the T corresponding to the accumulation areas of the two stacks 21 of material 4. In the in the case of figures 9 to 12, on the other hand, the basin 9 has a rectangular plan. In both cases, however, between the two stacks 21 in the basin 9 there remains a longitudinal section free from accumulations of material 4.

In the preferred embodiment, however, the inlet sections 17 are obtained in correspondence of the vault 10 in such a way that the stacks 21 cover the entire internal height of the first chamber 6. In doing so, in fact, in correspondence with the stacks 21 It is possible to minimize the heat losses directed towards the outside since almost all the heat radiated laterally by the fumes or the flame in the free space 22 is absorbed by the two stacks 21 of material 4 (given the temperatures involved, the € ™ irradiation is the main mode of heat transmission). The second characterizing aspect of the present invention, again with reference to the lower part 2 of the kiln 1, is the fact that the free space 22 that in use remains between the two stacks 21, must be occupied by a heat source capable of heating and advantageously dissolve the material 4 present on the two surfaces facing each other of the two stacks 21. In particular, therefore, according to the embodiments, this free space 22 can constitute a section of a flow path for at least part of the fumes combustion (indicated by the arrows in figures 2, 6, 8, 10 and 12; the number 23 distinguishes some of these arrows) and / or a zone of development of a flame 24 created by the heating means. In particular, in the embodiment illustrated in figures 1 to 8 both these conditions occur, while in that of figures 9 to 12, the heat source consists exclusively of the combustion fumes, as better described below.

In order to obtain this result as regards the fumes, it can be foreseen, for example, that the loading area 13 (in the embodiments illustrated with this definition, meaning the entire section of the containment basin 9 which contains the two stacks 21 and which is between esse) is interposed in whole or in part between the rest of the containment basin 9 and at least one discharge chimney, to the structure of which we will return to later on. In this way, in fact, the part of the combustion fumes directed towards the chimney must pass through the free space 22. In the embodiment of figures 9-12, even the loading area 13 is also interposed between the rest of the basin 9 and two fireplaces.

Alternatively, as illustrated in Figure 7, in order to have a flame 24 in correspondence with the free space 22, the loading area 13, which is laterally delimited by the lateral portions 20 of the perimeter wall 12 of the containment basin 9, can face the front of the the remaining part of the containment basin 9, and closed at the rear by a bottom portion 25 of the perimeter wall 12, which is substantially transverse to the side sections 20. Furthermore, the heating means can comprise at least one burner 8 mounted on the bottom portion 25 and facing the free space 22, to develop the flame 24 in it.

As said, in the embodiment illustrated in Figure 7, the free space 22 acts both as a flame development area 24 and as a flow path for at least part of the combustion fumes; a first chimney 26 is in fact connected to the first chamber 6 through a hole 27 obtained in the upper vault 10 at its point of connection to the bottom portion 25 of the perimeter wall 12. Also in the other embodiment illustrated, a first chimney 26 is connected to the first chamber 6 in correspondence with the upper vault 10, this time 10 however by means of a plurality of holes 27 distributed longitudinally. In this second embodiment, however, the free space 22 is also connected at the rear to a second chimney 28.

Although in the preferred embodiment the two opposite stacks 21 are arranged one in front of the other and substantially parallel, in other embodiments they can also be arranged opposite each other and not parallel so as to converge towards each other (for example so to form, seen from above, an open or closed V at the vertex). Or the presence of a third inlet section 17 may be provided, arranged transversely to the first two (for example in correspondence with the bottom portion 25 of the perimeter wall 12, which, in that case, will preferably be without a burner 8) in such a way as to create a third stack 21 that joins the other two (in this way, seen from above, the three stacks 21 are arranged in a C-shape around the free space 22).

However, further arrangement variants are possible.

In the simpler embodiments of the present invention, then, as regards the lower part 2 of the oven 1, the bottom 11 of the basin 9 can all develop on a single level.

