A MODULAR TUNNEL KILN, AND A METHOD AND EQUIPMENT FOR MOUNTING THETUNNEL KILN

Technical Field

The present invention regards a tunnel kiln for firing ceramic products, typically ceramic tiles, and includes a method and equipment for mounting the tunnel kiln. Background Art As is known, a tunnel kiln for firing ceramic products generally comprises an external support structure, typically constructed with metal materials, which is completely covered internally with cladding in a refractory material, thus defining the long firing tunnel, the internal temperature of which is generated and controlled using multiple burners. The ceramic products are made to advance inside the firing tunnel supported on special transport devices which are designed to resist the high operating temperatures.

Generally the length of a firing tunnel can extend to many dozens of metres, and can vary depending on the specific requirements of the individual kiln. For these reasons tunnel kilns are usually modular and made up from a series of prefabricated assemblable modules, each of which forms a limited section of the firing tunnel.

Each assemblable module generally comprises a single channel-shaped metal support structure which is internally clad with refractory material. The assemblable modules are produced in dedicated production plants and subsequently transported to the installation site where they are arranged in columns and fixed end to end to create a continuous channel of the required length, which is then completed with a roof of refractory material that closes the top of the channel to form the firing tunnel. The transport of the assemblable modules from the production plant to the installation site

requires that the modules are stowed inside suitable containers, such as for example standard transport containers.

Due to their channel shape the assemblable modules occupy a lot of space inside the containers, leaving large empty volumes. For this reason transport typically requires a large number of containers that are only partially filled, resulting in relatively high costs.

The aim of the present invention is to eliminate the inconvenience described above, by providing a modular tunnel kiln that can be transported more efficiently and economically when compared with the prior art. A further aim of the invention is to provide a method and equipment for the assembly of the modular tunnel kiln.

Finally, the invention aims to achieve the above objectives by way of a simple, rational solution at a limited cost.

These aims are achieved by the invention as characterized in the independent claims. The dependent claims define preferred embodiments and characteristics of the invention.

Disclosure of Invention

In general a modular kiln for firing ceramic products is provided in the form of multiple assemblable modules arranged in a column and together forming an external support structure which supports an internal cladding of refractory material that defines a firing tunnel for ceramic products.

In the present invention each individual assemblable module is in turn modular, in the sense that it is realized by the assembly of a set of prefabricated assemblable elements. In particular, the prefabricated elements comprise two distinct lateral flanks, aligned facing each other, between which at least one bottom element is interposed, and fastening means serving to fix the lateral flanks to the bottom element.

This solution makes it possible to manufacture the lateral flanks and the bottom element in special dedicated production sites and more easily, rationally, and economically transported to the installation site as compared with known art, efficiently occupying most of the space available inside

standard transport containers.

After reaching the installation site the lateral flanks can then be assembled with the bottom element in order to form a complete assemblage module, which will in turn be combined with and fixed to other similar assemblage modules to form the tunnel kiln.

Sealing elements are preferably interposed between each lateral flank and the bottom element, acting to form a pneumatic seal and so ensuring that the finished kiln firing tunnel is airtight.

Preferably, the lateral flanks are identical to each other in transversal section and are fixed in a laterally inverted arrangement on opposite sides of the bottom element.

This effectively reduces the number of different prefabricated elements that need to be produced for the realization of the tunnel kiln, significantly reducing production and assembly costs. In a preferred embodiment of the invention both the lateral flanks and bottom element comprise a bearing frame, preferably made of metal materials, to which a wall of refractory material is fixed.

The bearing frame will form part of the external support structure of the tunnel kiln, while the wall of refractory material will form part of the internal cladding delimiting the firing tunnel.

In more detail, the bearing frame of the bottom element is in the form of a flat horizontal base on which a substantially flat layer of refractory material is supported.

The bearing frame of each lateral flank has a substantially L shaped transversal profile, comprising a narrow horizontal base portion on which a substantially vertical wall of refractory material is supported, and a more extended upright portion providing lateral support for the back of the wall of refractory material.

Each lateral flank preferably includes multiple ground support feet which are fixed to the bearing frame base portion below the wall of refractory material.

In a preferred aspect of the invention the fastening means comprise, for each lateral flank, at least one projecting shelf, which is fixed to the bottom

- A -

element and located below the lateral flank.

