LEAST ONE TRANSITION BETWEEN AT LEAST TWO PARTS

WHICH ARE MOVABLE RELATIVE TO ONE ANOTHER

The invention relates to a sealing arrangement for sealing at least one transition between at least two parts which are movable relative to one another, having at least one first sealing device, which sealing device comprises at least one, in particular annular and multipart, sliding ele ment which is arranged on a first part which can be rotated about an axis of rotation, which sealing device comprises at least one sliding element housing which surrounds the sliding element at least partially in the cir cumferential direction with respect to the axis of rotation, and which sealing device comprises at least one, in particular flexible, first pressing means which is arranged between the sliding element and the sliding ele ment housing, and having at least one second sealing device, which seal ing device comprises at least one, in particular annular, sealing means which is arranged on the rotatable first part, and which sealing device comprises at least one sealing means housing which at least partially en compasses the sealing means in the circumferential direction, and to a sealing device for such a sealing arrangement.

The invention further relates to the use of such a sealing arrange ment for sealing the transitions from moving parts to stationary parts, in particular for sealing the product discharge side of a rotary tube kiln, preferably for sealing the product discharge side of a rotary tube kiln for the production of hydrogen fluoride.

Moreover, the invention relates to a method for sealing at least one transition between at least two parts which are movable relative to one another, in particular for sealing rotating drums, tubes or shafts with re spect to stationary housings, comprising the steps of the preamble of Claim 13.

It is known that rotating drums, shafts, tubes or axles can be sealed with respect to an unmoved housing for example by means of an axial sliding ring seal or a radial throttle (stuffing box seal). For this purpose, use is preferably made, in order to seal the transitions, of axial sliding ring seals which act via surface pressure. Sliding ring seals consist essentially of two circular, planar sliding surfaces which are pressed against one another. A radial sliding surface, the so-called counter-ring, is here fixedly connected to the stationary housing, and the actual sliding ring is fastened to the moving part, namely the rotating drum, tube or shaft, and bears by its radial sliding surface against the counter-ring. Pressing elements, for example weights, springs or pneumatic cylinders, distributed on the circumference of the sliding surface of the counter-ring are used to press the two radial sliding surfaces firmly onto one another.

It has been found to be disadvantageous here that axial and radial movements, for example tumbling movements of the drum, tube or shaft, can be absorbed only inadequately. This disadvantage is intensified if ax ial movements of the drum, tube or shaft, caused by displacement or heating of the drum, tube or shaft, are very large.

In the known sealing arrangements, this results in sealing surfaces being reduced or being completely removed. In order to keep this disad vantage small, the sliding surfaces have to be plane-parallel to one an other, which makes construction and configuration of the sealing arrange ment complicated and cost-intensive.

Furthermore, this disadvantage can be reduced by virtue of the fact that the high degree of wear of the parts is compensated for by a high maintenance effort or a high lubricant use, which is cost- and labor-inten sive.

DE 40 35 129 A1 discloses a nongeneric sealing arrangement which features a self-supporting and floating sliding ring seal in which the seal ing surfaces are in form-fitting engagement with one another, have a pro filing and are held under axial pressure.

The object of the invention is to propose a sealing arrangement which has an improved sealing action and an increased service life and in which the maintenance is simpler and thus not so labor- and cost-inten sive.

This object is achieved according to the invention by a sealing ar rangement stated at the outset in that the second sealing device comprises a second pressing means which is arranged between the sealing means and the sealing means housing and by which the sealing means can be or is subjected to a force in the direction of the rotatable first part. As a result, a high sealing action is ensured by the sealing arrange ment according to the invention during axial and/or radial movements of the rotatable first part.

The rotatable first part can be a drum, shaft, tube or axle. In addi- tion to a rotating movement about the axis of rotation, the first part can also perform a movement in the axial direction or a tumbling movement in the radial direction. What is to be understood by radial direction is a direction perpendicular to the axis of rotation.

