Turbine

Abstract

A turbomachine comprises: a first stage (101) comprising a first radial impeller (103); a second stage (102) comprising a second radial impeller (104); a connection channel (109) configured to form a fluid transfer connection between the first stage and the second stage; a shaft (110) attached to the first radial impeller and the second radial impeller; and a bearing assembly (111) axially located between the first radial impeller and the second radial impeller and configured to support the shaft. A back surface of the first radial impeller faces the bearing assembly and a back surface of the second radial impeller faces away from the bearing assembly. A frame portion (113) surrounding and mechanically supporting the bearing assembly forms an inner wall of an annular channel (112) having an axial fluid transfer connection with the second radial impeller.

Description

Technical Field

[0001] The present disclosure relates to a turbine comprising at least two radial impellers located on the same shaft. Furthermore, the present disclosure relates to an electric turbine and a gas turbine system. Background Art

[0002] In a turbomachine, a fluid interacts with the blades of one or more impellers to transfer energy between the fluid and the one or more impellers. A turbomachine may be a compressor, a blower, or a pump, in which one or more impellers are used to increase the pressure and / or flow of a fluid. Alternatively, a turbomachine may be a turbine in which one or more impellers are used to receive energy from a fluid. The fluid may be a gas or a liquid, such as, for example, air, combustion gases, steam, or water.

[0003] In a radial turbo compressor, a fluid is received via an axial passage that directs the fluid axially to a radial impeller. The radial impeller is configured to rotate in a housing that directs the fluid from the outer periphery of the radial impeller to a passage for discharging the fluid. The housing typically constitutes a volute that surrounds the radial impeller and whose cross-sectional flow area increases toward an outlet that is typically tangentially directed. The housing may further constitute a diffuser that converts the kinetic energy of the fluid into pressure by gradually slowing the velocity of the fluid.

[0004] In many turbines, it is advantageous, or even necessary, to have more than one turbine stage, each operating at its own pressure range. It is straightforward to implement two or more turbine stages using two or more rotating shafts, but this approach is generally too expensive for small systems where cost-effectiveness is required. Therefore, a typical two-stage radial turbocompressor includes two radial impellers located on the same shaft to achieve a simple and robust construction. In a typical radial turbocompressor, the inlet channel is particularly sensitive to pressure and / or flow distortions that affect efficiency. Therefore, a challenge associated with a radial turbocompressor having two radial impellers on the same end of the shaft is that the shaft must pass through the inlet channel of one of the two compressor stages, and therefore the inlet channel cannot be designed as freely as the inlet channel of the other compressor stage, so that the efficiency of the first mentioned compressor stage will be lower than the efficiency of the other compressor stage. Summary of the invention

[0005] A simplified summary is provided below to provide a basic understanding of some aspects of various invention embodiments. The summary is not an extensive overview of the present invention. It is neither intended to identify the key or important elements of the present invention nor to delimit the scope of the present invention. The following summary merely presents some concepts of the present invention in a simplified form as a prelude to a more detailed description of exemplary embodiments of the present invention.

[0006] In this document, the word "geometry" when used as a prefix refers to a geometric concept that is not necessarily part of any physical object. A geometric concept can be, for example, a geometric point, a straight or curved geometric line, a geometric plane, a non-planar geometric surface, a geometric space, or any other zero-, one-, two-, or three-dimensional geometric entity.

[0007] According to the invention, a new turbomachine is provided, which turbomachine may be, for example, a turbocompressor, a pump or a blower.

[0008] The turbine according to the present invention comprises:

[0009] a first stage comprising a first radial impeller, a first channel having an axial fluid-transfer connection with the first radial impeller, and a second channel having a radial fluid-transfer connection with the first radial impeller at its outer periphery;

[0010] a second stage comprising a second radial impeller, a third channel having an axial fluid-transfer connection with the second radial impeller, and a fourth channel having a radial fluid-transfer connection with the second radial impeller at its outer periphery;

[0011] - a connecting channel configured to form a fluid-transmitting connection between the second channel and the third channel;

[0012] - a shaft to which the first radial impeller and the second radial impeller are attached; and

[0013] - A bearing assembly located axially between the first radial impeller and the second radial impeller and configured to support the shaft.