In the preferred embodiment, however, it is advantageously provided that in correspondence with the loading area 13, the bottom 11 of the containment basin 9 has a raised area 29 with respect to the rest of the bottom 11 itself, so that the stacks 21 of material 4 are immersed in a bath 7 of reduced or almost zero level. Even more advantageously, in fact, the raised area 29 is placed at a higher altitude than the maximum level that, during operation, the bathroom 7 can take inside the remaining part of the containment basin 9 (figure 8 and 12). In this way, in fact, the stacks 21 of material 4 are outside the bath 7 and, as far as the molten material is concerned, they are affected exclusively by that which gradually melts. Consequently, on the one hand the entire surface of the stacks 21 facing the free space 22 is subject to direct heating by the flame 24 and / or the fumes, on the other hand there is no risk that the bath 7 of fusion 7 can cause erosion of the slopes nor, consequently, that any solid blocks can be dragged into the bath 7 itself.

Depending on the requirements, then, the raised area 29 of the bottom 11 can be horizontal or slightly inclined in order to facilitate the flow of the molten material towards the lower part of the bottom 11.

As can be seen in figures 8 or 12, a separation step 30 can be provided between the raised area 29 and the rest of the bottom 11. In other embodiments, however, the passage from the raised area 29 to the rest of the bottom 11 can also take place by means of a gradual level variation or with several steps. Advantageously, however, the presence of a moving path between the melting zone of the material 4 and the actual melting bath 7 can have beneficial degassing effects of the melted material.

In the preferred embodiment of the lower part 2 of the furnace 1, finally, in correspondence with each lateral portion 20 of the perimeter wall 12, at least one thrust element (two in the accompanying figures 1 to 8) can be provided which can be activated to move the material 4 placed in the relative stack 21 and thus facilitate the entry of new material 4 from the relative inlet section 17. Each thrust element is advantageously constituted by a linear actuator 31 whose head 32 is movable between a position in which it is ̈ coplanar with the surface of the lateral sections 20 of the perimeter wall 12, and a position in which it protrudes from it inside the first chamber 6. Moving now to the upper part 3 of the oven 1, it should first of all be remembered that the relative innovative aspects can be application regardless of the structure of the lower part 2 and of the intermediate part 5. In particular, although in the illustrated embodiments the upper part re 3 is associated with a lower part 2 made in such a way as to create at least two stacks 21 of material 4, in accordance with the more general embodiment of the present invention, the structure of the upper part 3 of the kiln 1 can find advantageous application also in the in the case of ovens with a single inlet section 17 (and a consequent single stack 21 of material 4) as well as in ovens in which the material 4 is inserted inside the first chamber 6 in other ways.

As regards the upper part 3 of the furnace 1, in fact, the present invention first of all envisages the presence of means for recovering at least part of the fumes produced by combustion in order to preheat both the material 4 to be melted and the combustion air. These recovery means comprise at least one aspirator 33 associated at least with the first chimney 26 which, as mentioned, is in turn 10 in fluid communication with the first chamber 6.

More in detail, in accordance with the present invention as regards the upper part 3 of the furnace 1, the containment body 19 comprises an external containment structure 34 and at least a first air-to-air heat exchanger 35 at least partially inserted in the Inside of the external containment structure 34 according to the methods better explained below.

The first heat exchanger 35 is made in such a way as to define a first flow path for a first fluid and at least a second flow path for a second fluid, such as to be in a heat exchange relationship. The first flow path forms part of the first chimney 26 while the second path forms part of the plant 16 for transporting the combustion air to the combustion heating means.

In the illustrated embodiment, the first exchanger 35 comprises an internal containment structure 36 which identifies a compartment 37 which defines the first flow path, inside which a plurality of ducts 38 are mounted which define the second flow path. More in detail, the internal containment structure 36 comprises a first front vertical wall 39 and a first rear vertical wall 40 through which said ducts 38 are sealed, and two first shaped side walls 41 which have a lower vertical section and a upper section inclined towards the other wall. The internal containment structure 36, on the other hand, is open at the bottom and at the top in such a way as to constitute respectively a lower end 42 and an upper end 43 of the first sliding path. The lower end 42 is in fluid communication with the first chamber 6 and has a significantly higher through section than the upper end 43.

Advantageously, then, the various ducts 38 are mutually connected in series and / or in parallel and are arranged transversely with respect to the first sliding path (horizontal in the accompanying figures). In the preferred embodiment, in particular, the ducts 38 are divided into two groups, an upper group 44 and a lower group 45. All the ducts 38 of each group are connected in parallel, while in the ducts 38 of the two groups they are run in the direction opposite to.

