Multistage centrifugal compressor

Abstract

To provide a multi-stage centrifugal compressor which comprises a make-up stage and a recycle stage and can improve reliability.SOLUTION: In a multi-stage centrifugal compressor 100 where a make-up stage 61 and a recycle stage 62 are stored in one casing 30, a second shift amount between the centerline of a second suction nozzle 32b of the recycle stage 62 and the center axis of a rotary shaft 2 is greater than a first shift amount between the centerline of a first suction nozzle 32a of the make-up stage 61 and the center axis of the rotary shaft 2.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a multi-stage centrifugal compressor, and particularly to the arrangement of suction nozzles of a synthesis gas multi-stage centrifugal compressor used for the synthesis of ammonia, methanol, and the like.

Background Art

[0002] An example of a synthesis gas multi-stage centrifugal compressor is disclosed in Patent Document 1. As in Patent Document 1, a conventional synthesis gas multi-stage centrifugal compressor for ammonia, methanol, etc. has a makeup stage in a line for sending the gas pressurized to a predetermined pressure into a reactor, and a recycle stage in a recycle line for sending the gas that could not be completely synthesized in the reactor back to the reactor again.

[0003] In Patent Document 1, a structure is proposed in which two rows of guide vanes composed of fixed vanes and static vanes with adjustable angles are installed in the suction flow path of the recycle stage, and the swirling component is adjusted so that the gas flows in at an appropriate angle.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The inventors of the present invention designed the head of the recycle stage to be lower than the head of the makeup stage because the purpose of the makeup stage is to increase the pressure of the gas and the purpose of the recycle stage is to send out the high-pressure gas. Specifically, the make-up stage and the recycle stage, housed within a single multi-stage centrifugal compressor, have their impellers mounted on a common rotating shaft. While maintaining the same rotational speed, it's necessary to create differences in the heads of each line. Therefore, a difference in the impeller diameters was created, making the outer diameter of the recycle stage impeller smaller than that of the make-up stage impeller.

[0006] However, reducing the outer diameter of the impeller in the recycling stage resulted in insufficient flow path length for the impeller blades, leading to a decrease in intake efficiency.

[0007] As shown in Patent Document 1, a structure in which adjustable guide vanes are installed in the suction channel may cause an increase in fluid loss due to the guide vanes redirecting the angle of the gas flow.

[0008] Therefore, the present invention aims to provide a multi-stage centrifugal compressor equipped with a make-up stage and a recycle stage, which can improve reliability. [Means for solving the problem]

[0009] To solve the above problems, the multi-stage centrifugal compressor according to the present invention is a multi-stage centrifugal compressor in which a makeup stage and a recycle stage are housed in a single casing, characterized in that the second amount of misalignment between the center line of the second suction nozzle of the recycle stage and the central axis of the rotating shaft is greater than the first amount of misalignment between the center line of the first suction nozzle of the makeup stage and the central axis of the rotating shaft. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a multi-stage centrifugal compressor equipped with a make-up stage and a recycle stage, which can improve reliability. Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] This is a meridional cross-sectional view showing the upper half of the overall configuration of a multi-stage centrifugal compressor according to Embodiment 1 of the present invention. [Figure 2] Figure 1 shows a cross-sectional view taken along the line A-A', which is a cross-sectional view of the suction passage of the make-up stage of a multi-stage centrifugal compressor. [Figure 3] Figure 1 shows a cross-sectional view taken along the line B-B', which is a cross-sectional view of the suction passage of the recycling stage of a multi-stage centrifugal compressor. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings shown below, the same reference numeral is used for identical or equivalent components, and redundant explanations are omitted as appropriate. Furthermore, the size and shape of components may be simplified or exaggerated for illustrative purposes. The following describes embodiments of the present invention with reference to the drawings. [Examples]

[0013] Figure 1 is a meridional cross-sectional view showing the upper half of the overall configuration of a multi-stage centrifugal compressor according to Embodiment 1 of the present invention. In this embodiment, a synthesis gas multi-stage centrifugal compressor is assumed as an example of a multi-stage centrifugal compressor.

