EP4587771A1 - Seal for a rotary kiln - Google Patents

Abstract

The invention relates to a device comprising a rotary kiln. The device has a housing (20) and a rotary tube (10), wherein the rotary tube (10) is rotatably connected to the housing (20), and a rotary tube seal (50) is arranged between the rotary tube (10) and the housing (20). The invention is characterized in that the rotary tube (10) has a first seal surface (30), and the housing (20) has a second seal surface (40), said first seal surface (30) and second seal surface (40) being arranged substantially perpendicularly to each other with respect to a longitudinal cross-section through the rotational axis of the rotary tube (10). The rotary tube seal (50) is arranged between the first seal surface (30) and the second seal surface (40), and the rotary tube seal (50) has a third seal surface (60) and a fourth seal surface (70), wherein the first seal surface (30) is arranged opposite the third seal surface (60), and the second seal surface (40) is arranged opposite the fourth seal surface (70).

Description

Seal for a rotary kiln

The invention relates to a seal for a rotary kiln.

Rotary kilns are used, for example, in the cement industry. The cement industry has high CCh emissions because, in addition to the CO2 from the fuel, CO2 from the starting material, such as lime, is also released during burning. Therefore, the current effort is to then separate the CO2 and not allow it to enter the environment. One technology for this, the so-called oxyfuel technology, relies on using oxygen that is as pure as possible for the process. The oxygen is converted into carbon dioxide, so that in the end the gas mixture would ideally consist of water and carbon dioxide. In practice, this cannot be achieved with this level of purity. However, every reduction of inert gas, for example nitrogen, ultimately reduces the effort required for separation. Therefore, any unwanted gas entry into the process is negative.

A point at which air can get into the device and thus into the process is, for example, the end of the rotary kiln (or both ends). Here the rotating rotary kiln comes into contact with the fixed apparatus. In addition, the rotary kiln can deform or bend to a certain extent, for example due to temperature and load, so for example a wobbling movement can occur at the end of the rotary kiln when rotating. This means, among other things, that the angle between the rotary tube and the housing is not constant. In addition, for example, a longitudinal and circumferential expansion can occur due to heating.

A seal for a rotary kiln is known from EP 274 090 A2.

From DE 10 2009 058 311 A1 an industrial furnace with a rotary kiln is known.

A seal for rotary kilns is known from DE 1 192 967 B.

From DE 31 14 695 A1 a device for sealing a gap is known. A barrier medium seal for rotary kilns is known from DE 43 03 298 C1.

In addition to the classic cement industry, the burning of gypsum, especially the gypsum resulting from the production of phosphoric acid, is currently an important topic, as it is no longer possible to simply dump or dump the resulting gypsum there. One of the sensible uses is therefore to burn the plaster into clinker. It is not CO2 that is produced as a gas, but rather SO3, which can then be fed back into the phosphoric acid process as sulfuric acid. Since this process produces large amounts of SO3 in the gas phase, a very good seal against the environment is also necessary to prevent an uncontrolled release of the SO3.

The sealing systems known from the prior art, for example, offer sufficient sealing in order to reduce thermal losses, for example. However, for subsequent CO2 separation, the gas tightness of the seal as well as its durability and reliability can be improved.

The object of the invention is to provide a seal which enables the rotary kiln to be sealed as well as possible, in particular against the penetration, in particular of air, into the kiln.

This task is solved by the device with the features specified in claim 1. Advantageous further developments result from the subclaims of the following description and the drawings.

The device according to the invention for the thermal treatment of a mineral material has a rotary kiln. It is preferably a rotary kiln for producing cement clinker. In particular, the device serves to operate the rotary kiln with oxygen that is as enriched as possible in order to then be able to separate the resulting carbon dioxide in a cost-effective manner so that it is not released into the atmosphere. This requires that the penetration of air from the environment and thus, for example, nitrogen (and argon) should be reduced as much as possible. In particular, the device is according to the Oxyfuel process operated. The device has a fixed housing and a rotatable rotating tube. The housing is rigid and represents the transition between the rotary kiln and the other equally rigid system components. The material and gas transfer between the housing and the rotary kiln is therefore essential, with the connection being such that the material and the gas between the housing and the rotary kiln is guided, but at the same time the rotary kiln has enough play to rotate and can also deform to a certain extent. For example, the housing includes the furnace head (or the furnace inlet). The device can preferably also have two housings, one at each end of the rotary tube. The rotary tube usually has a slight gradient of, for example, approx. 3 to 4%. In addition, it can happen that the rotary tube, which is usually very long, partially bends (for example due to the influence of heat), which can also lead to a wobbling movement of the rotary tube in the area of the housing. The rotary tube is rotatably connected to the housing in such a way that the flow of material is guaranteed. The connection is usually very open (with a large compensation area, i.e. a loose connection) to compensate for movements of the rotary tube. It is essential that the solid stream and largely the gas stream are passed through the connection. There does not have to be a direct, mechanical connection between the rotary tube and the housing and often does not exist. Therefore, a rotary tube seal is arranged between the rotary tube and the housing. The rotary tube seal conventionally means that as little of the cold ambient gases as possible can penetrate and thus cause cooling. The rotary kiln seal is not part of the rotary kiln or the housing, but is simply its own separate component. The rotary tube seal is arranged in a ring around the rotary kiln.

