Multistage centrifugal compressor and compressor system

Abstract

To provide a multistage centrifugal compressor in which the axial length of a rotor can be shortened while compressor performance is improved by intermediate cooling.SOLUTION: A multistage centrifugal compressor 1 according to an embodiment includes a rotor 2, a diaphragm 5, and a casing 6. The rotor 2 includes a rotating shaft 3, and a plurality of front stage impellers 4A and a plurality of rear stage impellers 4B attached to the rotating shaft 3. The diaphragm 5 includes a suction chamber 51 on the upstream side of the front stage impellers 4A, an intermediate outflow chamber 52 on the downstream side of the front stage impellers 4A, an intermediate inflow chamber 53 on the upstream side of the rear stage impellers 4B, and a discharge chamber 54 on the downstream side of the rear stage impellers 4B. The casing 6 includes a plurality of intermediate outflow ports 62 communicating with the intermediate outflow chamber 52, and a plurality of intermediate inflow ports communicating with the intermediate inflow chamber 53.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a multi-stage centrifugal compressor that compresses a working gas using a plurality of impellers, and a compressor system including the multi-stage centrifugal compressor. [Background technology]

[0002] Conventionally, multi-stage centrifugal compressors that compress working gas using multiple impellers have been known. For example, Patent Document 1 discloses a multi-stage centrifugal compressor that can cool the working gas during compression.

[0003] Specifically, the multi-stage centrifugal compressor of Patent Document 1 includes a rotor, a diaphragm that is penetrated by the rotor, and a casing that houses the diaphragm. In Patent Document 1, the diaphragm is called an "inner bundle."

[0004] The rotor includes a rotating shaft and three front impellers and two rear impellers attached to the rotating shaft. The diaphragm includes a suction chamber upstream of the front impellers, an intermediate outlet chamber downstream of the front impellers, an intermediate inlet chamber upstream of the rear impellers, and a discharge chamber downstream of the rear impellers. The casing includes an intermediate outlet communicating with the intermediate outlet chamber and an intermediate inlet communicating with the intermediate inlet chamber. In Patent Document 1, the intermediate outlet chamber and intermediate outlet are collectively referred to as the "discharge flow path," and the intermediate inlet chamber and intermediate inlet are collectively referred to as the "suction flow path."

[0005] The working gas supplied to the multi-stage centrifugal compressor is compressed by the front-stage impeller, then discharged from the multi-stage centrifugal compressor through an intermediate outlet and cooled in an intercooler. The working gas cooled in the intercooler is returned to the multi-stage centrifugal compressor through an intermediate inlet and compressed in the rear-stage compressor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-44736 Summary of the Invention [Problem to be solved by the invention]

[0007] When the working gas is continuously compressed, the temperature of the working gas rises, which increases the power required for compression and also increases the material temperature of components such as the impeller, shortening their lifespan. In contrast, if the working gas is cooled during compression, as in the multi-stage centrifugal compressor of Patent Document 1, it is possible to suppress the increase in power required for compression due to the rise in temperature of the working gas and the shortened lifespan of the impeller and other components.

[0008] However, in the multi-stage centrifugal compressor of Patent Document 1, the diameters of the intermediate outlet and the intermediate inlet are made relatively large in order to reduce pressure loss, which increases the axial length of the rotor and makes it more susceptible to problems due to axial vibration.

[0009] Therefore, an object of the present disclosure is to provide a multi-stage centrifugal compressor that can shorten the axial length of the rotor while improving compressor performance through intercooling, and a compressor system including the multi-stage centrifugal compressor. [Means for solving the problem]

[0010] From one aspect, the present disclosure provides a multi-stage centrifugal compressor that compresses a working gas using a plurality of impellers, the multi-stage centrifugal compressor comprising: a rotor including a rotating shaft and at least one front stage impeller and at least one rear stage impeller attached to the rotating shaft; a diaphragm including a suction chamber upstream of the at least one front stage impeller, an intermediate outlet chamber downstream of the at least one front stage impeller, an intermediate inlet chamber upstream of the at least one rear stage impeller, and a discharge chamber downstream of the at least one rear stage impeller; and a casing that houses the diaphragm, the casing including a plurality of intermediate outlets communicating with the intermediate outlet chamber and a plurality of intermediate inlets communicating with the intermediate inlet chamber.

