EP3610137A1

EP3610137A1 - Steam turbine and method for operating same

Info

Publication number: EP3610137A1
Application number: EP18708060.1A
Authority: EP
Inventors: Bernd Leidinger; Stefan PREIBISCH; Stefanie Ruhsland
Original assignee: Siemens AG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2017-07-03
Filing date: 2018-02-14
Publication date: 2020-02-19
Anticipated expiration: 2038-02-14
Also published as: US20210156283A1; RU2735461C1; DE102017211295A1; JP6980043B2; PL3610137T3; JP2020525704A; EP3610137B1; US11352910B2; WO2019007557A1; BR112019026024A2; CN110832169B; BR112019026024A8; CN110832169A

Abstract

The invention relates to a steam turbine (1a; b), comprising: a steam turbine outer housing (20); a high-pressure inner housing (30) having a first process steam inlet section (31) and a first process steam outlet section (32) for conducting process steam through the high-pressure inner housing (30) from the first process steam inlet section (31) to the first process steam outlet section (32) in a first process steam expansion direction (33); a low-pressure inner housing (40) having a second process steam inlet section (41) and a second process steam outlet section (42) for conducting process steam through the low-pressure inner housing (40) from the second process steam inlet section (41) to the second process steam outlet section (42) in a second process steam expansion direction (43); and an intermediate superheater (50), which is arranged downstream of the high-pressure inner housing (30) and upstream of the low-pressure inner housing (40), wherein the high-pressure inner housing (30) and the low-pressure inner housing (40) are arranged within the steam turbine outer housing (20) and the high-pressure inner housing (30) and the low-pressure inner housing (40) are arranged in such a way that the first steam inlet section (31) of the high-pressure inner housing (30) faces the second steam inlet section (41) of the low-pressure inner housing (40). The invention further relates to a method for operating a steam turbine (1a; 1b) according to the invention.

Description

description

Steam turbine and method of operating the same

The present invention relates to a steam turbine and a method for operating the steam turbine.

In steam power plants, steam is used to operate steam turbines as the working medium. The steam is heated in a steam boiler and flows as process steam via pipelines into the steam turbine. In the steam turbine is converted to the ^¬ before absorbed energy of the working medium in motion Sener ^¬ energy. By means of the kinetic energy of a gene is operated ^¬ rator which converts the mechanical power generated in electric power. Thereafter, the relaxed and cooled process steam flows into a condenser, where it is condensed by heat transfer in a heat exchanger and as liquid water again ^¬ leads to the boiler for heating ^¬ leads. Conventional steam turbines have at least one high-pressure part and at least one low-pressure part. At low pressure ^¬ part, the temperature of the process steam drops sharply, where ^¬ can come to it by partial condensation of the process steam. The low pressure part is very sensitive with regard to a moisture content of the process steam. Achieved the process steam in the low-pressure part of the steam turbine a wet ^¬ content of about 8 to 10 percent, measures should be taken to reduce the moisture content of the process steam before entering the low pressure part to an acceptable level.

In order to increase the efficiency of a steam power plant, the process steam is supplied for this purpose before entering the low-pressure part of a reheatening. During reheating, the process steam is heated so that the moisture content falls. In this intermediate superheating of the steam is complete mass flow to the high pressure part of the steam turbine ent ^¬ taken, the reheat supplied and approximately at raised the temperature of the live steam. Subsequently, the process steam is supplied to the low-pressure part. Without such reheat, the steam turbine would have to be stopped because condensed water droplets could impact the rotating turbine blades and thereby cause damage to the turbine.

In multi-stage steam turbines, such a reheating of the process steam is carried out between the individual turbine stages. This leads to a higher efficiency, since by means of the superheated steam more efficient mechanical energy can be generated in the turbine stages.

In the implementation of reheat systems in steam turbines, the material of the outer wall is highly stressed, in particular between the individual turbine stages. At the first turbine stage, the colder water vapor is removed, fed to the reheater and fed the heated process steam of the second turbine stage. Here tre ^¬ th in the outer wall in the transition between the first turbine stage and the second turbine stage high Temperaturdiffe ^¬ limit on. Since the end of the first turbine stage, from which the colder process steam is withdrawn, and the beginning of the second turbine stage, in which the hot process steam is supplied from the reheater, are close to each other, high thermal stresses occur in the outer wall. This can lead to leaks or cracks in the outer wall. Furthermore, there is the risk that when the cold process steam is removed from the first turbine stage, wet steam parameters prevail and, as a result, condensate is applied to the inner wall of the outer housing. The condensate cools the inner ^¬ side of the outer wall in addition. Thus, the thermal stress on the outer wall is increased. Thus, the superheated Pro ^¬ zessdampf may not cause harmful thermal stresses, the superheated process steam is cooled to reduce thermal stresses. This is usually done in upstream Einströmgehäusen. These additional However, inflow enclosures can lead to energy losses.

