Integral gear compressor with a combination of centrifugal and positive displacement compression stages

Abstract

A compressor is provided that includes a gear system configured to be driven by a drive unit and a plurality of compression stages coupled to the gear system, the plurality of compression stages including at least one centrifugal compression stage and at least one positive displacement compression stage. Also provided is a related method. [Selected Figure] Figure 1

Description

[Technical Field]

[0001] This application claims priority to and benefit of U.S. Provisional Patent Application No. 62 / 321,016, filed April 11, 2016, entitled "Integrated Gear Compressor Having a Combination of Centrifugal and Positive Displacement Compression Stages."

[0002] The following relates to integral gear compressors, and more particularly to integral gear compressors having a centrifugal compressor stage and a positive displacement compressor stage. [Background technology]

[0003] There are various types of compressors, each with advantages and disadvantages depending on the operating conditions. For example, centrifugal compressors efficiently and reliably manage large volumes of cold gas, while positive displacement compressors can be used to manage high pressure ratios and small volumes of gas. For example, as liquefied natural gas (LNG) systems are developed, higher pressures are required to supply gas to the primary driver. The supply side of the system is cryogenic and low pressure, while the discharge side is non-cryogenic, with a higher pressure ratio and low volume. Summary of the Invention [Problem to be solved by the invention]

[0004] Therefore, there is a need for an integral gear compressor that utilizes a combination of a centrifugal compressor and a positive displacement compressor. [Means for solving the problem]

[0005] A first aspect generally relates to an integral gear compressor having a centrifugal compressor stage and a positive displacement compressor stage.

[0006] A second aspect generally relates to a compressor comprising a gear system configured to be driven by a drive unit and a plurality of compression stages coupled to the gear system, the plurality of compression stages including at least one centrifugal compression stage and at least one positive displacement compression stage.

[0007] A third aspect generally relates to an integral gear compressor having a housing including: a drive gear including a drive shaft coupled to a drive unit; a first pinion including a first pinion shaft that meshes with the drive gear at a first stage of the drive gear; a second pinion including a second pinion shaft that meshes with the drive gear at a second stage of the drive gear; a third pinion including a third pinion shaft that meshes with the drive gear on a plane different from that of the first pinion and the second pinion; and a positive displacement compression stage coupled to either (i) the first pinion shaft or (ii) the drive shaft, and a centrifugal compression stage coupled to the second pinion shaft.

[0008] A fourth aspect generally relates to a method that includes combining at least one centrifugal compression stage and at least one positive displacement compression stage within an integral gear compressor housing.

[0009] The foregoing and other features of structure and operation will be more readily understood and more fully appreciated from the following detailed disclosure taken in conjunction with the accompanying drawings, in which: [Brief explanation of the drawings]

[0010] Some of the embodiments will now be described in detail with reference to the following drawings, in which like designations refer to like elements: [Figure 1] FIG. 1 shows a schematic plan view of a first embodiment of a compressor. [Figure 2] FIG. 2 is an embodiment of the compressor shown in FIG. 1, showing a compressor having a positive displacement compression stage and multiple centrifugal compression stages. [Figure 3] FIG. 3 shows a partial cutaway view of the compressor shown in FIG. [Figure 4] FIG. 4 shows a partial cutaway detail of FIG. [Figure 5] FIG. 5 shows a cross-sectional view of the compressor shown in FIG. 2 as seen from above. [Figure 6] FIG. 6 is a cross-sectional side view of the compressor shown in FIG. [Figure 7] FIG. 7 shows a partial cutaway detail view of an alternative embodiment of the compressor shown in FIG. [Figure 8]FIG. 8 shows a cross-sectional top view of an alternative embodiment of the compressor shown in FIG. [Figure 9] FIG. 9 shows a cross-sectional side view of an alternative embodiment of the compressor shown in FIG. [Figure 10] FIG. 10 shows a schematic side view of a second embodiment of the compressor. [Figure 11] FIG. 11 shows an embodiment of the compressor shown in FIG. 10, which includes a positive displacement compression stage and multiple centrifugal compression stages. [Figure 12] FIG. 12 shows a partial cutaway view of the compressor shown in FIG. [Figure 13] FIG. 13 shows a partial cutaway detail of FIG. [Figure 14] FIG. 14 shows a cross-sectional view of the compressor shown in FIG. 10 as seen from above. [Figure 15] FIG. 15 is a cross-sectional side view of the compressor shown in FIG. [Figure 16] Figure 16 shows a schematic side view of a third embodiment of the compressor; and [Figure 17] FIG. 17 shows an embodiment of a compressor having an indirectly mounted positive displacement compression stage; and [Figure 18] FIG. 18 shows a top view of one embodiment of the compressor shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0011] The detailed description of the embodiments of the disclosed apparatus and method below is provided by way of example and not by way of limitation with reference to the drawings. Although some embodiments have been shown and described in detail, it should be understood that various changes and modifications can be made without departing from the scope of the appended claims. The scope of the present disclosure is in no way limited to the number of components, their materials, their shapes, their relative arrangements, etc., which are merely disclosed as examples of embodiments of the present disclosure.

