MULTI-STAGE TURBOMACHINE SYSTEM AND METHOD FOR OPERATING IT

Description

[0001] The present invention relates to a multistage turbo machine system comprising multiple turbo machines, and to a method of f operating such multistage turbo machine system.Background

[0002] Turbo machines can be used in different applications. For example, in cryogenic applications, i.e. applications with process gases at cryogenic temperatures, e.g., plants for air separation or the like, cryogenic turbo machines like turbo expanders and / or compressors are often used. Such turbo machines typically comprise an expander impeller and / or a compressor impeller, which are fixed on a shaft.

[0003] Depending on the specific needs and applications, multiple stages of turbo machine, e.g., for compressing operating fluid, can be required. In such case multistage turbo machine systems comprising multiple turbo compressors can be used. In such multistage turbo machine system, cooling of the individual compressors or their motors can be difficult.

[0004] Documents WO 2019 / 077212 A1 and WO 2019 / 077213 A1 disclose multistage fluid compression systems comprising two compressors. Parts or fractions of operating fluid can be used for cooling purposes. In particular, WO 2019 / 077212 A1 describes a serial cooling and WO 2019 / 077213 A1 describes a parallel cooling of said two compressors or their motors. Serial cooling requires two cooling gas heat exchangers, and parallel cooling means the same level of pressure for both cavities (motor cavities or housing) of said two compressors. It is therefore an object of the present invention to provide an improved multistage fluid compression system.Disclosure of the invention

[0005] This object is achieved by providing a multistage fluid compression system and a method of operating such a multistage fluid compression system with the features of the independent claims. Embodiments of the invention are the subject of the dependent claims and of the description that follows.

[0006] The invention relates to a multistage turbo machine system, which comprises (at least) a first turbo machine with a drive unit and a second turbo machine with a drive unit. The system might comprise a third turbo machine with a drive unit, as will further be explained later. These turbo machines can be of radial or axial type; also different types in the same system might be used. Preferably, these turbo machines are of magnetic bearing type (magnetic turbo compressors). Each of these drive units can comprise a motor (e.g., an electrical motor) with a housing (or cavity). Such drive unit, typically, also comprises a gearing and / or bearings (preferably, magnetic bearings). Each of said a turbo machines can comprise or be configured as a turbo compressor. In such case, said system can be considered a multistage fluid compression system. Also, one or more of said turbo machines can (e.g., additionally) comprise or be configured as a turbo expander.

[0007] Further, such multistage turbo machine system comprises a first supply line configured to supply operating fluid to be compressed to an inlet of said first turbo machine, a second supply line configured to supply operating fluid, which is provided at an outlet of said first turbo machine, to an inlet of said second turbo machine, and a third supply line for operating fluid, which is provided at an outlet of said second turbo machine. In this way, operating fluid like gas can be supplied the first turbo machine, e.g., be compressed, then further supplied to the second turbo machine, be, e.g., further compressed and then be provided for any further use. Preferably, a first operating fluid heat exchanger is provided in said second supply line, i.e., operating fluid in said second supply line can be or is cooled by said first operating fluid heat exchanger. Preferably, also a second operating fluid heat exchanger is provided in said third supply line.

[0008] Further, said system comprises a first cooling line configured to divert part (or fraction) of operating fluid in said second supply line and supply it, as cooling fluid, to said drive unit of said first turbo machine, and a second cooling line configured to supply cooling fluid from said drive unit of said first turbo machine to said first supply line. In particular, said first cooling line is connected to said second supply line between said first operating fluid heat exchanger and said inlet of said second turbo machine. In this way, cooling of the drive unit of said first turbo machine can be provided by means of said operating fluid.

[0009] Further, said system comprises a third cooling line configured to divert part (or fraction) of operating fluid in said third supply line and supply it, as cooling fluid, to said drive unit of said second turbo machine, and a fourth cooling line configured to supply cooling fluid from said drive unit of said second turbo machine to said second supply line. Preferably, said third cooling line is connected to said third supply line after said second operating fluid heat exchanger. In this way, cooling of the drive unit of said second turbo machine can also be provided by means of said operating fluid.

[0010] A particular advantage of such specific connection of cooling lines in a multistage fluid compression system is that a single cooling fluid heat exchanger is sufficient for the entire cooling fluid used. Such cooling fluid heat exchanger is preferably provided in said second cooling line.

[0011] Preferably, said system further comprises a first sealing fluid line configured to divert part (or fraction) of operating fluid in said third supply line and supply it, as sealing fluid, to said drive unit of said first turbo machine. This allows sealing of, e.g., the gearing and / or bearing of said drive unit of said first turbo machine.

