Expander for oxygen fuel combustion cycles, etc.

Abstract

The supercritical expander includes an outer casing and a rotor housed within the outer casing so as to rotate around a rotation axis. At least one combustor is housed within or associated with the casing. The outer casing includes a high-pressure casing and a low-pressure exhaust casing coupled to each other by flange connections along a plane perpendicular to the rotation axis. The low-pressure exhaust casing includes an exhaust plenum adapted to collect combustion gases expanded through a gas expansion passage. The low-pressure exhaust casing includes at least one exhaust aperture, wherein the expander comprises an outer casing and a rotor housed within the outer casing so as to rotate around a rotation axis.

Description

Technical Field

[0001] The present disclosure relates to a gas expander particularly adapted for use in an oxygen fuel combustion cycle operating with a high-pressure process gas, such as a CO2 cycle (sCO2 cycle), such as the Allam cycle, also known as the NET Power Cycle.

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 and burned to produce combustion gases at high pressure and high temperature, and these combustion gases expand in 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 electrical power.

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

[0004] To reduce the environmental impact of power generation by burning 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, reducing 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 or oxygen fuel combustion cycle, has been developed, in which a fuel such as natural gas or another fossil fuel is blended under high pressure with a mixture of an oxidizer consisting mainly of oxygen (O2) and carbon dioxide (CO2). The blend of fuel, oxidizer, and carbon dioxide is burned in the combustor of the expander to produce a 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, where it is further cooled to form condensate, 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 cycle described above is particularly interesting in terms of efficiency, reduction of harmful emissions, and CO2 sequestration. However, these operate under supercritical CO2 conditions at the expander inlet and are characterized by high pressure values ​​inside the expander casing. These operating conditions impose difficult constraints on casing design.

[0010] Novel expander designs adapted to achieve higher power rates in oxygen fuel combustion cycles would be welcomed in the field. [Overview of the Initiative]

[0011] To address the aforementioned needs, a high-pressure expander is disclosed herein, comprising an outer casing, a rotor housed within the outer casing so as to rotate around a rotation axis, and at least one combustor. The outer casing includes a high-pressure casing and a low-pressure exhaust casing coupled to each other by flange connections along a plane perpendicular to the rotation axis of the rotor. The low-pressure exhaust casing includes an exhaust plenum adapted to collect combustion gases expanded through a gas expansion passage, and at least one exhaust aperture.

[0012] Specifically, the expander may be a supercritical expander. As understood herein, a supercritical expander is an expander adapted to receive a working fluid in a supercritical state in the first expansion stage. Embodiments described herein are particularly adapted as a CO2 supercritical expander, i.e., an expander adapted to expand carbon dioxide starting from supercritical conditions.

[0013] The combustor can be mounted on or around the casing of the expander. In some embodiments, the combustor is at least partially housed within the casing.

[0014] Further features and embodiments of the inflator are described below with reference to the accompanying drawings and outlined in the accompanying claims.

[0015] In a further embodiment, this specification discloses an oxygen fuel combustion system comprising an expander as outlined above and a compression system adapted to provide a flow of compressed process gas to the expander. [Brief explanation of the drawing]

[0016] 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] The diagrams show unequal angle projections of low-pressure exhaust casings having multiple discharge apertures in several embodiments. [Figure 4] The diagrams show unequal angle projections of low-pressure exhaust casings having multiple discharge apertures in several embodiments. [Figure 5] The diagrams show unequal angle projections of low-pressure exhaust casings having multiple discharge apertures in several embodiments. [Figure 6] The diagrams show unequal angle projections of low-pressure exhaust casings having multiple discharge apertures in several embodiments. [Figure 7] The diagram shows a cross-sectional view of a low-pressure exhaust casing discharge aperture having means adapted to prevent thermal damage and reduce the thermal load on the low-pressure exhaust casing in several embodiments. [Figure 8] The diagram shows a cross-sectional view of a low-pressure exhaust casing discharge aperture having means adapted to prevent thermal damage and reduce the thermal load on the low-pressure exhaust casing in several embodiments. [Figure 9] The diagram shows a cross-sectional view of a low-pressure exhaust casing discharge aperture having means adapted to prevent thermal damage and reduce the thermal load on the low-pressure exhaust casing in several embodiments. [Figure 10] Details of the coupling between the high-pressure casing and the low-pressure exhaust casing in several embodiments are shown. [Figure 11] Details of the coupling between the high-pressure casing and the low-pressure exhaust casing in several embodiments are shown. [Figure 12] Details of the coupling between the high-pressure casing and the low-pressure exhaust casing in several embodiments are shown. [Figure 13] Details of the coupling between the high-pressure casing and the low-pressure exhaust casing in several embodiments are shown. [Figure 14] Details of the coupling between the high-pressure casing and the low-pressure exhaust casing in several embodiments are shown. [Figure 15] Shows the details of the connection between the high-pressure casing and the low-pressure exhaust casing in some embodiments. [Figure 16] Shows the details of the connection between the high-pressure casing and the low-pressure exhaust casing in some embodiments. [Figure 17] Shows the details of the connection between the high-pressure casing and the low-pressure exhaust casing in some embodiments. [Figure 18] Shows the details of the connection between the high-pressure casing and the low-pressure exhaust casing in some embodiments. [Figure 19] Shows the details of the connection between the high-pressure casing and the low-pressure exhaust casing in some embodiments. [Figure 20] Shows the details of the connection between the high-pressure casing and the low-pressure exhaust casing in some embodiments. [Figure 21] Shows the details of the connection between the high-pressure casing and the low-pressure exhaust casing in some embodiments. [Figure 22] Shows a schematic cross-sectional view of an expander designed for forward insertion of the rotor. [Figure 23] Is a cross-sectional view of two adjacent combustion chambers. [Figure 24] Is a schematic view of an alternative arrangement of the exhaust apertures provided in the low-pressure exhaust casing. [Figure 25] Is a schematic view of an alternative arrangement of the exhaust apertures provided in the low-pressure exhaust casing. [Figure 26] Is a schematic view of an alternative arrangement of the exhaust apertures provided in the low-pressure exhaust casing. [Figure 27] Is a schematic view of an alternative arrangement of the exhaust apertures provided in the low-pressure exhaust casing.

