EP1163430B1 - Covering element and arrangement with a covering element and a support structure - Google Patents

Abstract

The invention relates to a covering element (2) for protecting components, especially components in a gas turbine (1), in a machine that is subjected to high thermal stress. The covering element (2) is provided with a wall (8) with a hot side (10) which can be exposed to a hot medium (M) and a cold side (12) which is opposite the hot side (10). The cold side (12) is provided with a cooling surface (14) that can be subjected to a coolant (K). Holding elements (28) are provided on the cold side (12). The invention also relates to an arrangement with a covering element (2) and with a support structure (34). The arrangement is tolerant with respect to thermal expansion.

Description

The invention relates to a cover element for protecting components in a thermally highly stressed machine, in particular of components in a gas turbine. The invention relates further an arrangement with a cover and with a supporting structure.

Components in a thermally highly stressed machine during regular operation of this machine at high temperatures exposed. In a thermal machine, especially in a gas turbine, are heated by a hot medium, e.g. on Hot gas, primarily the surfaces delimiting the hot medium and the associated components are very thermally stressed. As a result of heat transfer through these confining surfaces, such as in the form of heat conduction or Heat radiation occur, are also components, which are not directly exposed to the hot medium and often built into the machine housing, high thermal Subjected to loads. So they fulfill the hot Components exposed to medium have two functions: Inclusion the hot medium and protecting others, possibly less heat-resistant components from overheating or thermal Destruction. As a result, there are high requirements especially in terms of material properties as well as the constructive Design and assembly of these thermally highly stressed Components. In addition, there are often requirements to consider the coolability of such components.

For example, loads occur during operation of a gas turbine from mechanical stress (e.g. due to internal pressure, Centrifugal force, external forces and moments) and as a result of thermal stresses due to the prevented thermal expansion of Components with temperature differences result. While in stationary operation the temperature differences and thus thermal stresses are generally small compared to mechanical ones Stress, are in transient operation with load changes as well as start-up and shutdown processes the transient Thermal stresses mostly determining because of changes in load are necessarily associated with temperature changes. At high Working temperatures and large temperature differences between the individual load conditions therefore occur Thermal expansions, especially the housing and the rotors affect.

A cover element according to the preamble of claim 1 shows the US 5,127,793.

Furthermore, an axial gas turbine is described in US Pat. No. 3,892,497 described with an inner and an outer housing insert. In the gas turbine there are guide vanes and rotor blades arranged along a turbine axis. A guide vane each has a platform (vane root), which for fastening the guide vane to the inner housing insert serves. Between each two adjacent and axially to each other spaced guide vanes is a guide ring on inner housing insert arranged that the guide ring on the corresponding platforms of the guide vanes are adjacent. Platforms and guide rings are from the inside through the inside Housing insert held and with this via support elements connected. Each support element is fixed to the inside Housing insert through a combination of locking plate with one engaging in the inner housing insert Screw connected. The platforms of the guide vanes and the Guide rings have grooves in which the support element engages. A support element either engages in a groove a platform or in a guide ring, engaging in the axial direction at the edge of the platform or guide ring is made. This attachment lets in To some extent, a relative thermal in the axial direction Expansion and contraction between adjacent components and also enables simplified assembly and maintenance of the gas turbine. From the patent specification also shows a fastening for a guide ring, at the one guided radially through the inner housing insert Locking screw directly with a rigid connection the guide ring is made. The locking screw is fixed here the guide ring locally at a point between its axial edges. This configuration leads to thermal Stress on the guide ring to considerable local thermal stresses in the axial and especially in the radial direction, since thermal expansion is only possible to a very limited extent.

The invention has for its object a thermally highly resilient and at the same time, the component that can be cooled as efficiently as possible specify. The component should be used for high working temperatures and large temperature differences be suitable between different load conditions. Another The object of the invention is an arrangement with a Specify component and with a support structure, in particular a thermal expansion tolerant fastening of the component in of the supporting structure.

According to the invention, the first object is achieved by a cover member that has a longitudinal axis and a transverse axis comprising a wall with a hot medium removable hot side and one opposite the hot side Cooling side, which can be acted upon with a coolant Has cooling surface, and further comprising one along the longitudinal axis of the first bearing area adjacent to the wall with a first contact surface and one along the Longitudinal axis opposite the first support area second Contact area with a second contact surface, and further comprising one adjacent to the wall along the transverse axis first edge area and one along the transverse axis first edge area opposite second edge area, a holding element being provided on the cooling side, arranged between the first and the second support area is.

The invention is based on the consideration that a component in a thermal machine, which is a hot medium, e.g. exposed to hot gas or steam due to temperature the medium is thermally very heavily loaded. With these high temperatures or large temperature changes heat-related deformations, especially thermal expansion, the design and assembly of such components are to be considered. With the invention new possibility of thermal expansion tolerant design and arrangement of components in thermally highly stressed machines created.