In a single-shell or single-stage steam turbine with reheat is overheated in two places

Process steam directed into the turbine. In this case, in particular the steam turbine outer casing is thermally heavily loaded by the occurring temperatures and pressures Tempe ^¬ . Steam turbines with reheat were previously either designed as a two-shell turbine housing or it was used lower steam parameters, so that a single-shell steam turbine outer casing was not overloaded. However, the required parameters that occur occur frequently above the possible parameters of single-shell turbine housings. European Patent EP 2 997 236 B1 discloses a steam turbine which at least partially takes account of the above problem.

The invention has for its object to provide a compact, si ^¬ chere and efficient steam turbine and a method for the corresponding operation of the steam turbine available.

The above object is solved by the claims. In particular, the above object is achieved by the steam turbine according to claim 1 and the method ge ^¬ claim 10. Further advantages of the invention will become apparent from the dependent claims, the description and the drawings. Here are features and details that are described in connection with the steam turbine

are, of course, also in connection with the method according to the invention and in each case vice versa, so that with respect to the disclosure of the individual aspects of the invention is always reciprocal reference or who ^¬ can. According to a first aspect of the invention, a steam turbine is provided. The steam turbine has a steam turbine outer casing. Furthermore, the steam turbine has a high-pressure inner housing with a first process steam inlet section and a first process ^¬ steam outlet section for conducting process steam through the high pressure inner housing from the first process steam inlet section to the first process steam outlet section in a first process steam expansion direction. Furthermore, the steam turbine, a low-pressure inner casing with a second Pro ^¬ zessdampf entry portion and a second process ^¬ steam outlet portion for conducting the process vapor through the low-pressure inner housing from the second process steam inlet portion to the second process steam exit portion in a second process steam Relaxation direction. In addition, the steam turbine has a reheater disposed downstream of the high pressure inner casing and upstream of the low pressure inner casing, with the high pressure inner casing and the low pressure inner casing disposed within the steam turbine outer casing. The high-pressure inner housing and the low-pressure inner housing are arranged such that the first steam inlet section of the high-pressure inner housing faces the second Dampfein ^¬ passage section of the low-pressure inner housing.

Is lower, that the first steam inlet portion of the high pressure inner casing section to the second Dampfeintrittsab ^¬ the low-pressure inner housing facing it can be understood that the first steam inlet portion of the high pressure inner casing tung in the opposite Rich ^¬ tung or substantially in the opposite RICH as the second steam inlet section of the low ^¬ pressure inner housing shows or is aligned. Entspre ^¬ accordingly extends the first process steam

Relaxation direction opposite or substantially opposite to the second process steam expansion direction.

That is, the high-pressure inner housing and the low-pressure inner housing are arranged such that a process ^¬ steam-flood direction by the high-pressure inner housing ent ^¬ opposite, in particular by 180 ° opposite, runs to a process steam flood direction through the low-pressure inner housing.

With the inventive arrangement of the high-pressure inner housing and the low-pressure inner housing is fundamentally averted from the conventional construction. In experiments that were carried out in the context of the present invention, it has been found that not only can be shortened by the inventive arrangement of the bearing distance, but also the steam turbine can be operated in a particularly secure manner. On ^¬ reason of the shortened bearing distance, the steam turbine can be built compact accordingly. This in turn results in a particularly favorable design with respect to the rotor dynamics of the steam turbine.

Using the present steam turbine, superheated process steam in the form of live steam can be fed into the high-pressure inner housing rotated counter to a steam direction and expanded to the pressure and temperature level of a so-called cold reheat. After the process steam has escaped from the high-pressure inner housing, the process steam can be led to the reheater. Reheater Process steam from the reheater can now be directed into the arranged in a main flow direction low-pressure inner housing and relax there to condensation in the steam turbine.

