Rotor, turbo-machine power generator equipped with a rotor, and thermodynamic circuit using a turbo-machine.

Abstract

This specification discloses a rotor comprising a set of rotor discs. Each rotor disc comprises a corresponding annular row of rotor blades. The rotor further comprises a front shaft portion and a rear shaft portion. A first set of rotor discs is integrally formed with one of the front shaft portion and the rear shaft portion. The section of the shaft portion and the first set of rotor discs form a monolithic component. Furthermore, the front shaft portion and the rear shaft portion are connected to each other by a tie rod configuration.

Description

Technical Field

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

Background Art

[0002] Fossil fuels are the main source of chemical energy used for the generation of mechanical power. Fossil fuels are mixed with air, combusted to produce high-pressure and high-temperature combustion gases, and expanded in a turbine or 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 electrical 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 contributing to global warming and climate change.

[0004] To reduce the environmental impact of power generation from 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 to the environment. The cost of carbon dioxide capture facilities is high, both in terms of CAPEX and 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 large volumes 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 a mixture of oxidizers consisting mainly of oxygen (O2) and carbon dioxide (CO2). The mixture of fuel, oxygen, and carbon dioxide is burned in the combustor of an 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 thus 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-fuel 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 expander rotor design as the expander's rated power increases, and may impose limitations on the expander's maximum power rate.

[0010] For example, novel rotor and turbomachinery designs adapted to achieve higher power rates in oxygen fuel cycles would be welcomed in the field of art. [Overview of the project]

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

[0012] In embodiments disclosed herein, the rotor comprises a set of rotor discs, each rotor disc comprising a corresponding annular row of rotor blades. The rotor blades may be formed integrally with each rotor disc, or they may be manufactured as separate components to be attached to the rotor discs later. The rotor further comprises a front shaft portion and a rear shaft portion. The first set of rotor discs is formed integrally with a section of the front shaft portion. The section of the front shaft portion and the first set of rotor discs form a monolithic component. Furthermore, the front shaft portion and the rear shaft portion are connected to each other by a tie rod configuration. The first set of rotor discs may include one or more rotor discs.

[0013] An additional set of rotor discs can be formed integrally with the other half of the front and rear shaft portions. The other half of the front and rear shaft portions, along with the additional set of rotor discs, form a monolithic component. The additional set of rotor discs may include one or more rotor discs.

[0014] In some embodiments, the rotor may include at least one additional rotor disc, preferably a plurality of additional rotor discs, positioned between the front shaft portion and the rear shaft portion. The front shaft portion, the additional rotor discs, and the rear shaft portion are stacked on top of each other and connected to each other by a tie rod configuration.

[0015] In some embodiments, a first set of rotor discs is formed integrally with the front shaft portion, and a plurality of additional rotor discs are positioned between the front and rear shaft portions. The front shaft portion, the plurality of rotor discs, and the rear shaft portion are stacked on top of each other and connected by a tie rod configuration.

[0016] In another embodiment, this specification discloses power-generating turbomachinery, such as an expander, which includes a rotor outlined above and described in more detail below. In embodiments disclosed herein, the turbomachinery 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] Further features of the rotor and turbomachinery are described in the dependent claims. [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 of an expander in one embodiment. [Figure 3] This is a cross-sectional view of a portion of the rotor for the expander shown in Figure 2, in a further embodiment. [Modes for carrying out the invention]

[0019] The schematic diagram in Figure 1 shows a simplified supercritical carbon dioxide cycle (sCO2 cycle), such as the Aram cycle or a similar oxygen-fuel combustion cycle, in which the use of an expander including a rotor according to this disclosure may be particularly beneficial. In general terms, a supercritical carbon dioxide cycle as understood herein is a cycle in which carbon dioxide is in a supercritical state at least at the inlet of the expansion channel of the expander.

[0020] The power system 1 shown in Figure 1 comprises an expander 3 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 Figure 2. In some embodiments, the combustion chambers are housed within the high-pressure casing of the expander, as schematically shown in Figure 1. In some embodiments, each combustion chamber is housed in its respective seat formed in the high-pressure casing of the expander, as will be described in more detail below.

