WO2011062705A1

WO2011062705A1 - Viscoelastic compressor pulsation dampener

Info

Publication number: WO2011062705A1
Application number: PCT/US2010/052198
Authority: WO
Inventors: Omar M. Kabir; John C. Bartos
Original assignee: Cameron International Corp
Current assignee: Cameron International Corp
Priority date: 2009-11-17
Filing date: 2010-10-11
Publication date: 2011-05-26
Anticipated expiration: 2012-05-17
Also published as: GB2488087A; RU2554661C2; BR112012011690A2; US20110116940A1; RU2012124791A; GB201210610D0; CN102667152A

Abstract

A system, in certain embodiments, includes a pulsation dampener for minimizing the adverse effects of pulsation waves in a process fluid generated by a reciprocating compressor. The pulsation dampener may be installed proximate to the source of the pulsation waves and external to a main flow path of the process fluid being compressed within the reciprocating compressor. More specifically, in certain embodiments, the pulsation dampener may be a pulsation dampening valve enclosure configured to at least partially encase a valve assembly of the reciprocating compressor. The pulsation dampening valve enclosure may be filled with a pulsation dampening material, such as a wire mesh material, a viscoelastic material, an elastomeric material, or a combination thereof.

Description

VISCOELASTIC COMPRESSOR PULSATION

DAMPENER

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Non-Provisional Patent

Application No. 12/620,506, entitled "Viscoelastic Compressor Pulsation

Dampener", filed on November 17, 2009, which is herein incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates generally to reciprocating machinery, such as compressors. More particularly, the present invention relates to systems and methods for dampening pulsations generated by reciprocating machinery, such as compressors.

BACKGROUND

[0003] This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better

understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.

[0004] A reciprocating compressor is a positive-displacement device, which utilizes a motor to drive one or more pistons via a crank shaft and connecting rods. Each piston reciprocates back and forth in a compression cylinder to intake a process fluid (e.g., natural gas) into a chamber, compress the process fluid within the chamber, and exhaust the process fluid from the chamber to a desired output. However, due to their very nature, reciprocating compressors tend to generate a certain degree of pulsations. These pulsations can cause the pressure and temperature of the compressed process fluid to vary cyclically. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:

[0006] FIG. 1 is a perspective view of an exemplary reciprocating compressor in accordance with an embodiment of the present invention;

[0007] FIG. 2 is a cross-sectional view of the exemplary reciprocating compressor of FIG. 1 , illustrating internal components of the reciprocating compressor;

[0008] FIG. 3 is a partial perspective view of the exemplary reciprocating compressor of FIGS. 1 and 2;

[0009] FIG. 4A is a cross-sectional side view of a compression cylinder of the exemplary reciprocating compressor of FIG. 3 when a piston within the compression cylinder is in a first stroke position;

[0010] FIG. 4B is a cross-sectional side view of the compression cylinder of the exemplary reciprocating compressor of FIG. 3 when the piston within the compression cylinder is in a second stroke position;

[0011] FIG. 5 is a side view of a reciprocating compressor unit having two reciprocating compressor cylinders, each associated with an inlet pulsation bottle and an outlet pulsation bottle;

[0012] FIG. 6 is a chart of the outlet pressure pulsation of a process fluid from one of the outlet pulsation bottles of FIG. 5;

[0013] FIG. 7 is a partial perspective view of the reciprocating compressor of FIG. 3 utilizing pulsation dampeners external to a main flow path of the process fluid stream; and

[0014] FIG. 8 is a chart of the outlet pressure pulsation of the process fluid from the compression cylinder outlet of FIG. 7. DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0015] One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these

embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure.

[0016] When introducing elements of various embodiments of the present invention, the articles "a," "an," "the," "said," and the like, are intended to mean that there are one or more of the elements. The terms "comprising," "including," "having," and the like are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, the use of "top," "bottom," "above," "below," and variations of these terms is made for

convenience, but does not require any particular orientation of the components.

[0017] As described in detail below, the disclosed embodiments include systems and methods for reducing the adverse effects of pulsation waves generated in a reciprocating machine, such as a reciprocating compressor, reciprocating pump, adjacent intake and exhaust valves, and so forth. Indeed, the disclosed embodiments may be extended to any other applications which may benefit from pulsation dampening. In certain embodiments, a pulsation dampener may be installed proximate to the source of the pulsation waves and external to a main flow path of the process fluid being compressed within the reciprocating compressor. More specifically, in certain embodiments, the pulsation dampener may be a pulsation dampening valve enclosure configured to at least partially enclose a valve assembly of the reciprocating compressor. The pulsation dampening valve enclosure may be filled or lined with a pulsation dampening material, such as a wire mesh material, a viscoelastic material (e.g., a viscoelastic polymer), an elastomeric material, or a combination thereof.

