EP2453109B1 - Gas turbine arrangement and method for operating a gas turbine arrangement - Google Patents

Description

Technical area

The invention relates to a gas turbine arrangement having an annular space which is bounded axially between a rotor unit rotatable about a rotor axis and at least one stationary component and in which a plurality of coolant outlet openings open from the side of the at least one stationary component, from which in each case a coolant flow, usually in the form of cooling air, can be discharged into the annulus. In the flow direction of the flowing through the annulus from the side of the coolant outlet openings coolant flow are within the rotor unit coolant inlet openings into which passes at least a portion of the coolant flow, which is followed by at the Kühlmitteleinströmöffnungen within the rotor unit adjacent coolant lines to thermally stressed areas of the rotor unit or with the Rotor unit connected components is passed.

State of the art

A generic gas turbine arrangement is the DE 1221497 and the US 4,348,157 can be seen in which used for cooling the mounted on the rotor unit rotor blades cooling air is used, which is supplied via extending within stationary components of the gas turbine engine cooling channels and impinges on correspondingly arranged cooling channel openings on the rotor unit. Corresponding cooling air inlet openings are likewise provided on the rotor side, into which at least part of the supplied cooling air flows. The transfer of the cooling air from the stationary component side into the rotating rotor unit takes place within an annular space which is bounded on the one hand axially to the rotor axis of the rotor unit and the stationary component. Radially inward closes another, inner annular space, is introduced into the purge gas to protect rotor shafts near components of the rotor unit from friction-related overheating. For operational reasons, the purge gas immediately surrounding the rotor shaft is very strongly swirled and forms a pronounced swirl flow within the cavity. The pressure ratios in the respective regions of the gas turbine decrease with increasing radial shaft spacing, ie the purge gas present on the rotor shaft side is under a higher pressure compared to the pressure conditions within the annular space, which in turn are above the working pressure ratios within the hot gas channel.

It enters a radially directed leakage flow, which is directed from the inside, ie from the side of the rotor shaft near cavity through the radially inner ring seal assembly in the annulus and from there through the radially outer ring seal assembly in the main gas channel. It can be seen that the leakage flow radially passing through the leakage flow there for cooling purposes of the rotor unit existing cooling air flow whose flow direction is mainly oriented axially, can significantly irritate, thereby reducing the reaching into the coolant inlet portion of the cooling air flow and the cooling effect and the associated efficiency of the entire turbine arrangement significantly deteriorated.
The cooling air enters the turbine blade only with the required pressure when impinging on the intended flow direction. The more uniform the flow for entry into the blade root, the cheaper and more efficient the arrangement.

In the document cited above, it is proposed for this purpose to provide a deflecting device on the rotor side between the radially opposite annular sealing arrangements, which forces the leakage flow into radially extending channels, so that a flow path for the leakage flow is provided between the radially inner and outer ring seal assembly past the respective cooling channel openings.

Apart from the above-described property of not completely gas-tight ring seal assemblies through which forms a leakage flow, it is necessary to ensure a controlled exchange of introduced between the rotating and stationary system components purge gas. To maintain a certain exchange of purge gas, it applies this at least proportionally via corresponding connection channels or leakage-related ring seal assemblies radially outwards, usually discharge into the working channel of the respective flow rotary machine. In the case of a turbine stage thus the purge gas passes through corresponding intermediate gaps in the hot gas channel, in which the purge gas mixed with the hot gases.

In addition to the already explained flow irritation, which exerts the purge gas flow due to leakage to the cooling air flow passing substantially axially through the annulus, the high swirl content of the purge gas flow also contributes to reducing the static pressure within the annulus, which in turn reduces the cooling effect of the cooling air flow in the rotor unit and the associated blades is weakened.

From the GB2081392 For example, a stator assembly of a turbomachine is known that includes sealing disks that cooperate with sealing elements on an adjacent rotor assembly.

From the GB2251040 Furthermore, a sealing arrangement for a seal between a rotating and stationary part is known, in which a rotating sealing arm has bores through which a leakage due to the back pressure on the rotating arm is fed back against the pressure gradient.