According to the invention, the rotary tube has a first sealing surface. The housing also has a second sealing surface. The first sealing surface and the second sealing surface are arranged essentially at right angles to one another with respect to a surface through the axis of rotation of the rotary tube. The perpendicularity can only be given in relation to the cross section, since one represents a flat surface and the other represents the surface of a cylinder jacket (or a surface parallel to the cylinder jacket). The rotary tube seal is between the first sealing surface and the second sealing surface arranged. The rotary tube seal has a third sealing surface and a fourth sealing surface. The third sealing surface and the fourth sealing surface are arranged at right angles to one another and are firmly connected to one another. The first sealing surface is arranged opposite the third sealing surface and the second sealing surface is arranged opposite the fourth sealing surface. The first sealing surface and the third sealing surface are ideally plane-parallel and the second sealing surface and the fourth sealing surface are ideally plane-parallel. Ideally, in the sense of the invention, means in the planned state, without, for example, any bending or thermal expansion of the rotary kiln. Such changes to the components will increasingly lead to deviations from this ideal case during ongoing operation. The ideal case therefore refers to the planned perfect optimal state. The first sealing surface, the second sealing surface, the third sealing surface and the fourth sealing surface have the geometric shape of a circular ring, a truncated cone shell or a cylinder shell. For example, two have the shape of a circular ring and two have the shape of a cylindrical shell, or all four have the shape of a truncated cone.

Essentially perpendicular in the sense of the invention means that the angle is 90° ± 7°, preferably 90° ± 5°, particularly preferably 90° ± 3°.

The essentially rectangular arrangement results in a high degree of flexibility. When the rotary tube moves, the two sealing surfaces arranged perpendicular to the axis of rotation of the rotary tube can move against each other transversely to the axis of rotation and the two sealing surfaces arranged coaxially to the axis of rotation of the rotary tube can also move against one another along the axis of rotation. A wobbling movement of the rotary tube can lead to a deviation from the coaxial arrangement. This means that by arranging two pairs of sealing surfaces arranged parallel to one another, the pairs being arranged essentially at right angles to one another, even a large wobbling movement of the rotary tube can be compensated for while maintaining the sealing effect. The adjacent sealing surfaces are then no longer exactly parallel to one another, but only essentially parallel to one another, which in the sense of the invention means that the deviation from parallelism is ± 7 °, preferably ± 5 °, particularly preferably ± 3 ° , lies. This not only makes it possible to reduce heat loss as usual minimize, but in particular to prevent as much as possible the penetration of nitrogen in particular at this point.

There are two preferred embodiments. On the one hand, the first sealing surface and the third sealing surface can be annular (cylindrical) and the second sealing surface and the fourth sealing surface can be disc-shaped. This means that the first sealing surface either on the surface of the rotary tube, but preferably at a distance from this surface coaxially surrounds the rotary tube and is itself coaxially surrounded by the third sealing surface. As a result, a displacement between the first sealing surface and the third sealing surface can take place along the sealing surfaces and thus, in a first approximation, parallel to the axis of rotation of the rotary tube. At the same time, the second sealing surface is arranged in a disk shape (and slightly tilted from the vertical arrangement due to the inclination of the rotary tube) on the housing. For this purpose, the fourth sealing surface is arranged plane-parallel, so that a movement perpendicular to the axis of rotation of the rotary tube can be compensated between the second sealing surface and the fourth sealing surface. The second alternative arrangement essentially represents a rotation of all sealing surfaces by 90°. Here, the first sealing surface and the third sealing surface are arranged in a disk shape. For example, the first sealing surface can be placed perpendicularly onto the surface of the rotary tube, in particular welded or screwed on. This results in a comparatively simple construction of the first sealing surface. The second sealing surface and the fourth sealing surface are annular. In particular, the second sealing surface is designed as a tube with a larger tube diameter than the rotary tube and is connected directly to the housing.

