IT202000009433A1 - FURNACE FOR MELTING VITRIFIABLE MATERIAL - Google Patents

Description

DESCRIPTION

The present invention relates to a furnace for melting vitrifiable material.

Furnaces designed to melt vitrifiable material are known on the market.

These furnaces must reach temperatures between 1200?C and 1600?C in order to perform a correct and complete melting of the vitrifiable material whose composition can vary from time to time.

To limit the temperature to which the metal walls of the furnace are exposed can? a water cooling system must be provided for the walls themselves.

The molten vitrifiable material, when it comes into contact with the cooled metal walls, solidifies forming a crust of devitrified material that protects the metal walls themselves and provides adequate thermal insulation that allows sustainability. of the process from an energy point of view.

This protective crust must have adequate characteristics of thickness, mechanical resistance and capacity? of adhesion to the metal walls to thermally insulate the metal walls without breaking and/or detaching from them.

Any damage to the protective crust could leave the metal walls exposed to erosion by the melted material and would also have negative effects on the energy efficiency of the entire melting process.

In fact, the parts of the crust that detach and fall back into the molten bath are remelted by absorbing thermal energy which lowers the temperature of the molten mass.

A change in the temperature of the melting bath triggers a fluctuation of the parameters of the melting process which necessarily entails a deterioration of efficiency both in terms of production and in terms of energy.

The technical task proposed by the present invention is, therefore, that of realizing a furnace for melting vitrifiable material which allows the aforementioned technical drawbacks of the prior art to be eliminated.

Within the scope of this technical task, a purpose of the invention is is to create a furnace for the fusion of vitrifiable material that optimizes performance in terms of both productivity and and energy efficiency.

Another purpose of the invention? that of realizing a furnace for the melting of vitrifiable material which guarantees a uniform and long-lasting protection of the metal walls from a thermal and mechanical point of view.

Another purpose of the invention? that of creating a furnace for the melting of vitrifiable material which allows the parameters of the melting process to be kept stable.

Another purpose of the invention? that of realizing a furnace for the melting of vitrifiable material that is cheap and easy to build.

The technical task, as well as? these and other purposes, according to the present invention are achieved by realizing a furnace for melting vitrifiable material, comprising metal walls delimiting a melting tank, characterized in that each metal wall supports at least one metal pipe of cooling fluid positioned internally to said melting tank, and at least one metal anchor which extends from the outer surface of said at least one metal tube and connects said at least one metal tube to the side of said metal wall facing the inside of said melting tank.

In one embodiment of the invention said at least one tube extends for at least most of the distance between two opposite edges of said wall.

In one embodiment of the invention called at least one anchorage ? present along at least most of the length of said at least one tube.

In one embodiment of the invention said at least one anchor positions at least most of the length of said at least one pipe parallel to said metal wall.

In one embodiment of the invention said at least one anchor positions at least most of the length of said at least one pipe at a non-zero constant separation distance from said metal wall.

In one embodiment of the invention called at least one anchorage ? formed by a ribbon which extends from the external generatrix of said tube proximal to said wall and is connected orthogonally to said wall.

In one embodiment of the invention called at least one anchorage ? formed by a plurality of anchor pins distributed along at least most of the length of said at least one tube.

In one embodiment of the invention said at least one tube and said at least one anchor jointly delimit an irregular volume having recesses which assist in the formation and retention on the metal wall of a uniform protective layer of devitrified material.

In a way of realizing the invention? expected a plurality? of parallel pipes having straight lines for at least most of their length.

In a way of realizing the invention? a single coiled tube is provided.

In one embodiment of the invention said wall has a cavity where a cooling fluid circulates.

In one embodiment of the invention, the cooling fluid circuit inside said at least one tube ? connected in cascade to the refrigerant fluid circuit inside said interspace.

The use of cooling pipes projecting from the side of the wall facing the inside of the melting tank has numerous advantages.

They make it possible to optimize the thermal efficiency of the furnace in two ways.

