EP3034784A1 - Cooling means for flow engines - Google Patents

Abstract

The invention relates to a Umlenkleiteinrichtung (26) in the labyrinth seal (25) in the large intermediate bottom (19) to deflect the leakage vapor in the circumferential direction (28), thereby cooling in the relief groove (16, 17) in the medium-pressure inflow region (12). to reach.

Description

The invention relates to a turbomachine, in particular a steam turbine, comprising a rotatably mounted rotor and a housing arranged around the rotor, wherein between the rotor and the housing a first flow channel pointing in a first direction and a second flow channel pointing in a second flow direction is arranged between the first and the second flow channel a labyrinth seal comprising a plurality of tips is arranged.

Turbomachines in the context of this invention are, for example, steam turbines, gas turbines or compressors, the invention preferably referring to steam turbines. Turbomachines are characterized by a flow medium. Hydraulic turbines, steam and gas turbines, wind turbines, centrifugal pumps and centrifugal compressors as well as propellers are summarized under the collective term turbomachinery. All of these machines have in common that they serve the purpose of extracting energy from one fluid in order to drive another machine, or vice versa, to supply energy to a fluid in order to increase its pressure. In turbomachines, the energy conversion is indirect and preferably takes the path over the kinetic energy of the fluid.

In turbomachines, such. B. in steam turbines, flows during operation, a flow medium in a main flow direction, which corresponds substantially to the direction of the axis of rotation. The flow medium should ideally only flow through a so-called flow channel, which has so-called guide vanes and rotor blades. Usually, the flow channel is formed of different successively arranged guide and moving blades. The flow medium passes through the flow channel past the vanes and blades, the kinetic energy into rotational energy is converted, which leads to a rotation of the rotor. As movement of the rotor takes place in a housing, there are gaps between the housing and the rotor which should be made as small as possible. However, gaps can not be avoided, resulting in undesirable flow through the gaps. The undesirable flow results from the main flow, with a part branching off from the main flow and flowing through the gap. This gap flow can be referred to as secondary flow, wherein it is the goal in any design of a turbomachine to keep the secondary flow as low as possible. Therefore, various approaches exist to minimize secondary flow. A first approach is to place so-called sealing lips between the rotating and fixed components. The sealing lips are arranged rotationally symmetrical and act as a kind of barrier to the secondary flow. Thus, a secondary flow substantially flowing to the main flow is decelerated.

There are steam turbines known as an embodiment of a turbomachine having two floods. This means that such a steam turbine has a first flow channel and is arranged opposite to a second flow channel. Such steam turbines are characterized by two inflow regions. A first inflow region for the first flow channel and a second inflow region for the second flow channel. Furthermore, such a steam turbine is characterized in that a common rotor has a blading region for the first flow channel and a second blading region for the second flow channel. Between the Beschaufelungsbereichen a so-called intermediate floor is arranged, which has a surface which must be arranged as close as possible to a housing arranged around the rotor. A gap between the intermediate bottom and the housing should be as small as possible, because a steam flowing in in the first inflow region can partially flow through this gap and into the second inflow region of the second flow channel can flow. Therefore, such gaps are performed with so-called labyrinth seals. Labyrinth seals have so-called tips, which are arranged both on the surface of the rotor and on the inner surface of the housing. Labyrinth seals are known in the art and need not be further elaborated here.

Furthermore, rotors have so-called relief grooves in the inflow region. Such relief grooves are characterized by a smaller radius. For the aforementioned steam turbines, the shaft temperatures in the relief groove are limiting for the life of the shaft. Furthermore, the shaft temperature is also limiting for the transmissive power of the shaft. Therefore, great efforts are made to lower the temperature as much as possible. At this point, the invention begins, whose task is to provide a further way to reduce the temperature in the relief groove.

This problem is solved by a turbomachine, in particular a steam turbine, comprising a rotatably mounted rotor and a housing arranged around the rotor, wherein between the rotor and the housing a first flow channel pointing in a first direction and a second flow channel pointing in a second flow direction are arranged , wherein between the first and the second flow channel a multi-tip labyrinth seal is arranged, seen in the second flow direction after a last tip a Umlenkleiteinrichtung is arranged, which is designed such that a flowing in the axial direction in the labyrinth seal leakage at least partially into Circumferential direction of the rotor is deflected.

With the invention, therefore, a cooling option is offered which is comparatively inexpensive to manufacture and is characterized by a Umlenkleiteinrichtung. The Umlenkleiteinrichtung generates a twist of the flowing leakage steam in Area of the relief groove and can further lower the temperature at the shaft surface in the relief groove. In this case, the leakage steam flowing out of the labyrinth seal is deflected by the deflection guide into the shaft rotation direction.