Under the low pressure inner housing is in this case a ^¬ In nengehäuse to understand in which at least on average, a lower pressure prevails or arises than in the high-pressure inner housing. That is, under the low-pressure inner housing can also be understood in particular a medium-pressure inner housing. In a preferred embodiment variant, a medium-pressure inner housing is therefore under the low-pressure inner housing to ver ^¬ stand.

The process steam is to be understood as steam, in particular water vapor, which flows through components of the steam turbine during operation of the steam turbine.

The inventive arrangement of the high pressure inner housing and the low pressure inner housing exciting forces in the low pressure inner housing can be minimized, since only the pressure difference from the intermediate superheating acts. Process steam can be routed directly into the next component, for example another low-pressure inner housing, for further relaxation and does not have to be redirected first. In the pre- ^¬ proposed arrangement also a sealing shell can be saved. Namely, at a second process steam discharge section, the process steam can be passed directly from the low-pressure inner housing or a medium-pressure inner housing into a low-pressure inner housing or a further low-pressure inner housing, since the process steam expansion direction of the low pressure. Medium pressure inner housing has the same direction as the process steam expansion direction of the further low-pressure inner housing.

In the present case, a direction of expansion means a direction in which the process steam is essentially moved or conducted. That is, if the process steam in a steam turbine section at ^¬ example spiral from left to right or

moved in a helical manner, a linear relaxation direction is to be understood as being simplified to the right. hen. Furthermore, in the present case, a pressure direction from a high-pressure region into a low-pressure region or into a pressure region at a lower pressure than in the high-pressure region is to be understood as an expansion direction. Accordingly, a portion is meant by an upstream steam turbine section, the entge ^¬ gene of the relaxation direction is arranged.

According to a development of the present invention, it is possible for a steam turbine downstream of the high-pressure inner housing to configure a process steam deflecting section for deflecting process steam from the first steam outlet section in a direction opposite to the first steam expansion direction into a cooling line of the steam turbine. wherein the cooling line is ausgestal ^¬ tet in a region adjacent to the high pressure inner housing. This allows cool process steam in a simple and space-saving way to cool the steam turbine outer casing and thus ver ^¬ spent for cooling the steam turbine. This in turn results in the fact that the steam turbine can be protected against overheating and thus operated very safe. For this purpose, the process steam can be deflected from the high-pressure inner housing in a main ^¬ flow direction and out to the outside of the high-pressure inner housing. For the desired Kühlef ^¬ fect the cooling pipe along an inner wall of the steam turbine outer casing and / or along an outer wall of the high-pressure ^¬ inner housing is arranged or designed from ^¬.

Further, it is possible that in a steam turbine according to the invention, the cooling line at least partially between, in particular directly between, an inner wall of the steam turbine outer casing and a ^{Außenwan ¬} tion of the high-pressure inner casing is arranged. That is to say, the process steam can be conducted at least in sections around the high-pressure inner housing or along the high-pressure inner housing and then directly or indirectly. be discharged directly through the steam turbine outer housing to the intermediate ^¬ superheater. As a result, an advantageous cooling effect for the steam turbine outer casing can be achieved.

Furthermore, it is possible that an inventive ^¬ SEN steam turbine, the cooling pipe is arranged additionally or alternatively at least partially between, in particular di rectly ^¬ between, an inner wall of the steam turbine outer housing and an outer wall of the low-pressure inner casing. That is to say, the process steam can also be conducted, at least in sections, around the low-pressure inner housing or along the low-pressure inner housing and subsequently be led away to the reheater by the outer turbine casing. As a result, the cooling effect for the steam turbine outer casing can be further enhanced. This will total betrach ^¬ tet a particularly space-saving, efficient and reliable functioning cooling system for the

Steam turbine created.

Moreover, in a steam turbine according to the present invention, it is possible that at an upstream end portion of the high-pressure inner casing on which the first process steam inlet portion is formed

A high-pressure sealing shell for sealing the upstream end portion of the high-pressure inner housing and at an upstream end portion of the low-pressure inner housing, on which the second process steam inlet portion is configured, a low-pressure sealing shell for sealing the upstream end portion of the low-pressure inner housing, wherein the High-pressure sealing shell and the low-pressure sealing shell are arranged adjacent to each other. In experiments that were carried out in the context of the present invention, it has been found that a steam turbine with the two sealing shells in this area easy to assemble, disassemble, maintain and to repair. Nevertheless, a relatively compact design can be achieved. In this case, an adjacent arrangement means an arrangement next to one another, ie, not necessarily directly next to one another. That is, between the sealing shells even more components can be arranged or the two sealing shells are preferably arranged at a small distance next to each other but not directly to each other.