[0012] As a preface to the detailed description, it is expressly noted that as used in this specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0013] Referring to the figures, FIG. 1 illustrates an embodiment of a compressor 100. The embodiment of the compressor 100 may be referred to as an integrally geared compressor. The compressor 100 may be used in a variety of gas compression applications, such as LNG applications for LNG power vessels, energy recovery in gas compression applications, and gas process control. The embodiment of the compressor 100 may include a combination of one or more centrifugal compressor stages with one or more positive displacement compressor stages, such as rotary screw stages. These integral compressor stages may be disposed within a single gearbox 5. System requirements may determine the configuration of the compressor 100 and / or the number of compression stages. For example, the embodiment of the compressor 100 may be a multi-stage compressor, and the system requirements may dictate the number of centrifugal compression stages according to the number or type of sections of the positive displacement compression stages.

[0014] Additionally, compressor 100 may include a gear system 1. Embodiments of gear system 1 may be integrated within or disposed in a single gear box 5. Gear box 5 may be a gear box or housing that houses, receives, supports, accommodates, etc., components of gear system 1 of compressor 100. Gear system 1 of compressor 100 includes a drive shaft 10, a drive gear 15, a first pinion shaft 20, a first pinion gear 25, a second pinion shaft 30, a second pinion gear 35, a third pinion shaft 40, and a third pinion gear 45.

[0015] An embodiment of the gear system 1 of the compressor 100 may include a drive shaft 10 and a drive gear 15. The drive gear 15 may be operably mounted on the drive shaft 10. For example, the drive gear 15 may be fixed to the drive shaft 10, such that rotation of the drive shaft 10 is converted into rotation of the drive gear 15. In other embodiments, the drive gear 15 may be structurally integral with the drive shaft 10. The drive shaft 10 may protrude from a front surface of the drive gear 15 along a central axis of the drive gear 15, or may protrude from a back surface of the drive gear 15 along the central axis of the drive gear 15. An embodiment of the drive gear 15 may include teeth along an outer circumferential surface of the drive gear 15. The gear teeth of the drive gear 15 may have various spacings, thicknesses, pitches, sizes, etc. Similarly, the size of the drive gear 15 may be varied to achieve different desired speeds, ratios, torque transmissions, etc. of the gear system 1. An embodiment of the drive gear 15 may be arranged within a gearbox 5.

[0016] Additionally, embodiments of drive shaft 10 may be driven by a drive unit 2 or drive source. The drive unit 2 or drive source may drive, rotate, or otherwise transmit torque to drive shaft 10 by a variety of methods, such as a steam turbine, an electric motor, and other methods known to those skilled in the art. When drive shaft 10 is actuated by drive unit 2, drive gear 15 meshes or mechanically engages with multiple pinions, such as first pinion gear 25, second pinion gear 35, and third pinion gear 45. Therefore, multiple pinion gears 25, 35, 45 are rotated in response to rotation of drive shaft 10 and drive gear 15, which are driven by drive unit 2.

