Power generation turbine using coolant extracted from rotor cavity

Abstract

The turbine comprises a housing (51) and a rotor (43) housed in the housing for rotation. The high-pressure region (71) and the low-pressure region (73) are disposed adjacent to the rotor shaft and separated by a high-pressure encapsulation seal (75) surrounding the rotor shaft. The high-pressure encapsulation seal separates the high-pressure region and the low-pressure region from each other; and the high pressure region is positioned at a forward side of the high pressure package seal and the low pressure region is positioned at a rearward side of the high pressure package seal. A first rotor cavity (77) is fluidly coupled with the high pressure region and is adapted to provide a flow of coolant to an upstream section of the rotor. A second rotor cavity (83) is fluidly coupled with the low pressure region and adapted to provide a flow of coolant to a downstream section of the rotor. A sealing member (85) separates the first rotor cavity and the second rotor cavity from each other.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to power generating turbomachines, such as expanders and gas turbines. BACKGROUND

[0002] Turbomachines are commonly used to generate mechanical power by expansion of high pressure and high temperature process fluid. The process fluid flows through a flow path extending through a plurality of turbomachine stages. Each stage comprises an annular row of stationary vanes, also referred to as stator vanes, and an annular row of rotor vanes arranged downstream of the annular row of stationary vanes with respect to the flow direction of the expanding process fluid. The rotor vanes are mounted around a respective rotor disc and form, together with the rotor disc, a rotor wheel of the rotor. The rotor is accommodated in a casing and is adapted to rotate around a rotor axis under the action of the thrust of the expanding gas flowing along the flow path. A wheel space is formed between radially inwardly directed end portions of the stationary vanes in each annular row of stationary vanes and the rotor wheel.

[0003] In order to prevent thermal damage to the rotor wheel and to prolong its service life, it is common practice to purge the wheel space with a flow of cooling process fluid at a suitable pressure. The cooling process fluid prevents hot process fluid from escaping into the wheel space from the flow path. Additionally or alternatively, the cooling and pressurized process fluid is used to cool the rotor vanes. Cooling fluid cavities or conduits are arranged in the rotor through which the cooling process fluid is delivered to the wheel space and / or the vane cooling conduits through suitable holes, slots and calibrated passages.

[0004] The cooling process fluid has to be at an appropriate pressure to reach the wheel space and / or the vanes in several locations along the turbomachine flow path to overcome the pressure head losses through the conduits and the pressure of the process fluid in the flow path. The pressure of the process fluid along the flow path decreases in an upstream to downstream direction, i.e. in a front to back direction, after expansion in the sequentially arranged stages of the turbomachine.

[0005] It becomes challenging to provide a cooling fluid at a suitable pressure level, especially in the most upstream stages of the flow path, in particular in turbomachines working at high pressure levels, such as supercritical expanders commonly used in Allam cycles and similar thermodynamic cycles.

[0006] It is important for improving the overall efficiency of the turbomachine and preventing thermal damage to the rotor components to provide appropriate cooling and / or purging and at the same time to reduce the amount of cooling fluid, in particular when the turbomachine is working at high temperature and high pressure conditions.

[0007] In some known turbomachines, such as gas turbine engines, process fluids at different pressure levels are extracted from different stages of the air compressor of the gas turbine engine and delivered to different portions of the turbine rotor. This arrangement cannot be implemented in turbomachines that do not include an in-line compressor, such as expanders of the oxy-fuel combustion cycle, and in turbomachines with a central tie rod.

[0008] Therefore, a more efficient arrangement for supplying cooling process gas to the wheel space of a power generation turbomachine would be welcome in the art. SUMMARY

[0009] According to one aspect, a power generation turbomachine, such as an expander, is disclosed herein and includes a housing and a plurality of stages. Each stage includes an annular row of stationary vanes fixedly arranged in the housing and an annular row of rotor vanes forming part of a rotor. Each annular row of rotor vanes is either mountable on a respective rotor wheel or integral with a portion of a rotor shaft. The rotor shaft includes a forward shaft portion and an aft shaft portion. The annular rows of rotor vanes are arranged between the forward shaft portion and the aft shaft portion and are either directly mounted on these portions and / or mounted on disks stacked on each other between the forward shaft portion and the aft shaft portion. The turbomachine stages are arranged in succession in a forward-aft direction from an uppermost upstream stage to a lowermost downstream stage and define an expansion flow path extending from an intake side to a discharge side of the turbomachine.

[0010] As used herein, "upstream" and "downstream" are terms indicating the direction of flow of process fluid through the expansion flow path of the turbomachine or of coolant through one of the turbomachine components.

[0011] As used herein, "forward" and "aft" refer to the direction of flow of process gas through the expander 3. In particular, "forward" indicates a position on the intake side of the turbomachine and "aft" indicates a position on the discharge side of the turbomachine. Thus, as used herein, the "forward-aft" direction is the direction from the intake end of the turbomachine towards the discharge end, i.e. the direction of flow of process gas through the turbomachine for expansion.

[0012] The turbomachine further includes a high pressure region adjacent to the rotor shaft and more particularly to the forward shaft portion thereof or surrounding the forward shaft portion thereof. The turbomachine further includes a low pressure region adjacent to the rotor shaft and more particularly to the forward shaft portion or surrounding the forward shaft portion. The low pressure region is arranged downstream of the high pressure region in the forward-aft direction, i.e. in the direction of flow of process fluid across the turbomachine. The high pressure region and the low pressure region are positioned upstream relative to the direction of flow of process fluid being expanded in the turbomachine of the stationary vanes and rotor vanes forming an expansion stage of the turbomachine.

[0013] In some embodiments, the high pressure region and the low pressure region can extend around the rotor shaft, for example in the form of respective annular plenums.