The distance separating the projecting shelf from the lower edge of the lateral flank makes it possible to effectively compensate errors during the production of the component parts. The fastening means also comprise means for compensating which are interposed between the projecting shelf and the lateral flank, and fastening means serving to retain the means for compensating between the projecting shelf and the lateral flank.

In a first embodiment of the invention, the means for compensating comprise filler elements of various dimensions, for example one or more superimposed metal plates, which are interposed between the projecting shelf and the lateral flank.

In an alternative embodiment, the means for compensating comprise at least one adjustment screw oriented vertically, screwed into a threaded hole in the projecting shelf so as to act upwards from below against the lateral flank.

In this way, by turning the adjustment screw it is possible to create a direct connection between the projecting shelf and the base portion of the lateral flank that compensates the space between the two.

The fastening means preferably include at least one fixing screw oriented vertically, which inserts freely into a hole in the projecting shelf and screws into a threaded hole in the above lateral flank.

In this way the fixing screw acts to vertically compress the projecting shelf and the lateral flank against the means for compensating interposed between them. Alternatively, or in addition to the fixing screw, the invention foresees that the fastening means can comprise one or more welds uniting the projecting shelf to the lateral flank with the means for compensating interposed between them.

In a further preferred embodiment of the invention, completion of the assemblable module is foreseen by directly connecting the tops of the lateral flanks with one or more rigid crossbars, made for example of a metal material, which could also serve as supports for the roofing of the tunnel kiln.

The invention also provides a method for the correct and effective assembly of the lateral flanks and the bottom element, as well as assembly equipment designed to facilitate the implementation of this method. Brief description of the Drawings Further characteristics and advantages of the invention will better emerge from the detailed description made herein, provided by way of no-limiting example, with reference to the accompanying figures of the drawings, in which:

- figure 1 is a front relief view of an assemblable module for the realization of a tunnel kiln according to the invention;

- figure 2 is a front relief view of the lateral flank of the assemblable module of figure 1 ;

- figure 3 is a side relief view of the lateral flank of figure 2;

- figure 4 is a front relief view of a bottom element of the assemblable module of figure 1 ;

- figure 5 is a plan view of the bottom element of figure 4;

- figure 6 is a front relief view of an assembly tool used to assemble the assemblable module of figure 1 ;

- figure 7 is a plan view of the assembly tool of figure 6; - figure 8 is a side relief view of the assembly tool of figure 6;

- figures 9a and 9b are respectively a front relief view and a side relief view of a removable frame of the equipment in figure 6;

- figure 10 is detail A of figure 7 in enlarged scale;

- figure 11 is the cross-section Xl-Xl of figure 10; - figure 12 is detail B of figure 8 in enlarged scale;

- figure 13 is a front relief view of the assembly equipment of figure 6, during the first phase of assembly of the assemblable module of figure 1 ;

- figures 14 and 15 are plan views of figure 13 showing two successive stages of the first phase of assembly; - figure 16 is a side relief view of figure 13 at the end of the first phase of assembly;

- figure 17 is detail C of figure 16 in enlarged scale;

- figures 18 and 19 are front relief views of the assembly equipment of figure 6 during two subsequent stages of a second phase of assembly of the assemblable module of figure 1 ;

- figure 20 is a relief side view of the equipment illustrated in figures 18 and 19 during the second phase of assembly;

- figures 21 and 22 are respectively details E and F of figure 20;

- figure 23 is the cross-section XXIII-XXIII of figure 21 ;

- figure 24 is a partial relief front view of the assembly equipment of figure 6 during a third phase of the assembly procedure of the assemblable module of figure 1 ;

- figure 25 is detail H of figure 24 in enlarged scale;

- figures 26 and 27 are relief side views of figure 24 in two different stages during the third phase of assembly;

- figure 28 is a relief front view of the assembly equipment of figure 6 at the end of the third phase of the assembly procedure of the assemblable module of figure 1 ;

- figure 29 shows figure 28 after a phase of fixing the prefabricated parts that form the assemblable module of figure 1 ;

- figure 30 is detail L of figure 29 in enlarged scale; - figure 31 is an alternative to the solution shown in figure 29. Best Mode for Carrying Out the Invention

The assemblable module 1 of figure 1 is intended for arrangement in a column with other identical assemblable modules 1 , for the realization of a tunnel kiln for firing ceramic products. Overall, the assemblable module 1 comprises an external support structure 10 of a channel shape, preferably in metal material, covered internally with a cladding 11 of refractory material which forms, in combination with the refractory material of other assemblable modules 1 , a firing tunnel through which ceramic products are made to advance inside the kiln. The assemblable module 1 is realized in modular form, that is, it is realized by assembly of a set of prefabricated components, which can be advantageously produced in dedicated production plants and assembled

directly at the installation site.

