EP2347101B1 - Gas turbine and corresponding gas or steam turbine plant - Google Patents

Description

The invention relates to a gas turbine having a substantially hollow conical or hollow cylindrical, extending along a machine axis vane carrier and a segmented in the circumferential and / or axial direction in ring segments, substantially hollow cone-shaped or hollow cylindrical outer wall of an annular hot gas path whose ring segments by means of a number are fastened by hooking elements on the inside of the guide blade carrier.

Gas turbines are used in many areas to drive generators or work machines. In this case, the energy content of a fuel is used to generate a rotational movement of a turbine shaft. For this purpose, the fuel is burned in a combustion chamber, compressed air being supplied by an air compressor. The working medium produced in the combustion chamber by the combustion of the fuel, under high pressure and at high temperature, is guided via a turbine unit arranged downstream of the combustion chamber, where it relaxes to perform work.

To generate the rotational movement of the turbine shaft, a number of rotor blades, which are usually combined into blade groups or rows of blades, are arranged thereon and drive the turbine shaft via a momentum transfer from the working medium. For guiding the flow of the working medium, guide vanes are also usually arranged between adjacent rotor blade rows and connected to the turbine housing, which are combined into rows of guide blades. These are attached to a usually hollow cylindrical or hollow cone-shaped vane carrier.

In the design of such gas turbines in addition to the achievable power usually a particularly high efficiency is a design target. An increase in the efficiency can be achieved for thermodynamic reasons basically by increasing the exit temperature, with which the working fluid flows from the combustion chamber and into the turbine unit. Temperatures of about 1200 ° C to 1500 ° C for such gas turbines are sought and achieved.

At such high temperatures of the working medium, however, exposed to this components and components are exposed to high thermal loads. Therefore, the hot gas channel is usually lined by so-called ring segments which form axial sections of the outer wall of the hot gas channel. These are usually fastened via hooking elements on the guide blade carrier, so that the entirety of the ring segments in the circumferential direction as well as the guide blade carrier form a hollow conical or hollow cylindrical structure.

The components of the gas turbine can deform by different thermal expansion in different operating conditions, which has a direct influence on the size of the radial gap between the blades and the outer wall of the hot gas channel. These radial gaps are differently dimensioned when starting and stopping the turbine than in regular operation. In the construction of the gas turbine components such as guide vane or outer wall are always to be dimensioned so that the radial gaps are kept sufficiently large to cause any damage to the gas turbine in any operating condition. However, a correspondingly comparatively generous design of the radial gaps leads to considerable losses in the efficiency.

To counter this problem, the JP 2005-042612 to design the guide vane carrier coolable, to design, whereby the thermally induced deformation should be avoided. After JP 54-081409 this problem should be solved with several gas sampling chambers, which leads to a uniform stiffness of the upper and lower housing part.

The invention is therefore based on the object to provide a gas turbine, which allows a particularly high efficiency while maintaining the greatest possible operational safety and life.

This object is achieved according to the invention in that the interlocking elements of at least one of the ring segments of the input gas turbine engine are geometrically adjusted such that in the non-operating state the outer wall delimiting the hot gas path has a substantially elliptical cross-sectional contour in a section perpendicular to the machine axis.

The invention is based on the consideration that a particularly high efficiency would be possible by reducing the radial gaps in regular operation, ie, for example, full load operation of the gas turbine. Until now, a comparatively large dimension of the radial gaps was required in particular because the turbine deforms differently in different operating states. In particular, an ovalization of the cylindrical or conically shaped components of the gas turbine occurs, which must be taken into account in the design of the radial gaps. In order to enable a reduction of the radial gaps in the design of the gas turbine, therefore, the ovalization in the operation of the gas turbine should be kept as low as possible. This should be achieved by a correspondingly adapted cross-sectional contour of the hollow cone-shaped or hollow cylindrical components of the gas turbine in the inoperative state, ie at cooled to room temperature gas turbine. This cross-sectional contour should be designed in such a way that the cross-sectional contour present at room temperature after installation of the gas turbine is then circular due to thermal deformations occurring in the operating state Cross-sectional contour leads. This can be achieved by the interlocking elements of at least one of the ring segments are geometrically adapted such that in the non-operating state in a section perpendicular to the machine axis, the outer wall defining the hot gas path has a substantially elliptical cross-sectional contour. The thermal expansions should therefore not, as in the prior art JP 2005-042612 and JP 54-081409 to be suppressed.