The rotatable first part and the second part are rotatable relative to one another. It is conceivable here that both the first part and the second part are each rotatable or rotated. However, it is preferable if the second part is rotationally fixed (fixed against a rotational movement) and in particular comprises a fixed housing.

The first pressing means can be a flexible sleeve which can be ar- ranged and/or can be fastened or is arranged and/or is fastened in the sliding element housing, in particular in a receptacle, in a form-fitting and pressure-tight manner and at least partially, preferably completely, encloses the sliding element in particular on its outer side.

The receptacle in the sliding element housing can be formed by a groove in the circumferential direction.

In the sealing arrangement according to the invention, both the slid ing element and the sealing means have a sealing action.

The sliding element can have any desired design in principle, in particular a two-part or multipart design.

The lubrication of the sliding element can occur in principle in any desired manner. For example, lubricant can be added to the sliding ele ment from outside. Moreover, it proves to be advantageous if the sliding element consists, at least on the inner surface facing the rotatable first part, of a self-lubricating material, preferably sintered material such as gray cast iron, gunmetal or bronze. Moreover, self-lubricating materials made of plastic are also conceivable.

The sealing arrangement according to the invention can be applied wherever sealing of transitions from moving parts to stationary parts should occur. Moving parts are considered, for example, to be drums, shafts, tubes, axles or rotors, and stationary parts are considered, for ex ample, to be housings or stators. In particular, the sealing arrangement can be used in all fields in which use is currently made of stuffing box seals, sliding ring seals, labyrinth seals or lamellar seals. Possible appli cation areas which can be mentioned for example are drums, rotary kilns, conveying worms, agitators, pumps, fans, valves, fittings, etc.

The sealing arrangement according to the invention can be used, for example, for sealing the transitions at the entry and exit housing of a ro tary kiln, in particular at its product discharge side.

It proves to be advantageous that at least one sealing means and/or that at least one sliding element bear/bears against the rotatable first part in a form-fitting manner.

In addition, it proves to be advantageous if the sealing means bears against the rotatable first part by an inner side facing the axis of rotation and/or bears against the sliding element by at least one radial end face.

As a result, the sealing means is held at least on one side by the sliding element against axial slipping.

In principle, it is conceivable that the sealing means bears against the sliding element by both end faces. However, it is preferred if the seal ing means bears on one side against a sliding element and on the other side against the second part.

The sealing means can be formed in principle in any desired manner and comprise, for example, a one-piece sealing element. Moreover, it proves to be advantageous if the sealing means comprises at least one packing, wherein the packing can comprise one or more packing rings. Moreover, it proves to be advantageous if the sealing means housing is designed as a stuffing box housing.

In a further development of the invention, it proves to be advanta geous if the second pressing means can be or is arranged directly on the sealing means, or if the second pressing means can be or is arranged indi rectly on the sealing means, in particular if a separating element, such as a split ring, is arranged between the second pressing means and the seal ing means.

The first and second pressing means can be a sleeve which at least partially engages around the sliding element or sealing means in the cir cumferential direction. For example, the first and/or the second pressing means can be formed from half-shells. The first pressing means can be a flexible, pressure-, temperature- and chemical-resistant material, preferably a high-temperature-resistant elastomer, such as hydrofluorocarbon elastomer (Viton) or rubber.

Moreover, the first pressing means can be arranged in any desired manner in the sliding element housing. However, it proves to be advanta geous if the first pressing means is vulcanized onto the sliding element housing.

The sliding element housing can be formed from any desired mate rial, in particular from a metal. It proves to be advantageous if the seal- ing arrangement has a first setting device for the first pressing means and/or a second setting device for the second pressing means, by means of which an, in particular mechanically, pneumatically and/or hydrau lically induced, force acts on the sliding element and/or on the sealing means.

