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Independent of the grammatical term usage, individuals with male, female or other gender identities are included within the term.
FIELD OF THE INVENTION
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The present invention relates to a steam turbine, in particular of a reaction type. Furthermore, the present invention relates to an electric generation system including the steam turbine. Still further, the present invention relates to a method of operating a steam turbine as well as to a method of manufacturing a steam turbine.
PRIOR ART
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EP 3 409 895 A1 discloses a nozzle casing component for a steam turbine comprising a first section extending along a circumferential direction of the steam turbine and a second section extending along the circumferential direction of the steam turbine. The first section comprises a flow channel and an outlet configured such that a first inlet steam flow flowing through the flow channel is injectable through the outlet into a flow path of the steam turbine upstream of a control wheel.
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WO 2018/001651 A1 discloses a turbine comprising an outer casing, a plurality of nozzle blades, a plurality of stator blades, a nozzle valve casing supporting the plurality of nozzle blades, the nozzle valve casing being fixed to the casing, a stator blade carrier supporting the plurality of stator blades, the stator blade carrier being supported by the nozzle valve casing.
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DE 102015212933 A1 discloses a guide device for a turbine stage of a turbine, the guide device comprising an inner guide vane ring and an outer guide vane ring and a plurality of guide vanes fastened between the inner guide vane ring and the outer guide vane ring.
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It has been observed that conventionally, a steam turbine is restricted regarding different operation parameters of entry steam entering the steam turbine.
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Thus, there may be a need for a steam turbine, a method of manufacturing a steam turbine, a method of operating a steam turbine as well as a need for an electric energy generation system, wherein flexibility and versatility is provided regarding the characteristics of an entry steam which is supplied to the steam turbine to cause rotation of a rotor.
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This need may be satisfied by the subject-matter of the independent claims. The dependent claims specify particular embodiments of the present invention.
SUMMARY OF THE INVENTION
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According to an embodiment of the present invention it is provided a steam turbine, in particular of a reaction type, comprising: a stator having a first stator portion providing a first steam operation space and having a second stator portion providing a second steam operation space, a rotor having a first rotor portion and a second rotor portion, the rotor being supported to be rotatable within the stator; first movable nozzles mounted at the first rotor portion and arranged within the first steam operation space; second movable nozzles mounted at the second rotor portion and arranged within the second steam operation space; first stator nozzles mounted at the first stator portion to be within the first steam operation space; second stator nozzles mounted at the second stator portion to be within the second steam operation space; a first steam inlet provided at the first stator portion and arranged to guide a first entry steam to the first steam operation space; a second steam inlet provided at the second stator portion and arranged to guide a second entry steam to the second steam operation space; and a partition wall mounted at the stator to be arranged between the first stator portion and the second stator portion, thereby separating the first steam operation space from the second steam operation space.
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The steam turbine may in particular be of a reaction type. The reaction type steam turbine may develop torque by reacting to the gas (e.g. steam) or fluid's pressure or mass. Thereby, the pressure of the gas or fluid (also referred to as steam in the following) changes as it passes through the turbine rotor blades. A pressure casement (e.g. out-er/inner casing, see below) may be required to contain the working fluid as it acts on the turbine stage(s) or the turbine may be fully immersed in the fluid flow. The casing may contain and direct the working fluid and for water turbines, may maintain the suction imparted by the draft tube.
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The working fluid for operating the steam turbine may be steam, in particular water steam. The first stator portion may cover a first axial region of the stator and the second stator portion may cover a second axial region of the stator. Thereby, the axial direction corresponds to the rotation axis of the rotor. Similarly, the first rotor portion may be arranged in the first axial region and the second rotor portion may be arranged in the second axial region. The rotor may be integrally formed covering the first rotor portion and the second rotor portion.
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During operation, the rotor, and particularly the single rotor, is driven by the interaction of the first entry steam within the first steam operation space and the interaction of the second entry steam within the second steam operation space thereby respectively impacting on the first movable nozzles, the first stator nozzles and the second movable nozzles and the second stator nozzles. The first/second movable/stator nozzles may be configured as blades having an airfoil profile. The movable nozzles rotate with the rotor while the stator nozzles are fixed relative to the stator during operation.