Mode for Carrying Out the Invention

[0017] Figure 1 shows a schematic diagram of a simplified oxygen fuel cycle (abbreviated as the sCO2 cycle), such as the Allam cycle or the NET Power oxygen fuel cycle, which operates using supercritical carbon dioxide at the expander inlet.

[0018] The power system 1 shown in Figure 1 includes an expander 3, which includes 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 which includes a plurality of combustor chambers arranged around the rotation axis of the expander 3, as shown in more detail in Figure 2. The combustor chambers are housed within the outer casing of the expander, as will be described in more detail below.

[0019] Reference numeral 7.1 in Figure 2 indicates the combustion chamber of an annular combustor, or each combustion chamber of a can-type or can-annular combustor. In some embodiments, each combustion chamber 7.1 is housed in its respective seat 41.4 formed within a high-pressure casing 41.1. The combustion chambers 7.1 are arranged circumferentially around the rotation axis of the expander 3.

[0020] The combustor 7 is supplied with an oxidant stream provided by an oxidant source. The oxidant may be oxygen (O2) or a blend of oxygen and carbon dioxide (CO2). 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 the ambient air to generate the necessary oxidant stream that is supplied to the combustor 7 of the expander 3 through the oxidant line 11.

[0021] 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 oxidizer and fuel are supplied to the combustor 7 at high pressure, for example, 50 barA or more, preferably 100 barA or more, more preferably 150 barA or more, and more preferably 200 barA or more, at the inlet side of the expander 3. In some embodiments, the upper pressure of the cycle may be 250 barA or more, or higher, for example, 300 barA or more. The blend of oxidizer and fuel is burned in the combustor 7. The pressurized, high-temperature combustion gases resulting from the combustion expand in the expansion section 5 of the expander 3.

[0022] In some embodiments, the temperature at the inlet of the gas expansion passage, i.e., at the rotor inlet, may be 800°C or higher, preferably 1500°C or lower.

[0023] The exhausted flue gas is discharged into the discharge line 15 on the discharge side of the expander 3. The flue gas in the discharge line 15 is, for example, about 600°C and can have a pressure in the range of 10 barA to 100 barA, for example, 20 barA to 60 barA.

[0024] The power output of the expander 3 is higher than 50 MW and can be, for example, 100 MW or more, for example, 150 MW or more, or for example, 200 MW or more. In some embodiments, the rated power is 300 MW or more. In some embodiments, the rated power is 2000 MW or less, for example, 1500 MW or less, or 1000 MW or less. For example, the rated power can be set between 200 MW and 650 MW. The midpoints of the upper and lower limits of each of the above ranges are also expressly disclosed herein.

[0025] The circuit further includes a regenerative heat exchanger 17, where the hot flue gas flowing through the hot side 17.1 of the regenerative heat exchanger 17 is cooled by heat exchange with the flow of cooled 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 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.

[0026] 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 may be used. For example, the flue gas compressor 23 may be a multi-stage compressor or compressor train and may include one or more intercoolers.

[0027] The compressed flue gas supplied by the flue gas compressor 23 is partially removed from the cycle through the discharge line 25. 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 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.

[0028] A sidestream of cooled flue gas is sent through a cooling line 27 that bypasses the regenerative heat exchanger 17 to components of the expander 3 that require cooling. Further sidestreams of cooled and dehydrated flue gas are sent through line 28 to the air separator 9 and / or oxidizer line 11, where carbon dioxide can be added to the oxygen sent to the combustor 7.

[0029] 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 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 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 one on the rear side.