In principle, the first and/or the second pressing means can be of similar design or action. In particular, the force of the first pressing means and of the second pressing means can be able to be set mechani cally, pneumatically or hydraulically. However, it proves to be advanta geous if the first pressing means can be filled by the first setting device with a fluid, with the result that said pressing means can be tensioned particularly in the radial direction. In such a case, the first setting device makes it possible to set a physical variable such as volume, mass flow and/or pressure of the first pressing means. The fluid can comprise a gas, a liquid or both parts made up of gas and parts made up of liquid, in par- ticular air, nitrogen, hydrogen, a noble gas or mixtures of these sub stances.

The pressure of the first pressing means is preferably between 0.1 to 0.3 bar, preferably between 0.1 to 0.2 bar, preferably 0.15 bar.

In principle, the second setting device can be designed identically or similarly to the first setting device, in particular interacting mechani cally or hydraulically with the sealing means. However, it proves to be advantageous if the second pressing means comprises a spring element, in particular a compression spring, and/or the second setting device com prises a setting means, such as a piston-screw arrangement. In this case, the force which can be set on the sealing means is mechanical. In the further development of the last-stated concept of the inven tion, it proves to be advantageous if the setting means has an externally threaded portion and/or the sealing means housing has an internally threaded bore, which corresponds in particular to the externally threaded portion, and if a rotation of the setting means comprises a compression or relaxation (expansion) of the second pressing means designed as a spring element.

The setting means can have an externally threaded portion and be arranged on the sealing means housing, wherein the sealing means hous- ing has a threaded bore. The interaction between the externally threaded portion of the setting means and the threaded bore in the sealing means housing causes a movement of the setting means in the direction of the sealing means. As a result, the second pressing means designed as a spring element is tensioned. A rotation of the piston-screw arrangement in the direction of the rotatable first part leads to an increase of the con tact pressure on the sealing means and thus to an increase of the contact pressure of the sealing means on the rotatable first part. A rotation of the setting means in the opposite direction leads to a reduction of the contact pressure.

Furthermore, there can be provided a piston against which the spring element bears on one side. The piston can be supported directly on the sealing means or lie on a separating element, which is arranged be tween the sealing means and piston, and thus act indirectly on the sealing means.

In order to increase the stability of the arrangement, it proves to be advantageous if the sealing means housing has, in particular in the con tinuation of the axis of the internally threaded bore, a guide in which there is arranged at least the piston which can be or is connected to the second pressing means designed as a spring element. It is possible in this way that only the spring element is arranged between the setting means and the piston, which spring element can substantially take up only forces in the direction of its longitudinal extent.

In a further development, there is provision that the internally threaded bore is arranged on a web which extends in particular parallel to the axis of rotation. In order to allow a lubrication and/or an additional lubrication of the sealing means and/or of the sliding element, it proves to be advanta geous if the sealing means housing and/or the sliding element housing comprise/comprises at least one bore for feeding lubricant and/or barrier agent to the sealing means and/or the sliding element. As a result, wear of the sealing arrangement can be further reduced.

Moreover, it proves to be advantageous if at least one of the at least one first sealing device and at least one of the at least one second sealing device can be or are fastened to one another, in particular in a form-fit- ting and/or releasable manner, and/or if at least one of the at least one first sealing device and/or at least one of the at least one second sealing device have/has a radially extending surface which can be or is sealingly fastened to the second part with respect to which the first part can be or is moved relatively. As a result, the sealing action of the sealing arrange- ment is further increased.

The first sealing device and/or the second sealing device can be connected to the second part in a rotationally fixed manner, in particular by means of welding, adhesive bonding and/or screwing. If the first seal ing device and/or the second sealing device are/is screwed to the second part, they/it are/is fastened releasably to the second part. In such case, the sealing arrangement can be removed again from the second part and maintained in a simple manner.

In order to further improve the fastening of the second sealing de vice to the first sealing device, it proves to be advantageous if the second sealing device has a projection which engages behind the first sealing de vice, as viewed radially, and is thus centered in the direction of the first part.