In the first place, the distance of the pipes from the wall can? be designed in such a way as to have an optimal thickness of the protective coating crust in devitrified vitrifiable material which, being thermally insulating, in addition to protecting the pipes, prevents heat dispersion and favors the start-up phase of the furnace which ? usually very delicate.

This thickness of the crust can be increased without concrete risk that the crust may flake or detach from the walls, since, as mentioned above, the pipes and anchors jointly delimit an irregular volume presenting recesses where the devitrified material remains trapped.

The coating crust pi? thick protects the walls of the melting tank from excessive temperatures and the limitation of temperatures favors the engraftment of the vitrifiable material which devitrifies.

The thermal energy can not be disposed of only by the refrigerant fluid circulating in the pipes.

AND? in fact, it is also possible to circulate the cooling fluid inside the metal walls capable of disposing of the part of the thermal energy that propagates towards the metal walls through the metal anchors.

Therefore, extremely high temperature gradients and/or peaks are not established in the coating crust which can advantageously stay longer integrates for a long time and adheres correctly to the walls.

Secondly, the thermal efficiency of the furnace increases because? in the pipes inside the tank, the coolant can? reach temperatures pi? elevated and consequently the difference in temperature between the refrigerant fluid that circulates in the pipes and the melting tank can? be reduced.

Energy performance can be optimized by appropriately choosing the configuration and sizing of the pipes as well as the nature of the refrigerant fluid, which ? preferably but not necessarily water.

The provision of a water cooling circuit inside the melting tank offers the possibility to obtain superheated steam downstream of the heat exchange with the melting tank. Superheated steam has a vastness of uses that can significantly improve the energy efficiency of the entire process.

Further characteristics and advantages of the invention will become more evident from the description of a preferred but not exclusive embodiment of the furnace for melting vitrifiable material according to the invention , illustrated for indicative and non-limiting purposes in the attached drawings, in which:

figure 1 schematically shows an exemplifying embodiment of the furnace, in vertical section;

figure 2 shows a side elevation view of a vertical section of a vertical wall of the furnace which has horizontal pipes having an anchorage according to a first embodiment;

figure 3 shows a plan view of a horizontal section of a vertical wall of the furnace which has horizontal pipes having an anchorage according to a first embodiment; Figure 4 shows a perspective view of a pipe having an anchor according to a first embodiment;

figure 5 shows a side elevation view of a vertical section of a vertical wall of the furnace which has horizontal pipes having an anchorage according to a second embodiment;

figure 6 shows a plan view of a horizontal section of a vertical wall of the furnace which has horizontal pipes having an anchorage according to a second embodiment;

Figure 7 shows a perspective view of a pipe having an anchor according to a second embodiment;

figure 8 shows a front view of the wall of figures 2 ? 4;

Figure 9 shows a front view of a vertical wall with vertical pipes which have an anchor according to a first embodiment;

figure 10 shows a side elevation view of the vertical wall of figure 8;

figure 11 shows a front view of a wall which has a single serpentine tube with vertical coils and an anchor according to a first embodiment;

figure 12 shows a front view of a wall which has a single serpentine tube with horizontal coils and an anchor according to a first embodiment;

figure 13 shows a side elevation view of a vertical section of a vertical wall of the furnace which has horizontal pipes having an anchorage according to a first embodiment, in which the wall does not have an internal cooling circuit with a refrigerant fluid;

figure 14 shows a side elevation view of a vertical section of a vertical wall of the furnace which has horizontal pipes having an anchorage according to a second embodiment, in which the wall does not have an internal cooling circuit with a refrigerant fluid;

figure 15 shows a front view of a wall equipped with burners, with pipes having an anchorage according to a first embodiment; And

figure 16 shows a section along the line A ? A of figure 15. Equivalent parts in the various embodiments will be indicated with the same reference number.

With reference to the cited figures, a furnace for melting vitrifiable material is shown, indicated as a whole with the reference number 1.

Furnace 1 has metal walls 2i, 2ii, 2iii, 2iv, 2v delimiting a melting tank 3.

Melting tank 3 ? in particular delimited by a horizontal back wall 2i, by vertical side walls 2ii and 2iii and by inclined side walls 2iv and 2v.