For this purpose, between the first vertical front wall 39 and the external containment structure 34 there is an inversion chamber 46 in which all the ducts 38 converge to allow the air coming out of the upper group 44 to enter the lower group 45, while between the first rear vertical wall 40 and the external containment structure 34 there is an inlet chamber 47 in communication with the ducts 38 of the upper group 44 and an outlet chamber 48, separated from the inlet chamber 47, in which the ducts 38 of the lower group 45 flow into the inlet chamber 47 an inlet sleeve 49 fed in use with cold combustion air is then connected, while an outlet sleeve 50 is connected directly to the outlet chamber 48 (as in figure 7) or indirectly (as in figure 11) to the combustion heating means. In this way, the cold air that flows through the ducts 38 of the upper group 44 is heated by colder fumes that have already transferred part of their heat to the ducts 38 of the lower group 45 inside which the partially heated air flows. . The first exchanger 35 illustrated is therefore a substantially counter-current exchanger.

In accordance with the present invention, then, between the external containment structure 34 and the first exchanger 35 a second chamber 51 is identified which is in communication with the inlet section 17 and is intended to constitute a warehouse to accommodate the 4 material to be cast. Again in accordance with the present invention, the second chamber 51 at least partially surrounds the first heat exchanger 35 in order to recover any thermal dispersions thereof. Furthermore, the second chamber 51 is also part of the first flue 26 for the fumes, being in fluid communication both with the aspirator 33 and with the first chamber 6.

In the illustrated embodiment, in particular, the second chamber 51 surrounds the first exchanger 35 above and on two opposite sides, while the other two sides of the first exchanger 35 are substantially defined by the same external containment structure 34 (as already seen in relation to the inlet chamber 47, to the outlet chamber 48 and to the inversion chamber 46). Furthermore, both the first exchanger 35 and the external containment structure 34 are coupled below to the first chamber 6. More in detail, the external containment structure 34 in turn 10 comprises a second front vertical wall 52 and a second rear vertical wall 53. (which also delimit towards the outside also the inlet chamber 47, the outlet chamber 48 and the inversion chamber 46), and two convex side walls 54 which converge towards an upper opening 55 for inlet material 4. Depending on the requirements the upper opening 55 can always be open, can be closed with suitable mobile means (preferably sealed so as to avoid accidental entry into the second chamber 51 of cold air) or equipped with means for dosing the material 4 to be melted.

Returning to the first exchanger 35, in the preferred embodiment, the first flow path is advantageously in fluid communication on one side with the first chamber 6, on the other with the second chamber 51. The upper end 43, in fact , advantageously opens in the upper part of the second chamber 51; to prevent the material 4 from entering the first exchanger 35, moreover, the upper end 43 is protected by a first flange 56, with an inverted V section, mounted in the first chamber 6. In this way the aspirator 33 , which is in fluid communication with the second chamber 51, can suck the fumes from the first chamber 6 either by making them pass in series the first heat exchanger 35 and the second chamber 51, or by making them pass through the second chamber 51 only. that is, two parallel ways of evacuation of the fumes inside the first chimney 26. In other embodiments, however, the upper end 43 of the first exchanger 35 can also be connected to the aspirator 33 not through the second room 51.

More in detail, to put the second chamber 51 in communication with the aspirator 33, the first chimney 26 has one or more outlets 57, 61 from the second chamber 51. In the case in which the upper opening 55 of the second chamber 51 is always open and therefore allows easy entry of cold external air, it is then advisable that each outlet 57 is arranged at a distance from the upper opening 55 such that, with the second chamber 51 full of material 4, the pressure drops are lower along a path which, through the material 4 and / or the first exchanger 35, joins the outlet 57 to the first chamber 6 with respect to a path that joins the same outlet 57 to the Top opening 55. In this way, in fact, following the action of the aspirator 33, at least the hot fumes are drawn in, not cold air. To maintain this effect over time, it is also advisable that during operation the material level 4 inside the second chamber 51 is always kept above a pre-established minimum level (it is therefore preferable to keep the level almost stable with limited topping up almost continuously). In the illustrated embodiments this is achieved by applying a material loading hopper 58 to the central part of the upper opening 55 and making sure to always maintain a certain level of material 4 inside the hopper. In this way, in fact, it is possible to maintain constant over time the pressure drops determined by the path that goes from the lateral portions 59 of the upper opening 55 to the outlets 57, 61. In the preferred embodiments, then, all the outlets outlets 57, 61 are defined by a second shaped flange 60 fixed to the inside of the external containment structure 34 and extending downwards to prevent, accidentally, material 4 from entering them.