[0030] 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.

[0031] Figure 2 shows a cross-sectional view of an expander 3 in one embodiment. The expander 3 may include an outer casing 41 that houses a combustor 7. In this embodiment, the outer casing 41 includes a high-pressure casing 41.1 and a low-pressure exhaust casing 41.2. The high-pressure casing 41.1 may be in the form of a barrel including a monolithic body manufactured, for example, by forging, casting, or a combination thereof. The monolithic body extends around the longitudinal axis of the expander, i.e., around the axis of rotation.

[0032] In some embodiments, the monolithic body is manufactured starting from a single block, but as understood herein, the monolithic body may also include a body assembled from several parts that are manufactured separately from each other and then assembled together by welding to obtain the final monolithic body. The parts are irreversibly joined to each other. To achieve higher mechanical strength, each part of the monolithic body preferably extends around the rotation axis of the expander, i.e., each part of the monolithic body is joined to each other along a surface that extends laterally with respect to the rotation axis. Each part has an annular structure, i.e., a continuous structure surrounding the rotation axis. As understood herein, the continuous structure surrounding the rotation axis of the expander is a structure in which the closed line surrounding the rotation axis of the expander does not cross any welds or mechanical interfaces between the parts that form the monolithic body.

[0033] The continuous structure surrounding the rotating shaft has higher mechanical resistance to radial and tangential loads generated by internal pressure.

[0034] A single component formed by a monolithic body (either manufactured from a single component or by individual components welded together to form the final barrel without reversible mechanical connections) provides adequate resistance to the high pressure of the process fluid inside the expander 3, particularly its foremost section.

[0035] 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 may also be monolithic, i.e., it may consist of a single component as described above, having a continuous structure that unfolds around the axis of rotation.

[0036] In other embodiments, the low-pressure exhaust casing 41.2 can be manufactured from two or more parts connected to one another. For example, the low-pressure exhaust casing 41.2 can be manufactured as a body consisting of two parts separated along a plane containing the rotor's axis of rotation. The two parts may be welded to each other, i.e., irreversibly connected to one another. In other embodiments, the parts from which the low-pressure exhaust casing 41.2 is made can be joined to each other by tie rods, screw bolts, or other reversible coupling means. Reversible coupling means are understood to be coupling devices that allow two or more parts forming the casing to be separated again without irreversible damage.

[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. Thus, the outer casing 41 is a so-called "vertically split" casing.

[0038] In some embodiments, the low-pressure exhaust casing 41.2 forms an 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 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.

[0040] The output end 31 of the rotor 43 can be drivably coupled to a driven machine (generator 33) via a flange 49. Bearing devices 45 and 47 can be housed in bearing housings not shown in detail.

[0041] The rotor 43 is surrounded by an inner casing 51 which can be formed by a plurality of sections arranged sequentially from front to rear. In Figure 2, the inner casing 1 includes two casing sections arranged continuously from front to rear, i.e., parallel to the axis of rotation. The inner casing 51 can be divided horizontally, i.e., it can include two parts joined together along the plane containing the axis of rotation of the rotor 43. If the inner casing includes two casing sections arranged continuously in the axial direction, each section can be divided into two parts along the plane containing the axis of rotation of the rotor 43.

[0042] The inner casing 51 is fully or partially housed within the high-pressure casing 41.1. In some embodiments, as shown in Figure 2, the inner casing 51 protrudes into the low-pressure exhaust casing 41.2.

[0043] In some embodiments, the inner casing 51 is equipped with a cooling duct, one of which is schematically shown in Figure 2 as 51.1. The cooling duct provides a fluid coupling between one or each of the annular fluid chambers 42.1, 42.2 and the interior of the inner casing 51. The cooling duct, such as compressed, recirculated flue gas consisting mainly of carbon dioxide, flows from the annular fluid chamber into the interior of the inner casing 51 to cool or purge the annular cavity inside the inner casing 51. An external cooling duct may be provided in combination with, or as an alternative to, the cooling duct extending through the inner casing.

[0044] One or more annular fluid chambers 42 are formed between the inner casing 51 and the outer casing 41. Specifically, in the exemplary embodiment shown in Figure 2, the annular chamber 42 includes two continuously arranged annular fluid chambers 42.1 and 42.2 separated by a partition wall 44. The fluid pressures inside the two annular fluid chambers 42.1 and 42.2 may differ. For example, the front annular fluid chamber 42.1 may have a higher pressure than the rear annular fluid chamber 42.2. During use, under steady-state conditions, the rear fluid chamber 42.2 and the front fluid chamber 42.1 can be supplied with chilling or cooling fluid, such as cooled and dehydrated flue gas from a cooling line 27.

[0045] The partition wall 44 or other connecting member, adapted to connect the inner casing 51 to the outer casing 41, is configured to allow for differences in thermal expansion between the inner casing 51 and the outer casing 41 in order to take into account different temperature conditions of the casing under steady-state operating conditions and during the transient conditions of starting and stopping.