[0012] Said system preferably comprises a third turbo machine with drive unit, as mentioned above. In such case, said fourth supply line is configured to supply operating fluid, which is provided at said outlet of said second turbo machine, to an inlet of said third turbo machine. Said system further comprises a fourth supply line for operating fluid, which is provided at an outlet of said third turbo machine. Preferably, a third operating fluid heat exchanger is then provided in said fourth supply line. In addition, said system further comprises a fifth cooling line configured to divert part (or fraction) of operating fluid in said fourth supply line and supply it, as sealing and / or cooling fluid, to said drive unit of said third turbo machine. Particularly, said fifth cooling line is connected to said fourth supply line after said third operating fluid heat exchanger. Said system further comprises a sixth cooling line configured to supply sealing and / or cooling fluid from said drive of said third turbo machine to said second cooling line, preferably before said cooling fluid heat exchanger.

[0013] In this way, also the drive unit of said third turbo machine can be cooled and even sealed by means of the operating fluid, still providing and using only a single cooling fluid heat exchanger.

[0014] Advantageously, said system further comprises a second sealing line configured to divert part (or fraction) of operating fluid in said fourth supply line and supply it, as sealing fluid, to said drive unit of said second turbo machine. In this way, the drive unit of said second turbo compressor can also be sealed by means of the operating fluid, still providing and using only a single cooling fluid heat exchanger.

[0015] It is of advantage, if said third turbo machine comprises a turbo compressor and a turbo expander. In other words, a turbo compressor can be combined with a turbo expander in a turbo machine, using the same drive unit. In this case, a third sealing line can be provided, which is configured to supply sealing fluid from said drive unit of said third turbo machine to said second supply line.

[0016] Besides the advantage of using only a single cooling fluid heat exchanger as mentioned above, other advantages of the present invention are that sealing fluid like seal gas sent to the cavity (or housing) of a drive unit of a turbo machine can also be used as cooling gas (saving in term of flow consumption). No cooling fluid or gas is necessary for, in particular, magnetic, turbo machines because sealing fluid like seal gas provides sufficient cooling flow. Said first operating fluid heat exchanger can be shared for main refrigerant gas cooling and cooling gas re-cooling. Operating or cooling fluid of said second turbo machine can be let down to intermediate pressure (downstream said first turbo machine). Power can be saved in comparison with a solution when the cooling fluid or gas flow is let down to the lowest fluid or gas pressure (inlet of said first turbo machine) and recompressed up to high pressure (downstream / outlet of said second turbo machine). Since the cooling fluid lines for the different turbo machines are independent, it is possible to set two different flow values for the cooling lines depending on actual heating of the turbo machines (and, thus, avoid overconsumption).

[0017] The invention also relates to a method for operating a multistage turbo machine system like the one mentioned above in any of its embodiments. With respect to preferred embodiments and advantages, it is referred to the remarks from above, which apply correspondingly.

[0018] Further advantages and embodiments of the invention will become apparent from the description and the appended figures.Short description of the figures

[0019] Fig. 1illustrates a multistage turbo machine system according to a preferred embodiment of the invention. Fig. 2illustrates a multistage turbo machine system according to a further preferred embodiment of the invention. Detailed description of the figures

[0020] Fig. 1 schematically illustrates a multistage turbo machine system 100 according to a preferred embodiment of the invention. Said system 100 comprises a first turbo machine 110 with a drive unit 112, a second turbo machine 120 with a drive unit 122, and a third turbo machine 130 with a drive unit 132. Each of said first turbo machine 110 and said second turbo machine 120 are configured as a turbo compressor, having a compressor impeller 111 and 121, respectively. Said third turbo machine 130 comprises a turbo compressor 1138 with a compressor impeller 131 and a turbo expander 139 with a expander impeller 137.

[0021] Said drive unit 112 comprises a bearing 113 and a motor 114 in a housing or casing. Similarly, said drive unit 122 comprises a bearing 123 and a motor 124 in a housing or casing, and said drive unit 132 comprises a bearing 133 and a motor 134 in a housing or casing.

[0022] Further, said system 100 comprises a first supply line S1 configured to supply operating fluid a to an inlet of said first turbo machine 110, a second supply line S2 configured to supply operating fluid b, which is provided at an outlet of said first turbo machine 110, to an inlet of said second turbo machine 120, a third supply line S3 configured to supply operating fluid c, which is provided at an outlet of said second turbo machine 120, to an inlet of said third turbo machine 130 (the inlet of the turbo compressor 138), and a fourth supply line S4 for operating fluid d, which is provided at an outlet of said third turbo machine 130 (the outlet of the turbo compressor 138). Note that operating fluids a, b, c and d correspond to the same operating fluid at different stages of said system 100.

