STEAM TURBINE AND METHOD FOR OPERATING A STEAM TURBINE

Abstract

A steam turbine having a cooling option, in which steam is taken from the flow channel, the steam cooling the thrust-compensating intermediate floor, being mixed with a small amount of live steam and being returned to the flow channel. A method cools the steam turbine, wherein steam is extracted from the high-pressure region and is fed to a space between the thrust-compensating partition wall and inner casing, wherein steam from the space between the thrust-compensating partition wall and the inner casing is fed via a first cross feedback passage to the high-pressure region.

Claims

1. A steam turbine comprising: an inner casing and an outer casing and also a rotor which is arranged in a rotatably supported manner inside the inner casing, wherein the outer casing is arranged around the inner casing, wherein the rotor has a high-pressure region which is arranged along a first flow direction and an intermediate-pressure region which is arranged along a second flow direction, wherein the inner casing has a plurality of high-pressure stator blades in the high-pressure region, which are arranged in such a way that a high-pressure flow passage, having a plurality of high-pressure blading stages which in each case have a row of high-pressure rotor blades and a row of high-pressure stator blades, is formed along the first flow direction, wherein the inner casing has a plurality of intermediate-pressure stator blades in the intermediate-pressure region, which are arranged in such a way that an intermediate-pressure flow passage, having a plurality of intermediate-pressure blading stages which in each case have a row of intermediate-pressure rotor blades and a row of intermediate-pressure stator blades, is formed along the second flow direction, wherein the rotor has a thrust-compensating partition wall between the high-pressure region and the intermediate-pressure region, wherein the inner casing has a connection which, as a communicating pipe, is formed between the high-pressure flow passage, downstream of a first high-pressure blading stage, and a first thrust-compensating partition wall space, wherein the inner casing has a first cross feedback passage which, as a communicating pipe, is formed between a second thrust-compensating partition wall space, which is arranged between the thrust-compensating partition wall and the inner casing, and a high-pressure inflow space, in the high-pressure flow passage, which is arranged downstream of a second high-pressure blading stage.

2. The steam turbine as claimed in claim 1, wherein the first high-pressure blading stage is arranged upstream of the second high-pressure blading stage as seen along the first flow direction.

3. The steam turbine as claimed in claim 1, wherein the first thrust-compensating partition wall space is arranged upstream of the second thrust-compensating partition wall space as seen along the first flow direction.

4. The steam turbine as claimed in claim 1, wherein between the inner casing and the thrust-compensating partition wall a first brush seal is arranged upstream of the second thrust-compensating partition wall space along the second flow direction and a second brush seal is arranged downstream of the first thrust-compensating partition wall space along the second flow direction.

5. The steam turbine as claimed in claim 1, wherein the first cross feedback passage is formed by pipes.

6. The steam turbine as claimed in claim 1, wherein the connection is formed by connecting pipes.

7. The steam turbine as claimed in claim 1, further comprising: a second cross feedback passage which, as communicating pipe, is formed between a third thrust-compensating partition wall space, which is arranged between the thrust-compensating partition wall and the inner casing, and a high-pressure inflow space, in the high-pressure flow passage, which is arranged downstream of a third high-pressure blading stage.

8. The steam turbine as claimed in claim 1, wherein the third high-pressure blading stage is arranged downstream of the second high-pressure blading stage as seen in the first flow direction.

9. A method for cooling a steam turbine, wherein the steam turbine has a high-pressure region and an intermediate-pressure region, wherein a rotor has a thrust-compensating partition wall between the high-pressure region and the intermediate-pressure region, the method comprising: extracting steam from the high-pressure region and feeding to a space between the thrust-compensating partition wall and inner casing, feeding steam from the space between the thrust-compensating partition wall and the inner casing via a first cross feedback passage to the high-pressure region.

10. The method as claimed in claim 9, further comprising: between thrust-compensating partition wall and inner casing, feeding additional steam via a second cross feedback passage into the high-pressure region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In the drawing:

[0033] FIG. 1 shows a schematic cross-sectional view of a steam turbine,

[0034] FIG. 2 shows a detail of the steam turbine shown in FIG. 1 with the arrangement according to the invention.

DETAILED DESCRIPTION OF INVENTION

[0035] FIG. 1 shows a steam turbine 1 comprising an inner casing 2 and an outer casing 3 and also a rotor 4. The rotor 4 is arranged in a rotatably supported manner inside the inner casing 2. The bearing arrangement is not shown in more detail. The outer casing 3 is arranged around the inner casing 2. The rotor 4 is designed in the main rotationally symmetrically around the rotational axis 5. Along a first flow direction 6, which extends generally parallel to the rotational axis 5, the rotor 4 has a high-pressure region 7. Arranged opposite to the first flow direction 6, the rotor 4 has an intermediate-pressure region 9 which is arranged along the second flow direction 8.

