Rotor for a power-generating turbomachine, turbomachine equipped with said rotor, and thermodynamic circuit using said turbomachine

Abstract

The rotor includes multiple rotor discs that are stacked and connected to each other by multiple tie rods. The tie rods comprise at least a first tie rod arrangement and a second tie rod arrangement. The first tie rod arrangement includes multiple first tie rods parallel to the rotor's axis of rotation at a first distance. The second tie rod arrangement may include a set of tie rods arranged parallel to the rotor's axis of rotation at a second distance shorter than the first distance. Alternatively, or in combination, the second tie rod arrangement may include a central tie rod coaxial with the axis of rotation.

Description

Technical Field

[0001] The present disclosure relates to a gas expander particularly adapted for use in an oxygen fuel power cycle operating with a high-pressure process gas, such as a CO2 cycle like the Allam cycle, also known as the NET Power cycle. More generally, the present disclosure relates to a rotor for turbomachinery and a turbomachinery including the rotor.

Background Art

[0002] Fossil fuels are the main source of chemical energy used for the generation of mechanical power. Fossil fuels mix with air and burn to produce high-pressure and high-temperature combustion gases, which expand in a turbine or an expander. The expander converts the enthalpy of the combustion gases into mechanical power available at the output shaft of the expander, and is used to drive loads such as compressors or compressor trains, or to rotate a generator to convert mechanical power into electric power.

[0003] One of the main concerns regarding the combustion of fossil fuels relates to the production of carbon dioxide, a greenhouse gas considered to be one of the main factors of global warming and climate change.

[0004] To reduce the environmental impact of power generation by the combustion of fossil fuels, options for post-combustion capture of carbon dioxide have been investigated. Carbon dioxide capture facilities have been developed to treat flue gases discharged from gas turbines and remove carbon dioxide from the flue gases before discharging the flue gases into the environment. The cost of carbon dioxide capture facilities is high both in terms of CAPEX and in terms of the energy required to operate the facilities, and reduces the overall thermodynamic efficiency of the system. The proportion of carbon dioxide in the flue gases is low. This requires a large amount of flue gases to be processed through the carbon dioxide capture facilities, making the capture process particularly inefficient.

[0005] In recent years, the oxygen combustion cycle, also known as the oxygen fuel cycle, has been developed, in which a fuel such as natural gas or another fossil fuel is mixed under high pressure with an oxidizer mixture consisting mainly of oxygen (O2) and carbon dioxide (CO2). The mixture of fuel, oxygen, and carbon dioxide is burned in the combustor of the expander to produce pressurized flue gas consisting only of carbon dioxide and water, or almost entirely of carbon dioxide and water.

[0006] The flue gas is expanded in the expander to generate mechanical power. The exhaust flue gas discharged from the expander's outlet is cooled in a regenerative heat exchanger, further lowered to a low temperature, and condensed into water, which can be removed from the cooled flue gas. The low-temperature flue gas, consisting mainly or exclusively of carbon dioxide, is pressurized and recirculated through the regenerative heat exchanger towards the combustor of the expander.

[0007] The oxygen supplied to the combustor of the expander can be obtained by separating it from the ambient air and removing nitrogen, and the working fluid supplied to the combustor consists mainly of oxygen and carbon dioxide, and does not contain nitrogen. The resulting flue gas consists mainly of water and carbon dioxide. Water is removed from the flue gas by condensation, and a portion of the water-free flue gas that is not recirculated to the combustor can be efficiently processed in a carbon dioxide capture unit.

[0008] The oxygen-fueled cycle summarized above is a semi-closed cycle in that only a portion of the flue gas leaves the cycle after the water has been removed from it.

[0009] The oxygen-fueled or oxygen-combustion cycles described above are particularly interesting in terms of efficiency and reduction of harmful emissions. However, they operate under supercritical CO2 conditions at the expander inlet and are characterized by a high pressure drop across the expander and high torque applied to the expander rotor. These factors become important and significant challenges in the design of the expander rotor as the expander's power rating increases, potentially limiting the maximum power factor of the expander.

[0010] For example, the design of novel rotors and turbomachines adapted to achieve higher power rates in the oxygen fuel cycle would be welcomed in the art. [Overview of the project]

[0011] In one embodiment, rotors for power generation turbomachinery, for example, in particular for expanders or turbo expanders, are disclosed herein. In some embodiments, the expander is, for example, an oxygen-fuel combustion expander adapted to handle supercritical carbon dioxide at the expander inlet.