Alternatively, it is possible that an inventive ^¬ SEN steam turbine at an upstream end portion of the high-pressure inner casing, is arranged on which the first Pro ^¬ zessdampf entry portion, and ei ^¬ nem upstream end portion of the low-pressure inner casing, to which the second process steam - Ingress section is configured, a common sealing shell for sealing the two end portions is arranged ^¬ . By this construction or measure, the steam turbine can be provided in a particularly compact. Since ^¬ over addition, the use of a further

Dichtschalte be waived. This results in a Ge ^¬ weight saving in the steam turbine and to a Redu ^¬ cation to the logistics involved in the production of the steam turbine.

In addition, in a steam turbine according to the invention at a downstream end portion of the low-pressure inner housing, a sealing web for sealing a Dampftur ^¬ binenbereichs between the downstream end portion of the low pressure inner housing and the steam turbine outer housing be configured. In the present steam turbine, the low-pressure inner housing flows around during operation with process steam, while the high-pressure inner housing is separated from the low pressure inner housing by the sealing web, which is preferably designed as inte ^¬ grated sealing web at the downstream end portion of the low-pressure inner housing. Under USAGE ^¬ extension of the sealing web may be on an inner sealing shell at downstream end portion of the low-pressure inner housing can be omitted. The sealing web has ei ^¬ nen significantly less complex structure as a sealing shell. At this point it should be mentioned that in the present case under a sealing shell a common in the prior art

Sealing cup is to be understood, which is therefore not described in detail here.

Another advantage may be when the Zwischenüber- is angeord ^¬ net superheater outside the steam turbine outer casing. This is especially with regard to the assembly, disassembly, maintenance and repair of the steam turbine of

Advantage. In a steam turbine according to the invention, it is also possible that the high-pressure inner housing and the low-pressure inner housing are provided as separate components. This has the advantage that the steam turbine can be constructed according to the modular principle ^¬ simple and inexpensive. The present invention preferably relates to the expansion of a process steam in a single steam turbine outer casing from a high pressure to a pressure below an intermediate superheat pressure. A low pressure relaxation can be done in a separate section of the same

Steam turbine or in a separate low-pressure steam turbine done.

In accordance with another aspect of the present invention, a method of operating a steam turbine as detailed above is provided. Thus, an inventive method brings the same benefits, as they have been described in detail with reference to the erfindungsge ^¬ Permitted steam turbine. The method comprises the following steps:

- Passing process steam from a process steam source

through the first process steam inlet section into the high-pressure inner housing, Passing the process steam from the first process steam inlet section to the first process steam exit section, and

Passing the process steam through the first process steam exit section from the high pressure inner housing via the process steam diverter section and the cooling line to the reheater.

By the method described above, the steam turbine can be cooled in a simple and compact manner. By a reliable cooling of the steam turbine this can also be operated in a secure manner. Thus, a method for reliably cooling a steam turbine is provided.

Further, the invention improving measures result

from the following description of various embodiments of the invention, which are shown schematically in the figures. All features and / or advantages resulting from the claims, the description or the drawing, including constructional details and spatial arrangements, can be essential to the invention, both individually and in the various combinations.

Each schematically shows: a block diagram for illustrating a steam turbine according to a first embodiment of the present invention, and

FIG. 2 is a block diagram showing a steam turbine according to a second embodiment of the present invention.

Elements with the same function and mode of operation are each provided with the same reference numerals in FIGS. 1 and 2. In Fig. 1, a steam turbine la according to a first Ausfüh ^¬ tion form is shown. The steam turbine has a steam la ^¬ turbine outer casing 20 in which a high pressure inner casing 30, a low-pressure inner casing 40 egg nes in the form of intermediate-pressure inner casing, and another low-pressure inner housing 90 are located. Upstream of the high-pressure inner housing 30, a live steam or process steam source 10 for supplying process steam to the high-pressure inner housing 30 is arranged. The high-pressure inner casing 30 includes a first process steam inlet portion 31 and a first Pro ^¬ zessdampf outlet section 32 for directing process steam through the high pressure inner casing 30 from the first process steam inlet section 31 for the first process steam outlet portion 32 in a first process steam Relaxation 33 on. The low-pressure inner casing 40 includes a second process steam inlet portion 41 and a second process vapor exit section 42 for conducting the process vapor through the low-pressure inner casing 40 from the second process steam inlet portion 41 to the second process steam outlet portion 42 in a second process ^¬ vaporous Relaxation direction 43 on. The steam turbine la further includes a reheater 50, which is disposed downstream of the high-pressure inner housing 30 and upstream of the low-pressure inner housing 40.

