SEALING

The present invention relates to a sealing tube for a door to an industrial furnace. The invention also relates to a sealing device for a vertically opened door to an industrial furnace, where the sealing device comprises such a sealing tube.

Today, industrial furnaces are used to heat various materials, such as different metals, ceramics, etc. In order to avoid unnecessary thermal losses during operation, openable doors into the industrial furnaces are used, which are closeable when no material for the moment needs to be transported into or out from the furnace. Such doors are generally vertically arranged, and are consequently opened or closed using a vertical motion of the door. In general, the door is opened by raising it and closed by again lowering it.

A problem during operation of such doors is that it is difficult to achieve a satisfactory sealing between the moving door and the industrial furnace. Such a sealing is desirable in order to avoid thermal losses, leakage in of air and leakage out of flue gases, etc. Because of the high temperatures and the potentially chemically aggressive gases in the industrial furnace, it is difficult to find sealing materials with sufficiently long useful lives in the inhospitable environment around the edge of the door.

The Swedish patent application 0700628-1 discloses the use of water-filled tubes for sealing one of the vertical side edges of a vertically displaceable door, through which tubes a side edge of the door runs. Such a design solves the problem with reliable and cost-efficient sealing of the edges of the door, but sealing problems along the upper and lower edges of the door remain. Since the pressure in a hot industrial furnace varies, to an extent which is not negligible, with the height above the furnace floor, leakinesses at the upper edge of the door result in particularly severe difficulties to maintain the desired pressure in the furnace as well as good fuel economy and energy efficiency.

Thus, these problems are present when the door is closed, but also when the door is partly open. Namely, a door which is opened by raising it upwards results in that the opening into the furnace extends from the lower edge of the door opening and upwards to the lower edge of the door in a partly opened state of the door. As long as full sealing can be guaranteed at the upper edge of the door, even in case the door is partly open, the gas exchange between the furnace and the environment, which is smaller further down in the furnace as a consequence of the lower pressure there, will be limited.

The present invention solves the above described problems.

Thus, the present invention relates to a sealing tube for a door for an industrial furnace, which tube is adapted to be mounted vertically and to be filled with a liquid coolant, where the tube comprises an upper end arranged to face upwards when the tube in mounted, and an opposite lower end, where the tube furthermore comprises a first longitudinal opening, arranged to receive a side edge of the door, and thereby accommodate the side edge slidably along the direction of elongation of the tube, and where the tube is arranged to sealingly connect to the side edge of the door when the tube is so filled with the coolant so that the coolant essentially fills the space which in the cross-section of the tube perpendicularly to its direction of elongation is defined by the combi- nation of the inner surfaces of the tube and the outer surfaces of the door around the side edge, and is characterised in that the tube, in addition to the first longitudinal opening, also comprises a second longitudinal opening, arranged to run from the upper end of the tube and a certain distance towards the lower end, in that the first longitudinal opening runs further down towards the lower end than does the second longitudinal opening, in that the upper end of the tube is open between the respective orifices, in the upper part of the tube, of the two longitudinal openings, and in that the second longitudinal opening is arranged to receive and accommodate, slidably in the direction of elongation of the tube, an elongated, vertical sealing part of the door, which is inserted into the second longitudinal opening along the direction of elongation of the tube from the upper end of the tube.

In the following, the invention will be described in closer detail, partly in connection to embodiments of the invention, and with reference to the appended drawings, where:

Figure 1 is a simplified perspective view of a part of a first preferred door sealing device according to the present invention, comprising a sealing tube according to the invention;

Figure 2 is a simplified perspective view of the door sealing device according to figure 1 as viewed from the right side in figure 1;

Figures 3-5 are simplified perspective top views of the door sealing device of figure 1, where the upper part of the door sealing device is removed at the horizontal cut A, B and C, respectively, in figure 1;

Figure 6 is a simplified perspective view of a second preferred door sealing device according to the present invention, comprising a sealing tube according to the invention, in the form of an explanatory sketch;

Figure 7 is a simplified perspective view from the right of the door sealing device of figure 6, where the right part of the door sealing device is removed at the vertical cut D;

Figures 8-10 are simplified perspective top views of the door sealing device of figure 6, where the upper part of the door sealing device is removed at the horizontal cut E, F and G, respectively, in figure 6; and

Figures 11-12 are two perspective views, from the right and to the left, respectively, of the door sealing device according to figure 1, where the door is partly opened.