Viscoelastic materials may be characterized as materials which exhibit

substantially time-dependent strain (e.g., non-linear strain) with respect to stress.

[0018] Using pulsation dampening materials within the pulsation dampening valve enclosures may lead to several tangible benefits. For example, acoustic energy within the process fluid may be dampened proximate to the source of the pulsations without extra pressure losses that may occur through piping and vessels of other pulsation dampening techniques. This may enhance the overall power consumption of the reciprocating compressor. In addition, the pulsation dampening valve enclosures not only absorb the pulsation level of the pressure waves in the process fluid stream, but also dampen the vibration caused by the acoustic waves. As such, the reciprocating compressor and associated

equipment and piping upstream and downstream of the reciprocating compressor may be protected from excessive vibration damage. Furthermore, the pulsation dampening valve enclosures may generally be much smaller than other pulsation dampening techniques because they dampen the pulsation directly at the compressor valves, where the pulsation is generated. Therefore, the overall installed cost of the reciprocating compressor may be drastically reduced using the pulsation dampening valve enclosures.

[0019] Turning now to the figures, an exemplary reciprocating compressor 10 is illustrated in FIG. 1 . In the presently illustrated embodiment, the reciprocating compressor 10 includes a pair of compression cylinders 12 coupled to a frame 14. A variety of internal components may be disposed within the compression cylinders 12 and the frame 14 to enable compression of fluids introduced into the reciprocating compressor 10 within the compression cylinders 12. For example, in certain embodiments, the reciprocating compressor 10 may be utilized to compress natural gas. However, in other embodiments, the reciprocating compressor 10 may be configured and/or utilized to compress other fluids. [0020] A mechanical power source or driver 16, such as a combustion engine or an electric motor, may be coupled to the reciprocating compressor 10 to provide mechanical power to the various internal components to enable compression of the fluid within the compression cylinders 12. To facilitate access to such internal components, as may be desired for diagnostic or maintenance purposes, openings in the frame 14 may be provided and selectively accessed via removable covers 18. Further, the compression cylinders 12 may also include valve assemblies 20 for controlling flow of the fluid through the

compression cylinders 12.

[0021] Although the exemplary reciprocating compressor 10 is illustrated as a two-stroke reciprocating compressor, other compressor configurations may also employ and benefit from the presently disclosed techniques. For instance, in other embodiments, the reciprocating compressor 10 may include a different number of cylinder strokes, such as a four-stroke compressor, a screw

compressor, or the like. Further, other variations are also envisaged, including variations in the length of stroke, the operating speed, and the size, among other things.

[0022] FIG. 2 is a cross-sectional view of the exemplary reciprocating compressor 10 of FIG. 1 , illustrating internal components of the reciprocating compressor 10. In the presently illustrated embodiment, the frame 14 of the exemplary reciprocating compressor 10 includes a hollow central body or housing 22 that generally defines an interior volume 24 within which various internal components may be housed, such as a crank shaft 26. In one embodiment, the central body 22 may have a generally curved or cylindrical shape. It should be noted, however, that the central body 22 may have other shapes or configurations in accordance with the disclosed embodiments.

[0023] In operation, the driver 16 rotates the crank shaft 26 supported within the interior volume 24 of the frame 14. In one embodiment, the crank shaft 26 is coupled to crossheads 30 via connecting rods 28 and pins 32. The crossheads 30 are disposed within crosshead guides 34, which generally extend from the central body 22 and facilitate connection of the compression cylinders 12 to the reciprocating compressor 10. In one embodiment, the reciprocating compressor 10 includes two crosshead guides 34 that extend generally perpendicularly from opposite sides of the central body or housing 22, although other configurations may be used. The rotational motion of the crank shaft 26 is translated via the connecting rods 28 to reciprocal linear motion of the crossheads 30 within the crosshead guides 34.