In particular, the prefabricated components comprising the assemblable module 1 comprise a substantially flat bottom element 2, and two lateral flanks 3, substantially vertical in development. As shown in figure 2, each lateral flank 3 comprises a bearing frame 30, preferably constructed from steel elements, on which a wall 31 of refractory material is fitted.

The bearing frame 30 is intended to form a section of the support structure

10 of the assemblable module 1 , while the wall of refractory material 31 is intended to form a portion of the refractory cladding 11.

In particular, the bearing frame 30 exhibits a substantially L-shaped transversal section, comprising a base portion 32 and a lateral upright portion

33, perpendicular to one another.

Supported on the base portion 32 is the wall 31 of refractory material, which has a prevalently vertical development with its back supported laterally by the upright portion 33.

The bearing frame 30 is also fitted with two profiled plates 34, of which a first profiled plate is located on the edge between the base position 32 and the upright portion 33, while a second profiled plate is at the top of the upright portion 33.

Each profiled plate 34 extends longitudinally for the entire length of the lateral flank 3, defining a hollow longitudinal channel which can serve to house, for example, the duct for the passage of the comburent air of the tunnel kiln.

The bearing frame 30 further comprises four support feet, of which two internal feet 35 and two external feet 36, these being fixed solidly under the base portion 32 and being intended to bear down on the floor.

The floor-contacting surfaces of all the support feet 35, 36 obviously lie on the same horizontal plane, which must be as close as possible to being parallel to the base portion of the bearing frame 30. As shown in figure 3, the external support feet 36 are positioned at opposite ends of the bearing frame 30, and they are reciprocally separated by an interaxis D1.

The internal support feet 35 are spaced a short distance for the opposite ends of the bearing frame 30, and they are reciprocally separated by a shorter interaxis D2.

As shown in figure 2, the external support feet 36 are reciprocally aligned in the direction of longitudinal development of the lateral flank 3, that is, in a direction parallel with the edge formed by the base portion 32 and the upright portion 33 of the bearing frame 30.

The internal support feet 35 are also aligned with each other along a direction which is parallel to the longitudinal development of the lateral flank 3, but they are displaced relative to the internal feet 36 by a distance D3.

In this way the external support feet 35 and internal support feet 36 in plan view are located substantially at the vertices of an isosceles trapezium.

As shown in figure 2, the bearing frame 30 also has a first pair of reference holes 37, which are located at one end of the upright portion 33, with horizontal axes parallel to the longitudinal development of the lateral flank 3.

These reference holes 37 are vertically aligned with each other and are located above the external support feet 36, so that their axes lie on the same vertical plain perpendicular to the base portion 32 of the lateral flank 3.

The reference holes 37 are also located at different heights relative to the floor contact surface of the external support feet 36, from which they are separated respectively by distances D4 and D5.

The bearing frame 30 also has a second pair of reference holes 37, precisely aligned with those described above, located on the opposite end of the lateral flank 3 (see fig. 3). As illustrated in figures 4 and 5, in plan view the bottom element 2 is substantially rectangular in shape, and comprises a flat base 20, preferably realized in steel elements, on which a horizontal floor 21 of refractory material of substantially constant thickness is fitted.

The flat base 20 forms a portion of the support structure 10 of the assemblable module 1 , while the floor of refractory material 21 forms a section of the refractory cladding 11.

Note that the floor and walls of refractory material 21 and 31 belonging

respectively to the bottom element 2 and the lateral flanks 3 are generally formed by panels and/or bricks of refractory material, the characteristics and reciprocal arrangement of which are well known in the practice of tunnel kiln construction, and consequently these are not described here. As shown in figure 1 , the lateral flanks 3 of the assemblage module 1 are arranged in laterally inverted positions on opposite sides of the bottom element 2.