As can be seen in figures 6 to 12, then, one or more first outlet openings 57 are advantageously provided, intended at least mainly for the suction of fumes that have only passed through the second chamber 51, and one or more second outlet openings 61 intended at least mainly to the suction of the fumes that have passed through the first exchanger 35 and the second chamber 51 in series. This result is obtained by positioning the second outlet openings 61 at a greater distance from the inlet section 17 (higher in the units figures) with respect to the first outlets 57.

In the illustrated embodiment in which the oven 1 has two inlet sections 17, two first outlet openings 57 and two second outlet openings 61 substantially specular are provided. However, their number may vary depending on the application. Outside the external containment structure 34, the first outlets 57 and the second outlets 61 on each side can flow into a single suction chamber. Advantageously, moreover, all the outlets 57, 61 are connected to a single aspirator 33 (Figure 5). Eventually, therefore, the aspirator 33 can be connected to only one of the two aspiration chambers.

In order to ensure that the fumes can have constant access to the inside of the second chamber 51, further passages can be advantageously provided, in addition to the inlet sections 17, which put the first chamber 6 and the second chamber 51 in fluid communication. operation, in fact, the inlet section 17 can be completely or partially obstructed by the material 4 which is melting. In the preferred embodiment, these passages are obtained by means of distribution means of the fumes which are such as to divide the fumes themselves between the second chamber 51 and the first flow path of the first heat exchanger 35. The structure of these preferred distribution means however, it will be better described in relation to the intermediate part 5 of the oven 1 object of the present invention.

In the embodiment illustrated then, where the feeding means have at least two material inlet sections 17 4 placed on two distinct sides of the lower end 42 of the first sliding path of the first exchanger 35, two branches can be identified in the second chamber 51 62 lower parts separated from each other which extend downwards starting from an upper connecting portion 63, which the upper opening 55 faces. These branches 62 are arranged on two opposite sides of the first heat exchanger 35 and they are each in communication with one of the inlet sections 17 to feed it with the material 4 to be melted.

In the embodiment of figures 9-12, as regards the part of the oven 1 intended for preheating, it is finally provided that the oven 1 also comprises at least a second chimney 28 for the evacuation of a different part of the fumes (figure 11 ). Furthermore, it is envisaged that the furnace 1 also comprises at least a second heat exchanger 64 of a known type (for example a coaxial coaxial exchanger as in the accompanying figures, or a regenerative refractory exchanger) mounted along the second chimney 28 to further heat the Combustion air leaving the second path of the first exchanger 35. As can be seen, in fact, the air leaving the outlet sleeve 50 of the first exchanger 35 is sent to the second exchanger 64; in turn 10, although this is not shown, the air leaving the second exchanger 64 is sent to the combustion heating means of the furnace 1.

The embodiments described up to now in detail in relation to the upper part 3 of the furnace 1 are embodiments intended mainly for furnaces in which the material 4 is fed in the form of briquettes or crushed stone; in that case, in fact, the fumes can pass through the material 4 without the need for particular precautions.

In its most general embodiment, however, the present invention, as regards the upper part 3 of the oven 1, must be understood as applicable also in the case of material 4 in powder form. In that case, in fact, the passage of the fumes through the second chamber 51 can be obtained with other methods, for example by means of a plurality of pipes passing through the second chamber 51 or other similar solutions. Finally, moving on to the intermediate part 5 of the oven 1, it should first of all be emphasized that also in this case the relative innovative aspects can be applied independently of the structure of the lower part 2 and of the upper part 3, as well as that its presence is neither indispensable nor for the lower part 2 nor for the upper part 3 described above. In particular, although in the embodiments illustrated the intermediate part 5 is associated with a lower part 2 made in such a way as to create at least two stacks 21 of material 4, and with an upper part 3 which provides for the parallel preheating of the material 4 and of the € ™ combustion air, in its most general embodiment, the structure of the intermediate part 5 of the furnace 1 in accordance with the present invention, can also find advantageous application in the case of furnaces with a single inlet section 17 (and a consequent single stack 21 of material 4), or in ovens in which the material 4 is inserted inside the first chamber 6 in other ways, as well as in ovens in which only the preheating of the material 4 is foreseen, not necessarily that of the air .