[0017] Embodiments of the first pinion 20 may be arranged in a gearbox along with the drive gear 15 or may be otherwise disposed. In some embodiments, the first pinion 20 may be disposed to the side of the drive gear 15 along the same horizontal plane or axis as the drive gear 15. The first pinion gear 25 may be operably mounted to the first pinion shaft 20. For example, the first pinion gear 25 may be fixed to the first pinion shaft 20, such that rotation of the first pinion gear 25 is translated into rotation of the first pinion shaft 20. In other embodiments, the first pinion gear 25 may be structurally integral with the first pinion shaft 20. The first pinion shaft 20 may protrude from a front surface of the first pinion gear 25 along the central axis of the first pinion gear 25 or may protrude from a back surface of the first pinion gear 25. Embodiments of the first pinion gear 25 may include teeth along the outer circumferential surface of the first pinion gear 25. The gear teeth of the first pinion gear 25 can have various spacing, thickness, pitch, size, etc. Likewise, the size of the first pinion gear 25 may be varied to achieve different desired speeds, ratios, torque transmissions, etc. of the gear system 1.

[0018] Additionally, a compressor stage 70 may be operatively connected to each end of the first pinion shaft 20. An embodiment of the compressor stage 70 may be a centrifugal compressor. In some embodiments, a centrifugal compressor may be directly or otherwise disposed at each end of the first pinion shaft 20. For example, an impeller of the centrifugal compressor may be directly disposed at the first end 21 of the first pinion shaft 20, where gas is drawn in and compressed by the compressor 100. In an exemplary embodiment, the centrifugal compressor disposed at the first end 21 of the first pinion shaft 20 may be the first stage of compression. Similarly, an impeller of the centrifugal compressor may be directly disposed or otherwise disposed at the second end 22 of the first pinion shaft 20. In an exemplary embodiment, the centrifugal compressor disposed at the second end 22 of the first pinion shaft 20 may be the second stage of compression. Nevertheless, in further embodiments, the compression stage 70 arranged at the first end 21 and the second end 22 of the first pinion shaft 20 may include two sections of first stage compression.

[0019] The compression stages 70 arranged at the ends 21, 22 of the first pinion shaft 20 may be in communication via a pipe or conduit. For example, gas may be discharged from the discharge pipe of the compression stage 70 arranged at the first end 21 of the first pinion shaft 20 to an intake pipe associated with the compression stage 70 arranged at the second end 22 of the first pinion shaft 20. A heat exchanger, such as an intercooler, may be arranged between the discharge pipe and the intake pipe, as known to those skilled in the art.

[0020] Continuing to refer to FIG. 1 , embodiments of the second pinion gear 35 may be disposed within the housing along with the drive gear 15 or may be otherwise positioned. In some embodiments, the second pinion gear 35 may be disposed to the side of the drive gear 15 along the same horizontal plane or axis as the drive gear 15. In exemplary embodiments, the second pinion gear 35 may be located on the opposite side of the drive gear 15 from the first pinion gear 25. The second pinion gear 35 may be operably mounted on the second pinion shaft 30. For example, the second pinion gear 35 may be fixed to the second pinion shaft 30, such that rotation of the second pinion gear 35 is translated into rotation of the second pinion shaft 30. In other embodiments, the second pinion gear 35 may be structurally integral with the second pinion shaft 30. The second pinion shaft 30 may protrude from a front surface of the second pinion gear 35 along the central axis of the second pinion gear 35, or from a back surface of the second pinion gear 35 along the central axis of the second pinion gear 35. Embodiments of the second pinion gear 35 may include teeth along the outer circumferential surface of the second pinion gear 35. The gear teeth of the second pinion gear 35 may have various spacings, thicknesses, pitches, sizes, etc. Similarly, the size of the second pinion gear 35 may be varied to achieve different desired speeds, ratios, torque transmissions, etc. of the gear system 1.