[0021] Reference numeral 7.1 in Figure 2 indicates a single combustion chamber of a can-type combustor or a 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 oxidizer stream provided by an oxidizer source. The oxidizer may be oxygen (O2) or a mixture of oxygen and carbon dioxide (CO2). The oxidizer stream can be generated by an air separation unit 9 having an oxidizer source. The air separation unit 9 may remove nitrogen or nitrogen and carbon dioxide from the ambient air to generate the necessary oxidizer stream supplied to the combustor 7 of the expander 3 through the oxidizer line 11. In some embodiments, for easier handling of the oxidizer stream, the oxidizer stream may contain about 20 vol% oxygen and 80 vol% carbon dioxide. The above CO2 and O2 ratios are examples. Carbon dioxide can be added to the oxygen through a 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 combustion chamber 7.1. The oxidant and the 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 in the first expansion stage, can be 100, 150, 200, 250, 300, or 350 barA.

[0024] The mixture of the oxidant and the fuel is combusted 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, that is, at the inlet of the expander rotor, can be included, for example, in the range of 800 °C to 1500 °C.

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

[0026] The circuit further includes a regenerative heat exchanger 17. 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 the low-temperature 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 the low-temperature heat exchanger 19 to a temperature that causes condensation of the steam contained in the exhausted flue gas. The condensed water is removed from the exhausted flue gas in the 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 on the inlet side 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 can be used. For example, the flue gas compressor 23 can be a multi-stage compressor or a compressor train. In some embodiments, the compressor can be an intercooled compressor. In some embodiments, the main compressor can 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 turbomachines arranged in series, the discharge line 25 may be connected, for example, between two consecutively arranged turbomachines and / or to the discharge side of the furthest downstream turbomachine.

[0029] Most of the 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 then 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 and / or 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 that can be 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 on the output shaft end 31 for mechanical drive or power generation. 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. A 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 a 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 from the combustor 7, i.e., the discharge side of the expander 3.

[0033] The high pressure drop across the expander 3, the high absolute pressure in the combustor 7 and the expander cooling duct, and the high torque applied to the expander shaft present significant challenges to the design of the expander 3, particularly for high rated powers of 100 MW or more, such as 100 MW to 2000 MW. The expander, and especially the rotor designs disclosed herein, can be used to achieve high power rates of the order of 50 MW or more, for example, 100 MW or more, for example, 150 MW or more, for example, 200 MW or more, or 300 MW or more. 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 can be included in the range of 200 MW to 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 Figure 1, Figure 2 shows a cross-sectional view of the expander 3 in one embodiment.

[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 and 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.

[0036] The low-pressure exhaust casing 41.2 can be positioned on the discharge side of the expander 3, i.e., the rear side, i.e., opposite to the combustor 7. The low-pressure exhaust casing 41.2 can be monolithic, i.e., it can 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 divided into two parts along a plane containing the rotation axis 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 forms an exhaust volute or exhaust plenum 41.3 through which the exhausted flue gas is discharged from the expander 3. In some embodiments, the high-pressure casing 41.1 forms seats for individual combustion chambers 7.1, accumulating the combustor 7 as shown in Figure 2.

[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 from the combustor 7, i.e., the rear side, may include an axial bearing or thrust bearing in combination with a radial bearing, or a bearing having axial-radial bearing capability. The bearing device 47 on the combustor side, i.e., the front 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 may be housed in bearing housings 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. When two or more inner casings are provided, they can be tightly coupled to one another. The two or more inner casings are arranged continuously along the axial direction of the expander and together form a single inner casing configuration.

[0041] 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, a plane containing the rotation axis AA. The arrangement of one or more inner casings 51 positioned inside the outer casing 41 is particularly beneficial when the combustion gases reach high pressures of about 200-300 barA 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.

[0042] The pressure drop before and after 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 is preferable to expand the combustion gas generated in the combustor 7. In the exemplary embodiment shown in Figure 2, the expander 3 includes eight stages. In other embodiments, a different number of expansion stages can be assumed, preferably four or more, more preferably five or more. In some embodiments, the number of expansion stages can be more than eight, for example, nine, ten, eleven, or more, and preferably less than fifteen. The expansion stages form axial expansion passages for the process gas to be expanded in the expander 3.

[0043] Each expansion stage includes an annular row of fixed vanes or fixed blades 53 fixedly arranged within the expander 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 the expansion flow path extending from front to rear from the combustor 7 to the discharge plenum 41.3.

[0044] In some embodiments, the first annular row 53.1 of the fixed blades may be located at the exhaust end of the combustor 7 and may form an array of nozzles that guide high-temperature, high-pressure gas from the combustion chamber 7.1 of the combustor 7 to the first row of rotor blades. The first annular row of rotor blades, indicated as 55.1, may be located immediately downstream of the first annular row 53.1 of the fixed blades adjacent to the combustor 7. The last annular row 53.8 of the fixed blades may be located upstream of the last annular row of rotor blades, indicated as 55.8, and 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.

