WO2019160537A1

WO2019160537A1 - Modular linear reciprocating compressor

Info

Publication number: WO2019160537A1
Application number: PCT/US2018/018102
Authority: WO
Inventors: Scott J. Delmotte; Daniel Bissell; Gregory W. Yonker
Original assignee: Dresser-Rand Company
Priority date: 2018-02-14
Filing date: 2018-02-14
Publication date: 2019-08-22

Abstract

A linear motor for moving a piston rod of a reciprocating compressor. The motor includes a guidance assembly having a moveable secondary carrier that is attached to the piston rod. The motor also includes at least one permanent magnet attached to the secondary carrier and at least one primary winding attached to the guidance assembly. In addition, the motor includes a controller that controls power supplied to the primary winding to generate a magnetic field that interacts with a magnetic field generated by the permanent magnet to provide a force that moves the permanent magnet, the secondary carrier and the piston rod in a reciprocating linear motion.

Description

MODULAR LINEAR RECIPROCATING COMPRESSOR

BACKGROUND

Technical Field

[0001] Aspects of the invention relate to a linear motor for moving a piston rod of a reciprocating compressor, and more particularly, to a motor having a guidance assembly that includes a moveable secondary carrier that is attached to the piston rod wherein at least one permanent magnet is attached to the secondary carrier and at least one primary winding is attached to the guidance assembly and wherein power supplied to the primary winding is controlled to generate a magnetic field that interacts with a magnetic field generated by the permanent magnet to provide a force that moves the permanent magnet, the secondary carrier and the piston rod in a reciprocating linear motion.

Description of Related Art

[0002] A reciprocating compressor is a positive displacement machine wherein a piston moves in a reciprocating motion within a cylinder to compress and displace a gas at high pressure. Referring to Fig. 1, a schematic representation of a conventional reciprocating compressor 10 is shown. The compressor 10 includes a rotating crank mechanism 12 having a crankshaft 14, connecting rod 16, crosshead guide 18 and a piston rod 20 that is connected to a piston 22 that moves within a cylinder 24. The crank mechanism 12 converts rotary motion 26 of the crankshaft 14 into a reciprocating linear motion that drives the piston 22. Portions of the crank mechanism 12 may be housed in a compressor frame that is connected to the cylinder 24 via a structural member known as a distance piece.

[0003] Compressors are used in various industrial facilities such as oil refineries, gas transmission pipelines, chemical plants, natural gas processing plants, refrigeration plants and others. It is desirable to reduce the footprint of a compressor used in an industrial facility. It is also desirable to provide a compressor configuration that can be modified to accommodate varying process conditions, gases, and flows. SUMMARY

[0004] A linear motor for moving a piston rod of a reciprocating compressor is disclosed. The motor includes a guidance assembly having a moveable secondary carrier that is attached to the piston rod. The motor also includes at least one permanent magnet attached to the secondary carrier and at least one primary winding attached to the guidance assembly. In addition, the motor includes a controller that controls power supplied to the primary winding to generate a magnetic field that interacts with a magnetic field generated by the permanent magnet to provide a force that moves the permanent magnet, the secondary carrier and the piston rod in a reciprocating linear motion.

[0005] In another embodiment, a linear motor for moving a piston rod of a reciprocating compressor is disclosed. The motor includes a guidance assembly having a moveable secondary carrier that is attached to the piston rod, wherein the secondary carrier includes first and second wing elements. The motor also includes first and second permanent magnets attached to the first and second wing elements, respectively. In addition, the motor includes first and second primary windings located adjacent the first and second magnets, respectively, wherein the first and second primary windings are attached to the guidance assembly. Further, the motor includes a controller that controls power supplied to the first and second primary windings to generate respective magnetic fields that interact with respective magnetic fields generated by the first and second permanent magnets to provide a force that moves the first and second permanent magnets, the secondary carrier and the piston rod in a reciprocating linear motion.