[0046] The expander may be adapted to expand the combustion gas through the gas expansion passage with a pressure drop of at least 150 bar, preferably at least 250 bar, and more preferably 250 to 400 bar. A number of expansion stages is preferable for expanding the combustion gas generated in the combustor 7. In the exemplary embodiment shown in Figure 2, the expander 3 includes eight stages, each configured as an axial expansion stage. 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.

[0047] Each expansion stage includes an annular row of fixed blades or fixed vanes 53 fixedly positioned 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 53 along an expansion flow path extending from front to rear from the combustor 7 through the expansion section 5 to the discharge plenum 41.3.

[0048] The rotor blades 55 form part of the rotor 43 and are connected to the rotor 43 so as to rotate together with the rotor shaft. In some embodiments, each annular row of rotor blades 55 is connected to a respective rotor disk, which is not shown in detail. The structure of the rotor and rotor disk is not important and is not shown in detail.

[0049] In some embodiments, the rotor 43 further includes a front shaft portion 65 and a rear shaft portion 67. In some embodiments, 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.

[0050] The balance drum 69 can be constrained to the rotor 43 so as to rotate with the rotor 43. In the embodiment shown in Figure 2, the balance drum 69 includes a first balance drum portion 69A and a second balance drum portion 69B connected to each other by a tie rod 70.

[0051] In the embodiment shown in Figure 2, the expander 3 is configured such that the rotor 43 is installed into the outer casing 41 from the rear, i.e., from the low-pressure side of the expander. In some embodiments, a bundle including the inner casing 51 and the rotor 43 is assembled and introduced axially from the rear into the high-pressure casing 41.1. Finally, the low-pressure exhaust casing 41.2 is installed into the high-pressure casing 41.1.

[0052] In some embodiments, the low-pressure exhaust casing 41.2 may include multiple exhaust apertures instead of a single one. Providing multiple exhaust apertures results in a structure for the low-pressure exhaust casing 41.2 that is better suited to withstanding the associated high pressure and temperature values. The total cross-sectional area of ​​the multiple exhaust apertures may be the same as that of a single aperture, but the overall structure is mechanically more robust.

[0053] Figures 3, 4, 5, and 6 show unequal projection views of the low-pressure exhaust casing 41.2 in various embodiments, each including multiple exhaust apertures.

[0054] Figure 3 shows an unequal angle projection from the rear of a low-pressure exhaust casing 41.2 in an embodiment that includes two exhaust apertures 46.1 and 46.2 oriented radially with respect to the axis of the expander 3, i.e., the axis of rotation of the rotor 43. In the embodiment of Figure 3, the two exhaust apertures 46.1 and 46.2 are arranged symmetrically around the axis of rotation with respect to the plane containing the axis of rotation.

[0055] Figure 4 shows an unequal angle projection from the rear of a low-pressure exhaust casing 41.2 in an embodiment that includes two exhaust apertures 46.3 and 46.4 oriented tangentially with respect to the axis of the expander 3, i.e., the axis of rotation of the rotor 43. In the embodiment of Figure 4, the two exhaust apertures 46.3 and 46.4 are symmetrical with respect to the axis of rotation.

[0056] Figure 5 shows an unequal angle projection from the rear of the low-pressure exhaust casing 41.2 in an embodiment that includes four exhaust apertures 46.5, 46.6, 46.7, and 46.8 oriented radially with respect to the axis of the expander 3, i.e., the axis of rotation of the rotor 43. In the embodiment of Figure 5, the four exhaust apertures 46.1 and 46.2 are arranged symmetrically around the axis of rotation with respect to the plane containing the axis of rotation.

[0057] Figure 6 shows an unequal angle projection from the rear of a low-pressure exhaust casing 41.2 in an embodiment that includes four exhaust apertures 46.9, 46.10, 46.11, and 46.12 oriented tangentially with respect to the axis of the expander 3, i.e., the axis of rotation of the rotor 43. In the embodiment of Figure 6, the two exhaust apertures 46.9, 46.10 and the two exhaust apertures 46.11, 46.12 are symmetrical with respect to the plane containing the axis of rotation.

[0058] In other embodiments, the low-pressure exhaust casing 41.2 may include a different number or arrangement of exhaust apertures. For example, in some embodiments, the low-pressure exhaust casing 41.2 may include three exhaust apertures.

[0059] For example, in some embodiments, the exhaust apertures can be arranged at a constant pitch along the tangential direction. Figure 24 shows such an arrangement having four exhaust apertures 46 at a constant pitch of 90° to each other. Figure 26 shows a similar arrangement having only three exhaust apertures 46 positioned at 120° to each other in the tangential direction.

[0060] In Figure 27, the three exhaust apertures 46 are spaced at a constant 120° interval from each other, but they are oriented radially rather than tangentially, as in Figure 26.