In a further embodiment of the invention, the rotary tube has a radial wobble, i.e. a movement around the axis, the stove pipe seal being designed to follow the radial wobble of the stove pipe, the radial wobble of the stove pipe being at least ± 100 mm, preferably at least ± 35 mm, more preferably at least ± 15 mm, particularly preferably at least ± 5 mm. If the rotary tube only has two bearings, a value of at least ± 100 mm is preferred; if the rotary tube has three bearings, a value of at least ± 35 mm is preferred. The deflection of the stove pipe from the perfect circular shape with the axis of rotation in the middle to the outside is seen as a wobble. The means in particular that the sealing surfaces arranged perpendicular to the axis of rotation of the rotary tube must be designed to shift relative to one another by this value. Likewise, the sealing surfaces, which are arranged essentially parallel to the axis of rotation of the rotary tube, must be able to compensate for a deviation in parallelism to one another resulting from this displacement. Typically, a wobble of ± 150 mm, preferably ± 100 mm, is not exceeded.

In a further embodiment, the rotary tube has a fifth sealing surface. The rotary tube seal has a sixth sealing surface. The first sealing surface and the fifth sealing surface are plane-parallel and the third sealing surface and the sixth sealing surface are plane-parallel. In purely practical terms, this means that instead of a larger, continuous first surface that is parallel to a larger third surface, two smaller two partial surfaces offset perpendicular to the surfaces can also be used. This increases the possibility of either adapting to the spatial conditions or creating a larger gas space, for example for a protective gas.

In a further embodiment of the invention, the rotary tube has an axial plan deviation of at least ± 1 mm, preferably of at least ± 10 mm, particularly preferably of at least ± 20 mm. This means that the length of the rotary tube does not change evenly, for example it lengthens when heated. For example, if there are adhesions inside the rotary tube that are only locally limited, the rotary tube can be colder at these points and therefore expand less. This means that the rotary tube does not have a flat, round cross-section at the end, but rather a corresponding displacement. This has a direct influence on the sealing surfaces, for example particularly strongly if the first sealing surface is arranged perpendicular to the axis of rotation of the rotary tube. In addition, other heat influences, for example heat from the oven and cold air from outside, can have an additional negative influence on the sealing surface and lead to increased deviation from the plan. In this example, the first sealing surface and the third sealing surface must be designed to compensate for this deviation from plan and still maintain the sealing effect. The plan deviation usually does not exceed a value of ± 35 mm. In a further embodiment of the invention, the rotary tube has a change in length between 0 mm and 500 mm, preferably 0 mm to 750 mm, between the cold state (ambient temperature) and the operating temperature (or to the current temperature during operation, which usually fluctuates around a target temperature) . Accordingly, the sealing surfaces arranged parallel to the axis of rotation of the rotary tube are designed to compensate for this offset when starting up and shutting down or during operation. In particular, at least one of the two sealing surfaces is designed to be correspondingly long (preferably the first sealing surface or the second sealing surface) so that a lateral displacement of the other sealing surface (preferably the third sealing surface or the fourth sealing surface) can take place.

In a further embodiment of the invention, the rotary tube seal has at least a first sealing element on the third sealing surface and at least a second sealing element on the fourth sealing surface. The rotary tube seal preferably has at least one third sealing element on the third sealing surface and at least one fourth sealing element on the fourth sealing surface. More preferably, the rotary tube seal has a first gas supply and a second gas supply. The first gas supply is designed to supply gas into the volume enclosed by the first sealing surface, the third sealing surface, the first sealing element and the third sealing element. The second gas supply is designed to supply gas into the volume enclosed by the second sealing surface, the fourth sealing surface, the second sealing element and the fourth sealing element. Particular preference is given to using CO2, cold process gas, for example from the gas stream behind the preheater, or the like. In the event of a leak, only CO2 or gas that is already present in the process gets into the rotary kiln. This does not make the later separation of CO2 more difficult. If CO2 escapes into the environment due to a leak, this can also be seen as non-critical, especially since it does not have the high temperature of the gas in the rotary kiln. In this way, the penetration of nitrogen into the open rotary tube can be largely avoided.

In a further embodiment of the invention, the rotary tube seal has at least one third sealing element on the third sealing surface. Between the fourth sealing surface and the housing a flexible surface element is arranged. This embodiment is preferred if the first sealing surface and the third sealing surface are annular and the second sealing surface and the fourth sealing surface are disc-shaped, i.e. the fourth sealing surface is arranged parallel to the rotary tube. In this case, only one movement along the rotary tube direction needs to be compensated between the second sealing surface and the fourth sealing surface. Therefore, the sealing between the second sealing surface and the fourth sealing surface can be carried out more easily. For example, a single second sealing element may be sufficient here. This can reduce complexity. In order to improve the seal in a simple manner, a flexible surface element is additionally arranged between the fourth sealing surface and the housing. A flexible surface element is something like a film, a fabric or the like, which has mobility and can therefore follow the movements of the fourth sealing surface and still creates a seal, i.e. prevents or at least significantly restricts an unhindered gas flow. At the same time, the fact that only one sealing element is arranged between the second sealing surface and the fourth sealing surface makes slight tilting easier without this affecting the sealing effect.