[0014] As shown in Figure 1, the multi-stage centrifugal compressor 100 is generally composed of a make-up stage centrifugal impeller 11 and a recycle stage centrifugal impeller 12, which impart energy to the fluid by rotating, a rotating shaft 2 to which the make-up stage centrifugal impeller 11 and the recycle stage centrifugal impeller 12 are attached, and a casing 30.

[0015] In a synthesis gas multi-stage centrifugal compressor, a makeup stage (Make up stage) 61 for sending the gas pressurized to a predetermined pressure into the reactor and a recycle stage (Recycle stage) 62 for sending the gas that could not be completely synthesized in the reactor back to the reactor again are stored in the casing 30. In the makeup stage (Make up stage) 61, since high head is required, it is composed of a plurality of makeup (Make up) stage centrifugal impellers 11. On the other hand, in the recycle stage (Recycle stage) 62, since the required head is low, it is composed of one recycle (Recycle) stage centrifugal impeller 12.

[0016] The casing 30 is supported by the flanges 31a and 31b, and the radial bearings 34a and 34b that rotatably support the rotating shaft 2 are arranged on both ends of the rotating shaft 2.

[0017] In the multi-stage centrifugal compressor 100 configured as described above, in the makeup stage (Make up stage) 61, the fluid sucked from the suction nozzle 32a (first suction nozzle) is pressurized each time it passes through the makeup (Make up) stage centrifugal impellers 11 of each stage, reaches a predetermined pressure, and is discharged from the discharge nozzle 33a (first discharge nozzle). On the other hand, in the recycle stage (Recycle stage) 62, the fluid sucked from the suction nozzle 32b (second suction nozzle) is discharged from the discharge nozzle 33b (second discharge nozzle) after passing through the recycle (Recycle) stage centrifugal impeller 12.

[0018] Next, the arrangement method of the suction nozzle 32a (first suction nozzle) and the suction nozzle 32b (second suction nozzle) according to this embodiment will be described using FIGS. 2 and 3.

[0019] FIG. 2 is a sectional view taken along the A-A' section arrow of FIG. 1 and is a sectional view of the suction flow path of the makeup stage (Make up stage) of the multi-stage centrifugal compressor. In FIG. 2, the arrow represents the direction of the gas flow, and the white arrow represents the rotation direction of the rotating shaft 2. Figure 2 shows the suction nozzle 32a (first suction nozzle) and suction passage 4a (first suction passage) of the Make-up stage 61. As shown in Figure 2, the suction passage 4a (first suction passage) is a passage that connects the suction nozzle 32a (first suction nozzle) to the centrifugal impeller inlet 5a. The rotating shaft 2 rotates clockwise. The center line of the suction nozzle 32a (first suction nozzle) passes through the central axis of the rotating shaft 2, or a small distance h from the center line of the suction nozzle 32a (first suction nozzle). M It's off by just a bit. M The smaller the value, the more uniformly the gas flows from side to side through the suction passage 4a (first suction passage), leading to a uniform flow with less swirling component at the centrifugal impeller inlet 5a, which enables a higher head. In other words, the center line of the suction nozzle 32a (the first suction nozzle) coincides with the rotating shaft 2. To put it another way, the center line of the suction nozzle 32a (the first suction nozzle) intersects with the rotating shaft 2.