In particular, they are positioned adjacent to the two opposite sides 22 of the bottom element 2, which have the same length as the lateral flanks 3, and they are individually covered with a mattress 23 made of insulating fibre resistant to high temperatures, interposed between the sides 22 of the bottom element and relative lateral flank 3 (fig. 1 ).

The fibre mattress 23 ensures an effective pneumatic seal between the bottom element 2 and the lateral flanks 3, allowing an airtight firing tunnel to be realised.

As shown in figure 1 , each fibre mattress 23 is covered above with a row of refractory bricks 24, which are lodged in a receiving channel 25 defined between the lateral flank 3 and the bottom element 2, and extending the full length of the module 1. This row of refractory bricks 24 screens the fibre mattress 23 from the internal environment of the firing tunnel, in order to preserve the functionality of the mattress 23 during the use of the kiln.

The side flanks 3 are fixed to the bottom element 2 by way of two pairs of projecting shelves 40, which are fixed coplanar to the bottom of the flat base 20 and project laterally from the opposite sides 22 of the bottom element 2. The projecting shelves 40 of each pair are located at the ends of the relative side 22 (see fig. 5), in order not to interfere with the internal feet 35 of the lateral flank 3, and they are spaced from the projecting shelves 40 of the other pair by a constant distance D6 (see fig. 4). As illustrated in figure 1 , the projecting shelves 40 of each pair are located at a height lower than the base portion 32 of the lateral flank 3, vertically aligned with a respective connecting plate 43 which is solidly constrained to the base

portion 32 of the lateral flank 3.

Each projecting shelf 40 is connected and fixed to the connecting plate 43 by means that will be better described herein below.

The lateral flanks 3 are also connected to each other via one or more rigid crossbars 12, which are fixed to the respective bearing frames 30, at the top of the upright portion 33 and pass above the bottom element 2.

In the present invention, the assembly of the assemblage module 1 is realized using an assembly equipment comprising a rigid structure 5 shown in figures from 6 to 8. This rigid structure 5 comprises a horizontal support frame 6, which is fitted with support feet 60 which are designed to be stably fixed to the floor.

As shown in figure 7, the support frame 6 comprises two identical longitudinal bars 61 , which lie on the same horizontal plane and are perfectly parallel and laterally inverted in relation to one another. The longitudinal bars 61 are welded to two transversal bars 62, these also parallel and laterally inverted relative to each other, coplanar with the longitudinal bars 61 and arranged transversally relative to the latter, in order to make the horizontal frame 6 rigid.

Additional rigidity of the horizontal frame 6 is provided by a pair of tie bars 63, each of which is arranged diagonally and connecting the two corner plates 64 which are welded to the ends of the support frame 6.

The longitudinal bars 61 are two steel sections of prismatic transversal section, such that the upper side of each one provides a narrow flat horizontal rest surface 65, which extends for the full length of the relative longitudinal bar 61.

Each longitudinal bar 61 comprises two distinct lateral reference elements

66, which are welded to the opposite ends of the longitudinal bars 61 , where they project vertically from the rest surface 65 (see also figs. 6 and 8).

In particular, these lateral reference elements 66 are both located on the outside edge of the rest surfaces 65, this edge being that facing the opposite direction to the transversal bars 62, and they are aligned in the direction of the axial development of the relative longitudinal bar 61 , separated by an

interaxis S1 substantially equal to the interaxis D1 that separates the external feet 36 of a lateral flank 3 (see fig. 7).

Each of the lateral reference elements 66 has a couterpart block 67, this also projecting vertically from the rest surface 65, and located on the internal edge of the rest surface 65.

The block 67 has a threaded hole into which a adjustment screw 68 is screwed, oriented horizontally, acting to move closer to or further from the reference element 66 (see figs. 10 and 11 ).

Each longitudinal bar 61 also comprises a transversal reference element 69, which is fixed to an end of the bar 61.

The transversal reference element 69 projects above the rest surface 65 of the longitudinal bar 61 , and is located substantially in the centre of the bar

61 , and is unaligned to the lateral reference elements 66 (see also fig. 10).

This transversal reference element 69 has a respective counterpart block 70, which is fixed to the opposite end of the longitudinal bar 61 , where it projects vertically from the rest surface 65 (see fig. 12).

This block 70 also has a threaded hole into which an adjustment screw 71 is screwed, oriented horizontally, acting to move closer to or further from the transversal reference element 69. As shown in figure 7, on the support frame 6 two further intermediate bars 72 of constant transversal section are fixed, these being identical to each other and welded above the transversal bars 62, in intermediate positions relative to the longitudinal bars 61.