As shown in FIG. 1, the high pressure inner case 30 and the low pressure inner case 40 are arranged such that the first steam inlet portion 31 of the high pressure inner case 30 faces the second steam inlet portion 41 of the low pressure inner case 40.

Downstream of the high pressure inner housing 30, the steam ^¬ turbine la a process steam deflection section 60 for deflecting process steam from the first steam discharge section 32 in a direction opposite to the first steam expansion direction 33 in a cooling line 70 of the steam turbine la. The cooling line 70 is within the steam turbine ^¬ nen outer housing 20 in a region adjacent to the high pressure inner housing 30 configured. The cooling line 70 is also arranged in sections between an inner wall of the steam turbine outer housing 20 and an outer wall of the high-pressure inner housing 30. In addition, the cooling line 70 is arranged in sections between an inner wall of the steam turbine outer housing 20 and an outer wall of the low-pressure inner housing 40.

According to the first embodiment is on a

upstream end portion of the high-pressure inner housing 30, on which the first process steam inlet portion 31 is designed from ^¬ , arranged a high-pressure sealing shell 34 for at least partially sealing the upstream end portion of the high pressure inner housing 30. In addition, a low-pressure seal cup 44 is at an upstream end portion of the low pressure inner casing 40 is configured to which the second process steam inlet portion 41 arranged to at ^¬ least partial sealing of the upstream end portion of the low pressure inner casing 40th The high-pressure sealing shell 34 and the low-pressure sealing shell 44 are ^¬ arranged adjacent to each other. At a downstream end portion of the high-pressure inner housing 30, on which the ers ^¬ te process steam outlet portion 32 is configured, a further high-pressure sealing shell 35 for at least partially sealing the downstream end portion of the high-pressure inner housing 30 is arranged.

At a downstream end portion of the low pressure inner housing 40, a sealing land 80 for sealing a steam turbine area between the downstream Endab ^¬ section of the low pressure inner housing 40 and the Dampfturbi ^¬ nen outer housing 20 is configured. The reheater is disposed outside of the steam turbine outer casing 20. The high-pressure inner casing 30 and the low-pressure inner casing 40 are provided as separate components in a common steam turbines ^¬ NEN outer casing 20th With reference to FIG. 2, a steam turbine 1b according to a second embodiment will be described. The steam turbine 1b according to the second embodiment substantially corresponds to the steam turbine 1a according to the first embodiment. In place of the two separate sealing shells or the high-pressure sealing shell 34 and the low-pressure sealing shell 44 only ei ^¬ ne single sealing shell 100 between the high-pressure inner housing 30 and the low pressure inner housing 40 angeord ^¬ net.

With reference to FIG. 1, a method ge ^¬ Mäss an embodiment will be described subsequently yet. As part of the method, process steam is first conducted from the process steam source 10 through the first process steam inlet section 31 into the high-pressure inner housing 30. Subsequently, the

Process steam fed from the first process steam inlet portion 31 to the first process steam outlet portion 32 and then through the first process steam exit portion 32 from the high pressure inner casing 30 through the process steam deflecting section 60 and the cooling conduit 70 to the intermediate ^¬ superheater 50. Here, the process steam is the cooling line 70 for cooling the steam turbine outer housing 20 and the steam turbine la along the high-pressure inner housing 30 and along the low-pressure inner housing 40 passed.

After the process steam in the reheater 50 has been heated at the same pressure to a predefined temperature, the heated or superheated process steam from the reheater 50 is passed through the second process steam inlet section 41 into the low-pressure or medium-pressure inner housing. From there, the process steam is passed into the further low-pressure inner housing with the same direction of expansion. There, the process steam can relax wei ^¬ ter and condense. Reference sign list

