EP1283328A1 - Sealing bushing for cooled gas turbine blades - Google Patents

Abstract

The gas turbine has a number of turbine blades (12), each fitted to a turbine shaft via a blade foot (20) and having an internal cooling medium channel (24) coupled to cooling medium feed and return channels (26,34) integrated in the turbine shaft. The connection ends of the feed and return channels each have a widened cross-section and a matching cross-section sealing sleeve (30,36) which can slide in the longitudinal direction.

Description

The invention relates to a gas turbine with a number arranged on a turbine shaft via a blade root Blades, each with an integrated coolant channel exhibit.

Gas turbines are used to drive generators in many areas or used by work machines. The Energy content of a fuel to generate a rotational movement a turbine shaft. The fuel will To do this, burned in a combustion chamber, using an air compressor compressed air is supplied. That in the combustion chamber generated by the combustion of the fuel, under high pressure and working medium at high temperature is via a turbine unit downstream of the combustion chamber managed where it relaxes while working.

To generate the rotational movement of the turbine shaft are a number of them usually in groups of blades or rows of blades grouped together arranged, via a pulse transfer from the working medium drive the turbine shaft. For guiding the working medium in the turbine unit are usually between neighboring rows of blades with the turbine housing connected rows of vanes arranged.

When designing such gas turbines in addition to achievable performance usually a particularly high efficiency a design goal. An increase in efficiency can basically be done for thermodynamic reasons by increasing the outlet temperature, with which the working medium from the combustion chamber and into the Turbine unit flows. Therefore temperatures of around Desired 1200 ° C to 1300 ° C for such gas turbines and also achieved.

At such high temperatures of the working medium however, the components and parts exposed to it are high exposed to thermal loads. To still at high Reliability has a comparatively long lifespan Ensuring affected components is common cooling of the affected components, in particular of Rotor and / or guide vanes of the turbine unit are provided. The turbine blades are therefore usually designed to be coolable, being particularly effective and reliable Cooling seen in the flow direction of the working medium first rows of blades should be ensured. For cooling the respective turbine blade usually has one integrated into the airfoil or the airfoil Coolant channel from which a coolant is targeted especially the thermally stressed zones of the turbine blade is feedable.

Cooling air, for example, is used as the coolant. This is usually the case for the respective turbine blade in the manner of open cooling via an integrated one Coolant channel supplied. Flowing through from this the cooling air in the branching ducts are provided Areas of the turbine blade. Are on the outlet side these channels left open so that the cooling air after the Flow through the turbine blade and exits with the working medium in the turbine unit mixed.

In this way, a comparatively simple means reliable cooling system available for the turbine blade, Zones of the particularly thermally stressed Turbine blade suitable coolant can be applied. On the other hand, however, when the cooling air is introduced into the working medium guided in the turbine unit towards it make sure that your pressure is that of the working medium at the feed point exceeds, so that a smooth initiation of the Cooling air is allowed. In particular, the permissible too Heating of the cooling air when cooling the turbine blades only limited, so that the target is comparatively high Outlet temperatures of the working medium a special large amount of cooling air is required. This works in turn adversely affect the efficiency of the gas turbine and on nitrogen oxide emissions.

A desirable saving in cooling air requirement for these reasons is achievable by keeping the cooling system closed Cooling system is formed. With such a closed cooling system is the used coolant, especially cooling air, returned to the combustion process. Especially with such a closed cooling system, in which the cooling air has a comparatively high pressure loss may be subject to, but is usually a local and customized supply of cooling air depending on the intended feed point is comparatively high pressure required. This includes the pressure loss when guiding the cooling air through a closed system to consider. Especially with comparatively long ones Systems can increase pressure loss significantly contribute to the requirements for the cooling air to be provided. Especially the provision of cooling air with comparatively however, high pressure means that it is comparatively complex Construction of the associated systems, in particular at high pressure requirements to provide the Cooling air compressors required depending on the operating conditions those achievable through closed cooling Efficiency or performance advantages partially or even can fully compensate.