An above cover element forms with it the hot medium exposed hot side a defined limitation of the hot Medium, e.g. of the hot gas in the combustion chamber or in the flow channel a gas turbine. The cover element also serves as a thermally highly resilient component to protect other possibly less heat-resistant components that are not directly exposed to the hot medium and in Housing of the thermal machine, in particular the gas turbine, are arranged. The cover element prevents this Function the thermal overload or even destruction of these components. On the cooling side of the cover is a Bracket provided between the first and the second support area is arranged. The bracket element is an integral part of the cover element and has the task between the first and second support areas for additional Stop worrying. The cover element is over the mounting element is held from the cooling side in such a way that in particular forces directed normal to the wall, for example due to mechanical and / or thermal stress the wall, absorbed efficiently and if necessary also can be transferred. At the same time can have very good cooling properties of the cover element can be guaranteed. This is realized in that the first and the second support area adjoin the wall along the longitudinal axis. Thereby is the side of the hot medium opposite Wall practically completely available as a cooling surface. With this design, the cooling surface is even with a coolant, e.g. Cooling air, acted upon, creating a very homogeneous cooling is made possible. This also affects particularly advantageous on the use of coolant, since the Cooling surface is designed as a coherent surface and thereby the coolant, if it is at one point of the Cooling side is supplied to all areas of the cooling surface can reach. Additional coolant feeds or coolant feedthroughs so there is no need for anything, especially in Is very advantageous in terms of manufacturing costs. The good cooling properties of the cover element also have an effect particularly favorable to the temperature distribution within the Wall of the cover element. As a result, temperature gradients occur essentially only normal to the cooling surface, i.e. from the hot side towards the cooling side. Thermal stresses along the longitudinal or transverse axis of the cover element, that could possibly induce cracks thereby largely avoided. Also with regard to the mechanical The proposed cover element proves to be stable as very beneficial. This primarily affects the Forces caused by possible pressure differences between the hot side and the cooling side of the cover element prevail can occur. Both the mechanical stress as well the thermal load of the cover element described above lead to a deformation of the wall, which is usually as a deflection of the wall towards the hot side. This effect is defined by the invention Dimension limited.

Another mounting element is preferably on the cooling surface, on the first or on the second edge area arranged. Another mounting element is the Possibility created, the cover element at another point to give additional support from the cooling side of the wall. The total load due to mechanical and / or thermal induced forces normal to the wall are thereby distributed on multiple mounting brackets, reducing the load correspondingly lower for each mounting element. Possible Deflection of the wall in the direction of the hot side as a result these forces are either further restricted or can by appropriate arrangement of the support members to be limited to a predetermined level. Furthermore remain the good cooling properties of the cover consist of the further mounting element, i.e. especially the formation of a coherent cooling surface on the Cool side. There are different combinations of two mounting elements realizable with respect to a given maximum deformation of the wall to the same desired Result. This gives you a certain freedom with regard to the arrangement of the mounting elements.

The mounting element preferably has a mounting contact surface on. The mounting element also preferably has a recess, in particular a groove, for engaging in a Support structure. This configuration is about Bracket, in combination with the first and second Support area as well as with a support structure, a thermal expansion tolerant Arrangement with the cover and with a Support structure possible. The manufacture of the bracket support surface as a partial area of the recess, in particular the groove in the mounting element is technically simple executable. The recess could be produced, for example by milling a groove or, in the case of a casting, by undermining by means of a simple core at Cast. The bracket support surface serves the Forces due to thermal and / or mechanical stress of the cover element and effectively on a support structure transferred to. Through the bracket support surface the sometimes considerable forces are not transmitted selectively, but spread over an area. Given thermal or mechanical stress can be the stress per surface, by appropriate dimensioning of the support surface on the material properties of the Cover element adapted dimension, limited.

The wall preferably has a wall thickness of between approximately 1.0 mm to 5.0 mm, in particular between about 1.5 mm to 3.0 mm, on. The wall is therefore opposite the first and the second contact area or the first or second edge area the cover element is comparatively thin. Depending on the application, the temperature difference during operation between the hot side loaded with the hot medium and the cooling side of the wall to which the coolant is applied be very big. For example, when using the cover in a gas turbine temperature differences between the hot gas and the coolant, especially the compressor cooling air extracted from the gas turbine, up to 800 ° C occur. Therefore, it is crucial to the wall as thin as possible so that the temperature gradient between Hot side and cooling side of the wall is as large as possible and the heat very efficiently with the lowest possible use of coolant can be dissipated. Efficient heat dissipation takes place mainly through the coolant. A small part of the Heat flow that flows into the wall from the hot side also along the longitudinal axis and the transverse axis in the first / second Support area and the first / second edge area of the cover element are derived because these areas, because of their larger cross-section compared to the wall, represent an additional heat sink.

The cooling surface preferably has a support structure for elevation of stiffness and thermal conductivity. The increase the rigidity of the cover element by the support structure has a very beneficial effect on the cooling surface on preventing deformations, especially deformations and deflections of the wall towards the hot side the Wall. Furthermore, this support structure causes Enlargement of the effective cooling surface, which leads to a Increases cooling efficiency. In addition to the enlargement The effective cooling surface is provided by the support structure an improved mixing of coolant with different Temperature in the immediate vicinity of the cooling surface. As a result, the temperature on the cooling surface increases on average off, and the temperature gradient and accordingly the heat transfer through the coolant is increased. In addition, due to the enlarged cross section opposite the wall the support structure along the support structure, the thermal conductivity slightly increased.

The support structure is preferably by at least one Longitudinal rib running along the long axis on the cooling surface. The support structure also preferably has a further longitudinal rib on the along the longitudinal axis on the Cooling surface is executed. The execution of the support structure in the form of one or more longitudinal ribs is a manufacturing technology very cheap solution, for example at a casting is easy and inexpensive to implement. In terms of improved thermal conductivity this configuration to heat dissipation through the Longitudinal ribs in the direction of the first and second contact area of the cover element. At the same time, the longitudinal ribs increase the rigidity of the component, which in turn is advantageous in Regarding possible deformations, especially deflections the wall from the cooling side to the hot side, at thermal or mechanical stress.

At least two are preferably in the direction of the transverse axis spaced longitudinal ribs connected to a support member. Due to this design, the mounting element understood as part of the support structure, so to speak become. This version serves to increase the rigidity and the increase in thermal conductivity, but above all that mechanical and thermal stability of the cover element at high temperature and / or pressure loads. Advantageous is again the simple implementation in terms of production technology this version.