[0012] In embodiments disclosed herein, the rotor includes a plurality of rotor discs stacked and connected to one another by a plurality of tie rods. Each disc includes a plurality of rotor blades arranged in an annular row around the rotor's axis of rotation. The rotor blades constitute part of the expansion passage of the power-generating turbomachinery when the rotor is placed in a turbomachinery. The tie rods include at least a first tie rod array and a second tie rod array. The first tie rod array includes a plurality of first tie rods parallel to the rotor's axis of rotation at a first distance. The second tie rod array may include a set of tie rods arranged parallel to the rotor's axis of rotation at a second distance shorter than the first distance. Alternatively, or in combination, the second tie rod array includes a central tie rod coaxial with the axis of rotation.

[0013] The double tie rod arrangement provides a strong axial coupling between the rotor components. This axial coupling is adapted to withstand the high torque and pressure typically present in supercritical carbon dioxide power generation turbomachinery, such as expanders for oxygen fuel or oxygen combustion cycles. Similar tie rod arrangements can be used in other situations where torque and / or pressure conditions are critical.

[0014] The rotor further includes a front shaft portion and a rear shaft portion. A set of rotor discs is positioned between the front shaft portion and the rear shaft portion. Each tie rod of the first tie rod array extends from the front shaft portion to the rear shaft portion and engages with the front shaft portion and the rear shaft portion.

[0015] Further embodiments and features of the rotor are described in the appended claims and are described below.

[0016] In a further embodiment, this specification discloses a power-generating turbomachine including the rotor outlined above. In embodiments disclosed herein, the turbomachine may be an expander, and may be a supercritical CO2 expander, i.e., an expander in which carbon dioxide is in a supercritical state at the inlet of the expansion channel, and / or an expander for an oxygen-fuel combustion cycle such as an Aram cycle.

[0017] In a further aspect, this specification discloses a thermodynamic circuit using a turbomachine in the form of an expander, as outlined above and described in more detail in the following description of exemplary embodiments. [Brief explanation of the drawing]

[0018] Here, we will briefly refer to the attached diagram. [Figure 1] This is a schematic diagram of an oxygen fuel power circuit. [Figure 2] This is a cross-sectional view along the expander according to the first embodiment of the present disclosure. [Figure 3] This is a cross-sectional view of the rotor for the expander shown in Figure 2, according to one embodiment. [Figure 4] This is a cross-sectional view of a rotor for an expander according to the present disclosure in a further embodiment. [Figure 5] This is a cross-sectional view of a rotor for an expander according to the present disclosure in yet another embodiment, following the line VV in Figure 7. [Figure 6] This is a cross-sectional view following the line VI-VI in Figure 7. [Figure 7]A cross-sectional view taken along line VII-VII of FIGS. 5 and 6.

DETAILED DESCRIPTION OF THE INVENTION

[0019] The schematic diagram of FIG. 1 shows a simplified supercritical carbon dioxide cycle (abbreviated as sCO2 cycle), such as an Allam cycle or a similar oxygen-fuel combustion cycle, where the use of an expander including a rotor according to the present disclosure can be particularly beneficial. Generally, the supercritical carbon dioxide cycle as understood herein is a cycle in which carbon dioxide is in a supercritical state at at least the inlet of the expansion flow path in the expander.

[0020] The power system 1 shown in FIG. 1 includes an expander 3 (also known as a turboexpander) including an expansion section 5 and a combustor 7. The combustor 7 can be, for example, an annular combustor, a can-type combustor, a can-annular combustor, etc. In the current preferred embodiment, the combustor is a can-type combustor having a plurality of combustion chambers arranged around the rotation axis of the expander 3, as shown in more detail in FIG. 2. In some embodiments, as schematically shown in FIG. 2, the combustion chambers are housed within the high-pressure casing of the expander, as will be described in more detail below. In some embodiments, each combustion chamber is housed within a respective sheet configured within the high-pressure casing of the expander, as will be described in more detail below.

[0021] Reference numeral 7.1 in FIG. 2 indicates a single combustion chamber of a can-type or can-annular combustor. In other embodiments, not shown, the combustor may be an annular combustor as described above.

[0022] The combustor 7 is supplied with an oxidant stream supplied by an oxidant source. The oxidant may be a mixture containing oxygen (O2) or oxygen and carbon dioxide (CO2), or mainly consisting of these. The oxidant stream can be generated by an air separation unit 9 having an oxidant source. The air separation unit 9 can remove nitrogen or nitrogen and carbon dioxide from ambient air to generate the necessary oxidant stream supplied to the combustor 7 of the expander 3 through the oxidant line 11. In some embodiments, the latter can contain about 20% by volume of oxygen and 80% by volume of carbon dioxide for easier handling of the oxidant stream. The above ratios of CO2 and O2 are examples. Carbon dioxide can be added to oxygen through the recirculation line 12 as will be described in detail below.