In principle, it is conceivable that the sealing arrangement has only one first sealing device and only one second sealing device. Moreover, it is preferable if the sealing arrangement has a first sealing device which is arranged between two second sealing devices. This makes it possible to achieve particularly good sealing by the sealing arrangement.

Moreover, the object is achieved by a sealing arrangement accord ing to the invention having one or more of the aforementioned features, having at least one, in particular annular, sliding element which is ar- ranged on the rotatable first part and which has at least one sliding ele ment housing which at least partially encompasses the sliding element in the circumferential direction and on which the second sealing device comprises a second pressing means which is arranged between the seal ing means and sealing means housing, and the sliding element and/or the sealing means can be or are/is subjected to a force in the direction of the rotatable first part.

Moreover, the object is achieved by a method for sealing at least one transition between at least two parts which are movable relative to one another, in particular for sealing rotating drums, tubes or shafts with respect to stationary housings, comprising the following steps:

a) arranging a second sealing device, which sealing device comprises at least one, in particular annular, sealing means which is arranged on a first part which can be rotated about an axis of rotation, and which sealing device comprises at least one sealing means housing which at least partially encompasses the sealing means in the cir cumferential direction, on the rotatable first part;

b) where appropriate, fastening the second sealing device, in particular the sealing means housing, to a second, in particular positionally fixed, part;

c) arranging a first sealing device, which sealing device comprises an, in particular annular and multipart, sliding element which is ar ranged around the rotatable first part, which sealing device com prises a sliding element housing which partially surrounds the slid ing element at least in the circumferential direction, and which seal ing device comprises an, in particular flexible, first pressing means which is arranged between the sliding element and sliding element housing, on the rotatable first part;

d) where appropriate, fastening, in particular fastening in a form-fit- ting and releasable manner, the first sealing device to the second sealing device;

e) setting a pressing force of the first pressing means;

in which, in a step according to the invention, the following occurs: f) setting a pressing force of a second pressing means of the second sealing device. In a further development of the method, it proves to be advanta geous if a pressing force by which the sealing means bears against the first part is set by a second setting device and/or the pressing force by which the sliding element bears against a first part is set by a first setting device.

Finally, it proves to be advantageous if the pressing force of the sealing means is increased or reduced mechanically and/or if the pressing force of the sliding element is increased or reduced pneumatically.

The sealing arrangement according to the invention, the sealing de- vice according to the invention and the method according to the invention for sealing a transition between at least two parts which are movable rel ative to one another proves to be advantageous in multiple respects:

By virtue of the“floating” mounting of the sealing means and of the sliding element, it is possible to absorb and compensate for large radial fluctuations and tumbling movements of the movable first part without the sealing action of the sealing arrangement being compromised. In par ticular, radial fluctuations of a number of millimeters, for example 3-5 mm, can be compensated for in this way. Moreover, radial tolerances and axial length expansions on account of temperature fluctuation can be compensated for in a simple manner.

Moreover, the sealing arrangement allows radial forces to be trans mitted from the moving part to the second part.

Furthermore, the action of the first pressing means provides contin uous centering of the fixed second part, in particular even during opera- tion of the movable first part. Here, a high sealing action is always pro vided independently of the operation of the movable first part in spite of a movement in the radial or axial direction.

The arrangement of the first sealing device directly on a second sealing device makes possible a situation in which the individual compo- nents of the two sealing devices support one another, in particular against a movement in the axial direction. Consequently, by comparison with known sealing arrangements, it is possible to save on components, in par ticular sealing means glands, with the result that the sealing arrangement is of simpler construction. The sealing arrangement according to the invention can be used, for example, for sealing the transitions at the entry and exit housing of a ro tary kiln.

In one embodiment, the product discharge side of a rotary tube kiln is sealed by the sealing arrangement according to the invention.

In a further embodiment, a rotary tube kiln which is used for the production of hydrogen fluoride is sealed by the sealing arrangement ac cording to the invention on the product space side.