[0021] Additionally, a compressor stage 70 may be operatively connected to each end of the second pinion shaft 30. An embodiment of the compressor stage 70 may be a centrifugal compressor. In some embodiments, a centrifugal compressor may be directly or otherwise disposed at each end of the second pinion shaft 30. For example, an impeller of the centrifugal compressor may be attached directly to the first end 31 of the second pinion shaft 30, in which case gas from an earlier compression stage is inducted for compression by the compressor 100. In an exemplary embodiment, the centrifugal compressor disposed at the first end 31 of the second pinion shaft 30 may be the third stage of compression. Similarly, an impeller of the centrifugal compressor may be directly or otherwise disposed at the second end 32 of the second pinion shaft 30. In an exemplary embodiment, the centrifugal compressor disposed at the second end 32 of the second pinion shaft 30 may be the fourth stage of compression.

[0022] The compression stages 70 arranged at the ends 31, 32 of the second pinion shaft 30 may be in communication via a pipe or conduit. For example, gas may be discharged from the discharge pipe of the compression stage 70 arranged at the second end 22 of the first pinion shaft 20 to a suction pipe associated with the compression stage 70 arranged at the first end 31 of the second pinion shaft 30. A heat exchanger, such as an intercooler, may be arranged between the discharge pipe and the suction pipe, as known to those skilled in the art.

[0023] Additionally, embodiments of the third pinion gear 45 may be arranged within the housing along with the drive gear 15 or may be otherwise disposed. In some embodiments, the third pinion gear 45 may be arranged along a different horizontal plane or axis than the first and second pinion gears 25, 35. In exemplary embodiments, the third pinion gear 45 may be located above or below the first and second pinion gears 25, 35. The third pinion gear 45 may be operably mounted on the third pinion shaft 40. For example, the third pinion gear 45 may be fixed to the third pinion shaft 40, such that rotation of the third pinion gear 45 is translated into rotation of the third pinion shaft 40. In other embodiments, the third pinion gear 45 may be structurally integral with the third pinion shaft 40. The third pinion shaft 40 may protrude from the front face of the third pinion gear 45 along the central axis of the third pinion gear 45, or may protrude from the back face of the third pinion gear 45. Embodiments of the third pinion gear 45 may include teeth along the outer circumferential surface of the third pinion gear 45. The gear teeth of the third pinion gear 45 may have various spacing, thickness, pitch, size, etc. Similarly, the size of the third pinion gear 45 may be varied to achieve different desired speeds, ratios, torque transmissions, etc. of the gear system 1.

[0024] Additionally, a compressor stage 70 may be operatively connected to each end of the third pinion shaft 40. An embodiment of the compressor stage 70 may be a centrifugal compressor. In some embodiments, a centrifugal compressor may be directly or otherwise disposed on each end of the third pinion shaft 40. For example, a centrifugal compressor impeller may be directly disposed on the first end 41 of the third pinion shaft 40, where gas from an earlier compression stage is inducted for compression by the compressor 100. In an exemplary embodiment, the centrifugal compressor disposed on the first end 41 of the third pinion shaft 40 may be the fifth stage of compression. Similarly, a centrifugal compressor impeller may be directly disposed on or otherwise disposed on the second end 42 of the third pinion shaft 40. In an exemplary embodiment, the centrifugal compressor disposed on the second end 42 of the third pinion shaft 40 may be the sixth stage of compression. The compression stages 70 arranged at the ends 41, 42 of the third pinion shaft 40 may be in communication with each other via pipes or conduits. For example, gas may be discharged from a discharge pipe of the compression stage 70 arranged at the second end 32 of the second pinion shaft 30 to a suction pipe associated with the compression stage 70 arranged at the first end 41 of the third pinion shaft 40. A heat exchanger, such as an intercooler, may be arranged between the discharge pipe and the suction pipe, as known to those skilled in the art. The compressed gas discharged by the final compression stage 70 may be discharged as appropriate.