[0023] Reference numeral 13 indicates a fuel supply line adapted to supply natural gas, such as methane, to the combustor 7, specifically to each combustor chamber 7.1. The oxidant and fuel are supplied to the combustor 7 at high pressure from the inlet side of the expander 3. The upper limit pressure of the thermodynamic cycle can be, for example, 50 barA or more, preferably 100 barA or more, for example about 200 barA or more, preferably about 250 barA or more, or higher, for example 300 barA or more. Generally, the pressure can be less than 800 barA, or less than 650 barA. In some embodiments, the upper limit pressure of the thermodynamic cycle, that is, the pressure in the combustor and at the first expansion stage, can be 100, 150, 200, 250, 300, or 350 barA.

[0024] The mixture of oxidant and fuel is burned in the combustor 7. The pressurized high-temperature combustion gas resulting from the combustion expands in the expansion section 5 of the expander 3. The temperature at the outlet side of the fixed nozzle downstream of the combustor can be included, for example, between 800°C and 1500°C.

[0025] The exhausted flue gas, after expansion, is discharged into the discharge line 15 on the discharge side of the expander 3. The flue gas in the discharge line 15 may have a temperature of approximately 400°C to approximately 700°C, for example, approximately 600°C, and a pressure of approximately 10 barA to approximately 100 barA, preferably in the range of approximately 20 barA to approximately 60 barA.

[0026] The circuit further includes a regenerative heat exchanger 17, in which the high-temperature flue gas flowing through the high-temperature side 17.1 of the regenerative heat exchanger 17 is cooled by heat exchange with the flow of cooled flue gas flowing through the low-temperature side 17.2 of the regenerative heat exchanger 17. The flue gas discharged from the high-temperature side 17.1 of the regenerative heat exchanger 17 is further cooled in a cooling heat exchanger 19 to a temperature that causes condensation of the vapor contained in the discharged flue gas. The condensed water is removed from the exhausted flue gas in a water / gas separator 21.

[0027] The dewatered, exhausted, and cooled flue gas, consisting mainly or exclusively of carbon dioxide, is compressed in the flue gas compressor 23 to the pressure at the inlet of the expander 3. In the schematic diagram of Figure 1, the flue gas compressor 23 is shown as a single compressor, but in some embodiments, multiple compressors may be used. For example, the flue gas compressor 23 can be a multi-stage compressor or a compressor train. In some embodiments, the compressor may be an intercooled compressor. In some embodiments, the main compressor may be set in series with two successively arranged pumps.

[0028] The compressed flue gas supplied by the flue gas compressor 23 is partially removed from the cycle through the discharge line 25. If the compressor 23 is characterized by multiple compression turbomachines arranged in series, the discharge line 25 may be connected between two consecutively arranged turbomachines and / or to the discharge side of the furthest downstream compression turbomachine.

[0029] The remaining compressed flue gas is sent through the low-temperature side 17.2 of the regenerative heat exchanger 17, heated by heat exchange with the high-temperature flue gas flowing through the high-temperature side 17.1 of the regenerative heat exchanger 17, and recirculated to the expander 3 through the recirculation line 25. The flue gas recirculated through the recirculation line 25 is mixed with the combustion gas generated in the combustor 7 or with the oxidizer stream from the oxidizer line 11.

[0030] The sidestream of cooled flue gas is sent through a cooling line 27 that bypasses the regenerative heat exchanger 17 towards the components of the expander 3 that require cooling.

[0031] The expander 3 may include an output shaft end 31 that can be integrated with the central portion of the rotor, or assembled to the central portion of the rotor by bolting, welding, hearth or spline connection, or a combination thereof. The mechanical power generated by the expansion of the combustion gases in the expansion section 5 of the expander 3 is available at the output shaft end 31 for mechanical drive or power generation purposes. In the exemplary embodiment of Figure 1, the output shaft end 31 is driven and coupled to the generator 33 directly or via a gearbox, joint, or a combination thereof. The flange connection between the output shaft end 31 and the generator 33 is shown at 49 in Figure 2. The generator 33 is electrically coupled to the power distribution network 35. In Figures 1 and 2, the output shaft end 31 is shown on the rear side of the expander 3. In other embodiments, not shown, the output shaft end 31 may be located on the front side of the expander. In yet another embodiment, not shown, two output shaft ends may be provided, one on the front side of the expander and the other on the rear side.

[0032] As used herein, “forward” and “rear” refer to the direction of the process gas flow through the expander 3. Therefore, “forward” refers to the position on the combustor 7 side, and “rear” refers to the position on the opposite side of the combustor 7, i.e., the exhaust side of the expander 3.