[0024] The compression cylinders 12 are configured to receive a fluid for compression. The crossheads 30 are coupled to pistons 36 disposed within the compression cylinders 12, and the reciprocating motion of the crossheads 30 enables compression of fluid within the compression cylinders 12 via the pistons 36. Particularly, as a piston 36 is driven forward (i.e., outwardly from central body 22) into a compression cylinder 12, the piston 36 forces the fluid within the cylinder into a smaller volume, thereby increasing the pressure of the fluid. A discharge valve of valve assembly 20 may then be opened to allow the pressurized or compressed fluid to exit the compression cylinder 12. The piston 36 may then stroke backward, and additional fluid may enter the compression cylinder 12 through an inlet valve of the valve assembly 20 for compression in the same manner described above.

[0025] FIG. 3 is a partial perspective view of the exemplary reciprocating compressor 10 of FIGS. 1 and 2. As illustrated, the reciprocating compressor 10 includes one of the compression cylinders 12 coupled to the frame 14. Various components and covers are removed from the reciprocating compressor 10 as illustrated in FIG. 3. However, the reciprocating compressor 10 includes a variety of similar components as discussed above with reference to FIGS. 1 and 2. For example, the frame 14 includes the central body 22 with the interior volume 24, which houses the crank shaft 26. In addition, the central body 22 is coupled to a pair of crosshead guides 34, which lead to respective compression cylinders 12. [0026] In certain embodiments, a process fluid (e.g., natural gas) may be received into the compression cylinder 12 through the compression cylinder inlet 38, as illustrated by arrow 40, and discharged through the compression cylinder outlet 42, as illustrated by arrow 44. As the piston 36 moves back and forth within the interior of the compression cylinder 12, as illustrated by arrow 46, the process fluid will enter into first and second chambers within the compression cylinder 12 where it is compressed in an alternating manner, as described in greater detail below. In addition, a plurality of first-stage and second-stage valve assemblies, which reside in first-stage and second-stage valve housings 48, 50, respectively, may help control the flow of the process fluid through the first and second chambers within the compression cylinder 12.

[0027] For example, FIGS. 4A and 4B illustrate how the process fluid flows through first and second chambers 52, 54 of the compression cylinder 12 of the reciprocating compressor 10 of FIG. 3. In particular, FIG. 4A is a cross-sectional side view of the compression cylinder 12 when a shaft 56 connected to one of the crossheads 30 of FIG. 2 has caused the piston 36 to translate into a first stroke position, as illustrated by arrow 58. In this position, the process fluid may be drawn into the first chamber 52 through the compression cylinder inlet 38, as illustrated by arrow 60. In particular, a first inlet valve assembly 62 may be in an open position to allow the process fluid to enter the first chamber 52. However, a first outlet valve assembly 64 may be in a closed position to block the process fluid from exiting the first chamber 52 through the compression cylinder outlet 42.

[0028] Conversely, when the piston 36 is in the first stroke position illustrated in FIG. 4A, the process fluid is not being drawn into the second chamber 54 of the compression cylinder 12. Rather, a second inlet valve assembly 66 may be in a closed position to block the process fluid from entering the second chamber 54 through the compression cylinder inlet 38. However, a second outlet valve assembly 68 may be in an open position to allow the process fluid to exit the second chamber 54 through the compression cylinder outlet 42, as illustrated by arrow 70. In particular, when the piston 36 is in the first stroke position, the process fluid in the second chamber 54 has been compressed while the process fluid in the first chamber 52 has not yet been compressed.

[0029] By way of comparison, FIG. 4B is a cross-sectional side view of the compression cylinder 12 when the shaft 56 has caused the piston 36 to translate into a second stroke position, as illustrated by arrow 72. In this position, the process fluid is drawn into the second chamber 54 through the compression cylinder inlet 38, as illustrated by arrow 74. In particular, the second inlet valve assembly 66 may be in an open position to allow the process fluid to enter the second chamber 54. However, the second outlet valve assembly 68 may be in a closed position to block the process fluid from exiting the second chamber 54 through the compression cylinder outlet 42.

[0030] Conversely, when the piston 36 is in the second stroke position illustrated in FIG. 4B, the process fluid is not being drawn into the first chamber 52 of the compression cylinder 12. Rather, the first inlet valve assembly 62 may be in a closed position to block the process fluid from entering the first chamber 52 through the compression cylinder inlet 38. However, the first outlet valve assembly 64 may be in an open position to allow the process fluid to exit the first chamber 52 through the compression cylinder outlet 42, as illustrated by arrow 76. In particular, when the piston 36 is in the second stroke position, the process fluid in the first chamber 52 has been compressed while the process fluid in the second chamber 54 has not yet been compressed.