[0025] Although the above compression stages are described sequentially, each stage of compression may be arranged on any pinion end of the gear system 1 of the compressor 100. Embodiments of the compressor 100 may include less than six stages of compression or more than six stages of compression, and may include fewer than three pinions and pinion shafts or more than three pinions and pinion shafts. These variations may depend on system requirements.

[0026] Furthermore, the compression stages 70 arranged at the ends of the pinion shafts do not all have to be centrifugal compression stages. An embodiment of the compressor 100 can include one or more compression stages 70 that are centrifugal compression stages, and one or more compression stages 70 can be positive displacement compression stages. For example, one or more positive displacement compression stages can be utilized as compression stages 70 where centrifugal compression stages are not used. In other words, one or more centrifugal compression stages can be replaced with positive displacement compression stages. An exemplary embodiment of a positive displacement compression stage is a rotary screw compression stage. The rotary screw compression stage can be embodied as a rotary screw module that can be directly mounted on the end of one of the pinion shafts 20, 30, 40. The rotary screw module embodiment can be one or more rotary screw stages and can include a secondary gear set to allow speed adjustment. In another embodiment, the rotary screw module can be attached using a coupling or other intermediate means.

[0027] FIG. 2 illustrates one embodiment of the compressor 100 shown in FIG. 1 , including a positive displacement compression stage 80 and multiple centrifugal compression stages 90. FIGS. 3-6 illustrate the positive displacement compression stage 80 mounted or otherwise connected (e.g., directly coupled) to the second end 42 of the third pinion 40, with the impeller of the centrifugal compression stage 90 mounted to the first end 41 of the third pinion 40. The positive displacement compression stage 80 may include one or more screws 82, a connecting means 81, and a screw transmission 83 (e.g., a secondary gear set that allows speed adjustment). FIGS. 7-9 illustrate an alternative embodiment of the compressor 100 that includes a connecting means 81a.

[0028] 5 and 8, rotation of drive gear 15 by drive unit 2 rotates third pinion gear 45, which in turn rotates third pinion shaft 40, which simultaneously actuates (rotates) compression screw 82 of positive displacement compression stage 80 and impeller of centrifugal compression stage 90. In an exemplary embodiment, positive displacement compression stage 80 is the fifth or sixth stage of compression. Positive displacement compression stage 80 may also be an earlier compression stage, or may be located in an earlier or later stage of compression.

[0029] Embodiments of compressor 100 can be used for many different applications and under a variety of conditions. Typical applications include LNG processing and management and LNG power vessels. In LNG applications, the supply side of compressor 100 (e.g., where feed or supply gas is initially drawn into compressor 100) is typically cryogenic and at low pressure. Conversely, as the gas is further compressed, it becomes higher pressure, less dense, and non-cryogenic. Thus, embodiments of compressor 100 can include a compression stage 70 represented by a centrifugal compression stage near the beginning of the compression process, and compression stage 70 can be represented by a positive displacement compression stage near the discharge side of compressor 100. Nevertheless, it is contemplated that compression stage 70 of compressor 100 can be any combination of centrifugal and positive displacement compression stages.

[0030] 10 , an embodiment of compressor 200 is shown. The embodiment of compressor 200 may share the same, substantially the same, similar, or substantially similar structure and function as compressor 100. For example, the embodiment of compressor 200 includes a gear system 201 including multiple pinions, such as a first pinion, a second pinion gear 235, and a third pinion gear 245, and multiple pinion shafts, such as a first pinion shaft (not shown), a second pinion shaft 230, a third pinion shaft 240, a drive gear 215, and a drive shaft 210. Additionally, the embodiment of compressor 200 may include multiple compression stages 270 operably attached to gear system 201, which may be disposed within a single gearbox. Nevertheless, the embodiment of compressor 200 may include a positive displacement compression stage attached to an end of drive shaft 210 opposite the end to which drive unit 202 is operably attached. For example, the rotary screw module may be mounted directly on the drive shaft 210 or may be attached using a coupling or other intermediate means. The remaining compression stages 270 may be centrifugal compression stages. In a further embodiment, positive displacement compression stages may be operably attached to the gear system 201 of the compressor 200 at additional locations, in which case the remaining compression stages 270 are not all centrifugal compression stages.

