EP2119878A1 - Steam turbine with partitioned inner casing - Google Patents

Abstract

The housing has an inner housing part (4a) made of high heat resistance material than another inner housing part (4b), where the inner housing parts are connected with each other by detachable connections (10). The former inner housing part is formed for feeding fresh steam and made of nickel-base-material. The latter inner housing part has a console on which the former inner housing part is mounted. The former inner housing part has a plug for fitting on the console. A sealing is arranged between the inner housing parts, and a medium i.e. projection, is formed on the console.

Description

The invention relates to an inner casing for a steam turbine, wherein the inner casing comprises a first inner casing part and a second inner casing part, wherein the first inner casing part consists of a higher heat-resistant material than the second inner casing part.

The efficiency of a turbomachine, in particular a steam turbine, depends u. a. from the temperature of the incoming fresh steam. The higher the temperature of the live steam, the higher the expected efficiency. Currently there are efforts to increase the steam temperature of the live steam, which is currently at about 620 ° C, to temperatures of up to 700 ° C and above 700 ° C. Such high temperatures lead to high thermal loads of individual components such. B. the inner housing. At the aforementioned high temperatures, either suitable cooling options must be used or suitable materials used. Materials based on the so-called nickel-based materials are suitable for use in steam turbines, which can be exposed to temperatures above 700 ° C.

However, the costs of nickel-based materials are comparatively high. Therefore, the weight content of nickel-based components should be kept as low as possible. In addition, for manufacturing reasons, the maximum weight of the housing parts of the inner housing should not be too high.

Inner housings are known, which are made of a first material and a second material, wherein the inner housing has a weld, wherein the first material is welded together with the second material.

The invention has therefore set itself the task of specifying an inner casing for a steam turbine, which is suitable for high temperatures and high powers and has comparatively small large components.

This object is achieved by an inner housing for a steam turbine, wherein the inner housing comprises a first inner housing part and a second inner housing part, wherein the first inner housing part of a higher heat resistant material than the second inner housing part, wherein the first inner housing part and the second inner housing part via a releasable connection with each other connected is.

This object is also achieved by an inner housing according to the preamble of claim 1, wherein the first inner housing part and the second inner housing part is connected to each other via a heat-movable connection.

The invention is therefore the way, instead of a complete, made of a material inner housing to use two inner housing parts, which are connected to each other via a detachable connection. The first inner housing part is in this case formed of a higher heat-resistant material than the second inner housing part. The fresh steam entering the steam turbine can therefore be led to the first inner housing part, since the high-temperature resistant material can withstand the thermal conditions.

Due to the different thermal expansions of the first inner housing part and the second inner housing part they are connected to each other heat-movable. One of the advantages is that movably suspended components must withstand lower stresses.

By a detachable connection of the first inner housing part with the second inner housing part a better transport and mounting option is given. The first inner housing part and the second inner housing part can each be separated transport for themselves, which leads to an advantage, since the respective inner housing parts taken by themselves have a comparatively high weight. A single component comprising the first inner housing part and the second inner housing part would have a comparatively high weight, which adversely affects the transport and assembly.

In the dependent claims advantageous developments are given.

In an advantageous development, the first inner housing part is made of a nickel-based material. Nickel-based material is suitable for exposure to high-temperature live steam. Therefore, it is advantageous to manufacture only the region of the inner housing with a nickel-based material, which is thermally heavily loaded.

The inner housing parts are connected to each other axially via a kind of tongue and groove. As a result, an axial fixation of the inner housing parts to each other is ensured. In addition, an axial force transmission, for. B. by shear forces from the internal pressure, guaranteed. Furthermore, a sealing of the inner housing parts is possible, with a radial thermal mobility is ensured. The support and guide elements should be designed so that they do not hinder the thermal expansion and center the housing to each other and can transfer the forces of the weight and torque.

In an advantageous development, the second inner housing part has a console on which the first inner housing part is mounted to bear. The console can be formed here as a projection having a support surface on which the first inner housing part can be supported. This is a comparatively simple design solution to produce a detachable connection.

Advantageously, the first inner housing part on a claw, which is designed to be placed on the console. The first inner housing part and the second inner housing part are thus detachably connected to one another via a bracket and claw pair. So that a displacement of the first inner housing part relative to the second inner housing part is avoided, the console has means which prevent displacement. These means are formed as projections on the console, wherein the claw bears against the projection. A displacement of the second inner housing part relative to the first inner housing part is prevented because the claw hits against the agent. The formation of a projection on the console is a comparatively simple design solution with which a shift can be prevented.