In a further embodiment of the invention, the rotary tube seal has a first gas supply and a second gas supply. The first gas supply is designed to supply gas into the volume enclosed by the first sealing surface, the third sealing surface, the first sealing element and the third sealing element. The second gas supply is designed to supply gas into the second sealing surface, the fourth sealing surface, the second sealing element, the housing and the flexible surface element. Particular preference is given to using CO2, cold process gas, for example from the gas stream behind the preheater, or the like. In the event of a leak, only CO2 or gas that is already present in the process gets into the rotary kiln. This does not make the subsequent separation of CO2 more difficult. If CO2 escapes into the environment due to a leak, this can also be seen as non-critical, especially since it does not have the high temperature of the gas in the rotary kiln. In this way, the penetration of nitrogen into the open rotary tube can be largely avoided. In a further embodiment of the invention, a flexible heat-resistant material is arranged between the fourth sealing surface and the second sealing element. The flexible heat-resistant material can, for example, and in particular be mineral wool. Mineral wool is readily available. It can also be a ceramic fabric or the like. It is essential that the flexible heat-resistant material has a certain flexibility in order to generate pressure to stabilize the second sealing element. In addition, the flexible heat-resistant material must be sufficiently temperature stable in order to be able to withstand the comparatively high temperatures that arise due to the immediate proximity to the rotary kiln.

In a further embodiment of the invention, the second sealing element is a sealing cord.

In a further embodiment of the invention, the device has force generating devices. The force generating devices are arranged above the sealing elements in such a way that the sealing elements are pressed against the opposite sealing surface by the force generating devices. This makes a particularly efficient gas-tight seal possible. Particularly preferably, each annular sealing element is in contact with a plurality of force generating devices. In order to additionally even out the force, a ring element can be arranged between the sealing element and the force generating device. The ring element, for example made of metal, ensures a flat distribution of the punctiform force generated by the force generating devices. The ring element can be made in one piece, but also in several parts, in particular from two to 75 ring element components. For example, a force generating device can have a spring. For example, a force generating device can be screwably connected to the sealing surface, whereby, for example, wear of the sealing element can be compensated for by screwing it in. At the same time, the wear can then be observed via the position of the force generating device - the further the force generating device is positioned inwards, the more the sealing element is worn. Furthermore, a control element can be arranged above the force generating devices, for example in Form of a rope or cable, which surrounds all force generating devices in a ring. The control element is designed to apply force to the force generating devices. For example, by shortening a rope-shaped control element, all force generating devices are subjected to equal force and so all sealing elements arranged underneath are pressed more strongly in the same way. In the same way, relaxing the control element can lead to a relief and thus to a lower pressure force on the sealing elements.

In a further embodiment of the invention, the third sealing surface and/or the fourth sealing surface has a first side element and a second side element. The side elements are arranged in such a way that the sealing elements can be replaced after the side elements have been removed. This simplifies maintenance. A removable side wall, for example, can be viewed as a side element. This is particularly preferred for the sealing surface that runs coaxially to the rotary tube. Here, the side element is moved along the axis of rotation to release the sealing element so that it can be replaced. The side element is then brought back into position and thus fixes the sealing element.

In a further embodiment of the invention, the third sealing surface and/or the fourth sealing surface has a spacer element. The spacer element can be designed, for example, as a ring, as a rope, as a pin, as a wear element or as balls. As a result, the force is guided through the spacer element, which can reduce wear on the sealing elements. In addition, centering can be achieved in relation to the spacer element and the sealing elements. The sealing element then only needs to be pressed with the force necessary for sealing.

Particularly preferably, the spacer element is at least partially rounded, in the simplest case it has a round cross section. This makes it possible to compensate for tilting of the rotary tube, so that parallelism between the first sealing surface and the third sealing surface or between the second sealing surface and the fourth sealing surface, which is no longer present due to a wobbling movement of the rotary tube, can be compensated for in a simple manner. In a further embodiment of the invention, the third sealing surface or fourth sealing surface, which is arranged essentially parallel to the rotary tube, has a curvature and is therefore not flat. This makes it possible to compensate for tilting of the rotary tube, so that parallelism between the first sealing surface and the third sealing surface or between the second sealing surface and the fourth sealing surface, which is no longer present due to a wobbling movement of the rotary tube, can be compensated for in a simple manner.

In a further embodiment of the invention, the device has a pressing device. The pressing device is in particular firmly connected to the housing or the foundation. The pressing device is connected via a force-generating pressing element to the third sealing surface or fourth sealing surface, which is perpendicular to the axis of rotation of the rotary tube. This allows the force required for sealing to be generated in a simple manner.

In a further alternative embodiment of the invention, the device has a pressing device. The pressing device is firmly connected to the rotating tube. The pressing device is connected via a force-generating pressing element to the third sealing surface or fourth sealing surface, which is essentially perpendicular to the axis of rotation of the rotary tube.