In order to avoid pressure losses when supplying the coolant To keep it low, there is a requirement at transition points the coolant channel to a high level of tightness guarantee. There is a critical transition point all the connection of the coolant channel arranged in the blade root a blade to one in the turbine shaft arranged channel for supplying the coolant; because just now the inlet surface of the coolant channel in the blade root is subject to considerable centrifugal force as well a high thermal load. Therefore, the construction-related - among other things for assembly purposes - anyway existing gap between the mouth of the in the Turbine shaft integrated coolant channel and the inlet opening for the coolant in the blade root during operation open the gas turbine to a degree that requires a seal to avoid loss of coolant.

The problem described is also of particular importance, if different types of coolant are in the blade, z. B. cooling air or steam with different pressure for fore and aft Trailing edge of the shovel. In this Case, the respective connections must be sealed against each other to prevent the coolant from mixing. This can be done by adjacent inlet openings in the same blade root for different coolants as far apart as possible be placed away so that crosstalk cannot occur. That is e.g. B. with the help of so-called Mini discs, one at the front and another at the back Blade foot is attached instead of actual channels too to reach. However, the mini discs can have leakage problems between adjacent areas and thus one require increased sealing effort. You can also no intersecting supply lines for coolant flows be relocated so that the possible uses are restricted are.

The invention is therefore based on the object of a gas turbine of the type mentioned above, in the case of a safe cooling of the blades of the coolant requirement is kept particularly low and a reliable separated Feeding the blades with various coolants, especially with cooling air of different pressures, at particularly low service requirements.

This object is achieved according to the invention by one a blade associated with the turbine shaft Supply channel for coolant in an outlet side End area is expanded in its cross section, and in the end area with an outer contour on the inner cross section adapted to the end region, in its longitudinal direction slidable feed bushing is arranged.

The invention is based on the consideration that for one of the needs for coolant for reliable cooling the blades can be kept particularly low if a coolant leakage is largely excluded, and that on the other hand a higher flexibility of cooling can be achieved is chosen by designing the cooling can have various leads attached close to each other are. Both can be realized if a reliable one Seal between the supply channel for coolant in the Turbine shaft and the coolant channel in the blade can be provided. This in turn is done with simple Funds achieved through targeted use of the company or gas turbine centrifugal force. The socket, the hollow is for the passage of the coolant, then the Center axis of the turbine shaft pressed outward and is therefore on the underside of the blade root. Thereby there is a good sealing effect because the centrifugal force is very high is high. As experiments have shown, it can be in the range of 10,000 g, with g being the acceleration due to gravity is designated.

With open cooling, there is no return of the coolant, but this occurs after flowing through the turbine blade out of this and mixes with the Working medium. In contrast, one is special effective closed cooling, the coolant is returned, why in the turbine shaft a drain channel for used Coolant is arranged. Because the pressure of the coolant in the course of the coolant channel in the turbine blade decreases and there is a risk of crosstalk between different channels essentially when entering the Vane exists, could be in the transition from the coolant duct in the discharge channel in some cases to an additional one Seal be dispensed with. It is particularly advantageous however, if a blade assigned to each blade in the turbine shaft has an integrated drainage channel for coolant in an entry-side initial area in its cross section is expanded, with one in its initial range Outer contour adapted to the inner cross section of the starting area longitudinally displaceable lead bushing is arranged. In this way, both the coolant supply line as well as the coolant drainage Cooling effect reinforcing a highly effective seal of the coolant.

The sealing effect can in particular without additional components can be further advantageously increased if an inlet assigned to the supply duct and / or a Discharge channel assigned outlet of the coolant channel in an essentially flat, the end of the Supply channel and / or the initial area of the discharge channel facing contact surface of the respective blade root empties. Thus, the feed bushing and if necessary the discharge socket is extremely safe during operation of the gas turbine and with a large contact surface flat against the contact surface of the blade root, which prevents any leakage becomes.