In a further advantageous embodiment, a seal between the first inner housing part and the second inner housing part is provided. Since the inner housing usually undergoes a start-up and shut-down cycle in which the inner housing is alternately heated and cooled, movements of the first inner housing part relative to the second inner housing part due to thermal expansion are possible. Such thermal expansions could lead to leaks in the connection between the first inner housing part and the second inner housing part. By means of a seal between the first inner housing part and the second inner housing part is therefore avoided that an undesirable leakage steam between the first inner housing part and the second inner housing part flows out.

In an advantageous development, a third inner housing part is provided, wherein the first inner housing part between the second inner housing part and the third inner housing part is arranged. In particular, in medium-pressure turbine sections, the inner housing is formed such that the flow medium flows in two directions along, wherein the directions are opposite to each other. In general, such an arrangement is referred to as a double-flow steam turbine.

The first inner housing part accordingly forms the central part of the inner housing, which is acted upon by the live steam. The second inner housing part and the third inner housing part are virtually releasably connected to the left and right of the inner housing part. The releasable connection between the first and second inner housing part can be made identical to the detachable connection between the first and third inner housing part. In particular, the third inner housing part has a second bracket, on which the first inner housing part is mounted to bear.

The first inner housing part is in this case made of a nickel-based material.

The invention will be explained in more detail with reference to an embodiment. Components with the same reference numerals have the same meaning in the various figures.

Show it:

FIG. 1

a cross-sectional view of a medium-pressure turbine section;

FIG. 2

a cross-sectional view of a heat-movable connection;

FIG. 3

a schematic representation of an inner housing.

The FIG. 1 shows a cross-sectional view of a medium-pressure turbine part 1. The medium-pressure turbine part 1 comprises a substantially rotatable about a rotation axis 2 rotatably mounted rotor 3. The rotor 3 has blades not shown in detail. An inner housing 4a, 4b, 4c is arranged around the rotor 3, the inner housing 4 having a first inner housing part 4a, a second inner housing part 4b and a third inner housing part 4c. The first inner housing part 4a, the second inner housing part 4b and the third inner housing part 4c have guide vanes (not shown in more detail) which, together with the moving blades, form a flow channel 5 through which a flow medium is passed. The medium-pressure turbine section 1 further comprises an outer housing 6 arranged around the rotor 3 and the inner housing 4. Fresh steam initially flows through a live steam connection 7 into a live steam zone 7. Subsequently, the live steam moves along a first flow direction 8a and a second flow direction 8b in the flow channel 5. In the flow channel 5, the steam is released and cools down. After flowing through the flow channel 5, the expanded and cooled steam flows out of the intermediate-pressure turbine 1 via an exhaust steam region 9.

The fresh steam flowing into the live steam region 7 can have temperatures of more than 620 ° C., in particular up to more than 720 ° C. The first inner housing part 4a is made of a nickel-based material, wherein the second inner housing part 4b and the third inner housing part 4c is made of a less high-temperature resistant material.

The first inner housing part 4a, the second inner housing part 4b and the third inner housing part 4c are formed substantially rotationally symmetrical about the axis of rotation 2 and each have an upper and a lower housing part. The outer housing 6 also includes an upper and a lower housing part. The first inner housing part 4a is mounted on support brackets, which are not shown in detail and center guides in the outer housing 6.
Likewise, the first inner housing part 4 a could also be held via the second 4 b and third inner housing part 4 c by means of supports and centerings, when the second inner housing 4 b and the third inner housing 4 c are in turn held by supports and center guides to the outer housing 6. In this case, an axial fixing on the first inner housing part 4a and second inner housing part 4b is provided. The first inner housing part 4a, the second inner housing part 4b and the third inner housing part 4c are axially connected to each other.

The first inner housing part 4a is connected via a heat-movable connection 10 both to the second inner housing part 4b and to the third inner housing part 4c.

In an alternative embodiment, not shown, the first inner housing part 4a is mounted on support brackets and center guides, not shown, on the inner housings 4b and 4c. The second inner housing part 4b and the third inner housing part 4c are in turn in the outer housing 6 via support brackets, which are not shown in detail, stored and guided with center guides in the outer housing 6.

An essential aspect is that the inner housing parts 4a, 4b and 4c are formed so as to be heat-movable with respect to each other.
In the heat-moving connection, a seal takes place at the same time. The sealing is done essentially by the metallic laying, since the forces that are transmitted to such compounds are very large.