[0006] Those skilled in the art may apply the respective features of the present invention jointly or severally in any combination or sub-combination. BRIEF DESCRIPTION OF DRAWINGS

[0007] The exemplary embodiments of the invention are further described in the following detailed description in conjunction with the accompanying drawings, in which:

[0008] Fig. 1 is a schematic representation of a conventional reciprocating compressor.

[0009] Fig. 2 is a view of linear motor for use in a reciprocating compressor in accordance with an aspect of the invention.

[0010] Fig. 3 depicts an alternate embodiment of the linear motor shown in Fig. 2.

[0011] Fig. 4 is a partial cross-sectional view of an embodiment of a first linear reciprocal compressor in accordance with an aspect of the invention.

[0012] Fig. 5 is an end view of the first compressor shown in Fig. 4 along view line 5- 5 of Fig. 4.

[0013] Fig. 6 depicts an alternate embodiment of a secondary carrier.

[0014] Fig. 7 is a partial cross-sectional view of an alternate embodiment for a guidance assembly located between first and second compressors.

[0015] Fig. 8 is a partial cross-sectional view of an alternate embodiment for the guidance assembly.

[0016] Fig. 9 is a partial cross sectional view of a compound linear reciprocating compressor drive in accordance with an aspect of the invention. [0017] To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. The figures are not drawn to scale.

DETAILED DESCRIPTION

[0018] Although various embodiments that incorporate the teachings of the present disclosure have been shown and described in detail herein, those skilled in the art can readily devise many other varied embodiments that still incorporate these teachings. The scope of the disclosure is not limited in its application to the exemplary embodiment details of construction and the arrangement of components set forth in the description or illustrated in the drawings. The disclosure encompasses other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,”“comprising,” or“having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms“mounted,”“connected,” “supported,” and“coupled” and variations thereof are used broadly and encompass direct and indirect mountings, connections, supports, and couplings. Further, “connected” and“coupled” are not restricted to physical or mechanical connections or couplings.

[0019] Fig. 2 is a view of linear motor 30 for use in a reciprocating compressor in accordance with an aspect of the invention. The motor 30 includes first 32 and second 34 permanent magnets, i.e. secondary magnets, which are attached to a secondary carrier 36 that is moveable along a piston rod axis 38. The secondary carrier 26 is attached to a piston rod 40 of a compressor. The piston rod 40 is attached to a piston of the compressor. At least one stationary coil element or primary winding 42 is located adjacent the first permanent magnet 32 and at least one stationary primary winding 44 is located adjacent the second permanent magnet 34. In an embodiment, first 42A, second 42B and third 42C primary windings are located adjacent the first permanent magnet 32 and fourth 44 A, fifth 44B and sixth 44C primary windings are located adjacent the second permanent magnet 34. It is understood that additional or fewer primary windings may be used.

[0020] The primary windings 42A, 42B, 42C are each spaced apart from the first 32 permanent magnet by a predetermined distance D. Similarly, the primary windings 44A, 44B, 44C are also spaced apart from the second permanent magnet 34 by the distance D. The primary windings 42A, 42B, 42C, 44A, 44B, 44C are each connected to an alternating current (AC) power source 46 that is controlled by a controller 48. In operation, the primary windings 42A, 42B, 42C, 44A, 44B, 44C are energized by the power source 46 and generate respective magnetic fields. The magnetic fields generated by the primary windings 42A, 42B, 42C, 44A, 44B, 44C interact with the magnetic fields generated by the first 32 and second 34 permanent magnets to generate a force that moves the first 32 and second 34 permanent magnets, the secondary carrier 36 and the piston rod 40 along the piston rod axis 38. In particular, the controller 48 causes the generation of magnetic fields by the primary windings 42A, 42B, 42C, 44A, 44B, 44C that cause movement of the piston rod 40 in a first direction 50 and subsequently in a second direction 52 opposite the first direction 50 to move the piston rod 40, and associated piston, in a continuous reciprocating linear motion suitable for a reciprocating compressor and at a desired operating speed.