These intermediate bars 72 are arranged laterally inverted to each other and are oriented parallel to the longitudinal bars 61 , from which they are equidistant.

The intermediate bars 72 support four identical rest plates 73, each of which is located on the end of a respective intermediate bar 72, where it is welded to the upper side of the latter. In this way the rest plates 73 in plan view are arranged substantially at the vertices of a rectangle, and they lie on the same horizontal plane, which is located higher relative to the rest surfaces 65 defined by the longitudinal bars

61 (see also figs. 6 and 8).

Each intermediate bar 72 also supports a pair of lateral reference plates 74, each of which is positioned at a respective rest plate 73, and is welded to the external side of the intermediate bar 72, the side being the one facing the nearest longitudinal bar 61.

In particular, the external surface of each pair of lateral reference plates 74 is distanced from the external surface of the reference plates 74 of the other pair by a constant distance S6 (see fig. 7), which is slightly less than the distance D6 that separates projecting shelves 40 from a bottom element 2. Finally, fixed to each intermediate bar 72, at one end only, is an axial reference pivot 75 that projects vertically from the rest plate 73. In plan view the reference pivots 75 are aligned with the reference elements 69 belonging to the longitudinal bars 61 , perpendicular to the axial development of the intermediate bars 72. As shown in figure 7, in the space between each longitudinal bar 91 and the nearest intermediate bar 72, there are a pair of horizontal shelves 76, each of which is fixed in a projecting position to a respective transversal bar 62. Each horizontal shelf 76 has a threaded hole inside which a vertical adjustment screw 77 is inserted, this oriented vertically in order to translate alternatively upwards or downwards.

In particular, the vertical adjustment screws 77 associated to a same pair of horizontal shelves 76 are aligned along a direction parallel to the longitudinal bars 61 , and they are reciprocally separated by an interaxis S2 substantially equal to interaxis D2 that separates the internal feet 36 of a lateral flank 3 (see fig. 7).

Furthermore, each adjustment screw 77 is spaced from the longitudinal bar 61 closest to it by an interaxis S3 substantially equal to interaxis D3 that separates the internal feet 36 of a lateral flank 3. As shown in figures 6 to 8, the rigid structure 5 also comprises a vertical frame 8, which is arranged precisely perpendicular relative to the longitudinal bars 61 of the horizontal support frame 6. In particular, the vertical frame 8 is located adjacent to the end of the

longitudinal bar 61 where the transversal reference elements 69 are fixed, and it is fixed rigidly to both the longitudinal bars 61 , for example with bolts. As shown in figure 6, the vertical frame 8 has two pairs of through-holes 80, each of which has its horizontal axis parallel to the longitudinal bars 61 of the support frame 6 (see fig 8).

In particular the through-holes 80 of each pair are vertically aligned above the rest surface 65 of a respective longitudinal bar 61 , and their axes are located at different heights relative to the rest surface 65, indicated respectively as S4 and S5 (fig. 6). In particular, the heights S4 and S5 are substantially equal to the respective distances D4 and D5, which separate the reference holes 37 of a lateral flank 3 from the support surface of the relative external feet 36. Each through hole 80 of the vertical frame 8 serves to receive a respective locking pin 81 (see fig. 8), which in turn is inserted into the reference holes 37 of a lateral flank 3.

As shown in figures 9a and 9b, the assembly equipment comprises a flat auxiliary frame 9, which is separated from and not attached to the rigid structure.

This auxiliary frame 9 is substantially the same shape as the vertical frame 8, in the sense that it has two pairs of through holes 90 arranged in precisely the same way as the through holes 80 of the vertical frame 8, each one of which acts to receive a locking pin 91 , which in turn inserts into the reference holes 37 of a lateral flank 3. The assembly of the assemblable module 1 device of the invention is described below.

First the rigid structure 5 is positioned for use, placing the support frame 6 on the floor, levelling it so that it is perfectly horizontal, and finally solidly fixing the support feet 60, and thus the structure, to the floor. The first phase of assembly involves the positioning of a bottom element 2 on the support frame 6, for example using a fork lift vehicle.