The detachable connection 10 in this case has a bracket 11 which is arranged on the second inner housing part 4b and on the third inner housing part 4c, wherein the first inner housing part 4a is supported supportingly on the console. For this purpose, the first inner housing part 4a on a claw 12, which is designed to be placed on the console 11. The bracket 11 has means 13 for preventing displacement of the first inner housing part 4a relative to the second inner housing part 4b. The means 13 is formed as a projection on the bracket 11, wherein the claw 12 bears against this projection.

In the FIG. 2 the detachable connection 10 is shown in more detail. The releasable connection represents the connection of the first housing part 4a with the second housing part 4b. The means 13 prevent a displacement of the claw 12 in the console 11. This results in a heat-movable displacement of the first inner housing 4a with respect to the first inner housing 4b effectively avoided.

In the FIG. 3 is a schematic representation of the inner housing 4 can be seen. In this case, the first inner housing part 4a is connected to the second inner housing part 4b or the third inner housing part 4c via detachable connections 10, which are realized by brackets 11 and claws 12.

The first inner housing part 4 a can be effectively protected from disturbing steam temperatures in the exhaust-steam region 9 by means of a jacket 14, which is manufactured from steel sheets. By separating the inner housing 4 into a first inner housing part 4a, a second inner housing part 4b and a third inner housing part 4c, a significant reduction of the piece weight of the individual inner housing parts is possible. For this purpose housing deformations can be effectively influenced by the control of the cooling steam temperature.

Simplified shown, there are basically two options for the support of the inner housing parts 4a, 4b and 4c to each other.
On the one hand, the first inner housing part 4a is supported and centered via the second inner housing part 4b and the third 4c, wherein the second inner housing part 4b and the third inner housing part 4c in turn are mounted in the outer housing 6 and centered.
On the other hand, the first inner housing part 4a is mounted directly in the outer housing 6 and centered. The second inner housing part 4b and the third inner housing part 4c are each fixed on the connection side to the first inner housing part 4a to the first inner housing part 4a by means of supports and center guides and again additionally on the respective downstream side in the outer housing 6 by means of supports and center guides.

Claims (14)

Inner housing (4) for a steam turbine,
wherein the inner housing (4) comprises a first inner housing part (4a) and a second inner housing part (4b),
wherein the first inner housing part (4a) is made of a higher heat resistant material than the second inner housing part (4b),
characterized in that
the first inner housing part (4a) and the second inner housing part (4b) are connected to one another via a detachable connection (10). Inner housing (4) according to claim 1,
wherein the first inner housing part (4a) is designed to flow with live steam and is made of a highly heat-resistant material than the second inner housing part (4b). Inner housing (4) according to claim 2,
wherein the first inner housing part (4a) is made of a nickel-based material. Inner housing (4) according to one of the preceding claims,
wherein the second inner housing part (4b) has a bracket (11) on which the first inner housing part (4a) is mounted to bear. Inner housing (4) according to claim 4,
wherein the first inner housing part (4a) has a claw (12) which is designed to be placed on the bracket (11). Inner housing (4) according to claim 4 or 5,
wherein the bracket (11) has means (13) for preventing displacement of the first inner housing part (4a) relative to the second inner housing part (4b). Inner housing (4) according to claim 6,
wherein the means (13) formed as a projection on the bracket (11) and the claw (12) abuts the projection. Inner housing (4) according to one of the preceding claims,
wherein a seal (10) between the first inner housing part (4a) and the second inner housing part (4b) is arranged. Inner housing (4) according to one of the preceding claims,
wherein a third inner housing part (4c) is provided,
wherein the first inner housing part (4a) is arranged between the second inner housing part (4b) and the third inner housing part (4c). Inner housing (4) according to claim 5,
wherein the third inner housing part (4c) has a second bracket (11) on which the first inner housing part (4a) is mounted to bear. Inner housing (4) according to claim 10,
wherein the first inner housing part (4a) has a second claw (12), which is designed to be placed on the second bracket (11). Inner housing (4) according to claim 10 or 11,
wherein the second bracket (11) has a second means (13) for preventing displacement of the first inner housing part (4a) relative to the third inner housing part (4c). Inner housing (4) according to claim 12,
wherein the second means (13) formed as a second projection on the second bracket (11) and the second claw (12) abuts the second projection. Inner housing (4) according to one of the preceding claims,
wherein the inner housing (4) is designed for installation in a medium-pressure turbine section (1).

Images