[0014] The high pressure region and the low pressure region are separated from each other by a high pressure containment seal around the rotor shaft. The high pressure region is arranged upstream of the high pressure containment seal with respect to the fore-aft direction, i.e. on the forward side of the high pressure containment seal. The low pressure region is arranged downstream of the high pressure containment seal with respect to the fore-aft direction, i.e. on the aft side of the high pressure containment seal.

[0015] The first rotor cavity is fluidly coupled with the high pressure region and is adapted to provide a coolant flow, i.e. a cooling fluid flow, to the upstream section of the rotor.

[0016] The second rotor cavity is fluidly coupled with the low pressure region and is adapted to provide a coolant flow, i.e. a cooling fluid flow, to the downstream section of the rotor. The coolant can be a side flow of the same process fluid which is expanded through the expansion flow path. The process fluid used as coolant flows from the high pressure region to the first rotor cavity. Process fluid leaking through the high pressure containment seal enters the low pressure region and is conveyed from this low pressure region to the second rotor cavity at a lower pressure than the process fluid in the first rotor cavity. The sealing member separates the first rotor cavity and the second rotor cavity from each other.

[0017] The low pressure region adjacent to or around the rotor shaft can be fluidly coupled with a first wheel space arranged between the stationary vanes of the first annular row and the rotor vanes of the first annular row, i.e. between the rotor vanes of the first expansion stage seen in the fore-aft direction along the expansion flow path. In some embodiments, the low pressure region and the first wheel space are at substantially the same pressure. As understood herein, “at substantially the same pressure” means that no isolating seal is provided between the low pressure region and the first wheel space, such that the first wheel space forms part of the low pressure region. The first wheel space receives a coolant flow from the low pressure region adjacent to or around the rotor shaft.

[0018] Thus, the coolant leaking through the high pressure containment seal is divided into a first flow which is directed to the first wheel space and used to purge the first wheel space between the stationary vanes and the rotor vanes of the first, i.e. most upstream, stage of the turbine, and a second flow which is directed towards the second rotor cavity and used to cool and / or purge the downstream section of the rotor. The coolant at a higher pressure from the high pressure region adjacent to or around the rotor shaft is fed into the first rotor cavity and used to cool or purge the upstream section of the rotor which requires a higher pressure coolant. The upstream section of the rotor includes rotor members such as rotor vanes and wheel spaces between the first annular row of rotor vanes and the downstream rotor section.

[0019] Thus, the flow rate of coolant leaking through the high pressure containment seal can be higher than the flow rate required for purging or cooling the first wheel space, since part of the coolant leaking through the high pressure containment seal is used for purging the downstream section of the rotor, where a lower pressure of the coolant is sufficient.

[0020] Thus, it is achieved that the turbomachine is particularly efficient, since the full flow rate of coolant leaking through the high pressure containment seal is actively used for purging purposes. No high efficiency sealing is required downstream of the high pressure area, since the coolant leaking through is used for purging or cooling purposes. Since the high pressure containment seal does not need to achieve a full sealing preventing coolant leakage, its axial dimension can be reduced, which makes the overall footprint of the turbomachine smaller. BRIEF DESCRIPTION OF DRAWINGS

[0021] Reference will now be made to the accompanying drawings, in which:

[0022] Figure 1 A cross section of an expander of the present disclosure is shown, along a plane containing the rotation axis of the rotor;

[0023] Figure 2 An enlarged view of the flow path of the expander of Figure 1 is shown;

[0024] Figure 3 An enlarged view of the flow path of the expander in another embodiment is shown; and

[0025] Figure 4 An oxy-fuel combustion circuit comprising an expander according to the present disclosure is shown. DETAILED DESCRIPTION

[0026] To mitigate the drawbacks and limitations of the current technology as outlined above, according to the present disclosure, the cooling or purging process fluid is directly extracted from the first wheel space, i.e. from the wheel space between the first row of stationary vanes and the first row of rotor vanes forming the first expansion stage of the turbomachine. The pressure in the first wheel space is lower than the highest available pressure of the process fluid at the inlet of the turbomachine. Thus, the coolant at the pressure of the first wheel space can be used for cooling the downstream section of the rotor, reducing the overall coolant consumption.

[0027] In the embodiments disclosed herein, a high pressure zone and a low pressure zone are formed around the front shaft portion. In the high pressure zone, there is process fluid at the highest pressure available in the thermodynamic cycle, while the low pressure zone can be fluidly coupled with the first wheel space of the turbine. A seal around the rotor shaft, hereinafter referred to as a high pressure encapsulation seal, separates the high pressure zone from the low pressure zone. Process gas leaks through the high pressure encapsulation seal from the high pressure zone towards the low pressure zone. The high pressure zone is fluidly coupled with the first rotor cavity, and the low pressure zone is fluidly coupled with the second rotor cavity. In the first rotor cavity, the coolant fluid is at a higher pressure than in the second rotor cavity, and the two cavities are separated by a sealing member. Coolant from the first rotor cavity is used to cool or purge more upstream sections of the rotor, which require higher coolant pressure, while coolant from the second rotor cavity is used to cool or purge more downstream sections of the rotor.

[0028] Thus, contrary to the use of cooling and purge systems from the current art that use coolants from different pressure sources, e.g. different compressor stages, in the turbine of the present disclosure, a high pressure coolant and a low pressure coolant are tapped separately from a high pressure zone and a low pressure zone, said zones being arranged around the front shaft portion of the rotor and separated from each other by a high pressure encapsulation seal. The low pressure zone is fluidly coupled with the first wheel space, or forms part of the first wheel space. Thus, process gas that leaks along the front shaft portion through the high pressure encapsulation seal is used to purge the first wheel space and downstream sections of the rotor, while intermediate sections of the rotor, arranged between the first wheel space and the downstream sections of the rotor, are purged with coolant process gas taken from the high pressure zone upstream of the high pressure encapsulation seal.

