Seal for a rotary kiln

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

[0001] Seal for a rotary kiln

[0002] The invention relates to a seal for a rotary kiln.

[0003] Rotary kilns are used, for example, in the cement industry. The cement industry has high CO2 emissions because, in addition to the CO2 from the fuel, CO2 is also released from the reactant, such as lime, during combustion. Therefore, the current aim is to subsequently separate the CO2 and prevent it from escaping into the environment. One technique for this, known as oxyfuel technology, relies on the use of the purest possible oxygen for the process. The oxygen is converted to carbon dioxide, so that the ideal final gas mixture would consist of water and carbon dioxide. In practice, this is not possible at this purity. However, any reduction in inert gas, such as nitrogen, ultimately reduces the separation effort. Therefore, any unwanted gas input into the process is negative.

[0004] One point where air can enter the device and thus the process is, for example, the end of the rotary kiln (or both ends). This is where the rotating rotary kiln touches the fixed equipment. In addition, the rotary kiln can deform or bend to a certain extent, for example due to temperature and load, which can lead to a wobbling motion at the end of the rotary kiln during rotation. This means, among other things, that the angle between the rotary kiln and the housing is not constant. In addition, longitudinal and circumferential expansion can occur due to heating, for example.

[0005] A seal for a rotary kiln is known from EP 274 090 A2.

[0006] An industrial furnace with a rotary kiln is known from DE 10 2009 058 311 A1.

[0007] A seal for rotary kilns is known from DE 1 192 967 B.

[0008] DE 31 14 695 A1 discloses a device for sealing a gap. DE 43 03 298 C1 discloses a barrier medium seal for rotary kilns.

[0009] In addition to the traditional cement industry, the burning of gypsum, particularly the gypsum produced during phosphoric acid production, is currently an important topic, as simple landfilling or dumping of the resulting gypsum should no longer be possible. Therefore, one of the sensible uses is burning the gypsum to produce clinker. This process produces not CO2, but SO3 as a gas, which can then be recycled to the phosphoric acid process as sulfuric acid. Since this process produces large quantities of SO3 in the gas phase, very good sealing against the environment is also necessary to prevent the uncontrolled release of SO3.

[0010] State-of-the-art sealing systems, for example, provide sufficient sealing to reduce thermal losses. However, for subsequent CO2 capture, the gas-tightness of the seal, as well as its durability and reliability, can be improved.

[0011] 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.

[0012] This object is achieved by the device having the features specified in claim 1. Advantageous further developments emerge from the subclaims of the following description and the drawings.

[0013] The device according to the invention for the thermal treatment of a mineral material comprises a rotary kiln. This is preferably a rotary kiln for the production of cement clinker. In particular, the device serves to operate the rotary kiln with oxygen that is as enriched as possible in order to subsequently 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 ambient air and thus, for example, of nitrogen (and argon) is reduced as much as possible. In particular, the device is operated according to the oxyfuel process. The device has a stationary housing and a rotatable rotary kiln. The housing is rigid and represents the transition between the rotary kiln and the other, likewise rigid, plant components.The material and gas transfer between the housing and the rotary kiln is therefore crucial. The connection is such that the material and gas are guided between the housing and the rotary kiln, but the rotary kiln also has enough play to rotate and can also deform to a certain extent. For example, the housing encloses the kiln head (or kiln inlet). The device can preferably also have two housings, one at each end of the rotary kiln. The rotary kiln typically has a slight gradient of, for example, approximately 3 to 4%. In addition, the usually very long rotary kiln may partially bend (for example due to heat), which can also lead to a wobbling movement of the rotary kiln in the area of ​​the housing. The rotary kiln is rotatably connected to the housing in such a way that the material flow is ensured.The connection is usually very open (with a large compensation area, i.e. a loose connection) to compensate for movements of the rotary kiln. It is important that the solids flow and most of the gas flow are guided through the connection. A direct, mechanical connection between the rotary kiln and the housing is not necessary and often is not there anyway. Therefore, a rotary kiln seal is arranged between the rotary kiln and the housing. The rotary kiln seal conventionally ensures that as few 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 a separate component in its own right. The rotary kiln seal is arranged in a ring around the rotary kiln.