[0045] The rotor blades 55 form part of the rotor 43 and are connected to the rotor 43 so as to rotate with the rotor shaft. In this embodiment, each annular row of rotor blades 55 (i.e., each row 55.i, i=1 to 8) is connected to its respective rotor disk. The rotor disks are denoted as 57.1, 57.2, 57.3, 57.4, 57.5, 57.6, 57.7, and 57.8. Reference numeral 57 indicates a general rotor disk.

[0046] The rotor blades 55 can be manufactured separately from each rotor disk 57 and attached to the rotor disk 57 by appropriate connecting means. In other embodiments, the rotor blades 55 can be manufactured monolithically with each rotor disk 57, 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, and one or more stages may include the rotor disks and separately manufactured rotor blades mechanically coupled to the rotor disks.

[0047] In the embodiment of Figure 2, the first set of rotor discs comprises rotor discs 57.1, 57.2, 57.3, and 57.4. The first set of rotor discs 57.1, 57.2, 57.3, and 57.4 are manufactured monolithically with the front shaft portion 65. More specifically, in the embodiment of Figure 2, the front shaft portion 65 comprises a first section 65A and a second section 65B. The rotor discs 57.1, 57.2, 57.3, and 57.4 of the first set of rotor discs are formed integrally with section 65B of the front shaft portion 65. For example, the rotor discs 57.1, 57.2, 57.3, and 57.4 and section 65B of the front shaft portion 65 can be formed from a single body manufactured by forging, machining, casting, or a combination thereof.

[0048] In other embodiments, the front shaft portion 65 can be manufactured as a monolithic body rather than as two sections 65A and 65B. In such cases, the entire front shaft portion and the rotor discs 57.1, 57.2, 57.3, and 57.4 can be manufactured as a monolithic single piece.

[0049] The annular rows of rotor blades 55.5, 55.6, and 55.7 are manufactured separately from the front shaft section 65 and mounted on their respective additional rotor discs 57.5, 57.6, and 57.7, which are drivably coupled to the front shaft section 65 as described below.

[0050] In some embodiments, an additional set of rotor discs forms a single monolithic block with the rear shaft portion 67 of the rotor 43. The rear shaft portion 67 can be formed as a single piece, as shown. In other embodiments not shown, the rear shaft portion 67 may comprise two or more sections, just like the front shaft portion 65 and its associated sections 65A, 65B.

[0051] In the embodiment shown in Figure 2, the additional set of rotor disks includes a single rotor disk 57.8. In other embodiments not shown, the additional set of rotor disks may include two or more rotor disks.

[0052] In yet another embodiment not shown, the rotor 43 may include only a first set of rotor discs monolithically formed with the front shaft portion 65 or a section thereof, and an additional set of rotor discs monolithically formed with the rear shaft portion 67, and may not include intermediate discs stacked between the first set of rotor discs and the additional set of rotor discs. Conversely, as will be discussed later with reference to Figure 3, the rotor may include a section of the front shaft portion and a rotor disc monolithically manufactured, and an additional single rotor disc positioned between the front shaft portion and the rear shaft portion, while the rear shaft portion does not have a rotor disc monolithically formed with the front shaft portion.

[0053] In the embodiment, as shown in Figure 2, the combustor 7 extends around a front shaft portion 65. If the combustor is a can-type combustor having a plurality of combustion chambers 7.1 arranged around the rotation axis of the rotor 43, the combustion chambers can be housed around the front shaft portion 65 within a high-pressure casing 41.1, as shown in Figure 2. As shown in Figure 2, each combustion chamber 7.1 can be housed within the high-pressure casing 41.1, specifically within a seat formed monolithically on its front side.

[0054] In some embodiments, the discharge volute 41.3 formed by the low-pressure discharge casing 41.2 extends around the rear shaft portion 67.

[0055] The rear shaft portion 67, the front shaft portion 65 (specifically, its section 65B), and the intermediate rotor discs 57.5, 57.6, and 57.7 are stacked on top of each other and connected by a tie rod configuration. In the exemplary embodiment shown in Figure 2, the tie rod configuration includes a plurality of tie rods 70 arranged around the rotation axis AA of the rotor 43.

[0056] In other embodiments not shown, the tie rod configuration is coaxial with the rotor, i.e., includes a single tie rod coaxial with the axis of rotation AA.