[0023] Said system 100 further comprises a fifth supply line S5 configured to supply operating fluid e to another inlet of said third turbo machine 130 (the inlet of the turbo expander 139), and sixth supply line S6 configured to supply operating fluid f provided at another outlet of said third turbo machine 130 (the outlet of the turbo expander 139).

[0024] Said system 100 further comprises a first operating fluid heat exchanger 115 (provided or arranged) in said second supply line S2, a second operating fluid heat exchanger 12 5(provided or arranged) in said third supply line S3, and a third operating fluid heat exchanger 135 (provided or arranged) in said fourth supply line S4.

[0025] Further, said system 100 comprises a first cooling line L1 configured to divert part of operating fluid b in said second supply line S2 and supply it, as cooling fluid g, to said drive unit 112 of said first turbo machine 110. Said first cooling line L1 is connected to said second supply line S2 between said first operating fluid heat exchanger 115 and said inlet of said second turbo machine 120. Said system 100 further comprises a second cooling line L2 configured to supply cooling fluid h from said drive unit 112 of said first turbo machine 110 to said first supply line S1. Said system 100 further comprises a cooling fluid heat exchanger 150 (arranged or provided) in said second cooling line L2.

[0026] Further, said system 100 comprises a third cooling line L3 configured to divert part of operating fluid c in said third supply line S3 and supply it, as cooling fluid k, to said drive unit 122 of said second turbo machine 120, and a fourth cooling line L4 configured to supply cooling fluid I from said drive unit 122 of said second turbo machine 120 to said second supply line S2. In this way, said cooling fluid I is re-used. No further cooling fluid heat exchanger is necessary.

[0027] Further, said system 100 comprises a fifth cooling line L5 configured to divert part of operating fluid d in said fourth supply line S4 and supply it, as sealing and / or cooling fluid m, to said drive unit 132 of said third turbo machine 130, and a sixth cooling line L6 configured to supply sealing and / or cooling fluid n from said drive unit 132 of said third turbo machine 130 to said second cooling line L2. In this way, said sealing and / or cooling fluid n is re-used. No further cooling fluid exchanger is necessary.

[0028] In said third turbo machine 130, sealing gas o and p is supplied to or arrives in said drive unit 132. Flows o and p are, typically, internal leakage flows of the turbomachine (both, on expander side and compressor side). This is a flow coming from main process flow c, e going through the expander / compressor and a small portion of the main process flow is passing behind the impeller (because of space at the top of the impeller) and going into the cavity or housing of said turbo machine or its drive unit. Further, said system 100 comprises a third sealing line G3 configured to supply sealing fluid q from said drive unit 132 of said third turbo machine 130 to said second cooling line L2. In this way, said sealing fluid p is re-used. No further cooling or other fluid exchanger is necessary.

[0029] Fig. 2 schematically illustrates a multistage turbo machine system 200 according to a further preferred embodiment of the invention. System 200 corresponds to system 100 of Fig. 1, which additionally lines and fluid flows. In the following, only these additional aspects will be described; for remaining aspects it is referred to the description of Fig. 1.

[0030] Said system 200 comprises a first sealing line G1 configured to divert part (or fraction) of operating fluid c from said third supply line S3 to supply it, as sealing fluid t, to said drive unit 112 of said first turbo machine 110. Said system 200 comprises a second sealing line G2 configured to divert part (or fraction) of cooling fluid m from said fifth cooling line L5 to supply it, as sealing fluid s, to said drive unit 122 of said second turbo machine 120. Sealing gas provided in this way can also be used for cooling purposes and be re-used afterwards.

Claims

1. A multistage turbo machine system (100, 200) comprising: a first turbo machine (110) with a drive unit (112), a second turbo machine (120) with a drive unit (122), a first supply line (S1) configured to supply operating fluid (a) to an inlet of said first turbo machine (110), a second supply line (S2) configured to supply operating fluid (b), which is provided at an outlet of said first turbo machine (110), to an inlet of said second turbo machine (120), and a third supply line (S3) for operating fluid (c), which is provided at an outlet of said second turbo machine (120), wherein said system (100) further comprises: a first cooling line (L1) configured to divert part of operating fluid (b) in said second supply line (S2) and supply it, as cooling fluid (g), to said drive unit (112) of said first turbo machine (110), and a second cooling line (L2) configured to supply cooling fluid (h) from said drive unit (112) of said first turbo machine (110) to said first supply line (S1), characterized by that said system (100) further comprises: a third cooling line (L3) configured to divert part of operating fluid (c) in said third supply line (S3) and supply it, as cooling fluid (k), to said drive unit (122) of said second turbo machine (120), and a fourth cooling line (L4) configured to supply cooling fluid (I) from said drive unit (122) of said second turbo machine (120) to said second supply line (S2).