[0014] 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 substantially at right angles to one another with respect to a surface through the axis of rotation of the rotary tube. The right angle can only be given with respect to the cross-section, since one represents a flat surface and the other the surface of a cylinder jacket (or a surface parallel to the cylinder jacket). The rotary tube seal is arranged between the first sealing surface and the second sealing surface. 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 firmly connected to one another. The first sealing surface is opposite the third sealing surface and the second sealing surface is 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. In the sense of the invention, the ideal case means in the planned state, without, for example, bending or thermal expansion of the rotary kiln. Such changes to the components will increasingly lead to deviations from this ideal case during 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, or a cylindrical surface. For example, two have the shape of a circular ring and two have the shape of a cylindrical surface, or all four have the shape of a truncated cone.

[0015] In the sense of the invention, substantially perpendicular means that the angle is 90° ± 7°, preferably 90° ± 5°, particularly preferably 90° ± 3°.

[0016] The essentially rectangular arrangement results in a high degree of flexibility. When the rotary tube moves, the two sealing surfaces arranged perpendicular to the rotary tube's axis of rotation can shift against each other transversely to the axis of rotation, and the two sealing surfaces arranged coaxially to the rotary tube's axis of rotation can shift against each other longitudinally to the axis of rotation. A wobbling movement of the rotary tube can lead to a deviation from the coaxial arrangement. Thus, by arranging two pairs of sealing surfaces arranged parallel to each other, with the pairs arranged essentially at right angles to each other, 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 each other, but only essentially parallel to each other, which, in the context of the invention, means that the deviation from parallelism is ± 7°, preferably ± 5°, particularly preferably ± 3°. This not only makes it possible to minimize heat loss as is conventional, but also largely prevents the penetration of nitrogen at this point.

[0017] This results in 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 is 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. This allows a displacement between the first sealing surface and the third sealing surface to occur along the sealing surfaces and thus, to a first approximation, parallel to the axis of rotation of the rotary tube. At the same time, the second sealing surface is disc-shaped (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 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 disc shape. For example, the first sealing surface can be placed perpendicularly on the surface of the rotary tube, in particular welded or screwed on. This results in a comparatively simple design for 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 diameter than the rotary tube and is connected directly to the housing.

[0018] In a further embodiment of the invention, the rotary tube has a radial wobble, i.e. a movement around the axis, wherein the furnace tube seal is designed to follow the radial wobble of the furnace tube, wherein the radial wobble of the furnace tube is 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 has only 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. Wobble is considered to be the deflection of the furnace tube from the perfect circular shape with the axis of rotation in the center towards the outside. This means in particular that the sealing surfaces arranged perpendicular to the axis of rotation of the rotary tube must be designed to be shifted relative to one another by this value.Likewise, the sealing surfaces, which are arranged essentially parallel to the rotary tube's axis of rotation, must be able to compensate for any deviation in parallelism resulting from this displacement. Typically, a wobble of ± 150 mm, preferably ± 100 mm, is not exceeded.

[0019] 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 practical terms, this means that instead of a larger, continuous first surface parallel to a larger third surface, two smaller partial surfaces offset perpendicular to the surfaces can 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.

[0020] In a further embodiment of the invention, the rotary tube has an axial flatness 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. If, for example, adhesions occur inside the rotary tube which are only locally limited, the rotary tube can be colder at these points and therefore expand less. As a result, the rotary tube does not have a flat, round cross-section at the end, but rather a corresponding displacement occurs. 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 furnace and cold air from outside, can have an additional negative impact on the sealing surface and lead to an increased flatness deviation. In this example, the first sealing surface and the third sealing surface must be designed to compensate for this flatness deviation and still maintain the sealing effect. Typically, the flatness deviation does not exceed a value of ± 35 mm. In a further embodiment of the invention, the rotary tube has a change in length of 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 during startup and shutdown 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.

[0021] 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 a third sealing element on the third sealing surface and at least a 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.Particularly preferred is CO2, cold process gas, for example, from the gas stream downstream of the preheater, or similar. In the event of a leak, only CO2 or gas already present in the process enters the rotary kiln. This does not impede the subsequent separation of CO2. If CO2 escapes into the environment due to a leak, this can also be considered uncritical, especially since it does not have the same high temperature as the gas in the rotary kiln. This largely prevents the penetration of nitrogen into the rotary kiln.

