Door sealing device for industrial furnace

The present invention relates to a door sealing device for an industrial furnace. More specifically, the invention relates to vertical sealing devices intended for use in conjunction with vertically arranged doors to an industrial furnace.

Today, industrial furnaces are used for heating of various materials, such as metals. In order to avoid unnecessary thermal losses during operation, openable doors are used with the industrial furnaces, which can be sealed when no material at the moment needs transportation into or out of the furnace. Generally, such doors are arranged vertically, and are consequently opened or closed using a vertical door movement. Advantageously, the door is opened by raising it and closed by again lowering it.

A problem associated with the operation of this type of doors is that it is difficult to obtain a satisfying seal between the moving side wall of the door and the wall of the industrial furnace. Such a seal is desirable in order to avoid thermal losses, leakage of outside air into the furnace and leakage of flue gases, etc. Because of the elevated temperatures inside the industrial furnace, it is difficult to find sealing materials with sufficient life times in the inhospitable environment surrounding the edge of the door.

The present invention solves the above problem.

Thus, the present invention relates to a door sealing device for an industrial furnace which is vertical and opened vertically, and is characterized in that each one of the side edges of the door is arranged to run inside and along a re-

spective tube that has a longitudinal slit and extends vertically, in that each tube is fixed in relation to the furnace, in that the tubes are designed to spring back towards a respective position in which the slit is closed, and arranged to enclose the side edge of the door along essentially the whole length of the side edge when the door is in its closed position, and in that a liquid coolant is arranged to stream through the tubes and essentially fill up the whole space defined by the combination of the inner surfaces of each tube and the outer surfaces of the respective side parts of the door .

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

Figure 1 is a simplified front view of a preferred door sealing device according to the present invention.

Figure 2 is a simplified top view of the preferred door sealing device according to Figure 1.

Figure 3a is a detail view of a first preferred edge sealing device in cross-section as seen from the top according to the present invention.

Figure 3b is a detail view of a second preferred edge sealing device from the side according to the present invention.

Figure 3c is a detail view of a third preferred edge sealing device from the side according to the present invention.

Figure 3d is a detail view of a fourth preferred edge sealing device from the side according to the present invention.

With common reference numerals, in Figure 1 and in Figure 2 are shown an industrial furnace 1, which in one of its side walls is equipped with a through opening 2 for bringing material into or out of the furnace 1. A vertically arranged and openable door 3 is arranged to tightly cover the through opening 2. The door 3 is opened by bringing it upwards, and is reclosed by lowering it back to its original position. In the drawings, the door 3 is shown in a partly open position.

Both vertical side edges 4a, 4b of the door 3 each run inside a respective vertically arranged tube 5a, 5b, extending essentially along the whole length of its respective side edge 4a, 4b when the door 3 is in its closed position. Each of the respective tubes 5a, 5b is furnished with a longitudinal slit 6a, 6b, through which slit the respective side edge 4a, 4b is inserted. Thus, both side edges 4a, 4b of the door 3 are arranged to completely be surrounded by their respective tubes 5a, 5b when the door 3 is in its closed position. When the door 3 is opened or closed, its side edges 4a, 4b run inside the tubes 5a, 5b in the longitudinal, essentially vertical, direction of the tubes 5a, 5b.

A circulation device 7 for liquid coolant is arranged to continuously let coolant flow through the tubes 5a, 5b. In order to achieve this, the circulation device 7 supplies coolant, via supply conduits 7a, at the upper opening 8a, 8b of each respective tube 5a, 5b, and collects the coolant in a trough 9 which is arranged straight below the lower openings 10a, 10b of both respective tubes 5a, 5b, through which the

coolant flows, and the circulation device 7 is arranged to transport the coolant, via a return conduit 7b, back to the supply site by the help of a pumping device (not shown) .

Preferably, the coolant is water, but it can be constituted of any suitable, liquid coolant.