[0014] The first and second radial impellers are mounted such that: the back surface of the first radial impeller faces the bearing assembly, and the back surface of the second radial impeller faces away from the bearing assembly. The third channel has an annular portion, which constitutes an axial fluid transmission connection with the second radial impeller. The frame portion surrounding and mechanically supporting the bearing assembly constitutes the inner wall of the annular portion of the third channel, so that the inner diameter of the annular portion of the third channel surrounding the bearing assembly is the inner diameter of the blade area of ​​the second radial impeller.

[0015] Since the inner diameter of the above-mentioned annular channel portion and thus the inner diameter of the blade area of ​​the second radial impeller is so large that the bearing assembly can be surrounded by the annular channel portion, the annular channel portion can be substantially unaffected by shapes that are unfavorable from the perspective of flow characteristics, such as changes in the inner diameter. Therefore, the annular channel portion can be designed to have favorable flow characteristics. Therefore, in a turbine having two compressor stages, which have radial impellers on the same end of the shaft and the shaft passing through the inlet channel of one of the two compressor stages, the inlet channel can be designed to have favorable flow characteristics.

[0016] According to the present invention, there is also provided a new electric turbine, which may be, for example, a turbine generator.

[0017] The electric turbine according to the present invention comprises:

[0018] - a compressor stage, which is a turbine according to the invention;

[0019] - an electric machine having a stator and a rotor; and

[0020] A turbine stage having a turbine wheel.

[0021] The rotor of the electric machine is mechanically connected to a rotating component of the compressor stage, and the turbine wheel is mechanically connected to the rotor of the electric machine.

[0022] According to the present invention, there is also provided a new gas turbine system, the gas turbine system comprising:

[0023] an electric turbine according to the invention and comprising a compressor stage, an electric motor and a turbine stage, the compressor stage being configured to compress air, the turbine stage being configured to drive the electric motor and the compressor stage; and

[0024] - a combustion chamber configured to receive fuel and compressed air, to combust the fuel and to supply combustion gases to the turbine stage.

[0025] Exemplary and non-limiting embodiments are described in the accompanying dependent claims.

[0026] Various exemplary and non-limiting embodiments, both as to constructions and methods of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific exemplary and non-limiting embodiments when read in connection with the accompanying drawings.

[0027] The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the presence of unrecited features. Furthermore, it will be understood that the use of "a" or "an" (ie the singular) in this document does not exclude a plurality.

[0028] Unless explicitly stated otherwise, the features recited in the dependent claims are mutually freely combinable. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Exemplary and non-limiting embodiments and their advantages are explained in more detail below by way of example and with reference to the accompanying drawings, in which:

[0030] Figure 1 shows a turbine according to an exemplary and non-limiting embodiment,

[0031] Figure 2 An electric turbine according to an exemplary and non-limiting embodiment is shown, and

[0032] Figure 3 A gas turbine system is shown according to an exemplary and non-limiting embodiment. DETAILED DESCRIPTION

[0033] The specific examples provided in the following description should not be construed as limiting the scope and / or applicability of the appended claims.The lists and groups of examples provided in the description are not exhaustive unless expressly stated otherwise.

[0034] Figure 1 A turbine according to an exemplary and non-limiting embodiment is shown. Figure 1The cross-section view is shown so that the geometrical cutting plane is parallel to the yz plane of the coordinate system 199. The turbine comprises a first stage 101 comprising: a first radial impeller 103; a first passage 105 having an axial fluid transfer connection with the first radial impeller 103; and a second passage 106 having a radial fluid transfer connection with the first radial impeller 103 at the outer periphery of the first radial impeller 103. In this exemplary case, the second passage 106 comprises a diffuser for receiving air or some other fluid from the first radial impeller 103 and a volute for receiving said air or some other fluid from the diffuser. The turbine includes a second stage 102 including: a second radial impeller 104; a third passage 107 having an axial fluid transfer connection with the second radial impeller 104; and a fourth passage 108 having a radial fluid transfer connection with the second radial impeller 104 at the outer periphery of the second radial impeller 104. In this exemplary case, the fourth passage 108 includes a diffuser for receiving air or some other fluid from the second radial impeller 104 and a volute for receiving the air or some other fluid from the diffuser.