[0031] FIG. 11 illustrates an embodiment of the compressor 200 shown in FIG. 10 , including a positive displacement compression stage 280 and multiple centrifugal compression stages 290. FIGS. 12-15 illustrate the positive displacement compression stage 280 mounted or otherwise coupled (e.g., directly coupled) to a drive shaft 210. The positive displacement compression stage 280 may include one or more screws 282, a connecting means 281, and a screw transmission 283 (e.g., a secondary gear set that allows for speed adjustment). As shown in FIG. 14 , rotation of the drive gear 215 by the drive unit rotates the drive shaft 210, which in turn simultaneously activates (e.g., rotates) the compression screws 282 of the positive displacement compression stage 280 and the impellers of the centrifugal compression stage 290. In an exemplary embodiment, the positive displacement compression stage 280 may be the fifth or sixth stage of compression. The positive displacement compression stage 280 may also be an earlier compression stage, located in an earlier stage of compression, or in a later stage of compression.

[0032] Continuing to refer to the drawings, FIG. 16 illustrates one embodiment of compressor 300. Embodiments of compressor 300 may share the same, substantially the same, similar, or substantially similar structure and function as compressors 100 and 200. For example, embodiments of compressor 300 include a gear system 301 including multiple pinions, such as a first pinion, a second pinion gear 335, and a third pinion gear 345; multiple pinion shafts, such as a first pinion shaft and a second pinion shaft 330; a drive gear 315; and a drive shaft 310. Furthermore, embodiments of compressor 300 may include multiple compression stages 370 operably attached to gear system 301, and gear system 301 may be disposed within a single housing or gearbox. Nevertheless, embodiments of compressor 300 may further include additional drive gears operably connected to drive shaft 310. For example, embodiments of compressor 300 may include a first secondary gear 316 and a second secondary gear 317.

[0033] The first secondary gear 316 is arranged on the drive shaft 310 and can mesh or otherwise engage with a fourth pinion 355 operably attached to the fourth pinion shaft 350. In some embodiments, the fourth pinion gear 355 can be arranged along a different horizontal plane or axis than the drive gear 315. For example, the fourth pinion gear 355 can be arranged at a distance from the drive gear 315 in a direction directly toward the drive unit 302. The fourth pinion gear 355 can be operably mounted on the fourth pinion shaft 350. For example, the fourth pinion gear 355 is fixed to the fourth pinion shaft 350, and rotation of the fourth pinion gear 355 is converted into rotation of the fourth pinion shaft 350. In other embodiments, the fourth pinion gear 355 can be structurally integral with the fourth pinion shaft 350. The fourth pinion shaft 350 may protrude from a front surface of the fourth pinion gear 355 along a central axis of the fourth pinion gear 355. Embodiments of the fourth pinion gear 345 may include teeth along the outer circumferential surface of the fourth pinion gear 355. The gear teeth of the fourth pinion gear 355 may have various spacing, thickness, pitch, size, etc. Similarly, the size of the fourth pinion gear 355 may be varied to achieve different desired speeds, ratios, torque transmissions, etc. of the gear system 301.

[0034] Additionally, a compressor stage 370 may be operatively connected to the end 351 of the fourth pinion shaft 350. An embodiment of the compressor stage 370 may be a positive displacement compressor stage. In some embodiments, the end 351 of the fourth pinion shaft 350 may be provided with a positive displacement compressor directly or otherwise.