Figures 1-5 and 6-10, respectively, illustrate corresponding views of the two preferred embodiments, and the same reference numerals are used for corresponding parts. The door sealing device illustrated in figures 1-5 shows, for clarity reasons, only one of the halves (the left half in figure 1) of the sealing device, where it is realized that the other half advantageously can be essentially mirror symmetric in relation to the shown half.

The door sealing device illustrated in figures 6-10 is a very simplified explanatory sketch, the purpose of which is to illustrate the principle of the present invention. The door sealing device illustrated in figures 1-5 is more detailed than the explanatory sketch, but is also simplified, and the dimensions in both figures are partly exaggerated in order to increase clarity in the figures.

In the following, the door sealing device is described only with reference to one of its halves, and it is realized that corresponding properties can be ascribed also to the other half.

Figures 11-12 show the same partly removed door sealing device as figures 6-10, but with the door raised from a completely closed position to a partly open position.

An industrial furnace 100 is, in one of its side walls, provided with a through opening 110 for bringing material into or out from the furnace 100. A vertically arranged and openable door 200 is arranged to sealingly cover the through opening 110. The door 200 is opened by bringing it upwards, and is again closed by lowering it back to its original position. The door 200 is shown in figures 1-10 in a closed position and in figures 11-12 in a partly opened position.

The door's 200 connection to the furnace 100 is preferably arranged to be tight-fitting around its whole periphery, that is along the side edge 201 of the door 200, its upper edge 202 and its lower edge 203, with the help of a door sealing device 300 according to the present invention.

The door sealing device 300 comprises a vertically arranged sealing tube 310, in which the vertical side edge 201 of the door 200 is arranged to be received and along which the side edge 201 is arranged to slidably run. This is clearest shown in figures 4, in which the sealing tube 310 is designed as a circular cylinder, and 9, in which the tube 310 is in the form of a cavity in the shape of a rectangular parallelepiped in the wall of the furnace 100. Preferably, the sealing tube 310 extends at least along essentially the complete length of the side edge 201 when the door 200 is in a closed position, and essentially along the whole side edge 111 of the opening 110. The sealing tube 310 is provided with a first longitudinal opening 314, 318, preferably and as illustrated in figures 1-5 in the form of a slit running from an upper end 311 of the sealing tube 310, which end 311 is arranged to face upwards, and downwards when the sealing tube 310 is mounted for operation as a part of the sealing device 300.

Then, the side edge 201 of the door 200 is inserted into the sealing tube 310 through the slit 314, 318, and is therein arranged to be completely surrounded by the tube 310 when the door 200 is in a closed position. When the door 200 is opened or closed, its side wall 201 runs inside the tube 310 in the longitudinal, vertical direction of the tube 310.

Herein, the expression "vertical", as it is used for describing the sealing tube 310, the side edge 201 of the door 200 and so on, refers to a spatial orientation which is essentially vertical. In other words, a vertically arranged part does not have to be absolutely plumb, but can have a certain horizontal directional component, as long as the orientation is sufficiently vertical in order to allow that an elongated water column can be present for sealing purposes in or in connection to the vertically arranged part, see below. In other words, the opening 110 of the furnace 100 can be somewhat inclined, as long as it has a vertical component which is larger, preferably substantially larger, than its horizontal component .

A circulation device (not shown) for liquid coolant is arranged to continuously cause coolant 370, which is shown in figures 6-10 but not in figures 1-5 and 11-12, to flow through the tube 310, by supplying coolant 370 at a supply location, preferably to the tube 310 or to an upper tray 350 (see be- low) , and preferably in level with or above the upper end 311 of the tube 310 in the direction of gravity. Moreover, it is preferred that a lower tray 360, positioned straight below the lower end 312 of the tube, opposite to the upper end 311, is arranged to collect the coolant 370. The coolant is arranged to flow through the lower end 312, and the circulation device is furthermore and preferably arranged to bring back the coolant 370 to the supply location using a pump (not shown) , which pump is conventional as such.

According to a preferred embodiment, the tube 310 is designed to spring back towards a position in which the slit 314, 318 is closed. The spring action of the tube 310 can be achieved by the tube 310 itself being designed in a resilient material, or comprising spring means (not shown) , leading to the tube 310 springing back towards a position in which the slit 314, 318 is closed.