Thus, with the invention, a high kinetic energy of the leakage steam at the outlet of the labyrinth seal of a large intermediate floor is utilized and utilized for cooling possibilities.

By reducing the shaft temperature at the surface of the relief groove, the transmissible power through the relief groove can be increased. Furthermore, the achievable lower temperature in the relief groove may also result in a cooling action on a first blade groove. This would lead to a lower utilization and thereby to an improvement in the blade design.

Advantageous developments are specified in the subclaims.

In a first advantageous development, the deflecting device has a plurality of deflecting elements distributed on the circumference. This enhances the effect by distributing an appropriate number of diverters around the circumference. The Umlenkleiteinrichtung has the task to redirect the flowing in the labyrinth seal leakage steam flow and thereby to generate a twist, which causes the leakage steam is deflected in a shaft rotation direction. The number of deflecting elements should be chosen appropriately.

In a further advantageous embodiment, the deflecting elements are bent. For flow-related reasons, it is advantageous to take into account a bending of the deflecting elements in order thereby to have the lowest possible flow losses. The bow can be a parabolic Contour. It is also conceivable a circular contour.

In a further advantageous development, the deflection elements are initially designed to be directed in the axial direction, which points in the direction of rotation, and then the deflection elements have an arc which points in the circumferential direction.

Thus, in an advantageous development, the deflection elements are designed such that a deflection takes place by 90 °. This is to be understood as meaning that the leakage steam flow essentially flows in the axial direction and is deflected by 90 °, which essentially corresponds to the circumferential direction.

The deflecting elements can be formed profiled in an advantageous development. This means that the deflecting elements have a guide-blade-shaped contour. The Leitschaufelförmige contour causes a flow is deflected and accelerated, resulting in the aforementioned effect of the cooling.

In an advantageous embodiment, the deflection elements are designed as a stator blade stage.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following description of the embodiments which will be described in connection with the drawings.

Embodiments of the invention are described below with reference to the drawing.

This is not intended to represent the embodiments significantly, but the drawing, where appropriate for explanation, executed in a schematized and / or slightly distorted form. With regard to additions to the teachings directly recognizable in the drawing reference is made to the relevant prior art.

Figur 1

eine Querschnittsansicht einer Strömungsmaschine,

Figur 2

eine Querschnittsansicht eines vergrößerten Teils aus Figur 1,

Figur 3

eine Querschnittsansicht einer erfindungsgemäßen Anordnung,

Figur 4

eine Draufsicht auf die erfindungsgemäße Anordnung.

Show it:

FIG. 1

a cross-sectional view of a turbomachine,

FIG. 2

a cross-sectional view of an enlarged part FIG. 1 .

FIG. 3

a cross-sectional view of an arrangement according to the invention,

FIG. 4

a plan view of the inventive arrangement.

The FIG. 1 shows a steam turbine as an embodiment of a turbomachine and has an outer housing 2, which is arranged around a rotor 3 which is rotatably mounted about a rotation axis 4. To the rotor 3, an inner housing 5 is arranged. The steam turbine 1 has a high-pressure part 6 and a medium-pressure part 7. The high-pressure part 6 has a high-pressure inflow region 8, through which a high-pressure fresh steam flows. The high pressure fresh steam then flows through first flow channel 10 aligned in a first direction 9, which may also be referred to as a high pressure flow channel. The thermal energy of the steam in the first flow channel 10 is converted into rotational energy of the rotor 3. The steam then flows out of the high-pressure outflow region 11 and from there, if necessary, to a reheater (not shown). Thereafter, the vapor flows as Mitteldruckeinströmdampf in a Mitteldruckeinströmbereich 12. After flowing into the Mitteldruckeinströmbereich 12, the steam flows in a pointing in a second direction 13 second flow channel 14. After the second flow channel 14, the steam flows through a Mitteldruckausströmbereich 15 out of the turbomachine. The rotor 3 has in the region of the Hochdruckeinströmbereichs 8 a Relief groove 16, which can be characterized in that the rotor 3 at this point in a certain axial region has a smaller radius than the area in front and behind. Likewise, in the region of the medium-pressure inflow region 12, the rotor 3 likewise has a relief groove 17, which can likewise be characterized in that the rotor 3 has a smaller radius in a certain axial length than the rotor 3 before the relief groove 17 and behind the relief groove 17 in FIG the second direction 13 seen from. In operation, a live steam flows in the Hochdruckeinströmbereich 8 and flows for the most part through the first flow channel 10, which is formed with guide and blades not shown. An undesirably small part of the high pressure fresh steam flows through a gap between the inner housing 5 and the rotor 3 in a central region 18. In the central region 18, the rotor 3 has a radius of a certain length and forms a so-called large intermediate bottom 19. The gap between the inner housing 5 and the large intermediate bottom 19 should be formed as vapor-tight as possible and therefore has, as in FIG. 2 shown, a labyrinth seal 25 on. The labyrinth seal 25 comprises a plurality of labyrinth seal segments 20, which are resiliently arranged in labyrinth seal grooves 21. The labyrinth seal segments 20 can thus be moved in a radial direction 34. On the surface of the large intermediate bottom 19, as is customary with labyrinth seals 25, so-called tips 22 are arranged. The tips 22 are also referred to as sealing lips or the like. In contrast, in the labyrinth seal segment 20, a tip 23 or sealing lip is likewise arranged. In an axial direction 24, the tips 22 and 23 are formed sequentially, which is in the FIG. 3 again shown separately.