It is relatively easy to manufacture the ring segments described at the beginning, with which the hot gas path is lined outside the rotor blades, correspondingly. The ring segments form in the axial section of the blades in the circumferential direction of the outer wall of the hot gas path, which thus together form the rotor blades the closest lying hollow cone-shaped or hollow cylindrical component of the gas turbine. Therefore, the cross-section perpendicular to the machine axis of the ring segments forming the outer wall of the hot gas path has the elliptical cross-sectional contour described in the inoperative state.

The ring segments forming the outer wall of the hot gas path in the axial section of the rotor blades are usually hooked in the guide blade carrier via hooking elements. Since the vane support is a relatively solid component which has a comparatively large deformation during operation, the cross-sectional contour formed by all ring segments in the operating state is often determined by the attachment or clamping of the ring segments in the vane support and its deformation during operation. It is therefore not absolutely necessary to manufacture the cold contour of the external wall consisting of ring segments in elliptical form, since the deformation induced by the contact points on the interlocking elements is established anyway. The compensation of the ovalization of the guide vane carrier can therefore be achieved by advantageously only the individual hooking elements of the ring segments are adapted so that the outer wall of a substantially elliptical Has cross-sectional contour. Since these ring segments are exchangeable service parts, this makes it possible on the one hand to retrofit existing gas turbines, on the other hand to compensate for manufacturing errors in guide vanes and also a particularly simple adaptation to changing driving styles including other modified measures to reduce the radial gap.

In an advantageous embodiment, the length of the main and minor axes of the elliptical cross-sectional contour in each case selected such that the respective component has a substantially circular cross-sectional contour by its thermal deformation in the operating state in the production of the hollow cone-shaped or hollow cylindrical components of the gas turbine. This can be done, for example, by introducing an expected in operation by 90 degrees offset ovalization. The elliptical shape of these components is thus chosen so that the deformations are compensated in the operating state just so that the operation produces a circular cross-section and thus over the entire circumference of the gas turbine same radial gaps are present, d. h., The radial gaps have no variance over the circumference. As a result, even in the construction of the radial gaps can be sized accordingly narrow, which has a higher efficiency of the gas turbine result.

Advantageously, the interlocking elements are adapted in their radial length and / or arranged to change the radial position of the interlocking elements in a corresponding retaining groove of the guide blade carrier inserts. These then lie between the hooks of the hooking elements and the retaining groove and thus lead along the circumference to different radial positions of ring segments. De Facto can thus be provided either distributed along the circumference ring segments with different lengths radial entanglements in the vane support, or the Verhakungselemente the ring segments along a circumference are identical, in which case to change the radial Position of the ring segments along the circumference of different thickness supplements are used for the corresponding entanglements.

Due to the illustrated elliptical configuration of the hollow cone-shaped or hollow cylindrical components of the gas turbine in the inoperative state, a substantially circular shape can be achieved for the operating state, moreover, the present in the inoperative state elliptical shape can be considered in the design of the radial column and construction of the gas turbine on. This problem can be counteracted by a gas turbine equipped with the described counter oval manufactured components advantageously having a bearing device of the turbine shaft, which is designed such that the turbine shaft is displaceable along the turbine axis. As a result, in the cold operating state, the turbine shaft can be displaced in the direction of the hot gas flow, so that an enlargement of the radial gap occurs in the case of a hollow conical shape of the outer wall with enlargement of the radius in the direction of the hot gas flow in the cold inoperative state, and thus in the cold state (eg when starting the combustion process) Gas turbine), the remaining counter-ovalization represents no restriction for the achievable radial gap in the warm state. As a result, an even greater efficiency of the gas turbine can be achieved.

Advantageously, such a gas turbine is used in a gas and steam turbine plant.