[0033] The high pressure drop across the expander 3, the high absolute pressure in the combustor 7 and the cooling duct of the expander, and the high torque on the expander shaft present significant challenges to the design of the expander 3, particularly in the case of high rated powers such as 150 MW or around that, or above, for example, 100 MW to 2000 MW. The expander, specifically the rotor designs disclosed herein, can be used to achieve high power factors of the order of 50 MW or higher, for example, 100 MW or higher, for example, 150 MW or higher, for example, 200 MW or higher, or 300 MW or higher. In embodiments, the rated power can be lower than 2000 MW, preferably lower than 1500 MW, for example, lower than 1000 MW, or lower than 800 MW. For example, the rated power may fall between 200 MW and 650 MW. The intermediate values ​​of the upper and lower limits of each of the above ranges are also expressly disclosed herein.

[0034] Continuing with the reference to Figure 1, Figure 2 shows a cross-sectional view of the expander 3 in one embodiment. As an example, the expander in Figure 2 includes the rotor according to Figure 4. In other embodiments, the expander in Figure 2 may include the rotor according to Figure 3 or Figures 5, 6, and 7, as will be disclosed in more detail below.

[0035] In some embodiments, the expander 3 comprises an outer casing 41 housing the combustor 7. In some embodiments, the outer casing 41 includes a body 41.1, referred herein as the high-pressure casing, and a closure 41.2, referred herein as the low-pressure exhaust casing. The high-pressure casing 41.1 may be monolithic, i.e., it may include a body consisting of a single piece manufactured, for example, by forging, machining, casting, or a combination thereof. In some embodiments, the high-pressure casing 41.1 may be manufactured by welding together a plurality of components joined along a plane perpendicular to the axis of rotation, preferably.

[0036] The low-pressure exhaust casing 41.2 can be positioned on the exhaust side of the expander 3, i.e., the rear side, i.e., opposite to the combustor 7. The low-pressure exhaust casing 41.2 may be monolithic, i.e., it may consist of a single part manufactured by, for example, forging, machining, casting, or a combination thereof. In some embodiments, the low-pressure exhaust casing 41.2 can be manufactured from two or more components that can be irreversibly connected to each other, for example by welding, or reversibly joined to each other, for example by bolts. For example, the low-pressure exhaust casing 41.2 can be separated into two parts along a plane containing the axis of rotation of the expander.

[0037] The high-pressure casing 41.1 and the low-pressure exhaust casing 41.2 can be connected to each other along a plane P perpendicular to the axis of rotation AA of the rotor 43, which is supported to rotate within the outer casing 41.

[0038] In some embodiments, the low-pressure exhaust casing 41.2 constitutes an exhaust volute or exhaust plenum 41.3 through which the exhausted flue gas is discharged from the expander 3.

[0039] Reference numerals 45 and 47 indicate bearing devices that rotatably support the rotor 43. For example, the bearing device 45 on the opposite side of the combustor 7, i.e., the rear side, may include an axial bearing or thrust bearing combined with a radial bearing, or a bearing having axial-radial bearing capability. The bearing device 47 on the combustor side may include a radial bearing. The reverse arrangement is also possible, with a bearing having axial load capacity located on the combustor side. The bearing devices 45 and 47 can be housed in bearing casings, which are not shown in detail.

[0040] In some embodiments, the rotor 43 is surrounded by one or more inner casings 51 fixedly housed within an outer casing 41. Each inner casing 51 can be divided into two parts along a plane parallel to the rotation axis AA of the rotor 43, for example, the plane containing the rotation axis AA. The arrangement of the inner casings 51 and outer casings 41 is particularly beneficial when the combustion gases reach high pressures of about 200 to 300 bar A or higher. The monolithic high-pressure casing 41.1 can withstand the load generated by the high pressure inside the outer casing, while the inner casings 51 facilitate the mounting of fixed vanes or fixed blades, as described below.

[0041] The pressure drop across the expander 3 can be about 150 bar or more, preferably about 200 bar or more, for example, 250 to 400 bar. A number of expansion stages are preferred to expand the combustion gas generated in the combustor 7. In the exemplary embodiments shown in Figures 2 to 7, the expander 3 includes eight stages. In other embodiments, a different number of expansion stages may be assumed, preferably four or more, more preferably five or more. In some embodiments, the number of expansion stages may be more than eight, for example, nine, ten, eleven, or more, and preferably less than fifteen. The expansion stages constitute axial expansion passages for the process gas expanding in the expander 3.