[0061] In Figure 25, the two exhaust apertures 46 (located at the bottom of the low-pressure exhaust casing in this embodiment) are arranged parallel to each other, while the two exhaust apertures 46 (located at the top of the low-pressure exhaust casing) are oriented at an angle to the horizontal, but are not parallel to each other and are not coaxial with the opposing exhaust apertures at the bottom of the low-pressure exhaust casing. In other embodiments not shown, the upper apertures may be coaxial.

[0062] In some embodiments, the exhaust aperture may have the same cross-sectional area. In other embodiments, the exhaust aperture may have different cross-sectional areas.

[0063] In some embodiments, the low-pressure exhaust casing 41.2 can be made of a metal alloy adapted to withstand the high temperatures of the exhaust flue gas after expansion. In such cases, the low-pressure exhaust casing 41.2 may not include any heat shielding at all, as schematically shown in Figure 7. In some embodiments, the low-pressure exhaust casing 41.2 in Figure 7 is made of a cast nickel-based alloy adapted to withstand temperatures in the range of 600°C in the continuous operation mode of the expander 3. In other embodiments, the low-pressure exhaust casing can be made of austenitic steel or an Fe-based alloy, or any other metal alloy adapted to withstand the operating conditions in terms of chemical and thermal resistance.

[0064] In other embodiments, the exhaust aperture of the low-pressure exhaust casing 41.2 may include an internal thermal protection section adapted to reduce heat exchange between the exhaust flue gas and the inner surface of the low-pressure exhaust casing, specifically the inner surface of the duct forming the exhaust aperture. Figures 8 and 9 show cross-sectional views of a single exhaust aperture of the low-pressure exhaust casing 41.2 in two embodiments.

[0065] In Figure 8, the heat shield or heat cladding 48 is located inside the typical exhaust aperture 46. The heat shield 48 can be made of a metal alloy that can withstand high temperatures over a long period of time, thus enabling continuous operation of the expander 3. In some embodiments, the heat shield 48 can be made of a nickel-based alloy, while the low-pressure exhaust casing 41.2 can be made of ferritic-martensitic or austenitic steel with appropriate protective weld overlays.

[0066] In some embodiments, an additional insulating material 48.2 can be provided between the heat shield 48 and the inner surface of the low-pressure exhaust casing 41.2.

[0067] In Figure 9, a heat shield 48 is provided inside the exhaust aperture 46, and a cooling chamber or jacket 48.1 is formed between the heat shield 48 and the low-pressure exhaust casing 41.1. A cooling gas at an appropriate temperature, such as recirculated flue gas consisting mainly of carbon dioxide, can circulate within the cooling chamber or jacket 48.1. The heat shield 48 in Figure 9 can be made of a nickel-based alloy, and the low-pressure exhaust casing 41.2 can be made of ferritic-martensitic steel or austenitic steel, as in the embodiment of Figure 8.

[0068] An efficient connection between the high-pressure casing 41.1 and the low-pressure exhaust casing 41.2 can be achieved by properly formed flanges and associated connecting means. In Figure 2, the high-pressure casing 41.1 includes a high-pressure closing flange 41.5, and the low-pressure exhaust casing includes a low-pressure closing flange 41.6. The high-pressure closing flange 41.5 and the low-pressure closing flange 41.6 are joined to each other by a set of studs or bolts, which are shown in more detail and in various embodiments in Figures 10 to 21.

[0069] Referring to Figures 2 to 9, Figure 10 shows a cross-sectional view of a portion of the outer casing 41 in one embodiment. The high-pressure closing flange 41.5 and the low-pressure closing flange 41.6 are joined to each other by studs 81, each having a first threaded end that is screwed into a threaded blind hole 82 in the respective low-pressure closing flange 41.6. The studs 81 extend through the respective holes in the high-pressure closing flange 41.5, and the second threaded end of each stud 81 is engaged by a nut 83.

[0070] In some embodiments, one of the low-pressure closing flange 41.6 and the high-pressure closing flange 41.5 may have at least one ravet that cooperates with the other flange. The ravet is particularly useful in embodiments in which the high-pressure casing is made of a heat-resistant alloy that is typically characterized by a higher coefficient of thermal expansion than that of the high-pressure casing, which can be made of, for example, a martensitic alloy.

[0071] Generally, ravets can be located internally, i.e., inside the outer casing; externally, i.e., outside the outer casing; or in between. In some embodiments, two or more ravets can be provided at the interface between flanges 41.6, 41.5, and can be located on the high-pressure flange, on the low-pressure flange, or both.

[0072] In Figure 10, the low-pressure closing flange has an internal ravet 85. During operation, the ravet is driven and engaged by the higher radial displacement of the exhaust casing relative to the high-pressure casing.