As regards the intermediate part 5 of the oven 1, in fact, in accordance with the present invention, it is mainly intended to allow the insertion of the fumes inside the material 4 stored for preheating it, where the material 4 is under form of briquettes or crushed stone or have a sufficiently high particle size for the purpose.

In general, therefore, with reference to the intermediate part 5 of the furnace 1, the present invention can find application in any type of basin furnace 1 in which a part of the fumes is passed through the material 4 contained in a warehouse (such as for example the second chamber 51 in the illustrated embodiment) which at least partially constitutes part of the first flue 26 for evacuation of the fumes.

In accordance with the present invention it is in fact provided that the oven 1 comprises at least one air distributor 65 directly associated with the inlet section 17 and interposed between the first chamber 6 and the store to put them in fluid communication by means of a distinct passage with respect to the inlet section 17 of the material 4. In this way, in fact, the distributor 65 allows the combustion fumes to pass from the first chamber 6 to the warehouse without the need for them to pass through the inlet section 17, thus avoiding possible problems of obstruction due to the melting of the material 4 at the inlet section 17 itself. It should be noted that, in relation to the intermediate part 5 of the furnace 1, with the definition inlet section 17 we mean any passage through which the material 4 can enter the first chamber 6, not necessarily an inlet section 17 of the type described above. with reference to the lower part 2 of the furnace 1. In the preferred embodiment, in particular, the distributor 65 comprises at least one tubular structure 66 which internally defines a first material sliding channel 67 coupled below the inlet section 17. Advantageously the tubular structure 66 has the shape of a hopper. At least one channel extends through the tubular structure 66 itself from the outside to the first channel 67; since the outside of the tubular structure 66 is in fluid communication with the first chamber 6, this channeling allows to receive part of the fumes from the first chamber 6 and to introduce it into the first channel 67.

In the illustrated embodiment, the channeling comprises first of all at least a second channel 68 obtained through the tubular structure 66 and which extends from the outside up to the first channel 67. As can be seen in Figure 6, this second channel 68 can be constituted by a recess obtained in the lower edge of the tubular structure 66 and coupled to the upper vault 10 which identifies the inlet section 17.

A groove 69 obtained in the tubular structure 66 in correspondence with the first channel 67 is then connected to the second channel 68. The groove 69 extends at least partially around the first channel 67 itself, advantageously completely as in the illustrated embodiments. According to the embodiments, the warehouse can be constituted both by an additional element placed above the tubular structure 66, such as the containment body 19 and the relative second chamber 51 described above, and by the tubular structure 66 itself (and in particular by its part above the groove 69 corresponding to which the fumes for preheating are introduced).

In preferred embodiments, the distributor 65 comprises a plurality of tubular structures 66 arranged side by side for each inlet section 17 (advantageously one for each inlet 18). With the same overall section of the first channels 67, in fact, by increasing the number of tubular structures 66 it is possible to reduce the length of the grooves 69 and thus make the distribution of the fumes around and inside each first channel 67 more uniform.

In the case of the embodiment illustrated, then, in which the oven 1 comprises several distinct inlet sections 17, the distributor 65 is directly coupled to each of them.

If the furnace 1 also comprises a first heat exchanger 35 for preheating the combustion air, the distributor 65 advantageously also comprises a third chamber 70 for distributing the fumes in fluid communication on one side with the first chamber 6 and from the € ™ other both with the warehouse and with the first heat exchanger 35.

In the preferred embodiment, in particular, the third chamber 70 has a longitudinal direction of development (perpendicular to the sheet in figures 6 and 12); in turn 10, the inlet sections 17 and the relative tubular structures 66 are arranged symmetrically with respect to a vertical plane passing through this longitudinal direction of development (Figure 9).