[0042] Each expansion stage includes an annular row of fixed vanes or fixed blades 53 fixedly arranged within the outer casing 41. In the exemplary embodiment shown in Figure 2, the annular row of fixed blades is housed within the inner casing 51. Each expansion stage further includes an annular row of rotor blades 55 positioned downstream of each annular row of fixed blades along an expansion flow path that extends from front to rear through the expansion section 5 from the combustor 7 to the exhaust plenum 41.3.

[0043] In some embodiments, the annular row of the first fixed blades 53.1 may be located at the exhaust end of the combustor 7 and may constitute an array of nozzles that guide high-temperature, high-pressure gas from the combustion chamber of the combustor to the first row of rotor blades. The annular row of the first rotor blades, labeled 55.1, may be located immediately downstream of the annular row of the first fixed blades 53.1 adjacent to the combustor 7. The annular row of the last fixed blades 53.8 may be located upstream of the annular row of the last rotor blades, labeled 55.8, near the exhaust plenum 41.3. Reference numeral 55 refers collectively to any one of the annular rows of rotor blades or to the rotor blades themselves.

[0044] The rotor blades 55 constitute part of the rotor 43, i.e., they are connected to rotate with the rotor shaft. In this embodiment, annular rows of each rotor blade 55 (i.e., each row 55.i, i=1 to 8) are connected to their respective rotor disks. The rotor disks are labeled 57.i, i=1 to 8. Reference numeral 57 indicates a typical rotor disk. Structures of the rotor 43 in different embodiments are shown in Figures 2 to 7.

[0045] More specifically, Figure 4 shows an enlarged view of the rotor shown in Figure 2, and Figure 3 shows an alternative embodiment of a rotor having a similar structure. A modified rotor, described in more detail later, is shown in Figures 5 to 7. In Figures 5 to 7, the rotor blades 55 are omitted for clarity.

[0046] Each rotor blade can be manufactured separately from its respective rotor disk 57 and mechanically mounted thereon. In other embodiments, each rotor blade and rotor disk can be manufactured as a monolithic body, for example, by additive manufacturing. In yet another embodiment, two design options can be combined. One or more stages may include each monolithically manufactured component, including the rotor blades and disks, while one or more stages may include a rotor disk and separately manufactured rotor blades mechanically coupled to the rotor disk.

[0047] The rotor discs 57 are connected to each other by tie rods. In the exemplary embodiments shown in Figures 2 to 4, the tie rods comprise a first tie rod array including a plurality of tie rods 61 and a second tie rod array including a single tie rod 63.

[0048] More specifically, the tie rods 61 of the first tie rod arrangement are positioned at a certain distance from the rotation axis AA of the rotor 43. Preferably, all tie rods 61 are positioned at the same distance d1 from the rotation axis AA of the rotor 41. Preferably, the tie rods 61 are distributed at a constant angular pitch around the rotation axis AA of the rotor 43.

[0049] In these embodiments, a single central tie rod 63 of the second tie rod array is coaxial with the rotor 43.

[0050] In some embodiments, the rotor 43 further comprises a front shaft portion 65 and a rear shaft portion 67. Each of the front shaft portion 65 and the rear shaft portion 67 may include one or more sections connected to each other, for example, by tie rods.

[0051] In some embodiments shown in Figure 2, the combustor 7 extends around the front shaft portion 65. In some embodiments, the exhaust plenum 41.3 extends around the rear shaft portion 67.

[0052] In some embodiments, the front shaft portion 65 and the rear shaft portion 67 are connected to the rotor disc 57 in a stacked configuration by the tie rod arrangement described above.

[0053] More specifically, in the embodiments shown in Figures 2 and 4, the first tie rod 61 of the first tie rod array extends through each through-hole of the rotor disc 57 and includes a first end 61.1 connected to the front shaft portion 65 and a second end 61.2 connected to the rear shaft portion 67. The first end 61.1 and the second end 61.2 of each tie rod 61 are threaded to engage with the respective nuts 62.1 and 62.2.

[0054] In some embodiments, each rotor disc 57 is provided with front teeth on each side for torsional engagement with the respective front teeth of adjacent rotor discs, front shaft portions 65, and / or rear shaft portions 67. The front teeth constitute hearth joints between the rotor discs 57, and between the first and last rotor discs 57.1, 57.8 and the front shaft portions 65 and rear shaft portions 67, respectively.

[0055] In some embodiments, each sealing disc 68, also known as a spacing disc, is positioned between each pair of consecutive (i.e., adjacent) rotor discs 57. When the sealing discs 68 are scattered between pairs of rotor discs 57, each sealing disc 68 is provided with front teeth on both sides, and the consecutively arranged rotor discs 57 are torsion-connected to one another via the interposed sealing discs 68, forming a hearth joint between both sides of each rotor disc 57 and each sealing disc 68. As used herein, the expression “torsion-connected” means a connection adapted to transmit torque between torsion-connected components so that the torsion-connected components rotate as a single unit around the rotor's axis of rotation AA.