[0021] Referring to Fig. 3, an alternate embodiment of the invention is shown. In this embodiment, a single primary winding 42D is located adjacent the first permanent magnet 32 and a single primary winding 44D is located adjacent the second permanent magnet 34. As previously described, the controller 48 causes the generation of magnetic fields by the primary windings 42D, 44D that cause movement of the piston rod 40 in a first direction 50 and subsequently in a second direction 52 opposite the first direction 50 to move the piston rod 40, and associated piston, in a continuous reciprocating linear motion suitable for a reciprocating compressor and at a desired operating speed.

[0022] Fig. 4 is a partial cross-sectional view of an embodiment of a first linear reciprocal compressor 60 in accordance with an aspect of the invention. Fig. 5 is an end view of the first compressor 60 shown in Fig. 4 along view line 5-5. Referring to Fig. 4 in conjunction with Fig. 5, the first compressor 60 includes a known compressor section 62 having a compressor inlet 64 for receiving a gas. The compressor section 62 includes a known cylinder portion 66 having inlet 68 and discharge 70 valve portions. The cylinder portion 66 includes a first moveable piston

80 (see Fig. 7) and may be either configured as a double acting cylinder or a single acting cylinder. The first compressor 60 further includes an extension piece 72 attached between the cylinder portion 66 and a guidance assembly section 74 that includes a housing 76. A moveable secondary carrier 78 is located within an interior

81 of the housing 76. The first piston 80 is attached to a first moveable piston rod 82 that extends through the extension piece 72 and is attached to the secondary carrier 78. In accordance with an aspect of the invention, the secondary carrier 78 may be attached to a piston rod of any reciprocating compressor.

[0023] The secondary carrier 78 includes a body portion 84 and first 86 and second 88 wing elements that extend from an outer surface 90 of the body portion 84. In an embodiment, the first 86 and second 88 wing elements extend from an outer diameter of the body portion 84. The first 86 and second 88 wing elements are oriented substantially horizontally and may be equally spaced from each other. The first 86 and second 88 wing elements each include first 92 and second 94 surfaces. The first 32 and second 34 permanent magnets are attached to the first 92 and second 94 surfaces, respectively. The primary windings 42A, 42B, 42C are attached to a wall 96 of the housing 76 and adjacent the first permanent magnet 32. The primary windings 44A, 44B, 44C are attached to a wall 96 of the housing 76 and adjacent the second permanent magnet 34. It is understood that additional or fewer primary windings may be used.

[0024] As previously described, the primary windings 42A, 42B, 42C and 44A, 44B, 44C are each spaced apart from the first 32 and second 34 permanent magnets, respectively, by the distance D. In an aspect of the invention, a bearing arrangement such as a linear bearing that engages the outer surface 90 of the body portion 84 may be used to maintain the distance D. In addition, the magnetic fields generated by the primary windings 42A, 42B, 42C, 44A, 44B, 44C interact with the magnetic fields generated by the first 32 and second 34 permanent magnets to generate a force that moves the first 32 and second 34 permanent magnets, the secondary carrier 78 and the first piston rod 82 along the piston rod axis 38. In particular, the first piston rod 82 moves in the first direction 50 and subsequently in the second direction 52 opposite the first direction 50 to move the first piston rod 82, and associated first piston 80, in a continuous reciprocating linear motion suitable for the first compressor 60 and at a desired operating speed.