The number, configuration and layout of the walls can however be different from those shown here only as an example.

In particular, figure 1 shows only two of the four vertical walls which are parallel in pairs which delimit the melting tank 3.

Above, the melting tank 3 communicates with a flue 14 for disposing of the combustion gases.

The furnace 1 has a cooling system for each of the walls 2i, 2ii, 2iii, 2iv and 2v delimiting the smelting tank 3, and possibly also for part or all of the walls forming the chimney 14.

Advantageously, the cooling system comprises, for each wall 2i, 2ii, 2iii, 2iv and 2v, one or more? metal pipes 4 of refrigerant fluid positioned inside the melting tank 3 and fixed to the wall 2i, 2ii, 2iii, 2iv and 2v by one or more? special metal anchors 5i, 5ii.

The pipes 4 and the anchors 5i, 5ii can for example be made of steel, so as well as walls 2i, 2ii, 2iii, 2iv and 2v.

Each anchor 5i, 5ii extends from the outer surface of the pipe 4 and connects it to the side of the wall 2i, 2ii, 2iii, 2iv and 2v facing the inside of the melting tank 3.

The tube 4 extends for at least most of the distance between two opposite edges of the wall 2i, 2ii, 2iii, 2iv and 2v.

In the illustrated solution, for the walls 2i, 2ii, 2iii, 2iv and 2v which have a substantially parallelepiped configuration, the pipe 4 extends for at least most of the distance which separates two parallel edges of the walls 2i, 2ii, 2iii, 2iv and 2v themselves.

The anchors 5i, 5ii are provided along at least most of the length of the pipe 4.

The anchors 5i, 5ii position at least most of the length of the pipe 4 parallel to the wall 2i, 2ii, 2iii, 2iv and 2v.

Preferably the anchors 5i, 5ii position at least most of the length of the pipe 4 at a non-zero constant separation distance from the wall 2i, 2ii, 2iii, 2iv and 2v. The 5i docking in a first embodiment ? formed by a ribbon which extends from the external generatrix of the tube 4 proximal to the wall 2i, 2ii, 2iii, 2iv and 2v and is connected orthogonally to the wall 2i, 2ii, 2iii, 2iv and 2v.

In this case the band has a first longitudinal edge joined without interruption to the tube 4 and a second longitudinal edge joined without interruption to the wall 2i, 2ii, 2iii, 2iv and 2v.

The conjunction? preferably made by welding.

The 5ii anchor in a second embodiment ? formed by a plurality of anchor pins distributed along at least most of the length of the pipe 4.

Furthermore, the anchor pins are preferably distributed in groups which follow one another at a constant pitch.

For example, the assemblies are formed with three anchor pins which have different inclinations.

Preferably a first pivot ? connected orthogonally to wall 2i, 2ii, 2iii, 2iv and 2v and radially to pipe 4.

The second and third pins, on the other hand, are oblique, they join wall 2i, 2ii, 2iii, 2iv and 2v on the opposite side of the first pin and converge towards the first pin in the direction that goes from wall 2i, 2ii, 2iii, 2iv and 2v to tube 4.

Advantageously, the pipes 4 and the anchors 5i, 5ii delimit in cooperation an irregular volume having recesses 6i, 6ii which assist in the formation and retention on the wall 2i, 2ii, 2iii, 2iv and 2v of a uniform protective layer of devitrified material 7. In this way can you? increase the distance of the pipes 4 from the walls 2i, 2ii, 2iii, 2iv and 2v to increase the thickness of the layer of devitrified material 7 and consequently improve the thermal insulation of the melting tank 3 without risk of detachment or flaking or breakage of the layer of devitrified material 7.

In particular you can provide a fixed distance of between 5 and 15 cm between the center of the pipe 4 and the wall 2i, 2ii, 2iii, 2iv and 2v.

Also the thickness and the internal diameter of the pipes 4 can? be suitably designed to ensure optimal heat exchange conditions.

In some cases ? preferable to provide a plurality? of straight parallel pipes 4 for at least most of their length.