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The movable/stator nozzles may be mounted across an entire circumference. Such circumferentially surrounding nozzles may be present at plural axial positions in the first steam operation space as well as the second steam operation space. The first movable/stator nozzles may be configured and arranged substantially mirror-symmetrically to the second movable/stator nozzles, wherein a mirror plane may be located at an axial center of the partition wall. According to other embodiments of the present invention, a mirror symmetry with respect to an axial center of the plane arranged in the axial center of the partition wall may not be present or is not necessarily be present. For example, first movable/stator nozzles may have a number or a number of stages which is same or different from the number or number of stages of the second movable/stator nozzles. The configuration and number and/or number of stages of the first movable/stator nozzles and the second movable/stator nozzles may be adapted depending on for example a steam characteristics of the first entry steam and/or second entry steam.
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The steam turbine may allow to be (concurrently) operated with a first entry steam and a second entry steam which have different steam characteristics or steam parameters. Thereby, high flexibility is provided. For example, not two individual steam turbines are required to utilize the first entry steam and the second entry steam for driving the rotor and thus generating electric energy when the turbine is connected to an electric generator.
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The first movable/stator nozzles and the second movable/stator nozzles may be arranged and configured regarding their respective geometry such that the rotor rotates in the same rotation direction when (only) the first entry steam is supplied to the turbine via the first steam inlet or when (only) the second entry steam is provided to the turbine via the second steam inlet. Thereby, the geometry and/or structure of the first movable/stator nozzles may substantially be mirror-symmetrical with respect to the second movable/stator nozzles wherein a mirror plane is located in an axially centered plane of the partition wall.
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The steam turbine may, for enclosing the first steam operation space, include a first inner casing and/or may contain for enclosing or delimiting the second steam operation space comprise a second inner casing. The steam turbine may thus comprise a double inner casing without a control wheel for high inlet steam parameters with two different steam parameters. Conventionally, two separate steam turbines may have been employed in order to operate the turbines with steam having two different steam parameters. The steam turbine may be operated with the first and second entry steam having two different steam parameters, for example different temperature and/or different pressure.
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According to an embodiment of the present invention, the partition wall is formed as a ring, in particular composed of at least two connected ring portions, radially extending between an outer casing of the stator and the rotor.
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The partition wall may substantially be formed from or comprising metal and may for example be composed of two connected half ring portions. The partition wall may substantially comprise a flat plate, wherein surfaces of the plate may be oriented perpendicular to the axial direction. The partition wall may substantially be arranged or located at an axial center of the steam turbine. In other embodiments, the partition wall may not be located at an axial center of the steam turbine, for example in the case that the first movable/stator nozzles have a different number of stages of or different number than the second movable/stator nozzles such that also potentially the first steam operation space is of a different dimension than the second steam operation space. Thereby, flexibility for the design is provided.
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According to an embodiment of the present invention, the steam turbine further comprises at least one sealing member adapted to provide sealing between the partition wall and the rotor.
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The sealing member may circumferentially extend in a gap between the rotor and the partition wall. The sealing member may comprise conventionally available sealing components. The sealing member may provide the sealing between the partition wall and the rotor such that the first steam operation space is substantially separated and gasketed from the second steam operation space such that the first entry steam is not mixed with the second entry steam, but both entry steams may act independently from each other substantially without interfering with each other. However, partial leakage from one side of the partition wall to the other side may not completely be avoidable.
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According to an embodiment of the present invention, the first stator portion comprises a first outer casing and/or a first inner casing enclosing the first steam operation space, wherein the second stator portion comprises a second outer casing and/or a second inner casing enclosing the second steam operation space.
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The first/second outer casing may be arranged radially outwards from the first/second inner casing, respectively. The first/second inner casing may substantially define the geometry or shape of the first/second steam operation space by for example delimiting and/or restricting the respective steam operation space. The first/second inner casing may substantially be supported or mounted at the stator. Thereby, the first/second steam operation space may be shaped and delimited as required.
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According to an embodiment of the present invention, within the first steam operation space the first entry steam impacts onto the first movable nozzles and the first stator nozzles causing rotation of the rotor in a first rotation direction, wherein within the second steam operation space the second entry steam impacts onto the second movable nozzles and the second stator nozzles causing rotation of the rotor in the first rotation direction.
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It is noted that impact of the first entry steam onto the first movable nozzles and the first stator nozzles causes rotation of the rotor in the same rotation direction as the impact of the second entry steam onto the second movable nozzles and the second stator nozzles. Thus, both, the first entry steam as well as the second entry steam drive rotation of the rotor in the same direction thereby improving and enhancing energy output for example of an energy generation system employing the steam turbine.