Presentation of the invention

The invention is based on the object of a gas turbine arrangement and a method for operating a gas turbine arrangement with a rotatable about a rotor axis rotor unit and at least one stationary component axially limited annular space in which open from the at least one stationary component a plurality of coolant outlet openings, from which in each case a coolant flow, preferably in the form of a cooling air flow, can be brought into the annular space, which at least partially passes into coolant inlet openings, which are provided in the flow direction of the coolant flow propagating through the annular space in the rotor unit, and at least one radially to the annular space, of the rotor unit and at least one stationary component limited cavity, which is pressurized with a purge gas and fluidly connected to the annulus, so educate, that in the annulus system inherent purge gas flow has a negligible disturbance low on the annulus largely axially passing coolant flow. In particular, it is necessary to take measures by which the pressure conditions within the annular space remain as uninfluenced, despite a purge gas flow entering the annulus.

The solution of the problem underlying the invention is specified in claim 1. A solution-based method for operating a gas turbine arrangement is specified in claim 10. The concept of the invention advantageously further features are the subject of the dependent claims and the further description with reference to the exemplary embodiments.

According to the solution, a gas turbine arrangement having the features of the preamble of claim 1 is formed in that the at least one stationary component and the rotor unit include a gap space through which the at least one cavity is separated from the radially outer annular space and via which the at least one cavity with the radially outer annular space is fluidly connected, and that protrude into the gap space on one side of the at least one stationary component fixed flow guide.

The formation and arrangement of the flow-guiding along the at least one stationary component are made such that the pressurized purge gas passes through the gap in the direction of the annular space due to a pressure gradient existing between the at least one cavity and the annulus in the form of a purge gas flow, so that the purge gas upon passage through the gap, a largely vortex-free flow characteristic is impressed, ie, that of the purge gas flow Passage through the gap in the annulus inherent Strömungsdrallanteil is considerably smaller than the initial flow swirl of the purge gas before passing through the gap, ie within the at least one cavity. The aim is to reduce the swirl, which is imparted to the purge gas stream in the cavity by rotation of the rotor unit in the direction of rotation of the rotor unit. In one embodiment, purge gas flow will flow without swirl about the rotor axis from the gap space into the annulus. It is desirable to smooth out as far as possible the purging gas flow strongly swirling on the cavity side as it passes through the gap, ie, ideally, the purging gas flow should pass the annulus free of eddies, ie in the form of a laminar flow. A vortex-free or vortex-free purge gas flow passing through the annulus has, on the one hand, a low disruption potential for the largely axially directed cooling air flow, and on the other hand, the static pressure inside the annulus is not adversely affected.

In order to ensure a controlled outflow of the flushing gas located in the at least one rotor axis, the at least one cavity adjoins the annular space directly or indirectly radially to the rotor axis via a gap-shaped constriction. Due to the largely axisymmetric design of the rotor unit and the rotor unit immediately adjacent arranged, stationary components of the gas turbine assembly includes the gap-shaped constriction between the rotor unit and the at least one stationary component an annular gap-shaped gap through which a purge gas flow due to a between the at least one cavity and the annular space existing radial pressure gradient forms.

In the circumferential direction of the ring, on the side of the stationary component, which delimits the gap space on one side, a plurality of individual flow directing means is provided, which extend into the gap space without coming into contact with the rotor unit. The in the ring circumferential direction, preferably with equidistant distance attached flow guide each limit in pairs a flow area, the flow path for the out of the at least one Cavity leaking purge gas determined in the direction of the radially outer annular space. For the arrangement and design of the individual flow guide, it is important to take into account the fact that the purge gas strongly swirling within the cavity passes the annular space in the further radially outward direction, if possible in the form of a vortex-reduced, preferably vortex-free purge gas flow. In a preferred embodiment, the flow guide means are formed in the form and shape of vanes having a blade profile curved in the axial direction. An axially curved blade profile forms at its upstream end (inflow edge) an entry angle between the profile and rotor axis, which in the direction of rotation of the rotor and at its downstream end (discharge edge) an exit angle between the profile and rotor axis, which is smaller than the entry angle. Typically, the exit angle is zero. The angle may even point against the circumferential direction of the rotor rotation to produce a slight counter-rotation. This can be advantageous, for example, to obtain a total swirl-free flow after mixing with the part of the scavenging air, which does not flow through between the blade profiles, but flows through in the gap between the profile end and the rotor unit.