The advantages achieved by the invention are, in particular, that a particularly high efficiency of the gas turbine is achieved by a reduction of the radial gaps by a targeted design of the hollow cone-shaped or hollow cylindrical components of a gas turbine such that they have a substantially elliptical cross-sectional contour in the inoperative state. By an elliptical production, in which the introduced in the cold state ovalization by 90 ° relative to the occurring during operation Ovalization is twisted, the previous elliptical deformation, for example, the outer wall of the annular hot gas channel or the inner wall of the vane support is reduced or avoided in the operating state. The homogenization of the radial gaps on the circumference reduces flow losses and thus improves the efficiency of the machine. In addition, the cold gaps in the new building can be reduced, since the amount of ovalization no longer has to be kept in the gap generation.

FIG 1

einen Halbschnitt durch eine Gasturbine,

FIG 2

einen Querschnitt durch den Leitschaufelträger einer Gasturbine nach dem Stand der Technik, und

FIG 3

einen Querschnitt durch den Leitschaufelträger einer Gasturbine mit eingebrachter Ellipsenform im Außerbetriebszustand.

The invention will be explained in more detail with reference to a drawing. Show:

FIG. 1

a half-section through a gas turbine,

FIG. 2

a cross-section through the guide vane support of a gas turbine according to the prior art, and

FIG. 3

a cross section through the vane support of a gas turbine with incorporated elliptical shape in the inoperative state.

Identical parts are provided with the same reference numerals in all figures.

The gas turbine 1 according to FIG. 1 has a compressor 2 for combustion air, a combustion chamber 4 and a turbine unit 6 for driving the compressor 2 and a generator, not shown, or a working machine. For this purpose, the turbine unit 6 and the compressor 2 are arranged on a common, also referred to as a turbine rotor turbine shaft 8, with which the generator or the working machine is connected, and which is rotatably mounted about its turbine axis 9. The running in the manner of an annular combustion chamber 4 is equipped with a number of burners 10 for the combustion of a liquid or gaseous fuel.

The turbine unit 6 has a number of rotatable blades 12 connected to the turbine shaft 8. The blades 12 are arranged in a ring on the turbine shaft 8 and thus form a number of blade rows. Furthermore, the turbine unit 6 comprises a number of stationary vanes 14, which are also attached in a donut-like manner to a vane support 16 of the turbine unit 6 to form rows of vanes. The blades 12 serve to drive the turbine shaft 8 by momentum transfer from the turbine unit 6 flowing through the working medium M. The vanes 14, however, serve to guide the flow of the working medium M between two seen in the flow direction of the working medium M consecutive blade rows or blade rings. A successive pair of a ring of vanes 14 or a row of vanes and a ring of blades 12 or a blade row is also referred to as a turbine stage.

Each vane 14 has a platform 18 which is arranged to fix the respective vane 14 to a vane support 16 of the turbine unit 6 as a wall element. The platform 18 is a thermally comparatively heavily loaded component which forms the outer boundary of a hot gas channel for the working medium M flowing through the turbine unit 6. Each blade 12 is attached to the turbine shaft 8 in an analogous manner via a platform 19, also referred to as a blade root.

Between the spaced-apart platforms 18 of the guide vanes 14 of two adjacent rows of stator blades ring segments 21 are arranged on a guide blade carrier 16 of the turbine unit 6 respectively. The inner surface of each ring segment 21 is also exposed to the hot, the turbine unit 6 flowing through the working medium M and therefore limits the outside of the annular hot gas path as the outer wall. In the radial direction is the outer wall from the outer end of the opposite blades 12 spaced by a radial gap. The ring segments 21 arranged between adjacent guide blade rows serve in particular as cover elements which protect the guide blade carrier 16 or other housing built-in components against thermal overstress by the hot working medium M flowing through the turbine 6.

The combustion chamber 4 is designed in the embodiment as a so-called annular combustion chamber, in which a plurality of circumferentially around the turbine shaft 8 arranged around burners 10 open into a common combustion chamber space. For this purpose, the combustion chamber 4 is configured in its entirety as an annular structure which is positioned around the turbine shaft 8 around.

2 and FIG. 3 now schematically show the guide vane 16 of the gas turbine 1 in a cross section perpendicular to the turbine axis 9 once left in the inoperative state, ie at cold gas turbine 1, and right in the operating state, ie at operating temperature. In the inoperative state, therefore, the guide vane carrier 16 has a material temperature corresponding to the ambient temperature of the gas turbine. The operating temperature, however, is much higher; beyond 100 ° C. The guide blade carrier 16 is composed of an upper segment 24 and a lower segment 26. The two segments 24, 26 are connected to one another via flanges 28 and each form a connecting joint 30 at their connection point.