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According to an embodiment of the present invention, the first movable nozzles and the first stator nozzles and/or the second movable nozzles and the second stator nozzles are arranged in one or more stages or sets (e.g. 2 stages, 3 stages, 4 stages or a higher number of stages); and/or wherein the first movable nozzles alternate (along the axial direction) with the first stator nozzles and/or the second movable nozzles alternate with the second stator nozzles.
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Thereby, conventional nozzle designs are supported which are for example employed for providing a reaction turbine.
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According to an embodiment of the present invention, the steam turbine further comprises a first exhaust outlet in communication with a downstream portion of the first steam operation space; a second exhaust outlet in communication with a downstream portion of the second steam operation space; in particular at least one pipe configured to selectively connect the first steam inlet with the second exhaust outlet and/or configured to selectively connect the second steam inlet with the first exhaust outlet.
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The first exhaust outlet may be arranged in a flow direction of the first entry steam downstream the first steam inlet. The second exhaust outlet may be arranged, with respect to a flow direction of the second entry steam (substantially opposite to the flow direction of the first entry steam) downstream the second steam inlet. Advantageously, at least one pipe may also be provided which may allow to establish a steam communication between the first steam inlet and the second exhaust outlet and/or to the second steam inlet and the first exhaust outlet. For example, the first exhaust steam expelled at the first exhaust outlet may have a steam parameter which is suitable as second entry stream, for example similar to the steam characteristics of the second entry steam. Thus, the second entry steam may in particular be composed of portions of first entry steam at the first exhaust outlet and in particular additional second entry steam portion which are then mixed to enter for example the second steam inlet, wherein the mixed steam may have a required steam characteristics, in particular first or second steam parameters. Thereby, flexibility and efficiency of the steam turbine may be improved. The at least one pipe may for example comprise one or more of valves which may be controlled to provide the selective connection.
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According to an embodiment of the present invention, the steam turbine further comprises a first bleed outlet in communication with a portion of the first steam operation space; and/or a second bleed outlet in communication with a portion of the second steam operation space.
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The respective first/second bleed outlets may allow flexible operation of the steam turbine and/or control of the steam turbine, as is also conventionally applied to a reaction type turbine.
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According to an embodiment of the present invention, the steam turbine further comprises a first rotor bearing connected to the first stator portion for supporting rotor at a first side; a second rotor bearing connected to the second stator portion for supporting rotor at a second side.
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The respective first/second rotor bearings may be configured as conventionally known. Thereby, rotatable support of the rotor is enabled.
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According to an embodiment of the present invention it is provided an electric energy generation system, including: a steam turbine according to any one of the preceding embodiments; an electric generator having a generator rotor, wherein the steam turbine rotor and the generator rotor are coupled, in particular via a gear box.
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The electric generator may comprise a stator having plural stator windings. The generator rotor may comprise one or more electromagnets and/or one or more permanent magnets. Rotation of the generator rotor with respect to the generator stator may induce or generate an electric power stream at the stator windings. The gearbox may allow transformation of a rotational speed between the generator rotor and the steam turbine rotor as required. The electric energy generation system may comprise only a single electric generator and/or a single gearbox. This solution may be advantageous with respect to a system comprising two completely separate turbines being connected to two electric generators, for example, also requiring two gearboxes.
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It should be understood, that features, individually or in any combination, disclosed, described, explained or provided for a steam turbine may also, individually or in any combination, be applied or be provided to a method of operating a steam turbine and/or to a method of manufacturing a steam turbine according to embodiments of the present invention and vice versa.
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According to an embodiment of the present invention it is provided a method of operating a steam turbine, in particular of a reaction type, in particular according to any one of the preceding embodiments, the method comprising: guiding a first entry steam into a first steam operation space within which the first entry steam impacts onto first movable nozzles mounted at a rotor and first stator nozzles mounted at a stator causing rotation of the rotor in a first rotation direction, guiding a second entry steam into a second steam operation space within which the second entry steam impacts onto second movable nozzles mounted at the rotor and second stator nozzles mounted at the stator causing rotation of the rotor in the first rotation direction, wherein the first steam operation space is separated from the second steam operation space.
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The method may utilize a steam turbine according to one of the above-described embodiments. Thereby, flexibility of operating the steam turbine may be provided.
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According to an embodiment of the present invention, the first entry steam is characterized by first steam parameters, in particular including temperature and/or pressure, and the second entry steam is characterized by second steam parameters being different from first steam parameters.
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For example, the first steam parameters may have the same or a different temperature than the second steam parameters and/or the first steam parameters may define a same or a different pressure than the second steam parameters.