Alternatively, and as is shown in figure 1-5, the tube 310 however comprises an outer tube 317, manufactured from a rigid material, preferably metal, and an inner tube 313, manufactured from a flexible material. The outer tube 317 and the inner tube 313 are preferably concentrically arranged. The inner tube 313 furthermore comprises an longitudinal slit 314, corresponding to the longitudinal slit 318 along the outer tube 317 and together with the slit 318 arranged to receive and accommodate the side edge 201 of the door 200.

Such a construction results in a robust and heat resistant yet simple and therefore cost-efficient solution.

The construction which is shown in figures 6-10 only comprises one tube 310, without any inner tubes. Preferably, the inner tube 313 is manufactured from a resilient material, for example in the form of a thick rubber tube with the slit 314 as a longitudinal and through cut.

However, according to a preferred embodiment, the outer diameter of the flexible tube 313, when the tube 313 is in a state of rest, is larger than the inner diameter of the outer tube 317, and the edges 315 of the flexible tube 313 at the slit 314 are bent or folded in towards the centre of the outer tube 317 when it is mounted in the outer tube 317 and when the side edge 301 is inserted through the slits 314, 318, which folded- in edges 315 achieve the above mentioned spring action. This results in a very good sealing during operation, as described below .

According to a particularly simple and therefore preferred embodiment, the flexible tube 313 is designed as a mat or sheet of flexible material, advantageously wider than the inner circumference of the outer tube 317, which mat in a state of rest is substantially plane but which is rolled to a tube shape when mounted in the outer tube 317.

It is also possible to supplement an outer tube which is resilient as such with an inner, flexible tube 313 according to the above.

According to the invention, the circulation device is arranged to achieve continuous flowing of the coolant 370 through the outer tube 317, so that the coolant 370 essentially fills the space which in the cross-section of the tube 310 is defined by the combination of the inner surfaces of the tube 310 and the outer surfaces, around the side edge 201 of the door 200. In case several tubes are used one inside the other according to the above said, for example an inner, flexible tube 313 in combination with an outer, rigid tube 317, the coolant 370 is arranged to flow through the inner or innermost tube 313 and essentially fill the complete space between the inner surfaces of this tube and the outer surfaces of the side edge 201.

According to a preferred embodiment, the coolant 370 is water, but can be any suitable liquid coolant, such as water with a suitable, conventional, friction-decreasing and/or abrasion- decreasing additive, or a suitable, conventional, liquid low friction coolant.

The circulation device is arranged to continuously drain the coolant 370 off and away from the tube 310 by the use of gravity, for example via leakage from the tube 310 through the slit 314, 318 or through leakinesses or other openings in the tube 310.

Since the coolant 370 continuously flows through the tube 310, the tube is more efficiently cooled during operation, and it is therefore possible to achieve a satisfying useful life for the tube 310. Moreover, the spring action of the tube 310 back towards the position in which the slit 314, 318 is closed ensures that the slit 314, 318 seals tight-fittingly around the outer sides of the side edge 201. That the slit 314, 318 "seals tight-fittingly" shall herein be construed to mean that no gas can pass through the slit 314, 318 when the tube 310 is filled with coolant 370 at least up to a certain level 371 in the tube 310. The level 371 is controlled, by the circulation device, so that it is sufficiently high in order to achieve adequate sealing according to the invention. The coolant 370, on the other hand, can leak out through the slit 314, 318 to a certain extent as long as the level 371 can be maintained despite the leakage. According to a preferred embodiment, the lower end 312 is provided with a flow valve (not shown) , which is continuously controlled by the circulation device for controlling the liquid level 371.

The tube 310 is tight-fittingly fastened to the outer wall of the industrial furnace 100 using sealing fastening means 320. Furthermore, an overpressure arises inside the tube 310 because of the liquid column of coolant inside the tube 310, leading to the volume between the inner surfaces of the tube 310 in combination with the outer surfaces of the door 200 side edge 201 always being filled with coolant during operation. Thereby, efficient sealing is achieved between the side edge 201 of the door 200 and the side edge 111 of the opening 110 in the furnace 100.

Since the tube 310 is arranged to spring back towards a position in which the slit 314, 318 is closed, the liquid column in the tube 310 will be maintained even along the parts of the tube 310 below the side edge 201 of the door 200 along which the side edge 201 of the door 200 does not extend when the door 200 is completely of partly opened.