1 steam turbine

10 process steam source

20 turbine outer casing

30 high-pressure inner housing

31 first process steam inlet section

32 first process steam outlet section

33 first process steam expansion direction

34 high-pressure sealing shell

35 high-pressure sealing shell

40 low-pressure inner housing

41 second process steam inlet section

42 second process steam outlet section

43 second process steam expansion direction

44 low-pressure sealing shell

50 reheaters

60 process steam deflection section

70 cooling line

80 sealing bar

90 low-pressure inner housing

100 sealing cup

Claims

claims

1. Steam turbine (la; lb) comprising a steam turbine outer housing (20), a high pressure inner casing (30) having a first process steam entry portion (31) and a first process steam outlet portion (32) for directing process ^¬ vapor- the high-pressure inner casing (30) from the first Pro ^¬ zessdampf entry portion (31) for the first process steam outlet portion (32) in a first process steam relaxation direction (33), a low-pressure inner housing (40) with a second process steam entry portion (41 ) and a second process steam outlet portion (42) for passing process vapor through the low-pressure inner casing (40) from the second process steam entry portion (41) to the second Pro ^¬ zessdampf outlet portion (42) (in a second process ^¬ steam-relaxation device 43 ), and a reheater (50) disposed downstream of the high-pressure inner housing (30) and upstream of the low-pressure inner housing (40), the Hochd jerk inner housing (30) and the low ^¬ pressure inner housing (40) within the steam turbine outer housing (20) are arranged,

characterized in that

the high-pressure inner housing (30) and the low-pressure inner housing (40) are arranged such that the first steam inlet section (31) of the high-pressure inner housing (30) faces the second steam inlet section (41) of the low-pressure inner housing (40).

2. Steam turbine (la; lb) according to claim 1,

characterized in that

downstream of the high-pressure inner housing (30), a process ^¬ steam deflection section (60) for deflecting process steam from the first steam discharge section (32) in a direction opposite to the first steam expansion direction (33) in a cooling line (70) of the steam turbine (la; lb) is configured, wherein the cooling line (70) in a region adjacent to the high-pressure inner housing (30) is configured.

3. Steam turbine (la; lb) according to claim 2,

characterized in that

the cooling line (70) at least in sections between, is arranged in the special ^¬ directly between, an inner wall of the steam turbines ^¬ NEN outer housing (20) and an outer wall of the high-pressure inner casing (30).

4. steam turbine (la; lb) according to one of claims 2 to 3, characterized in that

the cooling line (70) at least in sections between, is arranged in the special ^¬ directly between, an inner wall of the steam turbines ^¬ NEN outer housing (20) and an outer wall of the low-pressure ^¬ inner housing (40).

5. Steam turbine (la) according to one of the preceding claims, characterized in that

at an upstream end portion of the high pressure inner case (30) on which the first process steam entrance portion (31) is configured, a high pressure seal cup (34) for at least partially sealing the upstream end portion of the high pressure inner case

(30) and at an upstream end portion of the low pressure inner case (40) on which the second process vapor inlet portion (41) is configured, a low pressure sealing cup (44) for at least partially sealing the upstream end portion of the low pressure inner case

(40) are arranged, wherein the high-pressure sealing shell (34) and the low-pressure sealing shell (44) are arranged adjacent to each other.

6. steam turbine (lb) according to one of claims 1 to 4, characterized in that

at an upstream end portion of the high pressure inner case (30) on which the first process steam entrance portion (31) is formed, and at an upstream end portion of the low pressure inner case

(40) at which the second process steam inlet section

(41) is designed, a common sealing shell (100) for at least partially sealing the two end portions is arranged.

7. steam turbine (la; lb) according to one of the preceding claims,

characterized in that

at a downstream end portion of the low pressure inner housing (40) a sealing web (80) for sealing a steam turbine between the downstream Endab ^¬ section of the low pressure inner housing (40) and the Dampftur ^¬ binen outer housing (20) is configured.

8. steam turbine (la; lb) according to one of the preceding claims,

characterized in that

the reheater is located outside of the steam turbine outer casing (20).

9. steam turbine (la; lb) according to any one of the preceding claims,

characterized in that

the high pressure inner housing (30) and the low pressure inner housing (40) are provided as separate components in a single outer turbine shell (20).

10. A method of operating a steam turbine (1a, 1b) according to any one of the preceding claims, comprising the steps of:

Passing process steam from a process steam source (10) through the first process steam inlet section (31) into the high pressure inner housing (30),

Directing the process steam from the first process steam

Inlet section (31) to the first process steam

Exit section (32), and

Passing the process steam through the first process steam outlet section (32) from the high-pressure inner housing (30) via the process steam deflection section and the cooling ^¬ line (70) to the reheater (50).