[0011] From another aspect, the present disclosure provides a compressor system including: the above-described multi-stage centrifugal compressor; and a plurality of intercoolers connected to the plurality of intermediate outlets by a plurality of intermediate outlet pipes and connected to the plurality of intermediate inlet inlets by a plurality of intermediate inlet pipes. [Effects of the Invention]

[0012] According to the present disclosure, there is provided a multi-stage centrifugal compressor that can shorten the axial length of the rotor while improving compressor performance through intercooling, and a compressor system including the multi-stage centrifugal compressor. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view of a multi-stage centrifugal compressor according to one embodiment. FIG. [Figure 2] 2 is a cross-sectional view showing a compressor system including the multi-stage centrifugal compressor taken along line II-II in FIG. 1. [Figure 3] FIG. 2 is a cross-sectional view showing the compressor system taken along line III-III in FIG. [Figure 4] FIG. 10 is a cross-sectional view showing a compressor system according to a modified example. [Figure 5] FIG. 10 is a cross-sectional view showing a compressor system according to another modified example. [Figure 6] FIG. 10 is a cross-sectional view of a modified multi-stage centrifugal compressor. [Figure 7] FIG. 10 is a cross-sectional view of another modified multi-stage centrifugal compressor. DETAILED DESCRIPTION OF THE INVENTION

[0014] 1 shows a multi-stage centrifugal compressor 1 according to one embodiment. The multi-stage centrifugal compressor 1 compresses a working gas using a plurality of impellers. The working gas is not particularly limited, but may be, for example, hydrogen gas.

[0015] Furthermore, the multi-stage centrifugal compressor 1 is configured to be able to cool the working gas during compression. That is, as shown in FIG. 2, the multi-stage centrifugal compressor 1 configures a compressor system 10 together with a plurality of economizers 8. Such a compressor system 10 can achieve multi-stage compression of the working gas and cooling during compression. In this embodiment, the number of economizers 8 is two. However, the number of economizers 8 may be three or more.

[0016] In this embodiment, the axial direction of a rotor 2 (described later) is horizontal, and the multi-stage centrifugal compressor 1 is supported on a base 91 by a frame 92. However, the axial direction of the rotor 2 may be vertical.

[0017] The economizers 8 are arranged on both sides of the multi-stage centrifugal compressor 1 so as to sandwich the multi-stage centrifugal compressor 1 in a direction perpendicular to the axial direction of the rotor 2. Each economizer 8 is supported on a base 93 by a frame 94.

[0018] Returning to FIG. 1 , the multi-stage centrifugal compressor 1 includes a rotor 2, a diaphragm 5 that is inserted through the rotor 2, and a casing 6 that houses the diaphragm 5. The rotor 2 includes a rotary shaft 3, and at least one front impeller 4A and at least one rear impeller 4B that are attached to the rotary shaft 3.

[0019] In this embodiment, the rotor 2 includes four front impellers 4A and four rear impellers 4B. However, the number of front impellers 4A may be three or less, or five or more. Similarly, the number of rear impellers 4B may be three or less, or five or more.

[0020] In this embodiment, each of the front impeller 4A and the rear impeller 4B is a closed impeller in which a hub and a shroud are connected by multiple blades. The space between the hub and the shroud is divided by the blades into multiple flow passages that open in the axial and radial directions. However, each of the front impeller 4A and the rear impeller 4B may be an open impeller in which the blades protrude from the hub, and the shroud may be integrated with the diaphragm 5.