The number and arrangement of the mounting elements are preferred determined by a predetermined thermal deflection of the wall. The predefined thermal is more preferably Deflection 0.1 mm to 1.0 mm, in particular 0.3 mm to 0.7 mm. The resulting thermal deflection depends on it from the temperature load and / or pressure load the cover element and its material properties and the constructive design, mainly with regard to the Number and arrangement of the support elements. At a typical temperature difference between hot side and cooling side of the cover element of approximately 800 ° C, as for example occurs in a stationary gas turbine the thermal deflection limits given above as meaningful values. In a concrete application a suitable configuration through computer-aided optimization the competing requirements between the deflection the wall on the one hand, and the number associated with it and arrangement of the mounting elements on the cooling surface, and an acceptable limitation on the effective cooling surface through the mounting elements on the other hand his. The proposed concept offers in terms to adapt to a specific task a very great flexibility.

At least two mounting elements are preferably in relation to one another spaced along the transverse axis. More preferred are at least two support elements to each other spaced along the longitudinal axis. With cover elements, which are dimensioned such that they are predominantly extend along the longitudinal axis or along the transverse axis, there are several along the preferred axis Bracket elements provided. This version is to the Symmetry properties of the cover element well adapted and comes at a given thermal deflection Wall with the smallest possible number of support elements out. In the case of cover elements that extend both along a Longitudinal axis and a transverse axis extend significantly, are preferably mounting elements in both dimensions arranged to achieve the desired effect. Of The advantage here is that the mounting elements are spaced apart are arranged and thus the cooling surface in all Embodiments always a coherent surface remains. This allows the cooling air from one place on the Cooling surface to another location on the cooling surface flow unhindered, and additional coolant supplies or coolant feedthroughs are not required.

The task based on an arrangement is invented solved by an arrangement with a cover according to one of the above and with a support structure that a longitudinal axis, a transverse axis and one along the longitudinal axis arranged first receiving area with a first Receiving surface and an opposite along the longitudinal axis second receiving area with a second receiving surface and has a support member with wing, the first receiving area to the first contact area and the adjoin the second receiving area to the second contact area and the support element and the support element overlap, wherein the bracket support surface and the wing face each other.

Are preferably without thermal stress, especially at Room temperature, the mounting surface and the wing spaced from each other by a gap. The cover element is usually in the support structure at room temperature used. The fact that the first recording area the first contact area and the second receiving area border the second support area, the cover already held in the supporting structure. The spacing of the Bracket support surface of the bracket member and the wing of the support element through a gap proves to be very cheap in terms of mounting the cover in the supporting structure. When operating a thermal machine, especially a gas turbine, i.e. under high thermal and mechanical stress, has the wall of the cover the tendency to bend towards the hot side. This will make the bracket support surface and the wing to cover and the forces due to thermal Loads are absorbed effectively. The one at room temperature selected distance between mounting surface and Wing determines which thermal load the bracket support surface and the wing for Cover and thus over the resulting thermal Deflection of the wall. In a thermally highly stressed state in this way the cover element is fixed in the supporting structure held, the thermal deflection of the wall in Direction of the hot side can be specified, in particular to a maximum Value can be limited.

Preferably one is between a receiving area and the adjoining support area formed configuration as Fixed bearing and the other configuration executed as a floating bearing. This version proves to be particularly advantageous since the arrangement with a cover and with a Support structure generally a mechanically highly overdetermined System. This system exhibits a number of Bearing configurations based on the receiving and adjacent Support areas as well as beyond that overlapping support elements and support elements are formed become. The version with a fixed bearing and a floating bearing ensures easy installation of the cover element in the Support structure in the thermally unloaded state. moreover is a thermal expansion along the cover the longitudinal axis. The thermal expansion takes place when the temperature rises from the fixed bearing towards the floating bearing out. The fixed bearing configuration is designed so that even with a slight rise in temperature compared to Room temperature and the corresponding recording area adjacent contact area come into contact with each other. The Floating bearing, however, is dimensioned so that even at very high Temperatures as they occur in the operation of a gas turbine can, the cover element along the longitudinal axis can still expand. In particular, the result Advantages of simple assembly and thermal expansion tolerances Arrangement of the cover element in a support structure. It are thermally induced deformations, especially thermal expansions, is taken into account, and at the same time at high temperatures the cover over the bracket elements firmly in the supporting structure held.

The fixed bearing preferably has a tolerance of between approximately 0.2 mm to 0.5 mm. More preferably, the floating bearing has a tolerance between about 4.0 mm to 10.0 mm.

The cover element and the support structure are preferably in a thermal machine, especially in a gas turbine, arranged. The thermal expansion tolerant fastening concept lends itself particularly well to a platform for fixation a gas turbine blade, with a guide ring in one Gas turbine, at a head platform of a guide vane Gas turbine or with a heat shield element in the combustion chamber a gas turbine. A distinction is made with a gas turbine Guide vanes and blades, each radial on rims are arranged to the axis of rotation of the gas turbine. A The guide vane has a platform which is used for fixation the guide vane on the inner turbine housing, in particular on Leitgittersegment is arranged. A blade is on the turbine rotor arranged along the axis of rotation attached via a platform. A guide ring is as a wall element in a gas turbine between the platforms of two axially spaced successive guide vanes arranged, The outer surface of the guide ring is that hot medium, especially the hot gas, exposed and in radial direction from the outer ends of the rotating blades spaced by a gap. In addition to the applications Further configurations of the cover element are in a gas turbine possible, for example as a wall element in ovens, in combustion chambers or in containers that can be filled with hot media.

