U.S. patent application number 12/620506 was filed with the patent office on 2011-05-19 for viscoelastic compressor pulsation dampener.
This patent application is currently assigned to CAMERON INTERNATIONAL CORPORATION. Invention is credited to John C. Bartos, Omar M. Kabir.
Application Number | 20110116940 12/620506 |
Document ID | / |
Family ID | 44011406 |
Filed Date | 2011-05-19 |
United States Patent
Application |
20110116940 |
Kind Code |
A1 |
Kabir; Omar M. ; et
al. |
May 19, 2011 |
VISCOELASTIC COMPRESSOR PULSATION DAMPENER
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.
Inventors: |
Kabir; Omar M.; (Waller,
TX) ; Bartos; John C.; (Tomball, TX) |
Assignee: |
CAMERON INTERNATIONAL
CORPORATION
Houston
TX
|
Family ID: |
44011406 |
Appl. No.: |
12/620506 |
Filed: |
November 17, 2009 |
Current U.S.
Class: |
417/313 ;
417/540 |
Current CPC
Class: |
F04B 39/0044 20130101;
F04B 39/0027 20130101; F04B 39/0038 20130101 |
Class at
Publication: |
417/313 ;
417/540 |
International
Class: |
F04B 39/00 20060101
F04B039/00 |
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.
11. 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 11, 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 11, 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.
Description
FIELD OF THE INVENTION
[0001] 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
[0002] 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.
[0003] 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
[0004] 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:
[0005] FIG. 1 is a perspective view of an exemplary reciprocating
compressor in accordance with an embodiment of the present
invention;
[0006] FIG. 2 is a cross-sectional view of the exemplary
reciprocating compressor of FIG. 1, illustrating internal
components of the reciprocating compressor;
[0007] FIG. 3 is a partial perspective view of the exemplary
reciprocating compressor of FIGS. 1 and 2;
[0008] 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;
[0009] 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;
[0010] 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;
[0011] FIG. 6 is a chart of the outlet pressure pulsation of a
process fluid from one of the outlet pulsation bottles of FIG.
5;
[0012] 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
[0013] 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
[0014] 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.
[0015] 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.
[0016] 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.
[0017] 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.
[0018] 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.
[0019] 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.
[0020] 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.
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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.
[0032] 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.
[0033] 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.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] 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.
[0039] 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.
[0040] 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.
[0041] 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.
[0042] 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.
[0043] 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.
[0044] 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.
[0045] 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.
[0046] 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.
[0047] 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).
[0048] For example, FIG. 8 is a chart 110 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.
[0049] 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.
[0050] 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.
* * * * *