In a further embodiment of the invention, the device has a gas cooling device for cooling the third sealing surface and/or the fourth sealing surface. The first sealing surface and/or the second sealing surface is preferably also cooled. The temperature of the gases in the rotary tube typically exceeds 1000°C, so cooling can help improve sealing and reduce wear. In addition, the cooling and the associated reduced temperatures also enable the use of other, less heat-resistant materials for the sealing elements.

In a further embodiment of the invention, the rotary tube seal is gimballed on the housing. This suspends the rotary tube seal and its weight compensated by the counterweight, so that the weight of the rotary kiln seal is at least not completely transferred to the rotary tube and / or the housing via the third sealing surface and / or fourth sealing surface. This can significantly reduce wear.

In a further embodiment of the invention, the rotary tube seal is gimballed on the foundation. This also includes support via external components. As a result, the rotary tube seal is suspended or supported, so that the weight of the rotary kiln seal is at least not completely transferred to the rotary tube and/or the housing via the third sealing surface and/or fourth sealing surface. This can significantly reduce wear.

In a further embodiment of the invention, the rotary tube seal is connected to counterweights via a cable. As a result, the rotary tube seal is suspended and its weight is compensated for by the counterweight, so that the weight of the rotary kiln seal is at least not completely transferred to the rotary tube and/or the housing via the third sealing surface and/or fourth sealing surface. This can significantly reduce wear. Preferably, the rotating tube direction can be connected to two counterweights via two cable pulls, preferably one each on the side of the rotating tube.

In a further embodiment of the invention, a dust outlet is arranged between the housing and the second sealing surface at the lowest position. This makes it possible to easily remove the dust discharged from the rotary tube.

In a further embodiment of the invention, the rotary tube seal has a dust outlet. This is preferred if the rotary tube seal encloses a very low-lying area. This makes it possible to easily remove the dust discharged from the rotary tube.

In a further embodiment of the invention, the device has an internal gas supply. The internal gas supply is arranged in the area between the rotary tube, rotary tube seal and housing. The internal gas supply serves in particular to stir up dust again and remove it from the area. For this purpose, the internal gas supply can also only be operated in pulses, for example.

In a further embodiment of the invention, the first sealing surface and/or the second sealing surface has a wear plate. The wear plate serves to prevent wear of the first sealing surface and/or the second sealing surface due to the sealing elements. If necessary, the wear plate can be replaced without the load-bearing properties of the first sealing surface and/or the second sealing surface being impaired.

In a further embodiment of the invention, the first sealing surface and/or the second sealing surface are designed to be screwed or welded in segments.

In a further embodiment of the invention, a dust sealing element is arranged behind and adjacent to the second sealing surface and the fourth sealing surface. This is particularly preferred if a flexible surface element is arranged behind the dust sealing element. The main purpose of the dust sealing element is to minimize the escape of dust into the gap. The dust sealing element is preferably designed in a ring shape, preferably with an approximately round cross section. For example, the dust sealing element has a glass fiber fabric. For mechanical reinforcement, the dust sealing element can have a metal mesh, particularly on the surface. Inside, the dust sealing element can also be filled with metal wool, for example, and thus obtain a comparatively solid but at the same time adaptable external shape.

The device according to the invention is explained in more detail below using exemplary embodiments shown in the drawings.

Fig. 1 Simplified overall representation

Fig. 2 first example

Fig. 3 second example

Fig. 4 third example

Fig. 5 Detailed view Fig. 6 first example with wobbling movement

Fig. 7 fourth example

The representations are purely schematic and not to scale. For simplicity, only a small excerpt is shown.

A first, simplified overall representation is shown in FIG. The rotary tube 10 is arranged between two housings 20, which represent the inlet and outlet. In the example shown, the solids flow would flow from the top left to the bottom right, the gas flow from the bottom right to the top left. A combustion device for generating the necessary thermal energy is usually also arranged in the right housing 20. The rotary tube 10 itself is often mounted on two or more bearings and is driven on at least one of these bearings and thus rotated.

In the following, the usual inclination of the rotary tube, for example 4%, is omitted for simplicity. The same components are given the same reference numerals for simplification. The schematic representations preferably relate to both the inlet side of the rotary tube and the outlet side of the rotary tube.

Part of the cross section is shown perpendicular to the axis of rotation of the rotary tube 10, with only a small section of the lower part of the rotary tube 10 and a part of the housing 20 being shown. The rotary tube seal 50 shown would, in a first approximation, be arranged rotationally symmetrically about the axis of rotation of the rotary tube 10.