[0021] The casing 6 includes a cylindrical portion 6a extending in the axial direction of the rotor 2 and a closing portion 6b that closes one opening of the cylindrical portion 6a. The diaphragm 5 is housed within the casing 6 so that a portion of it protrudes from the other opening of the cylindrical portion 6a. The diaphragm 5 may be a single component, or may be divided into multiple segments aligned in the axial direction of the rotor 2. For ease of explanation, the direction in the axial direction of the rotor 2 in which the diaphragm 5 protrudes from the casing 6 will be referred to as the front, the side of the closing portion 6b of the casing 6 will be referred to as the rear, and the lateral direction perpendicular to the axial direction of the rotor 2 will be referred to as the left-right direction.

[0022] A holder 12 is attached to the center of the front end of the diaphragm 5, and the holder 12 holds a thrust bearing 13 that rotatably supports a flange 31 provided at the front end of the rotating shaft 3. A cover 11 that covers the front end face of the rotating shaft 3 is also attached to the holder 12. Furthermore, a holder 15 is attached to the center of the closed portion 6b of the casing 6, and radial bearings 14 and 16 that rotatably support the rotating shaft 3 are respectively held by the front of the diaphragm 5 and the holder 15.

[0023] The diaphragm 5 includes a suction chamber 51 upstream of the front impeller 4A, an intermediate outlet chamber 52 downstream of the front impeller 4A, an intermediate inlet chamber 53 upstream of the rear impeller 4B, and a discharge chamber 54 downstream of the rear impeller 4B. The suction chamber 51, the intermediate outlet chamber 52, the intermediate inlet chamber 53, and the discharge chamber 54 are all annular and centered on the axis of the rotor 2. However, the discharge chamber 54 may be spiral.

[0024] Furthermore, the diaphragm 5 includes an intake passage 5a that guides the working gas from the intake chamber 51 to the front-stage impeller 4A of the front stage, multiple return passages 5b that guide the working gas from one of the adjacent front-stage impellers 4A (the upstream front-stage impeller 4A) to the other (the downstream front-stage impeller 4A), and an intermediate outlet passage 5c that guides the working gas from the rear-stage front-stage impeller 4A to the intermediate outlet chamber 52. In this embodiment, the height of the intermediate outlet passage 5c and the height of the intermediate outlet chamber 52 in the axial direction of the rotor 2 are the same, and the intermediate outlet passage 5c and the intermediate outlet chamber 52 form a continuous passage without a step. However, the height of the intermediate outlet chamber 52 may be greater than the height of the intermediate outlet passage 5c, and a step may be formed between the intermediate outlet passage 5c and the intermediate outlet chamber 52.

[0025] The intake passage 5a includes a radially extending portion that extends radially inward from the intake chamber 51 and a curved portion that curves 90 degrees backward from the radially extending portion. A plurality of inlet guide vanes 71 are provided in the radially extending portion.

[0026] Each return flow passage 5b includes a first radially extending portion extending radially outward from the upstream front-stage impeller 4A of adjacent front-stage impellers 4A, a first curved portion bending 180 degrees backward from the first radially extending portion, a second radially extending portion extending radially inward from the first curved portion, and a second curved portion bending 90 degrees backward from the second radially extending portion. A plurality of diffuser vanes 72 are provided in the first radially extending portion, and a plurality of return vanes 73 are provided in the second radially extending portion. Note that the first radially extending portion may not be provided with a diffuser vane 72.

[0027] The intermediate outlet passage 5c extends radially outward from the final-stage front-stage impeller 4A and is connected to the intermediate outlet chamber 52 located radially outside the intermediate outlet passage 5c. The intermediate outlet passage 5c is provided with a plurality of diffuser vanes 72. Note that the intermediate outlet passage 5c may not be provided with the diffuser vanes 72.

[0028] Furthermore, the diaphragm 5 includes an intermediate inflow passage 5d that guides the working gas from the intermediate inflow chamber 53 to the front-most rear-stage impeller 4B, a plurality of return passages 5e that guide the working gas from one of the adjacent rear-stage impellers 4B (the upstream rear-stage impeller 4B) to the other (the downstream rear-stage impeller 4B), and a discharge passage 5f that guides the working gas from the final rear-stage impeller 4B to the discharge chamber 54.