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According to an embodiment of the present invention, the method further comprises driving a single generator by rotating the steam turbine rotor.
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According to an embodiment of the present invention it is provided a method of manufacturing a steam turbine, in particular of a reaction type, in particular according to any one of the preceding embodiments, the method comprising: providing a stator with a first stator portion providing a first steam operation space and with a second stator portion providing a second steam operation space, providing a rotor having a first rotor portion and a second rotor portion; supporting the rotor to be rotatable within the stator; mounting first movable nozzles at the first rotor portion and arranging them within the first steam operation space; mounting second movable nozzles at the second rotor portion and arranging them within the second steam operation space; mounting first stator nozzles at the first stator portion to be within the first steam operation space; mounting second stator nozzles at the second stator portion to be within the second steam operation space; providing a first steam inlet at the first stator portion arranged to guide a first entry steam to the first steam operation space; providing a second steam inlet provided at the second stator portion arranged to guide a second entry steam to the second steam operation space; and mounting a partition wall at the stator to be arranged between the first stator portion and the second stator portion, thereby separating the first steam operation space from the second steam operation space.
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The invention is not restricted to the embodiments described or illustrated below.
BRIEF DESCRIPTION OF THE DRAWINGS
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The figure schematically illustrates in a cross-sectional view an electric energy generation system according to an embodiment of the present invention including a steam turbine according to an embodiment of the present invention.
DETAILED DESCRIPTION OF EMBODIMENTS
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The electric energy generation system 1 schematically illustrated in the figure in a cross-sectional view includes a steam turbine 2 according to an embodiment of the present invention which is of a reaction type. Furthermore, the energy generation system 1 comprises an electric generator 3 having a generator rotor 4, as well as a generator stator 5. Optionally, the electric generator 3 includes a not illustrated gearbox. A steam turbine rotor 6 is thereby coupled to the generator rotor 4.
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The steam turbine 2 comprises a stator, in particular steam turbine stator 7, having a first stator portion 7a and a second stator portion 7b. The first stator portion 7a provides a first steam operation space 8a and the second stator portion 7b provides a second steam operation space 8b. The respective steam operation spaces 8a, 8b are respectively enclosed by below described casings. The steam turbine 2 further comprises a rotor 6 which has a first rotor portion 6a and a second rotor portion 6b, wherein the rotor 6 is supported to be rotatable within the stator 7.
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The steam turbine 2 further comprises first movable nozzles 9a which are mounted at the first rotor portion 6a and which are arranged within the first steam operation space 8a. The steam turbine further comprises second movable nozzles 9b which are mounted at the second rotor portion 6b and are arranged within the second steam operation space 8b. The steam turbine 2 further comprises first stator nozzles 10a mounted at the first stator portion 7a to be within the first steam operation space 8a. The turbine 2 further comprises second stator nozzles 10b which are mounted at the second stator portion 7b to be within the second steam operation space 8b.
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The turbine 2 further includes a first steam inlet 11a provided at the first stator portion 7a and arranged to guide a first entry steam 12a to the first steam operation space 8a. The turbine 2 further includes a second steam inlet 11b provided at the second stator portion 7b and arranged to guide a second entry steam 12b to the second steam operation space 8b.
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Furthermore, the turbine includes a partition wall 13 mounted at the stator 7 to be arranged between the first stator portion 7a and the second stator portion 7b, thereby separating the first steam operation space 8a from the second steam operation space 8b. The figure provides a cross-sectional view, the partition wall is, however, formed as a ring across an entire circumference around the rotor 6 the ring having a rotational symmetry with respect to the rotation axis 14 of the rotor 6. The partition wall 13 may for example be composed of two half ring portions which may be bolted together using bolts and/or threaded holes 15 as illustrated in the figure.
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The steam turbine further comprises at least one sealing member 16 adapted to provide sealing between the partition wall 13 and the rotor 6.
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The first stator portion 7a comprises a first outer casing 17a and a first inner casing 18a enclosing the first steam operation space 8a. The second stator portion 7b comprises a second outer casing 17b and a second inner casing 18b enclosing the second steam operation space 8b.
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Within the first steam operation space 8a, the first entry steam 12a impacts onto the first movable nozzles 9a and the first stator nozzles 10a causing rotation of the rotor 6 in a first rotation direction 19. Within the second steam operation space 8b, the second entry steam 12b impacts onto the second movable nozzles 9b and the second stator nozzles 10b causing rotation of the rotor 6 in the first rotation direction 19.