According to the present invention, the tube 301 comprises, in addition to the first longitudinal opening 314, 318, also a second longitudinal opening 316, 319, running from the upper end 311 and a certain distance downwards towards the lower end 312. Both longitudinal openings 314, 318; 316, 319 run all the way up to, and open out in, the upper end 311. The first longitudinal opening 314, 318 is arranged to run further down towards the lower end 312 than the second longitudinal opening 316, 319, preferably all the way from the upper end 311 and onwards to, and opening out in, the lower end 312. Moreover, it is preferred that the vertical distance between the termination of the first longitudinal opening 314, 318 downwards and the corresponding termination downwards of the second longitudinal opening 316, 319 is larger than the height of the opening 110. Furthermore, the upper end 311 of the tube 310 is at least partly open, especially in connection to the opening in the upper end 311 of the two longitudinal openings 314, 318; 316, 319, and especially so that both openings are connected to each other by the use of an opening in the upper end 311 of the tube 310 so that a sealing part in the form of a piece of sheet metal can be brought down into the tube 310 and the two longitudinal openings 314, 318; 316, 319 from above when mounted for operation via said opening in the upper end 311.

As illustrated in the figures, and as is the case for the first longitudinal opening 314, 318, the second longitudinal opening 316, 319 is arranged as a radial through opening through the tube 310, that is through all tubes 313, 317 which are arranged one inside of the other.

According to the invention, the second longitudinal opening 316, 319 is further arranged to receive and slidably, in the longitudinal direction of the tube 319, accommodate an elongated, vertical sealing part 204 of the door 200, which sealing part 204 can be inserted into and accommodated in the second longitudinal opening 316, 319 along the longitudinal direction of the tube 310 from the upper end 311 during mounting of the door 200. Such insertion is also enabled by the second opening 316, 319 opening out in the upper end 311, which is at least partly open, as described above. The second longitudinal opening 316, 319 can, in cross- section, be similar to the first longitudinal opening 314, 318. However, the tube 310 is preferably not arranged to spring back towards a position in which the second longitudinal opening 316, 319 is closed. According to a preferred embodiment, the second opening 316, 319 is designed as a longitudinal cut-out in the tube 310, which is so wide so that it, with margin, can receive the vertical sealing part 204. In other words, the lower part of the sealing part 204 is arranged to be surrounded by coolant 370 when it runs through the second longitudinal opening 316, 319.

As is best shown in figures 2, 3, 7 and 8, the second opening 316, 319 is adapted to be connected to an upper tray 350 for coolant 370, so that a liguid connection 351 is accomplished between the upper tray 350 and the tube 310, via the second opening 316, 319. When the coolant 370 level 371 in the tube 310 and/or the upper tray 350 is sufficiently high, the coolant can thereby form a connected body which is common for the tube 310 and the upper tray 350. Such a connected body of coolant 370 can for example be accomplished by continuously sup ^¬ plying coolant 370 to the upper tray 350 and thereafter allowing it to flow from the upper tray 350, via the liquid connection 351 and down into the tube 310, so that the coolant 370 level in both the upper tray 350, the liquid connection 351 and the tube 310 can be maintained constant. Alternatively, the upper tray 350, the liquid connection 351 and the tube 310 can share a common liquid surface of coolant, having the same level everywhere but which surface in itself may be connected or fragmented, whereby the tray 350, the connection 351 and the tube 310 form communicating vessels.

By the use of such a sealing tube 310, a sealing connection between on the one hand a substantially horizontal, upper seal between the upper edge 202 of the door 200 and the furnace 100, and on the other hand a substantially vertical seal between the side edge 201 of the door 200 and the furnace 100, can be achieved, since a side edge 335 of a part of the sealing means of the door 200 for its upper edge 202 can be arranged so that it runs into the tube 310 through the second longitudinal opening 316, 319 and so that it connects to the side edge 201 of the door 200 in the environment inside the tube 301, which environment is sealing because of the coolant 370, whereby the parts of the door 200 that seal the upper edge 202 and the side edge 201, respectively, of the door 200 to the furnace 111, as well as the connection between said edges 201, 202, completely run through a connected body of coolant 370. This is described in closer detail in the following .

A door sealing device 300 according to the present invention for the connection of the door 200 to the opening 110 thus comprises a sealing tube 310 according to the above. It is realized that the sealing device 300 in the normal case comprises a sealing tube 310 at both sides of the door 200, which is illustrated in figures 6-10. When the tube 310 is sufficiently filled with coolant, the door 200 is sealed to the furnace 100 by its side edge 201 running within and along the tube 310 as described above.