For a particularly stable position of the rotor blade on the turbine shaft and thus a secure seal of the coolant channel also over a long service life of the gas turbine ensure the blade root can be advantageous in one Disk groove can be arranged on the turbine shaft. At a such an embodiment, it would be conceivable in principle Supply channel and possibly also the discharge channel for coolant in the lateral direction of the turbine shaft in the blade root and the coolant channel guided in this to let it flow. The best possible sealing effect results but if the outlet-side end region of the supply duct and / or the entry-side initial area of the Discharge channel arranged in the groove base of the disc groove is because in this way the centrifugal force is at full height Effect of the seal.

Sealing of the coolant channel is also achieved if the feed bushing and, if necessary, the discharge bushing is displaceable on a straight line which is the central axis of the Turbine shaft does not cut. In this case it just does the component running in the direction of the straight line the centrifugal force the seal. A particularly good sealing effect is achieved when the feed bushing is advantageous and / or the lead bushing related to the central axis the turbine shaft are / is radially displaceable. Consequently the feed bushing and / or the discharge bushing is exact oriented towards the centrifugal force, which is their optimal Use for sealing possible.

To further reduce the leakage is advantageous also sealing the outside of each Socket with the associated channel piece formed annulus intended. In a particularly advantageous embodiment, the respective bushing on their facing away from the blade root Tapered end and with a circumferential sealing ring Mistake.

Air is preferably provided as the coolant in the gas turbine, that is particularly easy to provide in this case and is manageable.

The advantages achieved with the invention are in particular in that by the displaceable in its longitudinal direction Coolant supply bushing in the end area of a arranged in the turbine shaft supply duct and fitted into it, one in the operation of the gas turbine with the centrifugal force increasing seal from the supply channel and a coolant channel in a blade is, whereby different supply lines are placed close to each other can be prevented and loss of coolant becomes. In addition, a recess, for example a bore, to provide the end region of the supply duct as well as the socket as such with extremely small manufacturing tolerances producible, since this is preferably Round body. Due to the small tolerances is a high sealing effect also along the longitudinal direction of the bush achievable. The respective blade is also special can be assembled or disassembled with little effort.

Figur 1

einen Halbschnitt durch eine Gasturbine,

Figur 2

einen vergrößerten Halbschnitt durch eine Laufschaufel der Gasturbine nach Figur 1,

Figur 3

eine Explosionsdarstellung eines Verbindungsbereichs einer Turbinenwelle mit einer weiteren Laufschaufel, und

Figur 4

im Ausschnitt eine Zuführungs- oder Ableitungsbuchse.

An embodiment of the invention is explained in more detail with reference to a drawing. In it show:

Figure 1

a half-section through a gas turbine,

Figure 2

2 shows an enlarged half section through a rotor blade of the gas turbine according to FIG. 1,

Figure 3

an exploded view of a connection area of a turbine shaft with a further blade, and

Figure 4

in the cutout a feed or discharge socket.

The same parts have the same reference symbols in all the figures Mistake.

The gas turbine 1 or FIG. 1 has a compressor 2 for Combustion air, a combustion chamber 4 and a turbine 6 for Drive the compressor 2 and a generator, not shown or a work machine. To do this are the turbine 6 and the compressor 2 on a common, also as a turbine rotor designated turbine shaft 8 arranged with the the generator or the working machine is also connected and which is rotatably mounted about its central axis 9.

The combustion chamber 4 is provided with a number of burners 10 Combustion of a liquid or gaseous fuel. It is still not closer to its inner wall provided heat shield elements.

The turbine 6 has a number of with the turbine shaft 8 connected, rotatable blades 12. The blades 12 are arranged in a ring shape on the turbine shaft 8 and thus form a number of rows of blades. Farther the turbine 6 comprises a number of fixed guide vanes 14, which is also ring-shaped with the formation of Guide vane rows attached to an inner wall 16 of the turbine 6 are. The blades 12 serve to drive the Turbine shaft 8 by momentum transfer from the turbine 6 flowing through Working medium M. The guide vanes 14, however, serve to flow the working medium M between each two seen in the flow direction of the working medium M. successive rows of blades or blade rings. A successive pair from a wreath of Guide vanes 14 or a row of guide vanes and from one Wreath of blades 12 or a row of blades is also referred to as the turbine stage.