[0035] The second secondary gear 317 may be arranged on the drive shaft 310 and may mesh or otherwise engage with a fifth pinion gear 365 operably attached to the fifth pinion shaft 360. In some embodiments, the fifth pinion gear 365 may be arranged along a different horizontal plane or axis than the drive gear 315. For example, the fifth pinion gear 365 may be arranged at a distance from the drive gear 315 in a direction away from the drive unit 302. The fifth pinion gear 365 may be operably mounted on the fifth pinion shaft 360. For example, the fifth pinion gear 365 may be fixed to the fifth pinion shaft 360, such that rotation of the fifth pinion gear 365 is translated into rotation of the fifth pinion shaft 360. In other embodiments, the fifth pinion gear 365 may be structurally integral with the fifth pinion shaft 360. The fifth pinion shaft 360 may protrude from the face of the fifth pinion gear 365 along the central axis of the fifth pinion gear 365. Embodiments of the fifth pinion gear 365 may include teeth along the outer circumferential surface of the fifth pinion gear 365. The gear teeth of the fifth pinion gear 365 may have various spacing, thickness, pitch, size, etc. Similarly, the size of the fifth pinion gear 365 may be varied to achieve different desired speeds, ratios, torque transmissions, etc. of the gear system 301.

[0036] Additionally, a compressor stage 370 may be operatively connected to the end 361 of the fifth pinion shaft 360. An embodiment of the compressor stage 370 may be a positive displacement compressor stage. In some embodiments, the end 361 of the fifth pinion shaft 360 may be provided with a positive displacement compressor directly or otherwise.

[0037] In some embodiments, compressor 300 may also include a positive displacement compression stage operably mounted on the end of drive shaft 310 opposite the end to which drive unit 302 is mounted. Thus, embodiments of compressor 300 may include at least three positive displacement compression stages used in combination with one or more centrifugal compression stages in other compression stages 370. In further embodiments, positive displacement compression stages may be operably mounted at additional locations on gear system 301 of compressor 300, where the remaining compression stages 370 are not all centrifugal compression stages.

[0038] 17-18 show embodiments of compressors 100, 200, 300 having an indirectly mounted positive displacement compression stage 80, 280. Embodiments of the positive displacement compressor 80, 280 may be mounted to a gear system 101, 201, 301 via a pinion transmission 85 in addition to a screw transmission 83, 283.

[0039] 1-18, a method for utilizing a combination of centrifugal and positive displacement compression stages includes the following steps: providing a compressor 100, 200, 300 including a gear system 1, 201, 301 configured to be driven by a drive unit 2, 202, 302; and including a plurality of compression stages 70, 270, 370 coupled to the gear system 1, 201, 301, the plurality of compression stages 70, 270, 370 including at least one centrifugal compression stage and at least one positive displacement compression stage.

[0040] While the present disclosure has been described in connection with the specific embodiments outlined above, it is apparent that many alternatives, modifications, and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments of the present disclosure set forth above are intended to be illustrative and not limiting. Various modifications may be made without departing from the spirit and scope of the present invention, as required by the following claims. The claims provide a scope for the present invention, which should not be limited to the specific examples provided herein.

Claims

1. a gear system including a drive gear configured to be driven by a drive unit and a plurality of pinion gears rotated by the drive gear; a plurality of compression stages coupled to the gear system; Gas discharged from the first compression stage is directed to a second compression stage; the plurality of compression stages include a centrifugal compression stage which is one of the first compression stage and the second compression stage attached to a first end of a pinion shaft which rotates in response to rotation of the pinion gear, and a positive displacement compression stage which is the other of the first compression stage and the second compression stage attached to a second end of the pinion shaft, a screw transmission attached to a second end of the pinion shaft and positioned between the positive displacement compression stage and the pinion shaft; a compressor in which the screw transmission is separated from the gear system by the provision of a secondary gear set to allow speed adjustment of the positive displacement compression stage relative to the centrifugal compression stage;

2. 2. The compressor of claim 1, wherein said gear systems are disposed within a single gearbox.