Advantageously, then, given that in some applications in melting furnaces the heating means are normally fed with a mixture characterized by a certain scarcity of combustion air (fat flame 24) in order to increase the length of the flame 24 and to prolong the combustion time, and since, consequently, the fumes leaving the first chamber 6 in a first phase are still at the combustion temperature and contain residues of unburned fuel, in the preferred embodiment the air distributor 65 comprises moreover at least a fourth chamber 71 for completing the combustion in correspondence with which means for injecting further combustion air (not shown) can be mounted. In this way, in fact, on the one hand the unburnt materials can be eliminated by reducing the presence of pollutants in the fumes, on the other hand the combustion heat can be exploited for preheating.

In the embodiment illustrated in the accompanying figures, the fourth chamber 71 is located substantially centrally to the distributor 65, while the third chamber 70 surrounds it above and laterally with respect to the longitudinal direction of development. Advantageously, moreover, only the fourth chamber 71 is in direct fluid communication with the first chamber 6, while the third chamber 70 is in fluid communication with the first chamber 6 only through the fourth chamber 71. In turn 10 each channeling is in fluid communication with the first chamber 6 through the third and fourth chambers 71.

Finally, it should be noted that the intermediate part 5 of the oven is similar in both embodiments illustrated with the only difference that in the case of the second embodiment it has a longitudinally doubled structure (in fact it has four tubular structures 66 on each side instead of two as in the case of the first embodiment). In order to avoid the entry of cold external air into the tubular structures 66, each of them is then equipped with a closing lid 72 (for inspections and maintenance interventions) in correspondence with the upper part not aligned with the containment body, as illustrated in figure 9. Said cover 72 has instead been removed in figure 1 in order to make the internal structure of the tubular structures 66 better visible.

The operation of the oven 1 derives from the structural description given above.

In particular, as regards the preheating of the material 4, in the illustrated embodiment it begins in the upper part 3 of the second chamber 51 where the relatively cold fumes are introduced (with temperatures that can be of the order of 250-300 ° C) in exit from the first exchanger 35. As the material 4 descends it is instead hit by the fumes introduced directly into the second chamber 51 through the distributor 65, fumes which have much higher temperatures (of the order of 600 ° C). Furthermore, at least in the section between the groove 69 and the first outlets 57 the fumes and material 4 move in countercurrent with the temperature of the fumes which decreases towards the first outlets 57 and that of the material 4 which increases towards the outlet section. entrance 17.

Advantageously, the residence time of the material 4 in the second chamber 51 can be of the order of a few hours so that the preheating takes place in the best way with the material 4 entering the first chamber 6 with a temperature very close to the melting point. Its preheating is then completed in the laying time in the stacks 21.

In general, in fact, the temperature of the material 4 can reach 400-500 ° C inside the second chamber 51, 800-900 ° C inside the tubular structures 66 and finally 1200-1300 ° C in stacks 21.

As regards the preheating of the air, by means of the first exchanger 35 the temperature can be brought to approximately 400-500 ° C. If the second exchanger 64 is present, in the usual way, it can then also be brought up to 700-750 ° C with a second steel exchanger 64 (such as the one shown in the accompanying figures) or even up to 1200-1300 ° C with a regenerator as a second exchanger.

The context of the present invention also includes a method for melting solid material 4 in basin 9 melting furnaces, as well as a method for managing a basin 9 melting furnace 1.

As regards the first method, it is intended to be implemented in basin furnaces 9 in which heat is generated by combustion, and first of all provides for inserting the material 4 into a first melting chamber 6 of the furnace 1, in correspondence with a loading area 13 forming two opposing stacks 21 which delimit a free space 22 between them and which emerge upwards with respect to a melting bath 7 7 of the furnace 1. Once this is done, the method provides for at least part of the fumes to flow combustion and / or to cause a flame 24 to develop in correspondence with the free space 22, so as to gradually melt the material 4 which is on the surface of each stack 21 that faces the free space 22. Preferably, then, the material 4 is inserted into the kiln 1 in such a way that the stacks 21 cover, in height, the entire internal height of the first chamber 6, so as to minimize heat losses towards the outside.