2 shows a first example in which the first sealing surface 30 runs parallel to the furnace pipe 10 and the second sealing surface 40 runs perpendicular to the axis of rotation of the rotary pipe 10. Between the rotary pipe 10 and the first sealing surface 30 there is a gap into which a fluid , preferably a gas, for example air or carbon dioxide, can be blown in in order to cool various components and thus also the first sealing surface. The second sealing surface 40 is arranged at a distance from the housing 20. On the one hand, this allows the inclination of the rotary tube 10 (not shown here) to be compensated for. On the other hand, this makes it possible to arrange a dust outlet 120 at the lowest point in this area, via which the dust outlet in particular The dust discharged from the rotary tube 10, which settles in this area, can be discharged. To enhance this effect, the device can have a protective device 130, for example a dust protection plate. The protective device 130 can be, for example, a dust protection plate or a heat protection plate on the outlet side of the rotary tube, or, for example, an overflow protection, heat protection or a dust protection on the inlet side of the rotary tube.

The rotary tube seal 50 is arranged between the first sealing surface 30 and the second sealing surface 40. The rotary tube seal 50 has a third sealing surface 60 which is arranged parallel to the first sealing surface 30 and a fourth sealing surface 70 which is arranged at right angles to the third sealing surface 60 and which in turn is arranged parallel to the second visible surface 40. If a wobbling movement of the rotary tube 10 now occurs, the third sealing surface 60 can move parallel to the first sealing surface 30, i.e. coaxially to the axis of rotation of the rotary tube 10, and at the same time the fourth sealing surface 70 can move perpendicular to the axis of rotation of the rotary tube parallel to the second sealing surface 40 . The sealing effect is therefore also ensured even if the rotary tube 10 is deformed and therefore has a wobbling movement. In the event of a wobbling movement, the rotary tube 10 can tilt in the area shown, so that the first sealing surface 30 and the third sealing surface 60 are then no longer exactly plane-parallel. However, this tilting can be compensated for via the round spacer element 100 and the sealing elements 80, so that the sealing effect is maintained.

In order to improve the sealing effect, the third sealing surface 60 and the fourth sealing surface 70 each have two circumferential sealing elements 80. In order to be able to easily replace the sealing elements 80, the third sealing surface 60 has removable side elements 91 and the fourth sealing surface 70 has removable side elements 92. The side elements 91 of the third sealing surface 60 are at a distance from the first sealing surface 30. Here, the spacer element 100 takes over the frictional connection function and enables good sealing between the first sealing surface 30 and the third sealing surface 60 via the round surface, even when the first sealing surface 30 is tilted. The side elements 92 of the fourth sealing surface 70 are longer and thus take over the adhesion function, so that a spacer element 100 can be dispensed with.

Since the annular rotary tube seal 50 preferably partially presses on the first sealing surface 30 with its weight (particularly on the top side, not shown), the third sealing surface 60 has a spacer element 100, for example a steel cable. As a result, the force does not rest primarily on the sealing elements 80, which means that they are not worn down unnecessarily and thus extend their service life. Therefore, the spacer element 100 can also serve for centering. The spacer element 100 is therefore arranged in the example shown and preferably centrally in the third sealing surface 60.

In order to optimize the tightness, the fourth sealing surface 40 is pressed against the second sealing surface 40 by means of a pressing device 110. The pressing device 110 can be, for example, a tension spring or a pneumatic cylinder. For example, three to thirty-two, preferably four to twenty-four pressing devices 110 can be present in order to generate the most uniform force possible.

Fig. 3 shows a second example, which differs from the first example in particular in that the first sealing surface 30 is placed as an annular disk on the rotary tube 10. Accordingly, the third sealing surface 60 is also arranged vertically. The second sealing surface 40 is designed as a cylinder jacket and has a larger diameter than the rotary tube 10. This also means in particular that the pressing device 110 in this case can be designed, for example, as a compression spring or as a pneumatic cylinder in order to press the third sealing surface 60 against the first sealing surface 30. In contrast to the first example, the dust outlet is arranged in the rotary tube seal 50, preferably close to the lowest point of the interior space that is being formed.

Fig. 4 shows a third example, which lies between the first example shown in Fig. 2 and the second example shown in Fig. 3. In the third example shown, all sealing surfaces 30, 40, 60, 70 are inclined by 45°. The first sealing surface 30 is perpendicular to the second sealing surface 40. The advantage of this embodiment is that the weight or the force generated by the pressing device 110 is transmitted evenly to the third sealing surface 60 and the fourth sealing surface 70. In addition, both the third sealing surface 60 and the fourth sealing surface 70 have a round spacer element 100. If a wobbling movement of the rotary tube 10 causes a tilt, the angle is distributed on both sides, so that the deviation from the plane-parallel arrangement is reduced.