[0022] In a further embodiment of the invention, the rotary tube seal has at least a third sealing element on the third sealing surface. A flexible surface element is arranged between the fourth sealing surface and the housing. 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 disk-shaped, i.e. the fourth sealing surface is arranged parallel to the rotary tube. In this case, only a movement along the rotary tube direction needs to be compensated between the second sealing surface and the fourth sealing surface. The seal between the second sealing surface and the fourth sealing surface can therefore be implemented more simply. For example, a single second sealing element may be sufficient here. This can reduce complexity.To further improve the seal in a simple way, a flexible surface element is additionally arranged between the fourth sealing surface and the housing. A flexible surface element can be something like a film, a fabric, or the like, which is flexible and can thus follow the movements of the fourth sealing surface while still creating a seal, i.e., preventing or at least significantly restricting unimpeded 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 it easier to tilt slightly without impairing the sealing effect.

[0023] In a further embodiment of the invention, the rotary kiln 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, the housing, and the flexible surface element. Particular preference is given to using CO2, cold process gas, for example from the gas stream downstream of the preheater, or the like. In the event of a leak, only CO2 or gas already present in the process enters the rotary kiln. This means that the subsequent separation of CO2 is not made more difficult.If CO2 escapes into the environment due to a leak, this can also be considered uncritical, especially since it does not have the high temperature of the gas in the rotary kiln. This can largely prevent the penetration of nitrogen into the rotary kiln. 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 degree of flexibility in order to generate pressure to stabilize the second sealing element.In addition, the flexible heat-resistant material must be sufficiently temperature-stable to withstand the comparatively high temperatures caused by the immediate proximity to the rotary kiln.

[0024] In a further embodiment of the invention, the second sealing element is a sealing cord.

[0025] In a further embodiment of the invention, the device comprises 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 enables a particularly efficient, gas-tight seal. Particularly preferably, each annular sealing element is in contact with a plurality of force-generating devices. To further even out the force application, a ring element can be arranged between the sealing element and the force-generating device. The ring element, made of metal, for example, ensures a flat distribution of the point-like force generated by the force-generating devices. The ring element can be constructed in one piece or in multiple pieces, in particular from two to 75 ring element components. For example, a force-generating device can comprise a spring.For example, a force generating device can be screwed to the sealing surface, whereby wear on the sealing element can be compensated for, for example, by screwing it in. At the same time, wear can then be monitored via the position of the force generating device - the further the force generating device is positioned inwards, the more worn the sealing element is. Furthermore, a control element can be arranged above the force generating devices, for example in the form of a rope or cable that encloses all the 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 the force generating devices are subjected to the same force, thus pressing all the sealing elements arranged below them with the same force.In the same way, a relaxation of the control element can lead to a relief and thus to a lower pressure force on the sealing elements.

[0026] 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 such that the sealing elements can be replaced after removal of the side elements. This simplifies maintenance. A removable side wall, for example, can be considered as a side element. This is particularly preferred for the sealing surface running coaxially to the rotary tube. 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 moved back into position, thus fixing the sealing element.

[0027] 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, a cable, a pin, a wear element, or balls. This guides the force through the spacer element, which can reduce wear on the sealing elements. In addition, this can achieve centering with respect to the spacer element and the sealing elements. This means that the sealing element only needs to be pressed with the force required for sealing.

[0028] Particularly preferably, the spacer element is at least partially rounded; in the simplest case, it has a round cross-section. This enables compensation in the event of tilting of the rotary tube, so that a loss of parallelism between the first sealing surface and the third sealing surface or between the second sealing surface and the fourth sealing surface due to a wobbling movement of the rotary tube can be easily compensated. 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 enables compensation in the event of tilting of the rotary tube, so that a loss of parallelism between the first sealing surface and the third sealing surface or between the second sealing surface and the fourth sealing surface due to a wobbling movement of the rotary tube can be easily compensated.

[0029] In a further embodiment of the invention, the device comprises a pressure device. The pressure device is, in particular, firmly connected to the housing or the foundation. The pressure device is connected via a force-generating pressure element to the third sealing surface or fourth sealing surface, which is perpendicular to the rotational axis of the rotary tube. This allows the force required for sealing to be generated in a simple manner.

[0030] In a further alternative embodiment of the invention, the device comprises a pressing device. The pressing device is fixedly connected to the rotary tube. The pressing device is connected via a force-generating pressing element to the third sealing surface or fourth sealing surface, which is substantially perpendicular to the rotational axis of the rotary tube.