[0073] Continuing to refer to Figures 2 to 10, Figure 11 shows further embodiments of the low-pressure closing flange 41.6 and the high-pressure closing flange 41.5. In this embodiment, both the low-pressure closing flange 41.6 and the high-pressure closing flange 41.5 include through holes. A set of bolts 87 and their respective nuts 88 connect the low-pressure exhaust casing 41.2 and the high-pressure casing 41.1 to each other.

[0074] Continuing to refer to Figures 2 to 11, Figure 12 shows a further embodiment of the low-pressure closing flange 41.6 and the high-pressure closing flange 41.5. The low-pressure closing flange 41.6 and the high-pressure closing flange 41.5 are joined to each other by a pair of bolts 87 extending through holes in the low-pressure closing flange 41.6 and the high-pressure closing flange 41.5. External nuts 91 are screwed onto the first ends of each bolt 87, which are located on the outside of the outer casing 41. Internal nuts 93 are screwed onto both ends of each bolt 87. Each internal nut 93 is housed in a seat 95 facing the inside of the discharge plenum 41.3. This embodiment reduces the outer diameter of the flanges while still allowing the use of standard screws and nuts.

[0075] The low-pressure closing flange 41.6 further includes an internal ravet 97 that works in cooperation with the high-pressure closing flange 41.5.

[0076] Figure 13 shows embodiments of high-pressure and low-pressure closing flanges 41.5 and 41.6 in a further embodiment similar to the embodiment in Figure 10. The same reference numerals as in Figure 10 are used in Figure 13 to indicate the same or equivalent components. The main difference between Figure 13 and Figure 10 is the position of the centered rubber. In the embodiment of Figure 13, the external rubber 86 is formed integrally with the high-pressure closing flange 41.5, replacing the internal rubber 85 which is formed integrally with the low-pressure closing flange 41.6 in Figure 10.

[0077] To improve the seal between the low-pressure closing flange 41.6 and the high-pressure closing flange 41.5, energized seals may be provided in some embodiments. Figures 14 and 15 show cross-sectional views of the outer casing 41, which includes a radially acting energized seal 101 and an axially acting energized seal 103, respectively.

[0078] In some embodiments, ribs can be provided in the exhaust plenum 41.3 to provide a more rigid structure for the low-pressure exhaust casing 41.2. Embodiments having reinforcing ribs 105 within the exhaust plenum 41.3 are shown in Figures 16, 17, and 18, where Figure 16 shows a cross-sectional view of the outer casing, and Figures 17 and 18 show detailed cross-sectional unequal-angle projections of the low-pressure exhaust casing. The reinforcing ribs 105 suppress deflection deformation of the low-pressure exhaust casing 41.2 due to the internal pressure of the exhaust flue gas. Furthermore, the reinforcing ribs 105 can improve the distribution of exhaust flue gas toward the exhaust aperture 46.

[0079] In some embodiments, the interface between the low-pressure closing flange 41.6 and the high-pressure closing flange 41.5 may be provided with locking teeth that engage with recesses on the opposite side. Embodiments of locking teeth and recesses are shown in Figures 19, 20, and 21. In this embodiment, locking teeth 107 are provided on the surface of the high-pressure closing flange 41.5, which is in pressure contact with the corresponding surface of the low-pressure closing flange 41.6, and engage with recesses 109 on the opposite surface of the low-pressure closing flange 41.6. The opposite configuration is also possible, with the high-pressure closing flange 41.5 having recesses and the low-pressure closing flange 41.6 having locking teeth.

[0080] In the embodiments disclosed above, the outer casing 41, the inner casing 5, and the rotor 43 of the inflator 3 are adapted to allow the inner casing 51 and rotor 43 to be introduced from rear to front. In other embodiments, however, the bundle including the inner casing 51 and rotor 43 may be introduced into the outer casing 41 from front to rear. Figure 22 shows a schematic cross-sectional view of the inflator 3 adapted to allow the inflator bundle to be inserted from the front, i.e., from front to rear. The same reference numerals used in the previous figures indicate the same or equivalent components in Figure 22, which are again not described in detail.

[0081] To allow the bundles to be introduced in a front-to-rear direction (i.e., in the direction of arrow f in Figure 22), the front end of the outer casing 41 includes an aperture having a diameter large enough to accommodate the inner casing 51. The combustion chamber 7.1 of the combustor 7 is introduced into its respective seat portions 41.4 once the bundles 51, 43 are housed within the outer casing 41. The front end of the outer casing 41 is then closed by a closing member 111 positioned opposite the low-pressure exhaust casing 41.2.

[0082] In some embodiments, if the combustor includes a plurality of combustion chambers 7.1 at least partially housed within an outer casing, two or more combustion chambers 7.1 may be connected to each other by flame propagation tubes housed within the body of the outer casing, specifically within the high-pressure casing 41.1. An embodiment of flame propagation tubes connecting two adjacent combustion chambers 7.1 is shown in a cross-sectional view of Figure 23. This cross-sectional view shows the combustion chambers 7.1 and the flame propagation tubes 7.2. The flame propagation tubes fluidly connect the interiors of the combustion chambers 7.1 and propagate the flame from one chamber to the other as needed, for example, during startup. More uniform operating conditions are maintained in the various combustion chambers 7.1 connected by their respective flame propagation tubes 7.2, and the risk of flame extinction in one of the combustion chambers is prevented.