[0035] The turbine comprises a connecting passage 109 which is configured to form a fluid transfer connection between the second passage 106 and the third passage 107, i.e. to form a series connection between the first stage 101 and the second stage 102 of the turbine. Figure 1 In the figure, only the connecting channel 109 is schematically shown.

[0036] The turbine further includes a shaft 110, to which the first radial impeller 103 and the second radial impeller 104 are attached, and a bearing assembly 111, which is axially located between the first radial impeller 103 and the second radial impeller 104 and is configured to support the shaft 110. In a turbine according to an exemplary and non-limiting embodiment, the bearing assembly 111 may be, for example, a commercial bearing cartridge designed for a turbocharger. In a turbine according to another exemplary and non-limiting embodiment, the bearing assembly 111 may include one or more active magnetic bearings "AMBs".

[0037] like Figure 1As shown in , the first radial impeller 103 and the second radial impeller 104 are installed so that the back surface of the first radial impeller 103 faces the bearing assembly 111, and the back surface of the second radial impeller 104 faces away from the bearing assembly 111. The above-mentioned third channel 107 has an annular portion 112, which constitutes an axial fluid transmission connection with the second radial impeller 104. The frame portion 113 surrounding and mechanically supporting the bearing assembly 111 constitutes the inner wall of the annular portion 112 of the third channel 107. Since the inner diameter D1 of the above-mentioned annular portion 112 (which is also the inner diameter of the blade area of ​​the second radial impeller 104) is so large that the bearing assembly 111 can be surrounded by the annular portion 112, the annular portion 112 can be substantially unaffected by unfavorable shapes (such as changes in the inner diameter, etc.) from the perspective of flow technical characteristics. Although the flow must make a 90-degree direction change in the boundary area between the annular portion 112 and the rest of the third channel 107, the third channel 107 can be designed so that the pressure loss in the third channel 107 can be low, for example 1%. like Figure 1 As shown in , the structure constituting the wall of the third passage 107 and the frame portion 113 surrounding and mechanically supporting the bearing assembly 111 form part of the turbine body.

[0038] like Figure 1 As shown in , the portion of the second radial impeller 104 located inside the diameter D1 is significant relative to the portion of the second radial impeller 104 including the blades of the second radial impeller 104. Therefore, the second radial impeller 104 has been designed to receive fluid from the annular axial channel, i.e. from the annular portion 112, the inner diameter D1 of which is significant relative to the outer diameter D2 of the second radial impeller 104. In a turbine according to an exemplary and non-limiting embodiment, the ratio of the diameter D1 to the diameter D2 (i.e. D1 / D2) is in the range from 0.6 to 0.8. In a turbine according to an exemplary and non-limiting embodiment, the ratio D1 / D2 is in the range from 0.7 to 0.8. Note that in a turbine according to an exemplary and non-limiting embodiment (whose capacity is higher than in Figure 1 In the case of the turbine capacity shown in ), the outer diameter D2 of the second radial impeller may be so large that the ratio D1 / D2 is less than the above-mentioned 0.6.

[0039] In a turbine according to an exemplary and non-limiting embodiment, the frame portion 113 has a pressure balance passage 114 that connects a first space between the back surface of the first radial impeller 103 and the frame portion 113 to a second space between the frame portion 113 and the axially facing front surface of the second radial impeller 104. The pressure balance passage 114 eliminates or at least reduces the axial pressure difference on the frame portion 113. This axial pressure difference may be harmful because it may cause fluid flow through the bearing assembly 111, and thus lubricating oil may enter the second passage 106. Figure 1 One pressure equalization channel 114 is shown, but it is obvious that there may also be two or more pressure equalization channels.

[0040] exist Figure 1 In the exemplary turbine shown in , the frame portion 113 includes an inlet oil passage 116 for supplying lubricating oil to the bearing assembly 111 and an outlet oil passage 117 for allowing the lubricating oil to flow out of the bearing assembly 111 .