With reference to the vertical walls 2ii, 2iii, these pipes 4 can have a horizontal or vertical arrangement, while with reference to the oblique walls 2iv, 2v, these pipes 4 can have a horizontal or oblique arrangement with the flow directed upwards.

These pipes 4 can be fed in parallel through an inlet manifold 8 and an outlet manifold 9.

The inlet manifold 8 and the outlet manifold 9 are preferably positioned externally to the side of the wall 2i, 2ii, 2iii, 2iv, 2v facing away from the melting tank 3.

In this case, these pipes 4 have at their ends opposite of the corner fittings 10i, 10ii for connection to the manifolds 8, 9 which pass through the wall 2i, 2ii, 2iii, 2iv, 2v.

The corner fittings 10i, 10ii are preferably 90° bends. In other cases? it is preferable to provide a single coiled tube 4. The coiled tube 4 can? have straight sections connected by 180° curves.

With reference to the vertical walls 2ii, 2iii, this pipe 4 can? have the straight sections with a horizontal or vertical arrangement, while in reference to the oblique walls 2iv, 2v such tube 4 pu? have a horizontal or oblique arrangement.

This tube 4 at the ends? opposite can? have angular terminals, preferably 90? bends, which cross the wall 2i, 2ii, 2iii, 2iv, 2v.

Wall structure 2i, 2ii, 2iii, 2iv, 2v can also? have variations.

In certain cases ? It is possible to provide a wall 2i, 2ii, 2iii, 2iv, 2v inside which a cooling fluid circulates, as clearly visible in figures 2, 3, 5 and 6.

In these cases can a cavity 11 must be provided inside the walls 2i, 2ii, 2iii, 2iv and 2v of the melting tank 3.

In these cases the walls 2i, 2ii, 2iii, 2iv and 2v of the melting tank 3 can each be formed by an internal panel 12 facing the molten material present in the melting tank 3 and an external panel 13 positioned on the opposite side to the molten material present in the melting tank 3. The internal panel 12 and the external panel 13 delimit the interspace 11 for the circulation of the refrigerant fluid. The cavity 11 preferably has baffles 15 which, in addition to spacing the panels 12, 13, guide the cooling fluid along a fixed path.

The refrigerant fluid circuit inside the pipes 4 can? be connected in cascade to the refrigerant fluid circuit inside the interspace 11, or it can? be independent. In the first case, the preheated cooling fluid in the first cooling circuit is fed into the second cooling circuit with a consequent improvement in the energy performance of the process.

In other cases? It is possible to provide a wall 2i, 2ii, 2iii, 2iv, 2v inside which no cooling fluid circulates, as clearly visible in figures 13 and 14.

The furnace 1 has burners 16 which can be installed from below, on one side or even from above the melting tank 3.

The 5i anchorage conforms to the first embodiment ? particularly convenient if provided on the wall 2i, 2ii, 2iii, 2iv, 2v where the burners 16 are installed.

In fact, the tape surrounds the burners 16, preventing gas bubbles from penetrating into the depths of the burners. between the metal wall 2i, 2ii, 2iii, 2iv, 2v where they are installed and the layer of devitrified vitrifiable material 7.

This avoids triggering an irreversible delamination process which would lead to the detachment of the layer of devitrified vitrifiable material 7.

In figure 15 we also appreciate that, to block more? effectively the diffusion of the gas bubbles from the burner 16 in all possible directions grazing the wall, one can? fix an additional piece of metal tape to the wall which, in cooperation with the anchor 5i, completely surrounds the burner 16.

In this case, optionally, the additional piece of metal tape can be coupled to an additional section of metal cooling pipe which defines a branch of the cooling fluid circuit.

In a variant, the additional piece of tape can? in turn be coupled to a piece of pipe which connects

AND? clear that the construction variants of the furnace are intended to enhance specific functionalities? compared to others.

For example, the prediction of pi? cooling pipes in parallel, increasing the heat exchange volumes, determines an increase in the thermal energy disposed of, while the provision of a single cooling pipe, reducing the heat exchange volumes, determines an increase in the enthalpy of the outgoing cooling fluid which can? then be employed for a variety? more wide of applications.