Moreover, according to the invention the sealing device 300 comprises the upper tray 350, which is arranged above the upper edge 112 of the opening 110, and is furthermore sealingly connected to the furnace 100, as well as to a U-shaped projection 330, which is sealingly connected to the door 200 and comprises a first part 331 extending upwards from the door 200 and a second part 333 extending downwards. When the door 200 is in a closed, that is completely lowered, position, and the upper tray 350 is sufficiently filled with coolant 370, a lower edge 334 of the second part 333 is arranged to run below the level 371 for, and completely be surrounded by, coolant

370 in the upper tray 350. Thereby, a sealing connection between the door 200 and the furnace 100 along the entire upper edge 112 of the opening can be achieved.

The sealing device 300 also comprises the liquid connection 351 between the upper tray 350 and the tube 310, via the second longitudinal opening 316, 319 of the tube 310, which connection 351 is arranged to allow that the coolant 370 is common for the upper tray 350 and the tube 310 when both of these are sufficiently filled with coolant, as described above .

As can best be seen in figures 3 and 8, respectively, the sealing device 300 also comprises a connection 336 between the second part 333 of the U-shaped projection 330 and the side edge 201 of the door 200, which constitutes the vertical sealing part of the door 200 since it runs within and along the tube 310. The connection 336 is arranged to be located partly below the liquid level 371 for the coolant 370, when the upper tray 350 and the tube 310 are sufficiently filled with coolant and the door 200 is also closed. The part of the connection 336 which in this position is arranged above the liquid level

371 in the tube 310 is arranged to sealingly connect the second part 333 of the projection 330 to the side edge 201 of the door 200. Since the part of the connection 336 which is arranged below the liquid level 371 will be sealing because of the coolant 371, the complete connection 336 will also be sealing . According to the preferred embodiment illustrated in figure 3, the first 331 and second 333 parts of the U-shaped projection, the upper part of the side edge 201 of the door 200 and the connection 336 constitute a single, connected wall, running in parallel to and along the upper edge 202 of the door, across the tube 310 via the first 314, 318 and second 316, 319 longitudinal openings and back, in parallel with and along the upper edge 202 of the door 200. In this case, the first part 331 of the U-shaped projection 330 in fact constitutes, at its side edge 332, the upper part of the side edge 201 of the door 200.

According to the preferred embodiment illustrated in figure 8, the first part 331 of the U-shaped projection 330 in fact consists of the upper part of the door 200, which thus constitutes a part of a connected wall corresponding to the embodiment illustrated in figure 3, and which also comprises the second part 333 of the U-shaped projection 330 as well as the connection 336.

Hence, this connected wall runs across the tube 310, in a plane which is perpendicular to a diameter of the tube 310, via the two longitudinal openings 314, 318; 316, 319, which openings thus are arranged at two different angular positions in the tube 310. The connected wall is provided with a roof part 340, see figures 1, 2, 6, 7. The roof part 340 is sea- lingly connected to both the first 331 and the second 333 parts of the U-shaped projection 330 and to the connection 336, and is arranged to sealingly connect to on the one hand the sealing between the side edge 201 of the door 200 and the tube 310, and on the other hand the sealing between the second part 333 of the U-shaped projection 330 and the upper tray 350 when the door 200 is closed and the upper tray 350 and the tube 310 are sufficiently filled with coolant 370.

The latter sealing is achieved by the above described, connected wall and the roof part 340 together form a sealing, hood-like structure. Since the second part 333 of the U-shaped projection 330 runs along the upper tray 350 below the level 371 for the coolant 370 and on, all the time below said level 371, into the tube 310, and there connects to the side edge 201 of the door 200 via the connection 336, which side edge 201 in turn continues downwards along the tube 310, all the way surrounded by coolant 370, no gas will be able to leak into or out from the hood structure, via neither the horizontal sealing, the vertical sealing, nor the connection between these two respective sealings.

As is clearest illustrated in figures 1 and 6, according to a preferred embodiment the first 331 and the second 333 part, respectively, of the U-shaped projection 330 are connected to each other by the connection 336 both inside the tube 310 itself and also partly in the extension of the tube 310 outside of the tube 310 above its upper end 311. In other words, the roof part 340 is arranged outside and above the tube 310.

In the preferred case in which the door sealing device 300 comprises two sealing tubes, each arranged to sealingly connect a respective side edge of the door 200 to the furnace 100, the upper tray 350, the roof part 340 and the U-shaped projection 330 are preferably common to both tubes. Thereby, the above described, connected wall will, as seen from above in the figures, form a closed curve, which is tight-fittingly closed by the roof part 340. This is most clearly shown in figure 6. Thus, a sealing hood is formed, which efficiently seals all edges of the door 200 to the furnace 100, except possibly between the lower edge 203 of the door 200 and the lower edge 113 of the opening 110.