[0041] exist Figure 1 In the exemplary turbine shown in FIG. 1 , the front surface of the second radial impeller 104 has an annular collar portion 115 that is concentric with the shaft 110 and has radially facing side surfaces that are configured to radially face the radially facing surface of the frame portion 113. Figure 1 In the exemplary case shown in , the radially facing side surface of the annular collar portion 115 includes grooves to provide a labyrinth seal effect to reduce leakage.

[0042] In a turbine according to an exemplary and non-limiting embodiment, the connecting passage 109 between the first stage 101 and the second stage 102 includes an intercooler 118 .

[0043] Figure 2 An electric turbine according to an exemplary and non-limiting embodiment is shown. Figure 2 The cross-section view is shown so that the geometrical cutting plane is parallel to the yz plane of the coordinate system 299. The electric turbine comprises a compressor stage 221, which is a turbine according to one embodiment of the invention. The compressor stage 221 may be, for example, a Figure 1 The electric turbine comprises an electric machine 222 having a stator 224 and a rotor 225. The electric machine may be, for example, an induction machine, a permanent magnet synchronous machine, an electrically excited synchronous machine or a reluctance machine. The stator 224 may be provided with liquid cooling, for example, such that the stator 224 is cooled by an oil circuit. The rotor 225 may be cooled by air or some other suitable gas. Figure 2 The air flow for cooling the rotor 225 is depicted by dashed arrows.

[0044] The electric turbine includes a turbine stage 223 having a turbine wheel 226. In this exemplary electric turbine, a rotor 225 of the motor 222 is supported by a bearing assembly 214 of the compressor stage 221 and a bearing assembly 227 of the turbine stage 223. The bearing assembly 227 of the turbine stage 223 may be similar to the bearing assembly 214 of the compressor stage 221. In an electric turbine according to an exemplary and non-limiting embodiment, the bearing assembly 214 and the bearing assembly 227 may be commercial bearing cartridges designed, for example, for turbochargers.

[0045] exist Figure 1 In the exemplary electric turbine shown in , the stator 224 of the motor 222 includes a drum winding 227 having a first coil side located in a slot of the stator core and a second coil side located on a yoke of the stator core. In many low power applications, the number of pole pairs of the motor 222 is advantageously 1, in which case the drum winding provides a shorter end winding than a winding in which all coil sides are in the slots of the stator core.

[0046] Figure 3 A gas turbine system according to an exemplary and non-limiting embodiment is shown. The gas turbine system includes an electric turbine 330 according to an embodiment of the present invention. The electric turbine 330 may be, for example, Figure 2 The electric turbine 330 includes a compressor stage, an electric motor, and a turbine stage, the compressor stage being configured to compress air, and the turbine stage being configured to drive the electric motor and the compressor stage. Figure 3 In FIG. 3 , the electric turbine 330 is shown in cross-section such that the geometric cutting plane is parallel to the yz plane of the coordinate system 399. The gas turbine system includes a combustion chamber 331 configured to receive compressed air and fuel from the compressor stage of the electric turbine 330. The combustion chamber 331 is configured to combust the fuel and supply the resulting combustion gas to the turbine stage of the electric turbine 330. Figure 3 The combustion chamber 331 is only schematically presented in FIG. The electric machine of the electric turbine is connected to the electric power system 333 to supply electric power to the electric power system 333. Figure 3 In the exemplary case shown in , the power system 333 comprises a frequency converter and an AC voltage grid. It is also possible that the electric machine of the gas turbine system according to an embodiment of the invention is connected to a power system which may comprise, for example, a controlled rectifier and a battery.

[0047] According to an exemplary and non-limiting embodiment, the gas turbine system includes a heat exchanger 332, which is configured to: receive combustion gases from the turbine stage; receive compressed air from the compressor stage; transfer heat from the combustion gases to the compressed air; and supply the heated compressed air to the combustion chamber 331.

[0048] In a gas turbine system according to an exemplary and non-limiting embodiment, the compressor stage of the electric turbine 330 includes an intercooler 318 .

[0049] The heat exchanger 332 and intercooler 318 described above improve the efficiency of the gas turbine system.