5 shows an example of a first sealing surface 30 and a third sealing surface 60 in detail, as shown in the first example in FIG. 2. The fourth sealing surface 70 could also be constructed analogously in the second example shown in FIG. On the one hand, a ring element 82 is arranged behind the sealing element 80, for example a metal band. Force generating devices 84, for example springs, which can be screwed into the third sealing surface 60, press on the ring element 82. This punctual force is evened out via the ring element 82, so that the sealing element 80 is pressed evenly against the first sealing surface 30. And based on the position of the force generating device 84, which indicates how far the force generating device 84 is screwed into the third sealing surface, the wear of the sealing element 80 can be visually recognized from the outside. Alternatively, the force generating device 84 can have a measuring device to automatically record the position and thus the wear.

In addition, a gas supply 150 is shown, via which, for example, carbon dioxide or process gas can be introduced into the enclosed volume 140. In particular, this creates an excess pressure in the enclosed volume 140 relative to the surroundings and to the furnace pipe 10, so that this introduced gas escapes in the event of a leak. This reliably prevents penetration, particularly of nitrogen, as far as possible. At the same time, a leak, for example in the event of a defect in a sealing element, can be detected immediately based on the resulting gas flow through the gas supply 150.

Fig. 6 shows the first example with a rotary tube 10 tilted due to (thermal) deformation, which results in a wobbling movement. Because the end of the rotary tube 10 has now been moved downwards at the right end, on the one hand the entire Rotary tube seal 50 shifted downwards, which can be clearly seen from the fact that the fourth sealing surface 70 is no longer arranged centrally on the second sealing surface 40. On the other hand, the first sealing surface 30 and the third sealing surface 60 are no longer exactly parallel to one another. However, due to the round shape of the spacer element 100 and the pressed sealing element 80, the sealing effect remains.

A fourth example is shown in FIG. 7, which differs in some points from the second example shown in FIG. 3. The rotary tube seal 50 here has a very rough LI shape. While the third sealing surface 60 is designed as in the second example, the fourth sealing surface 70 only has one sealing element 80, the sealing element 80 being designed as a sealing cord. In order to prevent the sealing cord from sagging, especially on the underside, mineral wool 160 is arranged under the sealing cord. In addition, a flexible surface element 170 is arranged between the fourth sealing surface 70 and the housing 20. This makes it possible to tilt the fourth sealing surface 70 against the second sealing surface 40 and at the same time creates a gas space through the combination of the sealing cord and the flexible surface element 170, which can be filled with a sealing gas, for example. At the same time, a good seal can also be achieved between the first sealing surface 30 and the third sealing surface 60 due to the U-shape in a compact design by the pressing device 110.

Reference number 10 rotary tube 20 housing 30 first sealing surface 40 second sealing surface 50 rotary tube seal 60 third sealing surface

70 fourth sealing surface

80 sealing element 82 ring element 84 force generating device 91 side element 92 page element