[0029] In the following description, specific reference is made to expanders, and more specifically to supercritical carbon dioxide (sCO2) expanders, as possible exemplary embodiments of power generation turbines according to the present disclosure. However, it will be understood by the skilled person in the art of turbines that the novel features disclosed herein can also be advantageously utilized in conjunction with the advantages of other power generation turbines, such as expanders using fluids different from carbon dioxide or using carbon dioxide in a non-supercritical state, or such as gas turbines, or in conjunction with the advantages of gas turbine engines comprising a compressor section, a combustor and a turbine section.

[0030] The novel features disclosed herein are especially beneficial for expanders working at high pressures, e.g. where the highest available pressure in the thermodynamic cycle is 50 barA or above, e.g. equal to or higher than 300 barA.

[0031] In some embodiments, the expander 3 comprises an outer casing 41 that houses the combustor 7, e.g. a can combustor, an annular combustor, an annular can combustor (also known as a tubular combustor). The combustor can comprise a plurality of combustion chambers 7A arranged around the axis A-A of the expander 3.

[0032] In other embodiments, not shown, the combustor can be arranged outside of the expander. In another embodiment, the expander can not include a combustor and can be used in a closed thermodynamic cycle in which heat is transferred to a process fluid, for example, through a heat exchanger.

[0033] In some embodiments, the outer casing 41 comprises a main body 41.1 (referred to herein as a high-pressure casing) and a closure 41.2 (referred to herein as a low-pressure exhaust casing).

[0034] The low-pressure exhaust casing 41.2 can be positioned at the discharge side (i.e., rear side) of the expander 3, i.e., opposite the combustor 7 which is located at the front side of the expander 3.

[0035] The high-pressure casing 41.1 and the low-pressure exhaust casing 41.2 can be connected to each other along a plane P which is orthogonal to the rotation axis A-A of the rotor 43 which is supported for rotation in the outer casing 41. Thus, the expander 3 is a vertically split expander. In other embodiments, the expander can be a horizontally split expander comprising a casing comprising two casing portions which are connected to each other along a plane containing the rotation axis A-A of the rotor 43.

[0036] In some embodiments, the low-pressure exhaust casing 41.2 forms a discharge volute or discharge plenum 41.3 through which the exhaust flue gas is discharged from the expander 3.

[0037] Reference numerals 45, 47 indicate bearing arrangements which rotationally support the rotor 43. For example, the bearing arrangement 45 on the side opposite the combustor 7 (i.e., the rear side) can comprise an axial or thrust bearing in combination with a radial bearing, or a bearing having axial-radial bearing capability. The bearing arrangement 47 on the combustor side (i.e., the front side) can comprise a radial bearing. The opposite arrangement is also possible, with the bearing arrangement having axial load capability on the combustor side. The bearing arrangements 45, 47 can be housed in a bearing housing, not shown in detail.

[0038] In some embodiments, the rotor 43 is housed in an inner casing 51 which is fixedly housed in the outer casing 41.

[0039] In embodiments of the expander 3, Figure 1 and Figure 2 In some embodiments, the expander 3 comprises a plurality of stages. By way of example only, Figure 1 and Figure 2The expander of Figure 1 comprises eight stages. However, it will be understood by the skilled person that the novel features disclosed herein can also be beneficial for expanders having a different number of stages, in particular at least two stages or three stages or more. Each stage comprises a fixed row of fixed vanes or blades 53 arranged in an annular row in an outer casing 41. In the exemplary embodiment of Figure 1, the fixed row of blades 53 is housed in an inner casing 51. Each expansion stage further comprises a respective annular row of rotor blades 55 arranged downstream of the respective annular row of fixed blades 53 along an expansion flow path extending in the front-to-back direction from the combustor 7 through the plurality of expansion stages of the expander to the discharge plenum 41.3. In particular, each annular row of fixed blades of the i-th stage is denoted by 53.i, and each annular row of rotor blades of the i-th stage is denoted by 55.i, with i = 1 to 8 in the exemplary embodiment of Figure 1. In the present document, the reference 53 is used to denote a generic annular row of fixed blades or an individual fixed blade. Accordingly, the reference 55 is used to denote a generic annular row of rotor blades or an individual rotor blade. Figure 1

[0040] In some embodiments, the first (i.e. the most upstream) annular row of fixed blades 53.1 can be arranged at the discharge end of the combustor 7 and forms a series of nozzles guiding the hot, high-pressure process fluid from the combustion chamber 7A of the combustor 7 to the first annular row of rotor blades. The first annular row of rotor blades 55.1 can be arranged directly downstream of the first annular row of fixed blades 53.1. The last (i.e. the most downstream) annular row of fixed blades 53.8 can be positioned in the vicinity of the discharge plenum 41.3 upstream of the last (i.e. the most downstream) annular row of rotor blades 55.8.

[0041] The rotor blades 55 form part of the rotor 43, i.e. are connected to the rotor for co-rotation with the rotor shaft. In embodiments, each annular row of rotor blades 55 (i.e. each row 55.i with i = 1 to 8 in the exemplary embodiment shown) is mounted on a respective rotor disc. The rotor discs are denoted by 57.i with i = 1 to 8. The reference 57 denotes a generic rotor disc.