[0050] The specific examples provided in the description given above should not be construed as limiting the scope and / or applicability of the appended claims.The lists and groups of examples provided in the description given above are not exhaustive unless expressly stated otherwise.

Claims

1. A turbine, comprising: a first stage (101), the first stage (101) comprising a first radial impeller (103), a first channel (105) having an axial fluid transfer connection with the first radial impeller, and a second channel (106) having a radial fluid transfer connection with the first radial impeller at its outer periphery; a second stage (102), said second stage (102) comprising a second radial impeller (104), a third channel (107) having an axial fluid transfer connection with said second radial impeller, and a fourth channel (108), said third channel (107) having an axial fluid transfer connection with said second radial impeller at its outer periphery, and said fourth channel (108) having a radial fluid transfer connection with said second radial impeller; - a connecting channel (109) configured to form a fluid-transmitting connection between the second channel (106) and the third channel (107); - a shaft (110) to which the first radial impeller and the second radial impeller are attached; and a bearing assembly (111) located axially between the first radial impeller and the second radial impeller and configured to support the shaft, wherein the back surface of the first radial impeller faces the bearing assembly, and the back surface of the second radial impeller faces away from the bearing assembly, and the third channel (107) has an annular portion (112), the annular portion (112) constitutes an axial fluid transfer connection with the second radial impeller, and a frame portion (113) surrounding and mechanically supporting the bearing assembly constitutes an inner wall of the annular portion of the third channel, characterized in that the inner diameter (D1) of the annular portion of the third channel surrounding the bearing assembly is the inner diameter of the blade area of ​​the second radial impeller.

2. The turbine according to claim 1, wherein: A ratio of an inner diameter (D1) of the annular portion of the third passage to an outer diameter (D2) of the second radial impeller is in the range from 0.6 to 0.

8.

3. The turbine according to claim 2, wherein: The ratio ranges from 0.7 to 0.

8.

4. The turbine according to any one of claims 1 to 3, wherein: The frame portion (113) of the inner wall of the annular portion (112) constituting the third channel (107) has a pressure balancing channel (114), which connects a first space between the back surface of the first radial impeller and the frame portion to a second space between the frame portion and the axially facing front surface of the second radial impeller.

5. The turbine according to any one of claims 1 to 4, wherein: The front surface of the second radial impeller (104) has an annular collar portion (115), which is concentric with the shaft and protrudes axially toward the first radial impeller, and the annular collar portion has a radially facing side surface, which is configured to radially face the radially facing surface of the frame portion (113).

6. The turbine according to any one of claims 1 to 5, wherein: The frame portion (113) includes an inlet oil passage (116) for supplying lubricating oil to the bearing assembly (111) and an outlet oil passage (117) for allowing the lubricating oil to flow out of the bearing assembly.

7. A turbine according to any one of claims 1 to 6, wherein: The connecting passage (109) includes an intercooler (118).

8. An electric turbine comprising: - compressor stage (221); - an electric motor (222) having a stator (224) and a rotor (225); and a turbine stage (223) having a turbine wheel (226), wherein the rotor (225) of the electric machine is mechanically connected to a rotating part of the compressor stage and the turbine wheel (226) is mechanically connected to the rotor of the electric machine, wherein the compressor stage is a turbine according to any one of claims 1 to 7.

9. The electric turbine according to claim 8, wherein: The stator (224) of the electric machine includes a drum winding (227).

10. A gas turbine system comprising: - an electric turbine (330) comprising a compressor stage, an electric motor and a turbine stage, the compressor stage being configured to compress air, the turbine stage being configured to drive the electric motor and the compressor stage; as well as a combustion chamber (331) configured to receive fuel and compressed air, to combust the fuel and to supply combustion gases to the turbine stage, Characterized in that the electric turbine is the electric turbine according to claim 8 or 9.

11. The gas turbine system according to claim 10, wherein: The gas turbine system includes a heat exchanger (332) configured to: receive the combustion gas from the turbine stage; receive the compressed air from the compressor stage; transferring heat from the combustion gases to the compressed air; The heated compressed air is supplied to the combustion chamber.

12. The gas turbine system according to claim 10 or 11, wherein: The compressor stage of the electric turbine (330) includes an intercooler (318).

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