The provision of an anchorage of the first type improves the transmission of thermal energy by conduction towards the furnace wall, while the provision of an anchorage of the first type lightens the overall structure but limits the transmission of thermal energy by conduction towards the furnace wall.

The provision of a bundle of vertical pipes favors a more? homogeneous thermal power dissipated which does not depend on the level of the molten material in the melting tank.

In fact, as the level of molten material varies, the ratio between the immersed portion and the emerged portion varies identically for all the pipes. The provision of a bundle of horizontal pipes, on the other hand, takes into account a differentiated distribution of the thermal power disposed of between the pipes below and above the level of the molten material in the melting tank.

The coolant can be water or other fluid, for example at a higher evaporation temperature than water.

Finally, each wall of the furnace can present, depending on the needs, a distribution and configuration of the cooling pipes and of the anchors different from what is illustrated and described.

For example there could be a first bundle of coplanar pipes at a first distance from the wall and a second bundle of coplanar pipes at a second distance different from the first from the wall, with the pipes of the first bundle interspersed between the pipes of the second bundle.

Nor is it excluded that at least some of the anchors may in turn have internal channels for the circulation of a cooling fluid.

In that case can a fluid connection be provided between the cooling pipes and the anchors, and possibly a fluid connection between the anchors and the cavity, if any, of the furnace wall.

The furnace for melting vitrifiable material is so? conceived ? susceptible to numerous modifications and variations, all falling within the scope of the inventive concept; moreover all the details can be replaced by technically equivalent elements.

In practice, the materials used, as well as? the dimensions may be any according to the requirements and to the state of the art.

Claims (12)

1. Furnace (1) for melting vitrifiable material, comprising metal walls (2i, 2ii, 2iii, 2iv, 2v) delimiting a melting tank (3), characterized in that each wall (2i, 2ii, 2iii, 2iv, 2v) supports at least one metal tube (4) of cooling fluid positioned inside said melting tank (3), and at least one metal anchor (5i, 5ii) which extends from the outer surface of said at least one metal tube (4) and connects said at least one metal tube (4) to the side of said wall (2i, 2ii, 2iii, 2iv, 2v) facing the inside of said melting tank (3). 2. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that said at least one tube (4) extends for at least most of the distance between two opposite edges of said wall (2i, 2ii, 2iii , 2iv, 2v). 3. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that said at least one anchor (5i, 5ii) ? present along at least most of the length of said at least one tube (4). 4. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that said at least one anchor (5i, 5ii) positions at least most of the length of said at least one pipe (4) parallel to said wall ( 2i, 2ii, 2iii, 2iv, 2v). 5. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that said at least one anchor (5i, 5ii) positions at least the greater part of the length of said at least one tube (4) at a separating distance non-zero constant from said wall (2i, 2ii, 2iii, 2iv, 2v). 6. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that said at least one anchor (5i) ? formed by a ribbon which extends from the external generatrix of said tube (4) proximal to said wall (2i, 2ii, 2iii, 2iv, 2v) and is connected orthogonally to said wall (2i, 2ii, 2iii, 2iv, 2v). 7. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that said at least one anchor (5ii) ? formed by a plurality of anchor pins distributed along at least most of the length of said at least one tube (4). 8. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that said at least one tube (4) and said at least one anchor (5i, 5ii) delimit in cooperation an irregular volume (6i, 6ii) having recesses which assist in the formation and retention on the wall (2i, 2ii, 2iii, 2iv, 2v) of a uniform protective layer of devitrified material (7). 9. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that it comprises a plurality of straight parallel pipes (4) for at least most of their length. 10. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that it comprises a single serpentine tube (4). 11. Furnace (1) for melting vitrifiable material according to claim 1, characterized in that said wall (2i, 2ii, 2iii, 2iv, 2v) has an interspace (11) where a cooling fluid circulates. 12. Furnace (1) for melting vitrifiable material according to the preceding claim, characterized in that the cooling fluid circuit inside said at least one tube (4) is? connected in cascade to the refrigerant fluid circuit inside said interspace (11).