[0031] In a further embodiment of the invention, the device comprises a gas cooling device for cooling the third sealing surface and / or the fourth sealing surface. Preferably, the first sealing surface and / or the second sealing surface are also cooled. The temperature of the gases in the rotary kiln typically exceeds 1000°C, so cooling can help improve the seal 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.

[0032] In a further embodiment of the invention, the rotary kiln seal is gimbal-mounted on the housing. This suspends the rotary kiln seal, and its weight is compensated by the counterweight, so that the weight of the rotary kiln seal is at least not completely transferred to the rotary kiln and / or the housing via the third sealing surface and / or fourth sealing surface. This can significantly reduce wear.

[0033] In a further embodiment of the invention, the rotary kiln seal is gimbal-mounted to the foundation. This also includes support via external components. This suspends or supports the rotary kiln seal, so that the weight of the rotary kiln seal is at least not completely transferred to the rotary kiln and / or the housing via the third sealing surface and / or fourth sealing surface. This can significantly reduce wear.

[0034] In a further embodiment of the invention, the rotary kiln seal is connected to counterweights via a cable pull. This suspends the rotary kiln seal, and its weight is compensated by the counterweight, so that the weight of the rotary kiln seal is at least not completely transferred to the rotary kiln and / or the housing via the third sealing surface and / or fourth sealing surface. This can significantly reduce wear. Preferably, the rotary kiln seal can be connected to two counterweights via two cable pulls, preferably one on each side of the rotary kiln.

[0035] 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 easy to remove the dust discharged from the rotary tube.

[0036] In a further embodiment of the invention, the rotary tube seal has a dust outlet. This is preferred when the rotary tube seal encloses a very low-lying area. This makes it easy to remove the dust discharged from the rotary tube.

[0037] 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, the rotary tube seal, and the housing. The internal gas supply serves, in particular, to resuspend dust and remove it from the area. For this purpose, the internal gas supply can also be operated in pulses, for example.

[0038] In a further embodiment of the invention, the first sealing surface and / or the second sealing surface comprises a wear plate. The wear plate serves to prevent wear on the first sealing surface and / or the second sealing surface caused by the sealing elements. If necessary, the wear plate can be replaced without impairing the load-bearing capacity of the first sealing surface and / or the second sealing surface.

[0039] In a further embodiment of the invention, the first sealing surface and / or the second sealing surface are designed to be segmented and can be screwed or welded.

[0040] 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 also arranged behind the dust sealing element. The dust sealing element is primarily intended to minimize the escape of dust into the intermediate space. The dust sealing element is preferably annular, preferably with an approximately round cross-section. For example, the dust sealing element comprises a glass fiber fabric. For mechanical reinforcement, the dust sealing element can comprise a metal fabric, particularly on the surface. On the inside, the dust sealing element can also be filled with metal wool, for example, to achieve a comparatively rigid, yet at the same time adaptable outer shape.

[0041] The device according to the invention is explained in more detail below with reference to embodiments shown in the drawings.

[0042] Fig. 1 Simplified overall view

[0043] Fig. 2 first example

[0044] Fig. 3 second example

[0045] Fig. 4 third example

[0046] Fig. 5 Detailed view Fig. 6 first example with wobbling motion

[0047] Fig. 7 fourth example

[0048] The illustrations are purely schematic and not to scale. For simplicity, only a small section is shown.

[0049] Fig. 1 shows a first simplified overall representation. The rotary kiln 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, and the gas flow from the bottom right to the top left. Typically, a combustion device for generating the necessary thermal energy is also arranged in the right-hand housing 20. The rotary kiln 10 itself is often mounted on two or more bearings and is driven by at least one of these bearings, thus causing it to rotate.

[0050] In the following, the usual inclination of the rotary kiln, for example, 4%, is omitted for simplicity. Identical components are provided with the same reference numerals for simplicity. The schematic representations preferably refer to both the inlet side of the rotary kiln and the outlet side of the rotary kiln.

[0051] Shown is a portion of the cross-section perpendicular to the rotational axis of the rotary tube 10, with only a small section of the lower part of the rotary tube 10 and a portion of the housing 20 being shown. The rotary tube seal 50 shown would, in a first approximation, be arranged rotationally symmetrically around the rotational axis of the rotary tube 10.