The tubes 5a, 5b are manufactured from an elastic material, such as for example rubber. Since the coolant continuously flows through the tubes 5a, 5b, the tubes 5a, 5b are effectively cooled during operation, and it is therefore possible to achieve a satisfactory life time for the tubes 5a, 5b. Furthermore, both the respective tubes 5a, 5b are arranged to spring back, by the help of the elastic nature of the mate- rial of manufacture, towards a position in which the slit 6a, 6b is closed. This leads to the tube 5a, 5b, through the spring action, tightly closing against both the interior side 11a and the external side lib of the door 3. See Fig. 2. Thus, leakage of coolant through the slit 6a, 6b is mini- mized.

The tubes 5a, 5b are tight-fittingly fastened to the external wall of the industrial furnace 1 by the aid of sealing fastening means 13a, 13b. Furthermore, an overpressure arises inside the tubes 5a, 5b because of the liquid column of coolant inside the tubes 5a, 5b, which leads to the volume defined by the interior surfaces of the tubes 5a, 5b in combination with the exterior surfaces of the side portions of the door 3 always being completely filled with coolant during operation. By the side portions of the door 3 is meant the side edges 4a, 4b of the door 3 as well as the small portion of the inner 11a and outer lib surfaces of the door 3 being inserted inside the respective tube 5a, 5b. In this way, an

efficient sealing of the side edges 4a, 4b of the door 3 is achieved. Also, the door 3 is sealed in a conventional manner along its lower and its upper edges, respectively, by the use of sealing devices that are not, for reasons of simplicity, shown in the drawings. All in all, a satisfactory seal of the door 3 is thus achieved, so that atmospheric air cannot leak into the industrial furnace 1, and so that furnace atmosphere gases cannot leak out of the industrial furnace 1 through any of the edges of the door 3.

Since the tubes 5a, 5b are arranged to spring back against a position in which their respective slits 6a, 6b are closed, this sealing effect is achieved both in those places where the side edges 4a, 4b of the door 3 run through the slits 6a, 6b, and where the side edges 4a, 4b of the door 3 do not run through the slits 6a, 6b because of the door 3 having been partly opened.

However, a certain leakage of coolant through the slits 6a, 6b can be acceptable, and is in this case caught by the trough 9 for return to the circulation device 7. Such leakage will especially be present partly further down along the tubes 5a, 5b, because of the increasing pressure in the tubes 5a, 5b due to increasing liquid depth partly in the area where the slit 6a, 6b is being closed or being opened around the lower edge 12 of the door 3 when the door 3 is opened or closed. However, in certain cases it may be desirable to minimize such leakage of coolant.

A preferred way to achieve such a minimization of leakage through the slits 6a, 6b is to design the tubes 5a, 5b so that the spring action, leading to each tube 5a, 5b springing back towards a position where its slit 6a, 6b is closed,

increases downwards in the longitudinal direction of the tube 5a, 5b. By way of example, this can be achieved by making the tube 5a, 5b stiffer and/or thicker further down as compared to further up, or by arranging additional, circular springs (not shown) , contributing to further increase of the return springing action of the tube 5a, 5b further down on the same.

Furthermore, it is preferred to minimize the leakage through the slits 6a, 6b by the provision to the door sealing device of a special edge sealing device, specifically minimizing the leakage which would otherwise risk to arise through the particular area in which the slit 6a, 6b is closing or opening around the lower edge 12 of the door 3 when the door 3 is opened or closed. Preferred examples of such edge sealing devices are illustrated in Figures 3a to 3d. Figures 3a to 3d only show detail views of one of the above-described edges 4a, 4b, even though both of the edges 4a, 4b are preferably but not necessarily furnished with identical edge sealing devices. Moreover, reference numerals are still common be- tween the different figures.

Thus, Figure 3a shows a first preferred edge sealing device 20 according to the present invention. The side edge 4a of the door 3 is provided with a piece of sheet metal 21 mounted on the outside of the side edge 4a, and tight-fittingly attached along with the complete vertical elongation of the edge 4a, and extending outwards some distance in the plane of the door 3, and further bending around the side of the industrial furnace 1, and thereafter running a certain distance along this side. In this preferred embodiment, the tube 5a is arranged along a side of the industrial furnace 1 which is adjacent to the side through which the through opening 2 is arranged. Furthermore, it is the external side portion 22 of

the sheet metal 21 which is inserted through the slit 6a, 6b, and which is consequently arranged to be displaced inside and along the tube 5a when the door 3 is opened or closed.