Advantageously, in the preferred embodiment, it is provided that the stacks 21 are formed in a raised position with respect to the main melting bath 7 of the furnace 1, and that the material 4 which gradually melts from the stacks 21 is made to pour from the ™ high in main melt bath 7. In this way, in fact, the freshly melted material 4 forms a thin layer which moves relatively quickly, a factor which facilitates its degassing, especially with reference to the inclusions of small air bubbles.

In the preferred embodiment, then, this melting method is carried out using material 4 in briquettes or crushed stone, preheated or not.

As regards the management method of a basin 9 melting furnace 1, it finds advantageous application with furnaces which are equipped with an upper part 3 similar to that described above with reference to the present invention.

In fact, this method provides for inserting the material 4 to be melted, in the form of briquettes or crushed stone, into a first chamber 6 of the furnace 1, generating heat in the first chamber 6 by means of a combustion of a mixture of combustive air and fuel, and of preheat the material 4, before inserting it into the oven 1, and the combustion air before their combustion.

In accordance with the present invention, then, as regards the combustion air preheating phase, the method object of the present invention provides for implementing it using a first part of the combustion fumes leaving the first chamber 6 (in the preferred embodiment this is obtained by making the first part of the fumes pass along a first path of a first heat exchanger 35 and the air along a second path of the first heat exchanger 35 in a heat exchange relationship with the first path).

As regards the preheating phase of the material 4, on the other hand, it is first stored in a heap in which a first portion closer to the first chamber 6 and a second portion further away can be identified. At that point, when the material 4 is in correspondence with the second portion of the heap, the preheating method provides for heating it by making it pass through the first part of the fumes already used to heat the air. Subsequently, when the material 4 has reached the first portion, the method instead provides for heating it by making it pass through a second part of the combustion fumes arriving from the first chamber 6 without having previously been used for any preheating.

Advantageously, then, in the case of use of a first exchanger 35, the method envisages at least partially surrounding the first heat exchanger 35 with the heap of briquettes or crushed stone waiting to enter the furnace 1 to heat them also with any thermal dispersions coming from the first exchanger 35 itself.

The present invention achieves important advantages, with reference to each of the three main parts into which the oven can be divided.

As regards the lower part, the fact that the material is introduced into the melting chamber by means of two stacks, first of all considerably improves the productivity of the kiln with the same overall dimensions in plan, as each stack has a heat exchange surface at vertical development. Secondly, given that each stack substantially covers a part of the perimeter wall of the basin, it determines a lower thermal dispersion towards the outside. Using the free space between the stacks for the flame or for the flow of fumes, it is possible to maximize the combustion efficiency.

Consequently, the efficiency of the oven is also improved.

The fact of using the material in briquettes or crushed stone in stacks also allows to avoid that, accidentally, the still solid material can be transported too quickly towards the unloading area.

This effect is obtained even better in the embodiment in which the stacks are created on a raised portion of the bottom of the basin. Furthermore, in this case, as mentioned, a high degassing effect is also obtained.

As regards the upper part of the furnace, the main advantage obtained is that of having a high recovery of the heat of the fumes, such that both the material and the air are introduced into the melting chamber at a very close temperature. respectively to that of fusion and to that of combustion.

Consequently, the introduction of new material does not involve, as in known ovens, significant variations of the entire temperature inside the oven. The introduction into the furnace of material already at a high temperature, instead of at room temperature as in known furnaces, allows the internal temperature of the entire chamber to be kept substantially unchanged. The upper part of the oven therefore also cooperates in improving efficiency.

Finally, as regards the intermediate part, the mere fact of having conceived it allows to guarantee a better preheating of the material. In the most complete embodiments, then, it allows to eliminate the presence of unburnt materials in the fumes.

In general, thanks to the present invention, it is possible on the one hand to produce large-sized furnaces with better efficiency, and on the other hand to produce small-sized furnaces with efficiencies comparable to those of known large-sized furnaces. And this can also be achieved without the use of regenerators as in known types of plants.

In this second case, therefore, it is possible to create industrial plants in which each furnace is combined with a single downstream plant, with the advantageous consequence that, when a downstream plant must not be used, it is possible to avoid using the relative oven.

Finally, it should be noted that the present invention is relatively easy to produce and that also the cost connected with its implementation is not very high.