[0052] Fig. 2 shows a first example in which the first sealing surface 30 runs parallel to the furnace tube 10 and the second sealing surface 40 perpendicular to the axis of rotation of the rotary tube 10. Between the rotary tube 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 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. This makes it possible, on the one hand, to compensate for the inclination of the rotary tube 10 (not shown here). On the other hand, it is possible to arrange a dust outlet 120 at the lowest point in this area, via which the dust, in particular discharged from the rotary tube 10 and settling 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.

[0053] 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 arranged at right angles to the third sealing surface 60, which in turn is arranged parallel to the second visible surface 40. If a wobbling movement of the rotary tube 10 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 thus also ensured, even if the rotary tube 10 deforms and therefore exhibits a wobbling movement.A wobbling motion can cause the rotary tube 10 to tilt in the area shown, so that the first sealing surface 30 and the third sealing surface 60 are no longer exactly plane-parallel. However, this tilt can be compensated for by the round spacer element 100 and the sealing elements 80, so that the sealing effect is maintained.

[0054] To improve the sealing effect, the third sealing surface 60 and the fourth sealing surface 70 each have two circumferential sealing elements 80. To make it easy to 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 spaced from the first sealing surface 30. Here, the spacer element 100 takes over the frictional connection function and, thanks to the round surface, enables good sealing between the first sealing surface 30 and the third sealing surface 60, even if the first sealing surface 30 is tilted. The side elements 92 of the fourth sealing surface 70 are longer and thus take over the frictional connection function, so that a spacer element 100 can be dispensed with.

[0055] Since the annular rotary tube seal 50 preferably partially presses against 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 is not primarily applied to the sealing elements 80, preventing them from unnecessary wear and thus extending their service life. Therefore, the spacer element 100 can also serve for centering. In the example shown, the spacer element 100 is therefore preferably arranged centrally in the third sealing surface 60.

[0056] To optimize the seal, the fourth sealing surface 40 is pressed against the second sealing surface 40 by means of a pressure device 110. The pressure device 110 can be, for example, a tension spring or a pneumatic cylinder. For example, three to thirty-two, preferably four to twenty-four, pressure devices 110 can be present to generate the most uniform force possible.

[0057] Fig. 3 shows a second example, which differs from the first example in particular in that the first sealing surface 30 is mounted 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 correspondingly designed as a cylinder jacket and has a larger diameter than the rotary tube 10. This also results in particular in 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 being formed.

[0058] 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 via 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 tilting, the angle is distributed on both sides, so that the deviation from the plane-parallel arrangement is reduced.

[0059] In Fig. 5, a first sealing surface 30 and a third sealing surface 60 are shown in detail, as shown in the first example in Fig. 2. The fourth sealing surface 70 in the second example shown in Fig. 3 could also be constructed analogously. Firstly, a ring element 82, for example a metal band, is arranged behind the sealing element 80. Force generating devices 84, for example springs, which can be screwed into the third sealing surface 60, press on the ring element 82. This point force is evened out by the ring element 82, so that the sealing element 80 is pressed evenly against the first sealing surface 30. And the position of the force generating device 84, i.e. how far the force generating device 84 is screwed into the third sealing surface, allows the wear of the sealing element 80 to be visually detected from the outside.Alternatively, the force generating device 84 may comprise a measuring device to automatically detect the position and thus the wear.

[0060] Additionally, a gas supply 150 is shown, through which, for example, carbon dioxide or process gas can be introduced into the enclosed volume 140. In particular, this creates an overpressure in the enclosed volume 140 relative to the environment and the furnace tube 10, so that in the event of a leak, this introduced gas escapes. This reliably prevents the penetration of nitrogen, in particular, to the greatest extent possible. At the same time, a leak, for example, due to a defect in a sealing element, can be immediately detected based on the resulting gas flow through the gas supply 150.

[0061] Fig. 6 shows the first example of a rotary tube 10 tilted due to (thermal) deformation, resulting in a wobbling motion. Due to the downward displacement of the right end of the rotary tube 10, the entire rotary tube seal 50 is displaced downward, which is clearly evident from the fact that the fourth sealing surface 70 is no longer centered on the second sealing surface 40. Furthermore, the first sealing surface 30 and the third sealing surface 60 are no longer exactly parallel to one another. However, the sealing effect remains due to the round shape of the spacer element 100 and the pressed-on sealing element 80.