Each guide vane 14 has one which is also referred to as a blade root Platform 18, which is used to fix the respective guide vane 14 on the inner wall 16 of the turbine 6 as a wall element is arranged. The platform 18 is a thermal comparison heavily loaded component that the outer boundary a hot gas duct for the one flowing through the turbine 6 Working medium M forms. Each blade 12 is analog Way over a platform 20 also referred to as a blade root attached to the turbine shaft 8.

Between the spaced platforms 18 of the guide vanes 14 of two adjacent rows of guide vanes is a guide ring 21 on the inner wall 16 of the Turbine 6 arranged. The outer surface of each guide ring 21 is also hot, flowing through the turbine 6 Working medium M exposed and in the radial direction from the outer end 22 of the blade opposite to it 12 spaced by a gap. The between Guide rings 21 arranged adjacent rows of guide vanes serve in particular as cover elements that cover the inner wall 16 or other housing installation parts before a thermal Overuse by the flowing through the turbine 6 protects hot working medium M.

To achieve a comparatively high efficiency the gas turbine 1 for a comparatively high outlet temperature of the working medium emerging from the combustion chamber 4 M designed from about 1200 ° C to 1300 ° C. In order to make this possible, are at least some of the blades 12 and Guide vanes 14 designed to be coolable as cooling medium by cooling air.

In Figure 2 is by means of a blade root 20 on the Turbine shaft 8 arranged blade 12 of the gas turbine shown enlarged. The blade 12 has an in they integrated coolant channel 24, the course of which here is reproduced only in a highly simplified manner, and therefore is drawn in dashed lines. In the coolant channel 24 Air as coolant K to reduce the thermal load the blade 12 guided, a feeding of the Coolant channel 24 through an integrated in the turbine shaft 8, here only simplified supply channel 26 takes place. The flow direction of the coolant K becomes indicated by arrows 28. In its outlet end area 30, the supply channel 26 is expanded, and in this End region 30 is a displaceable in its longitudinal direction L1 Feed bushing 32 arranged. The outer contour of the Feed bushing 32 is on the inside cross section of the end portion 30 of the feed channel 26 adapted so that the socket 32 sealing on the inner wall of the feed channel 26 is applied.

The blade 12 has a closed cooling, what means that the coolant K is derived from the blade 12 and is returned. This derivation and return takes place by means of an integrated in the turbine shaft 8 Discharge channel 34. The transition from the coolant channel 24 to Discharge channel 34 is analogous to the transition from the feed channel 26 to the coolant duct 24: the discharge duct 34 is in an entry-side initial area 36 with a expanded cross-section, being in the initial area 36 a lead bushing displaceable in its longitudinal direction L2 38, the outer contour of the inner cross section of the Starting area 36 is sealingly adapted, is arranged. Both the feed bushing 32 and the drain bushing 38 are related to the central axis 9 of the turbine shaft 8 radially displaceable.

When the gas turbine is operating, it opens due to the centrifugal force a gap 40 between the blade root 20 and the turbine shaft 8. At the same time, however - also due to the centrifugal force - Both the feed bushing 32 and the discharge bushing 38 in the cross-sectional end region 30 of the feed channel 26 and in the cross-section expanded Initial area 36 of the discharge channel 34 to the outside, i. H. towards the blade root 20. After bridging gaps 42, 44 in the end area 30 and in the start area 36 come the feed bushing 32 and the drain bushing 38 on the blade root 20 to the system, so that both the Transition from the supply channel 26 to the coolant channel 24 as also laterally from the coolant channel 24 to the discharge channel 34 remains closed without leakage. Even with an enlargement of the gap 40, e.g. B. caused by an increase in Speed of the turbine shaft 8, the channel transitions are sealed, since the sockets 32, 38 permanently and when enlarged corresponding to the centrifugal force against the blade root 20 are pressed.