[0029] The intermediate inlet flow passage 5d includes a radially extending portion that extends radially inward from the intermediate inlet chamber 53 and a curved portion that curves 90 degrees backward from the radially extending portion. A plurality of inlet guide vanes 74 are provided in the radially extending portion.

[0030] Each return flow passage 5e includes a first radially extending portion extending radially outward from the upstream rear-stage impeller 4B of the adjacent rear-stage impellers 4B, a first curved portion bending 180 degrees backward from the first radially extending portion, a second radially extending portion extending radially inward from the first curved portion, and a second curved portion bending 90 degrees backward from the second radially extending portion. A plurality of diffuser vanes 72 are provided in the first radially extending portion, and a plurality of return vanes 73 are provided in the second radially extending portion. Note that the first radially extending portion may not be provided with a diffuser vane 72.

[0031] The discharge passage 5f extends radially outward from the final rear-stage impeller 4B and is connected to the discharge chamber 54 located radially outside the discharge passage 5f. The discharge passage 5f is provided with a plurality of diffuser vanes 72. Note that the discharge passage 5f may not be provided with the diffuser vanes 72.

[0032] The casing 6 includes an intake port 61 communicating with the intake chamber 51 and an exhaust port 64 communicating with the exhaust chamber 54. The intake port 61 extends radially outward from the intake chamber 51, and the exhaust port 64 extends radially outward from the exhaust chamber 54. A tubular portion projects from the cylindrical portion 6a of the casing 6 along the intake port 61 and the exhaust port 64. However, there may be more than one intake port 61 and more than one exhaust port 64.

[0033] Furthermore, the casing 6 includes a plurality of intermediate outlets 62 communicating with the intermediate outlet chamber 52 as shown in Fig. 2 and a plurality of intermediate inlets 63 communicating with the intermediate inlet chamber 53 as shown in Fig. 3. The number of the intermediate outlets 62 and the number of the intermediate inlets 63 are the same as the number of the intercoolers 8.

[0034] Each intermediate outlet 62 extends spirally from the intermediate outlet chamber 52, and a tubular portion projects from the cylindrical portion 6a of the casing 6 along the corresponding intermediate outlet 62. In this embodiment, one intermediate outlet 62 passes to the right and below the intermediate outlet chamber 52 and opens to the left, and the other intermediate outlet 62 passes to the left and above the intermediate outlet chamber 52 and opens to the right. However, the opening direction of each intermediate outlet 62 can be changed as appropriate.

[0035] Each intermediate inlet 63 extends radially outward from the intermediate inflow chamber 53, and a tubular portion projects from the cylindrical portion 6a of the casing 6 along the corresponding intermediate inlet 63. In this embodiment, one intermediate inlet 63 opens to the left, and the other intermediate inlet 63 opens to the right. However, the opening direction of each intermediate inlet 63 can be changed as appropriate.

[0036] In the intermediate inlet chamber 53, a vane 75 is provided for each intermediate inlet 63 to spread the working gas flowing in from the intermediate inlet 63 so that the working gas flows into the intermediate inlet passage 5d from the entire circumference of the intermediate inlet passage 5d.

[0037] The economizer 8 located on the left side of the multi-stage centrifugal compressor 1 is connected to an intermediate outlet 62 that opens to the left by an intermediate outlet pipe 81, and is also connected to an intermediate inlet 63 that opens to the left by an intermediate inlet pipe 82. Similarly, the economizer 8 located on the right side of the multi-stage centrifugal compressor 1 is connected to an intermediate outlet 62 that opens to the right by the intermediate outlet pipe 81, and is also connected to an intermediate inlet 63 that opens to the right by the intermediate inlet pipe 82.

[0038] Each intercooler 8 is, for example, a heat exchanger that cools the working gas by exchanging heat between the working gas and a heat medium. The heat exchanger may be a shell-and-tube heat exchanger in which multiple tubes are arranged in a shell, or a plate heat exchanger in which corrugated plates are stacked. Alternatively, the heat exchanger may be a heat exchanger of another type.