The FIG. 3 shows an arrangement according to the invention. The FIG. 2 however, shows an enlarged section FIG. 1 namely the part of the turbomachine 1 marked with the oval FIG. 1 represented, the Medium pressure steam from the Mitteldruckeinströmbereich 8 pass through the gap through the labyrinth seal 25 to the Mitteldruckeinströmbereich 12. This leakage should be kept as small as possible. In any case, the leakage current flowing into the relief groove 17 has a comparatively high temperature, which can lead to damage to the rotor 3 in the relief groove 17. According to the invention this is prevented here, as in FIG. 3 can be seen, a Umlenkleiteinrichtung 26 is arranged after a last tip 27 and which is formed such that a flowing in the axial direction 24 leakage steam is at least partially deflected in the circumferential direction 28 of the rotor. The Umlenkleiteinrichtung 26 has a plurality of arranged in the circumferential direction 28 deflecting elements 29. These deflecting elements 29 can be designed bent. This means that the deflecting elements 29 are initially designed to be straight in the axial direction 24 and then have an arc 30 which finally points in the circumferential direction 28 into an end region 31. The deflection elements 29 are in this case designed such that the deflection takes place by 90 °, which means that the deflection elements 29 are first formed in the axial direction 24 parallel in an initial region 32 and are formed in the end region 31 parallel to the circumferential direction 28. In this case, in alternative embodiments, the end region 31 may not necessarily be formed parallel to the circumferential direction 28. The end portion 31 and the circumferential direction 28 may be inclined by an angle α (where α is between 0 ° and 40 °) to each other.

In alternative embodiments, the baffles 29 may be profiled, that is, in a cross-sectional view (not shown), the baffles have a vane shape and accelerate the flow that is between the baffles.

By accelerating the leakage steam, the kinetic energy increases and the temperature drops. Thus, the temperature in the relief groove 17 is reduced. In a first Embodiment, the deflected leakage vapor may be mixed with a medium pressure fresh steam flowing through the medium pressure inflow region 12. In further embodiments, the turbomachine 1 has a diagonal ring 33, which acts as a first guide blade stage and deflects the medium pressure fresh steam directly into the second flow region 14, without causing a vapor to the relief groove 17. In an alternative embodiment, a so-called swirl cooling may be considered in the diagonal ring 33, which flows a vapor from the medium-pressure inflow region into the relief groove 17, which vapor has cooled by the swirl cooling. The diagonal ring 33 has for this purpose a plurality of nozzles, which represents a fluidic connection between the Mitteldruckeinströmbereich 12 and the relief groove 17.

Although the invention has been further illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (8)

Turbomachine, in particular a steam turbine (1), comprising a rotatably mounted rotor (3) and a housing (2, 5) arranged around the rotor (3),
wherein a first flow channel (10) pointing in a first direction (9) and a second flow channel (14) pointing in a second direction (13) are arranged between the rotor (3) and the housing (2, 5),
wherein between the first (10) and second (14) flow channel a labyrinth seal (25) comprising a plurality of tips (22, 23) is arranged,
characterized in that
In the second flow direction (13), after a last tip (27), a deflecting guide (26) is arranged, which is designed so that a leakage steam flowing in the labyrinth seal (25) in the axial direction (24) at least partially in the circumferential direction (28 ) of the rotor (3) is deflectable. Turbomachine according to claim 1,
wherein the Umlenkleiteinrichtung (26) has a plurality of circumferentially distributed deflecting elements (29). Turbomachine according to claim 2,
wherein the deflection elements (29) are designed bent. Turbomachine according to claim 2 or 3,
wherein the deflecting elements (29) are initially directed in the axial direction (24) and then have an arc pointing in the circumferential direction (28). Turbomachine according to one of claims 2 to 4,
wherein the deflection elements (29) are formed such that a deflection takes place by 90 °. Turbomachine according to one of the preceding claims,
wherein the deflection elements (29) are formed profiled. Turbomachine according to claim 6,
wherein deflecting elements (29) are profiled in such a way that a flow is deflected and accelerated. Turbomachine according to claim 7,
wherein the deflecting elements (29) form a vane stage.

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