[0042] The unit consisting of a rotor disc 57 and the respective annular row of rotor blades 55 is also referred to herein as a rotor wheel and is denoted by 58, with 58.1 (i.e. 58.1.1 to 58.1.8) being the most upstream, i.e. the first in the front-to-back direction, rotor wheel; and 58.8 (i.e. 58.8.1 to 58.8.8) being the most downstream, i.e. the last in the front-to-back direction, rotor wheel. Figure 2

[0043] Each rotor blade 55 of a stage can be manufactured separately from the respective rotor disc 57 and mechanically mounted on the rotor disc, as shown in Figure 1. Alternatively, each rotor blade 55 of a stage can be integrally formed with the respective rotor disc 57, as shown in Figure 2. Figure 1 Figure 2 ​​​As illustrated schematically. In other embodiments, the rotor blades 55 and rotor disk 57 of each stage may be manufactured as an integral body, for example, by additive manufacturing. In another embodiment, two design options may be combined. One or more stages may include corresponding integrally manufactured components, including rotor blades and disks, and one or more stages may include rotor disks and separately manufactured rotor blades mechanically coupled to the rotor disks.

[0044] In some implementations, the rotor disks 57 are stacked together and connected to each other by tie rods. Figure 1 and Figure 2 In an exemplary embodiment, the tie rod includes a plurality of tie rods 61 arranged at a distance from the axis of rotation AA and a central tie rod 63 coaxial with the rotor 43.

[0045] In other embodiments, different tie rod arrangements may be provided, such as only a single central tie rod coaxial with rotor 43, or only a set of tie rods arranged around axis AA and radially distanced from it. In yet another embodiment, tie rods at different distances from the rotation axis AA may be provided.

[0046] In some embodiments, rotor 43 further includes a front axle portion 65 and a rear axle portion 67. Each of the front axle portion 65 and the rear axle portion 67 may include one or more sections connected to each other, for example, by a tie rod, as illustrated by the example of the front axle portion 65.

[0047] Although Figure 1 , Figure 2 and Figure 3 In the illustrated embodiment, all rotor blades are mounted on rotor disks, and the rotor disks are stacked on top of each other between the front shaft portion 65 and the rear shaft portion 67. However, in other embodiments not shown, one or more annular rows of rotor blades may be directly mounted on (or integrally manufactured with) the front shaft portion and / or one or more annular rows of rotor blades may be directly mounted on (or integrally manufactured with) the rear shaft portion. In some embodiments, the rotor may include front and rear shaft portions connected to each other by tie rods or the like, wherein rotor blades of all stages are either mounted on or on the rear shaft portion (or integrally manufactured with), or partially mounted on and partially mounted on the front and rear shaft portions, without any rotor disks in between.

[0048] In some embodiments, the burner 7 extends around the front axle portion 65. In some embodiments, the exhaust chamber 41.3 extends around the rear axle portion 67.

[0049] In some implementation schemes, see Figure 1 The front axle portion 65 and the rear axle portion 67 are connected to the rotor disk 57 in a stacked configuration via the aforementioned tie rod arrangement.

[0050] In some embodiments, each rotor disk 57 includes front teeth on both its forward and rearward sides. The front teeth are configured to torsional engage adjacent components of the rotor 43. Figure 1 and Figure 2 In one embodiment, the upstream rotor disk 57.1 engages the front shaft portion 65 on the forward side, and the downstream rotor disk engages the rear shaft portion 67 on the rearward side.

[0051] In some embodiments, corresponding sealing discs 68 (also referred to as spacer discs or spacers) are positioned between each pair of consecutive (i.e., adjacent) rotor discs 57. If the sealing discs 68 are distributed between the pairs of rotor discs 57, front teeth are provided on the opposite side of each sealing disc 68, and the consecutively arranged rotor discs 57 are torsionally connected to each other by the inserted sealing discs 68, forming a Hirth joint between the opposite side of each rotor disc 57 and the corresponding sealing disc 68.

[0052] As used herein, “torsional connection” refers to a connection suitable for transmitting torque between torsional connected components, such that the torsional connected components rotate as a single entity about the rotor’s axis of rotation AA.

[0053] Each sealing disc or spacer 68 is characterized by having an annular seal 68A adapted to cooperate with the radially inward end of the stationary blade 53. In some embodiments, an annular shroud may be provided to connect the radially inward end of the stationary blade, and in this case, the annular seal 68A cooperates with the shroud, but this is not mandatory.

[0054] Although Figure 1 and Figure 2 In one embodiment, the sealing disc or spacer 68 extends radially inward between adjacent rotor discs 57. However, in other embodiments, the rotor discs 57 may be stacked in direct contact with each other and may be provided with corresponding Hirth joint front teeth that transmit torque directly from one rotor disc 57 to the adjacent rotor disc 57. In this case, annular seals may be arranged in conjunction near the feet of the respective rotor blades 55, engaging between adjacent rotor discs, wherein the ends of the fixed blades 53 face radially inward.

[0055] In both cases, the annular seal or sealing disc 68 can seal the radially inward-facing end of the stationary blade to prevent the expanding process fluid from leaking toward the rotor axis from the expansion flow path defined by the staggered stationary blades and rotor blades, which poses a risk of thermal damage to the rotor disc.

[0056] During operation, if the expander 3 operates in an oxygen-fuel cycle, a pressurized process fluid (e.g., a mixture of oxygen and carbon dioxide) is supplied to the burner 7, where it mixes with fuel and burns to produce hot, pressurized process fluid, i.e., hot and pressurized flue gas. This hot flue gas expands along an expansion flow path formed by a series of annular rows of fixed impeller blades and annular rows of rotor blades to generate mechanical power, which is available on the rotor shaft either at the rear end, the front end, or both. This mechanical power can be converted into electricity by a generator and / or used to drive a load, such as a compressor, pump, or other rotating equipment, which drives the shaft coupled to the rotor 43. A gearbox may be arranged along the axis between the expander and the load connected thereto, allowing the load to rotate at a speed different from the expander's rotational speed.