[0056] Providing front teeth may be beneficial in increasing the torque that can be transmitted from the front shaft portion 65 to the first rotor disc 57.1, from the last rotor disc 57.8 to the rear shaft portion 67, and between each rotor disc 57 and adjacent rotor discs or sealing discs 68. In some embodiments, front teeth may be provided only in certain sections of the rotor where higher torque is transmitted, i.e., the most downstream section of rotor 43. The region where the highest torque is transmitted depends on where the load is applied, i.e., whether it is on the rear side (opposite side of the combustor 7) or the front side (side of the combustor 7) of the expander 3. Output shafts on both sides (rear and front) may also be foreseen.

[0057] In Figures 2, 3, and 4, the sealing disc or spacer 68 extends radially inward between adjacent rotor discs 57. In other embodiments, the rotor discs 57 may be stacked in direct contact with each other and each may have front teeth on a hearth joint that directly transmit torque from one rotor disc 57 to an adjacent rotor disc 57. In this case, an annular seal runner can be provided between adjacent rotor discs.

[0058] In either case, the seal runner or sealing disc 68 provides a seal to the stationary blades, preventing gas from leaking outside the expansion passage defined by the scattered rows of stationary blades and rotor blades.

[0059] In the exemplary embodiments shown in Figures 2 and 4, the central tie rod 63 has a first threaded end 63.1 extending through a central hole 65.1 in the front shaft portion 65. The central tie rod 63 has a second threaded end 63.2 extending through the disc 57 and screwing into a threaded blind hole 67.2 in the rear shaft portion 67. A nut 71.1 screws onto the first threaded end 63.1 of the central tie rod 63 to axially fasten the front shaft portion 65, the rear shaft portion 67, the eight rotor discs 57.1 to 57.8, and the sealing disc 68 (if present) to each other. In other embodiments, not shown, the rear shaft portion 67 may have a through hole, and the second threaded end 63.2 of the central tie rod 63 may be engaged by a nut similar to nut 71.1.

[0060] The tie rod arrangement described above enhances the axial connection between the components of the rotor 43, thereby enabling the rotor to withstand the high axial thrust generated by the pressure drop across the expander 3 during use.

[0061] The enhanced coupling achieved by the dual tie rod arrangement is also beneficial in that it increases the torque that can be transmitted to the driven shaft via the rotor.

[0062] The double tie rod arrangement has further beneficial effects with respect to rotor cooling. Cooling is performed by supplying pressurized cooling fluid to the rotor 43. Specifically, in some embodiments, compressed and cooled carbon dioxide can be delivered to a cooling chamber 66 inside the rotor 43. For example, pressurized carbon dioxide supplied by the flue gas compressor 23 via the cooling line 27 (Figure 1) can be supplied to the cooling chamber 66, flowing through radial holes (not shown) in the rotor 43, buffering and cooling the space 58 between adjacent disks 57. The double tie rod arrangement can withstand the load generated by the high-pressure cooling carbon dioxide supplied inside the rotor 43.

[0063] In some embodiments, the expander 3 includes a balance drum drivably coupled to the rotor 43. In the embodiments of Figures 2 and 4, the balance drum 75 is located at the front end of the rotor 43, between the first expander stage and the front bearing device 47.

[0064] In some embodiments, the balance drum 75 is integrally formed with the front shaft portion 65.

[0065] In some embodiments, as shown in Figures 2 and 4, the front shaft portion 65 includes two sections 65A and 65B. The two sections 65A and 65B of the front shaft portion 65 may be connected to each other by a single tie rod. Preferably, as shown in Figures 2 and 2A, the two sections 65A and 65B are connected to each other by a plurality of tie rods 77 arranged around the rotation axis AA of the rotor 43. The tie rods 77 extend through holes provided in two flanges 75.1 and 75.2 of the two sections 65A and 65B of the front shaft portion 65, and the flanges 75.1 and 75.2 cumulatively constitute the balance drum 75.

[0066] By dividing the balance drum into balance drum sections 75.1 and 75.2, the manufacturing of the balance drum by, for example, forging becomes easier, and the possibility of assembling and tightening the central tie rod 63 is provided.

[0067] Continuing with references to Figures 2 and 4, a further embodiment of the rotor 43 for the expander 3 is shown in Figure 3. The same reference numerals used in Figures 2 and 4 and in Figure 3 refer to the same or equivalent components, parts, or elements of the rotor 43, which will not be described again.