According to one embodiment, the flow-guiding means are variably adjustable around at least one spatial axis.

Of course, deviating Strömungsleitmittel are also conceivable here, for example in the form of rectilinearly formed flow stable ribs, which are distributed to the above explanations each with equidistant spacing to each other in the circumferential direction fixed to the at least one stationary component and projecting unilaterally freely ending in the gap.

Brief description of the invention

Fig. 1a

Längsschnitt durch eine schematisierte Darstellung des zwischen Rotoreinheit und stationärer Komponente begrenzten Spaltraums,

Fig. 1b

schematisierte Anordnung von Strömungsleitmitteln an der stationären Komponente in axialer Sichtweise,

Fig. 1c

mit der stationären Komponente verbundene Strömungsleitmittel in radialer, nach außen orientierter Sichtweise, sowie

Fig. 1 d

schematisierte Anordnung von Strömungsleitmitteln an der stationären Komponente in axialer Sichtweise.

The invention will now be described by way of example without limitation of the general inventive idea by means of embodiments with reference to the drawing. Show it:

Fig. 1a

Longitudinal section through a schematic representation of the space defined between rotor unit and stationary component gap space,

Fig. 1b

schematized arrangement of flow guiding means on the stationary component in axial view,

Fig. 1c

connected to the stationary component flow guide in a radial, outwardly oriented view, as well

Fig. 1 d

schematic arrangement of Strömungsleitmitteln on the stationary component in the axial view.

Ways to carry out the invention, industrial usability

Fig. 1a shows a longitudinal section through a portion of a gas turbine plant, which schematically shows a portion of the rotor unit 2, which is rotatably arranged about the rotor axis A. It is assumed that the in 1a illustrated rotor unit 2 corresponds to one of the first turbine blade row assignable rotor disk, at the peripheral edge of the turbine blades T are arranged.

The rotor unit 2 axially opposite a stationary component 1 is provided, on whose surface facing the rotor unit 2 a plurality of individual coolant outlet openings 4 is provided, from the cooling air K, usually in the form of a suitably predetermined Draliströmung, in between the rotor unit 2 and the stationary component 1 on both sides limited annular space 5 is discharged. Within the stationary component 1, a cooling air reservoir is introduced, which is supplied via a cooling air system with cooling air. A corresponding nozzle arrangement within the respective cooling air outlet openings 4 provides a flow twist along the inflowing into the annulus 5 cooling air flow K.

Depending on the design of the coolant inlet opening, it may be advantageous to introduce the cooling air K into the annulus 5 without twisting. In this case, the respective cooling air outlet openings 4 are arranged so that the cooling air is swirl-free, i. is introduced axially into the annular space 5.

Preferably, the swirl of the cooling air K and scavenging air K is the same when they are mixed in order to minimize the mixing losses.

Radially outwards, that is to say for the hot gas duct leading the hot gases H, the illustrated annular space 5 is at least partially closed off by platform ends of a series of guide vanes L.

A portion of the introduced into the annulus 5 cooling air flow K passes through rotor provided on the coolant inlet openings 3 in the interior of the rotor unit 2, in the corresponding cooling lines (not shown) are provided, which forward the absorbed cooling air K preferably in the areas of the turbine blades T. For an effective cooling of the rotor unit 2 and in particular of the turbine blades T, it is important not to impair the pressure and flow conditions within the annular space 5, so that it is ensured that sufficient amount of cooling air K from the stationary component 1 via the annulus 5 in the Rotor unit 2 can get.

In contrast, include rotor unit 2 and the stationary component 1 and optionally other stationary components 1 * a near-rotor cavity 7, which is filled with purge gas to protect radially inner rotor areas and adjacent stationary components from overheating.

For a replacement of the introduced in the cavity 7 purge gas usually enters a part of the purge gas in the form of a purge gas flow S through a between the rotor unit 2 and the stationary component 1 on both sides limited gap space 6 in the annular space 5, the purge gas flow S substantially transversely to the cooling air flow K passes radially outward and ultimately the hot gases H is mixed in the working channel of the gas turbine arrangement. Depending on the choice of pressure conditions between annulus and hot gas channel, it may also come to a slight end-ring of hot gas in the annulus.