[0062] Fig. 7 shows a fourth example which differs in some respects 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 a sealing element 80, wherein the sealing element 80 is designed as a sealing cord. In order to prevent the sealing cord from sagging, particularly on the underside, mineral wool 160 is arranged beneath the sealing cord. In addition, a flexible surface element 170 is arranged between the fourth sealing surface 70 and the housing 20. This enables the fourth sealing surface 70 to be tilted relative to the second sealing surface 40, and at the same time the combination of the sealing cord and the flexible surface element 170 creates a gas space which can be filled, for example, with a sealing gas.At the same time, the U-shape in a compact design allows a good seal to be achieved between the first sealing surface 30 and the third sealing surface 60 by means of the pressing device 110.

[0063] Reference numeral 10 rotary tube 20 housing 30 first sealing surface 40 second sealing surface 50 rotary tube seal 60 third sealing surface

[0064] 70 fourth sealing surface

[0065] 80 Sealing element 82 Ring element 84 Force generating device 91 Side element 92 Side element

[0066] 100 spacer element

[0067] 110 Pressing device

[0068] 120 Dust outlet 130 Protective device

[0069] 140 enclosed volume

[0070] 150 Gas supply

[0071] 160 mineral wool

[0072] 170 flexible surface element

Claims

Patent claims 1 . Device for the thermal treatment of a mineral material with a rotary kiln, wherein the device has a stationary housing (20) and a rotatable rotary tube (10), wherein the rotary tube (10) and the housing (20) are connected to one another for the direct mass transfer of the mineral material, wherein the rotary tube (10) is rotatably connected to the housing (20), wherein a rotary tube seal (50) is arranged between the rotary tube (10) and the housing (20), wherein the rotary tube seal (50) is not a component of the rotary tube kiln (10) or the housing (20), wherein the rotary tube seal (50) is arranged annularly around the rotary tube kiln (10), characterized in that the rotary tube (10) has a first sealing surface (30), wherein the housing (20) has a second sealing surface (40), wherein the first sealing surface (30) and the second sealing surface (40) are substantially perpendicular to a surface through the axis of rotation of the rotary tube (10). are arranged relative to each other,wherein the rotary tube seal (50) is arranged between the first sealing surface (30) and the second sealing surface (40), wherein the rotary tube seal (50) has a third sealing surface (60) and a fourth sealing surface (70), wherein the third sealing surface (60) and the fourth sealing surface (70) are arranged at right angles to one another and are firmly connected to one another, wherein the first sealing surface (30) is arranged opposite the third sealing surface (60) and the second sealing surface (40) is arranged opposite the fourth sealing surface (70), wherein the first sealing surface (30) and the third sealing surface (60) are ideally plane-parallel, wherein the second sealing surface (40) and the fourth sealing surface (70) are ideally plane-parallel, wherein 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 surface, or a cylindrical surface.

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) are disc-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, wherein the rotary tube seal (50) has a sixth sealing surface, wherein the first sealing surface (30) and the fifth sealing surface are plane-parallel, wherein 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 one first sealing element (80) on the third sealing surface (60), wherein the rotary tube seal (50) has at least one second sealing element (80) on the fourth 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), wherein the rotary tube seal (50) has 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), wherein the first gas supply (150) is designed to supply gas into the volume (140) enclosed by the first sealing surface (30), the third sealing surface (60), the first sealing element (80) and the third sealing element (80), wherein the second gas supply (150) is designed to supply gas into the volume (140) enclosed by the second sealing surface (40), the fourth sealing surface (70), the second sealing element (80) and the fourth sealing element (80).

7. 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), wherein a flexible surface element (170) is arranged between the fourth sealing surface (70) and the housing (20).

8. 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), wherein the first gas supply (150) is designed to supply gas into the volume (140) enclosed by the first sealing surface (30), the third sealing surface (60), the first sealing element (80) and the third sealing element (80), wherein the second gas supply (150) is designed to supply gas into the volume (140) enclosed 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).

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 by a force generating device (84).

12. 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 removal of the side elements (91, 92).

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), wherein the pressing device (110) is fixedly connected to the housing (20) or the foundation, wherein the pressing device (110) is connected via a force-generating pressing element to the third sealing surface (60) or fourth sealing surface (70) which is substantially 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. 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 cardanically attached to 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, wherein the internal gas supply is 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 fabric.

Images