FIG 1

einen Halbschnitt durch eine Gasturbine mit Verdichter, Brennkammer und Turbine,

FIG 2

einen Längsschnitt durch einen Ausschnitt einer Turbine,

FIG 3

eine perspektivische Darstellung eines Führungsrings einer Gasturbine,

FIG 4

eine Draufsicht auf einen Führungsring einer Gasturbine mit Kühloberfläche und Halterungselementen,

FIG 5

eine Ansicht des in Figur 4 gezeigten Führungsrings entlang der Schnittlinie VI-VI,

FIG 6

ein weiteres Ausführungsbeispiel (Draufsicht) eines Führungsrings einer Gasturbine mit Kühloberfläche und Halterungselementen,

FIG 7

eine Ansicht des in Figur 6 dargestellten Führungsrings entlang der Schnittlinie VII-VII,

FIG 8

einen Längsschnitt einer Anordnung eines Führungsrings im Leitgittersegment einer Gasturbine ohne thermische Belastung (bei Raumtemperatur),

FIG 9

einen Längsschnitt einer Anordnung eines Führungsrings im Leitgittersegment einer Gasturbine bei thermischer Belastung.

The invention is explained in more detail by way of example below with reference to some exemplary embodiments shown in the drawing. Some of them show schematically and simplified:

FIG. 1

a half-section through a gas turbine with compressor, combustion chamber and turbine,

FIG 2

a longitudinal section through a section of a turbine,

FIG 3

1 shows a perspective illustration of a guide ring of a gas turbine,

FIG 4

a plan view of a guide ring of a gas turbine with a cooling surface and mounting elements,

FIG 5

4 shows a view of the guide ring shown in FIG. 4 along the section line VI-VI,

FIG 6

another embodiment (top view) of a guide ring of a gas turbine with cooling surface and mounting elements,

FIG 7

6 shows a view of the guide ring shown in FIG. 6 along the section line VII-VII,

FIG 8

a longitudinal section of an arrangement of a guide ring in the guide vane segment of a gas turbine without thermal stress (at room temperature),

FIG 9

a longitudinal section of an arrangement of a guide ring in the guide vane segment of a gas turbine under thermal load.

The same reference numerals have in the individual figures same meaning.

FIG. 1 shows a half section through a gas turbine 1. The gas turbine 1 has a compressor 3 for combustion air, a combustion chamber 5 with burners 7 for one liquid or gaseous fuel with inside the Combustion chamber 5 arranged on the wall, not shown in Figure 1 Heat shield elements and a turbine 9 for driving of the compressor 3 and one not shown in FIG. 1 Generator on. There are fixed guide vanes in the turbine 9 11 and rotatable blades 13 on each themselves radially extending wreaths, not shown in half section arranged along the axis of rotation 21 of the gas turbine 1. In this case, one that follows one another along the axis of rotation 21 becomes Pair from a ring of guide vanes 11 (guide vane ring) and a ring of blades 13 (blade ring) referred to as the turbine stage. Each vane 11 has a platform 17 which is used to fix the relevant Guide vane 11 on the inner turbine housing 29 as Wall element is arranged. At the same time, this platform 17 a thermally highly stressed component, which the outer boundary of a hot medium M, in particular the Hot gas channel in the turbine 9, forms. The blade 13 is on the along the axis of rotation 21 of the gas turbine 1st arranged turbine rotor 19 via a corresponding platform 17 attached. A guide ring 15 is a cover element in a gas turbine 1 between the platforms 17 two axially spaced adjacent vanes 11 on the wall arranged. The outer surface 31 of the guide ring 15 is exposed to the hot medium M, in particular the hot gas, and in the radial direction from the outer end 27 of the blade 13 spaced apart by a gap. The one between neighboring Guide vane rings arranged guide rings 15 serve as cover elements that protect against thermal overload from built-in parts through the heat transfer protects the flowing hot medium M. In operation of the gas turbine 1 fresh air L is sucked in from the environment. The Air L is compressed in the compressor 3 and thereby simultaneously preheated. In the combustion chamber 5, the air L with the brought together liquid or gaseous fuel and burned. A part of the compressor 3 previously removed Air L serves as cooling air K for cooling the turbine stages, where e.g. the first turbine stage with a turbine inlet temperature from about 750 ° C to 1200 ° C becomes. Relaxation and cooling take place in the turbine 9 the hot medium M, in particular the hot gas, which flows through the turbine stages.

FIG. 2 shows a longitudinal section through in somewhat more detail a section of the turbine 9 shown in Figure 1 are guide vanes 11 and blades 3 on top of each other subsequently arranged along the axis of rotation 21 of the turbine 9. The guide vanes 11 each have a platform 17 which, for fixing the guide vane 11 on, in FIG. 2 only incompletely shown, inner turbine housing 29 as Wall element is arranged. The inner turbine housing 29 has a radially arranged guide vane segment 25, in a support structure 34 in the direction of the axis of rotation 21 is formed. The support structure 29 takes the platforms 17th the guide vanes 11 and in this way fixes the Guide blades 11. The blades 13 are along the the axis of rotation 21 arranged turbine rotor 19 each attached via a platform 17. Guide rings 15 are as Cover elements 2 in the turbine 9 between the platforms 17 two axially spaced consecutive vanes 11 arranged. The outer surface 31 of a cover member 2, in particular a guide ring 15, is called that Medium M, especially the hot gas, exposed and in radial Direction from the outer ends 27 of the blades 13 spaced by a gap 23. The outer surface 31 forms the hot side 10 of the cover element 2. The in the figure 2 shown support structure 34 of the guide vane segment 25 is designed so that the guide vanes 11 for several Records turbine stages. Between two along the axis of rotation 21 of the turbine 9 successive guide vanes 11 is the guide vane segment 25 with cover elements 2, which each represent a guide ring 15 which in the Support structure 34 is arranged, before thermal overload through the heat transfer from the flowing hot Medium M, especially the hot gas, is effectively protected. The guide rings 15 are in the support structure 34 in this way used that the first receiving area 40 of the support structure 34 to the first contact area 18 of the cover element 2 and the second receiving area 44 of the support structure 34 on the border the second contact area 16 of the cover element 2 and the support member 28 of the cover member 2 and the support member 48 of the support structure 34 overlap. This is a thermal expansion-tolerant fastening of the guide ring 15 made in the guide vane segment 25 of the turbine 9, whereby in particular the gap dimension of the gap 23, that is the distance between the outer end 27 of the blade 13 and the hot side 10 of the guide ring 15 to a defined dimension can be adjusted. The detailed design and functionality of this thermal expansion elastic fastening concept is explained in detail in FIGS. 8 and 9.