100 spacer element

110 pressing device

120 Dust outlet 130 Guard

140 enclosed volume

150 gas supply

160 mineral wool

170 flexible surface element

Claims

Patent claims 1 . Device for the thermal treatment of a mineral material with a rotary kiln, the device having a fixed housing (20) and a rotatable rotary tube (10), the rotary tube (10) and the housing (20) being connected to one another for the direct mass transfer of the mineral material are, wherein the rotary tube (10) is rotatably connected to the housing (20), a rotary tube seal (50) being arranged between the rotary tube (10) and the housing (20), the rotary tube seal (50) not being part of the rotary tube kiln (10). or the housing (20), the rotary tube seal (50) being arranged in a ring shape around the rotary tube furnace (10), characterized in that the rotary tube (10) has a first sealing surface (30), the housing (20) having a second sealing surface (40), wherein the first sealing surface (30) and the second sealing surface (40) are arranged essentially at right angles to one another with respect to a surface through the axis of rotation of the rotary tube (10), the rotary tube seal (50) being between the first sealing surface (30 ) and the second sealing surface (40), the rotary tube seal (50) having a third sealing surface (60) and a fourth sealing surface (70), the third sealing surface (60) and the fourth sealing surface (70) being arranged at right angles to one another and are firmly connected to one another, the first sealing surface (30) being arranged opposite the third sealing surface (60) and the second sealing surface (40) being arranged opposite the fourth sealing surface (70), the first sealing surface (30) and the third sealing surface (60) are ideally plane-parallel, with the second sealing surface (40) and the fourth sealing surface (70) ideally being plane-parallel, with the first sealing surface (30), the second sealing surface (40), the third sealing surface (60) and the fourth sealing surface ( 70) have the geometric shape of a circular ring, a truncated cone shell or a cylindrical shell. 2. Device according to claim 1, characterized in that the first sealing surface (30) and the third sealing surface (60) are annular and the second sealing surface (40) and the fourth sealing surface (70) are disc-shaped or the first sealing surface (30) and the third sealing surface (60) is disk-shaped and the second sealing surface (40) and the fourth sealing surface (70) are annular. 3. Device according to one of the preceding claims, characterized in that the rotary tube (10) has a fifth sealing surface, the rotary tube seal (50) having a sixth sealing surface, the first sealing surface (30) and the fifth sealing surface being plane-parallel, the The third sealing surface (60) and the sixth sealing surface are plane-parallel. 4. Device according to one of the preceding claims, characterized in that the rotary tube seal (50) has at least a first sealing element (80) on the third sealing surface (60), the rotary tube seal (50) having at least one second sealing element (80) on the fourth Has sealing surface (70). 5. Device according to claim 4, characterized in that the rotary tube seal (50) has at least one third sealing element (80) on the third sealing surface (60), the rotary tube seal (50) having at least one fourth sealing element (80) on the fourth sealing surface ( 70). 6. Device according to claim 5, characterized in that the rotary tube seal (50) has a first gas supply (150) and a second gas supply (150), the first gas supply (150) for supplying gas into the gas supply from the first sealing surface (30 ), the third sealing surface (60), the first sealing element (80) and the third sealing element (80) enclosed volume (140) is formed, the second gas supply (150) for supplying gas into the volume (140) surrounded by the second sealing surface (40). , the fourth sealing surface (70), the second sealing element (80) and the fourth sealing element (80) enclosed volume (140) is formed. 7. The device according to claim 4, characterized in that the rotary tube seal (50) has at least one third sealing element (80) on the third sealing surface (60), with a flexible surface element (20) between the fourth sealing surface (70) and the housing (20). 170) is arranged. 8. The device according to claim 7, characterized in that the rotary tube seal (50) has a first gas supply (150) and a second gas supply (150), the first gas supply (150) for supplying gas into the gas supply from the first sealing surface (30 ), the third sealing surface (60), the first sealing element (80) and the third sealing element (80) enclosed volume (140) is formed, the second gas supply (150) for supplying gas into the volume (140) surrounded by the second sealing surface (40). , the fourth sealing surface (70), the second sealing element (80), the housing (20) and the flexible surface element (170) is formed. 9. Device according to one of claims 7 to 8, characterized in that a flexible heat-resistant material, in particular mineral wool, is arranged between the fourth sealing surface (40) and the second sealing element (80). 10. Device according to one of claims 7 to 9, characterized in that the second sealing element (80) is a sealing cord. 11. Device according to one of claims 4 to 10, characterized in that the sealing elements (80) are pressed with a force generating device (84). 12. The device according to claim 11, characterized in that a ring element (82) is arranged between the sealing element (80) and the force generating device (84). 13. Device according to one of claims 4 to 11, characterized in that the third sealing surface (60) and / or the fourth sealing surface (70) has a first side element (91, 92) and a second side element (91, 92), wherein the side elements (91, 92) are arranged such that the sealing elements (80) can be replaced after the side elements (91, 92) have been removed. 14. Device according to one of the preceding claims, characterized in that the third sealing surface (60) and / or the fourth sealing surface (70) has a spacer element (100). 15. Device according to one of the preceding claims, characterized in that the device has a pressing device (110), the pressing device (110) being firmly connected to the housing (20) or the foundation, the pressing device (110) having a force-generating Pressing element is connected to the third sealing surface (60) or fourth sealing surface (70) which is essentially perpendicular to the axis of rotation of the rotary tube (10). 16. Device according to one of the preceding claims, characterized in that the device has a gas cooling device for cooling the third sealing surface (60) and / or the fourth sealing surface (70). 17. The device according to claim 16, characterized in that the device has a gas cooling device for cooling the first sealing surface (30) and / or the second sealing surface (40). 18. Device according to one of the preceding claims, characterized in that the rotary tube seal (50) is gimballed on the housing (20) or foundation. 19. Device according to one of the preceding claims, characterized in that a dust outlet (120) is arranged between the housing (20) and the second sealing surface (40) at the lowest position. 20. Device according to one of the preceding claims, characterized in that the rotary tube seal has a dust outlet. 21 .Device according to one of the preceding claims, characterized in that the device has an internal gas supply, the internal gas supply being arranged in the area between the rotary tube (10), the rotary tube seal (50) and the housing (20). 22. Device according to one of the preceding claims, characterized in that a control element is arranged above the force generating devices (84), which annularly controls all force generating devices (84). encloses, wherein the control element is designed to apply force to the force generating devices (84). Device according to one of the preceding claims, characterized in that the first sealing surface (30) and/or the second sealing surface (40) has a wear plate. Device according to one of the preceding claims, characterized in that the first sealing surface (30) and/or the second sealing surface (40) are designed to be screwed or welded in segments. Device according to one of the preceding claims, characterized in that a dust sealing element is arranged behind and adjacent to the second sealing surface (40) and the fourth sealing surface (70). Device according to claim 25, characterized in that the dust sealing element has a glass fiber fabric. Device according to one of claims 25 to 26, characterized in that the dust sealing element has a metal mesh.