An exploded view of a connection area of a Turbine shaft 8 with a further blade 12 one The gas turbine is shown in FIG. 3. There is a coolant channel 24 having blade root 20 in a disk groove 46 on the Turbine shaft 8 arranged. Furthermore, the turbine shaft 8 with a feed channel 26 and a drain channel 34 for Provide coolant, the supply channel 26 in one End area 30 and the discharge channel 34 in an initial area 36 is provided with a cross-sectional expansion. In the end portion 30 is a feed bush 32 and in the Starting area 36 a lead bushing 38 slidably mounted.

An inlet 48 assigned to the inlet channel 26 and an inlet Outlet channel 34 associated outlet 50 of the coolant channel 24 ends in a contact surface that has just been executed 52, the end portion 30 of the feed channel 26 and the Starting area 36 of the discharge channel 34 faces. At the Operation of the gas turbine is due to the centrifugal force Bushes 32, 38 pressed against the flat contact surface 52, which creates tight transitions between channels 24, 26, 34 result. For this purpose, both the exit-side end region 30 of the feed channel 26 and the inlet side Initial region 36 of the discharge channel 34 in the groove base 54 the disc groove 46 arranged.

The discharge channel 34 shown in FIG. 3 could also be a be another supply channel through which another coolant than the blade root 20 through the feed channel 26 is feedable. For the formation of the sockets 32, 38 in the extended areas 30, 36 of the channels 26, 34 and the Blade foot 20 would not result in any changes. By using the bushings 32, 38 in the operation of the gas turbine achieved sealing is a crosstalk between the Channels 26, 34 excluded.

As shown in the embodiment of Figure 4, the Guide bush 32 and / or the department bush 38 on her respective end 60 facing away from the blade root 18 or 20 be beveled. This makes an assigned Sealing ring 62 can be used, the annular space 64 between the respective bushing 32, 38 and the inner wall of the end region 30 or the initial area 36 seals. So are also through the annulus 64 possibly occurring leaks reliably prevented.

Claims (7)

Gas turbine (1) with a number of over a blade root (20) on a turbine shaft (8) arranged rotor blades (12), each with an integrated coolant channel (24) comprising a rotor blade (12), supply duct integrated in the turbine shaft (8) (26) for coolant (K) in an outlet-side end area (30) is expanded in its cross section and being in the end region (30) one in its outer contour to the inner cross section the end region (30) adapted in its longitudinal direction (L1) slidable feed bushing (32) is arranged. Gas turbine according to claim 1, wherein each one Blade (12) assigned to the turbine shaft (8) Integrated drainage channel (34) for coolant (K) in one cross section of the entry-side initial region (36) is expanded, with one in its in the initial area (36) Outer contour on the inner cross section of the starting area (36) adapted, in its longitudinal direction (L2) movable lead bushing (38) is arranged. Gas turbine according to claim 1 or 2, wherein one of the supply duct (26) assigned inlet (48) and / or a Discharge channel (34) assigned outlet (50) of the coolant channel (24) in an essentially flat, the end region (30) of the feed channel (26) and / or the Start area (36) of the discharge channel (34) facing the contact surface (52) of the respective blade root (20) opens out. Gas turbine according to one of claims 1 to 3, wherein the Blade root (20) in a disk groove (46) on the turbine shaft (8) is arranged. Gas turbine according to claim 4, wherein the outlet side End region (30) of the feed channel (26) and / or the entry-side initial region (36) of the discharge channel (34) in the groove base (54) of the disc groove (46) is. Gas turbine according to one of claims 1 to 5, wherein the Feed bushing (32) and / or the discharge bushing (38) based on the central axis (9) of the turbine shaft (8) radially are / can be moved. Gas turbine according to one of claims 1 to 6, in which as a coolant Air is provided.

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