Further features, details and advantages of the invention will emerge from the appended patent claims, from the graphic illustration and the following description of two preferred embodiments of the seal ing arrangement according to the invention.

The invention will be explained in more detail below by way of ex ample.

In the drawing:

FIG. 1 shows a schematic sectional view of a first exemplary embodi ment of the sealing arrangement according to the invention, having a first sealing device and having a second sealing de vice.

FIG. 2 shows a schematic sectional view of a second exemplary em bodiment of the sealing arrangement according to the inven tion, having a first sealing device and having two second seal ing devices.

FIG. 1 shows a first exemplary embodiment of a sealing arrange- ment according to the invention that is provided overall with the refer ence sign (2). The sealing arrangement (2) is suitable for sealing at least one transition between at least two parts (4) and (6) which are movable relative to one another. Here, a first part (4) is rotatable about an axis of rotation (8), and a second part (6) is fixed against a rotational movement. The sealing arrangement (2) has a first sealing device (10) and a second sealing device (12). The first sealing device (10) consists of a sliding ele ment (14), of a sliding element housing (16) which encompasses the slid ing element (14), and of a first pressing means (18) which is arranged be tween the sliding element (14) and the sliding element housing (16).

The second sealing device (12) consists of a sealing means (20) which bears against the moving part (4), of a sealing means housing (22) which at least completely surrounds the sealing means (20), and of a sec ond pressing means (24) which is arranged between the sealing means (20) and the sealing means housing (22). In the exemplary embodiment which can be seen in FIG. 1, the second sealing device (12) is fastened to the second part (6) by means of screwing. Moreover, the first sealing device (10) is fastened to the second sealing device (12) via a projection (26) on the sealing means housing (22).

The first sealing device (10) comprises a first setting device (30) having a bore (28). The first setting device (30) allows a fluid to be fed to, or removed again from, the first pressing means (18) through the bore (28). As a result, the pressure by which the first pressing means (18) acts on the sliding element (14) can be increased or can be reduced. The slid ing element (14) bears by an end side against the sealing means (20) and thereby retains it against an axial displacement parallel to the axis of ro- tation (8). The sealing means (20) is held by the second part (6) against an axial displacement on the side facing away from the sliding element (14).

The sealing means (20) bears on one side against the movable first part (4) and, on the side facing away from the movable first part (4), can be subjected to a force by the second pressing means (24).

The force by which the second pressing means (24) acts on the seal ing means (20) can be set by a second setting device (32) which com prises a setting means (34). In the embodiments of the sealing arrange ment (2) that are illustrated in the figures, the second pressing means (24) comprises a spring element (36). The spring element (36) is sup ported on one side on the setting means (34) and on the other side on a piston (38).

A separating element (40) is arranged between the piston (38) and the sealing means (20). In the embodiments shown, this is formed by a split ring.

In order to fasten the second setting device (32) to the sealing means housing (22), the latter has a web (42), the projection (26) being formed on the sealing means housing (22).

The web (42) has an internally threaded bore (46) which is formed in a complementary manner to an externally threaded portion (48) of the setting means (34). In the sealing means housing (22) there is incorpo rated a guide (50) in which the piston (38) of the second setting device (32) is arranged.

The mode of operation of the first exemplary embodiment, which can be seen in FIG. 1, of the sealing arrangement (2) according to the in vention is described below:

In order to seal the transition between at least two parts (4) and (6) which are movable relative to one another, a first sealing device (10) and a second sealing device (12) are arranged on the movable first part (4). For this purpose, a sealing means (20) of the second sealing device (12) and a sliding element (14) of the first sealing device (10) are pushed onto the movable first part (4). The sliding element (14) and the sealing means (20) here bear against the movable first part (4) in a form-fitting manner.

On the side of the sealing means (20) that faces away from the mov- able first part (4), a separating element (40) is pushed on. Supported on the latter, via the piston (38), is the second pressing means (24) designed as a spring element (36). Here, the piston (38) is arranged in the guide (50) of the sealing means housing (22).

