WO1995007956A1

WO1995007956A1 - Slip-ring seal to seal a hot pipe against a casing

Info

Publication number: WO1995007956A1
Application number: PCT/DE1994/001015
Authority: WO
Inventors: Karl May; Hartmut Herm; Karlheinz Unverzagt
Original assignee: Siemens Aktiengesellschaft
Priority date: 1993-09-16
Filing date: 1994-09-05
Publication date: 1995-03-23
Also published as: DE4331556A1

Abstract

The slip-ring seal (2) has a sealing ring (16) secured coaxially to and rotated with the hot pipe (4). A counter-ring (22) is secured to the fixed casing (6) via a compensator (24). During operation, the two faces of the sealing rings (16, 22) slide on each other. To prevent cracks in the sealing ring (16), the latter is secured to the pipe (4) via a bush (32) with a central aperture (34). This bush (32) surrounds a thin ring (36) and a thin pipe section (38) secured to its outer circumference.

Description

description

Mechanical seal for sealing a hot pipe against a housing

The invention relates to a mechanical seal for sealing a rotatable tube against a stationary housing a) with a sealing ring which is connected to the tube, which is arranged coaxially to the tube and which can also be rotated with the tube, b) with a flexible compensator, c) with a mating ring which is connected to the housing via the flexible compensator for compensating for changes in length of the tube, the mating ring having an end sealing surface on an end sealing surface of the sealing ring for sealing the housing against the Tube can be pressed.

Such a mechanical seal is used in a plant for the thermal treatment of waste, for example between the discharge pipe of the pyrolysis device (carbonization drum) and the downstream discharge device from which carbonization gases and carbonization material are withdrawn separately, in particular in a system , which works according to the smoldering process.

The so-called smoldering process has become known in the field of waste disposal. The method and a plant for thermal waste disposal operating according to it are described, for example, in EP-A-0 302 310 and in DE-A-38 30 153. The essential components of the plant for thermal waste disposal using the smoldering-firing process include a smoldering chamber (pyrolysis reactor) and a high-temperature combustion chamber. The smoldering chamber converts the waste that is fed in via a waste transport device into smoldering gas and pyrolysis residues. The smoldering gas and the After suitable processing, pyrolysis residues are fed to the burner of the high-temperature combustion chamber. Molten slag is produced in the high-temperature combustion chamber, which is removed via a fume hood and which, after cooling, is in a glass-like form. The resulting flue gas is fed to a chimney as an outlet via a flue gas line. In particular, a heat recovery steam generator as cooling device, a dust filter system and a flue gas cleaning system are installed in this flue gas line.

As a smoldering chamber (pyrolysis reactor), a rotating, relatively long smoldering drum is generally used, which has a large number of parallel heating pipes on the inside, on which the waste is largely heated in the absence of air. The smoldering drum rotates about its longitudinal axis. The longitudinal axis of the carbonization drum is preferably slightly inclined with respect to the horizontal, so that the solid carbonization material collects at the outlet of the carbonization drum and can be discharged from there via a discharge pipe. When turning, the waste is lifted up through the heating pipes and falls down again. As a result, the transport of the solid material (dust, carbon particles (coke), stones, glass, metal, ceramic parts, etc.) in the direction of the discharge opening of the Schweltro mel is accomplished. A centrally arranged discharge pipe is firmly connected to the smoldering drum and rotates together with the smoldering drum. Through this, the carbonization gas resulting from the waste and the solid material are passed on to a stationary discharge device, essentially a housing with an outlet for carbonization gas and an outlet for solid carbonization material. It is important to have a good seal between the smoldering drum including the discharge pipe and the discharge device, since a certain negative pressure prevails in them and the pyrolysis in the smoldering drum must take place under a lack of oxygen, that is to say under-stoichiometric.

The mechanical seal mentioned above for a Schweltrom¬ mel is known from EP-A-0 431 419 (GR 89 P 3592 E). In this case, a sliding or sealing ring is provided, which is connected to the rotating tube and is arranged coaxially with the latter. A counter ring is also provided, which is connected to the stationary housing of the discharge device via a flexible compensator. This compensator is used to compensate for changes in length of the rotating tube; it consists, for example, of a gas-tight, flexible fabric. It ensures that the counter ring is movably connected to the housing on all sides. The mating ring is pressed with its end sealing surface against an end sealing surface of the rotating sealing ring. As a result, the rotating tube is well sealed against the stationary housing.