[0057] If the expander does not include a burner and is arranged in a closed thermodynamic cycle, the compressed process fluid can be heated, for example, by heat exchange in a heat exchanger before expansion.

[0058] The cooling or purging process fluid flow is diverted from the main cycle available in the circulation at the highest pressure (i.e., upstream of the expander) and at a lower temperature (i.e., upstream of the burner 7 or the heat exchanger). The cooling process fluid is delivered to the rotor 43 of the expander 3 and extracted from the cavity therein to purge the rotor wheel space and / or to cool the rotor blades, particularly the rotor blades of the most upstream stage. The cooling process fluid prevents or limits leakage of the expanding process fluid from the expansion flow path toward the rotor disk 57, thereby improving the efficiency of expansion and preventing thermal damage to the rotor disk 57. Alternatively, the cooling fluid delivered to the cooling system in the rotor blades (particularly the first stage) prevents thermal damage to them and allows the expander 3 to operate with the process fluid at higher temperatures, thereby improving the efficiency of the thermodynamic cycle.

[0059] To effectively cool or purge rotor 43, according to this disclosure, a novel arrangement for cooling conduits and cavities is provided, which reduces the consumption of process fluids used to achieve the cooling or purging purpose, and improves cooling or purging efficiency, as well as simplifying the structure of the machine.

[0060] Specifically, the expander 3 includes a high-pressure region 71 adjacent to the rotor 43. In some embodiments, the high-pressure region 71 is formed in an annular shape around a portion of the rotor 43. In some embodiments, the high-pressure region 71 surrounds the front shaft portion 65 of the rotor 43. The high-pressure region 71 may be defined on the forward side by a balance drum 72 of the turbine expander.

[0061] High-pressure zone 71 is adapted to be fluidly connected in a location in the fluid path to the upstream process fluid path of burner 7, where, during operation, the process fluid reaches the highest pressure available in the thermodynamic cycle performed by the process fluid. Therefore, in use, high-pressure zone 71 contains process fluid at high pressure. For example, high-pressure zone 71 may be fluidly connected to the delivery side of a process fluid compressor (not shown). The fluid pressure within high-pressure zone 71 is typically slightly higher than the pressure within burner 7 to prevent combustion gases from flowing out of the burner and into high-pressure zone 71.

[0062] The process fluid delivered to the high-pressure region 71 is at a low temperature, that is, close to the temperature of the delivery side of the process fluid compressor.

[0063] The expander 3 also includes a low-pressure region 73 adjacent to the rotor 43. In some embodiments, the low-pressure region 73 extends around the rotor shaft, thereby forming an annular space around it. In some embodiments, the low-pressure region 73 extends around the front shaft portion 65.

[0064] In some embodiments, the low-pressure region 73 includes a first wheel space 73A located between the first stage nozzle (i.e., the fixed blades 53.1 of the first annular row) and the first rotor wheel 58.1, as seen in the front-rear direction.

[0065] Low-pressure regions 73 and 73A are separated from high-pressure region 71 by an annular seal 75, referred to herein as high-pressure sealing seal 75. See [link to document]. Figure 2 It surrounds the rotor shaft, specifically the front shaft portion 65 of the rotor shaft. Specifically, the high-pressure region 71 is located on the side of the high-pressure encapsulation seal 75 facing the front end of the expander 3, and the low-pressure region 73 is located on the side of the high-pressure encapsulation seal facing the rear end of the expander 3.

[0066] Leakage occurs through the high-pressure sealed component 75. Figure 2 The pressure of the process gas (i.e., the pressure in low-pressure region 73) indicated by the arrow fL is lower than the maximum available pressure of the process fluid present in high-pressure region 71. Specifically, in the illustrated embodiment, the pressure in low-pressure region 73, including the first wheel space 73A, is set by expansion occurring in the fixed blades 53.1 of the first annular row. As will become apparent from the following description, the process fluid contained in low-pressure region 73 at a lower pressure is at a pressure sufficient to cool or purge the stages of expander 3 located downstream of the first expander stage.

[0067] Rotor 43 includes a first rotor cavity 77, which is connected to one or more high-pressure coolant conduits 79. Figure 2 It is fluidly connected to the high-pressure region 71. In some embodiments, the first rotor cavity 77 may be coaxial with the rotor axis AA.

[0068] In some embodiments, a plurality of high-pressure coolant conduits 79 are arranged around the axis of rotation AA of the rotor 43. Each high-pressure coolant conduit 79 extends from an inlet end 79.1 fluidly connected to the high-pressure region 71 to an outlet end 79.2 fluidly connected to the first rotor cavity 77.

[0069] exist Figure 1 and Figure 2 In an exemplary embodiment, the first rotor cavity 77 is adapted to provide a coolant flow to at least a second wheel space, the at least second wheel space being between the first rotor wheel 58.1, the second rotor wheel 58.2, and the second row of fixed blades 53.2. Figure 1 and Figure 2 In the implementation plan, arrow C ( Figure 2 The coolant flow shown in the diagram flows from the first rotor chamber 77 into the chamber 81 through slots, holes and / or calibrated channels, which is located between the first rotor wheel 57.1, the second rotor wheel 57.2 and the annular seal 68A of the sealing disc 68 between them.

[0070] Coolant flow C can leak from cavity 81 between the spacer 68 and the mutually facing surfaces of rotor wheels 58.1 and 58.2 to prevent expanding process fluid from flowing into the wheel space and cavity 81 towards rotor disks 57.1 and 57.2.