[0025] Referring to Fig. 6, an alternate embodiment of a secondary carrier 98 is shown. In this embodiment, the secondary carrier 98 includes a body portion 84 having additional third 100 and fourth 102 wing elements that extend from the body portion 84. The third 100 and fourth 102 wing elements may be oriented substantially vertically and are located such that the first 86, second 88, third 100 and fourth 102 wing elements are equally spaced relative to each other. The third 100 and fourth 102 wing elements each include the first 92 and second 94 surfaces. First 32 and second 34 permanent magnets are attached to first 92 and second 94 surfaces, respectively, of the third 100 and fourth 102 wing elements and are thus oriented vertically. Primary windings 42A, 42B, 42C (only primary winding 42C is shown in Fig. 6) are attached to a wall 96 of the housing 76 and adjacent the first permanent magnet 32. The primary windings 44A, 44B, 44C (only primary winding 44C is shown in Fig. 6) are attached to a wall 96 of the housing 76 and adjacent the second permanent magnet 34. It is understood that additional or fewer primary windings may be used.

[0026] As previously described, the primary windings 42A, 42B, 42C and 44A, 44B, 44C are each spaced apart from the first 32 and second 34 permanent magnets, respectively, by the distance D. The primary windings 42A, 42B, 42C and 44A, 44B, 44C and adjacent first 32 and second 34 permanent magnets of the third 100 and fourth 102 wing elements generate a force that supplements the force generated by the primary windings 42A, 42B, 42C and 44A, 44B, 44C and adjacent first 32 and second 34 permanent magnets of the first 86 and second 88 wing elements to move the first piston rod 82 in a continuous reciprocating linear motion at a desired operating speed. [0027] Referring to Fig. 7, a partial cross-sectional view of an alternate embodiment for a guidance assembly 104 located between the first compressor 60 and a second linear reciprocal compressor 106. The second compressor 106 may include a known compressor section 108 having a compressor inlet 110 for receiving a gas. The compressor section 108 includes a known cylinder portion 114 having inlet 116 and discharge 118 valve portions. The cylinder portion 114 includes a second piston 122 attached to a second piston rod 120 oriented along piston rod axis 38. The second compressor 106 may also include an extension piece 124 attached between the cylinder portion 114 and the guidance assembly 104. The second piston rod 120 extends through the extension piece 124 toward the guidance assembly 104.

[0028] The guidance assembly 104 includes a moveable secondary carrier 126 located within a housing 128 of the guidance assembly 104. The secondary carrier 126 is attached between first 130 and second 132 ends of the first 82 and second 120 piston rods, respectively. The first piston rod 82 extends between a first set 83 of permanent magnets 32, 34 attached to a first side 85 of the secondary carrier 126. At least one primary winding 42, 44 is located adjacent to each permanent magnet 32, 34. In an embodiment, a first set 45 of primary windings 42A, 42B, 42C and 44A, 44B, 44C is associated with the first set 83 of permanent magnets 32, 34, respectively. The second piston rod 120 extends between a second set 121 of permanent magnets 32, 34 attached to a second side 123 of the secondary carrier 126. A second set 47 of primary windings 42A, 42B, 42C and 44A, 44B, 44C is associated with the second set 121 of permanent magnets 32, 34, respectively.

[0029] The magnetic fields generated by the first 45 and second 47 sets of primary windings 42A, 42B, 42C, 44A, 44B, 44C interact with the magnetic fields generated by the first 83 and second 121 sets of permanent magnets 32, 34, respectively, to generate a force that moves the first 32 and second 34 permanent magnets, the secondary carrier 126 and the first 82 and second 120 piston rods along the piston rod axis 38. Thus, movement of the secondary carrier 126 moves both pistons 80, 122 simultaneously in the same direction, i.e. the first 80 and second 122 pistons move in phase. In particular, the first 82 and second 120 piston rods move in the first direction 50 and subsequently in the second direction 52 opposite the first direction 50 to move the first 82 and second 120 piston rods and thus the first 80 and second 122 pistons, respectively, in a continuous reciprocating linear motion suitable for the first 60 and second 106 compressor and at a desired operating speed.