The invention thus conceived is susceptible of numerous modifications and variations, all falling within the scope of the inventive concept that characterizes it.

All the details can be replaced by other technically equivalent ones and the materials used, as well as the shapes and dimensions of the various components, may be any according to requirements.

Claims (12)

CLAIMS 1. Basin furnace for melting material (4), comprising: a containment basin (9) for a bath (7) of molten material, having a bottom (11) and a perimeter wall (12), in said basin (9) a loading area (13) for the material to be melted is also identified and a discharge zone (14) for molten material arranged spaced apart from each other; an upper vault (10) mounted above the containment basin (9) to create with it a first chamber (6); material feeding means (4) inside the basin (9) in correspondence with the loading area (13); And combustion heating means associated with the first chamber (6); characterized by the fact that the feeding means comprise at least two inlet sections (17) for the material (4) to be melted, mutually spaced and placed above the basin (9) in correspondence with two substantially opposite side sections (20) of the perimeter wall (12 ) of said basin (9), so that each inlet section (17) creates a stack (21) of material (4) in said basin (9) opposite to that created by the other inlet section (17) ; the inlet sections (17) being arranged in such a way that, during operation, the relative stacks (21) delimit one another in said first chamber (6) at least one free space (22); and by the fact that the free space (22) constitutes a portion of a flow path for at least part of the combustion fumes and / or a zone of development of a flame (24) created by the heating means. 2. Basin furnace according to claim 1 characterized in that the bottom (11) of the containment basin (9) has a raised area (29) with respect to the rest in correspondence with the loading area (13). 3. Basin oven according to claim 2 characterized by the fact that the raised area (29) is placed at a higher altitude than the maximum level that the bathroom (7) can assume, during operation, inside of the remaining part of the containment basin (9). 4. Basin furnace according to any one of the preceding claims, characterized in that the loading area (13) is interposed between the rest of the containment basin (9) and at least a first exhaust flue (26) for said part of the fumes combustion. 5. Basin furnace according to any one of the preceding claims, characterized in that the loading area (13) faces the rest of the containment basin (9) frontally, and is laterally delimited by said side sections (20) of the wall perimeter (12) of the containment basin (9) and at the rear it is delimited by a bottom portion (25) of the perimeter wall (12), substantially transversal to said lateral sections (20), and by the fact that the heating means comprise at least one burner (8) mounted on the bottom portion (25) to develop a flame (24) in the free space (22). 6. Basin furnace according to any one of the preceding claims, characterized in that it further comprises, on each lateral portion (20), at least one thrust element which can be activated to move the material (4) placed in the relative stack (21). 7. Basin furnace according to any one of the preceding claims, characterized by the fact that each inlet section (17) comprises one or more inlet openings (18) for material (4) obtained in the upper vault (10) or in the relative lateral section (20 ) of the perimeter wall (12), and in that the feeding means comprise at least one body (19) for containing the material (4) mounted above said mouths so as to feed them with the material (4). Basin furnace according to any one of the preceding claims, characterized in that it is a furnace (1) for melting material (4) into briquettes or crushed stone. 9. Method for melting solid material in basin melting furnaces, in which heat is generated by combustion, characterized in that it comprises the operational steps of: insert the material (4) into a first melting chamber (6) in correspondence with a loading area (13) of the basin furnace (1) forming two opposing stacks (21) which delimit a free space between them (22) and which emerge upwards with respect to a melting bath (7) (7) of the furnace (1); in said free space (22) to let at least part of the combustion fumes flow and / or to develop a flame (24), in such a way as to gradually melt the material (4) which is on a surface of the stacks (21) facing to said free space (22). 10. Method according to claim 9 characterized in that said stacks (21) are formed in a raised position with respect to a main melting bath (7) of the furnace (1), and in that the material (4) which gradually melts from the piles (21) is made to pour from above into the main bathroom (7). Method according to claim 9 or 10 characterized in that the material (4) is placed in the furnace (1) in briquettes or crushed stone, preheated or not. 12. Method according to claim 9, 10 or 11 characterized by the fact that the material (4) is inserted into the furnace (1) in such a way that the stacks (21) cover, in height, the entire internal height of the first chamber (6).