[0071] For proper purging of the second wheel space and cavity 81 between the first rotor wheel 58.1, the second rotor wheel 58.2, and the stationary blade 53.2 in the second stage, the coolant in the first rotor cavity 77 must be under sufficient pressure to overcome head losses along the coolant passage from the first rotor cavity 77 to the second wheel space. The highest available pressure of the process fluid in the high-pressure region 71 is sufficient to provide a suitable purging coolant flow to the second wheel space. In some embodiments, coolant flow C1 may be provided between the cavity 81 and the cooling system in the rotor blades 55.1 of the first rotor wheel 58.1.

[0072] The first rotor cavity 77 extends axially from the front shaft portion 65 to the intermediate rotor disk 57. Figure 1 and Figure 2 In the illustrated embodiment, the first rotor cavity 77 extends upward to the second rotor disk 57.2 of the second rotor wheel 58.2. In other embodiments, the first rotor cavity 77 may have a greater axial extension and may terminate at a third rotor disk 57.3 or a fourth rotor disk 57.4, for example, as shown in another embodiment below.

[0073] The rotor 43 also includes a second rotor cavity 83 that extends along the rotation axis AA from the front shaft portion 65 toward the rear shaft portion 67. The second rotor cavity 83 may be coaxial with the rotation axis AA and may surround the tie rod 63.

[0074] The second rotor cavity 83 is fluidly separated from the first rotor cavity 77 by a sealing member 85. In some embodiments, the sealing member 85 may have an approximately cylindrical shape and may extend from the front shaft portion 65 to the second rotor disk 57.2 in a manner coaxial with the axis of rotation AA of the rotor 43 (or to another more downstream rotor disk if the first rotor cavity 77 extends further downstream of the second rotor disk 58.2, as described above).

[0075] The second rotor cavity 83 is fluidly connected to the low-pressure region 73 and therefore to the first wheel space 73A, which forms part of the low-pressure region 73. Low-pressure coolant flows into the first wheel space 73A (arrow f73). Figure 2 And flows into the second rotor cavity 83 through one or more low-pressure coolant conduits 87 extending from the low-pressure region 73 to the second rotor cavity 83. The low-pressure coolant conduits 87 may extend radially, such as Figure 1 and Figure 2 As shown, or it may be inclined relative to the radial direction. The low-pressure coolant flow through conduit 87 is illustrated by arrow f87, see [reference]. Figure 2 .

[0076] Therefore, a coolant flow with a pressure lower than the highest available pressure in the cycle is delivered into the second rotor chamber 83 (see arrow f83) and the first wheel space 73A. As mentioned, the pressure in the low-pressure region 73, including the first wheel space 73A, is set by expansion occurring in the stationary blades 53.1 of the first annular row. Depending on the value of said pressure, the first rotor chamber 83 may further extend downstream of the second rotor wheel 58.2, as mentioned.

[0077] Specifically, each low-pressure coolant conduit 87 has an inlet end 87.1 and an outlet end 87.2, the inlet end being in a radially outward position in the low-pressure region 73 and the outlet end being in a radially inward position in the second rotor cavity 83.

[0078] In some implementation schemes, such as Figure 2 As shown, the outlet end 87.2 of each low-pressure coolant conduit 87 is positioned radially inward relative to the outlet end 79.2 of each conduit 79. In other words, the distance between the outlet end 87.2 of each low-pressure coolant conduit 87 and the rotor axis AA is less than the distance between the outlet end 79.2 of each high-pressure coolant conduit 79. Therefore, the low-pressure coolant conduits 87 and the high-pressure coolant conduits 79 intersect each other.

[0079] existFigure 1 and Figure 2 In one embodiment, the pressure of the coolant in the second rotor cavity 83 is sufficient to cause the coolant to purge at least some of the wheel space downstream of the second rotor wheel 58.2. Figure 1 and Figure 2 In the illustrated embodiment, coolant under the pressure of low-pressure region 73 is extracted from the second rotor cavity 83 and used to purge the wheel space downstream of the downstream wheel space cooled by coolant from the first rotor cavity 77. In the illustrated embodiment, coolant from the second rotor cavity 83 is used to purge and / or cool the wheel space from the second rotor wheel 58.3 to the last rotor wheel 58.8.

[0080] Generally, the first rotor cavity 77 is fluidly connected to the uppermost wheel space of the first group, and the second rotor cavity 83 is fluidly connected to the second group of wheel spaces, which are downstream of the uppermost wheel spaces of the first group. Although in Figure 1 and Figure 2 In one embodiment, the first set of uppermost wheel spaces includes only the wheel space between the first (i.e., uppermost) rotor wheel 58.1 and the second rotor wheel 58.2, but in other embodiments, one or more of the subsequent wheel spaces may also be purged by coolant process fluid from the first rotor cavity 77.

[0081] In other words, in some implementations, for example, depending on the pressure in the first wheel space 73A, the first rotor cavity 77 may extend further downstream, and the high-pressure coolant delivered therein may be used to purge the wheel space downstream of the rotor blades 55.2 of the second annular row.

[0082] The coolant from the second rotor cavity 83 can also be used to cool the rotor blades 55 of one or more rotor wheels downstream of rotor wheel 58.1.

[0083] Due to the above arrangement, the separate high-pressure coolant flow (arrow f79, Figure 2 ) and low-pressure coolant flow (arrow f87, Figure 2 The coolant is delivered at different pressure levels in the first rotor chamber 77 and the second rotor chamber 83. Thus, the coolant is delivered for purging and / or cooling purposes at different locations along the expansion flow path of the expander. A lower coolant pressure is available in the second rotor chamber 83 and is sufficient for cooling and purging more downstream expansion stages.