[0031] Therefore, as the piston 36 translates between the first and second stroke positions illustrated in FIGS. 4A and 4B, the process fluid will be compressed in the first and second chambers 52, 54 within the compression cylinder 12 in an alternating manner. More specifically, the first and second inlet valve assemblies 62, 66 and the first and second outlet valve assemblies 64, 68 may help control the flow of the process fluid through the first and second chambers 52, 54 while the process fluid is being compressed in an alternating manner. [0032] In certain embodiments, the valve assemblies may be associated with cylindrical vessels, which may act to protect the valve assemblies as they alternate between open and closed positions. In particular, the first inlet valve assembly 62 may be associated with a first inlet valve enclosure 78, the first outlet valve assembly 64 may be associated with a first outlet valve enclosure 80, the second inlet valve assembly 66 may be associated with a second inlet valve enclosure 82, and the second outlet valve assembly 68 may be associated with a second outlet valve enclosure 84. These valve enclosures 78, 80, 82, 84 may at least partially enclose their respective valve assemblies 62, 64, 66, 68.

[0033] In addition, each of the valve assemblies 62, 64, 66, 68 may be associated with respective valve retainers, which hold their respective valve assembly in place. In particular, the first inlet valve assembly 62 may be associated with a first inlet valve retainer 86, the first outlet valve assembly 64 may be associated with a first outlet valve retainer 88, the second inlet valve assembly 66 may be associated with a second inlet valve retainer 90, and the second outlet valve assembly 68 may be associated with a second outlet valve retainer 92.

[0034] Although illustrated in FIGS. 4A and 4B as including only a first and second inlet valve assembly 62, 66 and a first and second outlet valve assembly 64, 68, in certain embodiments, numerous combinations of inlet and outlet valve assemblies may be used. For example, in reciprocating compressors 10 having higher total throughput of compressed process fluid, more than two inlet valve assemblies and more than two outlet valve assemblies may be used to

accommodate the higher process fluid flow rates. However, as described above with respect to FIGS. 4A and 4B, in certain embodiments, the reciprocating compressor 10 may be a two-stroke reciprocating compressor with two sets of inlet and outlet valve assemblies, regardless of the number of inlet or outlet valve assemblies in each set.

[0035] The reciprocating manner of compression within the reciprocating compressor 10 may, by its very nature, generate a certain degree of pulsation in not only the compressed process fluid downstream of the reciprocating compressor 10 but also upstream of the reciprocating compressor 10. This is due at least in part to the alternating manner in which the two volumes of process fluid (e.g. one volume of process fluid in the first chamber 52 and another volume of process fluid in the second chamber 54) in the compression cylinder 12 of the reciprocating compressor 10 are compressed. In other words, the acceleration and deceleration of the piston 36 between the first and second chambers 52, 54 of the compression cylinder 12 causes pulsating pressure waves in the process fluid stream. As a result, the pressure waves will generally propagate within the process fluid in both an upstream direction (e.g., back through the compression cylinder inlet 38) and a downstream direction (e.g., forward through the compression cylinder outlet 42) with respect to the reciprocating compressor 10.

[0036] This pressure wave propagation can make the pressure of the compressed process fluid less predictable as well as generating pressures that can approach and potentially exceed pressure ratings of piping and other equipment proximate to the reciprocating compressor 10 (e.g., the reciprocating compressor housing 22, crank shaft 26, valves, and so forth). In addition, in extreme situations, pulsation surge conditions may potentially cause excessive vibration levels within the reciprocating compressor 10, which may cause wear or damage to the reciprocating compressor 10 and associated piping and

equipment. As such, techniques to minimize the effects of the pulsations generated in the process fluid may enable more predictable and reliable operation of the reciprocating compressor 10.

[0037] One method for addressing the pulsation problem described above is to use large vessels, which may be referred to as pulsation bottles to absorb some of the kinetic and potential energy in the process fluid stream. FIG. 5 is a side view of a reciprocating compressor unit 94 having two reciprocating compressors 10, each associated with an inlet pulsation bottle 96 and an outlet pulsation bottle 98. More specifically, each of the inlet pulsation bottles 96 may be upstream of the compression cylinder inlet 38 of their respective reciprocating compressor 10 while each of the outlet pulsation bottles 98 may be downstream of the compression cylinder outlet 42 of their respective reciprocating compressor 10.