[0068] The rotor 43 in Figure 3 differs from the rotors in Figures 2 and 4, primarily in that the second threaded end 63.2 of the central tie rod 63 engages with a through hole 64.1 in the inner flange 64, which is integrally formed with the disc 57.6. The nut 71.2 is screwed onto the threaded end 63.2 of the central tie rod 63.

[0069] In this embodiment, the central tie rod 63 contributes to the axial force connecting only some of the rotor discs to each other. Specifically, in the embodiment shown in Figure 3, the central tie rod 63 connects the rotor discs 57.1 to 57.6, the respective sealing discs 68, and the front shaft portion 65 of the rotor 43. This block is then mechanically connected to the remaining discs 57.7, 57.8 and the rear shaft portion 67 by the tie rods 61 of the first tie rod array.

[0070] In the embodiments described above, the second tie rod array includes a single central tie rod 63 coaxial with the rotor 43, but in other embodiments, the second tie rod array may include a plurality of second tie rods, either as replacements for the central tie rod or in combination with the central tie rod. The second tie rods are positioned around and extending parallel to the axis of rotation AA of the rotor 43, just like the tie rod 61 of the first tie rod array.

[0071] Embodiments having a second tie rod arrangement including multiple tie rods are shown in Figures 5, 6, and 7, where Figure 7 is a cross-sectional view of the rotor with respect to a plane perpendicular to the rotation axis AA of the rotor 43. In Figures 5, 6, and 7, the same reference numerals are used to indicate parts, elements, or components that are similar to or correspond to those described in relation to Figures 2, 3, and 4. These parts will not be described again.

[0072] The tie rods of the second tie rod arrangement shown in Figures 5, 6, and 7 are positioned at a distance d2 from the rotation axis AA of the rotor 43. Distance d2 is shorter than distance d1. In the embodiments of Figures 5, 6, and 7, the tie rod 63 extends axially from the front shaft portion 65 to the rear shaft portion 67 and engages with both the front and rear shaft portions. In other embodiments, not shown, the tie rod 63 has a shorter axial length and can engage with the inner flange of one of the rotor discs 57, for example, the sixth rotor disc 57.6, in exactly the same manner as shown in Figure 3.

[0073] Exemplary embodiments are disclosed above and shown in the accompanying drawings. Those skilled in the art will understand that various modifications, omissions, and additions may be made to those specifically disclosed herein without departing from the scope of the invention as defined in the following claims.

[0074] For example, in the embodiments disclosed herein, the combustor is housed in the expander, but in other embodiments, the combustor may be located outside the expander.

[0075] In yet another embodiment, the expander disclosed herein can be used in a closed-loop thermodynamic cycle such as a supercritical carbon dioxide cycle, in which heat is introduced into the thermodynamic cycle via a heat exchanger rather than using a combustor.

[0076] Furthermore, in the illustrated embodiment, the rear shaft portion 67 is manufactured as a monolithic unit, but in other embodiments, the rear shaft portion 67 can be divided into two or more sections in exactly the same manner as the front shaft portion 65. The two portions may be connected to each other by the same tie rod 63. Alternatively, an additional rod, similar to the rod 77, may connect the two sections of the rear shaft portion 67 to each other.

Claims

1. A rotor for a power generation turbomachine, A set of rotor discs, each of which comprises an annular row of rotor blades for the expansion passage of the power-generating turbomachine, and each annular row of rotor blades surrounding the rotation axis of the rotor, The rotor disc set comprises a front shaft portion and a rear shaft portion, and is positioned between the front shaft portion and the rear shaft portion. The front shaft portion, the rear shaft portion, and the rotor disc are stacked and connected to each other by a plurality of tie rods, and the plurality of tie rods are at least A first tie rod arrangement comprising a plurality of first tie rods parallel to the rotation axis of the rotor at a first distance, A second tie rod arrangement is provided, wherein the second tie rod arrangement is (i) A set of tie rods arranged parallel to the rotation axis of the rotor at a second distance shorter than the first distance, or (ii) A central tie rod coaxial with the rotation axis of the rotor, or (iii) A set of tie rods arranged parallel to the rotation axis of the rotor at a second distance shorter than the first distance, and a central tie rod coaxial with the rotation axis of the rotor. Equipped with, Each of the first tie rods extends from the front shaft portion to the rear shaft portion and engages with the front shaft portion and the rear shaft portion, respectively, of the rotor.

2. The rotor according to claim 1, wherein the central tie rod has a first end that engages with the front shaft portion and a second end that engages with the rear shaft portion.