In order to prevent the annular space 5 radially outwardly passing purge gas flow S, which is strongly swirled due to the rotational movements of the rotor unit 2 in the region of the cavity 7 and thus reduce both the pressure conditions in the annulus 5 and would significantly disturb the cooling air flow K are attached to the stationary component 1 in the region of the gap space 6 6 Strömungsleitmittel, each unilaterally free-end into the gap 6 protrude. The individual flow guiding means 8 are designed in the form of small guide vanes and protrude from the sides of the stationary component 1 on one side into the gap space 6, without touching the rotor unit 2.

Depending on the choice of the narrow gap 6 ', the height of which should ideally approach zero, transient operation of the gas turbine may cause the flow-guiding means 8 to rub against the rotor unit 2. In order to permit such rubbing, an abrasive edge, a cutting edge or equivalent means may be provided at the free end of the flow directing means 8. Furthermore, the use of honeycombs or an abrasion layer on the corresponding rubbing surface of the rotor unit 2 is possible.

In Fig. 1b is an illustration with an axial view of the gap space 6 (section AA of FIG. 1 a) shown limited between the stationary component 1 and the rotor unit 2. You can see the coolant outlet openings 4, from which cooling air is discharged from the side of the stationary component 1 in the annulus. Fixed to the stationary component 1, respectively, flow-guiding means 8 are connected on one side, which project into the gap 6 and thus the gap space 6 in a plurality of between the flow-guiding limited flow areas D divided. The individual flow guiding means 8, which are preferably designed in the form of small guide vanes, have at their free end, which faces the rotor unit 2, in each case a shroud 8 ', which encloses a narrow gap 6' with the rotor unit 2. The gap width of the narrow gap 6 'should be less than half the gap width d of the gap space 6. Preferably, however, the narrow gap 6 'should be set so low, so that as possible no flow components of the purge gas flow S can pass through the between the shrouds 8' of the flow guide 8 and the rotor unit 2.

In order to smooth the strongly swirling purge gas flow S, as it exits directly from the cavity 7 in the direction of the annulus 5, with respect to their vortex, the flow areas D between each adjacently arranged Strömungsleitmittel 8 serve as forced flow paths, along which the purge gas flow S smoothed, homogenized or is made uniform, so that flows downstream of the flow guide 8 a largely vortex-free and in a uniform flow direction propagating purge gas flow into the annulus 5.

Fig. 1c shows a radially outwardly oriented view of the profile of the respective flow guide 8 (section BB). The individual flow-guiding means 8 likewise include curved flow-through regions D, which are curved in the axial direction so that they flow through the purge gas flow.
The shape and design of the Strömungsleitmittel can be adjusted individually depending on the aerodynamic Spülgascharakteristik within the cavity 7 and is not limited to the formation as a vane-like profile shapes.

It would also be possible to vary the arrangement or the position of the individual flow-guiding means relative to the purge-gas flow S flowing through the flow-through regions D in order to adjust, if necessary, as a function of different load stages Gas turbine plant, where different degrees of turbulence within the purge gas can form in the cavity 7 to make.

In Fig. 1d is a representation of a second embodiment with axial viewing direction of the gap space 6 (section AA) shown. This differs from the one in Fig. 1b in order to minimize the leakage through the narrow gap 6 ', a seal 9 is mounted on the shroud 8 ". This may be at least one sealing strip of a labyrinth seal or, for example, a brush seal. Similarly, the seal may also be attached to the rotor unit 2.

In one embodiment, the flow directors 8 are assembled as segments with the closed shroud 8 ", for example, a plurality of flow directors 8 are provided as a circular section with the shroud 8" closed.

LIST OF REFERENCE NUMBERS

1

Stationary component

1*

Stationary component

2

rotor unit

3

Coolant inlet openings

4

Coolant outlet openings

5

annulus

6

gap

6 '

narrow gap

7

cavity

8th

flow guide

8th'

shroud

8th"

Closed shroud

9

poetry

A

rotor axis

D

Flow channel

H

hot gases

K

Coolant flow

L

vane

S

purge gas

d

Gap width of the gap

Claims (10)