A perspective view of a guide ring 15 a Gas turbine 1 is shown in FIG. 3. The guide ring 15 extends along a longitudinal axis 4 and a transverse axis 6. It comprises a wall 8 with a hot medium exposed hot side 10 and one opposite the hot side 10 Cooling side 12, one with a coolant K has actable cooling surface 14. On the wall 8 of the Guide ring 15 borders a first along the longitudinal axis 4 Contact area 16 with a first contact surface 20. On second contact area 18 with a second contact surface 22 borders on the wall 8 along the longitudinal axis 4 and lies opposite the first contact area 16. The guide ring 15 also has a wall 8 along the transverse axis 6 adjacent first edge region 24 and one along the Transverse axis 6 opposite the first edge region 24 second edge region 26. Compared to the first / second Edge area 24, 26 and the first / second support area 16, 18, the wall 8 is made thin.

On the cooling side 12 of the wall 8, support elements 28 are provided, which are arranged between the first and the second support area 20, 22. Here, five mounting elements 28 are arranged along the transverse axis 6 on the cooling side 12 of the wall 8. The first and second edge regions 24, 26 each have a mounting element. 28, while three mounting elements 28 are arranged on the cooling surface 14 of the wall 8. The mounting elements 28 are an integral part of the guide ring 15 and have the function of providing additional support between the first and the second support areas 16, 18. The guide ring 15 can be held by the holding elements 28 from the cooling side in such a way that, in particular, forces which are normal to the wall, for example as a result of mechanical and / or thermal loading of the wall 8, can be efficiently absorbed and, if appropriate, also transmitted. The mounting elements 28 each have a recess 32, in particular a groove, with a mounting contact surface 30. The respective recess 32 in the holding elements 28 is provided for engagement in a support structure 34, not shown in FIG. 3 (see FIGS. 8 and 9). In this way, with the holding elements 28, in combination with the first and the second support areas 16, 18 and with a support structure 34 (not shown in FIG. 3), a thermal expansion-tolerant connection between the guide ring 15 and the support structure 34 is achieved. Due to the fact that the first and the second support areas 16, 18 adjoin the wall 8 along the longitudinal axis 4, the side of the wall 8 opposite the hot medium M is practically completely available as a cooling surface 14. With this design, the cooling surface 14 can be acted upon uniformly with a coolant K, for example cooling air, which enables very homogeneous cooling. The holding elements 28 are arranged at a distance from one another along the transverse axis 6, as a result of which the cooling surface 14 is designed as a coherent surface and, as a result, the coolant K, if it is supplied at one point on the cooling side 12, can reach all areas of the cooling surface 14. This ensures an unimpeded and uniform distribution of the coolant K along the cooling surface 14 and thus also a particularly efficient, area-wide heat dissipation. The cooling surface 14 has a support structure 36. This serves to increase the rigidity and thermal conductivity of the guide ring 15.
This support structure is embodied by a series of equidistant longitudinal ribs 38 which uniformly cover the cooling surface 14 along the transverse axis 6. Both longitudinal ribs 38 are provided, which extend from the first contact area 16 to the second contact area 18 of the guide ring 15, and also longitudinal ribs 38, which extend from the first contact area 16 along the longitudinal axis 4 and between the first contact area 16 and the second contact area 18 of the guide ring 15 end on the cooling surface 14. The support structure 36 prevents deformations, in particular deformations and deflections of the wall 8 in the direction of the hot side 10 of the wall 8. Furthermore, this support structure 36 ensures an increase in the effective cooling surface 14, which leads to an increase in the cooling efficiency. In addition to increasing the effective cooling surface 14, the support structure 36 additionally brings about an improved mixing of coolant K with different temperatures in the immediate vicinity of the cooling surface 14. As a result, the temperature on the cooling surface 14 is reduced on average, and the temperature gradient and, accordingly, the heat transport the coolant K is increased.
In addition, the thermal conductivity is increased somewhat due to the enlarged cross section of the support structure 36 along the support structure.

The mounting elements arranged on the cooling surface 14 28 are with at least three in the direction of the transverse axis 6 spaced longitudinal ribs 38 connected. Through this constructive Design, the support members 28 on the Cooling surface 14 to a certain extent as part of the support structure 36 be understood. This version serves both the increase the rigidity as well as the increase in thermal conductivity, but above all the mechanical and thermal stability the guide ring 15 at high temperature and / or pressure loads, especially when there is a change in temperature. easy Manufacturing forms of the guide ring 15 with these cheap Properties, such as castings, are possible.