[0057] In yet another embodiment, the tie rod configuration may include both a central tie rod coaxial with the rotation axis AA and a set of tie rods 70 positioned radially away from the rotation axis AA, as shown in Figure 2.

[0058] In some embodiments, each intermediate rotor disc 57.5, 57.6, 57.7 includes a front tooth on each side for torsional engagement with the front teeth of the adjacent rotor disc and / or the front teeth of the front shaft portion 65 and the rear shaft portion 67. The front teeth form hearth joints between rotor discs 57.5 to 57.7, between the first intermediate rotor disc 57.5 and the front shaft portion 65, and between the last intermediate rotor disc 57.7 and the rear shaft portion 67.

[0059] Providing front teeth may be beneficial in increasing the torque that can be transmitted from the front shaft portion 65 to the rotor discs 57.5, 57.6, and 57.7, from the rotor discs 57.7 to the rear shaft portion 67, and between each of the rotor discs 57.5, 57.6, and 57.7. In some embodiments, front teeth may be provided only in some sections of the rotor where the transmitted torque is higher, i.e., the most downstream section of the 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 of the expander 3 (opposite the combustor 7 as in the illustrated embodiment) or on the front side (side of the combustor 7). Output shafts on both sides (rear and front) can also be foreseen.

[0060] In some embodiments, each seal runner 68 is positioned between each pair of consecutive (i.e., adjacent) rotor disks 57 and seals an annular space provided radially inward of each fixed blade 53.

[0061] In some embodiments, the expander 3 includes a balance drum drivably coupled to the rotor 43. In the embodiment shown in Figure 2, 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, more specifically on the front shaft portion 65.

[0062] In some embodiments, the balance drum 75 is formed integrally with the front shaft portion 65.

[0063] In this embodiment, as shown in Figure 2, the two sections 65A and 65B of the front shaft portion 65 can be connected to each other by a plurality of tie rods 77 arranged in a circle 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. In this embodiment, the flanges 75.1 and 75.2 cumulatively form a balance drum 75.

[0064] 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.

[0065] The rotor 43 is cooled by supplying pressurized cooling fluid to cooling ducts formed in the rotor 43. Specifically, in some embodiments, compressed and cooled carbon dioxide may be sent to a cooling chamber 81 inside the rotor 43. The cooling chamber 81 can be formed inside the intermediate rotor discs 57.5, 57.6, and 57.7 and can be closed at the rear and front ends by the rear shaft portion 57 and the front shaft portion 65, respectively.

[0066] For example, pressurized carbon dioxide supplied by the flue gas compressor 23 via a cooling line 27 (Figure 1) can be supplied to the cooling chamber 81 via a duct 83, flowing through radial holes (not shown) in the rotor 43, buffering and cooling the space 58 between adjacent disks 57. The duct 83 is fluidically coupled to a cooling plenum 85 adapted to receive the cooled carbon dioxide. The cooling chamber 81 provides cooled carbon dioxide to the last five stages of the expander 3. The first three stages of the expander 3 can be cooled through one or more ducts 87, which extend parallel to the rotor axis AA and duct 83 and are fluidly coupled to the cooling plenum 85. Specifically, radial cooling ducts can fluidly couple the cooling chamber to the annular space between rotor disks 57.4-57.8, which are sealed radially outward by their respective seal runners 68. Furthermore, each radial cooling duct 87 can be fluidly coupled to the annular spaces provided between the forward shaft portion 65 and the monolithically formed rotor disc, i.e., rotor discs 57.1, 57.2, 57.3, and 57.4. These annular spaces can also be sealed radially outward by their respective seal runners 68.

[0067] In other embodiments not shown, the cooling chamber may be located within the forward shaft section 65B, from which a radial duct can direct the cooling duct toward one or more annular rings of the rotor blades formed integrally with the forward shaft section 65B.

[0068] In some embodiments, for example, if the first set of monolithically manufactured rotor disks in the front shaft section 65B includes only one or two disks, cooling can be achieved by fluidly coupling the disk to a central cooling chamber 81 located inside a single rotor disk stacked between the front shaft section 65A and the rear shaft section 67.

[0069] The cooling fluid supplied beneath each seal runner 68 in the annular space between adjacent rotor discs purges each annular space, preventing process fluid from flowing through it. Therefore, the pressure of the cooling fluid must be sufficient to balance the pressure of the process fluid expanding along the expansion passage formed by the fixed blades 53 and rotor blades 55. The pressure of the process fluid decreases along the passage from the first expansion stage to the last expansion stage. Therefore, the cooling fluid pressure required in the most upstream expansion stage is very high, and can be, for example, between 200 barA and 600 barA. The most upstream rotor disc is monolithically formed with the forward shaft portion 65 and, more specifically, its section 65B, providing sufficient mechanical strength to withstand the high pressures that tend to separate the rotor discs from each other.