[0038] Both the inlet and outlet pulsation bottles 96, 98 generally include an internal separating diaphragm and choke tube. The separating diaphragms of the pulsation bottles 96, 98 provide a large volume, which allows the velocity of the process fluid stream to be reduced since the area in the pulsation bottles 96, 98 increases. In addition, the choke tubes of the pulsation bottles 96, 98 provide attenuation of the pressure wave in the process fluid stream. Both the separating diaphragm and the choke tube absorb the kinetic energy of the process fluid stream, resulting in reduction of the maximum pulsation pressure of the process fluid stream. In particular, the process fluid stream flows directly through the pulsation bottles 96, 98, which act as pulsation dampeners. In other words, the process fluid stream enters the pulsation bottles 96, 98 through respective inlets and exits the pulsation bottles 96, 98 through respective outlets. As such, the pulsation dampening occurs directly in the main flow path of the process fluid stream.

[0039] However, as illustrated in FIG. 5, the pulsation bottles 96, 98 and associated piping and equipment may generally be very large and, therefore, expensive to manufacture. In addition, the pulsation bottles 96, 98 cause considerable pressure losses since they effectively reduce the velocity of the process fluid stream. As such, the pulsation bottles 96, 98 adversely affect the overall efficiency of the reciprocating compressor unit 94. In particular, a certain degree of power consumption of the reciprocating compressor unit 94 is directly lost in the pulsation bottles 96, 98. Furthermore, the pulsation bottles 96, 98 still generally allow some of the high frequency pulsation waves to escape.

[0040] For example, FIG. 6 is a chart 100 of the outlet pressure pulsation of the process fluid from one of the outlet pulsation bottles 98 of FIG. 5. As illustrated, the mean outlet pressure 102 of the process fluid may be 1 ,500 pounds per square inch atmospheric (psia). As illustrated, the actual outlet pressure 104 pulsates between a maximum outlet pressure 106 of 1 ,550 psia and a minimum outlet pressure 108 of 1 ,450 psia. The mean outlet pressure 102 of 1 ,500 psia is, of course, exemplary and not intended to be limiting. Rather, the amount of pulsation illustrated in FIG. 6 is generally intended to establish a baseline for the amount of pulsation present when using the pulsation bottles 96, 98 described above with respect to FIG. 5, which may later be compared to the amount of pulsation present using other pulsation dampening embodiments described herein.

[0041] As described above, one of the drawbacks of using the pulsation bottles 96, 98 of FIG. 5 is the amount of pressure loss that is incurred in reducing the velocity of the process fluid stream. This is due at least in part to the fact that the pulsation dampening occurs directly in the main flow path of the process fluid stream. In other words, since the pulsation dampening occurs in the inlet and outlet pulsation bottles 96, 98 of FIG. 5, which are directly in the main flow path of the process fluid stream, the dampening of the pulsation levels occurs directly on the process fluid stream (e.g., via losses in kinetic and potential energy of the process fluid stream). One method for improving the pulsation dampening of the pulsation bottles 96, 98 of FIG. 5 may be to move the pulsation dampening out of the main flow path of the process fluid stream.

[0042] FIG. 7 is a partial perspective view of the reciprocating compressor 10 of FIG. 3 utilizing pulsation dampeners external to the main flow path of the process fluid stream. In particular, the compression cylinder 12 illustrated in FIG. 7 may have one or more first inlet valve enclosures 78, one or more first outlet valve enclosures 80, one or more second inlet valve enclosures 82, and one or more second outlet valve enclosures 84. As described above with respect to FIGS. 4A and 4B, the first inlet valve enclosures 78 may at least partially encase first inlet valve assemblies 62, the first outlet valve enclosures 80 may at least partially encase first outlet valve assemblies 64, the second inlet valve

enclosures 82 may at least partially encase second inlet valve assemblies 66, and the second outlet valve enclosures 84 may at least partially encase second outlet valve assemblies 68. [0043] In addition, each of the valve enclosures 78, 80, 82, 84 may be attached to valve retainers, which hold their respective valve assembly in place. Again, as described above with respect to FIGS. 4A and 4B, the first inlet valve enclosures 78 may be attached to first inlet valve retainers 86, the first outlet valve enclosures 80 may be attached to first outlet valve retainers 88, the second inlet valve enclosures 82 may be attached to second inlet valve retainers 90, and the second outlet valve enclosures 84 may be attached to second outlet valve retainers 92.