FIG. 4 shows a guide ring 15 of a gas turbine 1 an alternative to Figure 3 arrangement of the support members 28 and configuration of the longitudinal ribs 38 on the Cooling side 12, and Figure 5 is a view of that shown in Figure 4 Guide ring 15 along the section line VI-VI. there Figure 4 shows a plan view of the cooling side 12 of the Guide ring 15, which can be acted upon with a coolant Has cooling surface 14. The cooling surface 14 will along the longitudinal axis 4 through a first support area 16 and one along the longitudinal axis of the first support area 16 opposite second support area 18 limited. Along the transverse axis 6, the cooling surface 14 by a adjacent first edge region 24 and one along the Transverse axis 6 opposite the first edge region 24 limited second edge region 26. In contrast to that in FIG. 3 The exemplary embodiment shown are the five mounting elements 28 arranged exclusively on the cooling surface 14, i.e. the first and second edge areas 24, 26 of the guide ring 15 has no mounting elements 28 here. On the Cooling surface 14 is a support structure 36 in the form of equidistant Longitudinal ribs 38 which extend from the first contact area 16 along the longitudinal axis 4 to the second contact area 18 extend and the cooling surface 14 evenly from cover the first edge area 24 to the second edge area 26.

At least two are spaced apart in the direction of the transverse axis 6 Longitudinal ribs 38 connected to a support member 28. There are five mounting elements 28 on the cooling surface 14 spaced apart. The cooling surface 14 is thus designed as a coherent surface, and a coolant K, in particular cooling air L, can from one location on the cooling surface 14 to any one elsewhere on the cooling surface 14 unhindered stream. Elaborate coolant supply or coolant feedthroughs so you don’t have to make it special efficiently coolable guide ring 15 provided.

The sectional view shown in Figure 5 of that shown in Figure 4 Guide ring 15 shows a wall 8 with a hot one Medium exposed hot side 10 and one of the hot side 10 opposite cooling side 12, one with a coolant K has cooling surface 14 which can be acted upon. Along the Longitudinal axis 4 borders wall 8, a first support area 16 with a first bearing surface 20. A second Support area 18 borders with a second support surface 22 along the longitudinal axis 4 to the wall 8 and is the first Support area 16 opposite. On the cooling surface 14 are two support elements 28 along the longitudinal axis 4 to each other spaced apart, being a contiguous Cooling surface 14 is formed. The bracket elements 28 each have a recess 32, in particular a groove Bracket support surface 32 for engaging one in the figure 5, not shown, support structure 34 (see FIGS. 8 and 9). The wall 8 is designed with a wall thickness D1 opposite the wall thickness of the first and the second contact area 16, 18 is made comparatively thin. The wall thickness D1 is approximately 1.0 mm to 5.0 mm, in particular approximately 1.5 mm to 3.0 mm. This has an advantageous effect on the cooling properties of the guide ring 15. Depending on the application the temperature difference between that with the hot medium M acted upon hot side 10 and the coolant K actable cooling side 12 of the wall 8 be very large. To the Example can be used in a guide ring 15 Gas turbine 1 temperature differences between the hot gas and the cooling air of up to 800 ° C occur. Therefore it is convenient make the wall 8 as thin as possible so that the temperature gradient between hot side 10 and cooling side 12 of the Wall 8 becomes as large as possible and the heat is very efficient the lowest possible use of coolant can be removed. Efficient heat dissipation takes place primarily through the Cooling air K. A smaller part of the heat flow from the Hot side 10 flows into the wall 8, but is also along the Longitudinal axis and the transverse axis in the first / second support area and the first / second edge region of the cover element derived because this area because of its opposite wall 8 larger cross section form a heat sink.

Figure 6 shows a further embodiment of a guide ring 15 a gas turbine 1 with cooling surface 14 and Bracket elements 28, and Figure 7 is a view of the figure 5 shown guide ring 15 along the section line VII-VII. The guide ring 15 shown is dimensioned such that that it is predominantly along the longitudinal axis 4 extends. The longitudinal axis 4 therefore forms the preferred direction of expansion of the guide ring 15. Therefore, on the Cooling surface 14 three mounting elements 28 along the Longitudinal axis 4 spaced apart, one coherent cooling surface 14 is formed. Further points the first edge area 24 and the second edge area 26 each a support member 28. On the cooling surface 14 is a support structure 36 in the form of equidistant longitudinal ribs 38 executed along the longitudinal axis 4. The longitudinal ribs 38 extend from the first support area 16 to second support area 18 and cover the cooling surface 14 evenly along the transverse axis 6 of the guide ring 15. The bracket elements 28 are each with a Recess 32, which has a mounting support surface 30, Mistake. The recesses 32 are designed here as grooves, the for engaging in a support structure, not shown in Figure 6 34 (see Figures 8 and 9) serve.

The sectional view VII-VII in Figure 7 shows a wall 8 with a hot side 10 which can be exposed to a hot medium M and one the cooling side 12 opposite the hot side 10, the a cooling surface 14 to which a coolant can be applied having. The one adjacent to the wall 8 along the longitudinal axis 4 first contact area 16 has a first contact surface 20 on. A second contact area 18 with a second contact surface 22 is adjacent to the wall 8 along the longitudinal axis 4 and lies opposite the first contact area 16. Analogous to The exemplary embodiment in FIGS. 4 and 5 is wall 8 compared to the first and second contact areas 16, 18 comparatively executed thin.

In the operation of a gas turbine, i.e. under high thermal and mechanical load, has the wall 8 of the guide ring 15th the tendency to bend towards the hot side 10. The resulting deflection of the wall 8 depends on it depending on the temperature and pressure conditions that the guide ring 15 is subjected, as well as the material properties and the design of the guide ring 15, in particular with regard to the number and arrangement of the support elements 28 on the cooling surface 14.