[0030] Referring to Fig. 8, a partial cross-sectional view of an alternate embodiment for a guidance assembly 134 is shown. In this embodiment, the guidance assembly 134 includes two moveable secondary carriers. In particular, the guidance assembly 134 includes a first secondary carrier 136 attached to the first end 130 of the first piston rod 82 and a second secondary carrier 138 attached to the second end 132 of the second piston rod 120.

[0031] Thus, the first set 45 of primary windings 42A, 42B, 42C, 44A, 44B, 44C may be controlled independently from the second set 47 of primary windings 42A, 42B, 42C, 44A, 44B, 44C to provide independent magnetic fields. Thus, the first compressor 60 may be operated at a different speed than the second compressor 106. In addition, providing independently controllable magnetic fields enables out of phase movement of the first 80 and second 122 pistons. For example, the first piston 80 may move in first direction 50 at the same time that second piston 122 moves in second direction 52.

[0032] Referring to Fig. 9, a partial cross sectional view of a compound linear reciprocating compressor drive 140 is shown. The drive 140 includes a frame 142 located between first 144 and second 146 compressor cylinders having first 148 and second 150 piston rods, respectively, that are connected to associated pistons. Alternatively, only one compressor cylinder may be used. The frame 142 includes a moveable core portion 152 that extends through spaced apart first 154 and second 156 permanent magnets to form a series configuration. In another embodiment, the first 154 and second 156 permanent magnets may be arranged in a parallel arrangement or a combination thereof. First 158 and second 160 ends of the core portion 152 are attached to first 162 and second 164 ends of the first 148 and second 150 piston rods, respectively. Alternatively, an intermediate guidance assembly may be attached between the frame 142 and the first 144 and second 146 compressor cylinders.

[0033] At least one primary winding is located adjacent the first 154 and second 156 permanent magnets. In an embodiment, first 166 and second 168 primary windings are located adjacent the first 154 and second 156 permanent magnets, respectively. In use, magnetic fields generated by the primary winding interact with the magnetic fields generated by the first 154 and second 156 permanent magnets to generate a force that moves the first 154 and second 156 permanent magnets, the core portion 152, piston rods 148, 150 and associated pistons along the piston rod axis 38 in a reciprocating linear motion (i.e. in the first 50 and second 52 directions) and at a desired operating speed as previously described.

[0034] It is understood that additional or fewer primary windings 166, 168 and/or permanent magnets 154, 156 may be used in order to increase or decrease the amount of force used to drive the associated pistons. In addition, only one of the primary windings 166, 168 may be energized so as to provide partial power as desired. In accordance with the invention, the frame 142 enables establishment of a standardized frame that may be used in connection with any conventional reciprocating compressor having a piston rod.

[0035] The guidance assemblies of the invention may be connected to a piston rod of any reciprocating compressor thus enabling the use of a compressor cylinder that is suitable for a particular application. Aspects of the invention also enable the use of varied cylinder designs thereby providing a modular configuration capability that facilitates the ability to accommodate varying process conditions, gases, and flows. In addition, aspects of the invention enable the cylinders to operate in a double acting, single acting or non-acting mode of operation as needed by the selected application. Further, the ability to control compressor capacity is substantially enhanced by being able to change the rate of linear motion. In another aspect, guidance assemblies of the invention may be retrofitted to compressors already in use in industry. [0036] The invention replaces running gear used in a conventional reciprocating compressor such as a crankshaft, connecting rod, crosshead guide and associated components. The invention also removes the need for an oil lubricated reciprocating compressor frame. In addition, couples in the compressor drivetrain are eliminated along with the need for torsional tuning devices. Further, the invention provides a reciprocating compressor having a substantially smaller footprint and lower cost than a conventional reciprocating compressor.

[0037] While particular embodiments of the present disclosure have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the disclosure. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this disclosure.