In particular, as shown in figures 14 and 15, the bottom element 2 is oriented with the sides 22 parallel to the longitudinal bars 61 of the frame 6; then it is

moved in the direction F, also this parallel to the longitudinal bars 61 , sliding it over a number of intermediate bars 72.

During the movement, the bottom element 2 is arranged so that the reference plates 74 associated to the intermediate bars 72 are between the projecting shelves 40 of the bottom element 2 (see fig. 13), so that the latter is correctly oriented and guided relative to the support frame 6.

As shown in figures 15 and 16, when the bottom element 2 comes into contact with the reference pivots 75, located at the ends of the intermediate bars 72, the flat base 20 is stopped and subsequently rests on the rest plates 73 which ensure that it is horizontal.

In this way, the bottom element 2 is installed on the support frame 6 in a precise and predetermined assembly position.

As shown in figure 18, the second phase of assembly involves the positioning on the support frame 6 of the lateral flanks 3, for example using a fork lift vehicle, and aligning them along the opposite sides 22 of the bottom element

2.

In this way, the fibre mattresses 23 are compressed between the lateral flanks 3 and the bottom element 2, guaranteeing an effective pneumatic seal between them. In particular, the lateral flanks 3 are positioned one after the other, moving them in opposite directions G and G', at right angles to the longitudinal bars

61 of the support frame 6.

Each lateral flank 3 is positioned so as to locate the relative external feet 36 above the rest surface 65 of a respective longitudinal bar 61 , so that the internal feet 35 are correspondingly above a pair of adjustment screws 77

(see figs. 19 and 23).

Next, the position of each lateral flank 3 is adjusted with precision on the relative rest surface 65, so that the lateral flanks 3 are perfectly aligned opposite each other, and the respective external feet 36 are aligned in reciprocally parallel directions, that is, aligned in directions parallel to the longitudinal bars 61 of the support frame 6.

For each lateral flank 3, this adjustment is achieved in the longitudinal

direction using the transversal reference element 69 and the corresponding adjustment screw 71.

As shown in figures 20, 21 , and 22, the adjustment screw 71 acts against an external foot 36 of the lateral flank 3, pushing in a longitudinal direction. This push causes the translation of the entire lateral flank 3, which stops in a predefined position when the other external foot 36 comes into contact with the transversal reference element 69 at the opposite end. In the transversal sense, the adjustment of the position of the lateral flank 3 on the rest surface 65 is instead achieved using the two lateral reference elements 66 and the relative adjustment screws 68 (fig. 23).

As shown in figure 23, each adjustment screw 68 acts against the respective external foot 36, pushing it in a transversal direction, until it comes into contact with the corresponding lateral reference element 66. Since the lateral reference elements 66 are aligned along the longitudinal bar 61 , after adjustment, the external feet 36 area also aligned along the longitudinal bar 61.

After correctly positioning the external support feet 36, the inclination of each lateral flank 3 is also precisely adjusted relative to the respective rest surface 65, so that it is exactly vertical and at right angles to the bottom element 2. As shown in figures 24 and 25, for each lateral flank 3, the adjustment of the inclination is achieved using the respective adjustment screws 77, which are located below the internal feet 35.

The vertical movement of the adjustment screws 77, and corresponding movement of the internal feet 35, causes the rotation of the lateral flank 3 relative to the external support feet 36, which are fixed in contact with the rest surface 65, thus adjusting the inclination of the lateral flank 3. In particular, the correct inclination of the lateral flank 3 is achieved when the reference holes 37 of the bearing frame 30 are perfectly aligned with a respective pair of through holes 80 in the vertical frame 8. On completion of these operations, each lateral flank 3 is fixed to the vertical frame 8 in order to maintain the adjusted inclination. This fixture is achieved using the locking pins 81 , each of which is inserted

into a reference hole 80 of the vertical frame 8 and into the reference hole 37 aligned with it in the lateral flank 3.

To ensure that the lateral flanks 3 are correctly inclined relative to the bottom element 2, the auxiliary frame 9 is fitted, this coupled with the opposite ends of the lateral flank 3, as shown in figure 27.

In particular, the reference holes 90 of the auxiliary frame 9 are aligned with the reference holes 37 in the opposite ends of the lateral flanks 3, so that each of them can receive a locking pin 91 which couples with a corresponding reference hole 37. As shown in figure 28, at the end of these operations, the bottom element 2 and the two lateral flanks 3 are each locked in a respective predefined assembly position, arranged relative to each other exactly in the positions that they must assume in the finished assemblable module 1.