It has now been shown that the rotating sealing ring is exposed to a high thermal load. On the one hand, it is attached centrally to the hot rotating discharge pipe and exposed to a temperature of 450 ° C, for example. On the other hand, its outer circumference, in particular as a result of cooling by the rotation, has a temperature of only about 100 to

Assumed 130 ° C. As a result of the tension building up in the sealing ring, cracks may form. Such a crack formation must be prevented in the interest of a long service life.

The invention is therefore based on the object of designing a mechanical seal of the type mentioned in such a way that it can withstand thermal loads practically undamaged.

This object is achieved in that the sealing ring is attached via a box with a central opening on the pipe.

The box assumes the function of extensive thermal decoupling between the hot tube and the rotating sealing ring, in particular if it is made from a thin steel sheet. The rotating sealing ring can have a smaller web height because it does not sit directly on the rotating tube, but is attached at a distance to the outer edge of the can.

Further advantageous configurations are characterized in the subclaims.

Exemplary embodiments of the invention are explained in more detail below with reference to four figures. The same reference symbols are used for the same components. Show it:

1 shows a mechanical seal between a rotating discharge pipe and a stationary discharge device according to the prior art;

Figure 2 is a view of the rotating sealing ring used with a typical temperature distribution;

3 shows a mechanical seal according to the invention using a can and

Figure 4 is a view of the rotating sealing ring used with a typical temperature distribution.

Figure 1 shows a mechanical seal 2 according to the state of the

Technique for sealing a rotating tube 4 against a resting housing 6. The rotation of the tube 4 about its longitudinal axis is characterized by an arrow 8. This tube 4 is specifically the discharge tube or drum tube of a smoldering furnace. It is firmly connected to the heated smoldering drum (not shown) which is loaded with waste and which rotates during operation. In the smoldering drum, the waste is converted into smoldering gases ε and solids f by pyrolysis. The carbonization gases s and the solids f are transferred with the help of the discharge pipe 4 into the housing 6 of a discharge device and are further processed there via separate outlets 10 and 12 for further processing. headed. The rotating drum tube 4 is provided with an insulation 14 on the outside.

The mechanical seal 2 comprises a slide or sealing ring 16 which is welded to the end of the drum tube 4 by means of two weld seams 18, 20. The sealing ring 16 is arranged coaxially to the drum tube 4 and rotates with the drum tube 4. The sealing ring 16 is welded onto the drum tube 4 in the cold state.

The outer end face of the sealing ring 16 faces the end face of a counter ring 22, which is arranged in a stationary manner. This counter ring 22 is attached to a flexible compensator 24 which serves to compensate for changes in length of the drum tube 4 and which in turn is attached to the housing 6 of the discharge device so as to be movable in all directions. The arrangement is such that the compensator 24 centrally surrounds a nozzle 26 of the housing 6. The end of the drum tube 4 is in turn inserted into this connecting piece 26. The sealing ring 22 can be pressed by means (not shown) (pressure springs or pneumatic cylinders) with its end sealing surface against the end sealing surface of the counter ring 16 for the purpose of sealing the housing 6 against the drum tube 4.

The temperature load of the co-rotating sealing ring 16 is shown in FIG. Thereafter, the rotating drum tube 4 has a temperature T] _ of approximately 450 ° C. during operation of the carbonization drum (not shown). As a result, the material temperature T2 of the rotating sealing ring 16 on the tube 4 is likewise approximately T2 = 450 ° C. On the non-insulated outer circumference of the rotating sealing ring 16, however, the material temperature T3 is only approximately T3 = 100 to 130 ° C. This creates 16 different thermal expansions in the sealing ring and thus very high stresses, and the sealing ring 16 can warp or tear. This is indicated by a crack 30. It is important that the formation of such cracks 30 despite the considerable temperature to avoid door differences (T2 - T3). This object is achieved with the mechanical seal 2 according to FIG. 3.

In the following, only those things are described which are different between the mechanical seals 2 of Figure 3 and Figure 1.

According to FIG. 3, the mechanical seal 2 again comprises a sealing ring 16 and a counter ring 22, the end faces of which are pressed against one another. In the present case, however, the inner diameter of the sealing ring 16 does not correspond to the outer diameter of the drum tube 4; the inner diameter is much larger.