The sheet metal 21 is essentially thinner than the door 3. In order to avoid thermal damage to the sheet metal 21, it is arranged to be cooled separately from the door 3. For example, this can be arranged by the help of cooling flanges 23 mounted on the side of the sheet metal 21 facing outwards. Furthermore, the circulation device 7 can be arranged to let part of the supplied coolant flow over the side of the sheet metal 21 facing outwards, so that a thin film of coolant continuously is reformed on the surface of the sheet metal 21 from above, and thus cools the sheet metal 21.

Because of the small thickness of the sheet metal 21, the leakage of coolant through the slit 6a is minimized at the location where the slit 6a is closing or opening around the lower edge of the sheet metal 21 when the door 3 is being opened or closed.

Finally, in this preferred embodiment the trough 9 is arranged to be sufficiently large in order to capture leaking coolant, even in case the tube 5a is arranged on a side of the industrial furnace which is not the same side as the one where the through opening 2 is arranged.

Figure 3b is a detail view from the side illustrating a second preferred edge sealing device 30. Thus, Figure 3b shows the tube 5a with its accompanying slit 6a from the side at the very location where the slit 6a at the moment is closing around the lower edge 12 of the door 3. As is clearly seen in figure 3b, the lower edge 12 of the door 3 in this preferred

embodiment is designed with a form that tapers off in the longitudinal direction of the side edge 4a of the door 3, where the tapered form essentially follows the form naturally assumed by the slit 6a at the closing location when the tube 5a closes around the termination of the lower edge 12 of the door 3 against the side edge 4a of the door 3. This naturally arisen form of the slit 6a arises as a consequence of the elastic nature of the material of the tube 5a.

Thus, when the door 3 moves upwards or downwards along the slit 6a, by opening or closing the door 3, the slit 6a will always assume essentially the same form as will the termination of the lower edge 12 of the door 3 against the side edge 4a of the door 3, and consequently the slit 6a will connect essentially tight-fittingly against the termination of the lower edge 12 of the door 3 against the side edge 4a of the door 3. This leads to better sealing between the door and the tube 5a, together with the associated advantages with minimized leakage of coolant through the slit 6a.

Figure 3c shows a third preferred edge sealing device 40, shown from the same perspective as that in Figure 3b. As is illustrated in Figure 3c, the lower edge 12 of the door 3 comprises a sealing device 41, fixed to the door 3 and run- ning inside the tube 5a and arranged to tight-fittingly bear against the interior surface of the tube 5a from the inside, and thereby to seal the area of connection between the tube 5a and the termination of the lower edge 12 of the door 3 against the side edge 4a of the door 3.

Thereby, the same advantages as described in connection with the second preferred edge sealing device 30 are achieved.

Figure 3d shows a fourth preferred edge sealing device 50, like Figure 3c shown from the same perspective as that of Figure 3b. As is illustrated in Figure 3c, the slit 6a of the tube 5a and the lower edge 12 of the door 3 comprise cooper- ating zip type locking means 51, 52, arranged to close the slit 6a of the tube 5a after the lower edge 12 of the door 3 when the door 3 is being opened, and reversely to open the slit 6a of the tube 5a in front of the lower edge 12 of the door 3 when the door 3 is being closed. Those sections of the zip lock which are closed are arranged to be essentially impenetrable to the coolant, leading to the same advantages in terms of good sealing as described in connection with the second preferred edge sealing device 30.

The cooperating locking means 51, 52 are preferably of the type with good sealing effect used in dry suits, even if the dimension of the locking means 51, 52 naturally can be greatly varied depending on the size of the door 3 and of the tube 4a.

It should be realized that the preferred edge sealing devices 20, 30, 40, 50 can be used individually or together in various combinations. Also, it is not in all applications necessary to additionally seal the edge of the door 3 at all. Furthermore, it is possible to use the present invention together with other, conventional or today unknown edge sealing devices without departing from the basic idea of the invention .

Above, the present invention has been explained with reference to exemplifying embodiments. However, it should be realized that the invention should not be considered limited by

these embodiments, but the invention can be varied within the scope of the attached claims.