[0083] 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.

[0084] Several features disclosed in combination with the embodiments of the expander described herein can be used in power generation turbomachinery having different structures. In one embodiment, for example, the low-pressure exhaust casing can be used in expanders or turbines having different casing structures, such as a horizontal split structure, rather than the barrel structure outlined above.

[0085] Therefore, a further subject of this disclosure is a casing for a power generation turbomachinery, including an emissions plenum and a plurality of emissions apertures.

[0086] In the embodiments described above, the outer casing of the expander includes a high-pressure casing and a low-pressure exhaust casing, but the novel feature of multiple exhaust apertures can be realized in turbomachinery, in which the outer casing includes two or more sections joined along a plane containing the axis of rotation, i.e., a horizontally divided casing, and the rear portion of the casing features an exhaust plenum and multiple exhaust apertures.

[0087] The exhaust aperture can be positioned radially or tangentially. In some embodiments, the exhaust aperture can be positioned around the axis of rotation or symmetrically with respect to a plane containing the axis of rotation.

[0088] In some embodiments, the discharge plenum may include reinforcing ribs such as rib 105.

[0089] A casing including an exhaust plenum and featuring multiple exhaust apertures may be monolithic, i.e., formed as a single body. In other embodiments, the casing may be divided into two or more components, parts, or sections that can be joined to each other by screw bolts, tie rods, or other reversible coupling means. If the casing is divided into two or more parts, these parts may be joined to each other along or parallel to a plane containing the rotation axis of the turbomachine.

[0090] In some embodiments, the casing housing the exhaust plenum may be part of the outer casing of the turbomachinery, for example, forming the low-pressure exhaust casing or rear section casing of a power-generating turbomachinery. The low-pressure exhaust casing or rear section casing may include flanges for connecting to the high-pressure or front section casing of the turbomachinery.

Claims

1. It is a supercritical expansion machine, outer casing and A rotor housed in the outer casing so as to rotate around the axis of rotation, Including at least one combustor, The outer casing is formed of fewer than four annular components flanged together along planes perpendicular to the axis of rotation, and the outer casing includes a high-pressure casing and a low-pressure exhaust casing connected to each other by flange connections along planes perpendicular to the axis of rotation, each annular component of the high-pressure casing is monolithic, and the flow path is completely housed within the outer casing. The low-pressure exhaust casing includes an exhaust plenum adapted to collect combustion gases expanded through a gas expansion passage, and the low-pressure exhaust casing includes at least one exhaust aperture, wherein the expander.

2. The expander according to claim 1, wherein the at least one combustor is at least partially housed in a seat within the high-pressure casing.

3. The expander according to claim 2, wherein the at least one combustor includes a plurality of combustion chambers, and the expander further includes a plurality of seating portions within the high-pressure casing, the seating portions being positioned around the rotation axis, each seating portion housing its respective combustion chamber, and preferably adjacent combustion chambers being fluidly connected to one another by their respective flame propagation tubes.

4. The expander according to any one of claims 1 to 3, wherein the outer casing is formed by two annular components flanged toward each other along a plane perpendicular to the axis of rotation, one of the annular components being a monolithic annular component forming the high-pressure casing, and the other annular component forming the low-pressure discharge casing.

5. The expander according to any one of claims 1 to 4, wherein the low-pressure exhaust casing preferably includes a main body configured as a monolithic block extending annularly around the rotating shaft.

6. The expander according to any one of claims 1 to 5, further comprising a closing member connected to the outer casing on the opposite side of the low-pressure exhaust casing.

7. The expander according to any one of claims 1 to 6, further comprising an inner casing fixedly housed within the outer casing, wherein the rotor is housed within the inner casing so as to rotate.

8. The expander according to claim 7, wherein a plurality of annular rows of fixed blades are housed within the inner casing, each annular row of rotor blades is positioned downstream of each annular row of fixed blades and together forms an axial expander stage, and the continuously arranged annular rows of fixed blades and rotor blades form a gas expansion passage, the gas expansion passage is preferably completely housed within the inner casing.

9. The inflator according to claim 7 or 8, wherein the inner casing is mechanically coupled to the outer casing by at least one connecting member positioned between the front and rear ends of the inner casing.

10. The expander according to claim 9, wherein the at least one connecting member is adapted to allow for a difference in thermal expansion between the inner casing and the outer casing.

11. The expander according to any one of claims 7 to 10, wherein the inner casing is either entirely housed within and surrounded by the high-pressure casing, or a portion of it is housed within the high-pressure casing and protrudes into the low-pressure exhaust casing.