This sealing is, according to the above, efficient as long as the liquid level 317 for the coolant 370 is sufficiently high and as long as the door 200 is in its closed position. According to yet another preferred embodiment, the upper tray 350 is however sufficiently deep, and both the second part 333 of the U-shaped projection 330 and the sealing part of the connection 336 between the second part 333 of the U-shaped projection 330 and the side edge 201 of the door 200 are sufficiently tall, in order for the edge 334 of the second part 333 of the U- shaped projection 330 to be completely immersed in the coolant 370 in the tray 350, and in order for the part of the connection 336 which is arranged above the liquid level 371 for the coolant 370 in the tube 310 to sealingly connect the second part 333 of the U-shaped projection 330 to the side edge 201, for all positions of the door 200 from completely closed to sufficiently opened for full access to the opening 110 in the furnace 100, all on condition that the tube 310 and the upper tray 350 are sufficiently filled with coolant 370.

The effect of such an arrangement is most easily understood from figures 11 and 12, in which the door 200 is shown in a partly opened position. From figure 12, it is clear that the part of the connection 336 which is arranged above the liquid level 371 and sealingly connects the second part 333 of the U- shaped projection 330 to the side edge 201 of the door 200 is in the form of an all-covering, tight-fitting wall. When the door 200 is closed, this tight-fitting wall is thus brought downwards along the tube 310, and along the two longitudinal openings 314, 318; 316, 319, as described above. From the cross-section shown in figure 12, it is clear that the second part 333 of the U-shaped projection 330 is still arranged partly in the upper tray 350, notwithstanding that the door 200 has been opened in relation to its closed position. In order to adapt the sealing device 300 for sealing connection for a certain largest opening of the door, a sufficient depth is selected for the upper tray 350 and a sufficiently tall height for the connection 336.

This way, adequate sealing can thus be achieved along all edges of the door 200, possibly except at the lower edge 203 of the door 200, even if the door 200 is completely or partly opened. Thereby, problems with leakage during opening of the door can be decreased, since the gas pressure inside the furnace 100 is higher further up in the furnace 100 and therefore constitutes a smaller problem below the lower edge 203 of the door 200.

Moreover, according to a preferred embodiment the lower edge 203 of the door 200 is arranged to, when the door 200 is being closed, be brought down into the lower tray 360 to a position below the liquid level therein, so that a sealing connection between the lower edge 203 of the door 200 and the furnace 100 is achieved when the door 200 is in its closed position and the lower tray 360 is sufficiently filled with coolant 370. This thus achieves a sealing even along the lower edge 203 of the door 200. The liquid level in the lower tray 360 is controlled in a way which is conventional as such, using the circulation device, for example using a flow valve (not shown) for discharge near the bottom of the lower tray 360.

According to an especially preferred embodiment, which is clearest illustrated in figures 5 and 10, respectively, in the position in which the lower tray 360 is sufficiently filled with coolant 370, the lower end 312 of the tube 310 is arranged in the lower tray 360 as far down so that the end 312 is completely immersed in the coolant. Since the coolant 370 continuously flows down through the tube 310 and out into the lower tray 360, this will result in that the tube 310 is sea- lingly connected to the lower tray 360. Furthermore, the lower edge 203 of the door 200 connects to a lower end of the side edge 201 of the door 200, so that a sealing connection is achieved between on the one hand the sealing between the side edge 201 of the door 200 and the tube and on the other hand the sealing between the lower edge 203 of the door 200 and the lower tray 360. This way, when the door 200 is completely closed, a complete seal of all the edges of the door 200 in relation to the furnace 100 is thus achieved.

In other words, in the above described way the sealing device 300 achieves a complete seal of the door 200, so that atmospheric air cannot leak into the industrial furnace 100 and so that furnace atmosphere gases cannot leak out from the furnace 100.

Above, the present invention has been explained with reference to exemplifying embodiments. However, it is realized that the invention is not limited to the described embodiments, but may be varied within the scope of the enclosed claims.

Especially, other geometric configurations than the ones specifically shown in the figures may be useful to achieve the above described advantages, as long as such configurations comprises the above described necessary parts and the relations between them for achieving the present sealing purposes.