On the side of the spring element (36) that faces away from the pis- ton (38), the spring element (36) is supported with respect to the setting means (34). The latter is arranged with its externally threaded portion (48) meshing with the internally threaded bore (46) in the web (42) of the sealing means housing (22).

In order to increase the contact pressure of the sealing means (20) on the movable first part (4), the setting means (34) is rotated in such a way that the spring element (36) is compressed. As a result, the pressure on the sealing means (20) is increased via the piston (38) and via the sep arating element (40).

The first pressing means (18) is arranged on the side of the sliding element (14) that faces away from the movable first part (4). Said first pressing means is surrounded on the other side by the sliding element housing (16). The pressing means can be set by the first setting device (30), or the pressure of the first pressing means (18) can be set, by means of the bore (28) in the sliding element housing (16). Here, in order to in- crease the pressure on the sliding element (14), a fluid is filled into the first pressing means (18) via the bore (28) or, in order to reduce the pres sure, a fluid is removed from the bore (28).

The sliding element housing (16) is fastened to the second sealing device (12) via the projection (26) which is formed on the sealing means housing (22).

As a result, the sliding element housing (16) and the sealing means housing (22) are fastened in a rotationally fixed manner via the screw connection on the second part (6).

FIG. 2 shows a second exemplary embodiment of the sealing ar- rangement (2) as per FIG. 1, in which a second sealing device (12) is ad ditionally provided. Identical parts are provided with identical reference signs, and therefore, to avoid repetition, reference is made to the descrip tion thereof in FIG. 1.

Moreover, FIG. 2 shows a run-off apron (52) which is arranged on the movable first part (4) at a distance from the sealing arrangement (2).

If, for example, the sealing arrangement (2) is used for sealing the drum of a rotary kiln, the radial forces occurring during the heating phase, occasioned by the radial displacement of the drum axis, are trans mitted by the first sealing device (10) to the exit housing, which is fas- tened with disk springs, or to the stuffing box housing of the second seal ing device (12) The radial forces are thus taken up only by the disk springs themselves and not by the stuffing box seal, in particular not by the packing rings.

In a preferred embodiment of the invention, the product discharge side of a rotary tube kiln for the production of hydrogen fluoride is sealed by the sealing arrangement (2). The rotary tube kiln has a length of 30 m. During the heating phase of the drum, length expansions of up to 150 mm are taken up and compensated for by the sealing arrangement (2) without problems. A flexible sleeve is pressed with a contact pressure of 0.15 bar onto the sliding element (14) designed as a sliding ring. The multipart sliding ring has its inner surface arranged in a form-fitting manner around the rotating drum, a radial sealing surface of the sliding ring bearing against the stationary part (exit housing). The flexible sleeve which encloses the sliding ring is charged with compressed air via the in- lets in the sleeve housing and pressed onto the sliding ring. Both an axial and a radial sealing action is thus achieved, since the flexible sleeve also acts in the direction of the exit housing. In order to intensify the sealing action and to secure the sliding ring against axial displacement, a stuffing box seal is mounted so as to bear against the sliding ring, fixed with fas tening elements and releasably connected to the sleeve housing and thus also to the exit housing.

The features of the invention which are disclosed in the above de scription, in the claims and in the drawing may be essential both individ ually and in any desired combination in the realization of the invention in its various embodiments.

List of reference signs

2 sealing arrangement

4 rotatable first part

6 fixed second part

8 axis of rotation

10 first sealing device

12 second sealing device

14 sliding element

16 sliding element housing

18 first pressing means

20 sealing means

22 sealing means housing

24 second pressing means

26 projection

28 bore

30 first setting device

32 second setting device

34 setting means

36 spring element

38 piston

40 separating element

42 web

46 internally threaded bore

48 externally threaded portion

50 guide

52 run-off apron