The final stage of assembly is the fixing of the lateral flanks 3 and the bottom element 2, maintaining them locked in position on the rigid structure 5 in the above mentioned assembly positions, in order to obtain the completed assemblable module 1.

As shown in figure 29, fixture foresees rigid connection between the lateral flanks 3, with one or more rigid steel crossbars 12, arranged transversally, the opposite ends of which are fixed, for example with bolts or welding, to the tops of the upright portions 33 of the bearing frames 30.

The fixing stage also includes the solid fixture of each lateral flank 3 to the bottom element 2, fixing the projecting shelves 40 of the latter to the base portions 32 of the lateral flanks 3. As shown in figure 28, when the lateral flanks 3 and the bottom element 2 are in the assembly position, each projecting shelf 40 is located below the base portion 32 of a lateral flank 3, vertically aligned with a respective connecting plate 43.

The lateral flanks 3 and the bottom element 2 are designed so that, when in assembly position, a space is always formed between each projecting shelf

40 and the relative connecting plate 43.

This void permits correction of production errors of the lateral flanks 3 and/or

of the bottom element 2, without compromising the correct reciprocal positioning thereof.

The fixture of each projecting shelf 40 thus foresees the interposing of adjustable means for compensating between the projecting shelf 40 and the base portion 32, so as to precisely fill the void separating them; subsequently the projecting shelf 40 and the connecting plate 43 are tightened together with the interposed means for compensating.

In the example shown in figure 30, the means for compensating comprise a filler element 45 which is interposed between the projecting shelf 40 and the overlying connecting plate 43.

The filler element 45 can be formed from one or more superimposed metal plates, the number of which chosen as required, in order to exactly fill the void between the projecting shelf 40 and the connecting plate 43, compensating any manufacturing errors of the lateral flank 3 and the bottom element 2.

The tightening between the projecting shelf 40 and the connecting plate 43 is achieved using one or more lock screws 44, which are freely inserted in the through holes in the projecting shelf 40 and in the filler element 45 and screwed into corresponding threaded holes in the connecting plate 43. Alternatively, or in addition to the lock screws 44, solid fixture can be achieved by creating one or more welds 46 between the connecting plate 43 and the underlying projecting shelf 40.

In the alternative embodiment shown in figure 31 , the means for compensating can comprise one or more adjustment screws 47, oriented vertically screwed into corresponding threaded holes in the projecting shelf 40.

These adjustment screws 47 have a shaft that extends through the void between projecting shelf 40 and the base portion 32 of the lateral flank 3, and a head that remains positioned under the projecting shelf 40. In this way, by rotating the adjustment screws 47 the shafts come into contact with the overlying connecting plate 43 of the base portion 32, compensating the void separating the projecting shelf 40 from the connecting

plate 43.

In the case in question, tight fixture is obtained using one or more screws 48, oriented vertically, freely inserted into a hole in the projecting shelf 40 and screwing into a threaded hole in the connecting plate 43 of the base portion 32.

In this way, the screws 48 tend to pull the connecting plate 43 against the adjustment screws screwed into the projecting shelf 40, locking the lateral flank to the bottom element 2. In alternative or in addition to the locking screws 48, it is again possible to foresee the creation of one or more welds 46 directly uniting the connecting plate 43 to the projecting shelf 40.

Once the lateral flanks 3 and the bottom element 2 are correctly fixed, the assemblable module 1 is complete and can be separated from the assembly structure in order to permit the assembly of another assemblable module 1. As shown in figure 1 , between the lateral flanks 3 and the bottom element 2 two receiving channels 25 are defined, running for the entire length of the module 1 and overlying a respective fibre mattress 23. Inside each of the receiving channels 35 a corresponding row of refractory bricks 24 is arranged, covering the fibre mattress 23 relative to the internal environment of the firing tunnel, in order to preserve the functionality of the fibre mattress 23.

Obviously, with respect to the solutions proposed in the above description, a technical expert in the sector might introduce numerous modifications of technical application, without forsaking of the ambit of protection for the invention as claimed below.

In particular, it is important to note that the modular construction of the assemblable module 1 , makes it possible to interpose between the lateral flanks 3 two or more bottom elements 2, which are fixed together, in order to form assemblable modules 1 of any required width.