Stationary gas turbine arrangement and method for performing maintenance work

1. A stationary gas turbine engine with at least one turbine stage, the engine comprising:

at least a first row of vanes being mounted at a stationary component arranged radially outside of the first row of vanes and extending radially into an annular entrance opening of an inner component of the turbine stage facing a downstream end of a combustor, wherein the stationary component provides for each vane a radially orientated through-hole designed and arranged for a radial insertion and removal of the vane, and each of said vanes including an airfoil having at its one end directed radially outwards a contour being adapted to close the through-hole airtight by a detachable fixation, wherein the airfoil of each of the vanes includes at an end directed radially inwards an extension for inserting into a recess of an inner platform, wherein the inner platform is detachably mounted to an intermediate piece which is detachably mounted to the inner component of the turbine stage, wherein the intermediate piece provides at least one recess for insertion of a hook like extension of the inner platform for axially, radially and circumferential fixation of the inner platform, the intermediate piece comprising a labyrinth sealing with respect to the inner component of the turbine stage.

2. The stationary gas turbine engine according to claim 1 , wherein the through-hole in the stationary component is of a shape of a largest cross-section of the airfoil of the vane, or the through-hole in the stationary component is of a shape for insertion an outer platform being connected to the outer end of the airfoil directed radially outwards.

3. The stationary gas turbine engine according to claim 1 , wherein said inner platform provides at least one recess for insertion of the extension, being hook like in shape, of at least one airfoil, so that the airfoil is detachable fixed at least in axial and circumferential direction of the turbine stage and radially movable within the recess.

4. The stationary gas turbine engine according to claim 1 , wherein the turbine stage is encapsulated by a casing in which at least one manhole is provided, and that inside the casing there is enough space for a worker to mount and/or demount at least one vane by radially insertion and/or removal the airfoil through the through-hole of the stationary component.

5. A method for mounting and demounting at least an airfoil of a vane, an inner platform, and an intermediate piece according to claim 1 , comprising:

gaining access to the detachable fixation of airfoils of the first row of vanes by entering a casing encapsulating the turbine stage through a manhole inside the casing;

removing the detachable fixation; and

removing the airfoil in radial direction through the through-hole.

6. The method according to claim 5 , comprising:

reassembling the stationary gas turbine engine by performing each step of the method in a reverse order.

7. A stationary gas turbine engine with at least one turbine stage, the engine comprising:

at least a first row of vanes being mounted at a stationary component arranged radially outside of the first row of vanes and extending radially into an annular entrance opening of an inner component the turbine stage facing a downstream end of a combustor, wherein the stationary component provides for each vane a radially orientated through-hole designed and arranged for a radial insertion and removal of the vane, and each of said vanes including an airfoil having at its one end directed radially outwards a contour being adapted to close the through-hole airtight by a detachable fixation, wherein the airfoil of each of the vanes includes at an end directed radially inwards an extension for inserting into a recess of an inner platform, wherein the inner platform is detachably mounted to an intermediate piece which is detachably mounted to an inner component of the turbine stage, wherein the intermediate piece provides at least one recess for insertion of a hook like extension of the inner platform for axially, radially and circumferential fixation of the inner platform; and

wherein the intermediate piece provides two separates recesses for insertion of hooks of the inner platform, wherein each recess provides an axial groove having a T-cross section, and wherein each of the hook like extensions having a T-shaped contour for mounting in the intermediate piece.

8. A method for performing maintenance work on a stationary gas turbine engine comprising at least a first row of vanes being mounted at a stationary component arranged radially outside of the first row of vanes and extending radially into an annular entrance opening of an inner component the turbine stage facing a downstream end of a combustor, wherein the stationary component provides for each vane a radially orientated through-hole designed and arranged for a radial insertion and removal of the vane, and each of said vanes including an airfoil having at its one end directed radially outwards a contour being adapted to close the through-hole airtight by a detachable fixation, wherein the airfoil of each of the vanes includes at an end directed radially inwards an extension for inserting into a recess of an inner platform, wherein the inner platform is detachably mounted to an intermediate piece which is detachably mounted to an inner component of the turbine stage, wherein the intermediate piece provides at least one recess for insertion of a hook like extension of the inner platform for axially, radially and circumferential fixation of the inner platform, the method comprising:

gaining access to the detachable fixation of the airfoil of the first row of vanes by entering a casing encapsulating the turbine stage through a manhole inside the casing;

removing the detachable fixation;

removing the airfoil in radial direction through the through-hole;

gaining access to the inner platform by entering the combustor through a further manhole; and

removing the inner platform.

9. The method according to claim 8 , wherein removing said inner platform is performed by pressing the inner platform radially inwards, moving the inner platform in direction to the combustor and tilting the inner platform for separation.

10. The method according to claim 8 , further comprising:

removing the intermediate piece for getting access to the first stage blade.

11. The method according to claim 8 , comprising:

reassembling the stationary gas turbine engine by performing each step of the method in a reverse order.