Turbomachine and method for disassembling such a turbomachine

Abstract

A turbine includes an outer casing and an inner casing surrounded by said outer casing. The outer casing and inner casing are coaxially arranged with respect to a machine axis. The outer casing and inner casing are each divided in a split plane into an upper part and a lower part. The upper and lower parts are connected with each other in said split plane by means of a flanged connection. The disassembly process is improved by the flanged connection of the upper and lower part of the inner casing comprising a plurality of bolts, which extend each through through holes in respective flanges of said flanged connection of the inner casing, protrude from said through holes at both ends with a threaded section, and are tightened by means of nuts screwed on said threaded sections at both ends of said bolt.

Claims

1. A turbomachine configured to include an inner casing mounted to an outer casing when fully assembled, wherein in a state of disassembly the turbomachine comprising: said inner casing having an upper part and a lower part with a first flanged connection including a first through hole, the upper part and lower part of the inner casing bearing a plurality of vanes; a guide ring having a second flanged connection with a second through hole, wherein the first flanged connection of said inner casing is connected to the second flanged connection of the guide ring; a plurality of bolts extending each through the first and second through holes in said first and second flanged connections respectively, wherein each bolt has threaded sections that protrude from the first and second flanged connections on each end and a shank that fully extends through said through holes such that the threaded sections protrude from said through holes, wherein said bolts are provided with screw heads at each end for rotationally fixing said bolts during disassembly; and a pair of nuts secure each bolt to the first and second flanged connections via the threaded sections, wherein each nut in combination with a respective screw head provides means for disassembling the first and second flange connections, such that a rotationally fixed screw head allows untightening of at least one nut of the pair of nuts.

2. The turbomachine according to claim 1, further comprising washers disposed between each nut and the first and second flanged connections.

3. The turbomachine according to claim 2, wherein said bolts are designed as waisted shank bolts.

4. A method for disassembling a turbomachine including an inner casing having an upper part and a lower part divided in a split plane with a first flanged connection including a first through hole, the upper part and lower part of the inner casing bearing a plurality of vanes; a guide ring having a second flanged connection with a second through hole, wherein the first flanged connection of said inner casing is connected to the second flanged connection of the guide ring; a plurality of bolts extending each through the first and second through holes in said first and second flanged connections respectively, wherein each bolt has threaded sections that protrude from the first and second flanged connections on each end and a shank that fully extends through said through holes such that the threaded sections protrude from said through holes, wherein said bolts are provided with screw heads at each end for rotationally fixing said bolts during disassembly; and a pair of nuts secure each bolt to the first and second flanged connections via the threaded sections, wherein each nut in combination with a respective screw head provides means for disassembling the first and second flanged connections, such that a rotationally fixed screw head allows untightening of at least one nut of the pair of nuts, wherein when fully assembled an outer casing and said inner casing are coaxially arranged with respect to a machine axis, said outer casing is divided in the split plane into an upper part and a lower part, the method comprising: demounting the upper part of the outer housing; untightening the bolts of the first flanged connection of the inner casing at respective upper part ends by unscrewing respective nuts; removing the upper part of the inner casing; mounting the guide ring on the lower part of the inner casing to replace the upper part of the inner casing; tightening the bolts of the first flanged connection of the inner casing at upper part ends to connect the second flanged connection of the guide ring to the lower part of the inner casing; rotating an assembly of the lower part of the inner casing and the guide ring by 180° around the machine axis; untightening the bolts of the first flanged connection of the inner casing at lower part ends by rotationally fixing each bolt via a respective screw head and unscrewing the respective nuts; and removing the lower part of the inner casing.

5. The turbomachine according to claim 1, wherein the first flanged connection of the inner casing is thicker than the second flanged connection of the guide ring.

6. The turbomachine according to claim 2, wherein the washers are disposed in a recess of the second flanged connection.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The present invention is now to be explained more closely by means of different embodiments and with reference to the attached drawings.

(2) FIG. 1 shows a series of steps during a well-known process of disassembling a gas turbine with split inner and outer casings;

(3) FIG. 2 shows in a perspective view a bolt for the flange connection of the inner casing according to an embodiment of the invention;

(4) FIG. 3 shows the flange connection between the lower part of the inner casing and a mounted guide ring, which is used for the disassembling process according to FIG. 1, according to an embodiment of the invention; and

(5) FIG. 4 shows the configuration of FIG. 3 after a rotation by 180° of the inner casing part around the machine axis.

DETAILED DESCRIPTION

(6) FIG. 3 shows in a cross section the flange connection according to an embodiment of the invention, between the lower part 12b of the inner casing 12 and mounted guide ring 17, which flange connection is used for the disassembling process according to FIG. 1. Guide ring 17 has a flange 23 with a through hole 24, which is similar to the flange of the already removed upper part 12a of inner casing 12. Lower part 12b of inner casing 12 has a flange 25 with a through hole 26. The thickness of flange 25 can be and is reduced as there is no need to provide a threaded hole for fastening a bolt.

(7) The flange connection between lower part 12b of inner casing 12 and guide ring 17 comprises a plurality of bolts 18, which extend each through through holes 24 in flange 23, and through holes 26 in flange 25. The bolts 18, which are designed as waisted shank bolts, as shown in FIG. 2, protrude from said through holes 24 and 26 at both ends with a threaded section 18b and 18d, and are tightened by means of nuts 19 and 22 screwed on said threaded sections 18b and 18d at both ends of said bolts 18.

(8) Especially, washers 20 and 21 are provided between each nut 19 and 22 and the respective flange 23 and 25.

(9) According to FIG. 2, bolts 18 are designed as waisted shank bolts with a waisted shank 18a in the middle and threaded sections 18b and 18d at both ends. Screw heads 18c and 18e may be provide in order to rotationally fix the bolt during untightening action.

(10) When the arrangement of lower part 12b of inner casing 12 and guide ring 17 has been rotated by 180°, as shown in FIG. 4, upper nut 22 can easily be unscrewed and lower part 12b can be removed without using special tools.

(11) The invention thus uses waisted shank bolts with threads and nuts on both ends to improve the disassembling process of the turbine.

(12) The use of waisted shank bolts is advantageous for the corresponding flange design of the casings, which allows slimmer flanges, thus ensuring less ovalisation of inner casings during engine operation. The existing flange design with a thread inside one of the flange halves, on the other hand, requires a thick flange design in order to ensure a required clamping length.

(13) Compared to the solution disclosed in document EP 2 213 846 A1, no special tooling is required.