With a typical temperature difference between hot side 10 and cooling side 12 of the guide ring 15 of about 800 ° C, such as it occurs, for example, in a stationary gas turbine 1, there are values between 0.1 mm and 0.7 mm for the thermal deflection of the wall 8. In a specific task you become with the design and layout of a gas turbine 1, for example by means of a computer-aided optimization process, a suitable design for the guide ring Reach 15.

The competing requirements between the Deflection of the wall 8 on the one hand, and associated therewith the number and arrangement of the support elements 28 on the Cooling surface 14, and the largest possible effective Cooling surface 14, on the other hand, is taken into account.

The exemplary embodiments show that the proposed concept a big one with regard to a specific task Offers flexibility.

FIG. 8 shows a longitudinal section of an arrangement of a cover element 2, which represents a guide ring 15, in the guide vane segment 25 of a gas turbine 1 without thermal stress, ie at room temperature. The guide ring 15 comprises a wall 8 with a wall thickness D1 and with a hot side 10 which can be exposed to a hot medium M and a cooling side 12 opposite the hot side which has a cooling surface 14 which can be acted upon by a coolant K. Along the longitudinal axis 4 of the wall 8, a first bearing area 16 adjoins the wall 8 with a first bearing surface 20. A second contact area 18 with a second contact surface 22 is adjacent to the wall 8 along the longitudinal axis 4 and is opposite the first contact area 16. A holding element 28 is arranged on the cooling surface 14, which has a recess 32, in particular a groove, and a holding contact surface 30. The holding element 28 is designed and arranged on the cooling surface 14 in such a way that a coherent cooling surface 14 is formed. The guide vane segment 25 has a support structure 34 into which the guide ring 15 is inserted. The support structure 34 extends along a longitudinal axis 4 and has a first receiving region 40 with a first receiving surface 42 and a second receiving region 44 opposite along the longitudinal axis with a second receiving surface 46 and a supporting element 48 with a supporting surface 50. The guide ring 15 is arranged in the support structure 34 in such a way that the first receiving area 40 adjoins the first contact area 16 and the second receiving area 44 adjoins the second contact area 18 and the mounting element 28 and the mounting element 48 overlap, the mounting contact surface 30 and the supporting surface 50 face each other. In the case shown here without thermal stress, ie at room temperature, the mounting support surface 30 and the support surface 50 are spaced apart from one another by a gap 52. The configuration formed between the first receiving area 40 and the adjoining first contact area 16 is designed as a floating bearing 56. The configuration formed between the second receiving area 44 and the adjoining second contact area 18 is designed as a fixed bearing 54. The design with a fixed bearing 54 and a floating bearing 56 facilitates the assembly of the guide ring 15 in the support structure 34 in the thermally unloaded state. At the same time, thermal expansion of the guide ring 15 along the longitudinal axis 4 is made possible in the event of a load. In the event of a temperature rise, the thermal expansion takes place from the fixed bearing 54 in the direction of the floating bearing 56. The fixed bearing configuration is designed such that the second receiving area 44 and the adjoining second contact area 18 come into contact with one another even with a slight rise in temperature compared to the room temperature. The fixed bearing is designed with a tolerance between approximately 0.2 mm to 0.5 mm. The floating bearing 56, however, is dimensioned so that the guide ring 15 can expand along the longitudinal axis 4 even at high temperatures. In the arrangement, the floating bearing has a tolerance between approximately 4 mm to 10 mm. The guide ring 15 is usually inserted into the support structure 34 at room temperature. Because the first receiving area 40 adjoins the first contact area 16 and the second receiving area 44 adjoins the second contact area 18, the guide ring 15 is already held in the support structure 34. The spacing of the mounting support surface 30 of the mounting element 28 and the support surface 50 of the support element 48 by a gap 52 facilitates the assembly of the guide ring 15 in the support structure 34. The guide ring 15 is a cover element 2 in a gas turbine 1 between the platforms (not shown in FIG. 8) of two axially spaced-apart guide vanes 7 (see FIGS. 1 and 2). The gap 23, which is formed between the outer end 27 of the rotor blade 13 and the hot side 10 of the wall 8, has a gap dimension δ ₀ at room temperature.

FIG. 9 illustrates the behavior of the system discussed in FIG. 8 under thermal loading, that is to say in the operation of a stationary gas turbine 1. During operation of the gas turbine 1, ie under high thermal and mechanical loads, the wall 8 of the guide ring 15 has the tendency to bend in the direction of the hot side 10. As a result, the mounting support surface 30 and the support surface 50 come to coincide, and the forces due to the thermal and mechanical loads are absorbed effectively. The distance selected between the support surface 30 and the support surface 50 at room temperature (cf. FIG. 8) has a significant influence on the thermal load at which the support support surface 30 and the support surface 50 come to congruence, and consequently on the resulting thermal deflection D2 of the wall 8 In the thermally highly loaded state, the guide ring 15 is thus held firmly in the support structure 34. The gap 23 formed between the hot side 10, which is exposed to the hot medium M, in particular the hot gas, and the outer end 27 of the rotor blade 13 has a gap dimension δ ₁ that is smaller than the gap dimension δ ₀ at room temperature (see FIG. 8 ). The difference between these gap dimensions δ ₀ , δ ₁ corresponds approximately to the thermal deflection D2 of the wall 8. The resulting thermal deflection D2 depends on the temperature and pressure load on the guide ring 15, and on the material properties and the structural design, in particular with regard to the Number and arrangement of the holding elements 28 on the cooling surface 14. The gap dimension δ ₁ can be set to a predetermined, as small as possible, dimensioning the arrangement shown. The gap losses due to the mass flow of hot medium M, in particular hot gas, through the gap 23 can be minimized in this way, which has a positive effect on the turbine efficiency. At the same time, grinding of the rotating rotor blade 13 against the guide ring 15 can be reliably prevented during operation. Since the pressure difference between the cooling side 12 and the hot side 10 of the guide ring 15 increases continuously and uniformly when the cooling surface 14 is exposed to coolant K along the longitudinal axis 4, due to the expansion of the hot medium M along the longitudinal axis 4, it is preferably the downstream one formed bearing configuration as a fixed bearing 54 and the upstream bearing configuration designed as a floating bearing 56. This ensures free thermal expansion of the guide ring 15 along the longitudinal axis 4. The thermal expansion takes place when the temperature rises from the fixed bearing 54 in the direction of the floating bearing 56. The fixed bearing configuration, in particular the fixed bearing 54, is designed such that the receiving area 44 and the adjacent bearing area 18 come into contact with one another even with a slight rise in temperature compared to the room temperature , so that in particular the receiving surface 40 and the bearing surface 22 lie directly opposite one another. The floating bearing 56, however, is designed so that the guide ring 15 can expand sufficiently along the longitudinal axis 4 even at high temperature loads.