[0044] Rather than using the pulsation bottles 96, 98 for pulsation dampening as described above with respect to FIGS. 5 and 6, the pulsation dampeners in the embodiment illustrated in FIG. 7 may be located within each of the valve enclosures 78, 80, 82, 84. In this manner, the pulsation dampening may be located closer to the source of the pulsation (e.g., the first and second chambers 52, 54 of the compression cylinder 12, described above with respect to FIGS. 4A and 4B). As such, the pulsations may be minimized before they propagate into the piping system in upstream and downstream directions.

[0045] In addition, locating the pulsation dampening in the valve enclosures 78, 80, 82, 84 moves the pulsation dampening external to the main flow path of the process fluid stream. In other words, dampening of the high frequency pulsation waves in the process fluid stream occurs tangential to the interior volumes of the reciprocating compressor 10 through which the process fluid flows. More specifically, the process fluid stream does not flow through the valve enclosures 78, 80, 82, 84, which act as pulsation dampeners. Indeed, in certain embodiments, seals may be used to completely isolate the process fluid stream from interior volumes of the valve enclosures 78, 80, 82, 84, which may contain pulsation dampening materials, as described below. As such, the pulsation dampening occurs external to the main flow path of the process fluid stream. In other words, the pulsation dampening does not occur directly in the main flow path of the process fluid stream. [0046] In certain embodiments, the pulsation dampening of the valve enclosures 78, 80, 82, 84 may be accomplished by filling or lining an interior volume of the valve enclosures 78, 80, 82, 84 with a suitable dampening material for absorbing the pressure wave and acoustic wave energy directly from the process fluid stream without introducing appreciable pressure loss and/or kinetic and potential energy loss into the process flow stream. In certain embodiments, the interior volumes of the valve enclosures 78, 80, 82, 84 may be completely filled (e.g., 100%) or partially filled (e.g., 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, and so forth) with the pulsation dampening materials. In other embodiments, the interior volumes of the valve enclosures 78, 80, 82, 84 may have pulsation dampening materials lining interior walls of the interior volumes.

[0047] The dampening material used within the valve enclosures 78, 80, 82, 84 may, in certain embodiments, be a wire mesh of various densities, a viscoelastic material (e.g., a viscoelastic polymer or foam) of various dampening capabilities, one of various types of elastomeric materials, or a combination thereof. In general, the dampening material used may be any material that has pressure and acoustic dampening characteristics. More specifically, the types of energy that these materials absorb are sound energy, vibration energy, and pressure pulsation, and the materials may convert these types of energy into heat or friction energy. As such, any materials capable of internally absorbing friction or Coulomb energy and converting this absorbed energy into heat may be suitable for the pulsation dampening materials.

[0048] Using pulsation dampening materials within the valve enclosures 78, 80, 82, 84 that encase the valve assemblies 62, 64, 66, 68 of the compression cylinder 12 may lead to several tangible benefits. For example, acoustic energy within the process fluid may be dampened proximate to the source of the pulsations without the extra pressure losses that may occur through piping and vessels of other pulsation dampening techniques (e.g., the pulsation bottles 96, 98 of FIGS. 5 and 6). [0049] For example, FIG. 8 is a chart 1 10 of the outlet pressure pulsation of the process fluid from the compression cylinder outlet 42 of FIG. 7. As illustrated, the mean outlet pressure 102 of the process fluid may again be 1 ,500 psia.

However, as illustrated, the actual outlet pressure 104 only pulsates between a maximum outlet pressure 106 of 1 ,510 psia and a minimum outlet pressure 108 of 1 ,490 psia, as compared to pulsating between a maximum outlet pressure 106 of 1 ,550 psia and a minimum outlet pressure 108 of 1 ,450 psia, as before (e.g., FIG. 5). In other words, using pulsation dampening materials within the valve enclosures 78, 80, 82, 84 that encase the valve assemblies 62, 64, 66, 68 of the compression cylinder 12 of FIG. 7 may lead to substantially smaller variations between maximum and minimum outlet pressure 106, 108 than compared to using the pulsation bottles 96, 98 of FIG. 5.