2. The system (100, 200) of claim 1, further comprising a cooling fluid heat exchanger (150) in said second cooling line (L2).

3. The system (100, 200) of claim 1 or 2, further comprising a first operating fluid heat exchanger (115) in said second supply line (S2), wherein said first cooling line (L1) is connected to said second supply line (S2) between said first operating fluid heat exchanger (115) and said inlet of said second turbo machine (120).

4. The system (100, 200) of claim 3, wherein said fourth cooling line (L4) is connected to said second supply line (S2) between said outlet of said first turbo machine (110) and said first operating fluid heat exchanger (115).

5. The system (100, 200) of claims 3 or 4, further comprising a second operating fluid heat exchanger (125) in said third supply line (S3), wherein said third cooling line (L3) is connected to said third supply line (S3) after said second operating fluid heat exchanger (125).

6. The system (100, 200) of any one of the preceding claims, further comprising: a first sealing line (G1) line configured to divert part of operating fluid in said third supply line (S3) and supply it, as sealing fluid (t), to said drive unit (112) of said first turbo machine (110).

7. The system (100, 200) of any one of the preceding claims, wherein said first turbo machine (110) and / or said second turbo machine (120) is configured as or comprises a turbo compressor.

8. The system (100, 200) of any one of the preceding claims, further comprising: a third turbo machine (130) with a drive unit (132), wherein said third supply line (S3) is configured to supply operating fluid (c), which is provided at said outlet of said second turbo machine (120), to an inlet of said third turbo machine (130), and a fourth supply line (S4) for operating fluid (d), which is provided at an outlet of said third turbo machine (130), wherein said system (100) further comprises: a fifth cooling line (L5) configured to divert part of operating fluid (d) in said fourth supply line (S4) and supply it, as sealing and / or cooling fluid (m), to said drive unit (132) of said third turbo machine (130), and a sixth cooling line (L6) configured to supply sealing and / or cooling fluid (n) from said drive unit (132) of said third turbo machine (130) to said second cooling line (L2).

9. The system (100, 200) of clam 8, further comprising a third operating fluid heat exchanger (135) in said fourth supply line (S4), wherein said fifth cooling line (L5) is connected to said fourth supply line (S4) after said third operating fluid heat exchanger (135).

10. The system (100, 200) of claim 8 or 9, further comprising: a second sealing line (G2) configured to divert part of operating fluid (d) in said fourth supply line (S4) or of cooling and / or sealing fluid (m) in said fifth cooling line (L5) and supply it, as sealing fluid (s), to said drive unit (122) of said second turbo machine (120).

11. The system (100, 200) of any one of claims 8 to 10, wherein said third turbo machine (130) comprises a turbo compressor (130) and, preferably, a turbo expander (138).

12. The system (100, 200) of claim 11, further comprising: a third sealing line configured to supply sealing fluid from said drive unit (132) of said third turbo compressor (130) to said second supply line (S2).

13. A method for operating a multistage turbo machine system (100, 200) wherein said system (100, 20) comprises a first turbo machine (110) with a drive unit (112), a second turbo machine (120) with a drive unit (122), wherein the method comprises: Supplying supply operating fluid (a) to an inlet of said first turbo machine (110), Supplying operating fluid (b), which is provided at an outlet of said first turbo machine (110), to an inlet of said second turbo machine (120), Providing operating fluid (c) at an outlet of said second turbo machine (120), Diverting part of operating fluid (b) provided at said outlet of said first turbo machine (110) and supplying it, as cooling fluid (g), to said drive unit (112) of said first turbo machine (110), Supplying cooling fluid (h) from said drive unit (112) of said first turbo machine (110) to said operating fluid (a), which is supplied to said inlet of said first turbo machine (110), Diverting part of operating fluid (c) provided at said outlet of said second turbo machine (120) and supplying it, as cooling fluid (k), to said drive unit (122) of said second turbo machine (120), and Supplying cooling fluid (I) from said drive unit (122) of said second turbo machine (120) to said operating fluid (b) provided at said outlet of said first turbo machine (110).

14. The method of claim 13, using said multistage turbo machine system (100, 200) of any one of claims 1 to 12.