[0039] The working gas supplied to the multi-stage centrifugal compressor 1 is guided to the front-stage impeller 4A through the suction port 61, the suction chamber 51, and the suction passage 5a and compressed. The working gas compressed in the front-stage impeller 4A is guided to the intercooler 8 through the intermediate outlet passage 5c, the intermediate outlet chamber 52, the intermediate outlet port 62, and the intermediate outlet pipe 81 and cooled. The working gas cooled in the intercooler 8 is guided to the rear-stage impeller 4B through the intermediate inlet pipe 82, the intermediate inlet port 63, the intermediate inlet chamber 53, and the intermediate inlet passage 5d and compressed. The working gas compressed in the rear-stage impeller 4B is discharged from the multi-stage centrifugal compressor 1 through the discharge passage 5f, the discharge chamber 54, and the discharge port 64.

[0040] As described above, in the multi-stage centrifugal compressor 1 of this embodiment, the working gas being compressed can be taken out of the multi-stage centrifugal compressor 1 through the intermediate outlet 62, cooled in the economizer 8, and then returned to the multi-stage centrifugal compressor 1 through the intermediate inlet 63, thereby improving compressor performance by economizing. Moreover, since a plurality of intermediate outlets 62 and intermediate inlets 63 are provided, the diameters of the intermediate outlets 62 and intermediate inlets 63 can be reduced, thereby shortening the axial length of the rotor 2. Furthermore, if the axial length of the rotor 2 is shortened, problems caused by axial vibration can be suppressed.

[0041] Incidentally, hydrogen gas is difficult to compress, and therefore the flow velocity between the multi-stage centrifugal compressor 1 and the economizer 8 increases due to the high-speed rotation of the rotor 2, and the number of impellers also tends to increase. Therefore, the effect of reducing the diameters of the intermediate outlet 62 and the intermediate inlet 63 and shortening the axial length of the rotor 2 is particularly useful when the working gas is hydrogen gas.

[0042] <Modification> The present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present disclosure.

[0043] For example, as in a modified compressor system 10A shown in Fig. 4, two intercoolers 8 may be arranged vertically on one side of the multi-stage centrifugal compressor 1. With this configuration, the space occupied by the compressor system 10A can be reduced.

[0044] Furthermore, in the compressor system 10A, the two intercoolers 8 are supported by a common frame 95. With this configuration, the cost of the compressor system 10A can be reduced.

[0045] Furthermore, as in a compressor system 10B of another modified example illustrated in FIG. 5 , when the number of intercoolers 8 is four, two intercoolers 8 lined up in the vertical direction on each of the left and right sides of the multi-stage centrifugal compressor 1 may be supported by a common frame 95.

[0046] Furthermore, like a modified multi-stage centrifugal compressor 1A shown in FIG. 6, the orientation of the rear impeller 4B may be opposite to that of the front impeller 4A.

[0047] Furthermore, a configuration in which intermediate cooling is performed twice, as in another modified multi-stage centrifugal compressor 1B shown in Fig. 7, can also be employed. In the multi-stage centrifugal compressor 1B, three intermediate stage impellers 4C are arranged between three upper stage impellers 4A and two rear stage impellers 4B. The diaphragm 5 includes an intermediate outlet chamber 52 and an intermediate inlet chamber 53 between the upper stage impeller 4A and the intermediate stage impeller 4C, and also includes an intermediate outlet chamber 52 and an intermediate inlet chamber 53 between the middle stage impeller 4C and the rear stage impeller 4B. The casing 6 includes a plurality of intermediate outlet outlets 62 for each intermediate outlet chamber 52, and a plurality of intermediate inlet ports 63 for each intermediate inlet chamber 53.