[0084] exist Figure 1 and Figure 2In one exemplary embodiment, the coolant pressure in the second rotor cavity 83 may be approximately the same as the pressure in the first wheel space 73A because there is no sealing arrangement between the first wheel space 73A and the region directly downstream of the high-pressure encapsulation seal 75. In other embodiments, the option of positioning another seal around the rotor between the low-pressure region 73 and the first wheel space 73A is not excluded, such that the coolant pressure in the second rotor cavity 83 is higher than the pressure in the first (i.e., the most upstream) wheel space.

[0085] In some embodiments not shown, the fluid connection between the low-pressure region 73 and the second rotor cavity 83 can be designed such that the pressure in the second cavity 83 is lower than the pressure in the low-pressure region 73. This may be necessary, for example, to reduce the flow rate of the purge cooling fluid flowing from the low-pressure region 73 into the inner cavity 83. This can be achieved, for example, by providing a coolant conduit 87 designed to generate a head loss between the respective inlet 87.1 and outlet 87.2. For example, the diameter of the coolant conduit 87 can be designed to be narrow enough to create the desired pressure drop such that the pressure in the second cavity 83 is lower than (and substantially the opposite of) the pressure in the low-pressure region 73.

[0086] exist Figure 1 and Figure 2 In one embodiment, the first rotor chamber 77 supplies coolant to an upstream section of the rotor and / or to corresponding rotor blades, the upstream section including a second wheel space between rotor wheels 58.1 and 58.2. The second rotor chamber 83 supplies coolant to a downstream section of the rotor, which, in the illustrated embodiment, includes the remaining stages of the expander. However, this is not the only possible arrangement.

[0087] Depending on the required pressure of the coolant in the sequentially arranged expander stages, the first rotor chamber 77 can be designed to provide coolant flow not only to the second wheel space between the first rotor wheel 58.1 and the second rotor wheel 58.2.

[0088] Figure 3 A cross-sectional view of an expander 3 in another embodiment is shown, wherein the upstream section of the rotor includes an additional wheel space. Figure 1 and Figure 2 The same reference numerals in the accompanying drawings are used to indicate the same or equivalent parts described above, and will not be repeated here. Figure 3In this configuration, a first rotor cavity 77 extends from the front axle portion 85 to the third rotor disk 57.3 and supplies coolant or purge fluid to the second and third wheel spaces (i.e., the wheel space between the first rotor disk 58.1 and the third rotor disk 58.3), representing the upstream section of the rotor. A sealing member 85 seals the first rotor cavity 77 apart from a second rotor cavity 83, which supplies coolant at a lower pressure to the downstream section of the rotor.

[0089] In some embodiments, expander 3 may be a CO2 expander for oxygen combustion cycles such as Allam cycle or NET-power thermal cycle.

[0090] Continue to refer to Figure 1 , Figure 2 and Figure 3 , Figure 4 An exemplary power generation system based on an oxygen-fuel thermodynamic cycle is illustrated, in which the expander 3 according to this disclosure can be used. It should be understood that... Figure 4 The system is shown by way of exemplary and non-limiting embodiments, and the novel features disclosed above can be incorporated into expanders or other generators for different thermodynamic cycles.

[0091] The burner 7 of the expander 3 is supplied with an oxidant stream from an oxidant source. The oxidant can be oxygen (O2) or a mixture containing oxygen and carbon dioxide (CO2) or primarily composed of oxygen and carbon dioxide. The oxidant stream can be generated by an air separation unit 9, which is characterized by the oxidant source. The air separation unit 9 can remove nitrogen or nitrogen and carbon dioxide from ambient air to generate the desired oxidant stream, which is supplied to the burner 7 of the expander 3 via an oxidant line 11. In some embodiments, for easier handling of the oxidant stream, the oxidant stream may contain approximately 20% by volume oxygen and 80% by volume carbon dioxide. The percentages of CO2 and O2 mentioned above are exemplary. Carbon dioxide can be added to the oxygen via a recirculation line 12, as explained in more detail below.

[0092] Reference numeral 13 indicates a fuel supply line, for example adapted to supply natural gas (such as methane) to burner 7, particularly to each combustion chamber 7.1. Oxidant and fuel are supplied to burner 7 at high pressure at the inlet side of expander 3.

[0093] The oxidizer fuel blend is burned in burner 7. The pressurized hot combustion gases produced by combustion expand through the flow path of expander 3, and the exhaust gas is discharged after expanding in exhaust line 15 on the exhaust side of expander 3.

[0094] Figure 4The circuit also includes a regenerative heat exchanger 17, in which hot flue gas flowing through the hot side 17.1 of the regenerative heat exchanger 17 is cooled in heat exchange with quenched flue gas flowing through the cold side 17.2 of the regenerative heat exchanger 17. The flue gas discharged from the hot side 17.1 of the regenerative heat exchanger 17 is further quenched in a quench heat exchanger 19 to a temperature at which the vapor contained in the discharged flue gas condenses. Condensate is removed from the discharged flue gas in a water / gas separator 21.

[0095] The dehydrated and chilled flue gas, mainly or solely composed of carbon dioxide, is compressed in the flue gas compressor 23 to the pressure at the inlet side of the expander 3. The pressure at the outlet side of the compressor 23 is the highest pressure of the thermodynamic cycle including the expander 3.

[0096] Compressed flue gas delivered by flue gas compressor 23 is partially removed from the circulation via discharge line 25. If compressor 23 is characterized by multiple compressor turbines arranged in series, discharge line 25 may be connected between two sequentially arranged turbines and / or at the discharge side of the most downstream compressor turbine.

[0097] The remaining compressed flue gas is conveyed through the cold side 17.2 of the regenerative heat exchanger 17 and heated by exchanging heat with the hot flue gas flowing through the hot side 17.1 of the regenerative heat exchanger 17, and then recirculated to the expander 3 via the recirculation line 25. The flue gas recirculated via the recirculation line 25 is mixed with the combustion gases generated in the burner 7, or with the oxidant stream from the oxidant line 11.