1. Gas turbine arrangement having an annulus (5), which is axially delimited between a rotor unit (2), which is rotatable around a rotor axis (A), and at least one stationary component (1), into which annulus, from the at least one stationary component (1), lead a multiplicity of cooling medium outlet openings (4) from which a cooling medium flow (K) can be discharged in each case into the annulus (5), which cooling medium flow finds its way at least proportionately into cooling medium inlet openings (3) which are provided in the rotor unit (2) in the flow direction of the cooling medium flow (K) which propagates through the annulus (5), and also having, radially to the annulus (5), at least one inner cavity (7) which is delimited by the rotor unit (2) and by the at least one stationary component (1*), is pressurized with a purging gas (S), and is fluidically connected to the annulus (5), wherein the at least one stationary component (1) and the rotor unit (2) include a constriction (6) by means of which the at least one cavity (7) is separated from the radially outer annulus (5) and via which the at least one cavity (7) is fluidically connected to the radially outer annulus (5), characterized in that flow guiding means (8), which are fastened on the at least one stationary component (1) on one side, project into the constriction (6).
2. Gas turbine arrangement according to Claim 1,
   characterized in that the constriction (6) is formed at least in sections in an annular manner between the at least one stationary component (1) and the rotor unit (2), and
   in that a multiplicity of flow guiding means (8), distributed in the circumferential direction, are provided along the annular constriction (6) so that two adjacent flow guiding means (8) delimit a throughflow section (D) in each case.
3. Gas turbine arrangement according to Claim 1 or 2,
   characterized in that the flow guiding means (8) are formed in such a way that a purging gas flow (S), which through the constriction (6) from the at least one cavity (7) enters the annulus (5), obtains a flow characteristic which is applied by means of the flow guiding means (8).
4. Gas turbine arrangement according to one of Claims 1 to 3,
   characterized in that the flow guiding means (8) are formed in the style of guide vanes.
5. Gas turbine arrangement according to Claim 4,
   characterized in that the guide vanes have in each case a blade profile which is curved in the axial direction.
6. Gas turbine arrangement according to one of Claims 1 to 5,
   characterized in that the flow guiding means (8) have in each case a free end which faces the rotor unit (2) and together with the rotor unit (2) include a narrow gap (6'), the gap width of which is less than or equal to half the gap width d of the constriction (6), i.e. less than or equal to half the largest distance between the at least one stationary component (1) and the rotor unit (2) in the region of the constriction (6).
7. Gas turbine arrangement according to one of Claims 4 to 6,
   characterized in that the flow guiding means (8) in the form of guide vanes have in each case a shroud (8') attached on the free end.
8. Gas turbine arrangement according to one of Claims 1 to 7,
   characterized in that the rotor unit (2) is a rotor disk with turbine rotor blades attached on its circumferential edge, and in that the at least one stationary component (1) is a stationary component (1) which is attached directly axially opposite the rotor unit, with a cooling air reservoir which can be supplied with cooling air (K) by means of a cooling air system and from which cooling air (K) finds its way into the annulus (5) via the cooling medium outlet openings (4).
9. Gas turbine arrangement according to one of Claims 1 to 8,
   characterized in that the flow guiding means are variably adjustable around at least one spatial axis.
10. Method for operating a gas turbine arrangement having an annulus (5), which is axially delimited between a rotor unit (2), which is rotatable around a rotor axis (A), and at least one stationary component (1), into which annulus, from the at least one stationary component (1), lead a multiplicity of cooling medium outlet openings (4) from which a cooling medium flow (K) can be discharged in each case into the annulus (5), which cooling medium flow finds its way at least proportionately into cooling medium inlet openings (3) which are provided in the rotor unit (2) in the flow direction of the cooling medium flow (K) which propagates through the annulus (5), and also having, radially to the annulus (5), at least one inner cavity (7) which is delimited by the rotor unit (2) and by the at least one stationary component (1*), is pressurized with a purging gas (S), and is fluidically connected to the annulus (5),
    wherein the pressurized purging gas (S), on account of a pressure drop which exists between the at least one cavity (7) and the annulus (5), passes in the form of a purging gas flow (S) through a constriction (6) by means of which the at least one cavity (7) is separated from the radially outer annulus (5) and via which the at least one cavity (7) is fluidically connected to the radially outer annulus (5), characterized in that a swirl of the purging gas flow (S) is reduced when passing through the constriction (6) by means of flow guiding means (8) which are provided inside the constriction (6).

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