Claims

CLAIMS What is claimed is:

1. A linear motor for moving a first piston rod of a first reciprocating compressor, comprising:

a guidance assembly having a moveable first secondary carrier that is attached to the first piston rod;

at least one permanent magnet attached to the secondary carrier;

at least one primary winding attached to the guidance assembly; and a controller that controls power supplied to the primary winding to generate a magnetic field that interacts with a magnetic field generated by the permanent magnet to provide a force that moves the permanent magnet, the first secondary carrier and the first piston rod in a reciprocating linear motion.

2. The linear motor according to claim 1, wherein the first secondary carrier includes at least one wing element and at least one permanent magnet is attached to the wing element.

3. The linear motor according to claim 1, wherein the first secondary carrier is attached to a second piston rod of a second reciprocating compressor and movement of the secondary carrier causes simultaneous movement of the first and second piston rods.

4. The linear motor according to claim 1, wherein the guidance assembly includes a second secondary carrier attached to a second piston rod of a second reciprocating compressor wherein the second secondary carrier includes at least one permanent magnet located adjacent at least permanent winding to enable independent control of the first and second piston rods.

5. The linear motor according to claim 1, further including an extension piece located between the first compressor and the guidance assembly.

6. The linear motor according to claim 1, wherein a pair of permanent magnets arranged in series are attached to the second carrier.

7. A linear motor for moving a piston rod of a reciprocating compressor, comprising:

a guidance assembly having a moveable secondary carrier that is attached to the piston rod, wherein the secondary carrier includes first and second wing elements; first and second permanent magnets attached to the first and second wing elements, respectively;

first and second primary windings located adjacent the first and second magnets, respectively, wherein the first and second primary windings are attached to the guidance assembly; and

a controller that controls power supplied to the first and second primary windings to generate respective magnetic fields that interact with respective magnetic fields generated by the first and second permanent magnets to provide a force that moves the first and second permanent magnets, the secondary carrier and the piston rod in a reciprocating linear motion.

8. The linear motor according to claim 7, wherein the first and second wing elements are oriented substantially horizontally.

9. The linear motor according to claim 8, further including third and fourth wing elements each including at least one permanent magnet wherein the third and fourth wing elements are oriented substantially vertically.

10. The linear motor according to claim 7, wherein the first secondary carrier is attached to a second piston rod of a second reciprocating compressor and movement of the secondary carrier causes in phase movement of the first and second piston rods.

11. The linear motor according to claim 7 wherein the guidance assembly includes a second secondary carrier attached to a second piston rod of a second reciprocating compressor wherein the second secondary carrier includes at least one permanent magnet located adjacent at least permanent winding to enable independent control of the first and second piston rods.

12. The linear motor according to claim 7, further including an extension piece located between the first compressor and the guidance assembly.

13. The linear motor according to claim 7, wherein the permanent magnets are arranged in series.

14. A method of moving a piston rod of a reciprocating compressor, comprising:

providing first and second permanent magnets on a moveable first secondary carrier that is attached to the piston rod;

providing first and second primary windings which generate magnetic fields that interact with magnetic fields generated by the first and second permanent magnets; and

controlling the magnetic fields generated by the first and second primary windings to provide a force that moves the first and second permanent magnets, the secondary carrier and the piston rod in a reciprocating linear motion.

15. The method according to claim 14, wherein the first and second wing elements are oriented substantially horizontally.

16. The method according to claim 15, further providing third and fourth wing elements each including at least one permanent magnet wherein the third and fourth wing elements are oriented substantially vertically.

17. The method according to claim 14, further providing a second piston rod of a second reciprocating compressor attached to the first secondary carrier wherein movement of the first secondary carrier causes in phase movement of the first and second piston rods.

18. The method according to claim 14, further providing a second secondary carrier attached to a second piston rod of a second reciprocating compressor wherein the second secondary carrier includes at least one permanent magnet located adjacent at least permanent winding to enable independent control of the first and second piston rods.

19. The method according to claim 14, further including an extension piece located between the first compressor and the secondary carrier.

20. The method according to claim 14, wherein the permanent magnets are arranged in series.