[0098] The mechanical power generated by the expansion of combustion gases in expander 3 can be used for mechanical drive or power generation at the output shaft end 31. Figure 4 In an exemplary embodiment, the output shaft end 31 is directly connected to or driven to the generator 33 via a gearbox, connector, or a combination thereof.

[0099] The lateral flow of quenched flue gas at the highest pressure of the thermodynamic cycle is delivered to the expander 3 via cooling line 27, which bypasses the regenerative heat exchanger 17. Cooling line 27 is fluidly connected to the high-pressure region 71 of the expander 3 and provides a coolant flow that is distributed as described above to the first rotor chamber 77, the low-pressure region 73, and the second rotor chamber 83.

[0100] refer to Figures 1 to 3 The novel features of the described coolant distribution system can also be used in gas turbine engines.

[0101] Exemplary embodiments have been disclosed above and illustrated in the accompanying drawings. Those skilled in the art will understand that various changes, omissions, and additions may be made to the specific disclosure herein without departing from the scope of the invention as defined in the following claims.

Claims

1. A power generation turbine, the power generation turbine comprising: Casing (41, 51); Multiple annular rows of fixed blades (53) are arranged in the housing; A rotor (43) is housed in the housing for rotation about a rotor axis (AA); the rotor includes: a rotor shaft having a front shaft portion 65 and a rear shaft portion 67; and a plurality of annular rows of rotor blades (55); wherein a fixed blade (53) of each annular row and a rotor blade (55) of the annular row downstream thereof form a corresponding turbine stage; wherein the turbine stage defines an expansion flow path in the longitudinal direction from the upstream stage to the downstream stage; High-voltage region (71), which is adjacent to the front axle portion (65); Low-pressure region (73), which is adjacent to the front axle portion (65); A high-pressure encapsulation seal (75) surrounds the front axle portion and has a forward side and a rearward side; wherein the high-pressure encapsulation seal (75) separates the high-pressure region (71) and the low-pressure region (73) from each other; and wherein the high-pressure region (71) is located on the forward side of the high-pressure encapsulation seal (75), and the low-pressure region (73) is located on the rearward side of the high-pressure encapsulation seal (75); A first rotor chamber (77) is fluidly connected to the high-pressure region (71) and is adapted to provide a high-pressure coolant flow to the upstream section of the rotor; A second rotor chamber (83), which is fluidly connected to the low-pressure region (73) and adapted to provide a low-pressure coolant flow to a downstream section of the rotor; and A sealing member (85) is housed in the rotor and separates the first rotor cavity (77) from the second rotor cavity (83); The low-pressure region (73) includes a first wheel space (73A) arranged between the fixed blades (53.1) of the first annular row and the rotor blades (55.1) of the most upstream first annular row; and wherein, in use, coolant leaking from the high-pressure region (71) to the low-pressure region (73) through the high-pressure encapsulation seal (75) flows in the low-pressure region, in the first wheel space (73A) and in the second rotor cavity.

2. The power generation turbine according to claim 1, comprising: At least one high-pressure coolant conduit (79) fluidly connects the high-pressure region (71) to the first rotor cavity (77), the at least one high-pressure coolant conduit (79) having an inlet end (79.1) at the high-pressure region (71) and an outlet end (79.2) at the first rotor cavity (77), the outlet end (79.2) being a first distance from the rotor axis (AA); At least one low-pressure coolant conduit (87) fluidly connects the low-pressure region (73) to the second rotor cavity (83), the at least one low-pressure coolant conduit (87) having an inlet end (87.1) at the low-pressure region (73) and an outlet end (87.2) at the second rotor cavity (83), the outlet end being a second distance from the rotor axis (AA); wherein the second distance is less than the first distance.

3. The power generation turbine according to claim 2, wherein, The outlet end (79.2) of the at least one high-pressure coolant conduit (79) is positioned at a distance from the rotor axis (AA) that is less than the distance from the inlet end (87.1) of the at least one low-pressure coolant conduit (87) to the rotor axis (AA).

4. The power generation turbine according to any one of the preceding claims, wherein, In use, the coolant in the first round space and the coolant in the low-pressure region are at approximately the same pressure.

5. The power generation turbine according to any one of the preceding claims, wherein, The upstream section of the rotor includes at least one of the following: rotor blades (55) of the first annular row; a first rotor wheel (57.1); and a second wheel space located downstream of the first wheel space in the front-back direction.

6. The power generation turbine according to any one of the preceding claims, wherein, The downstream section of the rotor includes at least one of the following: a rotor wheel (57) downstream of the upstream section of the rotor; Rotor blade (55), the rotor blade being downstream of the upstream section; Wheel space, the wheel space being located downstream of the upstream segment in the front-rear direction.

7. The power generation turbine according to any one of the preceding claims, wherein, The first rotor cavity (77) is coaxial with the second rotor cavity (83) and is arranged radially outward therefrom.

8. The power generation turbine according to claim 7, wherein, The sealing member (85) is positioned between the first rotor cavity (77) and the second rotor cavity (83) and is coaxial with the first rotor cavity and the second rotor cavity.

9. The power generation turbine according to any one of the preceding claims, wherein, The second rotor cavity (83) surrounds the central tie rod (63), which connects the front shaft portion (65) and the rear shaft portion (67) to each other.

10. The power generation turbine according to any one of the preceding claims, wherein, The sealing component (85) includes a hollow cylindrical body, which is coaxial with the rotor (43).

11. The power generation turbine according to any one of the preceding claims, the power generation turbine further comprising a balance drum (72) torsionally coupled to the rotor shaft; and wherein, The high-pressure area (71) is defined on its forward side by the balancing drum (72).

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