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As can be seen in the figure, the first movable nozzles and the first stator nozzles are arranged in two stages, a first stage 20a and a second stage 21a. Similarly, the second movable nozzles and the second stator nozzles are arranged in a first stage 20b and a second stage 21b. In the illustrated embodiment, the steam turbine 2 is substantially mirror-symmetrically configured, wherein the mirror plane 22 is present at an axial center of the partition wall 13. The symmetry plane 22 is oriented to be perpendicular to the rotation axis 14 of the rotor 6.
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As can be seen in the figure, the respective movable and stator nozzles alternate with each other in the axial direction being parallel to the rotation axis 14. The steam turbine further comprises a first exhaust outlet 23a in communication with a downstream portion of the first steam operation space 8a and further comprises a second exhaust outlet 23b in communication with a downstream portion of the second steam operation space 8b. Thereby, downstream/upstream is defined with respect to the respective flow direction of the considered steam. In particular, the first entry steam 12a streams in the streaming direction 24a which is opposite to the streaming direction 24b according to which the second entry steam 12b streams through the second steam operation space 8b.
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According to an embodiment of the present invention, at least one pipe or pipe system 25a may be provided to for example connect the first steam inlet 11a to the second exhaust outlet 23b. Additionally or alternatively, a pipe 25b may be provided which may selectively connect the second steam inlet 11b with the first exhaust outlet 23a.
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The steam turbine further comprises a first bleed outlet 26a in communication with a portion of the first steam operation space 8a and further may comprise a second bleed outlet 26b (not illustrated in the figure in detail) in communication with a portion of the second steam operation space 8ab. The respective bleed outlets 26a,b are optional features.
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The steam turbine 2 further comprises a first rotor bearing 27a connected to the first stator portion 7a for supporting the rotor 6 at a first side and further comprises a second rotor bearing 27b connected to the second stator portion 7b for supporting the rotor 6 at the second side.
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At axial ends the turbine comprises a front inner steam gland 28a, a front outer steam gland 29a and a rear inner steam gland 28b and rear outer steam gland 29b.
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A method of operating the steam turbine 2 includes according to an embodiment of the present invention to guide the first entry steam 12a into the first steam operation space 8a within which the first entry steam 12a impacts onto first movable nozzles 9a mounted at the rotor 6 and first stator nozzles 10a mounted at the stator 7 causing rotation of the rotor 6 in the first rotation direction 19. Further, a second entry steam 12b is guided into a second steam operation space 8b within which the second entry steam 12b impacts onto second movable nozzles 9b and second stator nozzles 10b mounted at the stator 7 causing rotation of the rotor 6 in the first rotation direction 19. Thereby, the first steam operation space 8a is separated from the second steam operation space 8b.
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The first entry steam may have first steam parameters and the second entry steam may have second steam parameters which may be different from the first steam parameters. The method may further comprise to drive a single generator 3 by rotating the steam turbine rotor 6. Embodiments of the present invention further comprise or provide a method of manufacturing the steam turbine 2 as has been described above.
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Embodiments of the present invention may provide at least one or some of the advantages listed below:
- Only one turbine instead of two turbines is needed for operating the energy generation system.
- One turbine with a short bearing span may be utilized.
- It is possible to use high steam parameters.
- The temperature of the first or second steam may for example be between 500°C and 600°C and/or the pressure may for example be between 900 bar and 1100 bar, for example. It is possible to use this embodiment with two different steam parameters.
- Eight inlet steam connections may be provided for the turbine casing.
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Embodiments may provide a double casing turbine without a control wheel. The technical solution may be possible for use for high steam parameters on the inlet steam. Thereby, embodiments may provide two inner casings. The first turbine portion may be placed on the left-hand side in the figure and the second turbine portion may be arranged at the right-hand side in the figure. Each turbine portion may comprise an inner casing and also an outer casing, wherein the inner casing is placed into the outer casing. In the middle between the turbine portions, where is placed the partial wall (for example wall 13) which may split one body of the turbine into two separate portions of the turbine 2. The first turbine portion on the left side and also the second turbine portion on the right side are thereby provided. Both inner casings may enable to use a bleed within two drums. Steam from the steam exhaust 1 may be used for the steam inlet 2 by crossover piping. Conventional components may be utilized such as a front and a rear bearing system consisting of front and rear bearing (radial +axial-front part and radial-rear part), rotor flange, front and rear bearing pedestals, etc.