Claims (19)

1. Covering element (2) which has a longitudinal axis (4) and a transverse axis (6), comprising

   a) a wall (8) with a hot side (10) capable of being exposed to a hot medium (M) and with a cool side (12) which is located opposite the hot side (10) and which has a cooling surface (14) capable of being acted upon by a coolant (K),

   b) a first bearing region (16) contiguous to the wall (8) along the longitudinal axis (4) and having a first bearing surface (20) and a second bearing region (20) located opposite the first bearing region (16) along a longitudinal axis (4) and having a second bearing surface (22),

   c) a first edge region (24) contiguous to the wall (8) along the transverse axis (6) and a second edge region (26) located opposite the first edge region (24) along the transverse axis (6),

   characterized in that a holding element (28), which is arranged between the first and the second bearing region (16, 20), is provided on the cool side (12), the edge regions (24, 26) and the bearing regions (16, 22) delimiting the cooling surface (14) in such a way that the cooling surface (14) is formed as a coherent surface, so that an unimpeded and uniform distribution of the coolant (K) along the cooling surface (14) can be achieved.
2. Covering element (2) according to Claim 1, characterized in that a further holding element (28) is arranged on the cooling surface (14) on the first or on the second edge region (24, 26).
3. Covering element (2) according to Claim 1 or 2, characterized in that the holding element (28) has a holding bearing surface (30).
4. Covering element (2) according to Claim 1, 2 or 3, characterized in that the holding element (28) has a recess (32), in particular a groove, for engaging into a carrying structure (34).
5. Covering element (2) according to one of Claims 1 to 4, characterized in that the wall (8) has a wall thickness (D1) of between about 1.0 mm and 5.0 mm, in particular between about 1.5 mm and 3.0 mm.
6. Covering element (2) according to one of Claims 1 to 5, characterized in that the cooling surface (14) has a supporting structure (36) for increasing the rigidity and thermal conductivity.
7. Covering element (2) according to Claim 6, characterized in that the supporting structure (36) is formed by at least one longitudinal rib (38) on the cooling surface (14) along the longitudinal axis.
8. Covering element (2) according to Claim 7, characterized in that the supporting structure (36) has a further longitudinal rib (38) which is formed on the cooling surface (14) along the longitudinal axis (4).
9. Covering element (2) according to Claim 7 or 8, characterized in that at least two longitudinal ribs (38) spaced from one another in the direction of the transverse axis (6) are connected to a holding element (28).
10. Covering element (2) according to one of the preceding claims, characterized in that the number and arrangement of the holding elements (28) are defined by a predetermined thermal flexion (D2) of the wall.
11. Covering element (2) according to Claim 10, characterized in that the predetermined thermal flexion (D2) is about 0.1 mm to 1.0 mm, in particular about 0.3 mm to 0.7 mm.
12. Covering element (2) according to Claim 10 to 11, characterized in that at least two holding elements (28) are arranged, spaced from one another, along the transverse axis (6).
13. Covering element (2) according to Claim 10, 11 or 12, characterized in that at least two holding elements (28) are arranged, spaced from one another, along the longitudinal axis (4).
14. Arrangement with a covering element (2) according to one of the preceding claims and with a carrying structure (34) which has

    a) a longitudinal axis (4) and a transverse axis (6),

    b) a first receiving region (40) arranged along the longitudinal axis (4) and having a first receiving surface (42),

    c) a second receiving surface (44) located opposite along the longitudinal axis (4) and having a second receiving surface (46), and

    d) a carrying element (48) with a carrying surface (50),

    characterized in that the first receiving region (40) is contiguous to the first bearing region (16) and the second receiving region (44) to the second bearing region (20) and the holding element (28) and carrying element (38) overlap one another, the holding bearing surface (30) and the carrying surface (50) being located opposite one another.
15. Arrangement according to Claim 14, characterized in that, without any thermal load, in particular at room temperature, the holding bearing surface (30) and the carrying surface (50) are spaced from one another by a gap (52).
16. Arrangement according to Claim 14 or 15, characterized in that a configuration formed between the receiving region (40, 44) and the bearing region (16, 18) contiguous to it is designed as a fixed bearing (54) and the other configuration as a loose bearing (56).
17. Arrangement according to Claim 16, characterized in that the fixed bearing (54) has a tolerance of between about 0.2 mm and 0.5 mm.
18. Arrangement according to Claim 16, characterized in that the loose bearing (56) has a tolerance of between about 4 mm and 10 mm.
19. Arrangement according to one of Claims 14 to 18, characterized in that the covering element (2) and the carrying structure (34) are arranged in a thermal machine, in particular in a gas turbine (1).

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