The invention relates to a turbomachine, in particular a steam turbine comprising an outer housing, an inner housing which is arranged inside the outer housing, a rotor which is rotatably mounted within the inner housing, a thrust compensation piston which is integrally formed with the rotor, a labyrinth seal between the Thrust compensation piston and the inner housing.
Modern steam turbines are usually designed with multiple shells and are divided into high-pressure, medium-pressure and low-pressure sub-turbines. There are embodiments in which the respective turbine sections are arranged in housings designed separately from one another. However, embodiments are also known in which the high-pressure and medium-pressure turbine sections are arranged in a housing. However, embodiments are also known in which the medium and low pressure turbine sections are arranged in their own individual housing.
Combined high and medium pressure turbine sections can be designed with multiple shells. Essential components here are the rotor, the inner housing arranged around the rotor and the outer housing arranged around the inner housing. During operation, there is steam in the steam space between the inner and outer housing. The relaxed steam from the medium-pressure part of the turbine section flows around the inner casing. The hot steam should be distributed as uniformly as possible around the inner housing in order to avoid warping as a result of different thermal stresses.
If the rotor blades of the high and medium pressure turbines generate a significantly high axial thrust on the rotor, a compensating piston must be used to compensate for this axial thrust. This equalizing piston is flowed with hot high-pressure exhaust steam mixed with medium-pressure inlet steam. As a rule, the compensating piston is as small as possible from the inner housing. There are seals between the balance piston and the inner housing. However, it is almost unavoidable that the hot high-pressure exhaust steam that flows on the compensating piston flows between the compensating piston and the inner housing into the steam space between the inner housing and the outer housing and is mixed with the medium-pressure exhaust steam. This means that hot leakage steam emerges from the labyrinth seal of the compensating piston and is supplied with the cooling medium-pressure exhaust steam flowing around the inner housing.
However, this mixture is not homogeneous, which means that different hot strands are formed which can heat up and bend the inner housing on one side. As a result, there is a risk that the blading, which consists of rotor blades, could come into contact with stationary parts such as the inner casing. It is also quite conceivable that radial clearances will be expanded. However, this reduces the efficiency of the steam turbine.
In order to take this effect into account, one solution is to increase the radial clearances in order to avoid rubbing in any case.
However, this leads to a reduction in efficiency.
This is where the invention begins. The object of the invention is to achieve a more homogeneous temperature distribution within the steam turbine.
This object is achieved by a turbomachine, in particular a steam turbine, comprising an outer housing, an inner housing which is arranged inside the outer housing, a rotor which is rotatably mounted within the inner housing, a thrust compensation piston which is integrally formed with the rotor, a labyrinth seal between the thrust compensation piston and the inner housing, wherein means are arranged in the labyrinth seal, which are designed for deflecting a vapor located in the labyrinth seal.
It was recognized that the steam emerging from the labyrinth seal has a swirl. This twist prevents a homogeneous distribution of the steam in the inner housing. Hot strands on one side of the inner housing can accumulate. This leads to a warping as a result of different temperature distributions. According to the invention, means in the form of twist breakers are now arranged at the end of the labyrinth seal. This avoids the swirl of the labyrinth flow and achieves a symmetrical flow around the inner housing with steam.
With the measure according to the invention, it is therefore not necessary to take into account an additional radial play safety allowance. This increases the turbine efficiency. Due to the homogeneous temperature distribution, the course of the strands through the steam space can be controlled more precisely, thus increasing the operational reliability of the system.
Advantageous further developments are given in the subclaims.
In a first advantageous development, the rotor is aligned along an axis of rotation and the means are designed in such a way that the deflection of the steam takes place essentially in the direction of the axis of rotation. This means that the means can be designed as a diffuser which deflects the leakage steam between the compensating piston and the inner housing in the direction of the axis of rotation. This completely avoids the twist that leads to disruptive different strands and different temperature distributions.
The means are advantageously cast in the inner housing. Alternatively, the means can also be screwed onto the inner housing. This means that the funds can be installed and removed more quickly.
In an alternative embodiment, the means could advantageously be arranged in a segment, the segment being connected to the inner housing via spring elements. Due to the resilient arrangement of the segment, the gap between the central and compensating piston can be optimized.
An embodiment of the invention will now be explained in more detail with reference to the figures. The figures show schematically an embodiment of the invention.
- Figure 1
- a side view of a turbomachine according to the prior art,
- Figure 2
- a side view of a turbo machine according to the invention,
- Figure 3
- a detail of the arrangement according to the invention.
Shows a turbomachine 1 in a side view. The turbo machine can be a steam turbine. The invention is applicable to high-pressure, medium-pressure and low-pressure turbine sections.
The turbomachine 1 essentially comprises a rotatably mounted rotor 2 which can rotate about an axis of rotation 3. The rotor 2 comprises guide vanes (not shown in more detail). An inner housing 4 is arranged around the rotor 2. The inner housing 4 comprises guide vanes (not shown in detail). A flow channel 6 is formed between the rotor 2 and the inner housing 4, which, due to the profiled design of the guide and rotor blades, leads to a conversion of the thermal energy of a steam into rotational energy of the rotor 2. An outer housing 5 is arranged around the inner housing 4.
Live steam flows into the steam turbine 1 via an inflow connection (not shown in more detail) and is expanded in the flow channel 6. The expanded steam then flows into a steam space 7 which is arranged between the inner housing 4 and the outer housing 5. As in the exemplary embodiment according to the prior art, the steam flows between a thrust compensation piston 8 of the rotor 2 into the steam space 7. The steam forms so-called streaks 9, which show a more or less asymmetrical flow course. In FIG. 3, three strands 9 are shown by way of example. The strands 9 here comprise a hot steam which shows a different distribution, which can lead to one-sided heating of the inner housing 4, which is illustrated in FIG. 1 by the asymmetrical elliptical cross-sectional view of the inner housing 4. The distance between the thrust compensation piston 8 and the inner housing 4 to the left of the axis of rotation 3 is less than the distance between the thrust compensation piston 8 and the inner housing 4 to the right of the axis of rotation 3.
This shows an embodiment of the turbomachine according to the invention. An essential feature is that the labyrinth seal 12 has means 10 between the thrust compensation piston 8 and the inner housing 4, which means 10 are designed to deflect a vapor located in the labyrinth seal 12.
The means 10 are formed in the direction of the axis of rotation 3 and have the effect that a twist is avoided. Only two means 10 are provided with the reference numeral 10 in FIG.
The means 10 thus act as so-called twist breakers, which lead to a homogenization of the depression in the strands 9. This can be seen clearly in the. Five strands 9 are shown, which flow out of the labyrinth seal 12 almost symmetrically to the axis of rotation 3 and heat the inner housing 4 uniformly. In any case, no one-sided heating of the inner housing 4 will lead to a curvature, so that the radial clearances are smaller than the embodiment according to FIG.
The shows a detail of the labyrinth seal 12 with the means 10, which are designed as a twist breaker. The thrust compensation piston 8 comprises on its thrust compensation piston surface 11 a labyrinth seal 12 which is arranged by flow obstacles 13 both on the thrust compensation piston 8 and on an inner housing surface 14.
The means 10 can in this case be designed as a sheet metal which is essentially aligned in the direction of the axis of rotation. The means 10 can be arranged in the inner housing 4. In alternative embodiments, the means 10 can be arranged in a segment not shown in detail, the segment being connected to the inner housing 4 via spring elements not shown in detail.