[0050] In addition, using pulsation dampening materials within the valve enclosures 78, 80, 82, 84 that encase the valve assemblies 62, 64, 66, 68 of the compression cylinder 12 not only absorbs the pulsation level of the pressure waves in the process fluid stream, but also dampens the vibration caused by the acoustic waves. As such, the reciprocating compressor 10 and associated equipment and piping upstream and downstream of the reciprocating compressor 10 may be protected from excessive vibration damage. In addition, the extra power losses incurred by the pulsation bottles 96, 98 of FIG. 5 may be drastically reduced since the pulsation dampening occurs external to the main flow path of the process fluid stream. This will reduce the overall power consumption by the reciprocating compressor 10. Furthermore, the valve enclosures 78, 80, 82, 84 are generally much smaller than the pulsation bottles 96, 98 of FIG. 5. For example, in certain embodiments, the valve enclosures 78, 80, 82, 84 may be approximately 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, or more smaller than the pulsation bottles 96, 98 of FIG. 5. Therefore, the overall installed cost of the reciprocating compressor 10 may be drastically reduced using pulsation dampening materials within the valve enclosures 78, 80, 82, 84 that encase the valve assemblies 62, 64, 66, 68. [0051] While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.

Claims

CLAIMS:

1 . A system, comprising:

a compressor having a first chamber, an inlet, an outlet, a first inlet valve assembly configured to control a flow of a process fluid into the first chamber of the compressor through the inlet, and a first outlet valve assembly configured to control the flow of the process fluid out of the first chamber of the compressor through the outlet, wherein the flow of the process fluid defines a flow path; and at least one pulsation dampener external to the flow path, wherein the pulsation dampener is configured to dampen pulsation waves within the process fluid.

2. The system of claim 1 , wherein the at least one pulsation dampener comprises a pulsation dampening valve enclosure, wherein the pulsation dampening valve enclosure encases at least part of the first inlet valve assembly or the first outlet valve assembly.

3. The system of claim 2, wherein an interior volume of each pulsation dampening valve enclosure is filled with a pulsation dampening material.

4. The system of claim 3, wherein the pulsation dampening material comprises a wire mesh material.

5. The system of claim 3, wherein the pulsation dampening material comprises a viscoelastic material.

6. The system of claim 3, wherein the pulsation dampening material comprises an elastomeric material.

7. The system of claim 2, wherein the compressor comprises a reciprocating compressor.

8. The system of claim 7, wherein the reciprocating compressor comprises a two-stroke reciprocating compressor.

9. The system of claim 8, wherein the two-stroke reciprocating compressor comprises a second chamber, a second inlet valve assembly configured to control the flow of the process fluid into the second chamber of the two-stroke reciprocating compressor through the inlet, and a second outlet valve assembly configured to control the flow of the process fluid out of the second chamber of the two-stroke reciprocating compressor through the outlet.

10. The system of claim 9, wherein the first inlet valve assembly, the first outlet valve assembly, the second inlet valve assembly, and the second outlet valve assembly are each at least partially encased within a respective pulsation dampening valve enclosure.

1 1. A system, comprising:

a pulsation dampener configured to couple to a reciprocating compressor external to a flow path of a process fluid to be compressed within the

reciprocating compressor.

12. The system of claim 1 1 , wherein the pulsation dampener comprises a pulsation dampening valve enclosure configured to at least partially encase a valve assembly of the reciprocating compressor.

13. The system of claim 12, wherein an interior volume of the pulsation dampening valve enclosure is at least partially filled with a pulsation dampening material.

14. The system of claim 13, wherein the pulsation dampening material comprises a wire mesh material.

15. The system of claim 13, wherein the pulsation dampening material comprises a viscoelastic material.

16. The system of claim 13, wherein the pulsation dampening material comprises an elastomeric material.

17. The system of claim 1 1 , comprising the reciprocating compressor, wherein the pulsation dampener is coupled to the reciprocating compressor.

18. A method, comprising:

dampening pulsation waves in a process fluid generated by a

reciprocating machine using a pulsation dampener installed in the reciprocating machine external to a flow path of the process fluid flowing through the reciprocating machine.

19. The method of claim 18, wherein dampening the pulsation waves in the process fluid comprises dampening the pulsation waves using a pulsation dampening valve enclosure which at least partially encases a valve assembly of the reciprocating machine.

20. The method of claim 19, wherein dampening the pulsation waves in the process fluid comprises dampening the pulsation waves using a pulsation dampening material within an interior volume of the pulsation dampening valve enclosure.