12. The expander according to any one of claims 7 to 11, wherein the outer casing and the bundle including the inner casing and the rotor housed therein are adapted so that the bundle is introduced into the high-pressure casing in a rear-to-front direction, and the low-pressure exhaust casing includes a contact portion against which the bundle is pressed during the operation of the expander by the thrust generated by the gas expanding through the expander.

13. The inflator according to any one of claims 7 to 11, wherein the outer casing and the bundle including the inner casing and the rotor housed therein are adapted so that the bundle is introduced into the high-pressure casing from front to rear, and the high-pressure casing forms a contact portion against which the bundle is pressed during operation of the inflator by the thrust generated by the gas expanding through the inflator.

14. The inflator according to any one of claims 7 to 13, wherein the inner casing is divided into a first casing portion and a second casing portion along a plane including the axis of rotation.

15. An expander according to any one of claims 7 to 14, comprising at least one annular fluid chamber between the inner casing and the high-pressure casing, wherein the annular fluid chamber is adapted to receive a pressurized cooling fluid.

16. An expander according to any one of claims 7 to 14, comprising a plurality of annular fluid chambers between the inner casing and the high-pressure casing, wherein the plurality of annular fluid chambers are arranged continuously from front to rear and are adapted to receive pressurized cooling fluid at a pressure that gradually decreases from the upstream annular fluid chamber to the downstream annular fluid chamber.

17. The expander according to claim 16, wherein at least two continuously arranged annular fluid chambers are separated from each other by a depressurizing device or a sealing device.

18. The expander according to claim 17, wherein the continuously arranged annular fluid chambers are separated from each other by connecting members that connect the inner casing to the outer casing.

19. An expander according to any one of claims 15 to 18, comprising a cooling duct extending through the inner casing and fluid-coupled at least one annular fluid chamber to the interior of the inner casing.

20. The inflator according to any one of claims 7 to 19, wherein the inner casing includes a plurality of inner casing sections arranged continuously in a forward-to-rear direction parallel to the axis of rotation.

21. The expander according to any one of claims 1 to 20, wherein the low-pressure exhaust casing includes a plurality of exhaust apertures.

22. The expander according to claim 21, wherein the exhaust aperture is arranged in the radial or tangential direction.

23. The expander according to claim 21 or 22, wherein the exhaust aperture is arranged symmetrically around the rotation axis or with respect to a plane including the rotation axis.

24. The expander according to any one of claims 1 to 23, wherein the low-pressure exhaust casing is made of a heat-resistant alloy such as a nickel-based alloy.

25. The expander according to any one of claims 1 to 24, wherein the low-pressure exhaust casing includes an inner thermal protection section adapted to reduce heat exchange between the exhaust flow and the inner surface of the low-pressure exhaust casing.

26. The expander according to claim 25, wherein the inner thermal protection portion includes a thermal shield that at least partially covers the inner surface of the low-pressure exhaust casing.

27. The expander according to claim 26, wherein the inner thermal protection portion includes a cooling chamber that defines a flow path for a cooling fluid between the heat shield and the inner surface of the low-pressure exhaust casing.

28. The expander according to claim 26 or 27, wherein the inner thermal protection portion includes a layer of solid thermal insulation material between the thermal shield and the inner surface of the low-pressure exhaust casing.

29. The expansion machine according to any one of claims 1 to 28, wherein the at least one combustor is selected from the group consisting of a canister combustor, a cannula combustor, an annular combustor, and a double annular combustor.

30. The high-pressure casing includes a high-pressure closing flange, and the low-pressure exhaust casing includes a low-pressure closing flange, and the high-pressure closing flange and the low-pressure closing flange are connected to each other by a set of studs or bolts, and have the following features, namely: A bolt that engages with a nut located on the low-pressure exhaust casing or the high-pressure casing, At least one ravet on at least one of the low-pressure closing flange and the high-pressure closing flange, A conductive seal that acts radially, An electrically conductive seal that acts in the axial direction, Within the discharge plenum formed in the low-pressure exhaust casing, reinforcing ribs extending from the low-pressure closing flange, An expander according to any one of claims 1 to 29, comprising at least one of the following: a locking tooth protruding from the sealing surface of one of the low-pressure closing flange and the high-pressure closing flange, and engaging with a recess formed in the sealing surface of the other of the low-pressure closing flange and the high-pressure closing flange.

31. An expander according to any one of claims 1 to 30, which is adapted to receive process fluid at a pressure of 50 barA or more, preferably 100 barA or more, more preferably 150 barA or more, and more preferably 200 barA or more.

32. An expander according to any one of claims 1 to 31, which is adapted to expand a combustion gas through the gas expansion passage with a pressure drop of at least 150 bar, preferably at least 250 bar, and more preferably 250 to 400 bar.

33. An oxygen fuel combustion system comprising an expander according to any one of claims 1 to 32, and a compression system adapted to provide a flow of compressed process gas to the expander.

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