Due to the high operating temperatures of the gas turbine 1 is in the operating condition - as right in the FIG. 2 4 illustrates a deformation of the prior art vane support 16 such that the distance between the peaks 32 of the respective upper and lower portions 24, 26 increases. The cross section of the guide blade carrier 16 thereby deforms into a vertical ellipse. A circular contour is shown for comparison in dashed line style.

This deformation can now be compensated by a deliberately introduced elliptical configuration of the cross section of the vane support 16 in the cold non-operating state, as in FIG. 3 shown. In the inoperative state, the distance between the apexes 32 of the upper and lower segments 24, 26 is shortened, so that the cross-section in the inoperative state replicates a horizontal ellipse, which results in FIG. 3 is shown on the left. Due to the thermally induced expansion and enlargement of the distance between the peaks 32 in the operating state, as shown on the right, then results in a substantially circular shape of the vane support 16, as in FIG. 3 shown on the right.

In order not to create any restrictions in the inoperative state due to the introduced ovalization with respect to the radial gaps, the turbine shaft 8 is displaceable along the turbine axis 9. In the cold state, that is, if there is an elliptical shape of the hot gas channel, then the turbine shaft 8 can be moved in the direction of the hot gas flow direction. As a result of the conical shape of the hot gas channel, this causes an enlargement of the radial gaps. Then, when in operation, a circular cross-section sets by thermal deformation, the turbine shaft 8 is displaced in the reverse direction to optimize the radial gap.

Alternatively, the ring segments 21 can be configured by a correspondingly introduced ovalization so that the hot gas channel receives a circular cross-section during operation. For this purpose, the Verhakungselemente for fixing the ring segments 21 on the guide blade carrier 16 may be different lengths, ie be different lengths for different circumferential positions, or inserts between the hook and holding the guide vane 16 are introduced, which influence the radial position of the respective ring segments 21 with the same length Verhakungselementen. The perpendicular to the machine axis cross-sectional contour of the Ring segments 21 formed radially outer outer wall of the annular hot gas channel is namely largely determined by the passed through the Verhakungselemente the ring segments deformation of the vane support 16. Accordingly, in 2 and FIG. 3 Instead of guide vanes 16 also be understood - then flangeless - the outer wall of the hot gas path of a gas turbine.

By such an elliptical shape of the vane support 16 or the outer wall of the ring segments of the hot gas channel of the gas turbine 1, the ovalization can be avoided in the operating state. As a result, in the design of the gas turbine 1, the radial gaps can be designed correspondingly smaller, resulting in a significantly higher overall efficiency of the gas turbine 1 without sacrificing operational safety.

Claims (5)

1. Gas turbine (1) having a stator blade support (16), which is essentially hollow-conical or hollow-cylindrical and extends along a machine axis, and having an outer wall, which is essentially hollow-conical or hollow-cylindrical and is segmented into annular segments (21) in the circumferential and/or axial direction, of an annular hot gas path, whose annular segments (21) are attached by means of a number of hook elements to the inside of the stator blade support (16)
   characterized in that
   the hook elements of at least one of the annular segments (21) are geometrically matched such that, when not in operation, the outer wall which bounds the hot gas path has an essentially elliptical cross-sectional contour in a section at right angles to the machine axis.
2. Gas turbine (1) according to Claim 1,
   wherein the lengths of the main and secondary axes of the elliptical cross-sectional contour are in each case chosen such that the outer wall has an essentially circular cross-sectional contour after the thermal deformation which occurs in the operating state.
3. Gas turbine (1) according to Claim 1 or 2,
   wherein the radial lengths of the hook elements are matched, and/or enclosures for different radial positions of the hook elements are arranged in an annular groove in the stator blade support (16).
4. Gas turbine (1) according to one of Claims 1 to 3, which comprises a turbine shaft (8) having a number of rotor blades (12), which are grouped to form rotor blade rows and are arranged circumferentially, and a bearing device for the turbine shaft, which is designed such that the turbine shaft (8) can be moved along the turbine axis (9).
5. Gas and steam turbine installation having a gas turbine (1) according to one of Claims 1 to 4.

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