[0020] Figure 3 is a cross-sectional view taken along the line B-B' in Figure 1, showing the suction passage of the recycling stage of a multi-stage centrifugal compressor. In Figure 3, arrows indicate the direction of gas flow, and white arrows indicate the direction of rotation of the rotating shaft 2. Figure 3 shows the suction nozzle 32b (second suction nozzle) and suction passage 4b ​​(second suction passage) of the Recycle stage 62. As shown in Figure 3, the suction passage 4b ​​(second suction passage) is the passage connecting the suction nozzle 32b (second suction nozzle) to the centrifugal impeller inlet 5b. The rotating shaft 2 rotates counterclockwise. The center line of the suction nozzle 32b (second suction nozzle) is a large distance h from the center of the rotating shaft 2. R It's off. h RThe larger the swirling component, the more the gas passing through the suction passage 4b ​​(second suction passage) will be biased to the left or right, and gas with a strong swirling component will flow into the centrifugal impeller inlet 5b. At this time, by positioning the suction nozzle 32b (second suction nozzle) so that the swirling direction and the rotation direction of the centrifugal impeller 5b are the same, it is possible to reduce the head size. In other words, the center line of the suction nozzle 32b (second suction nozzle) is positioned so that it does not overlap with the rotating shaft 2. To put it another way, the center line of the suction nozzle 32b (second suction nozzle) is positioned so that it does not intersect with the rotating shaft 2.

[0021] Therefore, the suction nozzle 32a (first suction nozzle) of the Make-up stage 61 and the suction nozzle 32b (second suction nozzle) of the Recycle stage 62 are h R >>h M The configuration is such that it satisfies approximately 0. This makes it possible to achieve both a high head in the Make-up stage 61 and a low head in the Recycle stage 62 while avoiding a decrease in efficiency. In addition, since no guide vanes are used, there is no failure of the moving parts, no vibration due to interference between the impeller and guide vanes, and an increase in flow path losses can be suppressed.

[0022] As described above, this embodiment makes it possible to provide a multi-stage centrifugal compressor equipped with a make-up stage and a recycle stage, thereby improving reliability. Furthermore, it is possible to achieve both a higher head size in the makeup stage and a lower head size in the recycling stage while avoiding a decrease in efficiency. Furthermore, since guide vanes are not used in this embodiment, there is no malfunction of the movable parts, no vibration caused by interference between the impeller and guide vanes, and an increase in flow path loss can also be suppressed.

[0023] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and are not necessarily limited to those having all the configurations described. [Explanation of Symbols]

[0024] 100... Multi-stage centrifugal compressor 11…Make-up Centrifugal Impeller 12…Recycled centrifugal impeller 2… Rotating shaft 30…Casing 31, 31a, 31b… Flange 32... Suction nozzle 32a... Suction nozzle (first suction nozzle) 32b... Suction nozzle (second suction nozzle) 33…Discharge nozzle 33a…Discharge nozzle (first discharge nozzle) 33b…Discharge nozzle (second discharge nozzle) 34…Bearings 34a, 34b… Radial bearings 4… Suction channel 4a... Suction channel (first suction channel) 4b... Suction channel (second suction channel) 5, 5a, 5b... Centrifugal impeller entrance 61…Makeup section 62…Recycle section

Claims

1. A multi-stage centrifugal compressor in which the makeup stage and the recycling stage are housed in a single casing, A multi-stage centrifugal compressor characterized in that the second amount of misalignment between the center line of the second suction nozzle of the recycling stage and the central axis of the rotating shaft is greater than the first amount of misalignment between the center line of the first suction nozzle of the makeup stage and the central axis of the rotating shaft.

2. In the multi-stage centrifugal compressor according to claim 1, A multi-stage centrifugal compressor characterized in that the center line of the second suction nozzle is positioned so as not to overlap with the rotating shaft.

3. In the multi-stage centrifugal compressor according to claim 1, A multi-stage centrifugal compressor characterized in that the center line of the second suction nozzle is positioned so as not to intersect with the rotating shaft.

4. In the multi-stage centrifugal compressor according to claim 2, A multi-stage centrifugal compressor characterized in that the center line of the first suction nozzle coincides with the rotating shaft.

5. In the multi-stage centrifugal compressor according to claim 3, A multi-stage centrifugal compressor characterized in that the center line of the first suction nozzle intersects with the rotating shaft.

6. In the multi-stage centrifugal compressor according to claim 4 or claim 5, A multi-stage centrifugal compressor characterized in that the center line of the first suction nozzle passes through the central axis of the rotating shaft.

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