According to FIG. 3, the sealing ring 16 is fastened to the pipe 4 via a socket 32 with a central opening 34. Two weld seams 18, 20 are also provided here for fastening. The arrangement is such that the tube 4 is passed through the central opening 34 in the bottom of the can 32. As can be seen from FIG. 3, the can 32 comprises an annular base or ring 36 and a tubular part 38 attached to its outer circumference, which is concentric to the tube 4. This pipe part 38, which is fastened to the sealing ring 16 by means of a weld 40, can also be covered on the outside with insulating material 14. The ring 36 and the pipe part 38 attached to it are thin pieces of material. The tube piece 38 is selected to be thin so that it has a certain elasticity but is nevertheless dimensionally stable. The ring 36 is fastened to the tube 4 by means of the weld seams 18, 20. The two sealing rings 16, 22 can again be made of steel.

A lubricant, for example a suitable, temperature-resistant grease, can be present between the two sealing rings 16, 22. This can be brought through the counter ring 22 through a channel (not shown) to the sealing surfaces. It is also an advantage if at least one of the two sealing surfaces is provided with a lubrication groove 41. This lubrication groove 41, which is intended to receive the lubricant, can be designed in the form of a ring and lie concentrically with the sealing ring 22.

The arrangement of the can 32 between the sealing ring 16 and the tube 4 has the consequence that the tube (drum tube) 4 can expand largely independently of the sealing ring 16. The seal ring web height h of the sealing ring 16 is considerably smaller compared to the embodiment in FIG. 1. This also reduces the thermal stresses mentioned.

This is illustrated once again with the aid of FIG. 4. In the present case, the temperature T 1 is again approximately 450 ° C., and the temperature T 3 measured on the outside is again approximately 100 to 130 ° C. However, only a limited amount of heat is supplied to the sealing ring 16 via the can 32, so that the temperature T2 measured on the inner circumference is only approximately T2 = 200 to 250 ° C. Thus, the temperature difference (T3 - T2) at the sealing ring 16 is only about 70 to 120 ° C., which is considerably lower than in the embodiment according to FIG. that the risk of cracks 30 is significantly reduced or eliminated. In summary it can be said that the mechanical seal 2 shown in FIG. 3 remains low-tension and elastic in all operating states of a carbonization drum.

Finally, it should be emphasized that the application of the mechanical seal 2 is not limited to the gas-tight connection between a discharge pipe 4 and a discharge device 6. Rather, it is used wherever a rotating pipe is sealed against standing case goes. It can therefore also be used, for example, to seal the rotary screw which is customary in a smoldering-firing installation against the smoldering drum or else in the case of the Sealing of the carbonization drum against a heating gas housing, which can be arranged either at one or the other end of the carbonization drum.

Claims

claims

1. Mechanical seal (2) for sealing a rotatable tube (4) against a standing housing (6) a) with a sealing ring (16) which is connected to the tube (4), which is arranged coaxially to the tube (4) and which can be rotated with the tube (4), b) with a flexible compensator (24), c) with a counter ring (22), which with the housing (6) via the flexible compensator (24) to compensate for changes in length of the Tube (4) is connected, the counter ring (22) having an end sealing surface being pressed against an end sealing surface of the sealing ring (16) for sealing the housing (6) against the tube (4), characterized in that the Sealing ring (16) is fastened to the tube (4) via a box (32) with a central opening (34).

2. Mechanical seal according to claim 1, so that the tube (4) is passed through the central opening (34) in the bottom of the box (32).

3. Mechanical seal according to claim 1 or 2, d a d u r c h g e k e n n z e i c h n e t that the box (32) is a ring

(36) and a tubular part (38) fastened thereon to the outer circumference.

4. Mechanical seal according to claim 3, so that the pipe part (38) is covered on the outside with an insulating material (14).

5. Mechanical seal according to one of claims 1 to 4, characterized in that the sealing ring (16) on the tube part (38) and the ring (36) on the tube (4) are welded.

6. Mechanical seal according to one of claims 1 to 5, d a d u r c h g e k e n n z e i c h n e t that the box (32) consists of a steel.

7. Mechanical seal according to one of claims 1 to 6, d a d u r c h g e k e n n z e i c h n e t that the sealing ring (16) and / or the counter ring (22) consists of steel.

8. Mechanical seal according to one of claims 1 to 7, d a d u r c h g e k e n n z e i c h n e t that a lubricant is provided between the sealing ring (16) and the counter ring (22).

9. Mechanical seal according to one of claims 1 to 8, d a d u r c h g e k e n n z e i c h n e t that it has a lubrication groove (40).