[0070] In the final stages of the expander 3, for example, the last four stages, the pressure of the process fluid is lower, and therefore the pressure of the cooling fluid in the annular space between the rotor discs is also lower. The axial force that attempts to separate the rotor discs from each other due to the cooling fluid pressure is small enough that the separate, mutually stacked rotor discs can be assembled by the tie rods 70. To provide the cooling fluid in the annular space between the continuously arranged rotor discs at a gradually decreasing pressure, the duct through which the cooling fluid is delivered to the annular space may have a variable cross-section to provide increasing head loss from the upstream to the downstream expander stages, i.e., from front to rear.

[0071] By dividing the rotor disc into a first set of monolithic rotor discs (57.1, 57.2, 57.3, and 57.4) formed as a single unit with the front shaft portion 65 (i.e., its section 65B), and additional rotor discs (57.5, 57.6, and 57.7) stacked using tie rods 70, the required mechanical strength is provided without the need to manufacture the entire rotor as a monolithic unit, for example, by forging.

[0072] Therefore, combining monolithic rotor discs with stacked rotor discs allows for the manufacture of larger rotors, resulting in expanders with higher power rates. Achieving the same rotor dimensions by forging the rotor as a single piece is difficult, if not impossible.

[0073] In Figure 2, the additional rotor disc set integrated with the rear shaft portion 67 includes a single rotor disc 57.8, but in other embodiments not shown, the additional rotor disc set 57 may include more rotor discs, for example, two, three, or four, formed integrally with the rear shaft portion 67 as a monolithic body.

[0074] Further embodiments of the rotor that can be used in the expander 3 are shown in the cross-sectional view of Figure 3. The same reference numerals indicate parts that are the same as or equivalent to the parts shown in Figure 2 and described above, and are not described again.

[0075] The rotor 43 in Figure 3 differs from the rotor shown in Figure 2 in that the rotor disc is divided into a first set of rotor discs 57.1, 57.2, 57.3, and 57.4, which are integrally formed as a monolithic block together with section 65B of the front shaft portion 65, and separate individual rotor discs 57.5, 57.6, 57.7, and 57.8, which are positioned between the front shaft portion 65 and the rear shaft portion 67 and stacked together with them, and are formed as all separate components. The front shaft portion 65 (and more specifically, its section 65B), the rotor discs 57.5, 57.6, 57.7, and 57.8, and the rear shaft portion 67 are stacked together and are connected to each other by tie rods 70, as shown in Figure 3, or by a central tie rod coaxial with the rotation axis AA, or by a different configuration of tie rods including it, as described above with reference to Figure 2, for example. In this embodiment, there are no further rotor discs integrally formed with the rear shaft portion 67. The embodiment shown in Figure 3 has the advantage of having a smaller rear shaft portion compared to the embodiment shown in Figure 2, making it easier to manufacture by forging or other manufacturing techniques.

[0076] 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.

[0077] For example, in the particularly advantageous embodiment disclosed above, the combustor is housed inside the expander, but in other embodiments, the combustor can be located outside the expander. By housing the combustor inside the outer casing 41 of the expander 3, a more compact configuration can be obtained.

[0078] In other embodiments, the expander can be used in closed-loop thermodynamic cycles such as the supercritical carbon dioxide cycle, in which case heat is introduced into the thermodynamic cycle via a heat exchanger rather than using a combustor.

Claims

1. A rotor for a power generation turbomachinery, wherein the rotor is A plurality of rotor disks, each rotor disk comprising an annular row of rotor blades in the expansion passage of the power-generating turbomachine, The front shaft section, The rear shaft section, The system comprises at least one cooling duct adapted to supply cooling fluid to the rotor disk, A first set of rotor discs is formed integrally with the section of the front shaft portion, and the first set of rotor discs and the section of the front shaft portion form a monolithic component. A rotor in which the front shaft portion and the rear shaft portion are connected to each other by a tie rod configuration.

2. The rotor according to claim 1, wherein an additional set of rotor discs is formed integrally with the rear shaft portion, and the rear shaft portion and the additional set of rotor discs form a monolithic component.