3. The rotor according to claim 1, wherein the central tie rod has a first end that engages with one of the front shaft portion and the rear shaft portion, and the central tie rod has a second end that engages with one of the rotor discs midway between the front shaft portion and the rear shaft portion.

4. The rotor according to claim 3, wherein the first end of the central tie rod engages with the front shaft portion.

5. The rotor according to claim 1, wherein each of the tie rods in the second tie rod arrangement extends from the front shaft portion to the rear shaft portion and engages with the front shaft portion and the rear shaft portion.

6. The rotor according to one or more of claims 1 to 5, further comprising a sealing disc inserted between adjacent rotor discs and twisted together.

7. The rotor according to one or more of claims 1 to 6, wherein at least one of the rotor disks has front teeth adapted to rotatably connect the rotor disk to at least one of an adjacent rotor disk, a front shaft portion, a rear shaft portion, and an adjacent sealing disk, or any combination thereof.

8. A rotor according to one or more of claims 1 to 7, further comprising a balance drum.

9. The rotor according to claim 8, wherein the balance drum is configured as one of the front shaft portion and the rear shaft portion, preferably the front shaft portion.

10. The rotor according to claim 9, wherein the balance drum comprises a first balance drum portion and a second balance drum portion connected to each other via at least one tie rod, preferably via a plurality of tie rods arranged circumferentially around the rotation axis of the rotor.

11. A rotor according to one or more of claims 1 to 10, comprising at least four expander stages, preferably at least five expander stages.

12. The rotor according to one or more of claims 1 to 11, wherein the rotor comprises an axial cooling chamber adapted to receive a cooling fluid and radially fluid-connected to an annular spacer between adjacent disks of the rotor.

13. It is a power generation turbomachine, outer casing and A plurality of annular rows of fixed blades arranged within the casing, A rotor according to any one of claims 1 to 12, housed for rotation within the casing, A power-generating turbomachine comprising, wherein each of the annular rows of rotor blades and the annular row of upstream fixed blades each constitutes an expansion stage of the expansion channel.

14. The turbomachinery according to claim 13, wherein the turbomachinery is a power generation turbomachinery, in particular a gas turbine or an expander.

15. The turbomachinery according to claim 13 or 14, wherein the outer casing comprises a high-pressure casing and a low-pressure exhaust casing, and the high-pressure casing and the low-pressure exhaust casing are coupled along a plane perpendicular to the rotation axis of the rotor.

16. The turbomachinery according to claim 15, wherein the high-pressure casing comprises a monolithic barrel body.

17. The turbomachinery according to claim 15 or claim 16, wherein the low-pressure exhaust casing is configured as a monolithic body.

18. The turbomachine according to any one of claims 13 to 17, further comprising at least one combustor housed within the outer casing.

19. The turbomachinery according to claim 18, wherein, as dependent on claim 16, the at least one combustor is housed in a sheet configured within the high-pressure casing.

20. The turbomachinery according to claim 19, wherein the low-pressure exhaust casing is positioned on the low-pressure side of the expander opposite to the combustor, and the low-pressure exhaust casing constitutes an exhaust plenum.

21. The turbomachinery according to any one of claims 13 to 20, further comprising at least one inner casing, preferably a plurality of inner casings, fixedly housed within the outer casing and surrounding the rotor, wherein each inner casing is divided into a first casing portion and a second casing portion along a plane parallel to the rotation axis of the rotor, and the inner casing comprises an annular row of fixed blades.

22. The turbomachinery according to any one of claims 13 to 21, wherein the rotor is adapted to receive a process gas having a temperature T between 800°C and 1500°C.

23. The turbomachinery according to any one of claims 13 to 22, wherein the rotor is adapted to receive process gas at a pressure higher than 50 barA, preferably higher than 100 barA, more preferably 200 barA or higher, and preferably less than 800 barA, more preferably less than 650 barA.

24. A turbomachine according to any one of claims 13 to 23, which is adapted to generate power higher than 50 MW, preferably 100 MW or more, preferably less than 2000 MW, and more preferably less than 1500 MW.

25. This is a supercritical carbon dioxide thermodynamic circuit, Oxidizing agent source, An expander having an inlet side and a discharge side, wherein the inlet side is fluidly coupled to the oxidizing agent source, A flue gas recirculation line adapted to recirculate flue gas from the discharge side of the expander to the combustor of the expander, A flue gas recirculation line is provided, which includes a cooler adapted to cool the flue gas from the discharge side of the expander and condense the moisture contained in the flue gas. A regenerative heat exchanger in which flue gas from the expander exchanges heat with the cooled flue gas from the cooler, Equipped with, The aforementioned expander is the expander described in any one of claims 13 to 24, in a supercritical carbon dioxide thermodynamic circuit.

Images