[0036] In the high-pressure region 7, the inner casing 2 has a plurality of high-pressure stator blades (not shown) which are arranged on the circumference around the rotational axis 5. The high-pressure stator blades are arranged in such a way that a high-pressure flow passage 10, having a plurality of high-pressure blading stages (not shown) which in each case have a row of high-pressure rotor blades and a row of high-pressure stator blades, is formed along the first flow direction 6.

[0037] Via a first high-pressure inflow region 11, live steam flows into the steam turbine 1 and then flows through the high-pressure flow passage 10. The steam expands in the high-pressure flow passage 10, wherein the temperature drops. The thermal energy of the steam is converted into rotational energy of the rotor 4. After the steam has flown through the high-pressure flow passage 10, it flows onward out of the steam turbine 1 from a high-pressure outflow region 12 to a reheater (not shown in more detail). In the reheater, the cooled steam is again brought up to a high temperature which is comparable to the live steam temperature in the high-pressure inflow region. However, the pressure in the inflow region 11 is appreciably lower.

[0038] In the intermediate-pressure region 9, the inner casing 2 has a plurality of intermediate-pressure stator blades (not shown) which are arranged in such a way that an intermediate-pressure flow passage 13, having a plurality of intermediate-pressure blading stages (not shown) which in each case have a row of intermediate-pressure rotor blades and a row of intermediate-pressure stator blades, is formed along the second flow direction 8.

[0039] Downstream of the reheater, the steam flows via the intermediate-pressure inflow region 14 through the intermediate-pressure flow passage 13. The thermal energy of the steam is converted into rotational energy of the rotor 4. Downstream of the intermediate-pressure flow passage 13, the steam flows out of the turbine 1 via an outlet 15. The steam is then directed further to a low-pressure turbine section (not shown) or to a process as process steam. The rotor 4 has a thrust-compensating partition wall 16 between the high-pressure flow passage 10 and the intermediate-pressure flow passage 13.

[0040] This thrust-compensating partition wall 16 has a larger diameter than the rotor 4.

[0041] The live steam temperature lies at 530° C.-720° C. at a pressure of 80 bar-350 bar. The intermediate-pressure temperature lies at 530° C.-750° C. at a pressure of 30 bar-120 bar.

[0042] FIG. 2 shows a detail of the steam turbine 1 from FIG. 1, wherein further features according to the invention are shown in FIG. 2. The inner casing 2 has a connection 17 which, as communicating pipe, is arranged between the high-pressure flow passage 10, downstream of a first high-pressure blading stage 18, and a first thrust-compensating partition wall space 19, wherein the thrust-compensating partition wall space 19 is arranged between the thrust-compensating partition wall 16 and the inner casing 2. The inner casing 2 has a plurality of segments 20 in the region of the thrust-compensating partition wall 16. The segments 20 in each case have a labyrinth seal (not shown).

[0043] The inner casing 2 furthermore has a first cross feedback passage 21 which, as a communicating pipe, is arranged between a second thrust-compensating partition wall space 22 (which is arranged between the thrust-compensating partition wall 16 and the inner casing 2) and a second high-pressure blading stage 23.

[0044] The first high-pressure blading stage 18 is arranged upstream of the second high-pressure blading stage 23 as seen along the first flow direction 6.

[0045] The first thrust-compensating partition wall space 19 is arranged upstream of the second thrust-compensating partition wall space 22 as seen along the first flow direction 6.

[0046] Between the inner casing 2 and the thrust-compensating partition wall 16 a first brush seal 24 is arranged upstream of the second thrust-compensating partition wall space 22 along the second flow direction 8.

[0047] A second brush seal 25 is arranged downstream of the first thrust-compensating partition wall space 19 along the second flow direction 8.

[0048] The first cross feedback passage 21 can be formed by pipes (not shown) in alternative embodiments. In the exemplary embodiment shown in FIG. 2 the cross feedback passage 21 is arranged in the inner casing 2.

[0049] The connection 17 is formed in the inner casing 2 in the exemplary embodiment selected in FIG. 2 and in alternative embodiments the connection 17 can be formed by connecting pipes.

[0050] The steam turbine 1 has a second cross feedback passage 26 which, as communicating pipe, is formed between a third thrust-compensating partition wall space 27, which is arranged between the thrust-compensating partition wall 16 and the inner casing 2, and a high-pressure inflow space, which is arranged downstream of a third high-pressure blading stage 28, in the high-pressure flow passage 10.

[0051] The third high-pressure blading stage 28 is arranged downstream of the second high-pressure blading stage 23 as seen in the first flow direction 6. The cross feedback passage 26 can be formed in the inner casing 20. In alternative embodiments, the third cross feedback passage 26 can be formed as a pipe.

[0052] Although the invention has been described and fully illustrated in detail by means of the preferred exemplary embodiment, the invention is therefore not limited by the disclosed examples and other variations can be derived by the person skilled in the art without departing from the scope of protection of the patent.