3. 10. The compressor of claim 1, wherein the compressor is an integral gear compressor.

4. 2. The compressor of claim 1, wherein the gear system includes a plurality of pinion shafts, a plurality of pinion gears operatively connected to the plurality of pinion shafts, a drive gear, and a drive shaft.

5. A compressor as described in claim 1, wherein the centrifugal compression stage includes an impeller.

6. The compressor of claim 1, wherein the positive displacement compression stage comprises a rotary screw compressor.

7. 2. The integrally geared compressor of claim 1, wherein said positive displacement compression stage is indirectly mounted to said gear system.

8. a drive gear including a drive shaft coupled to a drive unit; a first pinion gear that meshes with a first side surface of the drive gear, the first pinion gear including a first pinion shaft; a second pinion gear that meshes with a second side surface of the drive gear and includes a second pinion shaft; a third pinion gear arranged along a plane different from the planes of the first pinion gear and the second pinion gear, the third pinion gear including a third pinion shaft; a positive displacement compression stage connected to a first end of the second pinion shaft by a screw transmission, the screw transmission being separated from the drive gear by a secondary gear set to allow speed adjustment between the rotational speed of an impeller of a centrifugal compression stage connected to a second end of the second pinion shaft and the rotational speed of at least one screw of the positive displacement compression stage; 1. An integral gear compressor having a gearbox comprising:

9. 9. The integral gear compressor of claim 8, wherein said positive displacement compression stage includes at least one screw.

10. 9. The integral gear compressor of claim 8, wherein said positive displacement compression stage is after a third compression stage of said integral gear compressor.

11. 9. The integral gear compressor of claim 8, wherein said positive displacement compression stage precedes a fourth compression stage of said integral gear compressor.

12. a first secondary gear disposed on the drive shaft and meshing with a fourth pinion gear operably mounted on a fourth pinion shaft; The fourth pinion shaft is connected to a positive displacement compression stage or a centrifugal compression stage.

9. The integral gear compressor of claim 8.

13. a second secondary gear disposed on the drive shaft and meshing with a fifth pinion gear operably mounted on a fifth pinion shaft; 9. The integrally geared compressor according to claim 8, wherein said fifth pinion shaft is connected to a positive displacement compression stage or a centrifugal compression stage.

14. 9. The integral gear compressor of claim 8, wherein the positive displacement compression stage is indirectly coupled to a gear system including the drive gear and the first pinion gear or the second pinion gear.

15. A method for combining a centrifugal compression stage and a positive displacement compression stage in a gearbox of an integrated gear compressor, the integrated gear compressor having a gear system including a drive gear configured to be driven by a drive unit and a plurality of pinion gears rotated by the drive gear; the drive unit includes the centrifugal compression stage mounted on a first end of a pinion shaft, and the positive displacement compression stage mounted on a second end of the pinion shaft; a screw transmission attached to a second end of the pinion shaft and positioned between the positive displacement compression stage and the pinion shaft; the screw transmission is separated from the gear system by a secondary gear set to allow speed adjustment of the positive displacement compression stage relative to the centrifugal compression stage; The method wherein gas discharged from the centrifugal compression stage is directed to the positive displacement compression stage.

16. 16. The method of claim 15, wherein the integral gear compressor comprises: a drive gear including a drive shaft coupled to the drive unit; a first pinion gear meshing with a first side of the drive gear, the first pinion gear including a first pinion shaft; a second pinion gear meshing with a second side of the drive gear, the second pinion gear including a second pinion shaft; and a third pinion gear meshing with the drive gear, the third pinion gear including a third pinion shaft, arranged along a different plane from the first pinion gear and the second pinion gear.

17. 9. The integral gear compressor of claim 8, wherein said positive displacement compression stage is after a third compression stage of said integral gear compressor.

18. 9. The integral gear compressor of claim 8, wherein said positive displacement compression stage precedes a fourth compression stage of said integral gear compressor.

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