[0048] <Summary> In a first aspect, the present disclosure provides, from one aspect, a multi-stage centrifugal compressor that compresses a working gas using a plurality of impellers, the multi-stage centrifugal compressor comprising: a rotor including a rotating shaft and at least one front stage impeller and at least one rear stage impeller attached to the rotating shaft; a diaphragm including a suction chamber upstream of the at least one front stage impeller, an intermediate outlet chamber downstream of the at least one front stage impeller, an intermediate inlet chamber upstream of the at least one rear stage impeller, and a discharge chamber downstream of the at least one rear stage impeller; and a casing that houses the diaphragm, the casing including a plurality of intermediate outlets communicating with the intermediate outlet chamber and a plurality of intermediate inlets communicating with the intermediate inlet chamber.

[0049] According to the above configuration, the working gas being compressed can be taken out of the multi-stage centrifugal compressor through the intermediate outlet, cooled in the economizer, and then returned to the multi-stage centrifugal compressor through the intermediate inlet, thereby improving compressor performance through economizing. Moreover, since a plurality of intermediate outlets and intermediate inlets are provided, the diameters of the intermediate outlets and intermediate inlets can be reduced, thereby shortening the axial length of the rotor. Furthermore, a shorter axial length of the rotor can suppress problems caused by axial vibration.

[0050] As a second aspect, in the first aspect, the working gas may be hydrogen gas. Because hydrogen gas is difficult to compress, the high-speed rotation of the rotor increases the flow velocity between the multi-stage centrifugal compressor and the intercooler, and the number of impellers tends to increase. Therefore, the effect of reducing the diameters of the intermediate outlet and intermediate inlet and shortening the axial length of the rotor is particularly useful when the working gas is hydrogen gas.

[0051] As a third aspect, the present disclosure provides, from another aspect, a compressor system including: the multi-stage centrifugal compressor described above; and a plurality of intermediate coolers connected to the plurality of intermediate outlets by a plurality of intermediate outlet pipes and connected to the plurality of intermediate inlet ports by a plurality of intermediate inlet pipes.

[0052] According to the above configuration, it is possible to achieve multi-stage compression of the working gas and cooling during compression.

[0053] As a fourth aspect, in the third aspect, at least two of the plurality of intercoolers may be aligned vertically. With this configuration, the space occupied by the compressor system can be reduced.

[0054] As a fifth aspect, in the fourth aspect, the at least two intercoolers arranged vertically may be supported by a common frame. With this configuration, costs of the compressor system can be reduced. [Explanation of symbols]

[0055] 1,1A multi-stage centrifugal compressor 10, 10A, 10B Compressor System 2 rotors 3 Rotation Axis 4A Front impeller 4B rear impeller 5 diaphragm 51 Suction chamber 52 Intermediate Outflow Chamber 53 Intermediate inflow chamber 54 Discharge chamber 6 Casing 61 Intake port 62 Intermediate Outlet 63 Intermediate inlet 64 Discharge port 8 Intercooler 81 Inflow pipe 82 Outflow pipe 92, 94, 95 Mounting stand

Claims

1. A multi-stage centrifugal compressor that compresses a working gas using a plurality of impellers, a rotor including a rotating shaft and at least one front impeller and at least one rear impeller attached to the rotating shaft; a diaphragm including a suction chamber upstream of the at least one front impeller, an intermediate outlet chamber downstream of the at least one front impeller, an intermediate inlet chamber upstream of the at least one rear impeller, and a discharge chamber downstream of the at least one rear impeller; a casing that houses the diaphragm, the casing including a plurality of intermediate outlets that communicate with the intermediate outlet chamber and a plurality of intermediate inlet ports that communicate with the intermediate inlet chamber; A multi-stage centrifugal compressor comprising:

2. 2. The multi-stage centrifugal compressor according to claim 1, wherein the working gas is hydrogen gas.

3. The multi-stage centrifugal compressor according to claim 1 or 2; a plurality of intermediate coolers connected to the plurality of intermediate outlets by a plurality of intermediate outlet pipes and connected to the plurality of intermediate inlet ports by a plurality of intermediate inlet pipes; A compressor system comprising:

4. The compressor system of claim 3 , wherein at least two of the plurality of intercoolers are aligned vertically.

5. The compressor system according to claim 4 , wherein the at least two intercoolers arranged vertically are supported by a common frame.

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