3. The rotor according to claim 1 or 2, comprising at least one additional rotor disc between the front shaft portion and the rear shaft portion, wherein the front shaft portion, the at least one additional rotor disc, and the rear shaft portion are stacked on top of each other and connected to each other by the tie rod configuration.

4. The rotor according to claim 1, 2, or 3, wherein a plurality of additional rotor discs are positioned between the front shaft portion and the rear shaft portion, and the front shaft portion, the plurality of rotor discs, and the rear shaft portion are stacked on top of each other and connected to each other by the tie rod configuration.

5. The rotor according to one or more of claims 1 to 4, further comprising a cooling chamber adapted to receive cooling fluid from the cooling duct within the rotor.

6. The rotor according to claim 5, wherein the cooling chamber is disposed between the front shaft portion and the rear shaft portion.

7. The rotor according to claim 5, as dependent on claim 3, wherein the cooling chamber is formed between the front shaft portion, the at least one additional rotor disk, and the rear shaft portion.

8. The rotor according to one or more of claims 1 to 7, wherein a radial cooling duct is fluidly coupled to an annular space between a pair of continuously arranged rotor discs.

9. The rotor according to one or more of claims 1 to 8, wherein the tie rod configuration comprises a plurality of tie rods arranged radially away from the rotation axis of the rotor, a central tie rod coaxial with the rotation axis of the rotor, or a combination of a central tie rod and a plurality of tie rods arranged around the rotation axis of the rotor.

10. A rotor according to one or more of claims 1 to 9, further comprising a balance drum.

11. The rotor according to claim 10, wherein the balance drum is formed on one of the front shaft portion and the rear shaft portion, preferably on the front shaft portion.

12. The rotor according to claim 10 or 11, 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, the tie rods being peripherally arranged around the rotation axis of the rotor at a radial distance from the rotation axis.

13. The rotor according to one or more of claims 1 to 12, wherein at least one of the rotor disks includes front teeth adapted to rotately engage the rotor disk with at least one of the adjacent rotor disks, the front shaft portion, and the rear shaft portion.

14. The rotor according to one or more of claims 1 to 13, wherein at least one cooling duct extends into the front shaft portion and is fluidly coupled to an annular space between rotor discs formed integrally with the front shaft portion.

15. A rotor according to any one of claims 1 to 14, comprising at least four, preferably at least six, and more preferably at least eight expansion stages.

16. It is a power generation turbomachine, Outer casing and A turbomachine comprising a rotor according to any one of claims 1 to 15, which is housed to rotate within the casing.

17. The turbomachinery according to claim 16, wherein the turbomachinery is an expander.

18. The turbomachinery according to claim 16 or 17, 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.

19. The turbomachinery according to claim 18, wherein the high-pressure casing comprises a monolithic barrel body.

20. The turbomachinery according to claim 18 or 19, wherein the low-pressure exhaust casing is configured as a monolithic body.

21. The turbomachine according to any one of claims 16 to 20, further comprising at least one combustor housed within the outer casing.

22. The turbomachinery according to claim 18, 19, or 20, further comprising at least one combustor housed in a seat formed within the high-pressure casing.

23. The turbomachinery according to claim 21 or 22, wherein the low-pressure exhaust casing is located on the low-pressure side of the expander, opposite to the combustor, and the low-pressure exhaust casing forms a discharge volute.

24. The turbomachinery according to any one of claims 16 to 23, further comprising at least one inner casing, preferably a plurality of inner casings, which are fixedly housed within the outer casing and surround 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 includes an annular row of fixed blades.

25. The turbomachinery according to any one of claims 16 to 24, wherein the rotor is adapted to receive a process gas at a temperature T in the range of 800°C to 1500°C.

26. The turbomachinery according to any one of claims 16 to 25, wherein the rotor is adapted to receive process gas at a pressure greater than 50 barA, preferably 100 barA or more, more preferably 200 barA or more, and preferably less than 800 barA, and more preferably less than 650 barA.

27. A turbomachinery according to any one of claims 16 to 26, which is adapted to generate an output of more than 50 MW, preferably 100 MW or more, preferably less than 2000 MW, and more preferably less than 1500 MW.

28. 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, In the aforementioned flue gas recirculation line, a cooler is provided which is adapted to cool the flue gas from the discharge side of the expander and condense the moisture contained in the flue gas, The system includes a regenerative heat exchanger through which flue gas from the expander flows in heat exchange with the cooled flue gas from the cooler, A supercritical carbon dioxide thermodynamic circuit, wherein the expander is the expander described in any one of claims 16 to 27.

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